texts: Eagles carrying off a goat to its nest: How heavy is the young goat? How strong is the eagle? Here is my guess:

texts:
I posted a related question, here, trying to identify the exact subspecies of animals. In the documentary El Hombre y la Tierra, a golden eagle carries off some sort of juvenile(?) goat.

The Japanese golden eagle male weighs as little as 5.5 lbs, while the largest subspecies female weighs around 14 lbs. However, the largest species lives in Central Asia, and this footage is from Iberia, I believe. Therefore, it is more likely the subspecies is the one that lives in North Western Europe (I presume they reach south to the Iberian Peninsula), which weighs 7.7 lbs and 11 lbs on average for males and females respectively.

The question is how heavy a juvenile goat is likely to weight. The goat in the video does not look much smaller than the adults, though it is a little hard to tell. The Iberian ibex, which the goat supposedly is a member of, ranges in weight from 65 to 265 lbs.

If we estimated the goat to be a fraction of that lower estimate, say a quarter, that would be 16.25 lbs. If we took the 11 lb estimate for the golden eagle, that would mean it carried 147% of its body weight back to its nest. Wow!

The goat attacking the eagle in picture 2 must be an adult, either a male or a female. It does not seem much larger than the goat that was carried off in the first picture, however. This might mean the eagle carried off a goat significantly heavier than itself!

I would appreciate your input on my investigation into this matter. I feel this would be worth academic study.

Thank you.

PS: It was a lot of work to research and post this, so please don't delete it. I will repost it somewhere else if this is outside the scope of this stack exchange. Thank you for your understanding.


texts: Is it possible to make bacteria vulnerable to antibiotics it's resistant to?

texts:
Since bacteria becomes resistant to antibiotics after an unfinished course, is it possible to do anything to be able to get treatment with the same antibiotic again, and reverse the resistance in the bacteria?

Or, the bacteria with the resistance will stay resistant forever (until death)?

Edit:

There are some websites that are claiming that some natural remedies might be effective, like taking "Honey", which doesn't seem to be medical facts.


texts: How is the mRNA transported out of the endoplasmic reticulum?

texts: In eukaryotes the nuclear envelope is continuous with the ER, so what helps it out of that?


texts: Are there any known mutual symbiotic relationships that has more than two agents?

texts:
We are all familiar with the examples of symbiotic relationships in nature consisting of two agents, like lichen or the co-evolvement between certain birds and flowering plants.

Do we know of any mutually symbiotic relationships that has three of a even higher number of agents?

Edit: To make a implicit distinction clear, let's specify that the agents in question have distinctive and fully interdependent roles in the symbiosis. In contrast to a scenario where a range of bird species might co-evolve for a single specific flower and have the same role as pollinators in the symbiosis.

This image represents my current models in thinking about this:

The type I'm searching for here is mainly the "3-agent symbiosis", but the bidirectional one is of interest as well.


texts: Does the Spinoreticular Tract end in Brainstem?

texts:
According to this book on Springer spinoreticular tract is :

  As the name implies, the tract originates in the spinal cord and terminates in the reticular formation (RF) in the brainstem. While most of the fibers appear to terminate in the RF of the medulla and lower pons, some may ascend as far as the midbrain.

But according to Wikipedia :

  The spinoreticular tract is an ascending pathway in the white matter of the spinal cord, positioned closely to the lateral spinothalamic tract. The tract is from spinal cord—to reticular formation— to thalamus.

What I am unable to understand is if Wikipedia is true then why do we consider this tract as ending in the brainstem rather than ending in the thalamus?

Also I am getting different information about the location of the origin of spinoreticular fibres,

My Textbook says:

  The spinoreticular fibres begin from the spinal neurons mainly in lamina VII (also V and VIII).

But this site says:

  The term spinoreticular tract refers to a fiber bundle that arises largely from lamina I, lamina IV and lamina V of the spinal cord.

Which source is correct?


texts: Are sizes of potatoes normally distributed?

texts:
I'm currently researching the variability of sizes of potatoes when all of the potatoes in question have been harvested from a single field. One question keeps coming up in my statistical analyses: Under normal circumstances, are the sizes of potatoes - within a single field - normally distributed? (Please feel free to define the weasel words "normal circumstances" in the most helpful way you can imagine.)
Human height is often given as one of those classic examples of a normally distributed phenomenon. The little that I know about plant biology suggests that the central limit theorem applies just as much to potatoes as to the human body: the lengths of potato tubers and the lengths of human bones should have similarly-shaped distributions. But is that correct?

A bit of context to my original question: what I'm trying to do is to take the mean and standard deviation of my data and then, using the 68-95-99 rule, construct a series of confidence intervals, which I can then test or refine by looking at other data sets. Obviously, no real data set is going to conform perfectly to a model; I just need to know that, in principle, potato sizes are normally distributed enough that my method for drawing up confidence intervals isn't hopelessly misguided.


texts:
I read an argument that 1-3% of lymph is in peripheral blood.
However, I am not sure if this lymph is about lymphocytes in peripheral blood; not lymph itself.
Lymph gets exchanged between capillaries through Starling law powered by the heart and Frank-Starling mechanism.
In this way, it makes sense that some lymph is leaking out from capillaries into the bolod.

Can lymph be in the peripheral blood?


texts: How many nutrients do trees process daily?

texts:
Is this tree fact below that I have found on social media sites true? I don't know the source of the quote. It's pretty amazing. I'll be glad if someone can provide the source too!

Natural Wonders
Every day, a 40 foot tree takes in 50 gallons of dissolved nutrients from the soil, raises this mixture to its topmost leaves, converts it into 10 pounds of carbohydrates and releases about 60 cubic feet of pure oxygen into the air.


texts:
Dominant theory is that 'normal' dinosaurs went extinct from ether super volcano or meteor impact or combination of both. However there were aquatic dinosaurs that are not present at this day. Was it one of the events above that caused them to go extinct, or was it something else?

How did aquatic dinosaurs go extinct?


texts: Are there any viruses or bacteria which have evolved to withstand higher temperatures due to fever

texts:
My question was raised after receiving this information:

  The primary reason the body raises its temperature (via the Hypothalamus in this case) is that bacteria and viruses tend to optimally thrive at 98.6F, which is also your body's optimal operating temperature.

I am just wondering if there are any viruses or bacteria that have gained the ability to prosper under fever temperatures through evolution? If not, why not?  Is there any biological restriction stopping such viral evolution?

Update:

I will try to explain my question.  As far as I know, evolution helps species to adapt to their environment.  For example, when people started using antibiotics we got new bacteria resistant to those antibiotics.

If fever is part of the innate immune reaction to viruses and bacteria, why hasn't this resulted in selection for fever-resistant variants? Why has evolution apparently stopped in this case?


texts: Is there any difference between strain and mutation/mutant?

texts:
Experts are closely monitoring the strain, which has rapidly spread
through the country's south.

Source
Most of the media/newspapers are calling VOC-202012/01 a COVID strain, instead of a COVID mutation/mutant.
Is there any difference between strain and mutation?


texts:
Let's say that I have a population of Mus musculus in the lab. I divide it in a control group and a test group. The test group is constantly subjected to a stress (example: elevated UV radiation). Both groups are allowed to reproduce for 20 generations.
I want to fully characterize and compare what changed in each offspring (control vs test group) by using omics. The objective is then to integrate all these information in a new database with the pathways that change and by what magnitude.

Should I use genomics or/and exomics or/and epigenomics?
If I do one of the above and proteomics, why could I need the transcriptomics for?
Would the metabolomics, which are mainly punctual measures, add any valuable information?

This is a purely didatic exercise.


texts: Genetic variation in humans and model organisms (measured by SNPs)

texts:
I was wondering what is the range of SNP density across species and model organisms.

I.e., what would be a reasonable estimate for the SNP density (i.e., x SNPs for each 1 Kb) in:

humans
humans with the highest variation (i.e., Africans)
flies
mouse
lab mice with highest variation (i.e., isogenic lab mouse 1 with isogenic lab mouse 2 with the highest variation)
model organism with the highest snp density (could be lab or naturally occurring)


texts: Do the BLAST scores have any relation between them?

texts:
Is there any relation among the BLAST scores (E-value, similarity, identity, gap, bit score)?  Is the e-value score for an alignment proportional to other scores, such as similarity score (i.e. the lower the e-value, the higher the similarity)?

Thank you!


texts: Is there any (practical) way to control a rodent population without predators?

texts: It seems that New York has tried a number of ways to reduce their rat population, recently with fall traps. Unless they can kill all of the rats at once, it seems that this will just free up resources for the surviving rats to use. A feral cat population (which would increase in response to its food resource, i.e., the rats) seems to be the best way to control this. From an ecological perspective, are there alternatives to controlling a population of rodents, apart from using predators?


texts: Independent contrasts with non-homologous traits

texts: I have morphometric measurements for a trait across various animal taxa, and would like to study the relationship between the size of this trait, and the animals' body size. In theory, I can account for the non-independence of the data with phylogenetic methods, such as independent contrasts. However, I have very different groups in my tree (for example insects and lizards), and even within more closely related groups, the structures are often not homologous. Does this present a problem for independent contrasts/phylogenetic least squares? For example, the structure is not homologous between ants and flies, yet every (sensible?) tree would treat a fly as more similar to an ant than to any lizard. Is this justified if structures are analogous? If not, are there any ways to deal with this problem?


texts: Is sex linked inheritance independent of dominance?

texts:
I have a little challenge with what my lecturer said in class. I disagree with explanation but don't know how to convince myself. Please review and tell me your opinion.

Eye-color in drosophila is a sex-linked trait in which a white eye male was crossed with a red eye female. The F1 generation consist of 54 white eye and 49 red eye female; and 47 white eye and 50 red eye male. Explain.?

He said and I quote

  "the white eye male will transfer the white eye allele to the F1 female generation while the red eye female will transfer her red eye allele to the F1 male generation"

I disagreed because his explanation didn't account for the red eye f1 female generation and the white eye f1 male generation.... I proposed that the female parent was heterozygous for the eye color trait..... Hence a cross shows that the phenotypic ratios for either eye colors for any sex is 1/4...In response he acclaimed there's no dominance since it's a deviation from medellian principle.


texts: Transcription factor binding site located in intron

texts:
I have noticed that some TF binding sites are located in the introns of the genes.

