ISSN:1424-8581    

DOI:10.1159/000130900

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Variations in lateral asymmetry of human chromosome 1 were studied in 17 amniotic cell samples and eight blood samples by the 5-bromodeoxyuridine (BrdU) quenching of 4’-6-diamidino-2-phenylindole (DAPI) fluorescence. The size and the relative proportion of the bright fluorescent spots on each chromatid in the heterochromatic region of chromosome 1 (1qh) are variable from different amniotic (or blood) samples after one cycle of BrdU incorporation. However, the particular pattern for a given chromosome 1 is consistent within the individual sample. Size variations were classified into three groups, and variations in the pattern (proportion) of bright fluorescence on each chromatid in the lqh region were classified into four groups. A preliminary estimate of the type and frequency of lateral asymmetry variations was obtained. These results suggest a high frequency of variability of heterochromatin in the population. The BrdU-DAPI fluorescence technique was found to be very useful for characterizing variations in the lqh region; variations in organization of heterochromatin DNA within the lqh region can be detected, and a simple system of nomenclature is proposed for naming the variations in this regio

ISSN:1424-8581    

DOI:10.1159/000130901

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

An automated system providing quantitative measurements of C-band size has been used, in conjunction with statistical methodology developed for the purpose, in a family study to demonstrate its potential in determining the mode of transmission of C-bands from parent to offspring, and to test the assumption of Mendelian inheritance. The most serious obstacle encountered was the high within-person variance of the normalized band sizes, the large within-slide variance being increased by technical variation between different preparations. Attempts to reduce variance by developing more effective normalization techniques did not prove fruitful. Nevertheless, the ability of the present system to perform a trace using a reasonable number of cells has been demonstrated in an example. In the two families studied we saw no evidence that band size was not transmitted and changes in band size, if any, were less than about 5 µm2 × 10–2 (compared to a typical medium-category band size of about 65 µm2 x 10–2<

ISSN:1424-8581    

DOI:10.1159/000130902

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The chromosomes in spermatogenic cells of 10 cockerels were examined. Prior to removing the testes, the birds had been injected with either 2.5 mg vinblastine sulfate or 5 mg colchicine, or were untreated. A cell suspension was made from small pieces of testis and slides were prepared using an air-drying technique. Pretreatments of the birds increased the numbers of spermatogonial and secondary spermatocyte cells at metaphase and rendered them more amenable to analysis. The modal number of macrochromosomes or bivalents was observed in 90.2 % of spermatogonia, 98 % of primary spermatocytes at diakinesis, and 94.2 % of secondary spermatocytes. Polyploid cells at all stages were thought to be largely artifacts of the procedure. Aneuploidy was rare, being found in only 1 % of secondary spermatocytes. It is estimated that between 56 and 66 chiasmata occur in the 39 bivalents; of these, an average of 28 are seen in the six macrobivalents. Average numbers were 8.1, 5.9, 4.6, 3.6, 2.4, and 3.5 for macrobivalents 1 through 5 and the Z respectively. The numbers of chiasmata differed significantly among birds but were not differentially affected by pretreatment of the birds.

ISSN:1424-8581    

DOI:10.1159/000130903

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Two recent technical advances facilitate the derivation of proliferating hybrids from human diploid fibroblast strains without recourse to biochemical selection: (1) a new chemically-mediated method of somatic cell fusion (PEG-DMSO) yields hybrids at rates as high as 1 in 160 colonies after dilute plating of treated cell mixtures, and (2) a simple technology for assessment of DNA content (flow microfluorometry) permits rapid and highly sensitive monitoring of ploidy. Employing these techniques, we isolated 43 chromosomally stable hybrid clones from 12 crosses between seven different strains representing a wide range of longevities. Crosses between short-lived strains resulted in short-lived hybrid offspring, whereas hybrids derived from long-lived parents tended to be long-lived. Crosses between strains of contrasting longevities gave clones with intermediate growth potentials relative to the other types of hybrids. The failure to observe complementation (enhanced longevity) of hybrids argues against random recessive single-copy gene mutations as important determinants of clonal senescence.

ISSN:1424-8581    

DOI:10.1159/000130904

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130905

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130906

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130907

出版商:S. Karger AG    

年代:1978

数据来源: Karger