[Comparative analysis of the secondary structures of the high molecular weight large subparticle RNA of bacterial, fish, bird, and mammalian ribosomes].
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Animals↗
Biomedical subjects
K G Gazarian
Publications and source records attributed to K G Gazarian.
[Immunochemical analysis of histone H1 and H5 from pigeon erythroid cells].
An antiserum with the antibody titer of 1 : 4096 was obtained by immunization of rabbits with the tRNA-histone H5 complex from pigeon erythrocytes. The specificity of the antiserum was studied quantitatively from the reaction of the complement binding to a homologous antigen (histone H5) and its modifications (I, II, III), differing in the degree of phosphorylation. It was shown that phosphorylation of histone H5 increases the ability of the antigen to bind to antibodies, which is especially well-pronounced at the antiserum dilutions as high as 20480. The comparison of the antigenic properties of histones H5 from pigeon and chicken erythrocytes revealed beside structural differences of the proteins the presence of common antigenic determinants. A similar observation was made when histones H5 and H1 from pigeon erythrocytes were compared. Histone H1 from chicken erythrocytes and histone H1 from calf thymus did not produce criss-cross reactions with antiserum H5.
Animals↗
[Molecular organization and genome expression in eukaryotes].
The recent data on the structural organization and expression of genome in eukaryotes are reviewed. Different types of nucleotide sequences (repetitions, palindromes, homopolymers) represented in the regions of genome transcription, as well as in mRNA's of the cytoplasm and nuclear messenger-like RNA's are analyzed. Probable functions of different types of sequences are discussed. The problem of nuclear precursors of cytoplasmic mRNA's and in particular heterogeneous nuclear RNA is considered. It is noted that this population of molecules is heterogeneous not only by the molecular weight, but also by some other parameters. Stable messenger-like 28S and 18S RNA's found in the nuclei are described. In addition to the already known scheme of rapid posttranscriptional processing of pre-mRNA, a hypothesis is put forward to the effect that the selective transport of mRNA molecules stored in the nucleus from the nucleus into the cytoplasm is realized at the expense of extended processing.
Animals↗
[Transplantation of somatic nuclei into activated teleost eggs (the example of the loach, Misgurnus fossilis L.)].
Some peculiarities of the technique of nuclear transplantation for teleostean fishes are described, the loach (Misgurnus fossilis) taken as an example. The cells of the late high blastula were used as donors and the activated non-enucleated and enucleated (by X-rays, 20 kR) eggs of the loach as recipients. Following the nuclear transplantation in the activated non-enucleated eggs, 33 (out of 128) normal blastulae were obtained, one of which developed until hatching. Following the nuclear transplantation in the activated enucleated eggs, 34 (out of 251) blastulae were obtained, 6 embryos hatched and 2 larvae attained the stage of active feeding.
Animals↗
[Structure of the mRNA of eukaryotic cells].
A review is given of the principal achievements in studying the structure of mRNA in eukaryotic cells. The data are provided on the size and life time, complexity and distribution of different kinds of mRNA by the frequency of repetitions; composition and structure of mRNP. The structures of individual mRNA's and general pattern of the structure of eukaryotic mRNA and mRNP are considered.
Animals↗
[Mechanism of genome inactivation in avian erythrocytes. IV. New data on the mechanisms of cytodifferentiation in erythropoiesis].
In was shown earlier (Gazaryan & Kulminskaya, 1975; Kulminskaya & Gazaryan, 1976) that under the conditions of anemia a new (reserve) mechanism of the terminal differentiation of erythroid cells was induced. It was now found that in the course of cell development along this path the basophylic erythroblasts doubled the amount of DNA passed in the peripheral blood where they transformed into basophylic, polychromatophylic and orthochromic reticulocytes. Thereafter they entered the mitosis and transformed into the mature erythrocytes with diploid nuclei. It was shown for the first time that the cell delayed in the G2 phase could actively accumulate the specific product (hemoglobin) and keep its ability to enter the mitotic division.
Animals↗
["Extracyclic" DNA synthesis and the accumulation of total protein and hemoglobin in erythroid series cells in anemia in pigeons].
Two types of biosynthetic processes associated with cytodifferentiation underlie the "reserve" erythropoiesis of pigeons during anemia: 1) cells rapidly increase their nuclear DNA amount up to the level of 4c, whereas the total protein remains at the initial level; furtheron, cells double also their protein amount, and then enter into the phase of differentiation and specialization; after having hemoglobin accumulation they divide; 2) a limited increase of DNA amount takes place up to the level not exceeding 130% of the initial level; in this case a synchronous increase of the hemoglobin amount is detected in the cell. The first type processes provide the accumulation of the specific product and the accelerated increase of the number of erythrocytes in the population. The second way is aimed only to the accumulation of the specific product in a greater amount.
Anemia↗
[Polyuridylic sequence in pigeon globin mRNA].
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Animals↗
[Reactivation of the nuclei of reticulocytes and erythrocytes in heterokaryons].
