Instruct: Given a question, retrieve passages that answer the question.
Query: Who first identified the cell?
In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction. With continual improvements made to microscopes over time, magnification technology advanced enough to discover cells in the 17th century. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, also known as cell biology. Over a century later, many debates about cells began amongst scientists. Most of these debates involved the nature of cellular regeneration, and the idea of cells as a fundamental unit of life. Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory. It was an important step in the movement away from spontaneous generation.
Group C
The name "autophagy" was coined by Belgian biochemist Christian de Duve in 1963 based on his discovery of the functions of lysosome. The identification of autophagy-related genes in yeast in the 1990s let researchers figure out the mechanisms of autophagy, which eventually led to the award of the 2016 Nobel Prize in Physiology or Medicine to Japanese researcher Yoshinori Ohsumi.
Later artificial cells have ranged from hundred-micrometer to nanometer dimensions and can carry microorganisms, vaccines, genes, drugs, hormones and peptides. The first clinical use of artificial cells was in hemoperfusion by the encapsulation of activated charcoal.
Christian de Duve coined the term autophagy in 1963 whereas Ohsumi began his work in 1988. Prior to that time, less than 20 papers per year were published on this subject. During the 1990s, Ohsumi's group described the morphology of autophagy in yeast, and performed mutational screening on yeast cells that identified essential genes for cells to be capable of autophagy.
In August 1961, at the International Congress of Biochemistry in Moscow, Nirenberg presented his paper. The experimentation with synthetic RNA in a cell-free system was a key technical innovation. In 1961, when they announced their methods for decoding the relationship of mRNA to amino acids, there was still a lot of experimentation required before the entire code was deciphered. The scientists had to determine which bases made up each codon, then determine the sequence of bases in the codons. This proved to be a tremendous amount of work.
In 1895 (seventy-five years later), Émile van Ermengem, professor of bacteriology and a student of Robert Koch, correctly described "Clostridium botulinum" as the bacterial source of the toxin. Thirty-four attendees at a funeral were poisoned by eating partially salted ham, an extract of which was found to cause botulism-like paralysis in laboratory animals. Van Ermengem isolated and grew the bacterium, and described its toxin, which was later purified by P Tessmer Snipe and Hermann Sommer.
Michigan State University, Kellogg Biological Station: Eminent Ecologist (1992)
In 1880, while working in the military hospital in Constantine, Charles Louis Alphonse Laveran discovered that the cause of malaria is a protozoan. He observed the parasites in a blood smear taken from a soldier who had just died of malaria. For this, he received the 1907 Nobel Prize for Physiology or Medicine. This was the first time that protozoa were shown to be a cause of disease. His work helped inspire researchers and veterinarians today to try to find a cure for malaria in animals.
Secretin was the first hormone to be identified. In 1902, William Bayliss and Ernest Starling were studying how the nervous system controls the process of digestion. It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum. They discovered (by cutting all the nerves to the pancreas in their experimental animals) that this process was not, in fact, governed by the nervous system. They determined that a substance secreted by the intestinal lining stimulates the pancreas after being transported via the bloodstream. They named this intestinal secretion "secretin". Secretin was the first such "chemical messenger" identified. This type of substance is now called a hormone, a term coined by Bayliss in 1905.
The first model known as the "syntrophic model" proposes that a symbiotic relationship between the archaea and bacteria created the nucleus-containing eukaryotic cell. (Organisms of the Archaea and Bacteria domain have no cell nucleus.) It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. The archaeal origin of the nucleus is supported by observations that archaea and eukarya have similar genes for certain proteins, including histones. Observations that myxobacteria are motile, can form multicellular complexes, and possess kinases and G proteins similar to eukarya, support a bacterial origin for the eukaryotic cell.
Major Alfred Whitmore (1876–1946) was an English pathologist who, together with C.S. Krishnaswami, identified "Burkholderia pseudomallei", the causative agent of melioidosis (also known as "Whitmore's disease") in opium addicts in Rangoon in 1911. He differentiated it from "Burkholderia mallei", the causative agent of glanders, by clinical and microbiological features.
