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要旨:
The parasitic females of the nematode genus Strongyloides live in the small intestines of their hosts and reproduce parthenogenetically. In addition to producing parasitic offspring (homogonic life cycle), they can also form a facultative free-‐ living sexual generation (heterogonic life cycle). The entire progeny of the free-‐living generation is female and parasitic. We are further characterizing the male specific chromatin diminution event we identified in S. papillosus (Nemetschke et al 2010 Curr Biol 20:1687-‐1695). We also perform comparative analyses of chromosome numbers and sex chromosomes in different species of Strongyloides and we ask if X chromosome dosage compensation exists in Strongyloides spp. The switch between the homogonic and heterogonic cycles is likely homologous with the dauer switch in C. elegans. Nevertheless, many of the factors involved in the control of these switches are likely to differ. To identify genes that control this switch in S. ratti we mutagenized a strain (ED321) that predominantly undergoes the heterogonic life cycle. Analysis of mutants with an elevated proportion of homogonic development is in progress. Additionally we performed transcriptome comparisons between young larvae of ED321 and ED5, which forms very few free-‐living individuals. We compared three samples: i) ED321 progeny of the parasitic generation (destined to form free-‐living adults of both sexes); ii) ED5 progeny of the parasitic generation (destined to form parasitic females) and iii) ED321 progeny of the free-‐living generation (destined to form parasitic females). The number of differentially regulated genes is relatively small (about 370 genes across all comparisons). Interestingly, the two samples that were the progeny of parasitic mothers but bound for different life cycles (i and ii) differed much less from each other than did the two samples that were both destined to form infective larvae but were the progeny of parasitic or free-‐living parents respectively (ii and iii).