The reactivation of the nuclei of erythrocytes, reticulocytes and bone marrow cells has been studied by means of hybridization of the pigeon erythroid cells with the human embryonic cells A1. The process of reactivation of the erythroid nucleus was shown to depend on the stage of erythroid cell differentiation. The nuclei of cells at the earlier stages of differentiation give a higher percentage of heterocaryons (40%, 70%) than those of more mature cells (9%). The activated nuclei of immatur cells formed nucleoli already 24 hrs, whereas those of mature erythrocytes only 3-5 days after the cell fusion.
Animals↗
[Pathways of terminal erythrocyte differentiation in birds. An analysis of the intermediate forms].
The erythropoiesis during anemia is characterized by the reduction of the bone marrow period of cell development. Two immature forms, absent in the normal state, were shown to be present under anemia: basophilic erythroblasts and reticulocytes with basophilic cytoplasm. These forms are interposed between the bone marrow basophilic erythroblasts and erythrocytes. Some basophilic erythroblasts turn out in the peripheral blood and transform into basophilic reticulocytes there. The level of transcription in anemic animals during the transformation of basophilic erythroblasts into basophilic reticulocytes does not decrease and is higher than that in polychromatophilic erythroblasts. The total chromatin condensation does not reflect the decrease of the transcription level.
Anemia↗
[Role of integrity of the inner nuclear membrane in energy supply for protein synthesis in the isolated cell nuclei of the salivary glands of Chironomus plumosus].
Using isolated nuclei of salivary grand cells of Chironomus plumosus larvae, it was revealed that the integrity of nuclei was a necessary condition for realization of protein synthesis in the nuclei. The involvement of nuclear particles in the above synthesis is supposed.
Amino Acids↗
[The problem of intranuclear protein synthesis].
This review deals with the analysis of the conflinting situations that appear during the study of the translational apparatus in cell nuclei. Experimental approaches used to unravel this problem are surveyed.
Amino Acids↗
[New information on the structure of eukaryote mRNA].
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Animals↗
[New information on the structure of eukaryote mRNA].
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Animals↗
[Metabolically stable classes of nuclear messenger-like RNA. I. Detection and molecular characterization].
Two discreet in size molecular classes of metabolically stable messenger-like RNA molecules with sedimentation coefficientes about 28S and 18S have been revealed in the nuclei of pigeon bone marrow cells. The structural pecularities of 28S RNA class were investigated more carefully. It was shown to constitute the largest fraction of nuclear messenger-like RNA and is characterized by a GC/AU ratio 1.13. As pulse-labeled nuclear RNA, 28S stable nuclear RNA hybridizes with the unique and rare repeated DNA, it does not contain poly(A)-sequences and is found in a form of RNP particles with density of 1.41 g/sm3, tightly bound to chromatin.
Animals↗
[Metabolically stable classes of messenger-like nuclear RNA. II. Existence of homology between the 28S fraction of nuclear RNA, giant non-polyadenylated molecules of heterogeneous nuclear RNA and polyadenylated molecules of cytoplasmic RNA].
The existence and extent of homology between the 28S fraction of messenger-like nuclear RNA on one hand, and giant (greater than 45S) molecules of heterogeneous nuclear RNA and various fractions of cytoplasmic RNA on the other hand were studied by the method of competitive hybridization. The results obtained lead to the conclusion that the poly(A)-subfraction of hnRNA molecules with the size of greater than 15 000 nucleotides contains molecules subjected to rapid but incomplete processing with the formation of chains approximately 5000 nucleotides long (approximately 28S), which are then stored in the nucleus for up to 30 hours. Later polyadenylated and non-polyadenylated molecules of cytoplasmic RNA with the size of less than or equal to 2000 nucleotides are formed from the stored precursors.
Animals↗
[Molecular structure of pigeon genome. Revealing of clusters consisting of prolonged homopolymeric and short palindromic sequences].
Isolated from pigeon genome short (approximately 450 nucleotides) and long (approximately 8000 nucleotides) single-stranded DNA fragments containing prolonged (greater than or equal to 300 nucleotides) polydeoxyandenylic sequences have been studied. Based on the analysis carried out we come to the conclusion that for the pigeon genome the prolonged poly(dA)-sequences are located as clusters where a large amount of short palindromic sequences occur.
Animals↗
[Reassociation of interspersed moderate DNA repeats].
Reassociation kinetics of the fragments of DNA consisting of interspersed repetitive and non-repetitive nucleotide sequences is considered in this paper. Based on the model, suggested by Gavrilov and Mazo (Mol. biol., 11, 101 1977), which takes into account the random DNA shearing, both reassociation kinetics of the total DNA in the region corresponding to interspersed repeat reassociation and that of the isolated preparation of interspersed repetitive sequences are calculated. In both cases influence of the repeat length on the reassociation rate is demonstrated. The estimation of the repetition frequency of rare repeats from pigeon genome is specified using calculations performed.
Animals↗