I am puzzled about whether the TF only binds to DNA in the initiation stage of transcription and will detach during transcription. (I am thinking if the TF bind to the sense strand, it will block the PoLII for transcription, thus they should be removed.)

Many thanks in advance.


texts:
In a book about post-war Japan (Embracing Defeat, Dower) the author mentions a process for making sawdust at least partially edible, so it could be used in recipes in a 1:4 ratio with flour for cooking. The author says the sawdust was "fermented," as I recall.

My question is whether this is anything more than marginally possible. After all, kimchee, yogurt, beer, and other fermented foods aren't necessarily easier to digest. Is there a fermentation process involving bacteria that break down cellulose that might make wood even slightly nutritious?

My impression is that in forests the process of breaking down wood does not initially involve bacteria but other microorganisms; on the other hand, ruminants such as cows use bacteria to help them metabolize.

Thanks for any insight.


texts: The meaning of and standards for "specimen numbers"

texts:
I just read here:

  For example, in the research collection of the Natural History Museum in London, there is a bird specimen numbered 1886.6.24.20. This is a specimen of a kind of bird commonly known as the spotted harrier, which currently bears the scientific name Circus assimilis.

I am wondering what exactly that number 1886.6.24.20 means and how to find out more information. It seems it is structured to give some significance, such as perhaps year.month.day.incremented number. Wondering if this is unique to the Natural History Museum in London, or if this is how everywhere does it. By everywhere, I mean every museum. That is, wondering if there is a standard of some sort on how to number specimens.


texts:
Background

  If linkage strength between any two gene loci is 70%,
  what would be the amount of crossing over between
  these loci?

  (a) 15% (b)30% (c) 70% (d) none of
  these.

My approach at understanding the concept

I didn't find much about linkage strength from any authentic source.

I can think of two things :

The strength of a linkage would be greater if the spatial separation between two genes is less and the lesser if the separation is more. This is semantic. But,
how can it be represented in percentage? What does this 100 mean in this 70%? The separation between two genes can be more than 100 map units.

Question:

What does linkage strength mean? How is it related to amount of crossing over (number of recombinants)?

N.B. I would appreciate answers citing some authentic sources.


texts: What's the difference between CREs and DHSs?

texts: I would like to know what's the difference between cis-regulating elements and DNase I–hypersensitive sites, in order to produce a meaningful segregation of non coding elements affecting gene expression.


texts: In what ways can mechanisms of apoptosis be damaged?

texts: How many ways can an Apoptosis mechanism be made disfunctional or irreparably damaged? If a cell has damaged Apoptosis mechanisms and it divides will its daughter cells have such damage?


texts:
The wright-Fisher model of genetic drift is:

$$p_{ij} = \binom{2N}{j}\left(\frac{i}{2N}\right)^j \left(1- \frac{i}{2N}\right)^{2N-j} $$

,where $\binom{2N}{j}$ is a binomial coefficient.

From this equation one can infer that the expected heterozygostiy should decrease by $1-\frac{1}{2N}$ at each time step because:

$$E[x_{t+1}(1-x_{t+1}) \space|\space x_t] = (1-\frac{1}{2N})x_t(1-x_t)$$

I don't understand this equality. That might be very simple though! Can you help me making sense of it?

source


texts:
I was wondering whether plants could feel pain, for example, does grass feel pain when you mow the lawn? Or do the plants and trees that grow vegetables and fruits feel pain when you harvest them?

The internet is very vague about it. There are several articles on the internet, but they just say that plants do not feel pain, they only send out a chemical substance. Others say that almost all multicellular organisms feel pain, because pain is defined as any signal of having impaired tissue.

I think that plants can't feel pain because they have no nerves or central nervous system. However I'm not sure whether this means that plants can't feel pain.

Since the question is clear when pain is defined as any signal of having impaired tissue, I think it would be more interesting in the case that pain is defined as actual discomfort, like humans and animals (maybe it should be restricted to Eumetazoa) feel it.


texts: Optimal bacterial vegetative cell inactivation method(s) after subtilis spores germinated under pressure

texts:
I am writing a PhD research proposal and being a newbie in the field I am lost a little bit in the bacterial vegetative cell inactivation methods in foods.

I should propose two main methods to my future reseach team. The strategy is to germinate B. subtilis spores applying the high pressure, and then select one mild method to inactivate them.

My problem is to select max two most appropriate methods between:

Microwaves (MW)
Ozone (O3)
Pulsed electric fields (PEF)
Cold plasma (CP)
Ohmic heating (OH)
Ultrasound (US)
Ultraviolet (UV)
High/Low-energy Electron Beam (H/LEEB)
Chlorine dioxide (ClO2)
CO2 (HPCD, scCO2)

I need to select two methods..., I need to select only mild ones, to preserve the food taste - so I think the temperature should be <60° or max 70°... but what other criteria to take into consideration, being a newbie in this field?

Let's consider one of the method for dry foods, and another for liquids (juices, milk etc).


texts: What light intensity determines the start/end of a photoperiod in humans?

texts:
I'm reading this article, which discusses the influence of Long Photoperiod (LP) and Short Photoperiod (SP) on melatonin production:
HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster[1].

I'm interested in knowing what light intensity is interpreted as the onset and end of a light-dark photoperiod.

The referenced article indicates that animals were kept in cages, with a pre-set photoperiod duration, this sounds to me like it was done indoors. If it has been done indoors, then artificial lighting was involved, and I would guess it was an on-off affair, rather than gradual change or jumps in intensity.

The reason why I'm asking is that I'm trying to understand the implications of this article for humans, who may wake up before dawn, and spend some time under artificial lighting of various intensity before sunrise, and continue to function after sunset. For example a person may be looking at a TV or a monitor, and I would like to get an idea if this "presence of light" is enough to trigger photoperiod-related changes in the brain. Is there some "critical" density (or density at a specific wavelength) of light that signals the start/end of a photoperiod?

Ribelayga C, Pévet O, Simonneaux V. 2000. HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster. Regulatory, Integrative, and Comparative Physiology, 278(5), R1339-R1345.


texts: What is the reason behind choosing the reporter gene when experimenting on your gene of interest?

texts:
I noticed within example experiments in class that different reporter genes are chosen to be inserted near your gene of interest to prove whether or not the gene is being expressed. For example, you may insert the gene for fluorescence next to your gene of interest so you know if it is transcribed or not by whether the organism's cells are fluorescent and to what degree they are fluorescing at.

I have noticed in some experiments that have multiple versions that in one case they use the fluorescent gene and in the next a different gene (for example lactose). Both portions of the experiment use almost the exact same steps so why would they not choose the same reporter gene?


texts: What does entering of sex chromosomes to gametes mean during meiosis I?

texts:
I am reading one answer about meiosis:

  During meiosis I, the sex chromosomes separate and enter different
  sperm or egg cells (gametes).

I assume that sex chromosomes refer here to homologous chromosomes that experience crossing-over after meiosis that is exchange of genetical information.

Meiosis I refers here to female meiosis I and to male meiosis I.
In both cases, homologous chromosomes separate resulting in haploid cells after meiosis I.
These homologous chromosomes enter sperm or egg cells according to the writer, which I cannot understand, since the given chromosomes, now sister chromatids after meiosis I, do not enter physically anything, they just divide into haploid cells, gametes, after meiosis II.

What is the meaning of the word "enter" in the given sentence?

I am confused by the word "enter".
I am assuming that the word refers to enter something physically which is not the case in my opinion here.


texts: Will salting the ground kill insects and spiders?

texts:
I want to kill the insects and spiders living in my egress using something non-toxic to humans, dogs. I was thinking copious amounts of salt would kill earth dwelling bugs and what appears to be ground spiders with funnel like webs. The insects seem to be majorly silverfish. I am in Missoula Montana.

I think the bugs are coming from the egress. Here's an internet photo similar to my egress. The ground at the bottom is the area in question.


texts: Are there any fruits that rely on dispersal of their seeds using excrement?

texts:
Are there any fruits that have seeds which can survive the digestive entirety of an animal's digestive system and remain germinable once passed on in animal excrement?

Perhaps this is the primary function of all seeded fruits and I'm just fundamentally unaware of the intended biological processes. If so, then why do poisonous seeded fruits exist?


texts: What is a simple protocol for staining cells in suspension?

texts:
I am an engineering student studying how electric fields affect cells, specifically the phenomena of electroporation in living cells.

I know that electroporation is widely used for introducing genes into cells, but running a full transfection experiment is not so feasible in the lab I am working in.

My question is:

If I want to demonstrate the principle of electroporation, i.e. that cells open up and intake substances from the environment, by using some kind of a dye which i can later visualize, what could be a good model for this type of experiment? Specifically - what dye, what cells could be used for this?


texts: Do males of all sexual species have Y chromosomes?

texts: I know for instance some cells are sexual, so, this got me wondering, do the males of all species that have distinct sexes have Y chromosomes?


texts: Does the energy from ATP hydrolysis vary among different cells?

texts: I know that when ATP is hydrolyzed into ADP it gives 7.3 kcal/mol. The question is, does this value vary among different types of cells?


texts: What's going on when roots turn green and grow into the air?

texts:
You're looking at a hibiscus and an orchid growing in the same pot. I'm curious why the hibiscus started growing green roots into the air. Or am I looking at a third plant that somehow made its way into the pot?

July 27th

All it does is branch and get longer.

There are no leaves and the shoot doesn't thicken or turn to bark.

A new sprout appears every few days.

Is the hibiscus so root bound it's trying to escape the pot?

July 9th


texts: Why do we feel tired if we sleep excessively?

texts: When we eat, finally we feel full. I know which mechanism causes the sensation of being full. But when we sleep excessively we often still want more sleep. Why does this happen? Is there a mechanism underlying this?


texts: What are these strings used to describe animals?

texts:
For example, what's a $dt^{sz}$ hamster? (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1144494/).

What's a Rgs9-Cre/+;gtROSA/+ mouse? (http://www.sciencedirect.com/science/article/pii/S2212877813000719)


texts: Would a VR headset exacerbate myopia or could it be used to retrain the eyes?

texts:
I've learned that there are two primary hypotheses to explain myopia: not enough use of distance vision or not enough sunlight

If the distance between an eye and what it's focusing on is the primary cause, then having a VR screen inches away would seem like a recipe for exacerbating myopia.

However, since people with 20/20 vision can use VR headsets, while others need the maximum correction and still see everything out of focus, clearly there is something more than at play than simply focal distance between the eye and the screen.  Could this be used to help minimize, prevent, or possible reduce myopia?

