Mononuclear muscle cells in Drosophila ovaries revealed by GFP protein traps

Abstract

Genetic analysis of muscle specification, formation and function in model systems has provided valuable insight into human muscle physiology and disease. Studies in Drosophila have been particularly useful for discovering key genes involved in muscle specification, myoblast fusion, and sarcomere organization. The muscles of the Drosophila female reproductive system have received little attention despite extensive work on oogenesis. We have used newly available GFP protein trap lines to characterize of ovarian muscle morphology and sarcomere organization. The muscle cells surrounding the oviducts are multinuclear with highly organized sarcomeres typical of somatic muscles. In contrast, the two muscle layers of the ovary, which are derived from gonadal mesoderm, have a mesh-like morphology similar to gut visceral muscle. Protein traps in the Fasciclin 3 gene produced Fas3::GFP that localized in dots around the periphery of epithelial sheath cells, the muscle surrounding ovarioles. Surprisingly, the epithelial sheath cells each contain a single nucleus, indicating these cells do not undergo myoblast fusion during development. Consistent with this observation, we were able to use the Flp/FRT system to efficiently generate genetic mosaics in the epithelial sheath, suggesting these cells provide a new opportunity for clonal analysis of adult striated muscle.

Influence of ovarian muscle contraction and oocyte growth on egg chamber elongation in Drosophila

“…Mef2-Gal4 is expressed in the muscle sheath, but not the follicle cells (Fig. 2D,D′) (Hudson et al, 2008). Expressing wb-RNAi-a with this driver decreases the egg's aspect ratio (Fig.…”

“…There are two muscle types in the ovary proper: (1) the epithelial sheath, a tube of muscle that surrounds each ovariole, and (2) the peritoneal sheath, a thin meshwork that surrounds the entire ovary (Hudson et al, 2008). We focus on the epithelial sheath, but will refer to this tissue as the 'muscle sheath' to avoid confusion with the follicular epithelial cells.…”

Female-biased dimorphism underlies a female-specific role for post-embryonic Ilp7 neurons inDrosophilafertility

“…Egg laying in females is under tight neuronal control and its regulatory circuitry is one of the best understood female behaviors (Middleton et al, 2006;Rodríguez-Valentín et al, 2006;Yapici et al, 2008;Yang et al, 2009;Rezával et al, 2012). After eggs exit the ovary, they are propelled through the oviduct by somatic-like muscles that ring the oviduct (Hudson et al, 2008). Peristaltic contraction/relaxation activity of these muscles is directed by unidentified excitatory glutamatergic motoneurons and inhibitory octopaminergic neurons (Middleton et al, 2006;Rodríguez-Valentín et al, 2006;Kapelnikov et al, 2008).…”

A novel Cre/loxP system for mosaic gene expression in the Drosophila embryo

“…This finding indicates that the efficiency of Gal4 induction can differ greatly among tissues or organs. The FLP/FRT system, which involves trans-recombination, relies on mononuclear cells (Hudson et al, 2008). However, our system induces mosaics via cis-recombination.…”