ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Newts with chromosomal mutations have been isolated in female progeny of irradiated males. Detection and analysis of the mutations are based on the study of lampbrush chromosomes of the adult female oocytes. Selection of the mutants, then, concerns viable individuals only, which are apt to give rise to stem lines. The seven mutants have been separated into two groups: simple mutations and complex ones. The first group includes four mutants, three with a reciprocal translocation and one with a pericentric inversion. The translocation carriers have reproduced, but, in the three cases, mortality was high during embryogenesis. The genetic unbalance proves to be the cause, so that survivors correspond to parental karyotypes only. On the contrary, the female with the pericentric inversion, produced offspring, whose primary anomalies, as well as the secondary unbalanced ones (duplication-deficiency) are viable. Meiotic figures allow estimates of the frequency and importance of the unbalance. The second group includes three mutants, the first with two inversions and a reciprocal translocation, the second has two translocations involving five bivalents, the third carries only one chain of translocation, including five bivalents. Complex anomalies are frequent and appear to be viable, as long as they are balanced. One of the mutants gave rise to polyploid off-spring. Three mutations involved the sex bivalent. Suitability of lampbrush chromosomes as a tool of analysis of rearrangements is discussed. Translocations are systematically detected and very small chromosomal rearrangements can be observed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00326508
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