Developmental programs are executed by tightly controlled gene regulatory pathways. Here, we combined the unique sample retrieval capacity afforded by laser capture microscopy with analysis of mRNA abundance by CEL-Seq (cell expression by linear amplification and sequencing) to generate a spatiotemporal gene expression map of the Caenorhabditis elegans syncytial germline from adult hermaphrodites and males. We found that over 6000 genes exhibit spatiotemporally dynamic expression patterns throughout the hermaphrodite germline, with two dominant groups of genes exhibiting reciprocal shifts in expression at late pachytene during meiotic prophase I. We found a strong correlation between restricted spatiotemporal expression and known developmental and cellular processes, indicating that these gene expression changes may be an important driver of germ cell progression. Analysis of the male gonad revealed a shift in gene expression at early pachytene and upregulation of subsets of genes following the meiotic divisions, specifically in early and late spermatids, mostly transcribed from the X chromosome. We observed that while the X chromosome is silenced throughout the first half of the gonad, some genes escape this control and are highly expressed throughout the germline. Although we found a strong correlation between the expression of genes corresponding to CSR-1-interacting 22G-RNAs during germ cell progression, we also found that a large fraction of genes may bypass the need for CSR-1-mediated germline licensing. Taken together, these findings suggest the existence of mechanisms that enable a shift in gene expression during prophase I to promote germ cell progression.
Bibliographical noteFunding Information:
We thank Charles R. Vanderburg of the Harvard Neuro-Discovery Center and the Technion Genome Center for technical assistance, and Yuji Kohara for kindly granting us permission to use in situ data from the NEXTDB database (version 4.0). The N2 worms were provided by the Caenorhabditis Genetics Center, which is funded by the U.S. National Institutes of Health (NIH) Office of Research Infrastructure Programs (P40 OD-010440). This work was supported by Israel Science Foundation grants 1283/15 and 2090/15 to Y.B.T., a European Research Council grant (Evo-DevoPaths) and a European Molecular Biology Organization Young Investigator Program to I.Y., and NIH grant R01 GM-072551 to M.P.C.
© 2018 by the Genetics Society of America.
- C. elegans
- Gene expression