ISSN:
0148-7280
Keywords:
sprem
;
mitochondrion
;
calcium
;
calmodulin
;
actin
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
The ascidian sperm reaction, Which involves swelling, migration, and loss of the single large mitochondrion, can be triggered in vitro by raising the seawater pH to 9.3 or lowering Na+ to 20 mM, but only if the sperm are allowed to attach to a suitable Substate. Mitochondrial translocation does not usually occur in the absence of sperm attachment. Extracellular Ca2+ is necessary for triggering the reaction with low Na+ but not high pH; however, the intrecellular Ca2+ blocker, TMB-8, inhibits high pH-induced mitochondrial movement in the absence of extracellular Ca2+. After swelling, the mitochondrion fluoresces in the presence of chlortetracycline, suggesting that Ca2+ becomes membranebound after activation. Elevated cAMP and theophylline both inhibit mitochondrial move ment but not sperm motility. The antiactin drug cytochalasin B(10μM) and the calmodulinblocking drugs TFP (1 μM) and W-13 (10 μM) block mitochondrial movement, suggesting roles for actin and calmodulin in mitochondrial movement. A model is proposed relating intracellular alkalinization, Ca2+ influx, actin, myosin, and calmodulin in mitochondrial translocation.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrd.1120080309
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