The centrosome, the microtubule-organizing center of the cell, is introduced typically by the sperm at fertilization. In some mammals, however, this paternal pattern of inheritance appears to be violated. The hypothesis that the centrosome is maternally inherited was tested during parthenogenesis, polyspermy, and polygyny as well as after recovery from microtubule inhibition at first mitosis. D...

Parthenogenesis - the ability to produce offspring from unfertilized eggs - is widespread among invertebrates and now increasingly found in normally sexual vertebrates. Are these cases reproductive errors or could they be a first step in the emergence of new parthenogenetic lineages?

The molecular mechanisms leading to asexuality remain little understood despite their substantial bearing on why sexual reproduction is dominant in nature. Here, we examine the role of hybridization in the origin and spread of obligate asexuality in Daphnia pulex, arguably the best-documented case of contagious asexuality. Obligately parthenogenetic (OP) clones of D. pulex have traditionally be...

Transitions from sexual reproduction to parthenogenesis may occur along multiple evolutionary pathways and involve various cytological mechanisms to produce diploid eggs. Here, we investigate routes to parthenogenesis in Timema stick insects, a genus comprising five obligate parthenogens. By combining information from microsatellites and karyotypes with a previously published mitochondrial phyl...

Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproducti...

Contagious parthenogenesis-a process involving rare functional males produced by a parthenogenetic lineage which mate with coexisting sexual females resulting in fertile parthenogenetic offspring-is one of the most striking mechanisms responsible for the generation of new parthenogenetic lineages. Populations of the parthenogenetic diploid brine shrimp Artemia produce fully functional males in ...

Mammalian parthenogenesis could not survive but aborted during mid-gestation, presumably because of lack of paternal gene expression. To understand the molecular mechanisms underlying the failure of parthenogenesis at early stages of development, we performed global gene expression profiling and functional analysis of parthenogenetic blastocysts in comparison with those of blastocysts from norm...

Wolbachia is an intracellular symbiont of invertebrates responsible for inducing a wide variety of phenotypes in its host. These host-Wolbachia relationships span the continuum from reproductive parasitism to obligate mutualism, and provide a unique system to study genomic changes associated with the evolution of symbiosis. We present the genome sequence from a parthenogenesis-inducing Wolbachi...