摘要:

Several mouse mutations cause unstable locomotion, tremor, seizures, and a reduced lifespan because of deficient myelin formation in the central nervous system. Mutant alleles at the shiverer (shi) locus are the only ones in this series with a selective molecular defect, namely, in myelin basic proteins (MBPs), which are virtually absent in shi homozygotes and 50% reduced in heterozygotes. In the present study, backcross and intercross matings indicate recombination of 21.2 ± 3.3% between myelin deficient, shimld, and fused phalanges, syfp, a marker near the middle of chromosome 18. Recombination of shimld with twirler (Tw), a marker near the centromere, is 45.7 ± 4.9%. Thus, the shi locus maps near the distal end of mouse chromosome 18 and is the first available marker for this region. Given the evidence of other workers that an MBP locus maps to the same mouse chromosome, and that part of this chromosome may be syntenic with an MBP-PEPA region on human chromosome 18, it is likely that shi is in or near an MBP gen

ISSN:1424-8581    

DOI:10.1159/000132151

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

A restriction endonuclease fragment derived from a cloned portion of human genomic DNA corresponding to the myelin basic protein gene has been used to map the position of this gene by in situ hybridization to human metaphase chromosomes. Ten percent of the radioactively labeled sites observed were on chromosome 18. Eighty-four percent of the grains on chromosome 18 were located within the region corresponding to 18q22→qter. This represents a greater than 10-fold increase in labeling at this position over the background grain distribution found along all of the other chromosome

ISSN:1424-8581    

DOI:10.1159/000132152

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

A single population of the iguanid lizard, Sceloporus grammicus, was found to have fission polymorphisms in three of four metacentric macrochromosome pairs. This variation resulted in eight different karyotypes in a sample of 24 lizards. Of these 24 lizards, 7 were single heterozygotes, 11 were double heterozygotes, and 1 was a triple heterozygote. Meiotic analyses of males heterozygous for different combinations of fissions indicated completely normal disjunction and production of chromosomally balanced gametes. The polymorphisms in this population did not appear to deviate strongly from Hardy-Weinberg equilibrium. There was no evidence of selection against chromosomal heterozygotes in this population.

ISSN:1424-8581    

DOI:10.1159/000132153

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The presumed ancestral karyotype of Muridae, previously reconstructed, is compared with that of a selected Cricetidae species, Akodon a arviculoides. Most of the chromosomes of the presumed ancestral chromosomes of Muridae are homeologous to chromosome arms or segments in the Akodon karyotype. This result strengthens the validity of the reconstruction of the ancestral karyotype for both Muridae and Cricetidae.

ISSN:1424-8581    

DOI:10.1159/000132154

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Two repetitive DNA fragments located on the mouse X chromosome are described. The fragments were isolated from a lambda phage library enriched in X-chromosomal sequences by flow sorting. Both fragments, which are repeated 20 to 50 times in the genome, were mapped to the mouse X chromosome by Southern blot hybridization to DNA from hybrid cells retaining the mouse X chromosome, by dosage analysis, and by in situ hybridization to mouse chromosomes. In mouse strain C57BL/10BK, one fragment appeared to be located only on the X chromosome, while the other fragment had homologous sequences on chromosome 11 in addition to the X chromosome. The latter fragment showed DNA variants between mouse strains, which are potentially useful for mapping. Both fragments cross-hybridized to another mouse species: Mus caroli. In this species, each fragment appeared to be located on the X chromosome, indicating that some X-chromosome repetitive sequences are partially conserved. In addition, one fragment cross-hybridized to human DNA.

ISSN:1424-8581    

DOI:10.1159/000132155

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

A 4.4-kb PstI fragment containing the entire β-gene of the human β-globin gene cluster plus both 5’- and 3’-flanking sequences was used as a probe to study the chromosomal localization of the β-gene by in situ hybridization. Using random oligonucleotides as primers, the β-gene DNA was 3H-labeled with the large fragment of DNA polymerase I (Klenow fragment) to a specific activity of 1.2 × 108 cpm/µg. Almost 80% of hybridization grains observed were located on the distal short arm of chromosome 11. High-resolution chromosome analysis suggests a more precise location of the β-gene to region 11p

ISSN:1424-8581    

DOI:10.1159/000132156

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

It has been known for some time that there is an association between chronological aging and X-chromosome aneuploidy in peripheral blood lymphocyte cultures from females. In an attempt to elucidate the mechanism of X-chromosome aneuploidy in aging females, we used a BrdU late-labeling technique to determine the X-inactivation pattern in 45, X and 47, XXX lymphocytes of older women. In 50 of 58 X-aneuploid cells the inactive X chromosome was missing or extra. This implies that either the inactive X has a special propensity for mitotic errors or mitotic errors occur at random but subsequent selection is less stringent against cells with a missing or additional inactive X chromosome than against aneuploid cells involving the active X chromosome. Evidence is presented in favor of the former hypothesis.

ISSN:1424-8581    

DOI:10.1159/000132157

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

In situ hybridization of a 3H-labeled probe containing a fragment from PRP-1, a genomic clone with human salivary proline-rich protein gene sequences, revealed significant labeling on the short arm of human chromosome 12 in metaphase preparations from two individuals. Fifty-three percent of metaphases exhibited labeling on one or both chromosomes 12. Additional cells scored at the 850–1,000 band level revealed a significant proportion (52% [32/61] grains, p < 0.005) of the labeled sites on chromosome 12 to be on band 12pl3.2. This probe for a human salivary proline-rich protein gene fragment, probably PMS, is from a cluster of 13 linked genes designated as the human salivary protein complex (SPC). Studies of the DNA of human-mouse somatic-cell hybrids have assigned the SPC to chromosome 12, but have not provided a regional localization (Azen et al., 1985). This paper reports the localization of the SPC to a specific chromosomal band, 12pl3.

ISSN:1424-8581    

DOI:10.1159/000132158

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Using Chinese hamster/mouse somatic cell hybrids segregating hamster chromosomes, we assigned 15 enzyme genes to six different Chinese hamster autosomes. Of the 15 loci, three genes, HK1, PEPC, and SORD, were newly assigned to chromosomes 1, 5, and 6, respectively, while ENOl, PGD, and PGM1 were assigned to the long arm of chromosome 2, in the segment 2q113→qter. The locations of the following loci were confirmed: ESD, NP, and PEPB on chromosome 1, ME1 and MPI on chromosome 4, AK1 on chromosome 6, and GP1 and PEPD on chromosome 9. Comparative mapping of Chinese hamster and laboratory mouse chromosomes revealed conservation of syntenic groups and extensive banding homology between the Chinese hamster and mouse chromosomes on which homologous enzyme markers have been mappe

ISSN:1424-8581    

DOI:10.1159/000132159

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The present report describes a double synchronization technique that selects for first- and second-division metaphases in human lymphocyte cultures. The technique ensures high mitotic indices without elaborate handling of cultures. Combined with appropriate band induction, this technique provides a high yield of uniform metaphases with well-defined high-resolution banding.

ISSN:1424-8581    

DOI:10.1159/000132160

出版商:S. Karger AG    

年代:1985

数据来源: Karger