摘要:

Meiotic studies were carried out on fertile male tertiary trisomic mice with the T(1;13)70H small translocation product, carrying the centromere of chromosome 1 and the telomere of chromosome 13 as the extra element. Approximately 200 primary spermatocytes from each of five males were studied. The only configurations found at diakinesis-metaphase I were 19 bivalents and a trivalent (22%) and 20 bivalents and an univalent (78 %). Among the cells with a trivalent, the majority (92.7%) appears to be of the type (13;13;113). This indicates that, in this case, the telomeric region of chromosome 13 has greater potential to form chiasmata than the proximal region of chromosome 1, which contains centric heterochromatin. From the presence of chromosome 113 in approximately 50 % (N=119) of the secondary spermatocytes, it can be inferred that the formation of an univalent in primary spermatocytes does not lead to loss of the extra chromosome at anaphase-telophase I. The impression was gained that the T70H small marker chromosome (113) can display positive heteropycnotic behavior in the tertiary trisomic males studied. Seven other T70H tertiary trisomic males were mated, generating 301 embryos and fetuses which were karyotyped at either 11 or 18 days of age. Of the 11-day-old embryos, 34.6 % contained the extra chromosome. Of the 18-day-old fetuses, this figure was 46.3 %. Gross differences in litter size of the tertiary trisomic mice occurred both within and between males. At day 12 of gestation, litter size (live embryos) averaged 4.44 ± 2.41 (2V=41). At day 19, the average number of live fetuses was 4.94 ± 2.75 (N=36). The low, albeit variable, reproductive performance of the tertiary trisomic males is caused mainly by lowered sperm productio

ISSN:1424-8581    

DOI:10.1159/000130303

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

In the backcross progeny of single (Robertsonian) metacentric heterozygotes of the mouse, segregational impairment of fertility and reduced litter size are initiated by misdivision of trivalents in meiotic anaphase I. Males heterozygous for the metacentrics Rbl, Rb4, Rb5, and Rb7Bnr of the tobacco mouse series and for the Rb8–10Bnr metacentrics derived from other feral domestic mice produce variable rates of meiotic malsegregation, ranging from 4 % to 26 % unbalanced M II figures. Chromosomally unbalanced gametes become involved in fertilization and produce aneusomic zygotes. Fetal aneuploidy causes developmental breakdown and prenatal death. Mono-somic zygotes are eliminated at an early stage of development. Most aneuploid embryos observed beyond day 8 or 10 of gestation were trisomics. Aneuploidy (trisomy) of the zygotes was considerably more frequent in the progeny of heterozygous females than in that of heterozygous males. There was evidence that this disparity might be the result of a higher nondisjunction rate in the female gametogenesis. Mechanisms of selection against unbalanced male germ cells might operate on a small scale. The highest incidences of aneuploid implants were found (with decreasing frequencies) in the backcross progeny of the Rb(1.3)l, Rb(16.17)7, and Rb(11.13)4Bnr female heterozygotes. With the experimental design used in this study, several trisomic conditions could be observed and their phenotype and developmental profiles described, namely, trisomies (Ts) 1, 3, 4, 10, 11, 12, 13, 16, and 17. Among these, Ts 3, 11, and 17 were characterized by severe developmental impairment and relatively early death, whereas the others could survive until day 13 to 15 or, as in the case of Ts 12, even until day 17. Ts 1 displayed a syndrome of general hypoplasia (fetal runting), whereas exencephaly was found in Ts 12. It was the only trisomy observed in this study that was associated with gross malformatio

ISSN:1424-8581    

DOI:10.1159/000130304

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

Metaphase chromosome preparations of three male and one female Gorilla gorilla were stained to demonstrate quinacrine, Giemsa, centromeric heterochromatin, and, in one case, reverse-Giemsa bands. A standard karyotype is proposed based on chromosome banding pattern, centromeric index, and length. Three types of variation between homologous chromosomes are described: presence or absence of very bright fluorescence of the short arm or satellite region of acrocentric chromosomes, presence or absence of bright quinacrine bands at the distal ends of chromosome arms, and large differences in the size of the heterochromatic region on each of two biarmed chromosomes. At least half the chromosome pairs show polymorphisms of these types. Satellite associations were scored for each animal. In one case the two smallest pairs of chromosomes were preferentially involved in associations.

ISSN:1424-8581    

DOI:10.1159/000130305

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

The segregation of the loci for 26 human enzyme markers was studied in man-Chinese hamster somatic cell hybrids. The results showed synteny of the human loci for fumarate hydratase, UDPG pyrophosphorylase, phosphogluconate dehydro-genase, phosphoglucomutasei, and peptidase-C (chromosome 1). Furthermore, the synteny of the human loci for mannose phosphate isomerase and the leukocytic form of pyruvate kinase was confirmed.

ISSN:1424-8581    

DOI:10.1159/000130306

出版商:S. Karger AG    

年代:1974

数据来源: Karger

摘要:

In this paper a hypothesis is presented which relates chromosome pairing and sterility in males. This hypothesis has been formulated on the basis of data from numerous meiotic systems in the male of Drosophila melanogaster, where the sex chromosomes have heterochromatic pairing sites, sites which must interact in order for postmeiotic development to be normal. The predictions of this theory have been tested in three principal situations: (1) in various sex chromosome systems of man, the mouse, voles, and beetles; (2) in the B chromosome system of the grasshopper Myrmeleotettix maculatus; and (3) in univalent autosomal cases in man and in translocation heterozygotes of the mouse. In all three situations a striking correlation has been obtained between reduction or absence of pairing, on the one hand, and gametogenic breakdown, on the other. It is concluded that a saturation of pairing sites between homologous chromosomes, whether sex chromosomes or autosomes, is essential for regular meiotic or postmeiotic development.

ISSN:1424-8581    

DOI:10.1159/000130307

出版商:S. Karger AG    

年代:1974

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130308

出版商:S. Karger AG    

年代:1974

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130309

出版商:S. Karger AG    

年代:1974

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130310

出版商:S. Karger AG    

年代:1974

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000130302

出版商:S. Karger AG    

年代:1974

数据来源: Karger