摘要:

Evidence is presented that pairing between the human X and Y chromosomes could be more extensive at early pachytene than has previously been supposed and could involve even the entire euchromatic portion of the Y chromosome. Following desynapsis over the major part of the X and Y axes, a small paired segment of Xp and Yp remains into late pachytene. Association between the distal tips of Xq and Yq can also be observed in about one half of the spermatocytes examined. A hypothesis linking meiotic pairing to early replicating sites along the chromosomes is proposed.

ISSN:1424-8581    

DOI:10.1159/000132070

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Fifteen gene loci for constitutive enzymes previously localized to specific owl monkey chromosomes of karyotypes III, V, and VI are confirmed by their assignments to homologous chromosomes of owl monkey karyotypes I, II, IV, and VII. The syntenic mapping of LDHA and GPI on a large metacentric, II–2, and the separate assignment of these two loci to two acrocentrics, I–9 and I–15, provide genetic evidence supporting the proposed fusion-fission event that characterized the karyotypic difference between owl monkeys inhabiting Colombia and the Panama Canal Zone. Moreover, the proposed hypothesis on chromosome polymorphism among the Colombian owl monkeys with karyotypes II, III, and IV, resulting from a fusion-fission event involving one metacentric and two subtelocentric pairs, is supported by the assignment of LDHB and MDH1 to the large metacentric I–2 and the separate localization of these two gene loci to II–13 and II–14, r

ISSN:1424-8581    

DOI:10.1159/000132071

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A chromosome polymorphism was detected between two early passage euploid Chinese hamster cell strains when a fluorescence shift of the small metacentric No. 9 chromosome was resolved by flow cytometry. The characteristics of the polymorphism were studied using cultures established from ear clippings taken from 16 additional hamsters from our breeding colony. Additional variants of chromosome 9 were detected using flow cytometry, and a subset of these variants were analyzed by G- and C-banding. An increase of fluorescence recorded by flow cytometry correlated with an increase of centromeric heterochromatin. Autosomal normalization of the flow karyotype from 18 different animals indicated three distinct peak positions for chromosome 9. The results indicate that a discrete block of constitutive heterochromatin may be present in one or two extra copies within the small inbred colony of hamsters studied. To determine the inheritance patterns, hamsters with known polymorphic No. 9 chromosomes were bred. The flow karyotypes derived from the offspring of these matings provide strong evidence that chromosomal polymorphisms are inherited in Mendelian fashion.

ISSN:1424-8581    

DOI:10.1159/000132072

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Pregnant female common shrews were collected from an area of Robertsonian polymorphism, involving five different arm combinations, around Oxford (England). The females and their fetuses were karyotyped, and the karyotypes of the sires were deduced. Ten pregnancies where at least one parent was known to be either a single or double Robertsonian heterozygote were available for analysis. From these pregnancies, upper and lower estimates of anaphase I nondisjunction arising from Robertsonian heterozygosity were calculated to be 1.0–2.5% per heterozygous arm combination and 1.5–3.7% per heterozygous parent. One trisomic fetus with retarded development was identified. This trisomy can be attributed to anaphase I nondisjunction of a trivalent in a female Robertsonian heterozyg

ISSN:1424-8581    

DOI:10.1159/000132073

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

We have mapped the albumin locus (ALB) in the owl monkey, Aotus trivirgatus, using a cloned human albumin gene probe, pcHSA 33-1. Rodent-owl monkey somatic cell hybrids were used to map the owl monkey albumin locus in three subgroups of Aotus, karyotypes II, V, and VI. Segregation analysis of the molecular hybridization pattern of pcHSA 33-1 in the somatic cell hybrids indicated that the albumin locus maps to chromosome 9 of owl monkey karyotype II, chromosome 12 of karyotype V, and chromosome 1 of karyotype VI. This assignment provides evidence for the homology of these three chromosomes and supports the hypothesis of Ma on the formation of chromosome 1 in karyotype VI.

