Showing papers on "Chromosome 22 published in 1971"
TL;DR: It has recently become possible to locate the major portion of the Y chromosomes in interphase nuclei1, and this technique is used to demonstrate that the Y chromosome is spatially associated with the nucleolus.
Abstract: INDIVIDUAL human chromosomes cannot be seen during interphase, and little is known of their intra-nuclear position during most of the cell cycle. The principal exception to this has been the X chromosomes: when there is more than one, they condense during interphase to form the sex chromatin, which is often located on the nuclear membrane. It has recently become possible to locate the major portion of the Y chromosome in interphase nuclei1, and we have used this technique to demonstrate that the Y chromosome is spatially associated with the nucleolus.
47 citations
TL;DR: It is suggested that most of the heterochromatin disclosed by the DNA d-r method is formed by repetitious DNA; and that the Y chromosome and perhaps some autosome regions in guinea pigs are formed by a type of heterochromeatin with properties different from those of the constitutive and facultative heterochROMatin.
Abstract: The chromosome complement and patterns of heterochromatin distribution (as demonstrated by the DNA d-r method) were studied from three different guinea pigs. Karyotype analyses showed that one of the females had a heteromorphic sex pair formed by a submetacentric X chromosome and a subterminal X chromosome originated by a shortening of the short arm (x-chromosome). The heterochromatin was mainly found in the pericentromeric areas of the autosomes and X chromosomes and in the short arm of pair 7. The Y chromosome exhibited a degree of heterochromatinization different from that of pericentromeric areas.—The analysis of the heterochromatin distribution in the X chromosomes showed that the smaller size of the heteromorphic x-chromosoine was probably due to a lack of heterochromatin in its short arm. Moreover, two out of the three animals studied had a heteromorphic pattern of heterochromatinization in the pair 21 characterized by heterochromatinization of the pericentromeric area in one chromosome and almost complete heterochromatinization of the other homologue.—It is suggested that most of the heterochromatin disclosed by the DNA d-r method is formed by repetitious DNA; and that the Y chromosome and perhaps some autosome regions in guinea pigs are formed by a type of heterochromatin with properties different from those of the constitutive and facultative heterochromatin (intermediate heterochromatin).
34 citations
TL;DR: It was shown by linkage tests and by cytogenetic studies that one arm of this metacentric chromosome corresponds to the M. musculus acrocentric chromosome carrying linkage group IX, in which the H-2 complex is found.
Abstract: Mus poschiavinus × M. musculus hybrids, which had seven metacentric chromosomes derived from the poschiavinus complement, were repeatedly backcrossed to M. musculus and selected for the chromosome carrying the H-2 complex. A line called T1/Klj was established which had one metacentric chromosome. It was shown by linkage tests and by cytogenetic studies that one arm of this metacentric chromosome corresponds to the M. musculus acrocentric chromosome carrying linkage group IX, in which the H-2 complex is found. The distance from the H-2 locus to the centromere was tentatively estimated as 14 map units.
29 citations
TL;DR: The human Y chromosome is not a “late-replicating” chromosome but terminates replication earlier than most of the autosomes, and the Y chromosome cannot be distinguished from the G chromosomes on the basis of a consistent and differential labeling pattern.
Abstract: An autoradiographic analysis (using continuous labeling with tritiated thymidine) was made on 317 cells from four normal males. The labeling pattern of the Y chromosome was compared to the first and the last chromosomes to complete replication as well as to G21–22. The Y chromosome was never found to be the last chromosome in the cell to complete replication. Instead, it completed DNA synthesis relatively early (usually among the first 10 chromosomes) but had a distinctively heavy label during the earliest stages of late-S. In 51% of those cells with one labeled G+Y chromosome, a G21–22 was labeled and the Y was not.—It was concluded, therefore, that the human Y chromosome is not a “late-replicating” chromosome but terminates replication earlier than most of the autosomes. In addition, the Y chromosome cannot be distinguished from the G chromosomes on the basis of a consistent and differential labeling pattern.
14 citations
TL;DR: The mitotic chromosomes in primary embryonic cultured cells of eight translocation stocks of Mus musculus were identified by their distinctive fluorescent banding patterns after staining with quinacrine mustard by correlation of cytologic and genetic information.
