VASA-induced cytoplasmic localization of CYTB-positive mitochondrial substance occurs by destructive and nondestructive mitochondrial effusion, respectively, in early and late spermatogenic cells of the Manila clam.

To analyze the release of mitochondrial material, a process that is believed to be (i) induced by the VASA protein derived from germplasm granules, and (ii) which appears to play an important role during meiotic differentiation, the localization of the CYTB protein was studied in the process of spermatogenesis of the bivalve mollusk Ruditapes philippinarum (Manila clam). It was found that in early spermatogenic cells, such as spermatogonia and spermatocytes, the CYTB protein shows dispersion in the cytoplasm following the total disaggregation of VASA-invaded mitochondria, what is called here as "destructive mitochondrial effusion (DME)." It was found that the mitochondria of the maturing sperm cells also uptake VASA. It is accompanied by extramitochondrial transmembrane localization of CYTB assuming mitochondrial content release without mitochondrion demolishing. This phenomenon is called here as "nondestructive mitochondrial effusion (NDME)." Thus, in the spermatogenesis of the Manila clam, two patterns of mitochondrial release, DME and NDME, were found, which function, respectively, in early spermatogenic cells and in maturing spermatozoa. Despite the morphological difference, it is assumed that both DME and NDME have a similar functional nature. In both cases, the intramitochondrial localization of VASA coincides with the extramitochondrial localization of the mitochondrial matrix.

Modulation of Mytilus trossulus (Bivalvia: Mollusca) larval survival and growth in culture. Short communication.

Commercial importance and ability to live in a wide range of salinities have made the common mussel, Mytilus trossulus, a relevant model to study modulation of larval growth and development. We investigated the effects of various salinities combined with neomycin and ampicillin application on Mytilus larvae survival and growth. Both neomycin and ampicillin enhanced trochophore and veliger survival under condition of low salinity. The average veliger size was increasing in accordance with the increase of salinity. In case of neomycin treatment 3.6% of the larvae reached the pediveliger stage. No abnormalities of larval morphology of the FMRFamide and 5-HT systems occurred after 7 days of culturing with both antibiotics.