Entry of facultative pathogen <Emphasis Type="Italic">Serratia grimesii</Emphasis> into Hela cells. Electron microscopic analysis

Facultative pathogens Serratia grimesii are able to invade eukaryotic cells where they have been found in vacuoles and free in the cytoplasm (Efremova et al., 2001; Bozhokina et al., 2011). However, efficiency of this invasion is low, and the mechanisms of the invasion related to the initial steps of the process are not known. In the present study, we have increased the invasion efficiency by a 24-h-incubation of HeLa cells with N-acetylcysteine (NAC) preceding the infection. In the NAC-pretreated cells, two modes of S. grimesii to enter HeLa cells were observed. In the most cases, the penetration of S. grimesii into the cell was consistent with the “zipper mechanism”, which first step involves specific interaction of bacterial invasin with a host cell surface receptor. However, in some cases, bacteria were trapped by filopodia probably induced by injected bacterial proteins that trigger the bacterial uptake process, as described in the “trigger mechanism” of invasion. To clarify whether two different mechanisms or a predominant one operate during S. grimesii invasion, further elucidation of bacterial and cellular factors involved in the bacteria-host cell interaction should be performed.     

Marker-Dependent Recombination in T4 Bacteriophage. II. the Evaluation of Mismatch Repairabilities in Crosses within Indicator Distances

The contribution of mismatch repair to genetic recombination in T4 phage has been evaluated by three independent approaches: (1) testing for non-additivity of recombinant frequencies; (2) measurements of double exchange frequencies in three-factor crosses: (3) comparisons of recombination abilities of mutations occupying the same site. Quantitative agreement among the results of these approaches suggests that within distances much less than the mean length of hybrid regions, mismatch repair accounts perfectly for high negative interference as measured in three-factor crosses and as manifested by non-additivity in two-factor crosses. The mismatch repair mechanism readily recognizes only particular mismatches, the repair frequency being dependent on the base sequence in both strands of the mismatched region.     

Cellular and humoral immunity factors in salmonellosis and food toxinfections

The present work deals with the state of cell-mediated and humoral immunity in 129 patients with salmonellosis and 185 patients with alimentary toxicoinfections, determined from the data obtained in the leukocyte migration inhibition (LMI) test and the passive hemagglutination (PHA) test with cysteine, at different stages of the disease and depending on the severity of the infectious process. The results of these investigations showed that in adult salmonellosis patients the specific reaction of T- and B-lymphocytes developed as secondary immune response. The results of the LMI test proved to be unrelated to the severity of the infectious process, while antibody formation was found to be most intensive in the acute course of the disease. The investigations also revealed that the activity of reaction in the LMI est did not depend on the presence of humoral antibodies. In the patients with alimentary toxicoinfections changes in the results of the LMI test and the PHA test with cysteine showed the same regularities as in the salmonellosis patients. This permitted the authors to suggest that diseases of Salmonella etiology prevailed in the former group.     

Production of alloplasmic and euplasmic wheat-barley ditelosomic substitution lines 7H<Superscript>1</Superscript>L<Superscript>mar</Superscript>(7D) and analysis of the 18S/5S mitochondrial repeat in these lines

Alloplasmic lines of common wheat with disomic substitution of chromosome 7D for telocentric chromosome 7H¹L^mar of barley H. marinum subsp. gussoneanum Hudson were isolated from the plants of generation BC₃, produced as a result of backcrossing of barley-wheat hybrids H. marinum subsp. gussoneanum (2n = 28) × T. aestivum (2n = 42), Pyrotrix, cultivar, with 28 common wheat cultivars Pyrotrix 28 and Novosibirskaya 67. Chromosome substitution pattern was determined using SSR analysis and C-banding. In preliminary genomic in situ hybridization experiments, telocentric chromosomes were assigned to wild barley was established. In the BC₃F₈ generations of three alloplasmic lines with the 7H¹L^mar(7D) substitution type the differences in fertility manifestation were observed: most of the L-32(1) plants were sterile, in line L-32(2) only sporadic plants were sterile, and line L-32(3) was fertile. Simultaneously with these experiments, using selfpollinated progeny of the hybrids obtained in crosses of common wheat cultivar Saratovskaya 29 (2n = 41), monosomic for chromosome 7D, with common wheat cultivar Pyrotrix 28 with addition of pair of telocentric chromosomes 7H¹L^mar (7D) of barley H. marinum subsp. gussoneanum, euplasmic wheat-barley ditelosomic substitution 7H¹L^mar (7D) lines were isolated. The lines obtained had normal fertility. PCR analysis of the 18S/5S mitochondrial repeat (hereafter, mtDNA sequence) in alloplasmic and euplasmic ditelosomic substitution lines 7H¹L^mar(7D) was performed. In the plants from alloplasmic sterile line L-32(1), the sequences only of the barley (maternal) type were revealed, while the plants from alloplasmic fertile lines L-32(2) and L-32(3) demonstrated heteroplasmy (the presence of barley- and wheat-like sequences within one individual). In euplasmic ditelosomic substitution lines the presence of only wheat-like 18S/5S mitochondrial repeat sequences was observed. The results indicate that the presence of barley-like mtDNA sequences in alloplasmic substitution lines was not associated with the presence of barley chromosomes in their nuclear genomes.     

