[Complex formation between recombinant protein VPg of potato virus Y and heterologous eukaryotic translation initiation factors eIF4E].

Genomes of some positive-strand RNA viruses do not contain cap-structure, but instead their 5'-end is covalently linked to a viral protein called VPg. Complex formation between VPg and cellular translation initiation factors (eIFs) has been extensively studied in the context of the model of this complex involvement in virus mRNA translation initiation and cellular protein translation shut down in infected cells. The potato virus (PVY) VPg was expressed in bacterial and baculovirus systems in order to investigate its binding capacity to wheat eIF4E and its isoform. Both purified recombinant eIF4E and eIF(iso)4E were identified in vitro as binding partners of the purified recombinant VPg by using affinity chromatography, as well in vivo by coexpressing of recombinant VPg and eIFs in insect cells with following complex purification using affinity chromatography. Besides it was shown that PVY VPg also formed a complex with endogenous insect eIF4E in vivo. PVY VPg interaction with eIF4E of wheat (non permissive plant for PVY), and also with so evolutionary distant partner as insect eIF4E suggests the conservation of general structural features of eIF4E implicated in the formation of the complex with VPg.

[The levels and nature of translation in mouse preimplantation embryos with repressed cytokinesis]. / Urovni i kharakter transliatsii u doimplantatsionnykh zarodyshei myshi s podavlennym tsitokinezom.

The translational activity of embryos cultured up to the 8-cell stage in cytochalasin D-supplemented medium was studied. These embryos remained unicellular during the entire preimplantation period. Blastocoel formation and hatching began in the cytochalasin-treated embryos at the same time as in the control. We have studied the overall translation rates of "one-cell embryos" and estimated the relative translational differences for individual polypeptides compared to the control embryos. Up to the early blastocyst stage, the translation levels in these embryos, measured by 35S-methionine incorporation, were about two times lower than in the control. At later stages, the differences were fivefold. The ppm values of approximately one-third of all individual spots on two-dimensional electrophoregrams differed three times or more between the control and cytochalasin-treated embryos. These results suggest that the first morphogenetic events in mammalian ontogenesis may be controlled autonomously and the timing of morphogenetic transitions is controlled by acquisition of a definite set of stage-specific factors which serves as the signal for subsequent development.

[Changes in the cavitation start time in chimeric CB6F1 <--> BALB/c embryos]. / Izmenenie vremeni zapuska kavitatsii u khimernykh zarodyshei CB6F1 <--> BALB/c.

It is found out that the acceleration of preimplantation morphogenesis is observed in mouse chimeras between single two-cell-stage blastomeres of BALB/c and [BALB/c x C57B1/6] x C57B1/6 (F2) embryos. The paired aggregation of blastomeres of two-cell stage made F2-BALB/c chimeras to start cavitation 8 +/- 2 hours earlier than F2<-->F2 and BALB/c-BALB/c control embryos. We have demonstrated for the first time the 'chimeric' heterosis on preimplantation stages. Possible approaches to the future studies of this phenomenon are discussed.

Mechanisms of cell number regulation in the peri-implantation mouse blastocyst.

Low viability of manipulated or in vitro cultured is caused primarily by the reduced cell number in the implanting blastocysts. In order to investigate the effect of implantation delay on embryo viability and cell number, mouse blastocysts were transferred into oviducts of day 0 pseudopregnant females. This type of transfer improved embryo survival rates, indicating that embryos retarded by in vitro culture restored their viability during 3 days of delayed implantation. Our results showed that even in the cases when the initial cell count was as low as 28.2 +/- 0.7 cells per blastocyst (vs 60.5 +/- 1.4 cells in the control blastocysts, developed in vivo), implantation delay increased this number to 107.2 +/- 3.5 cells (control blastocysts had at this stage on average 111.0 +/- 3.7 cells). Half-blastocysts, developed from the single blastomeres of the 2-cell embryos or from experimentally produced tetraploids, had around 50 cells after 3 days of implantation delay. This indicates that the start of blastocyst dormancy is triggered during the eighth cell cycle and independent of the absolute cell number or the number cytokineses. Implantation-delayed blastocysts, developed from the half-embryos with the doubled volume of cytoplasm, had on average 70.5 +/- 2.4 cells, suggesting that embryo fall into quiescence is also dependent upon the attainment of a definite nucleo-cytoplasmic ratio. We conclude that blastocyst readiness for implantation is determined by two factors: number of cell cycles and nucleo-cytoplasmic ratio.

