Genomic signatures of recombination in a natural population of the bdelloid rotifer Adineta vaga.

Sexual reproduction is almost ubiquitous among extant eukaryotes. As most asexual lineages are short-lived, abandoning sex is commonly regarded as an evolutionary dead end. Still, putative anciently asexual lineages challenge this view.

[Fish ovarian fluid contains protease inhibitors].

Studies of the conditions under which fish egg is activated spontaneously without the sperm showed that the egg retains the ability for fertilization in the ovarian (coelomic) fluid, which surrounds it in the gonad cavity after ovulation. Earlier, we showed that, in artificial media, the spontaneous activation is suppressed by protease inhibitors. In this study, we investigated the presence of natural protease inhibitors in the ovarian fluid and showed that the ovarian fluid of zebrafish and loach contains protease inhibitors, in particular, type I serpin a, a protein inhibitor of trypsin proteases.

[Spontaneous activation of fish eggs is abolished by protease inhibitors].

During spawning, eggs of most fish species entering the aquatic environment remain fertilizable for a relatively short period of time. This is due to the "spontaneous egg activation" giving rise to the fertilization membrane, which prevents the penetration of excessive and foreign sperm into the egg during normal fertilization. This work demonstrates that the fertilization membrane formation and the loss of fertilizability in aqueous solutions of different composition are inhibited by protease inhibitors, in particular, leupeptin and aprotinin.

[A study of proteins of annexin group in early fish development. IV. Identification of calcium-binding proteins in zebrafish egg by mass spectrometry].

Calcium-binding proteins were isolated from zebrafish (Brachidanio rerio) eggs by the method of precipitation with acidic phospholipids in the presence of calcium ions. The revealed proteins separated by SDS-PAGE were identified by mass spectrometric tryptic peptide fingerprinting. The proteins included annexins A2a, A1a, A13.

[A study of annexin family protein in early development of fish. II. Analysis of complete amino acid sequence].

We studied mRNA structure of 31 kDa annexin of zebra fish Brachydanio rerio using previously obtained 3'-terminal incomplete cDNA. The size of this protein mRNA was determined by Northern hybridization. PCR screening of cDNA library of zebra fish gastrula allowed us to obtain cDNA of the 5'-terminal regions of the mRNA.

[The temperature dependence of selection efficiency and the expression of the genes controlling the rate of embryonic development in Drosophila melanogaster].

We have already shown that selection of heterogeneous D. melanogaster populations for the rate of embryogenesis at 32 degrees C may produce populations, in which 50% of the larvae are hatched 20-40 min earlier, i.e.

[Properties of inbred Drosophila melanogaster lines obtained from a population selected for an increased rate of embryonic development].

Two heterogeneous Drosophila melanogaster populations were subjected to selection for an increased rate of embryonic development by picking out the first 10% of hatching larvae. After repeating this procedure in 15 generations, "fast" populations were obtained, in which the duration of embryonic development at high temperature (31-32 degrees C) was 30-40 min less than in nonselected control populations. The results of preliminary experiments on substituting the second and third chromosomes in the selected and control populations provide evidence that selected genes responsible for accelerated development are located on the second chromosome.

Phalloidin inhibits cortical granule exocytosis and ooplasmic segregation in loach eggs.

Injections of phalloidin under the surface of loach eggs, followed by activation of the eggs in tap water, result in local inhibition of cortical granule (CG) exocytosis. Light and electron microscopy revealed that in the region where exocytosis is inhibited the thickness of the microfilamentous cortex (MC) separating CGs from the plasma membrane (PM) is increased significantly, and many CGs are detached and have moved away from the MC. Injections of phalloidin also inhibit ooplasmic segregation in fertilized eggs.