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Biomedical subjects

N N Rott

Publications and source records attributed to N N Rott.

At least 19 recordsLinked to original sources
PubMed1993

[Creation of a European bison sperm cryobank as a method for preserving the genetic polymorphism of the species].

Sperm was taken from one alive (by electroejaculation) and two dead (from epididymis tissue) wisent males, and was conserved by the method similar to that used to freeze sperm from cattle. Spermatozoon mobility and acrosome conditions underwent no noticeable changes when kept under preservation. Eight cows were fertilized with the sperm which had been kept in liquid nitrogen for three years. Four of them had hybrid calves. We also made genetic analysis for bull-donors: on blood groups, isoenzyme systems and the protein spectrum of blood serum and muscle tissue. The analysis revealed the rare antigene H' in one of the bulls and polymorphism in two isoenzyme systems in the other one. The results of the analysis proved that these animals can make valuable contribution to the developing genetic cryobank.

Acrosome↗
PubMed1979

[Cell cycles in the early embryogenesis of the peled].

The dynamics of cell cycles in early embryogenesis of the peled has been studied using various methofs: determination of mitotic and mitotic phase index, of cell doubling time and of coefficient of asynchrony. The desynchronization of divisions begins at the V division after the longitudinal furrow has passed and is completed after the beginning of the cell cycle lengthening. The animal-vegetative gradient in the distribution of mitotic phases is observed at the early stages of desynchronization. The lengthening of cell cycle begins in interphase of the XI-XII cleavage and markedly accelerates from the interphase of the XII-XIII cleavage on. The methods of analysis of the cell cycles in early embryogenesis and possible factors influencing the dynamics of desynchronization are discussed.

Animals↗
PubMed1978

[Development of isolated loach blastoderm during cultivation in different salt media].

The loach blastoderms were isolated from the yolk during the periods of cleavage and blastulation (5--14.5 tau0) and incubated in various isotonic saline media which differed by the content of K+ and Na+. The survival of blastoderms upon the short-term incubation (up to 60 tau0) varied insignificantly in all the media and upon the longer one (up to 120 tau0) was the maximal in the medium with isotonic content of K+ and Na+ and the minimal in the medium with the low content of K+. The cell proliferation upon incubation in the medium with the low content of K+ was inhibited when the blastoderms were isolated at the stage of 8 tau0 and suffered no changes at the stage of 14 tau0. The ability of differentiation manifested itself earlier and the percentage of differentiated embryos was higher in the media with the high content of K+. The content of K+ in the blastoderms isolated at the stage of 7 tau0 changes with its content in the incubation medium; upon isolation at the stages of 8--9 tau0 to blastoderms accumulate K+ irrespective of its content in the medium and at the stage of 10 tau0 maintain the constant level of K+. Hence, the development of isolated blastoderms depends on the content of K+ in the medium and this dependence reduces with the age.

Age Factors↗
PubMed1978

[Relationship between the phases of mitosis in the cells of chimeric loach embryos].

The loach embryos differing in age by 0.5 tau0 (tau0--duration of the mitotic cycle during the synchronous cleavage divisions) were combined in pairs at the stage of 4--8 blastomeres to elucidate the role of intercellular relationships in the preservation of cell division synchrony during cleavage. Following the incubation during 3 tau0 the mean value of interval between mitotic phases in the pairs of combined embryos somewhat decreased but this phenomenon cannot be considered as the proof of cell division synchronization due to the intercellular relationships since it was observed to the same extent in all groups of chimaeric embryos irrespective of the degree of fusion as well as in the control embryos.

Animals↗
PubMed1977

[Desynchronization of cell division during the early development of the axoloty, loach and salmon].

Patterns of a relative measure of asynchrony R of the cell population have been studied by means of a mathematical model of the kinetics of cell population which allows to follow the distribution of cells by the mitotic cycle phases in time. The application of the criterion R for the analysis of the patterns of desynchronization of cell divisions in the early embryogenesis of axolotl, loach and salmon has shown, that, unlike the smooth change of the asynchrony measure in the model populations with one constant factor desynchronization, the desynchronization in the species in question proceeds step-wise and runs to 3 steps. The problem of relationship between desynchronization and cytoplasmic segregation, decrease of electric coupling among cells and rearrangement of cell cycle is discussed. It was shown that the latter might occur in different species at a different degree of desynchronization.

Ambystoma↗
PubMed1976

[Obtaining chimeric embryos of groundling for study of the role of cellular interactions in early development].

A methos of production of chimaeric embryos of the loach by parabiosis of whole embryos and a whole embryo and an isolated blastodisc is proposed. The parabiosis was shown to be possible between the embryos of both the same and different ages during cleavage and blastulation. The relation between the frequency of parabiosis and the age of embryos and temperature was studied. An electric coupling is established between the cells of parabionts, similar by its value to that between the cells of each parabiont. The interrelations of cells of chimaeric embryos are considered as a model for studying the role of cell interactions during embryogenesis.

Animals↗
PubMedDate not supplied

[New data on nuclear transplantation in mammals].

The results of studies on nuclear transplantation in mammals published in 1986 allow to suppose the causes of failure in experiments on mice and outline ways of overcoming these difficulties.

Animals↗