A microphotometric study of various Feulgen-stained gametophytic and sporophytic nuclei of Tradescantia paludosa was made to test the hypothesis that DNA is maintained in multiples of a basic unit within all cells of an organism. A multiple relationship was found in all tissues analyzed. The lowest amount of DNA was found in gametophytic nuclei, approximately twice and four times this amount in...

European water frog hybrids Rana esculenta (R. ridibundaxR. lessonae) reproduce hemiclonally, by hybridogenesis: in the germ line they exclude the genome of one parental species and produce haploid gametes with an unrecombined genome of the other parental species. In the widespread L-E population system, both sexes of hybrids (E) coexist with R. lessonae (L). They exclude the lessonae genome an...

BACKGROUND Diploid organisms have two copies of all genes, but only one is carried by each haploid gamete and diploid offspring. This causes a fundamental genetic conflict over transmission rate between alternative alleles. Single genes, or gene clusters, only rarely code for the complex phenotypes needed to give them a transmission advantage (drive phenotype). However, all genes on a male's X ...

Aquaporins are believed to be involved in homeosmotic mechanisms of marine teleosts. Increasing data suggest that these molecular water channels play critical roles associated with the adaptation of gametes and early embryos to the external spawning environment. In this mini-review, we discuss recent studies suggesting the function of aquaporin-mediated fluid homeostasis during spermatozoa acti...

Over a 2-yr period, we investigated the annual cycles of plasma testosterone and corticosterone and the relationships between these hormones and body condition in a wild population of male red-spotted garter snakes, Thamnophis sirtalis concinnus. In the 10 mo that were sampled, a peak in testosterone was observed in late summer during gametogenesis and declining through the spring breeding peri...