ISSN:1424-8581    

DOI:10.1159/000132608

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Electron microscopic observations of synaptonemal complexes of oocytes from chickens heterozygous for two Z-autosome translocations have been used to identify and study the pairing region of the Z and W chromosomes. The two translocations, MN t(Z;1) and t(OH 10), have breakpoints in opposite arms of the Z, and the arm having the breakpoint of MN t(Z;l) is marked by the terminal C + band. In both translocations the short arm of the W was specifically paired with the euchromatic short arm of the Z. In MN t(Z;l) only open quadrivalents (74%) and trivalents plus W univalents (26%) were observed, whereas t(OH 10) exhibited, in addition to the prevalent quadrivalents (62%), III + I (19%) and II + II (19%) configurations. The extent of W pairing was slightly decreased in MN t(Z;1) (68.4% of the W chromosomes paired) and considerably decreased in t(OH 10) (25.3% of the W chromosomes paired). Nonhomologous synapsis occurred regularly at the quadrivalent crosspoint in MN t(Z;1) and also in bivalents from t(OH 10). The recombination nodule normally located in the terminus of the pairing region in normal ZW pairs is present in both translocations without any alteration of its frequency or its strict terminal position. Based on these data and previous observations (Rahn and Solari, 1986), it is proposed that an obligatory recombination event occurs at a locus between 0.7 µm and 0.15 µm of the paired ZW telomeres, establishing a recombinational region and a pseudoautosomal region which determine partial sex-linkage and no sex-linkage, respectively. Most of the pairing region of the ZW pair is nonhomologously paire

ISSN:1424-8581    

DOI:10.1159/000132609

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Laminin B2 is one of the three polypeptide chains of laminin. a large, complex glycoprotein synthesized by a variety of cells and specifically deposited in basement membranes. A cloned cDNA that encodes the human laminin B2 chain was isolated and characterized. The human laminin B2 gene (LAMB2) was assigned to region 1q25→q31 by (1) hybridization of the probe to DNA from a panel of human × mouse somatic cell hybrids containing different human chromosomes and (2) in situ hybridization to isolated metaphase chromosom

ISSN:1424-8581    

DOI:10.1159/000132610

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

An alphoid DNA sequence primarily located on the X chromosome was labeled with biotin and hybridized in situ to preparations of metaphase chromosomes derived from fragile X-affected individuals; hybridization sites were detected immunologically. Labeled X chromosomes were located automatically in digitized images of metaphase cells by searching for the concurrence of a pronounced peak in the longitudinal density profile with the centromere in medium-sized chromosomes having a suitable centromeric index. Approximately 70% of the X chromosomes were detected by a simple classifier; this rate is similar to the automatic classification rate obtained with G-banded metaphases. The frequency of detection of the fragile X site obtained when scored directly from the microscope using this new preparation technique did not differ significantly from the frequency obtained in the same sample by means of a conventional technique. The frequency obtained by visual scoring of digitized images was slightly higher, but not significantly so.

ISSN:1424-8581    

DOI:10.1159/000132611

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The chromosomal location of representative members of the type I and type II subfamilies of the cytokeratin multigene family was determined using specific cDNA probes in Southern blot hybridization with DNA from somatic cell hybrids. Our results show that the gene encoding human type II cytokeratin 4 resides on chromosome 12 and that encoding type I cytokeratin 15 is located on chromosome 17. The results indicate that cytokeratins are not concentrated in only one cluster. The possibility of the existence of separate type I and type II cytokeratin gene clusters is discussed.

ISSN:1424-8581    

DOI:10.1159/000132612

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

In situ hybridization to human meiotic metaphase I (MI) preparations, using the labeled minisatellite core sequence λ33.15, showed clustering of autoradiographic grains principally at or around chiasmata, autosomal sites where crossing-over had occurred. For the XY bivalent, the pairing region formed between the terminal regions of the two short arms (Xpter-Ypter), was also a principal site of labeling; in addition, the terminal region of the X long arm (Xqter) was labeled. Control experiments using a member of the human Alu family of dispersed repeated DNA sequences showed a much more randomized grain distribution, with clustering over chiasmata being far less obvious. The data provide support for the suggestion that polymorphic minisatellite regions within the human genome might play a significant role in pairing and/or recombination

ISSN:1424-8581    

DOI:10.1159/000132613

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Eight single-copy DNA probes specific for human chromosome 3 were isolated by screening a human chromosome 3-derived genomic library. Southern blot analyses of DNAs isolated from a panel of somatic cell hybrids allowed us to regionally assign all probes to subregions on chromosome 3. Three clones were localized to the short arm of chromosome 3 (3p21→pter), two to the long arm (3q21→qter), and three to the 3q21→3p21 sub-region. Six of these DNA sequences map to regions overlapping a segment of chromosome 3 (3p14→p23) frequently deleted in small cell lung cancer cells. Restriction fragment length polymorphism analyses indicate that at least three of the eight single-copy probes studied show Msp1 or Bg/II polymorphisms. This library is a useful source of chromosome 3-specific

ISSN:1424-8581    

DOI:10.1159/000132614

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Using a rat creatine kinase (brain form) cDNA clone for in situ hybridization, we have localized the gene in both the human and the rabbit complement. An analysis of the data shows that the locus in the human is at 14q32, confirming previous assignments based on somatic hybridization studies and Southern blot analysis. In the rabbit, significant accumulation on 20q13→qter with the predominant labeling at the end of the chromosome provides evidence for the localization of the gene at this site. The heterologous hybridizations of a rat probe to both human and rabbit metaphases underscore the highly conserved nature of the sequences for this enzym

ISSN:1424-8581    

DOI:10.1159/000132615

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

We present here the first detailed replication banding study of a marsupial species using the BrdU-replication technique. A comparison of the structural and replication bands of the chromosomes of Sminthopsis crassicaudata clearly demonstrates that the replication behavior is the same as that described for the chromosomes of eutherians. The early replicating segments correspond to R-bands, whereas the late-replicating regions tend to be situated within Q- and C-bands. Use of this technique clearly reveals an early and late replicating X chromosome. The very small Y chromosome can be subdivided into two replication segments, but no replication homologies can be demonstrated between the X and Y chromosomes of S. crassicaudata.

ISSN:1424-8581    

DOI:10.1159/000132616

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Restriction fragment length polymorphisms at 53 autosomal loci were screened for heterozygosity in 40 colorectal cancer patients. The DNA pattern in constitutional versus tumor/ polyp tissue was compared. More than half of the markers tested were of the VNTR (variable number of tandem repeats) type, giving the patient panel a higher informational content, since the frequency of individuals heterozygous for a particular marker is increased. Loss of alleles was revealed in 40% of the tumors from constitutionally heterozygous patients at the chromosome 17p loci, identified by the markers YNH37 and YNZ22. Similar losses were also detected on other autosomes, but at a significantly lower frequency. Our results suggest that hemi/homozygosity of 17p alleles plays a role in the development of a major subset of colorectal carcinomas. Similar observations regarding other autosomal loci may be interpreted as random losses in these tumors, or they may indicate loci important to minor clinical subclasses of colon carcinomas.

ISSN:1424-8581    

DOI:10.1159/000132617

出版商:S. Karger AG    

年代:1988

数据来源: Karger