Abstract: The mitotic chromosomes in primary embryonic cultured cells of eight translocation stocks of Mus musculus were identified by their distinctive fluorescent banding patterns after staining with quinacrine mustard. By correlation of cytologic and genetic information, linkage group (LG) X was assigned to chromosome 7 and LG VIII to chromosome 5. Several earlier assignments were confirmed: LG I to chromosome 8, LG V to chromosome 2, LG XII to chromosome 19, LG XIII to chromosome 1, and LG XVIII to chromosome 9. In addition, chromosomes 4, 17, and 18 were identified in translocations, but the available genetic data did not permit linkage-group assignments. The centromere of chromosome 8 was located at the nv (Nijmegen waltzer) end of LG I by the two-breakpoint method. The position of the centromere of chromosome 1 at the fz (fuzzy) end of LG XIII and that of chromosome 9 at the nr (nervous) end of LG XVIII were confirmed by the same method.
13 citations
9 citations
TL;DR: This work has employed a method of differential staining of chromosomes based on the localization of repetitive DNA associated with heterochromatin in an attempt to characterize the role of “ghost” DNA in the assembly of chromosomes.
Abstract: Arrighi and Hsu (1971) have described a method of differential staining of chromosomes based on the localization of repetitive DNA associated with heterochromatin. We have employed this method in an a
8 citations
TL;DR: Another variant of the fluorescence pattern in a large Y chromosome with a terminal non-fluorescent segment of the long arms is found.
Abstract: WILSON et al.1 and Morillo-Cucci and German2 have reported on large Y chromosomes with a terminal non-fluorescent segment of the long arms. We have found another variant of the fluorescence pattern in a large Y.
6 citations
TL;DR: Chromosome aberrations were observed in the tapetum and pollen-mother-cells, generally in form of chromosome bridges, fragments and elimination of univalent chromosomes and fragments, probably responsible for failure of pairing among pairable chromosomes.
Abstract: Chromosome aberrations were observed in the tapetum and pollen-mother-cells, generally in form of chromosome bridges, fragments and elimination of univalent chromosomes and fragments. Chromatid bridge formation varied from 13.1 to 10.25% in the first and second anaphases respectively.
6 citations
TL;DR: It is found that the submetacentric chromosome which is present has the characteristic quinacrine-fluorescence pattern of a human chromosome 17, presumably carrying the human thymidine kinase locus.
Abstract: Top of pageAbstract
Human chromosomes are preferentially eliminatd from man/mouse somatic hybrid cells. Two groups of works obtained viable hybrids by mixing human cells with a murine cell line lacking thymidine kinase and growing the mixture of cells in a selective medium in which cell survival required the presence of this enzyme. The hybrid cells usually contained a single human submetacentric chromosome, whose size and shape suggested that it was a memeber of the E-group, either chromosome 17 or 18. This chromosome presumably carries the human thymidine kinase locus.
Chromosomes of the E-group can be readily identified in human cells by their distinctive quinacrine-fluorescence patterns. By applying this technique to metaphase figures from one of the hybrid cell lines studied by Migeon and Miller (Science 162, 1005, 1968), we have found that the submetacentric chromosome which is present has the characteristic quinacrine-fluorescence pattern of a human chromosome 17.
TL;DR: Autoradiographic terminal labeling studies performed on leukocyte cultures of a man and his son demonstrated that the morphological marker was a No. 15, and possible interpretations of these findings, i.e., chromosomal polymorphism or autosomal lyonization, were discussed.
Abstract: Autoradiographic terminal labeling studies performed on leukocyte cultures of a man (A. de J.) and his son (H. de J.), both carriers of an enlarged satellite on a D-group chromosome, demonstrated that the morphological marker was a No. 15. Counts of grains on the long arms of the two chromosomes 15 showed that the marker chromosome was less heavily labeled than its normal homolog. This difference was highly significant in both cases. The marker chromosome was also shorter than its homolog, though not significantly so in one case. Possible interpretations of these findings, i.e., chromosomal polymorphism or autosomal lyonization, were discussed.
TL;DR: The results support the hypothesis that the observed effects of autosomal translocation homozygosity on recombination in the X chromosome are due to Homozygosity for position effects of the translocation breakpoints and are not due to chromosome discontinuity.
Abstract: X chromosome recombination was measured in females carrying two 2; 3-translocations. Total X chromosome recombination values varied according to the amount of structural heterozygosity between the two translocations. The results support the hypothesis that the observed effects of autosomal translocation homozygosity on recombination in the X chromosome are due to homozygosity for position effects of the translocation breakpoints and are not due to chromosome discontinuity.