摘要:

The five North American species of the stickleback family Gasterosteidae were studied karyologically. They constitute two diploid-count groups; one with 46 includes Λpeltes quadracus and Culaea inconstans, and the other with 42 consists of Gasterosteus aculeatus, G. wheatlandi and Pungitius pungitius. The common occurrence of a distinctly large submetacentric pair in complements of all five species suggests a monophyletic origin of this character. The consistent presence of three additional large chromosome pairs in all members of the 2n = 42 group suggests their close relationship. Culaea probably possesses the closest karyotype to that of the progenitor of the 2n = 42 group. Apeltes is perhaps an offshoot of, and distantly related to, their common ancestor. The phylogenetic scheme constructed from the karyological data agrees with that constructed from grosmorphological and behavioral characters. The possible routes of chromosome evolution among the species and genera are discussed. Although pericentric inversions or reciprocal translocation or both might have achieved specific and generic differences, centric fusions or tandem translocations or both are required to separate the 2n = 46 group from the 2n = 42 group. Both the female Apeltes quadracus and the male Gasterosteus wheatlandi had a heteromorphic pair that was not detectable in the karyotype of the opposite sex. This may indicate a probable occurrence of cytologically expressed heterogamety in these two species

ISSN:1424-8581    

DOI:10.1159/000130102

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

A malformed infant and her phenotypically normal relatives were studied cytogenetically. Mosaicism consisting of normal cells and cells carrying an abnormally long chromosome 16 was detected in members of three generations of the same family. The abnormal chromosome presented a terminal secondary constriction and an extra chromosome segment. Breakage of the abnormal secondary constriction and separation of the extra chromosome segment from the abnormal No. 16 occurred in all the carriers in the family. The proband also presented selective endoreduplication of the abnormal segment with subsequent successive separation of the extra fragments formed. The cytogenetic mechanisms involved in the production of these chromosome aberrations and their possible phenotypical consequences are discussed.

ISSN:1424-8581    

DOI:10.1159/000130103

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

An abnormal subtelocentric, satellited chromosome which was found in a patient with chronic lymphocytic leukemia and in 50% of his family members was studied autoradiographically. It was demonstrated that this chromosome is an altered chromosome 13 with elongated short arms. The theories as to the origin of the extra chromatin were discussed in the light of the autoradiographic results. Some evidence is presented that other chromosomes of the D group may be involved in a similar anomaly.

ISSN:1424-8581    

DOI:10.1159/000130104

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Chromosomal rearrangements are described in a three-generation family whose members were all normal but for the propositus, who had phenotypic abnormalities suggestive of Patau’s syndrome. The rearrangements appeared to involve chromosomes of the D and E groups in four members of the family, and in the mother and the abnormal propositus, who had identical karyotypes, there was also a questionable abnormality of a B chromosome. Autoradiographic studies indicated that chromosomes 13 and 17 may be involved in the translocation and that the B-group abnormality involved possibly a chromosome No. 5. Genetic-marker studies were noncontributory. The explanation favored for the rearrangement was an insertion type of exchange following three breaks in the D and E groups, and hence the abnormal propositus could be explained as an example of recombinational imbalanc

ISSN:1424-8581    

DOI:10.1159/000130105

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Somatic chromosomes obtained from corneal squash preparations of nine species representing four genera of the anuran family Leptodactylidae were analyzed and compared. Batrachyla leptopus, Crossodactylus gaudichaudii, Cyclorhamphus fuliginosus, Eupsophus coppingeri, E. taeniatus and Thoropa miliaris were found to possess 26 chromosomes (n = 13). E. roseus has 30 chromosomes (n = 15), E. vertebralis has 28 chromosomes (n = 14) and E. nodosus has 22 chromosomes (n = 11). The karyotypes of some species of Eupsophus are more similar intergenerically than intragenerically. This suggests that Eupsophus is an unnatural assemblage of species. Characters previously used to delimit genera of leptodactylid frogs are criticized.

ISSN:1424-8581    

DOI:10.1159/000130106

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

Replication patterns of the duplicate-type sex chromosomes have been studied in bone-marrow cells in vivo and fetal cells in vitro of the Indian house shrew, Suncus murinus. The sex chromosomes start their replication along with the rest of the chromosomes in the early S but show asynchrony in the late S phase. The Y chromosome finishes its DNA synthesis earlier than the X chromosome and the autosomes in male bone-marrow and fetal cells. On the other hand, the X chromosomes in female cells behave differently in bone-marrow and fetal cells. One of the X’s replicates early in fetal cells. But there is no definite pattern in bone-marrow cells – the X chromosomes can replicate either early or late. The duplicate-type X chromosome of Suncus is unique among mammals in its replication; the pattern does not conform to the hypothesis that except 5% of the haploid complement residing in the X chromosome is functional. The correlation between genetic activity and late or early replication is discussed. It is proposed that heteropycnosis is merely a reflection of out-of-phase replication and not necessarily genetic inertn

ISSN:1424-8581    

DOI:10.1159/000130107

出版商:S. Karger AG    

年代:1970

数据来源: Karger

摘要:

We have studied by means of autoradiography a case of D/G translocation after terminal labelling of leukocyte cultures with 3H-thymidine. The D-group chromosome involved in the translocation has been identified as a No. 13 and the G-group chromosome as a No. 21. This is the first case of a 13/21 translocation over a published total of 40 cases.

ISSN:1424-8581    

DOI:10.1159/000130108

出版商:S. Karger AG    

年代:1970

数据来源: Karger