{'fraction_non_alphanumeric': 0.021636240703177823, 'fraction_numerical': 0.011494252873563218, 'mean_word_length': 5.406926406926407, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Reproductive and Overwintering Adaptations in Northern Pike (Esox lucius L.): Balancing Essential Fatty Acid Requirements with Dietary Supply

In northern pike, ovarian recrudescence and membrane lipid restructuring occur during winter and may thereby create physiological requirements for essential fatty acids (EFAs) that surpass dietary EFA intake. Seasonal changes in the fatty acid composition of pike ovary and whole-body lipids and mass balance comparisons were used to identify mechanisms that during winter help balance physiological requirements for EFAs with the dietary supply. Mature ovaries of pike exhibited a polar lipid:neutral lipid ratio (70:30; based on the weight of fatty acids) much greater than that of somatic tissues (30:70), yet the fatty acid compositions of ovarian and somatic total lipids were quite similar. This similarity resulted from an adaptive reduction in the percentage of n-3 EFAs in ovarian neutral and polar lipids to levels lower than those typical of somatic lipids. Adaptive features of ovarian fatty acid composition, combined with significant reductions in the n-3 EFA content of somatic neutral lipids during winter, reduced the n-3 EFA requirements associated with ovarian recrudescence by 55%. The fatty acid compositions of ovarian and somatic total lipids differed in one important aspect: ovarian total lipids were considerably enriched in 22:6n3. This may be an adaptation to the insectivorous feeding habits of larval pike.