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

Abstract

Organs are formed from multiple cell types that make distinct contributions to their shape. The Drosophila egg chamber provides a tractable model to dissect such contributions during morphogenesis. Egg chambers consist of 16 germ cells (GCs) surrounded by a somatic epithelium. Initially spherical, these structures elongate as they mature. This morphogenesis is thought to occur through a 'molecular corset' mechanism, whereby structural elements within the epithelium become circumferentially organized perpendicular to the elongation axis and resist the expansive growth of the GCs to promote elongation. Whether this epithelial organization provides the hypothesized constraining force has been difficult to discern, however, and a role for GC growth has not been demonstrated. Here, we provide evidence for this mechanism by altering the contractile activity of the tubular muscle sheath that surrounds developing egg chambers. Muscle hypo-contraction indirectly reduces GC growth and shortens the egg, which demonstrates the necessity of GC growth for elongation. Conversely, muscle hyper-contraction enhances the elongation program. Although this is an abnormal function for this muscle, this observation suggests that a corset-like force from the egg chamber's exterior could promote its lengthening. These findings highlight how physical contributions from several cell types are integrated to shape an organ.

The genetics of egg retention and fertilization success inDrosophila: One step closer to understanding the transition from facultative to obligate viviparity

“…Variants in another protein coding gene, LanB2 , a laminin protein, were also associated with egg retention ( P = 3.75 × 10 –6 ). Laminins have been found to be necessary for tissue morphogenesis (reviewed in Miner and Yurchenco ) and function in developmental processes such as egg chamber elongation, egg shape determination (Andersen and Horne‐Badovinac ), cell migration, induction, and maintenance of cell polarity (Diaz de la Loza et al. ) and glial cell development (Yu et al.…”

Laminin Levels Regulate Tissue Migration and Anterior-Posterior Polarity during Egg Morphogenesis in Drosophila

“…To this end, we measured the length/width ratio of control eggs, which, in agreement with published data, we found to be ∼2.75 (Markow et al., 2009; but see Andersen and Horne-Badovinac, 2016). Mutant eggs laid by laminin hypomorphic females did not show any significant differences in length/width ratio compared with control samples (Figures 5A and 5B).…”

A hormonal cue promotes timely follicle cell migration by modulating transcription profiles

“…Most genes we assayed are putative targets of both EcR and Tai. However, Hr4 and two known egg-development genes ( palisade, Yp3 )(Andersen and Horne-Badovinac, 2016; Fakhouri et al, 2006) were only identified in the EcR microarrays. In contrast, Fer1HCH , Neprilysin 2 , and CG14834 were only identified as potential Tai targets.…”