Reactive F-actin dynamics prevents cell penetration and maintains the activated sperm within the cyst enclosure until release

Date

Mar 12, 2015

Time

2:00 PM - 3:00 PM

Speaker

Krishanu Ray

Affiliation

Tata Institute of Fundamental Research, Department of Biological Sciences, Mumbai, India

Language

en

Main Topic

Biologie

Other Topics

Biologie

Host

Elisabeth Knust

Description

Sperm development and differentiation occurs within a somatic cell enclosure. Sperm release after maturation is a carefully regulated quality control filter, which maintains male fecundity. Drosophila melanogaster produces exceptionally long (1.87 mm) and thin sperm requiring a carefully calibrated mechanism to manage the passage into the seminal vesicle. Observation of sperm release in living testis indicated that it is a passive process. A bundle of sixty-four mature spermatids coil up inside an enclosure formed by two somatic cyst cells before release. Subsequently, the tails breach the enclosure and get sucked into the testicular duct, and then the rest of the bundle is pulled out of the head cyst cell (HCC) enclosure. The sperm heads also exert strong protrusive force, sufficient to puncture a cell, onto HCC. A novel form of localized and reactive F-actin dynamics balances this force. An actomyosin structure, enveloping the sperm heads inside the HCC acts as a boundary sensor, and a comet-like dynamic F-actin assembly generates strong localized force to push back every intrusion beyond this limit. These results provide a unique example of force-induced F-actin polymerization acting as active molecular shield at the plasma membrane.

Last modified: Mar 13, 2015, 9:04:07 AM