Main results

LABORATORY OF EMBRYOLOGY: overview

Yushin, Vladimir Vladimirovich, Ph.D., Dr. Sci. (Biol.), Corresponding Member of the Russian Academy of Sciences (RAS), Head of the Laboratory of Embryology since 2003. He specializes in marine biology and zoology. His scientific interests include microscopic anatomy, comparative embryology, developmental biology of nematodes and other invertebrates.

Staff: 24, including 23 researchers, 5 of whom are Doctors of Sciences and 13 Ph.D.

The Laboratory of Embryology was established in 1973 by the Academician, Doctor of Sciences Vladimir Leonidovich Kasyanov (1940–2005), famous Russian scientist, specialist in reproductive strategy of marine invertebrates, at all levels of biological organization, from a cell to an organism and from a population to a species and a community.

The first stage of research of the laboratory in the 1970s was a comprehensive study of reproduction in common mollusk and echinoderm species of the Sea of Japan. The results of this study were summarized in a monograph, which has become a source of essential knowledge on the periods of reproduction of commercially important and dominant species. The next stage of research was a detailed description of the development, morphology, and metamorphosis in the larvae of marine mollusks and echinoderms.

Kasyanov’s monographs consider the problems of sex determination and differentiation, sexual dimorphism, gametogenesis, morphology of gametes, and early stages in the development of bivalves and echinoderms. These books give detailed descriptions of the morphology and adaptations of planktotrophic larvae to life in the pelagic zone, analyze the problems of fertility, energy of reproduction, describe larval settlement and recruitment, discuss the genetic aspects of reproductive strategies and adaptations of planktotrophic species to particular habitats, and give comparisons between planktotrophic and lecithotrophic strategies.

MAIN AREAS OF RESEARCH

The laboratory studies the reproductive and developmental patterns in marine organisms, including abundant and commercially important ones. The approaches used in the laboratory involve a wide range of methods, from histological, ultrastructural, and cytochemical to immunochemical methods and methods of molecular biology, from underwater observations to cell culture and computer simulation. The studied organisms include algae, sponges, coelenterates, flatworms, nemerteans, nematodes, polychaetes, mollusks, crustaceans, echinoderms, lophophorates, hemichordates, and chordates.

The areas of the laboratory research include the studies of stem cells, gametes, gametogenesis, and sex determinants; comparative and evolutionary embryology of marine organisms; larval development and metamorphosis in marine invertebrates; ecology of reproduction and development; non-linear processes and self-organization in the morphogenesis of organisms and their cell systems.

MAIN RESULTS

1. The mitochondrial origin of sex determinants has been morphologically proved. The results of the ultrastructural studies of spermatogenic cells in sea urchins indicate that the matrix and cristae of the inner mitochondrial membrane of these cells transform into specific granular-fibrillar material of the determinants of a sex cell line. These results agree with the data of molecular biology investigations showing that the sex determinants contain mitochondrial ribosomal 16S RNA.

2. Data on the structure and development of spermatozoa have been proposed for use in the analysis of the phylogeny and taxonomy of nematodes, and specific cytological principles of this analysis have been established. A new system of subclasses of the Class Nematoda based on the features of spermatozoon morphology and spermatogenesis has been proposed. The newly developed criteria are successfully applied to study the phylogeny of marine and parasitic nematodes.

3. Cell and tissue organization was studied in some multicellular organisms. The object of these studies include the neurons of the fish brain, cells aggregating in vitro, the gastrovascular system in medusas, the respiratory system in mayfly larvae, and the intern of rhizocephalan barnacles. The quasi-fractal patterns of the studied systems have been found out, and morphogenetic peculiarities, common for biological and non-biological systems, have been revealed. Patterns of transition from order to chaos were determined for branching epithelial channels, with disorder increasing at every successive step of dichotomic branching; simulation computer models were built of quasi-fractal cell self-organization; topological limitations were shown for biological morphogenesis.

4. Studies have shown that the capacity of stem cells to maintain their totipotency and to reproduce their cell line is universally controlled by germ cell determinants, i.e. by germ plasm granules formed with the participation of products of both nuclear and mitochondrial DNA.

5. Studies have shown that the in vitro culturing cells self-organize into ordered supracellular clusters. The topological patterns of these processes have been defined, including the relationships between the local and global aspects of biologic morphogenesis.

6. The Atlas and Keys for the Identification of the Larvae of Common Cirripedes (Cirripedia, Thoracica) of the Russian Coastal Seas was published.

7. The morphofunctional organization of stem cells supporting sexual and asexual reproduction in five invertebrate phyla (Porifera, Coelenterata, Plathelminthes, Rhizocephala, and Ascidia) has been found to be evolutionarily conservative. The self-renewing reserve of stem cells has been shown to be a basis for reproductive strategy comprising sexual and asexual reproduction.

8. The results of comparative studies of gametogenesis, gamete morphology, fertilization processes and early stages of zygote development in multicellular animals demonstrated that the general structure of spermatozoa is largely determined by the conditions of gamete contacts.

9. A large scale original and literature data analysis results in a concept of sperm cell evolution in multicellular animals, which suggests the presence of flagella as the primitive character. The study shows that in many taxa of multicellular animals the ancestral “flagellar” spermatogenesis evolves into the “specialized” spermatogenesis, in which sperm cells loose the characters of a primitive flagellar cell. The transformation of a primitive spermatozoon into a whole variety of specialized types of male gametes was analyzed through all phyla of invertebrates and vertebrates.

