Spawning was detected visually by sperm and egg release.
To establish post-sex clones, sexually-produced diapausing eggs were collected from females upon egg release.
Root exudates often attract nematodes and trigger egg hatching in certain plant-parasitic nematode species [ 31].
For instance, a study at the University of Birmingham in the UK has uncovered that "prior to fertilization, a cloud of cumulus cells surrounding the egg releases progesterone, the female sex hormone, triggering a calcium influx into the sperm... Progesterone has also been implicated in providing a chemical gradient by which sperm can navigate toward the egg".
Thapsigargin and BAPTA [bis- o-aminophenoxy)ethane- N, N, N′, N′-tetra-acetic acid] were added to the Ca2+-free medium containing the eggs to trigger Ca2+ release that was detected with fura 2 dextran fluorescence at 380 nm wavelength [bis- o-aminophenoxy
The critical level of PLCζ protein required to trigger Ca2+ release in mouse eggs is approximately 10 50 fg, which is similar to the estimated levels in a single mouse sperm [ 1].
The environmental factor that triggers the release of eggs and sperm has not yet been established with certainty, but, at least in a few species, after one individual has shed its sex products, the others follow in a kind of chain reaction that is clearly chemical in nature.
Actual spawning occurs when a collection of males gather around gravid females, and begin writhing, twisting, bumping into and slithering over the tops of females, an activity which triggers the release of eggs.
In starfish eggs, studies using inhibitors designed against vertebrate proteins have shown that this Ca2+ rise requires an egg Src family kinase (SFK) that directly or indirectly activates phospholipase C-γ (PLC-γ) to produce IP3, which triggers Ca2+ release from the egg's endoplasmic reticulum (ER) [reviewed in Semin. Cell Dev. Biol. 12 (2001) 45].
And how does a message trigger oxytocin release?
"For example, there are many other ways to trigger the release of the molecule from the wires: photo release, chemical release, temperature release.
