Altered chromatin landscape in circulating T follicular helper and regulatory cells following grass pollen subcutaneous and sublingual immunotherapy

1. Download : Download high-res image (285KB)
2. Download : Download full-size image

     

Homologous recombination in the fission yeast Schizosaccharomyces pombe: different requirements for the rhp51+, rhp54+ and rad22+ genes

The Schizosaccharomyces pombe rhp51 ⁺ , rad22 ⁺ and rhp54 ⁺ genes are homologous to RAD51, RAD52 and RAD54 respectively, which are indispensable in the recombinational repair of double-strand breaks (DSBs) in Saccharomyces cerevisiae. The rhp51Δ and rhp54Δ strains are extremely sensitive to ionizing radiation; the rad22Δ mutant turned out to be much less sensitive. Homologous recombination in these mutants was studied by targeted integration at the leu1-32 locus. These experiments revealed that rhp51Δ and rhp54Δ are equally impaired in the integration of plasmid molecules (15-fold reduction), while integration in the rad22Δ mutant is only reduced by a factor of two. Blot-analysis demonstrated that the majority of the leu⁺ transformants of the wild-type and rad22Δ strains have integrated one or more copies of the vector. Gene conversion events were observed in less than 10% of the transformants. Interestingly, the relative contribution of gene conversion events is much higher in a rhp51Δ and a rhp54Δ background. Meiotic recombination is hardly affected in the rad22Δ mutant. The rhp51Δ and rhp54Δ strains also show minor deficiencies in this type of recombination. The viability of spores is 46% in the rad22Δ strain and 27% in the rhp54Δ strain, as compared with wild-type cells. However, in the rhp51Δ mutant the spore viability is only 1.7%, suggesting an essential role for Rhp51 in meiosis. The function of Rhp51 and Rhp54 in damage repair and recombination resembles the role of Rad51 and Rad54 in S. cerevisiae. Compared with Rad52 from S. cerevisiae, Rad22 has a much less prominent role in the recombinational repair pathway in S. pombe. Received: 20 July 1996     

Genetic and cytological characterization of the RecA-homologous proteins Rad51 and Dmc1 of Schizosaccharomyces pombe

The Schizosaccharomyces pombe rad51⁺ and dmc1⁺ genes code for homologues of the Escherichia coli recombination protein RecA. Deletion of rad51⁺ causes slow growth, retardation of cell division and a decrease in viability. rad51 cells have a defect in mating-type switching. The DNA modification at the mating-type locus required for mating-type switching contributes to slow growth in the rad51 mutant. Cell mating is reduced in crosses homozygous for rad51. Ectopic expression of the dmc1⁺ gene allowed us to demonstrate that the reduction in meiotic recombination in dmc1 mutants is not caused by a disturbance of rad24 expression from the dmc1-rad24 bicistronic RNA. We describe the functional defects of terminally epitope-tagged Dmc1 and Rad51 and discuss it in terms of protein interaction. Presumptive Rad51 and Dmc1 foci were detected on spreads of meiotic chromatin.     

诺如病毒衣壳蛋白重组人3型腺病毒的构建

目的 制备表达诺如病毒衣壳蛋白的重组人3型腺病毒.方法 将诺如病毒衣壳蛋白基因(Noro-orf2)克隆到腺病毒穿梭载体pBSE3CMV-egfp上,与线性化人3型腺病毒骨架质粒pBRAdv3共电转化感受态大肠杆菌BJ5183,使其在细菌内发生同源重组,带Noro-orf2基因的表达框置换腺病毒E3区,PCR及酶切筛选得到重组腺病毒质粒,将重组腺病毒质粒转染Hep-2细胞进行包装,获得感染性的重组腺病毒粒子,免疫组化分析重组腺病毒中诺如病毒衣壳蛋白的表达.结果 同源重组后经酶切和PCR鉴定证明插入Noro-orf2基因的重组腺病毒质粒pBRAdv3E3dNor成功构建,并经转染包装得到高滴度的重组腺病毒Adv3E3dNor,免疫组化证明诺如病毒衣壳蛋白得到表达.结论 成功构建表达诺如病毒衣壳蛋白的重组3型腺病毒Adv3E3dNor,为研制人3型腺病毒-诺如病毒双价疫苗奠定了基础.     

