Medico-genetic study of the population of Kostroma Province. VI. The parameters of isolation by distance in the populations of the Bui and Shar'ya Districts of Kostroma Province

A model of isolation by distance proposed by Malécot and developed by Morton is applied to the data on marriage distances collected in two regions of Kostroma Province. There is good agreement between the estimates of local inbreeding when using the isonymy method and the model of isolation by distance. Interpopulation kinship approaches 0 at the distance 700 km. The mean coefficient of kinship for parents in the families with autosomal-recessive pathology is 20 times higher than mean coefficient of kinship in the population.     

Characterization of Pectobacterium carotovorum subsp. carotovorum Bacteriophage PP16 Prospective for Biocontrol of Potato Soft Rot

Microbiology - Phages of the phytopathogenic Pectobacteriaceae species causing black leg and soft rot of potato were investigated. These phages are promising as biocontrol agents to prevent the...     

Stepping transfer messenger RNA through the ribosome

tmRNA (transfer messenger RNA) is a unique molecule used by all bacteria to rescue stalled ribosomes and to mark unfinished peptides with a specific degradation signal. tmRNA is recruited by arrested ribosomes in which it facilitates the translational switch from cellular mRNA to the mRNA part of tmRNA. Small protein B (SmpB) is a key partner for the trans-translation activity of tmRNA both in vivo and in vitro. It was shown that SmpB acts at the initiation step of the trans-translation process by facilitating tmRNA aminoacylation and binding to the ribosome. Little is known about the subsequent steps of trans-translation. Here we demonstrated the first example of an investigation of tmRNA.ribosome complexes at different stages of trans-translation. Our results show that the structural element at the position of tmRNA pseudoknot 3 remains intact during the translation of the mRNA module of tmRNA and that it is localized on the surface of the ribosome. At least one SmpB molecule remains bound to a ribosome.tmRNA complex isolated from the cell when translation is blocked at different positions within the mRNA part of tmRNA.     

Effect of the temperature of oocyte maturation on the heat resistance of the body and cells in the progeny of the common frog

A study was made of the effect of low (4-5 degrees C) and high (17-22 degrees C) temperatures of oocyte maturation on different stages of development: a unicellular stage, early tadpole stage 39 and late tadpole, near the end of metamorphosis stage 52. Different temperatures in the course of oocyte maturation do not lead to reactive shifts in heat resistance of the organism and muscle cells of the progeny on either developmental stage examined.     

Structural features of the tmRNA–ribosome interaction

Trans-translation is a process which switches the synthesis of a polypeptide chain encoded by a nonstop messenger RNA to the mRNA-like domain of a transfer-messenger RNA (tmRNA). It is used in bacterial cells for rescuing the ribosomes arrested during translation of damaged mRNA and directing this mRNA and the product polypeptide for degradation. The molecular basis of this process is not well understood. Earlier, we developed an approach that allowed isolation of tmRNA–ribosomal complexes arrested at a desired step of tmRNA passage through the ribosome. We have here exploited it to examine the tmRNA structure using chemical probing and cryo-electron microscopy tomography. Computer modeling has been used to develop a model for spatial organization of the tmRNA inside the ribosome at different stages of trans-translation.     

Bodily heat resistance and polymorphism of liver esterases of grass frogs]

The determination of organismal heat resistance and qualitative composition of polymorphous liver esterases during heat acclimation (25 degrees) has been made on frogs Rana temporaria. During hybernation the most heat resistant frogs possess the homozygous allele of A2 esterase. Heat acclimation and the summer rise in temperature in nature lead to an increase in heat resistance of frogs and to the disappearance of selective advantage of animals possessing the isoenzyme of the A2A2 esterase. The functional homeostasis of populations can maintain biochemical polymorphism regardless of the selective advantage of individuals possessing one of the homozygous alleles of the isoenzyme.     

Effect of thermal selection of the male gametes on the resistance to temperature and chlorophos of the body and muscles in tadpoles of the common frog

A study was made of the effect of thermal selection of parental spermatozoa on the heat resistance of the whole organism and of muscles in progeny of Rana temporaria, as well as of the organismal resistance to pesticides (0.0025 M chlorophos). The thermal selection of spermatozoa was performed by exposing their suspension to 36 degrees C for 30-40 minutes. With tadpoles, the resistance of muscles to 38 degrees C, was determined, in addition to the resistance of the organism to 34 degrees and to 0.0025 M chlorophos. The results of selection were stage--specific: at stages of growth (stages 39, 42, 50) the heat resistance of the organism was lower and that of muscles was higher than in controls. At the stage of metamorphosis proper (stage 52) the heat resistance of both the organism and muscles increased. The thermal selection of parental spermatozoa exerted no effect on the resistance of the progeny to 0.0025 M chlorophos.     

Correlation between the heat resistance of the provisional and definitive muscle tissue during the metamorphosis crisis in frogs

Using tadpoles of the lake frog Rana ridibunda Pall. during metamorphosis, a study was made of the heat resistance of the provisional muscle tissue of the tail and of that of two definitive muscles belonging to low-resistant (musculus iliofibularis) and high-resistant (musculus gastrocnemius) groups. It has been shown that during the late metamorphosis a statistically significant direct relation exists between the heat resistance of the provisional muscle tissue of the tail and definitive m. iliofibularis. A comparison with the earlier published data points to a positive correlation between each of these two characteristics and the survival of larvae at high injurious temperature.     

Nuclear envelope of frog diplotene oocytes has telomere-binding activity]

A telomere-binding activity was found in the nuclear envelope of frog oocytes Rana temporaria by methods of binding on nitrocellulose filters and retardation. At present it is hardly possible to detect the proteins responsible for this activity. However, the results of this study allowed us to identify a specific mechanism of DNA-protein interaction, which provides the binding of the telomere to the envelope in meiotic cells.     

<Emphasis Type="Italic">Trans</Emphasis>-translation: Findings and hypotheses

Trans-translation is a unique process that switches the synthesis of a polypeptide hain encoded by a nonstop mRNA to the mRNA-like domain of tmRNA. The process is used in bacterial cells for rescuing the ribosomes arrested during translation of nonstop mRNA and directing this mRNA and the polypeptide product for degradation. Activity of tmRNA is essential for bacterial survival under adverse conditions, the quality control of translation, and the regulation of certain physiological pathways. The review focuses on recent advances in trans-translation studies. Details of the tmRNA-SmpB interaction and the structures of early ribosomal complexes are characterized, the causes of the appearance of an empty A site in the translating ribosome and possible mechanisms of the stalled ribosome recognition and resume codon determination are discussed, and the proteins degrading nonstop mRNAs and tagged peptides are considered.