摘要:

In the embryonic mouse ovary, studies of meiotic onset reveal the existence of a preleptotene stage of chromosome condensation. This stage begins with the appearance of very fine and irregular filaments, which gather around the chromocenters constituted by centromeric heterochromatin. At maximal condensation the nucleus contains 40 compact chromosomal masses. Decondensation engenders the reappearance of filaments more dense and regular than those seen at the onset of the condensation stage. The filaments elongate while progressively taking on the appearance of leptotene-stage chromosomes. The oocytes at different phases of condensation stage represent 41 % of the germ cells in the 13-day-old mouse embryo. This proportion reaches 63 % at 14 days and then declines to 3 % at 17 days. Spectrophotometric studies of the condensation-stage nucleus, following staining by the Feulgen reaction, indicate that the nucleus contains 4C DNA. This observation, together with the morphologic characteristics of this stage, suggests that the oocyte is already engaged in prophase. Time studies indicate that the condensation stage occurs immediately prior to leptotene.

ISSN:1424-8581    

DOI:10.1159/000130777

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

A formula is proposed for estimating statistically the degree of somatic chromosome association during metaphase. Standard chi-square tests can then be used to determine the presence or absence of somatic association between homologous chromosomes in selected species. The method requires that the chromosomes be morphologically distinguishable and that their circular arrangement on the metaphase plate has not been distorted by the squash used during their preparation.

ISSN:1424-8581    

DOI:10.1159/000130778

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Somatic cell hybrids between mouse cells and human cells carrying a reciprocal translocation between chromosomes 1 and 7 were tested for the expression of human enolase 1 (ENO1) by starch-gel electrophoresis. The results indicated that the gene for human enolase 1 can be assigned to the region p36→pter of human chromosome

ISSN:1424-8581    

DOI:10.1159/000130779

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

Three X/autosomal translocations, two familial and one de novo, were analyzed. Late-replicating chromosomes and chromosome regions were studied with R-banding techniques after BrdU incorporation. The first translocation, t(X;4)(q21;ql3), was a de novo translocation, found in a woman with amenorrhea. The structurally normal X was late replicating in all cells. The second translocation, t(X;6)(p21;q26), was found in an unbalanced form, 46, XX, der(6), in a phenotypically abnormal girl; her mother carried the balanced translocation. In the mother’s blood culture inactivation of the X’s followed two modes: In 85 % of the cells the normal X was late replicating, and in the remaining 15 % the der(X) was inactivated, including the attached fragment of chromosome 6. The third translocation, t(X;17)(pll;q24), was found in three generations. In the phenotypically normal mother, who carried the balanced translocation, the late-replicating X was always the normal X. In her daughters, who had an unbalanced karyotype, 46, X, der(X), and multiple congenital abnormalities, the X part of the translocation chromosome was always late replicating. No spreading of inactivation over the attached autosomal region was observed, resulting for these patients in a partial trisomy of 17q. Their peculiar phenotype is descri

ISSN:1424-8581    

DOI:10.1159/000130780

出版商:S. Karger AG    

年代:1977

数据来源: Karger

摘要:

A comparison of the sequence of terminal replication of DNA in human chromosomes has been made between skin fibroblasts and peripheral blood lymphocytes from the same adult male individual. The chromosomes were identified by quinacrine-banding, and the order of termination of replication was determined by autoradiography. Chromosomes 4, 5, 8, and 13 were found to terminate DNA replication later in lymphocytes than in fibroblasts, whereas chromosomes 15, 19, 20, and 22 were found to terminate their replication earlier in lymphocytes than in fibroblasts.

ISSN:1424-8581    

DOI:10.1159/000130781

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130782

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130783

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130784

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130785

出版商:S. Karger AG    

年代:1977

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130786

出版商:S. Karger AG    

年代:1977

数据来源: Karger