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Research has been conducted on RNAi, gene silencing by double-stranded RNA. Results indicate that RNAi is established in Drosophila female germe line and that RNAi regulation and oogenesis translation control are mediated by similar mechanism.

Mutations in a gene called ebi were identified in screening for mutations that affect eye development. Genetic analysis found that ebi functions in EGFR pathways regulating aspects of gametogenesis and in imaginal disc development. The newly identified gene is quite homologous to proteins in plants, yeast and humans and is related structurally to Cdc4/Sel-10/Slimb. It has been shown that ebi is necessary in R7 development for down-regulating Ttk88 responding to epidermal growth factor (EGFR) signals. Mutations in ebi (ital) and Egfr (ital) give rise to similar phenotypes. They interact genetically, and ebi regulates EGFR receptor signaling pathways in Drosophila. The new gene does not have genetic interactions with other RTKs or with components of the canonical Ras/MAP kinase pathway.

Gene transcription repression is basic to nuclear hormone receptors. Cell-specific repression by nuclear receptors relates to levels of nuclear receptor corepressor (N-CoR) protein, based on recent experimentation. Aimed proteolysis of transcriptional coregulators has been found to be a path for cell-specific regulation of gene transcription.

The study of newly evolved genes has long fascinated biologists, but large-scale studies of their expression dynamics and molecular function have provided conflicting interpretations of their biological impact. In this issue of Genes & Development , Kondo and colleagues (pp. 1841-1846) use extensive transcriptomic resources and current CRISPR/Cas9 technology to re-examine the functional impact of newly evolved genes in Drosophila and find evidence of their biological impact on male reproduction., (© 2017 Nyberg and Carthew; Published by Cold Spring Harbor Laboratory Press.)

In the Drosophila RNA interference (RNAi) pathway, small interfering RNAs (siRNAs) direct Argonaute2 (Ago2), an endonuclease, within the RNA-induced silencing complex (RISC) to cleave complementary mRNA targets. In vitro studies have shown that, for each siRNA duplex, RISC retains only one strand, the guide, and releases the other, the passenger, to form a holo-RISC complex. Here, we have isolated a new Ago2 mutant allele and provide, for the first time, in vivo evidence that endogenous Ago2 slicer activity is important to mount an RNAi response in Drosophila. We demonstrate in vivo that efficient removal of the passenger strand from RISC requires the cleavage activity of Ago2. We have also identified a new intermediate complex in the RISC assembly pathway, pre-RISC, in which Ago2 is stably bound to double-stranded siRNA.