Structural-functional study of glycine-and-proline-containing peptides (Glyprolines) as potential neuroprotectors

A synthetic scheme for preparation of (Gly-Pro) _n , (Pro-Gly) _n (n = 2, 3), and (Pro-Gly-Pro) _n (n = 1, 2) peptides was elaborated. The effect of the synthesized peptides and the Gly-Pro and Pro-Gly dipeptides on survival of cultured cells of PC12 rat pheochromocytoma was studied under the conditions of oxidative stress induced by brief incubation of the cells with hydrogen peroxide. Peptides of the general formula (Gly-Pro) _n and the Pro-Gly-Pro peptide at a concentration of 0.2–100 μM were shown to decrease the number of damaged cells. The Gly-Pro peptide was the most active and decreased the number of damaged cells by 49% on average at a concentration of 100 μM.     

The expression of mutation sy2 causing nonhomologous synapsis in meiosis of diploid rye Secale cereale L

The cytological expression of spontaneous mutation sy2 isolated from a population of weedy rye was examined. It was demonstrated that the primary defect of meiosis in the mutant plants is nonhomologous synapsis, which occurs simultaneously with the homologous one. An electron microscope study of the synaptonemal complex (SC) at prophase I showed synaptic abnormalities that manifested as "switches" of synapting axial elements to the nonhomologous partner and the formation of foldbacks of lateral SC elements. The sy2 mutants are characterized by one to two such events per meiosis. Nonhomologous synapsis leads to the appearance of univalents at metaphase I (on average 4.16 +/- 0.022 per meiocyte) and multivalents (on average 0.12 +/- 0.007 per meiocyte). The presence of multivalents in 12.0% of meiocytes at metaphase I may result from recombination in ectopic regions of homology. It is suggested that the sy2 mutation impairs a component of the system that limits synapsis in meiocytes to only homologous chromosome pairs.     

Downstream migration in ammocoetes of the Arctic lamprey <Emphasis Type="Italic">Lethenteron camtschaticum</Emphasis> in some Kamchatka rivers

This paper considers the major patterns of downstream migration in Arctic lamprey ammocoetes in Kamchatka rivers. Ammocoetes of different age groups are shown to be constantly noted in the composition of the migrant part of a river community. The greatest intensity of downstream migration in ammocoetes of the age class 0+ is noted in the period of their primary dispersion in late July-early August. The ammocoetes of the age groups 1+ and older migrate from spring to late autumn, but their concentrations are not high. The significant similarity of such a biologic feature as downstream migration in ammocoetes and juvenile salmonids serves as an example of ecological analogy.     

Effect of triiodothyronine on aldolase metabolism in the liver of irradiated rats

The influence of different triiodothyronine doses on aldolase metabolism in rat liver was studied after whole-body X-irradiation. The effect of the hormone on the rates of synthesis and degradation and on the time of functioning of the enzyme in the exposed body was shown to vary markedly in the irradiated and intact animals.     

Synthesis of glycosaminoglycans in fibroblasts from abortuses with trisomy,triploidy, and from children with Down's syndrome

Summary A comparative study has been made of glycosaminoglycan (GAG) accumulation in human fibroblasts with trisomy 7 and triploidy from spontaneous abortuses, fibroblasts with triploidy from induced abortuses, fibroblasts from patients with Down's syndrome and diploid fibroblasts from age-matched controls. The study demonstrated that the incorporation of [³H]glucosamine into hyaluronic acid by fibroblasts with trisomy 7 and triploidy, established from spontaneous abortuses, and from two out of three induced abortuses with triploidy, was 2.6–5.3 times lower than control incorporation. One strain of fibroblasts from an induced abortus with triploidy (IMG-1062) did not show any differences in GAG production when compared with diploid fibroblasts. However, the strains from children with Down's syndrome revealed normal or even increased levels of hyaluronic acid production. The data support the contention that the decreased hyaluronic acid synthesis in fibroblasts with an abnormal karyotype is related to spontaneous abortion.     

Interspecific hybrids between Romanian and Kurdistan hamsters

From crossings between Mesocricetus brandti and Mesocricetus newtoni 23 hybrids were obtained which presented characters intermediate between the parents and which were completely sterile. The number of chromosomes in the hybrid animals (2n=40) is also intermediate between the parents and the karyotype presents two distinct chromosome sets corresponding to those in the two parent species. The regular presence of multivalents at diakinesis and metaphase I probably causes the non balanced disjunction of the genetic material, and thus, probably, the total sterility of the hybrids. The study of sex chromatin showed the existence of a sex dimorphism, the female presenting more nuclei with 1–2 sex chromatin bodies. The presence of 2 sex chromatin bodies of different sixes may be explained by the heteroehromatinization of a whole X chromosome and half of its homologue.Histological study showed that the male and female genital apparatus are intensively affected in hybrids and the spermatogenetic and oogenetic activity is generally stopped. This determines the total sterility of the hybrids.     

Human heart muscle proteins: two-dimensional electrophoretic analysis in embryos

Human myocardium proteins synthesized in the course of heart muscle development have been analyzed by two-dimensional electrophoresis. The quantitative change was found in representation of the main retractable proteins in the course of the heart muscle formation (the light myosin chains, tropomyosin, etc.). Four polymorphous variants of myocardium proteins were found, one of which is, possibly connected with the defect in heart development.     

Abnormal condensation of meiotic chromosomes caused by the mei8 mutation in rye Secale cereale L

Inheritance of two spontaneous meiosis-specific mutations with similar cytologic phenotype was studied. Both mutations were independently obtained from two rye populations (Vyatka variety and weedy rye). Both mutations are recessive, allelic, and monogenically inherited; the corresponding gene is designated mei8. The mutant alleles of the gene cause abnormal meiotic chromosome structure expressed as irregular compaction along the chromosome length, chromatin stickiness at all stages of meiosis, and chromosome fragmentation in anaphase I.