Chromosome

About: Chromosome is a research topic. Over the lifetime, 17538 publications have been published within this topic receiving 660077 citations. The topic is also known as: chromosomes & GO:0005694.

The Ph1 locus is needed to ensure specific somatic and meiotic centromere association.

Abstract: The correct pairing and segregation of chromosomes during meiosis is essential for genetic stability and subsequent fertility. This is more difficult to achieve in polyploid species, such as wheat, because they possess more than one diploid set of similar chromosomes. In wheat, the Ph1 locus ensures correct homologue pairing and recombination. Although clustering of telomeres into a bouquet early in meiosis has been suggested to facilitate homologue pairing, centromeres associate in pairs in polyploid cereals early during floral development. We can now extend this observation to root development. Here we show that the Ph1 locus acts both meiotically and somatically by reducing non-homologous centromere associations. This has the effect of promoting true homologous association when centromeres are induced to associate. In fact, non-homologously associated centromeres separate at the beginning of meiosis in the presence, but not the absence, of Ph1. This permits the correction of homologue association during the telomere-bouquet stage in meiosis. We conclude that the Ph1 locus is not responsible for the induction of centromere association, but rather for its specificity.

Chromosome abnormalities in human arrested preimplantation embryos : a multiple-probe FISH study

Abstract: Numerical chromosome abnormalities were studied in single blastomeres from arrested or otherwise morphologically abnormal human preimplantation embryos A 6-h FISH procedure with fluorochrome-labeled DNA probes was developed to determine numerical abnormalities of chromosomes X, Y, and 18 The three chromosomes were stained and detected simultaneously in 571 blastomeres from 131 embryos Successful analysis including biopsy, fixation, and FISH analysis was achieved in 865% of all blastomeres The procedure described here offers a reliable alternative to sexing of embryos by PCR and allows simultaneous ploidy assessment For the three chromosomes tested, numerical aberrations were found in 565% of the embryos Most abnormal embryos were polyploid or mosaics, and 61% were aneuploid for gonosomes or chromosome 18 Extrapolation of these results to all human chromosomes suggests that the majority of abnormally developing and arrested human embryos carry numerical chromosome abnormalities

Formation of new chromosomes as a virulence mechanism in yeast Candida glabrata

Abstract: In eukaryotes, the number and rough organization of chromosomes is well preserved within isolates of the same species. Novel chromosomes and loss of chromosomes are infrequent and usually associated with pathological events. Here, we analyzed 40 pathogenic isolates of a haploid and asexual yeast, Candida glabrata, for their genome structure and stability. This organism has recently become the second most prevalent yeast pathogen in humans. Although the gene sequences were well conserved among different strains, their chromosome structures differed drastically. The most frequent events reshaping chromosomes were translocations of chromosomal arms. However, also larger segmental duplications were frequent and occasionally we observed novel chromosomes. Apparently, this yeast can generate a new chromosome by duplication of chromosome segments carrying a centromere and subsequently adding novel telomeric ends. We show that the observed genome plasticity is connected with antifungal drug resistance and it is likely an advantage in the human body, where environmental conditions fluctuate a lot.

A gapless genome sequence of the fungus Botrytis cinerea

Abstract: Following earlier incomplete and fragmented versions of a genome sequence for the grey mould Botrytis cinerea, a gapless, near-finished genome sequence for B. cinerea strain B05.10 is reported. The assembly comprised 18 chromosomes and was confirmed by an optical map and a genetic map based on approximately 75 000 single nucleotide polymorphism (SNP) markers. All chromosomes contained fully assembled centromeric regions, and 10 chromosomes had telomeres on both ends. The genetic map consisted of 4153 cM and a comparison of the genetic distances with the physical distances identified 40 recombination hotspots. The linkage map also identified two mutations, located in the previously described genes Bos1 and BcsdhB, that conferred resistance to the fungicides boscalid and iprodione. The genome was predicted to encode 11 701 proteins. RNAseq data from >20 different samples were used to validate and improve gene models. Manual curation of chromosome 1 revealed interesting features, such as the occurrence of a dicistronic transcript and fully overlapping genes in opposite orientations, as well as many spliced antisense transcripts. Manual curation also revealed that the untranslated regions (UTRs) of genes can be complex and long, with many UTRs exceeding lengths of 1 kb and possessing multiple introns. Community annotation is in progress.

Chromosomal location of genes controlling seed proteins in species related to wheat.

Abstract: The seed proteins of ‘Chinese Spring’ wheat stocks which possess single chromosomes from other plant species related to wheat have been separated by gel electrophoresis in the presence of sodium dodecyl sulphate. Marker protein bands have been detected for both arms of barley chromosome 5, chromosome E (= 1R) and B (= 2R) of rye, chromosomes A,B (= 1Cu) and C (= 5Cu) of Aegilops umbellulata and chromosomes I and III of Agropyron elongatum. These studies, and previous findings, indicate that chromosome 5 of barley, chromosome 1R of rye, chromosome I of Ag. elongatum and possibly chromosome 1Cu of Ae. umbellulata are similar to chromosomes 1A, 1B and 1D in hexaploid wheat in that they carry genes controlling prolamins on their short arms and genes controlling high-molecular-weight (apparent molecular weight greater than 86,000) seed protein species on their long arms. These findings support the idea that all these chromosomes are derived from a common ancestral chromosome and that they have maintained their integrity since their derivation from that ancestral chromosome.