Dynamics of fatty acid composition of total lipids during embryonic development of Atlantic salmon Salmo salar L

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.     

HB mobile element in the Drosophila melanogaster genome: structural and functional analyses

The structure was analyzed for 60 annotated copies of the mobile genetic element (MGE) HB from the Drosophila melanogaster genome. The genomic distribution of HB copies was studied, and preferential insertion sites (hot spots) were identified, which presumably amount to several kilobases. Structural analysis of the open reading frame (ORF) and terminal repeats of HB was performed. All 26 HB copies retaining the ORF sequence have a stop codon in the same position. Consequently, the HB ORF proved indeed to code for an enzyme of 148 amino acid residues, relatively small for Tc1-family transposases. The ORF consensus sequence was established. HB{}1185 was identified as the only HB copy potentially coding for a functional protein. All 37 repeat-containing HB copies were analyzed. Of these, only four had functional terminal sequences, lacking, however, a functional transposase gene. A new 7762-bp copy of MGE roo was found in the D. melanogaster genome; the copy was earlier unavailable from databases and represents an insert in the HB{}1605 sequence.     

Evolution of errantiviruses of Drosophila melanogaster. Strategy 2: from retroviruses to retrotransposons

Drosophila melanogaster retrotransposons of the gypsy group are considered to be potential errantiviruses. Their infectivity is caused by the functional activity of the third open reading frame (ORF3) encoding the Env protein, which was probably captured from baculoviruses. Mobile genetic elements (MGEs) of the gypsy group can be conventionally divided into three subgroups: with three ORFs, with a defective ORF3, and without the ORF3. To establish the patterns of evolution of gypsy retrotransposons in D. melanogaster, the members of the three subgroups were examined. Structural analysis of retrotransposons opus and rover, which carry a defective ORF3, as well as retrotransposons Burdock, McClintock, qbert, and HMS-Beagle, which lack the ORF3, suggests that the evolution of these MGEs followed the pattern of loosing the ORF3. At the same time, an MGE of the same subgroup, Transpac, may be an ancestral form, which had acquired the env gene and gave rise to the first errantiviruses. The capture of the ORF3 by retrotransposons provided their conversion to a fundamentally new state. However, the ORF3 in the genome is not subjected to strong selective pressure, because it is not essential for intragenomic transpositions. Because of this, the process of its gradual loss seems quite natural.     

Dynamics of Lipid and Fatty Acid Content at Early Ontogenesis Stages in Pink Salmon Oncorhynchus gorbuscha (Walbaum, 1792) in a Natural Environment (Indera River,Kola Peninsula)

Russian Journal of Developmental Biology - A comparative study of lipid and fatty acid status at the early stages of pink salmon’s ontogenesis has been carried out in prespawn eggs, at the...     

Dynamics of lipid content during early development of freshwater salmon <Emphasis Type="Italic">Salmo salar</Emphasis> L.

Dynamics of lipid and phospholipid content was studied during early development of freshwater salmon Salmo salar L. from blastodisc formation (3 h) to hatching (108 days) as well as in eggs before fertilization. High and stable content of total lipids including structural phospholipids as well as relatively high content of triglycerides and its slight increase at the time of hatching have been demonstrated, which can indicate their utilization as the main energy source after hatching under conditions of deficient food and low fry activity for some time. Accumulation of a certain level of lipids in eggs before spawning is required for embryonic development and high survival after hatching. The significance of increasing and decreasing levels of structural lipids modulating membrane enzyme activities in metabolic changes before hatching is discussed.     

Genetic heterogeneity of Borrelia afzelii in the natural focus of the Middle Urals

As shown by sequencing the spacer rrf (5S)--rrl (23S) in 72 isolates of B. afzelii (one of the causative agents of Ixodes tick borne Borrelia infections) and the chromosomal gene coding protein P66 in 22 isolates, that in the natural focus located in the Middle Urals two different genetic subgroups (VS461 and NT28) of this genospecies simultaneously circulate. These subgroups are represented by 5 gene variants (rrf) 5S--(rrl) 23S and 5 allelic variants in gene p66. The latter, similarly to spacer gene variants, are not linked with a definite host and occur in different rrf--rrl variants of the infective agent. At the same time the definite species of vectors and carriers may be the host of several different B. afzelii variants, both in the spacer and in the gene coding protein P66, which maintains the genetic heterogeneity of B. afzelii population in the natural focus.