Likewise, if the cause is primarily lack of sunlight, could sunny simulations be used to help minimize, prevent, or possible reduce myopia?  Or is the light produced too artificial?

Knowing that myopia is on the rise, and VR is going to be more prevalent in the near future, these seem like important relationships to understand.

Of course, it could be they are simply two factors of many; but they are extremely relevant to this question.

More recently, my ophthalmologist was adamant that I needed to follow the 20/20/20 rule, i.e. every 20 minutes focus on things more than 20 feet away for at least 20 seconds, which leads me to believe he at least subscribes to the distance hypothesis.


texts: If a DNA letter is one of A,T,C and G, and there are 3 billion base pairs, why don't we say that there are 6 billion letters in the genome?

texts: A DNA letter is either one of A,T,C or G. Human genome is supposed to have 3 billion base pairs coming from each parent. But these are pairs - a combination of A-T or C-G. So, doesn't that make the total number of DNA letters from a single parent, equal to 6 billion ?


texts: I just got struck by curiosity now: Intuition says no, but I've never had confirmation of it.


texts: Cellular respiration, why double membrane in mitochondria and not bacteria?

texts: Bacteria perform cellular respiration across a single membrane, their plasma membrane. What are the benefits of having double membranes in eukaryotes (in the mitochondria), and, how do bacteria achieve the proton gradient?


texts: How effective are restriction enzymes in protecting bacteria?

texts:
Bacteria use restriction enzymes to cut DNA of bacteriophages. Virus mutates really fast. Won't a point mutation in restriction site render the restriction enzymes of the bacteria useless ?

So how effective are restriction enzymes in protecting bacteria ?


texts: How a nerve impulse reaches the correct destination?

texts:
Say your brain wants to retract your right hand.

If there is some information coding playing a major role here, then what is the mechanism to find the correct path to reach the correct muscle?

Or is it every part has a single nerve connecting to the brain?

Any difference when it comes to withdrawal reflex comparing to brain initiating action? i.e. how the reflex round trip reaching the correct muscle?


texts:
I am working on phylogeography on one model species and I am a beginner. You can imagine one species that came on locality more than 5 mya (million years ago). It was a good environment, so the species expanded very quickly. After climatic changes this model species split in two refugiums (isolated locations for a once widespread species) and evolved into two species. This happened several times and now we have from that one ancestral species six valid species.

I have data from MrBayes and BEAST molecular clock. Can you recommend some phylogeographical program which can consider also expansion and contraction of model species?

My input data:

molecular identification (sequences)
coordinates (lat, lon) for each species
geographical data of a continent (altitude, precipitation etc.)

My goal:

Create a map where will be polygons (areas) of each species. These areas will expand and contract (step-by-step not like a do not want create video).

My problem:

I am able to make polygons by MCP, or kernel density, but unable to incorporate barriers into model. For example, polygons of species which lives in mountain region created by MCP include areas of lowland inside...


texts: I spotted this bird in India a day ago in a park located inside a city. There are no nearby water bodies around the park. The bird is slightly larger than the average person's fist. Does anyone know what species of bird is it?


texts:
I've often heard that a population, human or otherwise, will continue to grow as long as there is food available (assuming nothing else is killing them off).  It makes sense: if you have food you can live, and if nothing is hunting you you'll survive to reproduce.

I recently designed a piece of software to simulate an ecosystem, with groups of creatures of different species eating and hunting and reproducing alongside each other.  It was very simplified (each animal had simple attack/defense/speed/stealth values, etc), but something became rapidly apparent: in every simulation the predators overwhelmed the prey, reproducing until their numbers could not be sustained by the herbivores, and leading to an inevitable die-off of both groups.  I could delay the die-off by adjusting different values and initial population counts, but it would always happen eventually.  The predators would eat and breed and eat and breed until the entire system collapsed.

At first I thought it was just the product of my over-simplified system, but it got me thinking: what prevents predators from overpopulating in real life?

It seems like the natural tendency would be for (for example) the sharks to continue breeding and eating until all the fish are gone, or the wolves to eat all the deer, etc.  Obviously some predators have predators of their own, but that's just putting off the question: if the hyenas don't overpopulate because the lions eat them, then what's keeping the lions from overpopulating?  I can't come up with anything that would prevent the apex predators from growing too numerous, then fighting each other over a dwindling prey population, then dying off entirely when there was no more food to find.

Do predator populations self-regulate to prevent putting undo stress on their prey populations?  Or is there some other mechanism to keep the predator hierarchy from becoming top-heavy?


texts: Why are most transcription factors enhancing the expression rather than repressing?

texts:
One can classify the effects of Transcription Factors (TF) on gene expression into two types: it either enhance or repress the gene expression.

I have always been told that most of transcription factors functions act to enhance gene expression rather than repress gene expression. Assuming this is true, my question is why are activators more common than repressors?. Is there for example a mechanistic explanation for that (cost less energy to enhance or the enhancement pathway is easier to evolve)?

From wikipedia

  While activators can interact directly or indirectly with the core machinery of transcription through enhancer binding, repressors predominantly recruit co-repressor complexes leading to transcriptional repression by chromatin condensation of enhancer regions.

The mechanisms are different and it sounds a likely cause of the overrepresentation of enhancement function of transcription factors in genomes but it is not obvious to me why activators and repressors have to have use different mechanisms and it is not obvious to me either why these different mechanisms would yield to a ratio of repressors to activators other than $\frac{1}{2}$.


texts: What is the significance and method behind Ramachandran plots?

texts:
My PI showed a Ramachandran plot in class today with minimal explanation, but I'm interested in finding out more. I understand that the Ramachandran plot shows the relation between the omega phi and psi angleson either side of an amino acid alpha-carbon, but there are a few further points I'm confused about:

a.) What do these angles describe? Are they just dihedral angles that show translation around the bond-axis?

b.) Why are these angles important beyond the scope of identifying a secondary structure? Can they be used instead to identify the amino acid components, or only higher level structural units?

c.) What kind of instrument is used to collect the data and how are angles on either side of a single alpha-carbon correlated?


texts: How do you break up cell clumps when passaging?

texts: I am working with HepG2 cells, and they really like to form clumps.  Pipetting up and down in TrypLE does not seem to be very effective in breaking them up.


texts: What are the sites of nutrient digestion and absorption in the human GI tract?

texts: Where does nutrient digestion and then absorption take place for different nutrients along the alimentary tract?


texts: Can humans distinguish light having the same color but different spectrum?

texts:
Can humans distinguish light sources that have the same color in RGB space but having different spectral composition?

I know one method, that is when the light is producesed by monochromatic laser, it looks "grained" due to interference, but this is a shape-based indicator. What about indicators not based on the visible shape, just on color perception?


texts: Can there be an equilibrium between humanity's increase of carbon dioxide output with plants since plants harness CO2?

texts: Is it possible that, prior to hitting a thermal equilibrium in the atmosphere, the increase in CO2 that humanity puts out every year will come to an equilibrium due to the consumption by the world's plants, which may respond by growing, reproducing and feeding more off of the additional CO2 in the atmosphere at a faster rate?


texts: How do I read a species description that uses both ≡ (triple bar) and "incl." to denote synonymy?

texts:
I'm trying to understand the relationship of plants formerly classified as Dorstenia crispa with distinct individuals continuously classified as Dorstenia foetida. I would assume that the distinctive phenotype would warrant a var. or forma, if not a subspecies, but I haven't seen it written as such anywhere.

I turned to monographs, which in one case stated:

  incl. Dorstenia crispa Engler (1898); ... incl. Dorstenia crispa var. lancifolia Rendle (1915) ≡ Dorstenia foetida ssp. lancifolia (Rendle) Friis (1983);

Would this indicate that a specimen identified as D. crispa is properly identified no more specifically than as D. foetida?
Does this indicate that a specimen of D. crispa v. lancifolia is properly D. foetida ssp. lancifolia; or simply recognising that D. crispa v. lancifolia and D. foetida ssp. lancifolia would refer to the same individuals, which are properly still called nothing more than D. foetida?
Since these formerly-recognised infraspecific taxa do exist as separately-kept lines in cultivation, would they be properly recognised as cultivars?

My answer may simply be the closing remark in the above-quoted description, "Since the various forms are connected by intermediates, it is impossible to recognize infraspecific taxa." However, that's deeply-unsatisfying if cataloguing a collection that contains several now-synonymous specimens.


texts: How Do Large Ocean Viruses Form Their Own Organelles?

texts:
Several large viruses (Arslan 2011) form their own organelles within the amoebae they invade.

How do these organelles form?

Reference:

Arslan, D., Legendre, M., Seltzer, V., Abergel, C., Claverie, J-M. (2011) Distant Mimivirus relative with a larger genome highlights the fundamental features of Megaviridae. PNAS 108(42): 17486-17491 [DOI]


texts: If there is ample amount of food, do C. elegans worms know when to stop eating or do they store extra energy? Could they put this extra energy to use by moving faster or putting more eggs?


texts: Degree of dosage compensation in Drosophila melanogaster

texts:
In this paper the authors state that the dosage compensation seen in Drosophila is approximately twofold, but they do not provide any source or numbers (as far as I can see) for this. What is the mean degree of dosage compensation in Drosophila (melanogaster)? For example, if X linked genes are, on average, perfectly upregulated the X:AA ratio in males would be 1, while if they are nearly perfectly (but slightly under) upregulated it will be ~0.9.

Here is a similar (but different) question RE perfection in DC in general (here I am specific to Drosophila melanogaster).


texts: small airborne microorganisms, are in many instances attached to bigger particulate substances?

texts:
From https://biology.stackexchange.com/a/90193/56476

  very small airborne microorganisms, are in many instances attached to bigger particulate substances in the air, whether liquid micro droplets or solid particles. ... but this may be reason for higher risk of respiratory infectious diseases when PM2.5 air pollution gets high.

Can someone confirm this great logic?

I think it is true, but just need a confirm from the public! :)

Many thanks.


texts: Why does BLAST reduce word size for short proteins?

texts:
I'm using BLAST to identify a short protein (BLASTp). If I check the short query then the word size reduces from 3 to 2. However the search will then be less reliable right? Because reducing the word size increases the chance of finding matches? So my instinct would be to raise the word size to almost the whole length of the query, because with a short query you want to search really specific to reduce output results, so apparently I'm missing something.

