Molecular characterization of embryonic gonads by gene expression profiling in Drosophila melanogaster

Abstract

In many animal species, germ-line progenitors associate with gonadal somatic cells to form the embryonic gonads (EGs) that later develop into functional organ producing gametes. To explore the genetic regulation of the germ-line development, we initiated a comprehensive identification and functional analysis of the genes expressed within the EGs. First, we generated a cDNA library from gonads purified from Drosophila embryos by FACS. Using this library, we catalogued the genes expressed in the gonad by EST analysis. A total of 17,218 high-quality ESTs representing 3,051 genes were obtained, corresponding to 20% of the predicted genes in the genome. The EG transcriptome is unexpectedly distinct from that of adult gonads and includes an extremely high proportion of retrotransposon-derived transcripts. We verified 101 genes preferentially expressed in the EGs by whole-mount in situ hybridization. Within this subset, 39 and 58 genes were expressed predominantly in germ-line and somatic cells, respectively, whereas four genes were expressed in the both cell lineages. The gonad-enriched genes encompassed a variety of predicted functions. However, genes implicated in SUMOylation and protein translation, including germ-line-specific ribosomal proteins, are preferentially expressed in the germ line, whereas the expression of various retrotransposons and RNAi-related genes are more prominent in the gonadal soma. These transcriptome data are a resource for understanding the mechanism of various cellular events during germ-line development.expressed sequence tag ͉ germ cell ͉ retrotransposon ͉ pole cell

Mextli Is a Novel Eukaryotic Translation Initiation Factor 4E-Binding Protein That Promotes Translation in Drosophila melanogaster

“…Other variant translation initiation factors, including eIF4E-3 and eIF4G2, and several variant ribosomal proteins (RpS5b, RpS10a, RpS19b, and RpL22-like) have been identified in expression profiling studies of ovary and embryo GSCs and primordial germ cells (PGCs) (60,61). Taken together with our results, these data indicate that the translational machinery in GSCs and PGCs may differ from that in somatic cells and that these differences may be fundamental to the biology of pluripotent cells.…”

Emerging roles of the SUMO pathway in development

“…High levels of SUMO are found in post-meiotic spermatocytes at the early canoe stage in Drosophila, when histones are removed and substituted by protamines [141]. Moreover, all the components required for sumoylation are co-expressed in Drosophila pole cells, suggesting a role of this pathway in germ-line gene expression [142]. In light of these observations and considering the above-described data regarding the reduction of PIASx (leading to a subtle phenotype in mice testis) and the remarkable participation of sumoylation in gametogenesis and vulva formation in C. elegans [57], a specific and important role of sumoylation in meiosis and germ cell development is expected.…”

RpL22e, but not RpL22e-like-PA, is SUMOylated and localizes to the nucleoplasm ofDrosophilameiotic spermatocytes

“…6 Previous work by others determined that rpL22e-like mRNA is expressed in embryonic and adult gonads and germline cells (gonads, primordial germ cells [PGCs], adult ovary germline stem cells [GSCs] and in adult testes, but not adult ovary from microarray analyses). [7][8][9][10] On the other hand, RpL22e is ubiquitously expressed in embryos and adults. 7,8 With paralogue-specific antibodies (Abs), we determined that RpL22e-like-PA is expressed in a tissue-specific manner, found only in germ cells in adult testes and in fly heads of both sexes.…”

“…[7][8][9][10] On the other hand, RpL22e is ubiquitously expressed in embryos and adults. 7,8 With paralogue-specific antibodies (Abs), we determined that RpL22e-like-PA is expressed in a tissue-specific manner, found only in germ cells in adult testes and in fly heads of both sexes. 6 Thus the gonadal protein expression pattern aligned well with previously reported mRNA expression patterns.…”