ABOUT one percent of the 3,000 species of lizards in the world have all-female populations in which reproduction seems to be by true parthenogenesis (as opposed to gynogenesis or hybridogenesis). For some species, no males have ever been found at any localities. For a few species, all-female populations occur at some localities, bisexual populations at others. (In unisexual populations all norm...

Parthenogenetic embryos of mice die shortly after implantation and characteristically contain poorly developed extraembryonic tissue. To investigate the basis of the abnormal development of parthenotes, we combined them with normal embryos to produce chimeras and examined the distribution of the parthenogenetically derived cells during preimplantation and early postimplantation development. The...

Two new species of Fergusobia are described. Both were collected from flat leaf galls from South Australia, one on Eucalyptus microcarpa and the other on E. porosa. Fergusobia microcarpae n. sp. Davies is characterised by the combination of a C-shaped parthenogenetic female with a short, broadly rounded conoid tail, an arcuate to open C-shaped infective female with an hemispherical tail tip, an...

Mammalian parthenogenetic embryos (pE) are not viable due to placental deficiency, presumably resulting from lack of paternally expressed imprinted genes. Pluripotent parthenogenetic embryonic stem (pES) cells derived from pE could advance regenerative medicine by avoiding immuno-rejection and ethical roadblocks. We attempted to explore the epigenetic status of imprinted genes in the generation...

Human leukocyte antigen-homozygous parthenogenetic stem cells (pSC) could provide a source of progenitors for regenerative medicine, lowering the need for immune suppression in patients. However, the high level of homozygosis and the lack of a paternal genome might pose a safety challenge for their therapeutic use, and no study so far has evaluated the spread and significance of gene expression...

This review aimed to give a brief account on the principles, techniques and applications for in vitro production (IVP) of embryos and related biotechnologies. IVP of embryos provides an excellent source of low cost embryos for basic research on developmental biology and physiology and for the application of emerging biotechnologies such as nuclear transfer, production of transgenic animals, emb...

Root-knot nematodes (genus Meloidogyne) have been the subject of recent and numerous studies of genetic variation because of the need to develop molecular diagnostics for the four globally distributed, parthenogenetic species that are significant agricultural pests. Our analysis of Meloidogyne mtDNA improves on previous studies: (i) by examining restriction site polymorphism among a large numbe...

Despite the two-fold reproductive advantage of asexual over sexual reproduction, the majority of eukaryotic species are sexual. Why sex is so widespread is still unknown and remains one of the most important unanswered questions in evolutionary biology. Although there are several hypothesized mechanisms for the maintenance of sex, all require assumptions that may limit their applicability. I su...

Organisms with coexisting sexual and asexual populations are ideal models for studying the consequences of either reproductive mode on the quantitative genetic architecture of life-history traits. In the aphid Rhopalosiphum padi, lineages differing in their sex investment coexist but all share a common parthenogenetic phase. Here, we studied multiple genotypes of R. padi specialized either for ...

Digenetic trematodes have a complex life cycle that involves at least two hosts: a molluscan host, where the worms reproduce asexually, and a vertebrate host, where they reproduce sexually. In some species of the family Microphallidae, all (N = 500-1,000) of the asexual progeny produced in the molluscan host are consumed together by the vertebrate host, where they hatch and mature. This gives a...