So I hope someone can explain me why reducing the word size from 3 to 2 is better for short proteins while using BLASTp


texts: How does coffee cause calcium loss in our body?

texts:
Recently on radio a doctor advices to reduce the consumption of coffee as it leads to calcium loss(as my mother described). My initial response was: How could such thing be possible? What kind of experiment have been done to assure that the coffee is the cause and not something else? But then I found this article on internet, though it doesn't go into depth of the topic. So I'm wondering :

How does coffee cause calcium loss?
What is the related chemical reaction?
Does it just happen in intestine or elsewhere in the body?
What amount of coffee consumption would make it severe?


texts: What is the transcriptome in layman's term?

texts:
I am new to the bioinformatics field and am trying to understand a research paper that includes some terminology without definitions. The term transcriptome in particular is banded around in the literature, but is not clearly defined.

Can someone provide a reference or source to guide me to some learning material where I can get the basics.


texts: How does TYRP1 affect the synthesis of black and brown eumelanin (on a biochemical level)?

texts:
TYRP1 (aka B-locus) is a gene in dogs that determines whether black or brown eumelanin is produced (assuming eumelanin is produced at all which is determined by the MC1R gene). I've looked at many papers and flow charts and now i have a contradiction: DHI seems to be the molecule that gives eumelanin a black color and DHICA a brown color. According to many flow charts, TYRP1 seems to be involved in the polymerisation of DHICA (not DHI). Mutations that cause a loss-of-function of TYRP1 will cause dogs that carry these mutations (homozygous) to have brown fur. But if TYRP1 is important for polymerisation of DHICA to brown, why does a loss-of-function of this very protein cause dogs to have brown coat color?

Where did I get it wrong?


texts: How is the exogenous DNA protected from degradation during bacterial transformation?

texts:
During transformation, a bacterium can take up DNA from its environment. A small fraction of bacterial species are known to be naturally competent, meaning that they can engage in this sort of horizontal gene transfer in their natural environments.

As I understand it, naturally competent bacteria carry genes that encode the machinery necessary to facilitate the transport of this DNA across the membrane and into the cell. The exogenous DNA binds to a receptor located on the surface of competent cells, gets fragmented into small pieces, and then one strand is degraded while the other strand is transported across the membrane into the cytoplasm with the aid of a DNA translocase enzyme. Ultimately, assuming a sufficient degree of homology, it incorporates into the host genome via recombination.

During this process, however, the DNA has to be protected from degradative nucleases. I remember reading something about a transformation-specific DNA binding protein that coats the entire length of the DNA strand and prevents degradation. Is it the same translocase enzyme that facilitates movement across the membrane that is responsible for this? Or is there another protein involved?

And then, regardless of which protein is responsible in the case of natural competence, how does that protein get expressed and activated in the case of artificial competence? When we induce competence in the laboratory through one of various methods (e.g., electroporation), the DNA is essentially forced into the cell through openings in the membrane, so no transferase protein is needed. What signals the bacterium, then, to express the protective binding protein? What keeps the exogenous DNA from being readily degraded by endogenous nucleases? Whatever signals induced the expression of this protein in the case of natural competence would seem to be absent when competence is induced artificially, and it doesn't make any sense that the bacterium would constitutively express such a protein.


texts: What is meant by a muscle fiber being glycerinated?

texts:
I was popped this questions today, "what is a glycerinated muscle fiber, and what is required for its contraction," and had little idea. I'm assuming the question is "what's required for its contraction as compared to normal muscle tissue?"

There's a limited amount of information out there about this. It appears that it is a type of in vitro system requiring special preparation of typical muscle tissue. I was wondering if anyone here had a little more information. Is this something that's just used in teaching lab exercises?


texts: Osmotic pressure and turgor pressure details

texts:
I am a high school student and I am very confused in how we define osmotic pressure?
Osmotic pressure is defined as the pressure required to stop the diffusion of solvent into a solution by applying external pressure over solution, which means that when the pure solvent is diffusing into the solution then it will apply pressure on the semi permeable membrane and when we have applied the same external pressure over the solution then there is no net movement of solvent occurs across the membrane and mathematically it is equal to P=cRT, where c is the concentration of solution , T is temperature in kelvin and R is the universal gas constant, if we go by this equation and calculate the osmotic pressure of 1 molar concentrated solution at room temperature it comes out to be almost 2495Pa which means 2495Newton/m^2 which is very high pressure and it doesn't seem to be true as osmosis is very slow process it surely cannot generate that much of pressure( just to imagine how large is that pressure assume an area of 1m^2 and place Mass of 249.5kg on it), so I think that it should not be that higher, so ,I am unable to understand what is actually osmotic pressure ,on which does it actually act and how do we actually calculate it?
we say that when a cell is placed in hypotonic solution then osmotic pressure is greater than Turgor pressure and water will flow inside the cell, but I have a confusion that like turgor pressure acts on the wall of cell ,osmotic pressure should also act on the wall and in opposite direction of turgor pressure, so by this logic wall should compress more as osmotic pressure on it will cause it to compress and turgor pressure will cause it to expand but Osmotic pressure is greater than turgor pressure it should compress, but it doesn't happen? we only talk of turgor pressure to explain the expansion but not osmotic pressure why? I know I am going wrong somewhere if Osmotic pressure would really leads the cell to compress then an animal cell would have never burst in hypotonic solution. and if osmotic pressure is also acting on the wall or membrane then net pressure on the wall is O.P-T.P (in inward direction) , and not only T.P (outward) so the wall pressure here also should not be same as turgor pressure?
If anyone will explain me this by giving as many examples as possible than it would be very helpful for me to understand because its my first time I came to know about these things.


texts:
Can anyone give me some explanations on number 2 and 4?
I thought that they're epidermis and collenchyma with #1 as cuticle.
But the key says they're collenchyma and parenchyma. I'm confused.


texts: Do Yersinia genus spp have anything movement factors?

texts:
It can spread in blood (Type III secretion system -> apoptosis).
I am interested if there is any others ways to move.

Do Yersinia spp have anything virulence factors to move?


texts: Is studying complete mitochondrial genome need biological lab work?

texts:
The research complete mitochondrial genome study done on species:

Juema pig Sus scrofa (Suina: Suidae) from southern Gansu
red rainbowfish
speckled dace, Rhinichthys osculus
white char Salvelinus albus (Salmoniformes, Salmonidae)
Himalayan honey bee, Apis laboriosa

Did they need to do any work in biological laboratory?

More specifically, Are they related to bioinformatics completely?

Most of them just wrote length in bp (base pair), percentage of ATGC and several combinations of them and some special behavior. These seemed to me as expressing some statistics.

So, how could it be a research work?


texts: Listing Cluster of Differentiation (CD) markers (immunology)

texts: I hope this question is appropriate for this SE. When listing multiple cluster of differentiation (CD) markers to define a cell population, e.g. CD3+CD8+CD45+CD4-, is there a default order to put them in? I was recently told to list them numerically with the negative populations after the positive ones (i.e. CD3+CD8+CD45+CD4-). However, I have seen different orders in the literature and would personally prefer to order them by whatever I would consider most logical (e.g. CD45+CD3+CD8+CD4-).


texts: What features cause mechano sensory adaptation?

texts:
In relation to mechanoreceptors (e.g. pacinian corpuscles), what stops a constant stimulus from producing action potentials?

I understand that adaption is used to filter out stimuli that aren't changing, but what are the cellular mechanisms going on within the neurone that drive this process?


texts:
What can you conclude about the risk (with each pregnancy) that a couple could have a child affected with an autosomal dominant disorder if...

One parent is affected (heterozygous) and the other parent is unaffected.

I did a punnet square and concluded it was 50 percent because half were Aa and half were aa.

But a classmate told me to line up Aa and aa and conclude that there is only a 25 percent chance that a child is affected because there is only one capital or dominant A and three are "a".  Which do I do?


texts:
As far as we know Ape Men or the Neanderthal Man was the first to bury its dead. My question is why.

I don't think they practiced religion or believed in spirits or faith or stuff like that. Therefore what was their main reason to bury their dead in the first place?

(Also correct me if I'm wrong but i think that religion only emerged after Homo sapiens came to be.)


texts: What is the name of this spider I found in The Netherlands?

texts:
This spider is smaller than 1 mm and fast.
The spider has tiny hairs on orange coloured legs. The backside of the spider is dark-brownish and has a small red stripe in the middle. I have taken pictures magnifying 25x using a lens of some watchmaker glasses. As a reference the lens of the lamp shining on the spider is 6mm.
Found inside my house on the second floor on the attic.

The location is North-Brabant, The Netherlands, location on maps.

I have searched all over the internet but I keep coming back to mites which this specimen doesn't resemble.

Unfortunately the camera isn't as good as my eyes, although a little zooming is possible.

The spider skittered around again today and I managed to take a picture, unfortunately not a zoomed one but maybe some characteristics will be recognized.


texts:
During intracellular proteins synthesis, all proteins are made by free ribosomes in the cytoplasm and some, but not all ribosomes (those which make membrane or secretory proteins) move to the endoplasmic reticulum (ER) and attach to it during translation (called co-translational transport).
Why are proteins that will be exported to the outer of cell are not made in the ER directly?
What is the function of ER in intracellular protein synthesis?
What is the purpose of co-translational transport?


texts: What is the advantage of using starter cultures for growing bacteria?

texts:
Many DNA isolation and protein expression protocols contain instructions to use a starter culture of E. coli that is then used to inoculate the main culture.

What are the advantages of using starter cultures compared to just let the bacteria grow in the same medium for a longer time? When should one use starter cultures and when can one safely skip that first culture?


texts: Making Cupriavidus metallidurans in laboratory?

texts: This is probably a stupid question but would it be possible to 'make' Cupriavidus metallidurans? And if so how? I'am guessing it wouldn't be possible without the use of expensive equipment for genome sequencing.


texts:
What is a positive epitope fragment? I found one paper on the subject:

COBEpro: a novel system for predicting continuous B-cell epitopes by
Michael J. Sweredoski and Pierre Baldi


texts: Regarding the apoptosis mechanisms in cells and cancer

texts: If all the cells in a cancerous tumour had their apoptosis mechanisms 'turned back on' or reactivated or repaired by some 'yet to be discovered' process would this cause the tumour to 'self destruct' or be destroyed? Are there known processes that can repair or reactivate the apoptosis mechanisms in a cell?


texts: Quick and useless question : what can be the longevity of a cut strand of hair, assuming we kept it in (good) normal conditions ? Any idea ?


texts:
Is there a reason as to why chickens lay "egg" shaped eggs, as opposed to spherically shaped eggs (or a random shape)?
For extra points:

why do plant seeds often come in this same "egg" shape (e.g. avocado
seeds), as opposed to a sphere?  Is it a coincidence that avocado
seeds and eggs are the same shape?


texts: Is there any disadvantage to having a really low adipocyte count in our times?

texts:
The key feature of adipocytes seems to be energy storage. Today humans in Western countries don't have to hunger and have therefore less need to store energy in fat cells.

