Germinal granules in interstitial cells of the colonial hydroids <Emphasis Type="Italic">Obelia longissima</Emphasis> pallas, 1766 and <Emphasis Type="Italic">Ectopleura crocea</Emphasis> Agassiz, 1862

Electron-dense germinal granules, which are usually regarded as markers and key organelles of germline cells, were revealed in the interstitial (stem) cells of the colonial hydroids Obelia longissima and Ectopleura crocea. The interstitial cells of O. longissima displayed intense alkaline phosphatase activity, a histochemical marker for vertebrate embryonic stem and primary germ cells, as well as positive reaction to proliferating cell nuclear antigen (PCNA), which is an immunochemical marker for cell reproduction. Our findings and the literature data suggest the evolutionary conservation and similarity of the morphological and functional organization of potentially gametogenic stem cells in asexually reproducing invertebrates and germ cells in all studied Metazoa. The self-renewing pool of such stem cells provides the cellular source for blastogenesis and gametogenesis and the cellular basis for life functions, including both asexual and sexual reproduction.     

Capacity of bone marrow cells to restore thrombocytopoiesis in lethally irradiated animals

A study was made of the kinetics of thrombocytopoiesis restoration in lethally irradiated mice after transplantation to them of the donor marrow cells. In the initial period, the thrombocytopoiesis restoration is provided by transite cells-precursors of megakaryocytes present in the transplanted bone marrow; the subsequent restoration is due to cells of the self-maintaining population. The level of restoration does not correlate with the number of polypotent cells that form macrocolonies in the spleen of irradiated recipients.     

The effect of low-dose rate radiation simulating the high-altitude flight conditions on mice in vivo

In present work, we investigated the peculiarities of the effect of a low-dose rate high-LET radiation that simulates the spectral and component composition of the radiation field formed in the atmosphere at a height of 10 km on mice in vivo. The dose dependence and adaptive response were examined. Irradiation of mice was performed for 24 h a day in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons for the time (15-31 days) necessary to accumulate the required doses. The experiments demonstrated that irradiation of mice in vivo in the dose range of 11.5-31.5 cGy leads to an increase in cytogenetic damage to bone marrow cells and induces no adaptive response in bone marrow cells.     

Stem cells in reproductive strategy of asexually reproducing invertebrates

Original and literature data supporting the evolutionary conservation of the morphofunctional organization of totipotent cells of germ and stem lineages in metazoan animals are reviewed. We studied stem cells of the colonial rhizocephalans, Peltogasterella gracilis, Polyascus polygenea and Thylacoplethus isaevae, the turbellarian Dugesia tigrina, the colonial hydroid Obelia longissima, and cultured embryonic stem cells of mouse. The typical germinal granules of germ plasm, selective expression of the activity of alkaline phosphatase and of proliferating cell nuclear antigen (PCNA), which are known as markers of stem and primary germ cells of vertebrates, and the specific expression of the protein product of the vasa gene in cells of rhizocephalans, which is a marker of cells of germ and stem lineages of various metazoans, specified the stem cells of invertebrates of such different taxa. The self-renewing pool of totipotent stem cells is the cellular basis of the reproductive strategy, including sexual and asexual reproduction; such cells share morphofunctional features of embryonic stem and germline cells of Metazoa.     

Chromosome mutagenesis and cytogenetic monitoring]

A model of formation of radiation-induced cytogenetic damage is proposed on the basis of our own and literature data. The model postulates that localization of DNA damage and repair process play an important role in the final effect.     

Effect of secondary radiation from 70-GeV protons and gamma quanta on chromosomes of Chinese hamster cells as dependent on the cell cycle stage

In cultured Chinese hamster cells, no decrease in the number of chromosome aberrations was noted after exposure thereof to 70 GeV protons at the late S-phase as opposed to early one. It is suggested that high biological effectiveness of this type of radiation is associated with its inhibiting effect of cytogenetic damages repair.     

Cytogenetic effect of gamma quanta and secondary radiation generated by 70 GeV protons on Chinese hamster fibroblasts

The study of the cytogenetic effects (for instance, the chromosome aberration frequency in G2 cells and micronucleus formation) after exposure of Chinese hamster cells to gamma-rays and secondary radiation generated by 70 GeV protons showed that the relative biological effectiveness (RBE) of secondary radiation was approximately 3. The contribution of isochromatid deletions and exchanges into the total spectrum of rearrangements induced by the secondary radiation was different from that observed on gamma-irradiation. The absence of the modifying effect of caffeine on the cells exposed to the secondary radiation indicated that RBE of the secondary radiation from 70 GeV protons was mainly associated with its inhibitory action on the cytogenetic damages repair.     

Infestation Level of the Crab Hemigrapsus sanguineus by a Parasitic Crustacean Polyascus polygenea (Crustacea: Cirripedia) in Vostok Bay, Sea of Japan

We studied the infestation level of the coastal crab Hemigrapsus sanguineus by a cirripede barnacle Polyascus polygenea in Peter the Great Bay (Vostok Bay, Sea of Japan) in 1998–1999. It is shown that the externae of the parasite usually appear on the surface of the host’s body at the time when the crab attains sexual maturity (at a carapace width of 14–15 mm). More often we encountered infested crabs of a medium size, with a carapace width of 25–29 mm. The level of crab invasion did not depend on the sex of the host. In the summer period the proportion of infested crabs in different habitats ranged from 7 to 84%. The greatest number of crabs bearing the externae of the parasite was registered in an area with a boulder-pebble surface and small surf waves.Original Russian Text Copyright © 2005 by Biologiya Morya, Korn, Akhmadieva, Rybakov, Shukalyuk.