A German physician, Johann Friedrich Meckel, must have been the first to see "P. falciparum" but not knowing what it was. In 1847 he reported the presence of black pigment granules from the blood and spleen of a patient who died of malaria. The French Army physician Charles Louis Alphonse Laveran, while working at Bône Hospital (now Annaba in Algeria), correctly identified the parasite as a causative pathogen of malaria in 1880. He presented his discovery before the French Academy of Medicine in Paris, and published it in "The Lancet", in 1881. He gave the scientific name "Oscillaria malariae". But his discovery was received with skepticism mainly because by that time leading physicians such as Theodor Albrecht Edwin Klebs and Corrado Tommasi-Crudeli claimed that they had discovered a bacterium (which they called "Bacillus malariae") as the pathogen of malaria. Laveran's discovery was widely accepted only after five years when Camillo Golgi confirmed the parasite using better microscope and staining technique. Laveran was awarded the Nobel Prize in Physiology or Medicine in 1907 for his work. In 1900, the Italian zoologist Giovanni Battista Grassi categorized "Plasmodium" species based on the timing of fever in the patient; malignant tertian malaria was caused by "Laverania malariae" (now "P. falciparum"), benign tertian malaria by "Haemamoeba vivax" (now "P. vivax"), and quartan malaria by "Haemamoeba malariae" (now "P. malariae").
In 1820, Justinus Kerner, a small-town German medical officer and romantic poet, gave the first complete description of clinical botulism based on extensive clinical observations of so-called “sausage poisoning”. Following experiments on animals and on himself, he concluded that the toxin acts by interrupting signal transmission in the somatic and autonomic motor systems, without affecting sensory signals or mental functions. He observed that the toxin develops under anaerobic conditions, and can be lethal in minute doses. His prescience in suggesting that the toxin might be used therapeutically earned him recognition as the pioneer of modern botulinum toxin therapy.
The discovery of insulin at the University of Toronto in 1921 is considered among the most significant events in the history of medicine. The stem cell was discovered at the university in 1963, forming the basis for bone marrow transplantation and all subsequent research on adult and embryonic stem cells. This was the first of many findings at Toronto relating to stem cells, including the identification of pancreatic and retinal stem cells. The cancer stem cell was first identified in 1997 by Toronto researchers, who have since found stem cell associations in leukemia, brain tumors and colorectal cancer. Medical inventions developed at Toronto include the glycaemic index, the infant cereal Pablum, the use of protective hypothermia in open heart surgery and the first artificial cardiac pacemaker. The first successful single-lung transplant was performed at Toronto in 1981, followed by the first nerve transplant in 1988, and the first double-lung transplant in 1989. Researchers identified the maturation promoting factor that regulates cell division, and discovered the T-cell receptor, which triggers responses of the immune system. The university is credited with isolating the genes that cause Fanconi anemia, cystic fibrosis and early-onset Alzheimer's disease, among numerous other diseases. Between 1914 and 1972, the university operated the Connaught Medical Research Laboratories, now part of the pharmaceutical corporation Sanofi-Aventis. Among the research conducted at the laboratory was the development of gel electrophoresis.
In 1961, Jacques Monod, Jean-Pierre Changeux and François Jacob discovered the lac operon in the bacterium "Escherichia coli". It was a cluster of genes, arranged in a feedback control loop so that its products would only be made when "switched on" by an environmental stimulus. One of these products was an enzyme that splits a sugar, lactose; and lactose itself was the stimulus that switched the genes on. This was a revelation, as it showed for the first time that genes, even in an organism as small as a bacterium, were subject to fine-grained control. The implication was that many other genes were also elaborately regulated.
A French Army physician Charles Louis Alphonse Laveran discovered that malaria was caused by microscopic parasite (now called "Plasmodium falciparum") in 1880. But scientists were sceptical until Golgi intervened. It was Golgi who helped him prove that malarial parasite was a microscopic protozoan. From 1885, Golgi studied the malarial parasite and its transmission. He established two types of malaria, tertian and quartan fevers caused by "Plasmodium vivax" and "Plasmodium malariae" respectively. In 1886, he discovered that malarial fever (paroxysm) was produced by the asexual stage in the human blood (called erythocytic cycle, or Golgi cycle). In 1889-1890, Golgi and Ettore Marchiafava described the differences between benign tertian malaria and malignant tertian malaria (the latter caused by "P. falciparum"). By 1898, along with Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli and Marchiafava, he confirmed that malaria was transmitted by "Anopheline" mosquito.
William Grove produced the first fuel cell in 1839. He based his experiment on the fact that sending an electric current through water splits the water into its component parts of hydrogen and oxygen. So, Grove tried reversing the reaction—combining hydrogen and oxygen to produce electricity and water. Eventually the term "fuel cell" was coined in 1889 by Ludwig Mond and Charles Langer, who attempted to build the first practical device using air and industrial coal gas. He also introduced a powerful battery at the annual meeting of the British Association for the Advancement of Science in 1839. Grove's first cell consisted of zinc in diluted sulfuric acid and platinum in concentrated nitric acid, separated by a porous pot. The cell was able to generate about 12 amperes of current at about 1.8 volts. This cell had nearly double the voltage of the first Daniell cell. Grove's nitric acid cell was the favourite battery of the early American telegraph (1840–1860), because it offered strong current output.
