Calcium-regulated Fusion of Yolk Granules is Important for Yolk Degradation During Early Embryogenesis of Rhodnius Prolixus Stahl.
From: Laboratório de Entomologia Médica, Instituto de Biofísica Carlos Chagas Filho (IBCCF), Universidade Federal do Rio de Janeiro (UFRJ), Cidade Universitária — Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brasil.
The Journal of experimental biology
- Publish Date: Jan 2007
- ISSN: 0022-0949
- Volume: 210
- Issue: Pt 1
- Pages: 138-48
- Medium: Print
- Language: English
- Citation (JAMA): Ramos I B, Miranda K, de Souza W, et al. Calcium-regulated Fusion of Yolk Granules is Important for Yolk Degradation During Early Embryogenesis of Rhodnius Prolixus Stahl.. J. Exp. Biol. Jan 2007;210:138-48
Abstract
This study examined the process of membrane fusion of yolk granules (YGs) during early embryogenesis of Rhodnius prolixus. We show that eggs collected at days 0 and 3 after oviposition contain different populations of YGs, for example day-3 eggs are enriched in large YGs (LYGs). Day-3 eggs also contain the highest free [Ca(2+)] during early embryogenesis of this insect. In vitro incubations of day-0 YGs with [Ca(2+)] similar to those found in day-3 eggs resulted in the formation of LYGs, as observed in vivo. Fractionation of LYGs and small YGs (SYGs) and their subsequent incubation with the fluorescent membrane marker PKH67 showed a calcium-dependent transference of fluorescence from SYGs to LYGs, possibly as the result of membrane fusion. Acid phosphatase and H(+)-PPase activities were remarkably increased in day-3 LYGs and in calcium-treated day-0 LYGs. Both fractions were found to contain vitellins as major components, and incubation of YGs with calcium induced yolk proteolysis in vitro. Altogether, our results suggest that calcium-induced membrane fusion events take part in yolk degradation, leading to the assembly of the yolk mobilization machinery.
Mesh Headings (Keywords): Animals, Calcium, Egg Proteins, Embryo, Nonmammalian, Embryonic Development, Hydrolases, Intracellular Membranes, Ovum, Proton Pumps, Rhodnius, Vitellins
Check for Full Text / PubMed Unique Identifier (PMID): 17170157
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