Functional characteristics of light and dark cells]

Comparison of peculiarties attending the structure of mitochondria in the dark and light cells with the results of studying the respiration of condensed, intermediate and orthodoxic mitochondria showed that dark cells containing condensed mitochondria were at the state of rest or specific activity associated with a high level of bioenergetic and biosynthetic processes. Light cells with a preponderant content of intermediate mitochondria are characterized by the state of active specific activity accompanied by a high energy potential, intensified energy expenditure and a reduction of the level of biosynthetic processes. Light cells with a prevalence of orthodoxic mitochondria are characterized by a low level of energy provision and a predominance of the processes of decomposition of structures over their resynthesis.     

Introduction of active enzymes into intact Escherichia coli cells by means of liposomes. Phenotypic suppression of uvr A and pol A mutants

Summary Genetically deficient cells were supplied with the missing enzymes, purified from an independent source. The introduction of exogenous enzymes into the cells was effected by two independent methods: plasmolysis and liposome transformation. The latter procedure yielded a homogenous cell population which had been rescued from the defect even if the molecular weight of the enzyme amounted to 70 KD (Kilodaltons).     

Polymorphisms and Evolution of Solanum bulbocastanum Genes for Broad-Spectrum Resistance to Phytophthora infestans

Russian Journal of Plant Physiology - For two decades, Solanum bulbocastanum Dun. has been challenging potato geneticists with its durable resistance to Phytophthora infestans Mont. de Bary, the...     

The R1 gene for late blight resistance in early and late maturing potato cultivars

The method of polymerase chain reaction was used to amplify a fragment of the LZ-NBS-LRR receptor kinase gene R1; the gene was transferred into potato (Solanum tuberosum) from its wild-growing relative S. demissum and confers the race-specific recognition of the pathogen Phytophthora infestans. To verify this method as a test for the presence of the late blight resistance gene R1, the amplified genome fragment was cloned from the potato hybrid comprising the germplasm of S. demissum. The primary structure of this fragment, which corresponded to the receptor domain of kinase, did not practically differ from the matching sequence in S. demissum. In addition, the method was verified by scoring the set of plant differentials, wherein the presence of R1 was established with race-specific Phytophthora isolates. By screening 70 potato cultivars, we established a significant relationship between the presence of the gene R1 fragment and the phenotypic characters of late blight resistance and late maturity. This evidence supports the idea that R1 was introgressed from short-day S. demissum into potato plants together with some gene(s) conferring late transition to flowering.     

Temperature-induced radioresistance of Escherichia coli cells

A marked increase in radioresistance of E. coli cells, of the wild-type repair genotype, was observed when they were exposed to gamma-radiation at 40-45 degrees C. The effect of the thermoinduced radioresistance did not depend on the growth medium and the pre-incubation temperature but disappeared completely after treatment of cells by chloramphenicol or CaCl2 or after modification of cell membranes by exogenous cholesterol. This phenomenon was not observed with UV-irradiation. It is suggested that the thermoinduced radioresistance is connected with the activation of the membrane-associated repair complex.     

Two orthologs of late blight resistance gene <Emphasis Type="Italic">R1</Emphasis> in wild and cultivated potato

The R1 gene for resistance to oomycete Phytophthora infestans (Mont.) de Bary, the causal agent of late blight disease of potato (Solanum tuberosum L.), was initially identified in S. demissum and potato varieties bred by introgressing the S. demissum germplasm. Later a sequence characterized amplified region (SCAR) marker R1-1205 of this gene was also found in S. stoloniferum and S. polytrichon. Here we describe the full-length R1 sequence cloned from S. stoloniferum. This sequence is translatable, and this evidence of structural gene integrity is reinforced by functional characterization of the S. stoloniferum R1 gene in an effectoromics experiment. When screened across a series of S. demissum and S. stoloniferum accessions, the R1 sequences differed by several single nucleotide polymorphisms and an indel; this indel served the basis for constructing SCAR markers R1-517 and R1-513 that reliably discerned two R1 orthologs. The demissum-specific marker R1-517 was found in all S. demissum accessions under study; it was also present in many demissum-derived potato varieties and hybrids. The stoloniferum-specific marker R1-513 was found in 27% of S. stoloniferum and S. polytrichon accessions; however, we failed to discern this marker in the genotypes of cultivated potato listing S. stoloniferum in their pedigrees. Most probably, such absence of R1-513 is best explained by an opportunistic breeding history of stoloniferum-derived founder lines, which were employed first and foremost in breeding for resistance to potato virus Y: eventually, these founder lines are devoid of the R1 gene.     

Morphological bases of liver insufficiency in the early stages of the prolonged crush syndrome

Light and electron microscopies were employed to examine liver of 45 rats and 20 dogs under 6- and 9-hour compression of soft tissues of the thigh and 2 to 7 hours after pressure was taken off. Morphology of liver microcirculatory disorders is presented, the incremental derangement of the cells of the reticuloendothelial system (RES) with the appearance of the signs of its function depletion after decompression is described. Alterations in the liver RES correlated with destructive changes in hepatocytes and their necrosis. The morphological alterations in the liver RES in the crush syndrome reflect the impairment of its barrier function. They may play a role in the impairment of liver regeneration processes and immunological homeostasis of the host.     

Genetic determination and mechanism of realization of temperature-induced radioresistance

A study was made of the influence of the repair genotype of E. coli cells on the realization of the effect of enhanced radioresistance during gamma-irradiation at elevated temperatures (40-45 degrees C). The effect of the thermoinduced radioresistance (TIR) was diminished significantly but not abolished completely in mutant cells selectively deficient in excision or recombination repair systems (po1A1, recB21C22sbcB15, recF143 mutants). However mutations which exclude the recA gene product (recA13, recA13B21C22 or lexA3 mutants) inhibited TIR completely. The introduction of recA+ gene into recA- or lexA- mutants almost normalized TIR. On the basis of the data obtained the authors discuss the role of recA protein in activation of the membrane-associated repair complex whose efficiency depends on the temperature of gamma-irradiation.