Do adipocytes have additional functions that still make them valuable?
Wikipedia lists 10–13% and 2-5% for men as essential body fat percentage for woman. What functions don't get fulfilled if the body fat percentage drops below that level?


texts: Identify fuzzy black quarter sized spider with orange on abdomen, in Minnesota

texts: Found this spider on my car in Minnesota near St Paul (USA). Total size including the legs (end of rear leg to end of front leg in picture) is probably about the size of a quarter.


texts: Can I grow unlimited stem cells from limited embryonic stem cells?

texts: If I theoretically extract a few embryonic stem cells from the embryo and cultured in vitro with enough nutrient to grow more cells. How many maximum of stem cells can I get?  Do I need to add any compound to inhibit the differentiation progress?


texts:
My daughter asked a question that I could not answer.

If you have a cold, you have symptoms such as fever, cold and sore throat. These symptoms, however, are the reactions of the immune system to bacteria, viruses and other germs.

So my question is: What would happen if the immune system did NOT respond? I know that bacteria can produce certain poisons. And viruses can capture human cells and make them produce more viruses.

Now to the naive part: But what's wrong with that?

Are Viruses dangerous because these cells would then no longer perform their function?
Without any immune system: Would a virus simply take over all human body cells?
Is it not the organism in the first place, who puts itself in mortal danger (such as high fever or inflammations) because of the defense reaction?

Thanx!


texts: What are the physiological effects of retinal exposure to 380–400nm light?

texts:
There are two categories of sunglasses: UV380 sunglasses block all light with wavelength 380nm or lower, while UV400 sunglasses block all light with wavelength 400nm or lower.
This made me wonder, what are the physiological effects of retinal exposure to the 380–400nm band of light, which is not covered by UV380 sunglasses?
Also, assuming that the 380–400nm UV light does cause eye damage, does any potential pupil dilation caused by the dark tint of such glasses have an effect on the amount of damage caused?


texts: Does the law of independent assortment apply to homologous chromosomes or alleles, or both?

texts:
My textbook is giving me two definitions

1st def: "random orientation of homologous chromosomes at the metaphase plate in meiosis 1."

2nd def: "alleles for one gene separate into gametes independently of alleles of any other gene (only if genes are on non-homologs or very far apart on same chromosome)."

It's kind of hard to explain but here are my thoughts on this:

It seems to me that the 1st definition is exclusively taking a look at each pair of homologous chromosomes:  It looks like it is talking about alleles on certain homologs themselves and how there's 50% chance that a gamete will get a paternal and maternal allele of a gene after anaphase I.

And I'm guessing that the 2nd definition is an extension of the first by comparing gene assortment in all the homologous chromosomes:
It looks like it is primarily talking about the genes that are on each pair of homologous chromosome and how they (the genes) separate independently of each other (because they are on different homologs) in addition to the "random orientation of homologous chromosomes".

Can someone please clarify?


texts: Dendrodendritic synapse through axodendritic synapse at same dendrite?

texts:
Reading Wikipedia's article of dendrodendritic synapse, I find that:

  Dendrodendritic synapses are activated in a similar fashion to axodendritic synapses in respects to using a chemical synapse. These chemical synapses receive a depolarizing signal from an incoming action potential which results in an influx of calcium ions that permit release of Neurotransmitters to propagate the signal the post synaptic cell. There is also evidence of bi-directionality in signaling at dendrodendritic synapses. Ordinarily, one of the dendrites will display inhibitory effects while the other will display excitatory effects.

Now I was wondering, does dendrodendritic synapse occur only when the neuron reaches the threshold action potential and "fires" or is it possible that dendrodendritic synapse occurs as a result of, for example, an axodendritic synapse at the same dendrite? (even though the neuron doesn't fire)

Edit

Clearly, we can see that the dendrite has multiple 'endings'. I was under the impression that a synapse can happen at any such 'ending'. Assuming that a synapse happens at one ending of the dendrite, is it viable that anything happens to a neighbouring neuron that is connected with a dendrodendritic synaptic connection to the other ending of the dendrite?


texts: What is the mechanism behind cats' geolocating homing behavior?

texts:
Some cats, which are separated from their home, have the ability to travel back to their original home - even over long distances and land that they haven't encountered before. E.g., see the Time article on the mystery of the geolocating cat or the following blog entry.

Based on the material above there seem to have only been some suspected mechanisms a few years ago.


texts: Confusion about mitochondrial electron transport chain Complex I Wikipedia article title

texts: The Wikipedia article title for Complex I (the NADH dehydrogenase enzyme complex) is "NADH dehydrogenase (ubiquinone)". This is confusing to me because this title sounds like ubiquinone is another name for NADH dehydrogenase, but ubiquinone is in fact the Coenzym Q, which is reduced by the hydrogen transferred from NADH through Complex I. What is the reason behind this title? I mean, what is the point of having "ubiquinone" in parentheses in the title?


texts: What was the point for us humans (or other mammals) to develop such a strong sense of smell? Depending on the source, we can distingiush from 10.000 to even trillions of smells. But how was the ability to sniff "artificial" smells (e.g. paint or burning rubber) being useful to our ancestors?


texts:
I had the following question on an exam of mine and I got it wrong, so I was wondering if someone could help explain the reasoning to me. Below I list my explanation.

  An overheated and sick dog in a hot environment will have an impaired thermoregulatory response when its

  (A) evaporative heat loss increases

  (B) metabolic heat production decreases

  (C) body temperature increases to match the environmental temperature

  (D) blood vessels near its skin increase vasoconstriction

So here's how I approached this: A and B are clearly incorrect, as they aid the thermoregulatory response of the animal by allowing it to lose excess heat.

Thus, it comes down to C and D. I chose D because I thought that since vasoconstriction traps more of the heat inside the body, it would be counterproductive to what the dog actually needs (vasodilation). I'm assuming that the correct answer choice is C, but could someone please explain it to me?

Thanks in advance to all who reply :)


texts: Do the eggs of fraternal twins come from the same ovary?

texts: With fraternal twins two matured eggs are released and fusion of the two with sperms result in formation of these fraternal twins. Then do the two matured eggs come from one ovary or both the ovaries at the same time?


texts: What animal's lower eye lid moves to upper one when closing eyes?

texts: I know cock's lower eye lids moves to meet the upper one when it closes its eye.  What other animals does this?  BTW, "cock-eyed" can mean upside down, I think.


texts: What happens to the holes in the skull where teeth were developing?

texts:
In Skeptics.SE, a question regarding the skulls of children arose. Depicting a scary skull where the permenent teeth are "hidden" inside the jaws and the milk teeth are in the their place.

After all milk teeth fall out, and the permanent teeth "rise", do the holes left by them filled up, or do we go around with holes in our jaws?

The question on Skeptics

The picture:


texts: Are there any bacteria that can receive ultrasound signals?

texts: I'm looking for an example of bacteria that could receive ultrasound (at any ultrasound frequency) signal and possibly perform some (re)action afterwards.


texts:
I want to chemically synthesize a GFP gene for expressing in rice.I am using the IDT Codon Optimization program and found that not all the codons are 100% optimized. Some of them are the 2nd or 3rd in frequency of usage. Also, the stop codon in the gene optimized is the least used in rice. I don't think all the codons can be the ones that are the most used in rice as there is need of translational pauses to get optimal protein expression. But how do I decide which codons are to be used in what positions to get maximum efficiency. Do I just use the automatic codon optimized gene given by IDT or further optimize it manually?

So should the stop codon used be the one which is the most frequently used in rice for proper mRNA termination?

Please help me as I am new to this and want tips and suggestions for getting optimized codons in this gene.


texts: Is there any study to find the plant with the absolute minimum light need?

texts:
Is there any study to find plants with absolute minimum light need?

Consider a bathroom without windows that you have occasional artificial light (e.g. white LED light).

Another question is there any numeric system assigning a number to each plant representing its minimum and maximum light tolerance?


texts: Can flow-FISH be used on metaphase cells?

texts: I know flow-FISH can be used on interphase cells but was wondering if it only works on interphase cells or can work on cells regardless of stage in the cell cycle.


texts: Loss of taste and smell during a SARS-CoV-2 infection

texts:
In France the loss of taste and smell (la perte du goût et de l'odorat) is considered as one of the key symptoms of a SARS-CoV-2 infection (although googling shows that it is considered less definitive elsewhere). What causes such a loss of taste and smell?
More specifically, an infection by SARS-CoV-2 is rarely associated with nasal congestion, so one cannot blame mechanical obstruction (and it would not apply for the loss of taste). One can then think of the virus attacking the relevant sensor cells or a less direct effect via disrupting the relevant metabolic chains. I will appreciate clarifications/explanations/references.


texts: Is this ladybird larva secreting a protective fluid?

texts: I know that adult ladybird beetles can secrete a fluid to keep predators from eating them. Can the larvae do that too? Or are these yellow droplets something else?


texts: How do biologists estimate that there is 8% of protein coding genes in human genome?

texts: In class, the professor said that there is about 8% of protein-coding genes in human. I wonder how biologists estimate this without annotating all of human genes. Thank you!


texts:
There is a region that gets about 812mm of precipitation and is mildly hot all year long.

I believe this region is a tropical savanna, but I'm not 100% sure.  Is this correct?


texts: Why are eyes more sensitive to flicker in periphery — contradictory answers

texts:
In terms of the perception of flickering by CRT monitors, This answer suggests that peripheral vision has faster response and is thus more sensitive to flicker due to being provided by rod cells.

But in another answer it's said that rods are saturated at daylight and even at twilight. These two answers are in contradiction, since the light from CRT mentioned in the question pointed to by the first link above is quite above the photopic threshold.

So, how to reconcile these two answers?


texts: Comparing the amount of domestic animals and wild animals?

texts:
From some material, I read about the ammonia (NH3) emission from animal waste.

