A putative de novo evolved gene required for spermatid chromatin condensation in Drosophila melanogaster.

Comparative genomics has enabled the identification of genes that potentially evolved de novo from non-coding sequences. Many such genes are expressed in male reproductive tissues, but their functions remain poorly understood. To address this, we conducted a functional genetic screen of over 40 putative de novo genes with testis-enriched expression in Drosophila melanogaster and identified one gene, atlas, required for male fertility. Detailed genetic and cytological analyses showed that atlas is required for proper chromatin condensation during the final stages of spermatogenesis. Atlas protein is expressed in spermatid nuclei and facilitates the transition from histone- to protamine-based chromatin packaging. Complementary evolutionary analyses revealed the complex evolutionary history of atlas. The protein-coding portion of the gene likely arose at the base of the Drosophila genus on the X chromosome but was unlikely to be essential, as it was then lost in several independent lineages. Within the last ~15 million years, however, the gene moved to an autosome, where it fused with a conserved non-coding RNA and evolved a non-redundant role in male fertility. Altogether, this study provides insight into the integration of novel genes into biological processes, the links between genomic innovation and functional evolution, and the genetic control of a fundamental developmental process, gametogenesis.

Randomized Clinical Trial: Crofelemer Treatment in Women With Diarrhea-Predominant Irritable Bowel Syndrome.

INTRODUCTION: Crofelemer, the active compound purified from latex of Croton lechleri, has been shown to improve HIV and traveler's diarrhea and improve pain in women with irritable bowel syndrome-diarrhea (IBS-D). This trial evaluated the effect of crofelemer on abdominal pain in women with IBS-D. METHODS: Women with IBS-D were randomized to crofelemer (125 mg) or placebo twice daily for 12 weeks. The primary efficacy endpoint was overall change in percentage of abdominal pain/discomfort-free days. Post hoc analysis for Food and Drug Administration (FDA) monthly responders was performed for stool consistency, abdominal pain, and combined stool consistency and abdominal pain. RESULTS: A total of 240 women were enrolled. There was no significant difference in overall percentage of pain/discomfort-free day between the groups. In post hoc analysis, FDA abdominal pain monthly responders were significantly more likely during months 1 through 2 (58.3% vs 45.0%, P = 0.030) as well as during the entire 3 months (54.2% vs 42.5%, P = 0.037) in the crofelemer group when compared with placebo. However, there was no significant difference in the percentage of FDA stool consistency monthly responders or combined stool consistency and pain monthly responders between the groups. Crofelemer had a safety profile similar to placebo. DISCUSSION: Crofelemer did not significantly improve abdominal pain over placebo by the primary endpoint. However, it did based on the FDA abdominal pain monthly responder endpoint. This suggests that crofelemer may have a role in the treatment of abdominal pain associated with IBS-D. Further studies are warranted to evaluate the potential of crofelemer as a visceral analgesic.