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J Cell Biol. 2012 Sep 17;198(6):1075-91. doi: 10.1083/jcb.201204024.

Temporal sampling, resetting, and adaptation orchestrate gradient sensing in sperm.

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  • 1Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, 53175 Bonn, Germany.

Abstract

Sperm, navigating in a chemical gradient, are exposed to a periodic stream of chemoattractant molecules. The periodic stimulation entrains Ca(2+) oscillations that control looping steering responses. It is not known how sperm sample chemoattractant molecules during periodic stimulation and adjust their sensitivity. We report that sea urchin sperm sampled molecules for 0.2-0.6 s before a Ca(2+) response was produced. Additional molecules delivered during a Ca(2+) response reset the cell by causing a pronounced Ca(2+) drop that terminated the response; this reset was followed by a new Ca(2+) rise. After stimulation, sperm adapted their sensitivity following the Weber-Fechner law. Taking into account the single-molecule sensitivity, we estimate that sperm can register a minimal gradient of 0.8 fM/µm and be attracted from as far away as 4.7 mm. Many microorganisms sense stimulus gradients along periodic paths to translate a spatial distribution of the stimulus into a temporal pattern of the cell response. Orchestration of temporal sampling, resetting, and adaptation might control gradient sensing in such organisms as well.

PMID:
22986497
PMCID:
PMC3444779
DOI:
10.1083/jcb.201204024
[PubMed - indexed for MEDLINE]
Free PMC Article
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