I found that the emission from domestic animals are greater than wild animals.

Then, I can't help wondering the amount of wild animals and domestic animals(cow, pig, chicken, etc). Which has the greater amount on Earth? And how to estimate the amount approximately?


texts: Are Whales More Intelligent Than Humans?

texts:
Are Whales smarter than Humans?
Their brain size leads me to think so.


texts:
Living in northern latitudes, I have always wondered why do migratory birds invest so much time and energy to travel twice a year the vast distances between their breeding grounds and wintering areas. The most commonly found explanation, and the one I am grown accustomed to, is the scarcity of resources, resources meaning food and nesting places.

For years I have considered this a quite convenient explanation but recently I came to rethink it.

As you know, many of the longest migrating birds are insectivorous such as European Pied Flycatcher that breeds in much of Europe and western Asia but spends winters in western Africa. While it is easy to see the scarcity of food (insects) in northern breeding areas during winters, it is more difficult for me to see the scarcity of food in southern wintering areas during summers. - Take, for example, ants, that I expect, are abundant in those places all year around. Considering their total biomass, they would seem to hold a potential for a stable food source for masses of insect eaters with minimal food gathering effort required. So why migrate?

Is it that ants (or any other seemingly overly abundant invertebrates such as termites and mosquitoes) are not nutritious enough? Or are they too stingy and poisonous perhaps?

As for nesting places, I am aware that many birds defend their home range (thereby setting an upper limit for population density), but I imagine that such behaviour could be subject to change (or never had emerged in the first place) if there was no need to compete for other resources (mainly for food).

Or are the primary constraining factors disease and predation that would follow from a larger population density?

So in short, my question is, what is (/are) the primary reasons(s) for insectivorous birds to migrate instead of staying in their wintering areas and feeding on (seemingly abundant) local resources such as ants?


texts: Is "A" inhibiting "B" and vice-versa, a positive feedback loop?

texts:
If product A inhibits the expression of product B, and product B inhibits the expression of product A, is this a positive feedback loop?

My thinking was to consider the scenario that A starts off high, and so B is naturally low. Then, a large amount of B is added to the system. This inhibits the production of A, so the level of A falls, and that in turn enables the production of more B, which further decreases the production of A and in turn further increases the production of B, in a never-ending cycle. This runaway amplification is characteristic of positive feedback loops, whereas negative feedback loops cause a return to equilibrium.

Yet the Wikipedia page says that, for it to be a positive feedback loop, it must be set up so an increase in A causes an increase in B.

So what is it?


texts: Typical firing patterns of (some) motor neurons

texts:
Since it is not so easy to imagine and visualize the behaviour of the muscles in the fingers, hand, and arm of a violinist performing a fast and accentuated trill vs. a slow and soft vibrato, I try to imagine and visualize how corresponding motor neurons do fire.

I assume there are some motor neurons that are immediately responsible for the speed and amplitude of the movement of a finger performing a fast trill, and — partly the same, partly others — that are immediately responsible for the speed and amplitude of the movement of the same finger performing a slow vibrato.

The behaviour of these motor neurons — during the trill or the vibrato — can be recorded as corresponding sequences/trains/bursts/chats of spikes.

I wonder:

  How may these spiking and/or bursting patterns look like?

Maybe like this?

fast and accentuated (= large amplitude) TRILL, each group corresponding to one movement (up-down) of the finger

slow and soft (= small amplitude) VIBRATO, each group corresponding to one movement (to-fro) of the finger


texts:
I've been trying to figure out what makes the vitamin B group really big with 8 vitamins.
Chemically they have different structures.
Solubility: not only vitamins from this group are water soluble vitamins (also vitamin C).
Function: not only this group of vitamins are cofactors for metabolic processes.

So what's the reason for this grouping, or why we can't include other vitamins in this group?
Also, what does the letter B stands for?


texts: Does TSH and Growth hormone have any role in menstruation?

texts:
Actually, I came across this on a mcq (multiple choice question) exam:

Name the hormone which has no role in menstruation:

A. LH

B. FSH

C. GH

D. TSH

(only 1 correct option)

Both FSH and LH have direct roles in the menstrual cycle, they're responsible for the follicular phase and ovulation, respectively. Menstruation takes place due to the decreased levels of progesterone. Does GH and TSH have any role in the process? If so what is that role?


texts: Health effect of electromagnetic and acoustic waves on brain function

texts: What if any effects are there on brain function from prolonged exposure to electromagnetic or acoustic stimulation?


texts: To what group does coconut plant belong?

texts: I've tried looking it up but I couldn't find an answer. Could someone please tell me to what group of plants do coconuts belong depending upon the natural availability of water?


texts: Source for 'EVERY living organism uses ATP as energy carrier', and can we make a synthetic one that doesn't?

texts:
I have read it repeatedly that 'all living organisms use ATP as an energy currency etc' and 'some use GTP in addition'. However I am yet to find a reliable resource, rather than just quora/reddit/researchgate posts, that states this.

Also, would it be possible to create a synthetic organism which does not use ATP? Or GTP? What might be the best energy currency to use then?


texts: Terminology for inefficacy of selection on recessive alleles

texts:
I am wondering is there some proper terminology which is used to say that deleterious recessive alleles might be able to hide, reducing the the efficacy of selection, in diploid organisms/chromosomes.

I was thinking about Y chromosome linked mutation and their inability to hide from purging by selection behind other alleles by being recessive... perhaps something like recessive sheltering? e.g. "In the Y chromosome mutations are more easily purged because recessive sheltering does not occur" ?


texts: Why do house geckos take so long to react?

texts:
This is the Common house gecko found abundantly where I live.

I've been observing this for quite long and I used to ignore it after thinking on it for a short while. Today I decided to write this here on Biology SE.

So in my lawn there's this large wall on which there are usually around 3-4 geckos foraging for their favorite insects in night. Everytime I walk towards them some of them instantly go into their hiding spots (within 1-2 seconds of my arrival) with lightening speed. But most of them initially look cool and not actually bothered by my presence. Not only that -I can even wave at them; go closer towards them and nothing happens. But suddenly after all of my actions they also run towards their hidings as they were daydreaming. (Though not instantly)

Just curious-

Is there any real lag between their signal reception and processing?

Are there some other animals which show such behavioural responses?

(Maybe they are just kidding with me :P)


texts:
After reading about slime mold I was wondering, do slime mold simply expand outwards or multiply?
e.g. if I put 100 grams of slime mold in 1 location, will it expand to say, 2 locations, and have the 1st location with 80 grams left, and 2nd location with 20 grams (i.e total 100 grams), or is it that they multiply; 1st location still 100 grams, and 2nd location with 20 grams?


texts: why finger of hands and feet become wrinkled due to to water?

texts: Mostly due to bathing or washing clothes our finger become wrinkled what was the reason behind it??


texts: Finding protein motifs by running sequence analysis in protein BLAST

texts:
I've run the following sequence (bottom of page) in NCBI protein BLAST and its been identified as Zn-dependent alcohol dehydrogenase. Next I want to see what protein motifs are in this protein. Where in the programme is it possible to see the motifs?

Thanks in advance!

Sequence:

MDRNRLAIVFPIFARCISAADFSTDLYLSEIYQQKVVTMKAAVITKDHTIDVKDTKLRPLNYGEALLEIE
YCGVCHTDLHVKNGDFGDETGRISGHEGIGIVKQDGEGVTSLNAGDRASVAWFFKGCGHCEYCVSGNETL
CRNVENAGYTVDGAIAEECIVVAEYSVRVPDGLDPAVASRITCAGVTTYKAVKVSQLQPGQWLAIYGYGR
FRQSSPSICQDMYFNAKDEQLAYYAKELGGADMVINPKNEAAKIIQEKLGGAHATVVTAVAKSAFNSAVE
AIRAGGRVVVVVAVGLPPPEKMDLSIPPRLVLVGIEVLGSLVGTREKEAFQFAAEGKVKPKVTKRKVEEI
NQIFDEMEHGKFTGRMILPTHHIWIVIGWQSFSLYSQDVSQPQIFRLTSISPRYINKRSPKQPSLLKIIR
STKTPNYALITGKRFWKSNIAGYVIPISMKTGISAMKPAEFQGMKVVSSSRTGKGLLLMPVTAPVLHGSS
KAAAIANIVSAGMKRFAATLKMPVIRLTALQKNASSSPNTRSACQMVLILRLPAGSLARVPPIKQRFLSY
SPDNGWPSMATGGLGNLALRYAKTCISTPKMNSSHTTPKSWAAQIWSSIRKTKLPKSFRKSSGEHTRRWR
LLPNPPLTRLLRLSARVAVLLLLSPLVCLLLKKWIAFLLVWCLSVSKSVPWSERGKRRPSSLQPKVRSSR
KLPSVKSKKSTKSLTKWNMVNSQAVYYQPITYGSSAGNRFPYIRKMYLSRRFFDPLSLRDISTKGSHHES
SRHYRSYDRRERHQITPSELRGSASGNRILRGMSYRSPCEKRGFRRNRQNFRARYRYRQAGRGRGYFSEC
RPRQCCMVLQRLRPLRILCQRENALPQRKCRLYGRRYSRRMHRRRRILGPRARWSSCGCQQDHLRGCNHL
SSKGFSATARTMAGHLWLRAVAIPFDMETPRHVFQRQRTARILRQRVGRRRYGHQSEKRSCQNHSGKARG
STRDGGDGCCQIRLLGCGYPRGWPCCCCCRRWSASSKNGFEHSSSFGACRYRSPRFLGRNAGKGGLPVCS
RRGQAESYQASRRNQPNLRNGTWIHRPYDITNPSHILYVMGWYHTACEFTMFHFVKDLVDFFDFTLGNFR
LDLTFGCKLEGLLFPRSDQGTDFDTDKHQTRRNAQIHFFRRRQTNGDNNNNTATRADSLNSRVKGGFGNS
RHHRRVCSPELFLNDFGSFVFRIDDHICAAQLFGVVCELFIFGVEIHVLAYRRARLPKPPVAIDGQPLSG
LLRNLYCFIGGYTRASDPAGNRRIKTIWHADRVFGDDDAFFCYSAVNRITGIFNVAAKRFIPADTIFAMA
AAFEEPCNTGAVTGIQRSNPFPVLLDDTYTFMPNSAGFIAEIPVFHMEIGMTYPAIFDFQKRFPVIQRAF
GVFHVDRMIFSNDGCFHGDYLLLIYLGEIEVSRKICGDTSCEYRENDCQPITIHYMWVGNIIRPVNLPCS
ISSKIWLISSTLRLVTFGLTLPSAANWKASFSRVPTKEPRTSIPTSTKRGGMLKSIFSGGGRPTATTTTT
RPPARIASTAELKADLATAVTTVACAPPSFSMILAASFFGLMTISAPPNSLAYASCSSLALKYMSWHIEG
LDCLNRPPMASHCPGCSETFTALVVTPAQVILLATAGSRPSGTRTEYSATTMHSSAIAPSTVPAFSTLRQ
SVSFPLTQYSQWPQPLKNHATLARSPAFREVTPSPSCLTIPIPSCPEILPVSSPKSPFFTWRSVHTPQYS
ISRSASPFRGRNLVSFTSIVSLVMTAAFMVTTFCYISERRSVEKSAAEIHLANIGKTIASRLRSICDGLV
ISYGLIYHVPFRQRFGFLRLYAWLSAPYLRLQTGRPPFPAFRPRNLGLRYRQAPNEEECSNPFFQEEADQ
RRQQQQHGHPRGPQQPSRRIWQQPSPPSRVLPRAFPEFWQLRFSDPYLRRPTLWRSMRAVHLWRNTCLGI
SKGIATARSHRWPAIVRAVAEKPLLLYRWLHPRKSCWQPQDQDHLARGPSIRRRRCILLLRRQPYNRHFQ
RCGKAFHSRHNIRNGRSLRTMQHWRGHRHSEKPLPRPARYLYLHALKFCRFHRRNPRFSHGDRYDIPRNI
RFPEALPRNSEGVIWCLSRRSYDLRLLSWLPFVDISRRDRGQSKNLRLRYILRIGKRLPADYDP