[Heterologous protein expression in the baculovirus vector system: the nuclear polyhedrosis virus of Malacosoma neustria in Antheraea pernyi cells]. / Ekspressiia geterologichnykh belkov v bakulovirusnoi vektornoi sisteme: virus iadernogo poliédroza Malacosoma neustria--kletki Antheraea pernyi.

The results of the creation of new expressive system on Malacosoma neustria nuclear polyhedrosis virus and cell line originated from Antheraea pernyi tissues was demonstrated. The expression of bacterial beta-galactosidase-coding gene was analyzed in this system.

[The effect of chronic ionizing radiation at low doses on a number of reproductive indices in CC57W/Mv mice from an experimental Chernobyl population]. / Vliianie khronicheskogo ioniziruiushchego oblucheniia v malykh dozakh na riad pokazatelei reproduktivnoi funktsii myshei linii CC57W/Mv iz chernobyl'skoi éksperimental'noi populiatsii.

The effects of low doses of environmental ionizing radiation on reproductive functions of seven generations of CC57W/Mv mice from Chernobyl experimental population has been investigated. A decrease in the number of litters per female during reproductive period, the number of newborn animals per litter, and an increase in the postnatal mortality during the first month of life were shown. These effects are due to the stable disorders of parental reproductive system and the high level of in-vivo preimplantation deaths in F1--F7 generations of CC57W/Mv mice from the Chernobyl experimental populations.

[The nature of the distribution of the individual circulatory biorhythms in schoolchildren (7 to 17 years old) living at different altitudes in the mountains]. / Kharakter raspredeleniia individual'nykh bioritmov krovoobrashcheniia shkol'nikov (7--17 let), zhivushchikh na razlichnykh vysotakh gor.

Data on individual biorhythms are presented for 270 children aged 7-17 living in the regions situated at 760, 1700 and 2850 m above the sea level. Central hemodynamics was measured by Kubicek et al. method 6 times a day every 6 hours. The analysis of the pilot evidence was conducted by cosinor program, then an original method was introduced which allowed evaluation of the degree of biorhythmologic dispersion in the samples. The findings indicate a significant increase in hemodynamic biorhythm polymorphism and broadening of "biorhythmological norm" in children population aged 7-17 under the middle and high mountain conditions.

[The circadian rhythmicity of human orthostatic tolerance]. / Sutochnaia ritmichnost' ortostaticheskoi ustoichivosti cheloveka.

The results of studying the daily rhythmicity of orthostatic tolerance of blood system in practically healthy men are presented. The orthostatic test was performed 6 times a day with a 4-hour interval. The parameters of systemic, cerebral and peripheric hemodynamics have been recorded. It is found that a degree of a change in an intensity of cerebral blood supply experiences the marked variations depending on time of day. The day-night cycling of orthostatic tolerance of cerebral circulation is greatly determined by the biorhythm of the responses of arterial vessels of the lower extremities, i.e., by the natural periodization of blood redistribution processes. The highest orthostatic tolerance is noted at 3 to 11 a.m. and the lowest one at 3-7 p.m.

The role of the nucleocytoplasmic ratio in development regulation of the early mouse embryo.

The hypothesis suggesting that the blastocoele is able to form only at a definite nucleocytoplasmic ratio was tested. We compared the development of preimplantation mouse embryos under different conditions. The results demonstrated that the start of cavitation is not dependent on the number of cell divisions. Thus, a definite nucleocytoplasmic ratio is not required for blastocoele formation to start. Our studies on embryos with microsurgically altered cytoplasm content provided evidence for the following biological clock mechanism: a change in the cell program of morphogenesis needs definite concentration of the products of a previous genetic program.