The Sperm TRP-3 Channel Mediates the Onset of a Ca2+ Wave in the Fertilized C. elegans Oocyte

Publication date: Available online 7 April 2016
Source:Cell Reports
Author(s): Jun Takayama, Shuichi Onami
Sperm induce Ca²⁺ waves in the fertilized egg by introducing soluble factors or by surface interactions, which activate egg Ca²⁺ channels. Involvement of sperm Ca²⁺ channels is predicted by the conduit model; however, this model has not been validated. In Caenorhabditis elegans, the sperm-specific TRP family Ca²⁺ channel TRP-3 mediates sperm-oocyte fusion. Here, using high-speed in vivo imaging and image analyses, we show that sperm induce an immediate local Ca²⁺ rise followed by a Ca²⁺ wave in fertilized C. elegans oocytes. Oocytes fertilized by rare trp-3 escaper sperm showed a lack of local rise and a delay in onset of the Ca²⁺ wave. Sperm Ca²⁺ imaging suggests that the local rise is not due to the bolus introduction of stored Ca²⁺. These results suggest that, along with its primary function in sperm-oocyte fusion, TRP-3 induces Ca²⁺ waves in fertilized oocytes, consistent with the conduit model.

Graphical abstract

Teaser

Fertilization induces Ca²⁺ responses in the oocyte. By using high-speed in vivo imaging of fertilization in C. elegans, Takayama and Onami identified TRP-3 as a sperm Ca²⁺ channel required for the generation of a Ca²⁺ response in the fertilized oocyte.


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