texts:
I was examining some rainwater from my backyard in Richmond, VA, and found this microorganism. I took some pictures of it at 400x and 1000x (see below). The microorganism is attached to some moss and appears to be using it as an anchor while hunting/feeding. While feeding, it stretches out and searches for food, and once it catches something, it snaps back into itself. I also got some pictures of the microorganism while resting.

I'm not sure what this is and would appreciate any input. Thanks!


texts:
I have seen the spinal cord and it's a white, soft, slippery cylinder that has a small diameter (about 25-30 milimeters). It absolutely doesn't have a macroscopocally reticular texture that would allow us to track down individual pathways. Same goes for the brain, it's also not macroscopically reticular and yet we know a lot of connections inside the brain.

So what's the technique used to discover these neural pathways and the information about in which parts of the pathway are synapses located?

Example of what we know is here under the "Major neural pathways" title.


texts: How long can you effectively store a glycerol stock at -20 degrees Celsius?

texts: I know that glycerol stocks are typically kept in a -80 °C freezer, however there are some people who do not have access to such equipment. How long would you be able to keep a glycerol stock at around -20 °C (typical household freezer temperature). I would like to create a new stock before anything goes amiss.


texts:
I understand this is not a biological question but this is often a problem whenever I look for literature.

How to look for a reference for some fact based on keywords. For instance you know about a fact such as - Cell signaling responses are faster but short lived compared to transcriptional responses. How to find the literature which actually says this. I often end up getting irrelevant results.

In other words, how to represent a fact using appropriate keywords. Is there an algorithm which can generate synonymous statements [like MeSH terms in pubmed] and search for those.
Or is there any way of setting up a hierarchical search.

PS: If someone finds a reference for "Cell signaling responses are faster but short lived compared to transcriptional responses" then please let me know


texts: Is this an Emperor Penguin or a King Penguin?

texts:
I have a book from Dorling Kindersley called Animal Encyclopedia (the German version that I have is called Das große Tierlexikon) with images from animals.
One is titled Emperor Penguin (Kaiserpinguin) which is in my opinion clearly recognizable as a King Penguin (Königspinguin).
This is the image:

I wrote to Dorling Kindersley and they told my that their investigation revealed that it really is an Emperor Penguin.
I am not a biologist nor a penguin expert, but from all the descriptions and images I could find (even in the same book on other pages!) I think the publishing company is wrong and just too lazy or arrogant to admit this error and too miserly to release a revised version of the book.
Who is wrong? Me or Dorling Kindersley? Emperor or King?
Update 2020
They seem to inherently admit it themselves, that the book was wrong (and that they lied to me), as they used the same picture on one of their websites and with king penguin in the caption of the picture:


texts: Which agricultural crops attract rodents?

texts: Are there any data on rodent populations per acre of different types of agricultural crops?


texts: Why do molecular generation models maximize "penalized logP" as a measure of drug-likeliness?

texts:
I found that Lipinski's rule of five states that Log P (octanol-water partition coefficient, lipophilicity measure) usually should not exceed 5.
Many papers about drug discovery machine learning models tell about maximization of "penalized logP", but the paper they refer in the end does not contain any information on it. Let me show that.
Let's check 1, here we read about penalized log P:

The second task is to produce novel molecules with desired properties.
Following (Kusner et al., 2017),  our target chemical property y(·)is
octanol-water partition coefficients (logP) penalized by the
synthetic accessibility (SA)score and number of long cycles

y(m) = logP(m)−SA(m)−cycle(m) where cycle(m)counts the number of rings that have more than six atoms.

Then we go into Kusner et al., 2017:

For the second optimization problem, we follow (Gómez-Bombarelli et
al., 2016b) and optimize the drug properties of molecules.  Our goal is
to maximize the water-octanol partition  coefficient  (logP),  an
important  metric  in  drug design that characterizes the drug-likeness
of a molecule.As in Gómez-Bombarelli et al. (2016b) we consider a
penalized  logP  score  that  takes  into  account  other  molecular
properties  such  as  ring  size  and  synthetic  accessibility
(Ertl  &  Schuffenhauer,  2009).

Here is Gómez-Bombarelli, 2016 and it seems to contain nothing on the topic (I can be mistaken, please point me then), except

The objective we chose to optimize was 5×QED−SAS, where QED is the
Quantitative Estimation of Drug-likeness (QED),37 and SAS is the Synthetic
Accessibility score.36Thisobjective represents a rough estimate of
finding the most drug-like molecule that is also easy to synthesize.

Other examples of the papers also leading to the same papers are 2, 3, etc.
What does penalized logP mean for drug-likeliness and why it should be maximized?


texts:
Why is the threshold between human embryo and human fetus defined as 8 weeks after fertilization? What's happening on the 8th week?

Note: definition of embryo based on Wikipedia's current definition.


texts: What are the metabolic concerns associated with hard water?

texts:
If humans can maintain a consistent blood pH, then what problems does alkalized water cause us?

Why is it recommended that we filter and boil hard water? Is the issue that hard water can affect the pH of our blood?


texts: It includes the basal plate, the pool of blood between the chorionic plate and the basal plate and the chorionic plate, what else?


texts: Why heart beats increase when we are in a state of tension even though it is a disadvantage?

texts:
Suppose a poisonous snake bites you; this will likely cause hypertension, and it will result in your heart rate increasing dramatically.

Because of the high rate of heart beats, your body will make the snake poison circulate throughout the whole body even faster. This will likely bring about death even faster. (definitely 100% disadvantage)

Why do heart beats increase when we are in a state of tension even though it is to our disadvantage?


texts:
As the original question went from hold to closed, I thought I would write up a more appropriate question.

How should one go about getting bacterial samples to look at under a microscope at home?  How do professionals do it?  What if I want to look at cool pathogenic species like Salmonella bongori, Escherichia coli, or Bacillus anthracis?


texts: Does our brain contain an innate function about closing only one eye?

texts:
I wasn't sure where to post this, but biology seemed fitting for me. Sorry if I'm wrong.

I was wondering why, when we close both our eyes and look at light, it is clear we can see the light even though our eyes are closed. We can identify where the light is too.

However, when you look at the light with only one eye closed, suddenly you cannot perceive this anymore and you can only focus on the open eye's vision. It's like our brain is ignoring the closed eye's vision somehow. What is triggering this "ignore vision"? Is it the closing of the eye?

I found this intriguing and wondered how this works and/or if there is any research about it.


texts:
Well, a friend of mine sent me this picture of an creepy insect. I'm wondering if the picture is photoshoped or if it is real. It is said the insect lives in Indonesia, but I'm not sure.

Can anyone identify this? Thanks.


texts: Why would a bumblebee regularly hover over a arborvitae hedge?

texts:
I have observed bumblebees hover over an a abrborvitae (Thuja occidentalis) hedge. A bumblebee will hover in a in one spot over the hedge for about 5-7 seconds, zip to another spot, hover for about 5-7 seconds, then another spot, then another. The bees will never land on the hedge. At any one time during anyone day, there will be only one bee hovering over the hedge. This behavior will go on like this all day.

Why do the bees do this?


texts: When happens when pollen grains land on the a part other than the stigma of a flower of the same species? Would the pollen be transported to the stigma or would it just sit where it landed and nothing would happen?


texts: How are dental cavities different from body injuries?

texts: I always had this question why dental cavities cause pain. I stumbled on this question on the reasons why dental cavities are painful. I have a followup question on how dental cavities are different from bodily injuries. I was under the impression that pain causes inflammation which in turn triggers something like mitosis that causes healing. Why does the same not happen with the dental cavities? Why are they not treated like the bodily injuries?


texts: Why is 5S-rRNA is different from other rRNAs in place of transcription and usage of RNA polymerase?

texts: While transcription of rRNAs happens in nucleolus mediated by RNA Polymerase-I, we see that 5S-rRNA is transcribed elsewhere by RNA Polymerase-III. What is the cause and why?


texts: Do Alzheimer's patients have spaces in their brain with low interstitial space?

texts:
Lulu Xie et al write in their paper Sleep Drives Metabolite Clearance from the Adult Brain:

  Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with interstitial fluid. In turn, convective fluxes of interstitial fluid increased the rate of β-amyloid clearance during sleep.

Given that Alzheimer's patients have more β-amyloid in their brains, do they also have less interstitial space?


texts: Is there a hormone or group of hormones that regulates when we feel sleepy late at night, or in the morning?  Or is sleepiness caused by some other non-hormonal mechanism?  (e.g. pure psychological, or neuronal.)


texts: When should you use a stringent plasmid?

texts: I was wondering if anyone had good examples of when you would want to use a stringent plasmid vs. a relaxed plasmid in a research setting.


texts: Why is there a weevil on top of a beetle?

texts:
A click beetle was walking around and there is a weevil on top of it.

