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#chemotaxis

2 public questions tagged with this topic.

Sea urchin -l

Sea urchin eggs attract sperm via:

Broadcast spawning sea urchins release gametes freely into seawater where sperm must locate relatively immobile eggs efficiently to ensure reproductive success. Egg jelly coat surrounding oocyte releases species-specific peptides that diffuse forming stable chemical gradient extending millimeters. Spermatozoa sense gradient concentration via receptor guanylate cyclase and CatSper Ca2+ channels, adjusting flagellar waveform asymmetry to bias swimming up gradient, classic chemotaxis analogous to bacterial navigation. Electrical signals, temperature gradients or light cues are not directional gui

Ref: Kaupp et al., Annu Rev Physiol, Chemotaxis in sea urchin sperm; Gilbert Chapter 7: Egg jelly chemotaxis.

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Fertilization in mammals-l

Progesterone attracts sperm via:

Gradients of progesterone secreted by cumulus cells surrounding ovulated oocyte attract capacitated sperm via chemotaxis. Cumulus-derived nanomolar to micromolar progesterone is detected by sperm membrane hydrolase ABHD2 that degrades 2-arachidonoylglycerol, relieving inhibition of CatSper calcium channel, producing chemotactic calcium transients steering flagellar bending toward source. Experimental microfluidic assays show accumulation of human sperm toward progesterone sources. This chemical attraction operates at short range close to oocyte, refining navigation after long-range thermotaxis

Ref: Publicover et al., Nature 2008: Progesterone via ABHD2 and CatSper mediates sperm chemotaxis near cumulus.

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