Denis Efremov

Activity of metabolic enzymes and muscle-specific gene expression in parr and smolts Atlantic salmon Salmo salar L. of different age groups

This study was conducted to characterize the energy metabolism level and the features of muscle growth regulation during the development of Atlantic salmon (Salmo salar) inhabiting the Indera River (Kola Peninsula, Russia). The activities of aerobic and anaerobic enzymes (cytochrome c oxidase and lactate dehydrogenase) and carbohydrate metabolism enzymes (glucose-6-phosphate dehydrogenase, glycerol-3-phosphate dehydrogenase, and aldolase) were measured in muscle and liver tissue. Gene expression levels of myosin heavy chain (MyHC), myostatin (MSTN-1a), and myogenic regulatory factors (MRFs—MyoD1a, MyoD1b, MyoD1c, Myf5, myogenin) were measured in the white muscles of salmon parr of ages 0+, 1+, 2+, and 3+ and smolts of ages 2+ and 3+. Multidirectional changes in the activity of enzymes involved in aerobic and anaerobic energy metabolism with age were shown in the white muscles of the parr. The cytochrome c oxidase activity was higher in muscles of underyearlings (0+) and yearlings (1+) and decreased in 2+ and 3+ age groups. The activity of lactate dehydrogenase, in contrast, increased with age. The patterns of changes in expression levels of MyoD1a, MyoD1b, myogenin, MyHC, and MSTN-1a at different ages of the parr were similar. Particularly, the expression of these genes peaked in the yearling parr (1+) and then decreased in elder groups. The differences were revealed in parameters studied between the parr and smolts. The level of aerobic and anaerobic metabolism enzyme activities was higher in the white muscles of smolts than in parr. The activity of carbohydrate metabolism enzymes was decreased in the smolts’ livers. The expression levels of MyHC, MyoD1a, MyoD1b, and myogenin were lower in smolts at age 2+ compared to parr. These findings expand our knowledge of age-related and stage-related features of energy metabolism and muscle development regulation in young Atlantic salmon in their natural habitat. The results might be used for monitoring of the salmon population during restoration and rearing.

Age-Specific Lipid and Fatty Acid Profiles of Atlantic Salmon Juveniles in the Varzuga River

The age-specific lipid and fatty acid profiles of juvenile Atlantic salmon at different ages (0+, 1+, and 2+ years) after hatching from nests located in the mainstream of a large Arctic River, the Varzuga River, and resettling to the favorable Sobachji shoal in autumn before overwinter are herein presented. The contemporary methods of the lipid analysis were used: thin layer chromatography and gas chromatography. The results show that the stability of the regulation of important functions in developing organisms is maintained through structural alterations in lipids. These alterations can be considered as a sequence of the modifications and changes in the ratios of certain lipid classes and fatty acids constituents. In general, changes in the lipids and fatty acids (FAs) maintained the physiological limits and controls through the adaptive systems of the organism. The mechanisms of juvenile fish biochemical adaptation to the environmental conditions in the studied biotope include the modification of the energy metabolism and anabolism, and here belongs to the energy characteristics of metabolic processes.

The ecology of the freshwater form of the Atlantic salmon Salmo salar L., the brown trout Salmo trutta L., and the freshwater pearl mussel Margaritifera margaritifera L. in Syuskyuyanyoki River (Basin of Lake Ladoga)

The locations and the area of the spawning–growing grounds have been assessed in the Syuskyuyanyoki River (the basin of Lake Ladoga), as has the population density of the juveniles of the freshwater form of the Atlantic salmon and the brown trout. The Atlantic salmon spawns at present on the rapids downstream of the hydroelectric power plant because of the insurmountable dam; the population density of this species has decreased dramatically. Only the landlocked form of the brown trout was found; the anadromous form was not. The brown trout has resettled along the major part of the river. We suggest that there are two subpopulations of the freshwater pearl mussel that differ with regard to the host for their larvae. The intensity of invasion of the juveniles of salmonids by the larvae of the freshwater pearl mussel and the survivability of glochidia did not depend on the host species. The growth rate of the mollusks and the age–size structure of the freshwater pearl mussel population have been assessed.

ON THE PROBLEM OF REPRODUCTIVE PRODUCTS HETEROGENEITY IN SALMONID FISH: PINK SALMON (ONCORHYNCHUS GORBUSCHA) EGGS CASE-STUDY

Исследование, проведенное на неоплодотворенной икре горбуши ( Oncorhynchus gorbuscha , сем. Salmonidae), было посвящено поиску причин отмеченного ранее феномена дифференциации эмбрионов и ранних личинок лососевых рыб по уровню метаболизма, двигательной активности и особенностям взаимодействия со средой обитания. Для выяснения возможных материнских эффектов было проведено сравнение размерных показателей и уровней активности протеолитических ферментов – лизосомальных катепсинов В и D и кальцийзависимых протеиназ (кальпаинов) – в яйцеклетках разной локализации: из передней, средней и задней третей яичников нерестящихся самок O . gorbuscha . Ранее проведенная характеризация протеолитического аппарата рыб показала исключительную важность указанных ферментов в регуляции роста и метаболических процессов в неоплодотворенной и оплодотворенной икре рыб. В нашем эксперименте не была выявлена достоверная индивидуальная вариабельность икринок из разных частей яичника как по массе, так и по уровню активности внутриклеточных протеиназ. Полученные результаты свидетельствуют о том, что причину физиологических и морфологических различий молоди лососевых, проявляющихся на эмбриональном и раннем постэмбриональном этапах ее развития, следует искать, по-видимому, в генетической гетерогенности оплодотворенного материала или его взаимодействиях со средой, но не в различии темпов роста и созревания яйцеклеток в яичниках рыб.