Showing papers on "Chromosome 21 published in 1972"

Trisomy for the smallest autosome of the mouse and identification of the T1Wh translocation chromosome

Abstract: Quinacrine-mustard staining and Giemsa-banding identified the large chromosome of the T1Wh translocations as No. 5; the small autosome of the translocation had previously been found to be No. 19. Others have demonstrated that translocation T163H involved autosomes 9 and 19; these findings were confirmed in our study. Meiotic studies of (T1Wh × T163H) F1 hybrids showed a chain quadrivalent at metaphase I, confirming that both translocations shared in common only chromosome 19. Metaphase II analysis of F1 hybrids demonstrated frequent nondisjunction of the T1Wh and T163H translocation chromosomes, and 12 % of 75 F2 offspring from 16 F1 crosses were trisomic for chromosome 19. Trisomics had three translocation chromosomes and a chromosome number of 38. All newborn trisomics were smaller than their normal littermates and died during the first day of life. The only specific malformation found so far has been cleft palate.

The t6 translocation in the mouse: its use in trisomy mapping, centromere localization, and cytological identification of linkage group iii

Abstract: The occurrence of hairless piebald mice trisomic for the chromosome segments of the T6M chromosome has shown that the LG III loci hr and s are not located on T6M. The T6 breakpoint in LG III is therefore in the position hr—s—T6. T6M must carry the gene Fkl, which is located on the far side of the T6 breakpoint from hr in LG III.—T6 reduces recombination in the hr—s region.—Trisomy for the chromosome segments of the T6M chromosome appears to severely reduce viability.—The gene hr has been shown to lie between the centromere and the T6 breakpoint. The order of loci in LG III is therefore: centromere—hr—s—T6.—Equations are given for the relation between the frequency of adjacent-2 segregation and the frequency of recovery of complementation zygotes for the case in which the translocation heterozygote can form either quadrivalent or univalent–trivalent configurations at meiosis.—Linkage Group III is carried on chromosome 14. LG VI is the other linkage group involved in T6, and is carried on chromosome 15.

G6PD expression and X chromosome late replication in fibroblast clones from a female mule.

Abstract: THE relationship between late DNA replication and X chromosome inactivation is supported by strong circumstantial evidence1–3. The use of clones derived from a female mule1 typed for Gd and at the same passage labelled with 3H-TdR and subsequently autoradiographed should provide final proof of this relationship.

Cytological identification of the chromosomes involved in Searle's translocation and the location of the centromere in the X chromosome of the mouse.

Abstract: The autosome in Searle's X-autosome translocation has been shown to be chromosome 16. The breakpoint in chromosome 16 is slightly proximal to the middle and in the X is slightly distal to the middle.—Available evidence indicates that either Linkage Group XV or Linkage Group XIX is carried on chromosome 16.—The centromere of the X chromosome is at the spf end of the linkage group.

Allelic complementation between mutants in the fertility factors of the Y chromosome in Drosophila melanogaster

Abstract: Complementation maps of the seven male fertility factors in the Y chromosome of D. melanogaster have been constructed and are linearly consistent in all cases. These observations are further evidence that genetic loci in heterochromatic chromosomes share many characteristics with loci in euchromatic regions of chromosomes. These functional maps are consistent with the hypothesis that the genetic material of the male fertility factors in the Y chromosome is made up of single-copy sequences which become amplified in the primary spermatocyte.

A marker chromosome number 14 with double satellite observed in two generations: An unbalanced chromosome constitution associated with normal phenotype

Abstract: 2 phenotypically normal subjects, both carriers of a double satellite on the short arm of a D-group chromosome, have been studied. The marker chromosome has been identified as a number 14 by means of autoradiography. All D-and G-group chromosomes show satellites in both subjects. Two of the possible mechanisms of formation of a double satellite are described. The variability in the expression of satellites and the frequency of satellite association of the single D-group chromosomes have also been studied. It has to be stressed that these individuals, though being carriers of a partial trisomy, are both phenotypically normal.

Monosomy 21 in spontaneous abortus.

Abstract: Chromosome analysis of the amnion from a missed abortus revealed a 45,XX,G-karyotype. Giemsa banding pattern technique identified the chromosome involved in monosomy as No. 21.

Brachymesophalangia-5 without cone-epiphysis mid-5 in Down's syndrome

Abstract: Brachymesophalangia-5 proved to be far more frequent in 212 cases of Down's syndrome karyotype (ie, 21%) than in 14,197 survey volunteers of European ancestry (14%) However, none of 28 juvenile Down's syndrome patients with brachymesophalangia-5 exhibited a cone-epiphysis on mid-5, as against the 47% that would be expected Apparently the manifestation of brachymesophalangia-5 in the 47,G + karyotype is not simply a dosage effect associated with trisomy of chromosome 21

A Gq Deletion in a Girl with Down’s Syndrome

Abstract: A girl with some signs of Down’s syndrome and mild mental retardation is presented She had a deleted extra chromosome 21 in 907% of the leucocytes investigated and in 576% of the skin cells analysed The rest of the cells analysed had a karyotype of 47, XX,21 +

Chromosome 16: a specific chromosomal pathway for the origin of human malignancy?

Abstract: Minkler, Gofman and Tandy (1970a, b) have recently reported data on the karyotype constitutions of human tissue culture cell lines and human tumours, as gathered by a semi-automatic chromosome analysis system. The data appears to show a relationship between the relative number of “number 16” chromosomes and malignancy. We have tested the ability of the “cutting line” approach they used to correctly classify chromosomes from a sample of 723 cells from 100 normal subjects. The cutting line scheme gave very different results from those of an experienced cytogeneticist. The method also failed to give correct average numbers of chromosomes per class. We are thus led to question the conclusions reached by Minkler et al. It appears possible that their relatively consistent finding of an excess of “number 16” chromosomes in their largely hyperploid material may be an artefact of their classification scheme, arising from measurement normalization problems, rather than a reflection of a real excess of “number 16” or even of “number 16-like” chromosomes.

Replication pattern of the X and Y chromosomes in partially synchronized human lymphocyte cultures.

Abstract: The replication pattern of the X and Y chromosomes at the beginning of the synthetic phase was studied in human lymphocyte cultures partially synchronized by the addition of 5-fluoro-2′-deoxyuridine (FUdR). The data were evaluated statistically by an analysis of the distribution of silver grain counts over the X and Y chromosomes. —In cells from normal females, one of the X chromosomes began replication later than any other chromosomes of the complement. The short arm of the late replicating X chromosome started replication earlier than the long arm. The telomeric region of the short arm was a preferential site of DNA synthesis at the beginning of replication. —In partially synchronized lymphocyte cultures from a patient with the XXY syndrome, the Y chromosome started replication together with the late replicating X chromosome. The Y chromosome most frequently replicated synchronously with the short arm of the X. The centromeric region of the Y chromosome initiated synthesis before the telomeric region and appeared to replicate synchronously with the telomeric region of the short arm of the X. These findings are discussed with reference to the pairing of the X and Y chromosomes at meiosis.