10. Spermatozoon polymorphism has been studied in nematodes (Nematoda). It has been shown that dimorphism in male gametes evolves independently in free-living and parasitic nematodes and has specific biological sense in each case. The dimorphism can provide a drastic increase of spermatozoon number or formation of clusters of dimorphic spermatozoa (spermatozeugmata), which enhance the efficacy of insemination. It may also serve as a means of intraspecific competition between males for the transfer of their genetic materials into oocytes (‘sperm competition’). In this case specialized ‘killer sperm’ destructing the spermatozoa of competing males form in the testes.

11. It has been shown that low phenol concentrations exert a complex damaging effect on the srtucture of gametes in sea urchins. The accessory cells reveal the characters of malfunction, and the reproductive potential in sea urchins generally decreases. Recommendation is given that the officially recommended safe level of phenol in the water should be even more lowered in all countries.

12. Using teleost fishes and echinoderms as an example, it has been shown that post-spawning gamete resorption in the testes may be accomplished both with the help of somatic accessory cells together with coelomocytes and by means of self-destruction of remaining gametes without the participation of somatic cells. In sea urchins a capability of phagocytes to selective resorption has been found.

13. The results of the research into the asexual reproduction of colonial rhizocephalan barnacles have been summarized. The colonial organization is unique not only among crustaceans and all other arthropods, but within the whole group of Ecdysozoa of bilateral multicellular animals. It has been shown that a rhizocephalan colony origins from nuclei appearing on the epithelial tube-like stolon. The stolon contains undifferentiated stem cells inside, which give rise to somatic and sex cells of blastozooids.

14. Immunochemical methods and electron microscopy were used to study the morphology of the nervous system in the tornaria, the larva of hemichordates, occupying a central position in phylogenetic schemes on deuterostome evolution. It has been demonstrated that the nervous system of the tornaria larva fundamentally differs from the nervous system of the echinoderm larvae in the distribution of serotonin- and FMRF-amide neurons and in some ultrastructural features.

15. The larvae of two abundant groups of meroplankton, decapods and cirripedes, of the Russian waters of the Sea of Japan have been studied in detail. A new dichotomous key was elaborated for the identification of crab larvae, including commercially important species. Identification keys were also developed for nauplial and cypris larvae settling on anthropogenic substrates.

16. A unique investigation was conducted into the arrangement of all systems of organs in nemerteans by use of electron and laser confocal microscopy. A new system of high taxa (orders and families) of nemerteans was elaborated based on new, previously neglected, characters. The evolutionary transformations of the body wall musculature, musculature of internal organs, proboscis, circulatory and digestive systems, and the system of sense organs were reconstructed. Possible phylogenetic relationships between the orders of Nemertea were determined. Studies of nemertean neurogenesis have confirmed that this phylum belongs to the Lophotrochozoa clade of metazoans.

17. A unique Sakhalin population of the western grey whale listed in the IUCN Red List was studied for several years. Data on the ecology and the mode of life of this whale have been summarized as a photo-ID catalogue of 135 individuals identified since 2002.

The laboratory conducts cooperative researches with:

– Lomonosov Moscow State University (comparative anatomy and embryology of nematodes, trochozoans, and phoronids);

– Severtsov Institute of Ecology and Evolution, Moscow (reproduction and life cycles of parasitic nematodes);

– Zoological Institute of the Russian Academy of Sciences (RAS), St. Petersburg (taxonomy and morphology of nemerteans and nematodes);

– Koltsov Institute of Developmental Biology of the RAS, Moscow (neurogenesis of bivalves and nemerteans);

– Sakhalin Research Institute for Fisheries and Oceanography, Yuzhno-Sakhalinsk (meroplankton of the Japan and Okhotsk seas);

– Institute of Ecology and Biological Resources of the Vietnamese Academy of Science and Technology, Hanoi, Vietnam, Hanoi, Vietnam (biodiversity and reproduction of marine nematodes);

– Ghent University, Ghent, Belgium (morphogenesis of nematodes);

– Paranб Federal University (Universidade Federal do Paranб), Curitiba, Brazil (biodiversity, reproduction, and larval development of polychaetes).

Since the establishment of the laboratory, its researchers have defended six dissertations for the Doctor of Sciences degree and 23 PhD dissertations. One researcher has been elected as Academician (full member), one as Corresponding Member of the Russian Academy of Sciences, four researches have been conferred the title of Professor and one of Associate Professor. Twenty-seven monographs (two of which are translated into English and published abroad) and more than seven hundred papers in peer-reviewed journals have been published. The laboratory have won twenty-six grants from the Russian Foundation for Basic Research, five grants from the Ministry of Education and Science of the Russian Federation, a prize, a medal, and two personal scholarships from the Alfred Toepfer Stiftung F.V.S. Foundation (Germany), two prizes from the MAIK Nauka / Interperiodica Publishing House for the best publications; three researchers have won the Russian Science Support Foundation nominations “Best Post-graduate Students” and “Best Candidates and Doctors of Sciences”; one post-graduate student has won a personal scholarship from the President of the Russian Federation.

Дата добавления: 2015-10-29