Allergic conversion of protective mucosal immunity against nasal bacteria in patients with chronic rhinosinusitis with nasal polyposis

1. Download high-res image (155KB)
2. Download full-size image

     

The value of deletion analysis for carrier detection in Duchenne muscular dystrophy (DMD)

We performed genetic analysis for carrier detection for several at-risk females in a four-generation Duchenne muscular dystrophy (DMD) pedigree using deletion analysis. We demonstrated that dosage analysis is a suitable alternative method to determine the carrier status of female relatives of DMD patients shown to have a deletion within the DMD gene. Subsequently, we diagnosed an affected male fetus for an at-risk female shown to be a DMD carrier by deletion analysis. The usefulness of deletion and linkage analysis are compared. In this family, linkage analysis was complicated by the unavailability of key family members, two recombination events and by previously undisclosed nonpaternity. We found that dosage analysis was more efficient than linkage for carrier evaluation in this family.     

High-frequency inter-parental recombination between mitochondrial genomes of rice cybrids

Analyzing more than 100 independent rice cybrids, we found evidence for inter-molecular recombination between parental mitochondrial genomes occurring at high frequency soon after protoplast fusion. The structure of the region around the atp6 gene showed extensive polymorphism among Indica (MTC-5A), Japonica (Nipponbare), and wild abortive (IR58024A) mitochondrial genomes. Recombination between the mitochondrial genomes of IR58024A and MTC-5A around the atp6 gene was detected by Southern-blot analysis of cybrid plants. Such recombinant mitochondrial molecules were also cloned from IR58024A/Nipponbare cybrid callus. PCR analysis around the atp6 gene demonstrated that inter-parental recombination occurs in practically all cybrid calli within 2 weeks after protoplast fusion. At this point, parental and recombinant mitochondrial genomes coexisted within the callus. Over the course of further cultivation, however, mitochondrial genome diversity decreased as parental and/or recombinant genomes segregated out.     

A microsatellite-based,physically anchored linkage map for the gray,short-tailed Opossum (<Emphasis Type="Italic">Monodelphis domestica</Emphasis>)

The genome of the gray, short-tailed opossum, Monodelphis domestica, will be the first of any marsupial to be fully sequenced. The utility of this sequence will be greatly enhanced by construction and integration of detailed genetic and physical maps. Therefore, it is important to verify the unusual recombinational characteristics that were suggested by the ‘first-generation’ M. domestica linkage map; specifically, very low levels of recombination and severely reduced female recombination, both of which are contrary to patterns in other vertebrates. We constructed a new linkage map based on a different genetic cross, using a new and much larger set of map markers, and physically anchored and oriented the linkage groups onto chromosomes via fluorescence in-situ hybridization mapping. This map includes 150 loci in eight autosomal linkage groups corresponding to the eight autosome pairs, and spans 86–89% of the autosomal genome. The sex-averaged autosomal map covers 715 cM, with a full-length estimate of 866 cM; the shortest full-length linkage map reported for any vertebrate. The sex-specific maps confirmed severely reduced female recombination in all linkage groups, and an overall F/M map ratio =  0.54. These results greatly extend earlier findings, and provide an improved microsatellite-based linkage map for this species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The <Emphasis Type="Italic">rpl5</Emphasis>–<Emphasis Type="Italic">rps14</Emphasis> mitochondrial region: a hot spot for DNA rearrangements in <Emphasis Type="Italic">Solanum</Emphasis> spp. somatic hybrids

Southern analysis with rpl5 and rps14 mtDNA gene probes of Solanum tuberosum, S. commersonii and a sample of somatic hybrids detected polymorphisms between parents and the appearance of a novel restriction fragment in various hybrids. In one of them, detailed mtDNA analyses revealed various configurations of the rpl5–rps14 region present at different stoichiometries. Multiple inter-parental recombination events across homologous sequences were assumed to have caused these rearrangements. Sequence similarity searches detected one sequence putatively involved in the recombination upstream of the rpl5 gene. The presence of a second recombinogenic sequence was inferred. We propose two models to explain the mechanism responsible for obtaining the different rpl5–rps14 arrangements shown after somatic hybridization. Variability in the rpl5–rps14 region observed in both the parental species and their somatic hybrids suggests this region is a hot spot for mtDNA rearrangements in Solanum spp.Contribution no. 39 from the Institute of Plant Genetics, Research Division of Portici.Communicated by A. Brennicke