Male sex chromosomal complement exacerbates the pathogenicity of Th17 cells in a chronic model of central nervous system autoimmunity

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Chromosomal behavior of anther culture derived plants of rice

Cytological examination of anther-culture-derived plants of rice showed that the regenerants were predominantly diploids and haploids. Haploid meiosis indicated that the earlier hypothesis of rice being an ancient polyploid is unlikely. Diploids generally were normal and fertile. The low frequency of polyploids (1.5%) probably was due to rapid regeneration of plants from short term callus cultures.     

Protective effect of cysteine against X-ray- and bleomycin-induced chromosomal aberrations and cell cycle delay

The protective effect of cysteine was studied in muntjac and human lymphocytes in vitro scoring chromosomal aberrations in harlequin stained first cycle metaphases, induced by X-irradiation at G₀. Its protective efficiency was also studied against the radiomimetic clastogen, bleomycin, in muntjac cells. 30 μg and 1 mg/ml of cysteine were given prior to 2, 3, and 4 Gy, and 2 mg/ml prior to only 4 Gy. 30 μg cysteine protected only against deletions in 4 Gy-treated cells while 1 mg protected against deletions by all three doses of X-rays. However, rearrangements were not reduced significantly in any of these, probably due to their low frequency. But when cysteine was increased to 2 mg, both types of aberrations were reduced significantly. This shows that a sufficient number of aberrations and an optimum concentration of the protector are essential for eliciting the best protective effect. This conclusion is further supported by the results of 2 mg cysteine treatment in human lymphocytes which yielded higher frequencies of rearrangements with 2 and 3 Gy X-rays than 4 Gy in muntjac, but had a relatively lower frequency of deletions. Thus the most abundant categories of aberration, i.e., deletions in muntjac and exchanges in humans, were reduced significantly by 2 mg cysteine, associated with a prominent reduction in the frequency of aberrant metaphases. Therefore, the differential protection observed with a low concentration of the protector and an insufficient yield of aberrations induced only indicates protection provided to the most frequent type of aberration by a protector when present in lower concentration.

Cysteine pretreatment yielded weak protection against the effects of bleomycin, but posttreatment caused a mild potentiation of the clastogenic effect of BLM without altering the cell cycle kinetics. In this context, an action of cysteine as a reducing agent on BLM is suggested. Although cysteine alone caused severe retardation of the cell cycle, when given prior to X-irradiation, not only its delaying effect was not observed, but also it reduced the X-ray induced cell cycle delay. This might be due to the oxidation of cysteine by its radical scavenging action.     

Characterizing meiotic chromosomes' structure and pairing using a designer sequence optimized for Hi‐C

In chromosome conformation capture experiments (Hi‐C), the accuracy with which contacts are detected varies due to the uneven distribution of restriction sites along genomes. In addition, repeated sequences or homologous regions remain indistinguishable because of the ambiguities they introduce during the alignment of the sequencing reads. We addressed both limitations by designing and engineering 144 kb of a yeast chromosome with regularly spaced restriction sites (Syn‐HiC design). In the Syn‐HiC region, Hi‐C signal‐to‐noise ratio is enhanced and can be used to measure the shape of an unbiased distribution of contact frequencies, allowing to propose a robust definition of a Hi‐C experiment resolution. The redesigned region is also distinguishable from its native homologous counterpart in an otherwise isogenic diploid strain. As a proof of principle, we tracked homologous chromosomes during meiotic prophase in synchronized and pachytene‐arrested cells and captured important features of their spatial reorganization, such as chromatin restructuration into arrays of Rec8‐delimited loops, centromere declustering, individualization, and pairing. Overall, we illustrate the promises held by redesigning genomic regions to explore complex biological questions.     

Mycorrhizal colonization in cowpea is host dependent and heritable

Cowpea genotypes (101) of diverse origin were evaluated for their endomycorrhizal colonization under natural field conditions in an alfisol soil. There was considerable variation in colonization ranging from 0 to 28.6%. The genetic coefficient of variability was high (55.9), heritability moderate (46.2) with high genetic advance (78.3) revealing that mycorrhizal colonization is not only host dependent but heritable.