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.

Molecular and chromosomal organization of DNA sequences coding for the ribosomal RNAs in cereals

Abstract: The chromosomal locations of ribosomal DNA in wheat, rye and barley have been determined by in situ hybridization using high specific activity 125I-rRNA. The 18S-5.8S-26S rRNA gene repeat units in hexaploid wheat (cv. Chinese Spring) are on chromosomes 1B, 6B and 5D. In rye (cv. Imperial) the repeat units occur at a single site on chromosome 1R(E), while in barley (cv. Clipper) they are on both the chromosomes (6 and 7) which show secondary constrictions. In wheat and rye the major 5S RNA gene sites are close to the cytological secondary constrictions where the 18S-5.8S-26S repeating units are found, but in barley the site is on a chromosome not carrying the other rDNA sequences. — Restriction enzyme and R-loop analyses showed the 18S-5.8S-26S repeating units to be approximately 9.5 kb long in wheat, 9.0 kb in rye and barley to have two repeat lengths of 9.5 kb and 10 kb. Electron microscopic and restriction enzyme data suggest that the two barley forms may not be interpersed. Digestion with EcoR1 gave similar patterns in the three species, with a single site in the 26S gene. Bam H1 digestion detected heterogeneity in the spacer regions of the two different repeats in barley, while in rye and wheat heterogeneity was shown within the 26S coding sequence by an absence of an effective Bam H1 site in some repeat units. EcoR1 and Bam H1 restriction sites have been mapped in each species. — The repeat unit of the 5S RNA genes was approximately 0.5 kb in wheat and rye and heterogeneity was evident. The analysis of the 5S RNA genes emphasizes the homoeology between chromosomes 1B of wheat and 1R of rye since both have these genes in the same position relative to the secondary constriction. In barley we did not find a dominant monomer repeat unit for the 5S genes.

Gene for alpha-chain of human T-cell receptor: location on chromosome 14 region involved in T-cell neoplasms

Abstract: A human complementary DNA clone specific for the alpha-chain of the T-cell receptor and a panel of rodent X human somatic cell hybrids were used to map the alpha-chain gene to human chromosome 14 in a region proximal to the immunoglobulin heavy chain locus. Analysis by means of in situ hybridization of human metaphase chromosomes served to further localize the alpha-chain gene to region 14q11q12, which is consistently involved in translocations and inversions detectable in human T-cell leukemias and lymphomas. Thus, the locus for the alpha-chain T-cell receptor may participate in oncogene activation in T-cell tumors.

Mechanisms of chromosome banding and implications for chromosome structure.

Abstract: INTRODUCTION 25 HlSTONES AND CHROMOSOME BANDING .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 C-BANDING-EXTRACTION OF NON-C-BAND DNA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 G-BANDS=CHROMOMERES OF MEIOTIC CHROMOSOMES 29 MAJOR G-BANDS ARE COMPOSED OF SEVERAL SMALLER CHROMOMERES .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 GIEMSA STAINING-SIDE STACKING OF THIAZIN DYES ON DNA ..... . . . 30 G-BANDING-ENHANCEMENT OF THE CHROMOMERE PATTERN ... . . . . . 3 1 Q-BANDING-DETECTION OF AT-RICH DNA .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 HOECHST 33258 BANDING-DETECTION OF AT-RICH DNA ... . . . . . . . . . . . . . . . . . . . 35 R-BANDING DETECTION OF GC-RICH DNA 35 Qor R-BANDING BASED ON EARLY REPLICATING DNA IN R-BANDS AND LATE REPLICATING DNA IN Qor G-BANDS . . . . . . . . . . . . . . . . . . . . . . 37 CHROMOSOME BANDS DELINEATE THREE TYPES OF CHROMATIN .... 38 IMPLICATION OF CHROMOSOME BANDING FOR CHROMOSOME STRUCTURE 39

Advanced-stage cervical carcinomas are defined by a recurrent pattern of chromosomal aberrations revealing high genetic instability and a consistent gain of chromosome arm 3q

Abstract: We have analyzed 30 cases of advanced-stage cervical squamous cell carcinoma (stages IIb–IV) by comparative genomic hybridization (CGH). The most consistent chromosomal gain in the aneuploid tumors was mapped to chromosome arm 3q in 77% of the cases. Acquisition of genetic material also occurred frequently on 1q (47%), 5p (30%), 6p (27%), and 20 (23%). Recurrent losses were mapped on 2q (33%), 3p (50%), 4 (33%), 8p (23%), and 13q (27%). High-level copy number increases were mapped to chromosome 8, chromosome arms 3q, 5p, 8q, 12p, 14q, 17q, 19q, 20p, and 20q, and chromosomal bands 3q26-27, 9p23-24, 11q22-23, and 12p13. In the majority of the cases, the presence of high-risk human papilloma virus genomes was detected. High proliferative activity was accompanied by crude aneuploidy. Increased p21/WAF-1 activity, but low or undetectable expression of TP53 were representative for the immunophenotype. This study confirms the importance of a gain of chromosome arm 3q in cervical carcinogenesis and identifies additional, recurrent chromosomal aberrations that are required for progression from stage I tumors to advanced-stage carcinomas. Genes Chromosom. Cancer 19:233–240, 1997. Published 1997 Wiley-Liss, Inc.

Analysis of the Size Distributions of Fetal and Maternal Cell-Free DNA by Paired-End Sequencing

Abstract: BACKGROUND: Noninvasive prenatal diagnosis with cell-free DNA in maternal plasma is challenging because only a small portion of the DNA sample is derived from the fetus. A few previous studies provided size-range estimates of maternal and fetal DNA, but direct measurement of the size distributions is difficult because of the small quantity of cell-free DNA. METHODS: We used high-throughput paired-end sequencing to directly measure the size distributions of maternal and fetal DNA in cell-free maternal plasma collected from 3 typical diploid and 4 aneuploid male pregnancies. As a control, restriction fragments of DNA were also sequenced. RESULTS: Cell-free DNA had a dominant peak at approximately162bpandaminorpeakatapproximately 340 bp. Chromosome Y sequences were rarely longer than 250 bp but were present in sizes of 150 bp at a larger proportion compared with the rest of the sequences. Selective analysis of the shortest fragments generally increased the fetal DNA fraction but did not necessarilyincreasethesensitivityofaneuploidydetection, owing to the reduction in the number of DNA molecules being counted. Restriction fragments of DNA with sizes between 60 bp and 120 bp were preferentially sequenced, indicating that the shotgun sequencing work flow introduced a bias toward shorter fragments. CONCLUSIONS: Our results confirm that fetal DNA is shorter than maternal DNA. The enrichment of fetal DNA by size selection, however, may not provide a dramatic increase in sensitivity for assays that rely on length measurement in situ because of a trade-off between the fetal DNA fraction and the number of molecules being counted. © 2010 American Association for Clinical Chemistry