Prevalence of <Emphasis Type="Italic">VRN1</Emphasis> locus alleles among spring common wheat cultivars cultivated in Western Siberia

With the use of allele-specific primers developed for the VRN1 loci, the allelic diversity of the VRN-A1, VRN-B1, and VRN-D1 genes was studied in 148 spring common wheat cultivars cultivated under the conditions of western Siberia. It was demonstrated that modern Western Siberian cultivars have the VRN-A1a allele, which is widely distributed in the world (alone or in combination with the VRN-B1a and VRN-B1c alleles). It was established that the main contribution in acceleration of the seedling–heading time is determined by a dominant VRN-A1a allele, while the VRNA1b allele, on the contrary, determines later plant heading. Cultivars that have the VRN-A1b allele in the genotype are found with a frequency of 8%. It was shown that cultivars with different allele combinations of two dominant genes (VRN-A1a + VRN-B1c and VRN-A1a + VRN-B1a) are characterized by earlier heading and maturing.     

Structural and functional analysis of new plant promoter pro-SmAMP1 from <Emphasis Type="Italic">Stellaria media</Emphasis>

The nucleotide sequence of a fragment of the promoter region of pro-SmAMP1 gene, having a length of 1257 bp and encoding antifungal peptides, was determined in chickweed (Stellaria media (L.) Vill.). Computer analysis of the nucleotide sequence revealed a number of cis-elements that are typical strong plant promoters. Five 5′-deletion variants were created taking into account the distribution of cis-elements:–1235,–771,–714,–603, and–481 bp of pro-SmAMP1 gene promoter, which were fused to the coding region of the uidA reporter gene in pCambia1381Z plant expression vector. The efficacy of pro-SmAMP1 promoter deletion variants was determined by transient expression in plants of Nicotiana benthamiana and using sequential generations of transgenic Nicotiana tabacum plants. It was found that the levels of GUS reporter protein activity in the extracts from transgenic and agroinfiltrated plants using all deletion variants of pro-SmAMP1 gene promoter were 3–5 times higher than those of 35S CaMV viral promoter. The highest activity of GUS protein was observed in the leaves of transgenic tobacco plants and closely correlated with the mRNA level of encoding gene. The levels of GUS activity did not differ significantly among 11 independent homozygous lines of T₂ generation of N. tabacum plants with different deletion variants of pro-SmAMP1 promoter. The results give reason to assume that all deletion variants of pro-SmAMP1 promoter provide stable and high level of expression of controlled genes. The shortest deletion variant–481 bp of pro-SmAMP1 promoter should be viewed as a potentially strong plant promoter for the genetic engineering of plants.     

Analysis of spike productivity traits in near-isogenic lines of the common wheat cultivar Saratovskaya 29 carrying alien marker genes

Six near-isogenic lines of the wheat cultivar Saratovskaya 29 carrying five marker genes from different species (Triticum compactum L., T. polonicum L., T. petropavlovskyi Udacz. et Migusch., Aegilops elongatum Host. and Secale cereale L.) were studied. It was shown that the introduced marker genes of taxonomic significance, C and P, have strong pleiotropic effects on quantitative traits of the spike productivity.     

The distribution and evolutionary history of the PRP8 intein

Background  

We recently described a mini-intein in the PRP8 gene of a strain of the basidiomycete Cryptococcus neoformans, an important fungal pathogen of humans. This was the second described intein in the nuclear genome of any eukaryote; the first nuclear encoded intein was found in the VMA gene of several saccharomycete yeasts. The evolution of eukaryote inteins is not well understood. In this report we describe additional PRP8 inteins (bringing the total of these to over 20). We compare and contrast the phylogenetic distribution and evolutionary history of the PRP8 intein and the saccharomycete VMA intein, in order to derive a broader understanding of eukaryote intein evolution. It has been suggested that eukaryote inteins undergo horizontal transfer and the present analysis explores this proposal.