摘要:

The chromosomes of the Indian rock python, Python molurus (sub-family Pythoninae), and the sand boa, Eryx johni johni (Boinae), were investigated and compared with those of Boa constrictor (Boinae). A striking similarity of the chromosomes of Boa and Python was observed, but the karyotype of the Eryx was found to be different from that of the other two species. This investigation clearly supports the validity of the doubt expressed by some taxonomists regarding a close phylogenetic relationship between Boa and Eryx.

ISSN:1424-8581    

DOI:10.1159/000129980

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

The karyotype analysis of a mentally retarded baby with persistence of embryonic and foetal haemoglobin showed three abnormal chromosomes. One was identified as a No. 3 with an extra segment, another as No. 6 or 7, or X, with a deletion and the last one was assigned to pair 15 by autoradiography. The parents of the propositus were both haematologically and chromosomally normal. The possible mechanisms of origin of the multiple chromosomal rearrangements arc discussed. The data are also compared with those reported by other authors in connection with different chromosomal abnormalities. Particular attention is paid to trisomy D, which has been found associated with persistence of foetal haemoglobin. Although the possibility of a nonspecific effect of the observed karyotypic alterations cannot be ruled out, the suggestion is made that one or more of the abnormal chromosomes are carriers of gene(s) controlling the synthesis of e and γ chains

ISSN:1424-8581    

DOI:10.1159/000129981

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Tissue cultures were established from Australian long-nosed bandicoot pouch young. Chromosome preparations from these cultures showed a karyotype with 12 autosomes and a XX/XY sex chromosome constitution. The six auto-some pairs are individually identifiable. The morphology of each pair is described, and further uses of this interesting karyotype are discussed.

ISSN:1424-8581    

DOI:10.1159/000129982

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Short-term human leukocyte cultures from two individuals with different cytological backgrounds were treated with 3H-thymidine. Gaps, deletions, fragments and translocations were observed. The two cases responded much differently probably owing to differences in genetic background. Using autoradiographic procedures, it was observed that aberrations arise more or less in equal frequency in the synthesizing regions of chromosomes as in regions which had completed DNA synthesis. Gaps are attributed to subchromatid breaks and are randomly located, i.e., not necessarily restricted to late-replicating, heterochromatic regions.

ISSN:1424-8581    

DOI:10.1159/000129983

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

The chromosomes of the reindeer (2n = 70) were studied with special reference to the chronology of DNA replication of the sex chromosomes. The X chromosome was metacentric and nearly of the duplicate type, being about 9% in length of the total complement. All the other chromosomes, including the Y, were acrocentric except one submetacentric pair. The X and Y chromosomes were apparently terminally associated at first meiotic metaphase in the male. A single, rather large chromocenter was observed in the majority of cultured female cells. The male cells were predominately negative but occasionally demonstrated a somewhat smaller, distinct chromocenter. Autoradiography showed that in the female cultured cells the ‘one entire X plus half of the other X heavily labelled’ pattern was conspicuously present at the end of the S period. A quantitative analysis indicated that one hour from the end of the S period both X chromosomes were uniformely labelled. One X was still completely labelled, while one arm of the other was not 45 min before the end of S, and at 30 min only one arm in each X chromosome was labelled. The two X chromosomes then seemed to be slightly asynchronous until the very end of S. In the male cells semiquantitative analysis indicated that one arm of the X and the entire Y chromosome were synchronous in terminating DNA synthe

ISSN:1424-8581    

DOI:10.1159/000129984

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Intrafollicular overripeness was studied in eggs of Xenopus which had been prevented from ovulating for extended periods. When ovulation was artificially induced, a number of eggs at various degrees were released. High mortality and malformation rates were recorded. Range and types of abnormalities were much like those in other amphibians developed from eggs affected by intrauterine overripeness. This suggests that the pathological change of the ovarian eggs is very similar to that of the uterine eggs. Effects on the meiotic spindle were studied in 353 externally normal eggs that were collected from various portions of the reproductive tract. In 179 eggs which were sectioned to show the maturation spindle in side view, 3 cases in first meiotic metaphase and 20 in second metaphase exhibited abnormal chromosomal behavior. This included precocious movement of one or two undivided tetrads and dyads to the outer or the inner spindle poles and loss of polarization of the displaced chromosomes. It was suggested that these might be caused by disintegration of the spindle fibers and related to the nondisjunction of the meiotic chromosomes. In obviously degenerating uterine eggs, disintegration of the spindle fibers was evidenced by the loss of connection of spindle fibers with the central body. Degeneration of chromosomes and hypertrophy of the spindle were also characteristic in these eggs. The importance of intrafollicular overripeness of ovocytes in the etiology of human spontaneous abortion and of congenital malformation is discussed.

ISSN:1424-8581    

DOI:10.1159/000129985

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Techniques are now available for the study of meiosis in the human female through the short term culture of oocytes from ovaries. One cell, in which 23 bivalents could be distinguished, shows interstitial chiasmata in the bivalents, in which all four strands can be distinguished. The small bivalents appear to terminalise first. The chiasma count was consistent with the number in the male.

ISSN:1424-8581    

DOI:10.1159/000129986

出版商:S. Karger AG    

年代:1968

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129987

出版商:S. Karger AG    

年代:1968

数据来源: Karger