摘要:

An analysis of the meiotic chromosomes of Cebus apella (Cebidae, Platyrrhini) has allowed for the visualization of constitutive heterochromatic regions throughout the meiotic cycle and has permitted the identification of four chromosomes in the first and the second divisions. In pachytene nuclei, and in pachytene spreads where synaptonemal complexes were visible, one heterochromatic region was frequently unpaired. No chiasmata were found in heterochromatic regions, and there was no evidence of chiasma terminalization. The role of heterochromatin in homologous pairing and its relationship to chiasma position and number in meiotic configurations were discussed. A comparison was made between bivalent 9 in C. apella and bivalent 21 in man, based on the interspecific homologies between these chromosomes. A similar comparison was made between the Algerian and Asian hedgehogs, where marked differences in the content of constitutive heterochromatin occur in two chromosome pairs.

ISSN:1424-8581    

DOI:10.1159/000131966

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

A monoclonal antiserum, 66-IG10, raised against human thymocytes was found to be directed against the human transferrin receptor. A panel of human x Chinese hamster somatic cell hybrids, in conjunction with the 66TG10 reagent, was used to assign the gene(s) coding for the transferrin receptor to the ql2→qter region of human chromosome

ISSN:1424-8581    

DOI:10.1159/000131967

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

The relationship between cell kinetics and cell harvest time on sister chromatid exchange (SCE) and NOR (marker chromosome) association was investigated in cultured Macaca fuscata lymphocytes. The average number of SCE’s in individuals ranged from 3.77 to 9.07 per cell. The highest SCE rate was founc in cultures harvested at 60 h. The data suggest a decrease in SCE frequency between 60 h and subsequent cell harvest at 72, 84, and 96 h. NOR association frequency was also affected by cell kinetics, as well as by eel harvest time. The highest association frequencies were at 48 h, when the number of first mitoses was greate

ISSN:1424-8581    

DOI:10.1159/000131968

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

To assess whether displacement—the appearance of individual chromosomes inside of the ring of chromosomes attached to spindle fibers—is a valid method of analyzing chromosome misdivision, displacement data from six healthy female subjects were compared with data for mitotic and meiotic nondisjunction. Statistical analysis indicated that nondisjunction and displacement are equivalent methods of assessing differential chromosome error. Tests for homogeneity of the data sets showed no significant heterogeneity for the mitotic data, but chromosomes 1, 2, 11, 16, 17, 19, and 20 were responsible for significant heterogeneity in the meiotic d

ISSN:1424-8581    

DOI:10.1159/000131969

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

A chromosomal banding study was carried out on Propithecus verreauxi verreauxi, P. verreauxi deckeni, and Avahi laniger laniger. Comparison of their karyotypes with those of Microcebus murinus and Lemur fulvus led to reconstruction of the ancestral Lemuriform karyotype and a determination that the branch leading to the Indridae was isolated very early, before the separation of the Lemuridae from the Cheirogaleidae. The karyotype of Avahi remained highly ancestral, whereas that of P. verreauxi was considerably modified, chiefly by Robersonian translocations.

ISSN:1424-8581    

DOI:10.1159/000131970

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Two different reciprocal translocations between chromosomes 1 and 13 in the mouse, T(1;13)70H and T(l;13)lWa, were intercrossed, resulting in T(l;13)70H/T(l;13)lWa animals, possessing two heteromorphic marker bivalents. The meiotic behavior of these animals was compared to that of T(1;13)70H/T(1;13)70H animals. In females the chiasma frequency in the translocation bivalents was decreased by the presence of the loops following meiotic pairing, but in males chiasma frequencies were not changed. The nondisjunction level of both translocation bivalents was increased in females and males. The nondisjunction level of bivalents not involved in the translocations was increased in the females, but not in the males. Possible causes and relevance of these phenomena are discussed.

ISSN:1424-8581    

DOI:10.1159/000131971

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Human lymphocyte cultures were treated with different concentrations of 5-azacytidine for various lengths of time. This cytosine analog induces very distinct undercondensation in the heterochromatin of chromosomes 1,9, 15, 16, and Y if applied in low doses during the last hours of culture. These regions are further distinguished by their intense distamycin A/DAPI-staining and highly methylated DNA. In interphase nuclei, these heterochromatic regions are frequently somatically paired. These somatic pairings are preserved up to the metaphase stage in the 5-azacytidine-treated cultures and are thus susceptible to direct analysis. The specific effect of 5-azacytidine on the heterochromatin of these chromosomes, its conserving effect on somatic pairing, and some of the consequences of the somatic pairing on the development of human chromosome aberrations are discussed.

ISSN:1424-8581    

DOI:10.1159/000131972

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Human metaphase chromosomes were treated with Haelll, Hindlll, EcoRI, and Alul restriction endonucleases and subsequently stained with either Giemsa or ethidium bromide. The results obtained seemed to suggest that the structural organization of specific chromosome regions can play a primary role in determining the cytological effect after digestion with specific restriction endonucleases.

ISSN:1424-8581    

DOI:10.1159/000131973

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

Electron microscopy of synaptonemal complexes in heterokaryotypic Gallus domesticus cockerels revealed that chromosome rearrangements that had been classified by light microscopy as single breaks were in fact reciprocal translocations. A microchromosome provided the centromere for the acentric long arm of chromosome 1 in a rearrangement that had been classified as a centric fission, and microchromosomes were involved in several other rearrangements. The translocation points were mapped in three of the rearrangements.

ISSN:1424-8581    

DOI:10.1159/000131974

出版商:S. Karger AG    

年代:1983

数据来源: Karger

摘要:

We analyzed the karyotypes of nine established human malignant melanoma cell lines derived from two female and six male patients. Each of the cell lines had an aneuploid stemline chromosome number. Analysis of G-banded chromosomes identified a number of altered (marker) chromosomes in these cell lines; in all the lines, chromosome 6 was found to be involved in the marker chromosomes. A review of the literature and these cases showed that of 47 cell lines or primary melanoma cells karyotyped, 38 (80.8%) had a marker involving the 6. We believe that the genetic factor determining melanoma initiation is located in the distal segment of 6q. Deletion of this segment or the entire 6q is responsible for the cell’s (melanoblast or melanocyte) becoming malignant. The proximal segment of 6q and 6p can be involved in marker formatio

ISSN:1424-8581    

DOI:10.1159/000131975

出版商:S. Karger AG    

年代:1983

数据来源: Karger