Dmitri Mendeleev published a periodic table of the chemical elements in 1869 based on properties that appeared with some regularity as he laid out the elements from lightest to heaviest. When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that as-then-unknown elements existed with properties appropriate to fill those gaps. He named them eka-boron, eka-aluminium and eka-silicon with atomic masses 44, 68 and 72 respectively.
The history of biochemistry can be said to have started with the ancient Greeks who were interested in the composition and processes of life, although biochemistry as a specific scientific discipline has its beginning around the early 19th century. Some argued that the beginning of biochemistry may have been the discovery of the first enzyme, diastase (today called amylase), in 1833 by Anselme Payen, while others considered Eduard Buchner's first demonstration of a complex biochemical process alcoholic fermentation in cell-free extracts to be the birth of biochemistry. Some might also point to the influential work of Justus von Liebig from 1842, "Animal chemistry, or, Organic chemistry in its applications to physiology and pathology", which presented a chemical theory of metabolism, or even earlier to the 18th century studies on fermentation and respiration by Antoine Lavoisier.
The discovery of a role for the pancreas in diabetes is generally ascribed to Joseph von Mering and Oskar Minkowski, who in 1889 found that dogs whose pancreas was removed developed all the signs and symptoms of diabetes and died shortly afterwards. In 1910, Sir Edward Albert Sharpey-Schafer suggested that people with diabetes were deficient in a single chemical that was normally produced by the pancreas—he proposed calling this substance insulin, from the Latin "insula", meaning island, in reference to the insulin-producing islets of Langerhans in the pancreas. The endocrine role of the pancreas in metabolism, and indeed the existence of insulin, was further clarified in 1921, when Sir Frederick Grant Banting and Charles Herbert Best repeated the work of Von Mering and Minkowski, and went further to demonstrate they could reverse induced diabetes in dogs by giving them an extract from the pancreatic islets of Langerhans of healthy dogs. The islets of Langerhans was discovered in 1869 by an anatomist named Paul Langerhans. He identified the keys cells in the pancreas which produce the main substance that controls glucose levels in the body.
Dopaminergic cell groups are collections of neurons in the central nervous system that synthesize the neurotransmitter dopamine. In the 1960s, dopamine neurons were first identified and named by Annica Dahlström and , who used histochemical fluorescence. The subsequent discovery of genes encoding enzymes that synthesize dopamine, and transporters that incorporate dopamine into synaptic vesicles or reclaim it after synaptic release, enabled scientists to identify dopaminergic neurons by labeling gene or protein expression that is specific to these neurons.
Alexander Friedenstein and his colleagues first identified osteoprogenitor cells in multiple mammalian tissues, before any genetic or morphological criteria were put in place for bone marrow or connective tissues. Osteoprogenitor cells can be identified by their associations with existing bone or cartilage structures, or their placement in the embryo, as the sites for osteogenesis and chondrogenesis are now known.
Anton van Leeuwenhoek is another scientist who saw these cells soon after Hooke did. He made use of a microscope containing improved lenses that could magnify objects almost 300-fold, or 270x. Under these microscopes, Leeuwenhoek found motile objects. In a letter to The Royal Society on October 9, 1676, he states that motility is a quality of life therefore these were living organisms. Over time, he wrote many more papers in which described many specific forms of microorganisms. Leeuwenhoek named these “animalcules,” which included protozoa and other unicellular organisms, like bacteria. Though he did not have much formal education, he was able to identify the first accurate description of red blood cells and discovered bacteria after gaining interest in the sense of taste that resulted in Leeuwenhoek to observe the tongue of an ox, then leading him to study "pepper water" in 1676. He also found for the first time the sperm cells of animals and humans. Once discovering these types of cells, Leeuwenhoek saw that the fertilization process requires the sperm cell to enter the egg cell. This put an end to the previous theory of spontaneous generation. After reading letters by Leeuwenhoek, Hooke was the first to confirm his observations that were thought to be unlikely by other contemporaries.
In neuroscience, Golgi cells are inhibitory interneurons found within the granular layer of the cerebellum. They were first identified as inhibitory by Eccles "et al." in 1964.
It was also the first example of an inhibitory feed back network, where the inhibitory interneuron was identified anatomically.
These cells synapse onto the dendrite of granule cells and unipolar brush cells. They receive excitatory input from mossy fibres, also synapsing on granule cells, and parallel fibers, which are long granule cell axons. Thereby this circuitry allows for feed-forward and feed-back inhibition of granule cells.