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PubMed1976

[Duration of meiotic prophase stages during oogenesis in the newt Triturus cristatus cristatus].

The duration of the early stages of meiotic prophase was determined in the oogenesis of T. cristatus cristatus by means of autoradiography. The oocytes were being investigated during 39 days from the moment of 3H-thymidine injection. It was shown that preleptotene lasts 1--2, leptotene ca. 4, zygotene 5 and pachytene 26 days. When studying the preparations obtained 1 day after the injection of 3H-thymidine, the silver grains were found to be localized over the nuclei at all stages of meiotic prophase; this suggests the amplification of rDNA which begins in leptotene-zygotene and ends in early diplotene.

Animals↗
PubMed2000

Sex reversal of the newt Triturus cristatus reared at extreme temperatures.

Crested newt larvae were reared at defined temperatures, either from uncleaved eggs or from early feeding larvae, until metamorphosis when sexual differentiation had occurred. Trials at 18-24 degrees C showed a 1:1 sex ratio. A higher temperature trial produced more males than females, including some XX neomales. Lower temperatures resulted in a significant excess of females, including XY neofemales. Sex reversal only occurred in about half the possible cases on average. Extreme temperatures must perturb the normal XX/XY system of sex determination, to reveal either an ancestral ZZ/ZW system or a still more primitive environmental control. It is suggested that neofemales (but not neomales) could occur in nature.

Animals↗
PubMed1975

[Activity and isoenzymes of lactate dehydrogenase in tissues of amphibians (Xenopus laevis, Ambystoma mexicanum, Triturus alpestris and vulgaris) and the response in the fat body of Xenopus males to gonadotropin injection (author's transl)].

Lactate-dehydrogenase activity was determined by the optical test method using pyruvate as substrate and the isoenzymes were separated by vertical starch gel electrophoresis. Species-specific and organ-specific characteristics of the total activity and the isoenzyme patterns of the four amphibian species are compared with those of rat and mouse. Application of gonadotropin increases the amount of soluble protein and the lactate-dehydrogenase activity in the fat body of Xenopus and the isoenzyme pattern shows a shift of intensity towards the basic bands. Testis does not respond to this treatment.

Adipose Tissue↗