Adipose tissue is a lipid storage organ characterized by the pronounced accumulation of adipocytes. Although adipose tissues are found in various parts of the vertebrate body, it is unclear whether these tissues have a common ancestral origin or have evolved in several phylogenetic lineages by independent adipocyte accumulation events. To gain insight into the evolutionary history of vertebrate adipose tissues, we determined the distribution of adipocytes by oil red O staining in skeletal muscle of 10 teleost species spanning eight orders: Tetraodontiformes, Pleuronectiformes, Spariformes, Salmoniformes, Clupeiformes, Beloniformes, Osmeriformes, and Cypriniformes. Accumulation of adipocytes in the myoseptum was observed in many species, including red seabream, rainbow trout, Pacific herring, Pacific saury, zebrafish and giant danio. We also found some order-, species-, and swimming mode-specific distribution patterns of adipocytes: 1) almost complete absence of intramuscular adipocytes in the order Tetraodontiformes (torafugu and spotted green pufferfish), 2) clear adipocyte accumulation in the inclinator muscles of fin in Japanese flounder, 3) a large intramuscular adipose tissue at the root of the dorsal fin in ayu, and 4) thick lipid layers consisting of subcutaneous adipose tissue and red muscle lipids in pelagic migratory fish (Pacific herring and Pacific saury). Of note, Pacific herring and Pacific saury are phylogenetically distinct species sharing a similar niche and swimming mode, suggesting that their analogous adipocyte/lipid distribution patterns are the consequence of convergent evolution. The potentially heterogeneous origin of adipose tissues has significant implications for the interpretation of their functional diversity.
Since post-harvest improvement of food quality depends on the pre-harvest stage, controlling food quality at the pre-harvest stage is being recognized as an important aspect of food processing technology. n-3 Long-chain polyunsaturated fatty acids (n-3 LCPUFAs) are considered important factors in the suppression of cardiovascular disease and development of the infant brain and visual functions. Fish meat generally contains a larger amount of n-3 LCPUFAs than meat from terrestrial animals, but the amount of n-3 LCPUFAs in fish meat depends on their dietary fatty acid intake. In order to supply n-3 LCPUFAs to consumers, we developed a finishing-up method, through a 4-day lysine-deficient diet feeding for rainbow trout (Oncorhynchus mykiss) meat. This 4-day lysine deficiency did not affect fish body weight, while significantly increased the total lipid content in the muscle tissue. In addition, docosahexaenoic acid and total n-3 fatty acid contents increased significantly in the meat throughout the 4-day finishing treatment. We concluded that the finishing-up method using short-term lysine-deficient diet feeding enables us to enrich fish meat with n-3 fatty acids for human consumption.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.