In several asexual taxa, reproduction requires mating with related sexual species to stimulate egg development, even though genetic material is not incorporated from the sexuals (gynogenesis). In cases in which gynogens do not invest in male function, they can potentially have a twofold competitive advantage over sexuals because the asexuals avoid the cost of producing males. If unmitigated, ho...

Diploid gynogenetic Xenopus laevis were obtained by inseminating the eggs with u.v. irradiated spermatozoa, and treating them with hydrostatic pressure to inhibit the expulsion of the second polar body. A u.v. dose of 3000 ergs/mm2 genetically inactivates the spermatozoa without loss of their ability to activate egg development. The use of a genetic marker on very large samples of eggs made it ...

Doubled haploidy methodology is commonly used in many agronomically important crops to speed the development of new cultivars. There are a number of advantages in using haploidy technology in both practical application (varietal development, mutagenesis, transformation) and basic research (genomics, biochemical, and physiological studies). Haploid plants are commonly produced using one of four ...

The assessment of oocytes showing only one pronucleus during assisted reproduction is associated with uncertainty. A compilation of data on the genetic constitution of different developmental stages shows that affected oocytes are able to develop into haploid, diploid, and mosaic embryos with more or less complex chromosomal compositions. In the majority of cases (~80%), haploidy appears to be ...

Ten enzyme loci were mapped in relation to their centromeres in gynogenetic diploid rainbow trout. Gene-centromere map distances, calculated under the assumption of complete interference, range from 1.1 cM for Ldh4 to 50 cM for Sod1. The Idh2 and Est1 loci are linked on the same chromosome arm.-The observation of close to 100% heterozygous gynogenetic diploids for the Sod1 and Mdh3,4 loci sugge...

Mouse spermatozoa were treated with trypaflavine, toluidine blue or nitrogen mustard before fertilization in attempts to destroy the sperm chromosomes and so induce haploid gynogenetic development of the egg. High concentrations of either chemical decreased the activity of spermatozoa. Trypaflavine and toluidine blue had a photodynamic action on spermatozoa and lowered the fertilization rate; n...

Mitotic gynogenesis results in the production of fully homozygous individuals in a single generation. Since inbred fish were found to exhibit an increased frequency of body deformations that may affect their survival, the main focus of this research was to evaluate the ratio of individuals with spinal deformities among gynogenetic doubled haploids (DHs) brown trout as compared to nonmanipulated...

Homomorphic sex chromosomes and rapid turnover of sex-determining genes can complicate establishing the sex chromosome system operating in a given species. This difficulty exists in Xenopus tropicalis, an anuran quickly becoming a relevant model for genetic, genomic, biochemical, and ecotoxicological research. Despite the recent interest attracted by this species, little is known about its sex ...