AI Article Synopsis

Article Abstract

Mature oocytes of the annelidan worm Pseudopotamilla occelata have a wide perivitelline space between the oocyte surface and the vitelline envelope and are arrested at the first metaphase (MI). We found a novel two-step Ca2+ increase in normally fertilized oocytes. The first Ca2+ increase originated at a cortex situated underneath a fertilizing sperm on the vitelline envelope, but failed to propagate beyond the center of the oocyte. The first localized Ca2+ increase was then followed by a larger Ca2+ increase starting from the whole oocyte cortex and spreading inwardly to the center. The first localized Ca2+ increase at fertilization was suppressed by the phospholipase C inhibitor U73122, and a similar Ca2+ change was induced by inositol 1,4,5-trisphosphate (IP3). On the other hand, the second global Ca2+ increase in fertilized oocytes was blocked by removal of external Ca2+ or the voltage-gated Ca2+ channel blocker D-600, and a similar Ca2+ change could be mimicked by addition of excess K+ only when external Ca2+ was present. These results suggest that the first localized Ca2+ increase and the second global Ca2+ increase at fertilization are regulated by Ca2+ release from IP3-sensitive stores and Ca2+ influx via voltage-gated Ca2+ channels, respectively. Our data also demonstrated that the localized Ca2+ increase induces the formation of large cytoplasmic protrusion, which helps the fertilizing sperm to enter the oocyte, whereas the following global Ca2+ increase is a prerequisite for the retraction of the cytoplasmic protrusion and the resumption of meiosis from MI.

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1440-169X.2008.01022.xDOI Listing

Publication Analysis

Top Keywords

ca2+ increase
44
ca2+
19
localized ca2+
16
global ca2+
12
increase
11
novel two-step
8
two-step ca2+
8
oocytes annelidan
8
annelidan worm
8
worm pseudopotamilla
8

Similar Publications

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!