Any idea why? I would also like to know the exact species of these insects.

 !

Time: 18:50, place: Netherlands / Noord-Hollands / Overveen / the Amsterdamse waterleiding duinen / it's in the dunes near forest and grasslands near the dunes


texts: How does anger relate to blood pressure?

texts: Anger is an emotion generated by neural processes in the brain and is associated with elevated blood pressure. How can an emotion, which is totally related to brain, result in blood pressure changes?


texts: I found this stone in the arizona desert. Sort of far from humans on the side of a Butte


texts:
Majority of crustacean larvae have expanded carapace drawn out into processes as an adaptation for :

a. Protection from enemies

b. Planktonic habit

The answer given is b but I think it should be (a) as carapace functions as an exoskeleton.

Please help!


texts: How much cost would artificial pollination add to common products (fruits etc.)?

texts:
I've read about ecosystem services and their possible valuation - statements like "honeybee pollination service in the US is worth 1.6 billion dollars".

Is data available on how this would affect the cost a consumer pays for a given product? For example if the humans must do all pollination of fruits themselves, how would that affect the retail cost of these fruit?


texts: What are the (correct) terms for these flagella-arrangements?

texts:
I came across the following diagrams depicting two kinds of arrangement of flagella over cells.

Now according to my (very unreliable) school textbook, the arrangements are termed as:

A - Cephalotrichous (tuft of flagella on one end)
B - Lophotrichous (tufts of flagella on both ends)

Whereas another (equally unreliable) book states the exact opposite:

A - Lophotrichous (tuft of flagella on one end)
B - Cephalotrichous (tufts of flagella on both ends)

A spot of cursory Googling reflects this sort of confusion online (compare the images and their labels here) as well.

According to Wikipedia that arrangement A is lophotrichous, but it makes no reference to arrangement B though.

I tried to figure it out, going by the smattering of Greek I picked up as a Bio. student ( Cephalos = Something to do with the head ; Lophos = something to do with a peak/protuberance ), I arrived at:

  Hmm... so cephalotrichous probably means you find the tuft on one "end" (so arrangement A), and ipso facto lophotrichous is arrangement B.

But I guess, I ended up putting a little too much thought into it...

  Cephalotrichous is probably used to indicate you have a tuft on the "head" in addition to another tuft on the "tail" (so arrangement B), and ipso facto lophotrichous is arrangement A.

 At this stage I'm not sure what's more serious: my inability to find an authoritative answer to my question... or my tendency to overthink stuff

I'm in a fix.

Could someone clarify, citing (multiple, if possible) authoritative sources, on the distinction between a "cephalotrichous" and a "lophotrichous" arrangement?


texts: How does hibernation reduce risk of radiation-induced mutation?

texts:
A recent documentary (skip to 58:20) discusses the possibility that hibernation, if it could be induced in extrasolar astronauts, would reduce damage from cosmic radiation. The obvious reason this could happen is the shielding of hibernation chambers, but the documentary reviews evidence that even hibernation in the wild (e.g. bears) reduces radiation damage due to a slowed metabolism.

I would assume the connection is that reduced need for enzyme synthesis keeps DNA coiled up most of the time so its nucleotides are less exposed to radiation, but even if this is true it raises the question of how coiling shields radiation. (For example, is it less able to penetrate histones or the phosphorylated deoxyribose backbone?) Adding to my confusion, the documentary claims the mechanism is rooted in hydrogen sulphide, but doesn't explain either why this is more concentrated in the cells of hibernating animals nor how it reduces mutations.


texts: What really is color and how do we perceive it?

texts: How do our brains actually transform the information that the cones in our eyes  receive into the different colors that we can see and imagine?


texts:
They look like monkey grass, in the midst, a tall, skinny stem with bright orange flowers on top.
One of the plants, although it looks just like the others, has pink, purplish flowers instead of orange.

I would like to know what these are so I can start to take care of them properly.


texts: Does the Histogen Theory apply to plant roots as well as stems?

texts:
My school textbook briefly mentions a certain "Histogen Theory" (von Hanstein) of plant growth/development. However, I can't find any authoritative source on this matter online.

According to my book, as well as this site, the Histogen Theory is only used to model the development of the shoot (stem) apex.

But according to the definition on Merriam-Webster, the Histogen Theory is applicable to both the shoot and root systems.

Question:

Is the Histogen Theory applicable to only shoot apices (as some sources suggest), or does it instead, apply to both shoot and root apices?


texts: Advantages of gregarious vs solitary behaviour?

texts:
I'm trying to explain why birds (specifically wildfowl) are gregarious during the winter and solitary during the summer.

I think that in winter, birds are gregarious to reduce the risk of predation and to share foraging information. But gregariousness also brings with it competition, and because birds have offspring to feed in the summer, they trade-off increased predation/loss of information with reduced competition.

Does this sound correct?


texts: Does antibody-production play a significant role in viral infection-response?

texts:
My question targets the role of newly produced antibodies in prevention of later disease versus their role in the acute current infection.
Initially, my interpretation of the typical viral immune response was, that production of additional antibodies is crucial: Antibodies that are present at the time of infection, which are able to detect viral particles, will be recognized by immune-cells, some of which trigger activation of the immune-system through cytokines. The activated innate immune-system merely stalls time until production of these corresponding antibodies finally leads to high antibody-concentrations so that the viral infection can be overcome.
However, recently I read that "antibodies show up 10-20 days" after CoV-2 infection [1], I wonder whether viral infections, in general, need high antibody-concentrations to be overcome.
Additionally, from an invited presenter (Prof. Krammer), I know that people who had a CoV-2 infection, in some cases, don't develop sufficient titers to prevent later infections, and thus, people should generally be vaccinated, even if they were CoV-2 positive.
So, my question is: Is it possible that viral infections (sometimes) can be completely overcome before newly produced antibodies play an effective role in the immune-response? Is it a valid assumptions that this would mostly be seen in 'silent infections'?


texts: How quickly is antibiotic resistance lost?

texts:
I would imagine the bacterial genome is highly conserved and limited in its space, but maybe I am wrong.

If you were to take a strain of antibiotic resistant bacteria and kept them isolated, but fed well and so forth, how long would it take for them to lose their resistance? A year? A decade? 100 years? 1000 years? At some point it seems like that trait would disappear, but I have no feeling for how long. Please support your answer with a relevant citation.

EDIT:

My purpose is simple: I am thinking about a strategy for dealing with antibiotic resistance. If we were to ban them across the entire world (could be impossible) how long would we need to wait before they would be usable again. If it was a matter of years, then we could almost do a rotation of existing antibiotics (if we had enough) because I would rather not live in post-antiobitic world.


texts: Can dopamine antagonists be used as dopamine upregulation?

texts:
Can dopamine antagonists such as Thorazine that are used to treat schizophrenia and bipolar be used to upregulate dopamine in the long term in healthy (non schizophrenic or bipolar) users to get a similar effect as a stimulant high without inducing neurotoxicity? Due to tolerance buildup of the dopamine blocker, my assumption is that it should result in dopamine upregulation when dopamine antagonist use is stopped.

As an example, in extremely high doses of methamphetamine, meth induces temporary schizophrenia (skin picking, crank bugs, paranoia, hallucinations, etc), and extremely similar, if not exact, effects to bipolar, which are the only two neurological diseases resulted from dopamine over-production and release. Over time, tolerance to meth builds up and it stops being effective, unless it is stopped for a period of time resulting in reverse-tolerance. Can this same dopamine downregulation effect be used in dopamine antagonists as dopamine upregulation, creating the same euphoric feeling resulted from meth use or bipolar hypomania if the dopamine antagonist is taken for a period of time then stopped?


texts: I'm aware of the existence of circadian clocks, but I don't understand exactly how circadian clocks regulate other circadian mechanisms. For example, if an enzyme is found to have a circadian rythm, how is this rhythm produced? Is it because of one or more clock genes?


texts: Do we need to drink less water in humid weather than in dry weather?

texts:
From my understanding, humid weather means that the air has a lot of water in it. Therefore, someone who lives in this kind of weather would be hydrating himself just by breathing.

Does that mean that, to stay hydrated, one needs to drink less water in humid weather than in dry weather?

Of couse, I know that humid weathers are usually hotter, which accelerates dehydration. But in this case, let's assume the temperature is independent of the humidity of the air.


texts: Edman method to identify peptides with Phenylisothiocyanate (PTH)

texts:
We all know that in this method the PTH reacts with the first amino acid (aa) from the N-terminal to the peptide and separates from it giving PTH-aa so that we can know the amino acids sequence in the peptide.

The question is what prevents the PTH from reacting with the second amino acid after it separates with the first amino acid in the same time and phase? Because if it does we can't distinguish between the first and second amino acid residue in the sequence.


texts:
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process.
I used the word "fibrogenesis" as the outcome of acute inflammation (healing).
My colleges use the word "fibrosis".
The fibrogenesis seems to be used with the emphasises of the genetic part.

What is the difference between fibrogenesis and fibrosis?


texts: Can you help identify this bird in Louisville Kentucky?

texts: This bird shows up in my back yard every night.  It is calling and sometimes I hear a bird in the distance calling back.  I think its an owl but I haven't seen it yet.  Any ideas what it is?


texts: Found this outside on patio in northern Virginia, Ashburn area, September 2018. It's about 12 inches. Is it a water snake or rattlesnake?


texts: IgA-s in an immune system vaccined intramuscularly against Hepatisis A

texts:
As IgA are immunoglobulins associated with secretion and mucosis membranes, I am interested whether after intramuscular vaccination with Hepatitis A vaccine IgA antibodies will be produced by the immune system before an actual infection?

Also, would they be secreted into breast milk, intestine lumen etc. before the infection coming in a traditional (gestational) way?

Or does it take to have the antigen presented at the mucosis mambrane to start IgA production or secretion?


texts: Identification of Insect found on beach in Maharashtra

texts: Six legs, two antennas, Neon green colour pattern with black. Had no wings.


texts: Proteins that give color (without fluorescence)

texts:
Is there proteins that have strong color, that could be seen without the need of UV and with naked eyes (with white light) - in mammalian cells?

Searching for reporter, something like GFP, but that we could see it without UV (not fluorescence).

Like chromoprotein - but it is problematic in mammalian cells because most chromoproteins need a prosthetic group.