PT - JOURNAL ARTICLE AU - Christopher Kraus AU - Philipp H. Schiffer AU - Hiroshi Kagoshima AU - Hideaki Hiraki AU - Theresa Vogt AU - Michael Kroiher AU - Yuji Kohara AU - Einhard Schierenberg TI - Differences in the genetic control of early egg development and reproduction between <em>C. elegans</em> and its parthenogenetic relative <em>D. coronatus</em> AID - 10.1101/171769 DP - 2017 Jan 01 TA - bioRxiv PG - 171769 4099 - http://biorxiv.org/content/early/2017/08/02/171769.short 4100 - http://biorxiv.org/content/early/2017/08/02/171769.full AB - Background The free-living nematode Diploscapter coronatus is the closest known relative of C. elegans with parthenogenetic reproduction. It shows several developmental idiosyncracies, for example concerning the control of meiosis and embryonic axis formation [1]. Our recent genome analysis [2] provided some support for the view that D. coronatus is a product of interspecies hybridization. Here we present additional data towards this assumption. Based on genomic and transcriptomic data we try to better understand the molecular basis of developmental idiosyncrasies in this species in an evolutionary context by comparison with selected other nematodes.Results In a genomic comparison between D. coronatus, C. elegans, other representatives of the genus Caenorhabditis and the more distantly related Pristionchus pacificus and Panagrellus redivivus, certain genes required for normal embryogenesis in C. elegans were found to be restricted to the genus Caenorhabditis. The mRNA content of early D. coronatus embryos was sequenced and compared with similar stages in C. elegans and Ascaris suum. We identified 350 gene families transcribed in the early embryo of D. coronatus but not in the other two nematodes. Looking at individual genes transcribed early in D. coronatus but not in C. elegans and A. suum we found that orthologs of most of these are present in the genomes of the latter species as well, suggesting heterochronic shifts with respect to expression behavior. Considerable divergence between alleles lends further support to the view that D. coronatus may be the result of an interspecies hybridization. Expression analysis of early acting single copy genes yield no indication for silencing of one parental genome.Conclusions Our comparative cellular and molecular studies support the view that the genus Caenorhabditis differs considerably from the other studied nematodes in its control of development and reproduction. The easy-to-culture parthenogenetic D. coronatus, with its high quality draft genome and only a single chromosome when haploid, offers many new starting points on the cellular, molecular, and genomic level to better understand alternative routes of nematode development and reproduction.