ISSN:1424-8581    

DOI:10.1159/000132074

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Data are presented establishing a direct correlation between 3-aminobenzamide-induced sister chromatid exchange (SCE) frequency and the level of bromodeoxyuridine (BrdU) incorporated into DNA. In addition, it is shown that most of the SCEs are induced in the second cell cycle, in which BrdU-containing DNA is used as the template for replication.

ISSN:1424-8581    

DOI:10.1159/000132075

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Chromosomes from cultured fibroblasts of four cottontail species (Sylvilagus audubonii, 2n = 42; S. idahoensis, 2n = 44; S. nuttallii, 2n = 42; and S. palustris, 2n = 38) were analyzed using G- and C-banding techniques. The evolutionary restructuring of the genomes of these species was traced by comparing their banded chromosomes to those of Lepus saxatilis, a species of hare in which the leporid ancestral karyotype is thought to have been conserved. Chromosomal evolution appears to have proceeded primarily through changes in the amount and distribution of heterochromatin and through fixation of Robertsonian fusions. Excluding heterochromatic differences, S. audubonii and S. nuttallii are karyotypically very similar, as are S. aquaticus and S. palustris (previously reported). The genome of the taxonomically controversial species S. idahoensis, compared to other cottontail species, is markedly impoverished in C-band material. These data and those of cottontail species previously described in the literature are incorporated in two alternative phylogenetic schemes.

ISSN:1424-8581    

DOI:10.1159/000132076

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

An extra segment in chromosome 1 between bands C5 and D has been found in wild mouse populations. Its size varies between 6.1 % and 30.1 % of the length of a standard chromosome 1. It differs among individuals and populations but is constant in a genetically homogeneous line. According to its staining properties and variation in length it is a homogeneously staining region (HSR), a kind of segment otherwise found only in cell lines under strong selection and in tumor cells. G-banding gives a homogeneous staining of medium intensity. With C-banding, staining is positive, though lighter than that of centromeric heterochromatin. Fluorescence is dull with Hoechst 33258 and bright with mithramycin. The extra segment does not contain mouse satellite DNA sequences in any quantity detectable by in situ hybridization. Such an extra segment was found in several European populations of mice from Spain to Russia. It is carried through the germ line. It has been introduced into a laboratory mouse strain, and, by recombination, inserted into a Robertsonian metacentric chromosome for easier handling and identification.

ISSN:1424-8581    

DOI:10.1159/000132077

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

A young woman with normal gonadal development and mild mental retardation was found to have a small de novo interstitial deletion of most of band Xp21, karyotype designation 46, X, del(X) (pter→p21.3::p21.1→qter). Replication studies on lymphocytes and skin fibroblasts revealed that in 45% of cells the normal X was late replicating. Somatic cell hybrids between her fibroblasts and HPRT-deficient Chinese hamster cells were obtained and selected for and against retention of the active human X chromosome. In several independent hybrids the deleted X was retained in the active state. Partial ornithine transcarbamylase (ornithine carbamoyltransferase EC 2.1.3.3) (OTC) deficiency was documented by elevated urinary orotic acid excretion and increased serum glutamine after a protein load. This confirms the mapping of the structural gene for OTC to this deletion. Testing of neutrophil function revealed heterozygosity for chronic granulomatous disease (CGD) suggesting that a gene for CGD maps within the deletion. Thus, X inactivation mosaicism is also present in hepatocytes and neutrophilic granulocytes. Random X inactivation in a female with an Xp deletion has not been previously reported. The cells from this patient and the somatic cell hybrids containing her deleted X chromosome in the absence of the normal X provide material for the precise mapping of X linked genes and DNA sequences on the short arm of the human X chromos

ISSN:1424-8581    

DOI:10.1159/000132078

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

We report a method for producing high-resolution G-bands on chromosomes of normal and neoplastic human cells after hybridization of 3H-labeled probes to the chromosomes and after autoradiography.

ISSN:1424-8581    

DOI:10.1159/000132079

出版商:S. Karger AG    

年代:1984

数据来源: Karger