Distribution and Migration of Immature Germ Cells in the Pearl OysterPinctada fucatawith the Expression Pattern of theVasaOrtholog byIn situHybridization

Sano, Natsumi; Kimata, Shunsuke; Obata, Masahiro; Komaru, Akira

doi:10.2983/035.034.0309

Cited by 6 publications

(1 citation statement)

References 13 publications

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“…7 ). In Mytilus (Obata et al 2010 ) and oysters (Sano et al 2015 ), for example, vasa transcripts were detected with a low signal also during the spent season in the area in which the gonad forms.…”

Section: Discussionmentioning

confidence: 99%

VASA expression suggests shared germ line dynamics in bivalve molluscs

Milani

Pecci

Ghiselli

et al. 2017

Histochem Cell Biol

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Germ line segregation can occur during embryogenesis or after embryogenesis completion, with multipotent cells able to give rise to both germ and somatic cells in the developing juvenile or even in adulthood. These undifferentiated cells, in some animals, are self-renewing stem cells. In all these cell lineages, the same set of genes, among which vasa, appears to be expressed. We traced VASA expression during the peculiar gonad rebuilding of bivalves to verify its presence from undifferentiated germ cells to mature gametes in an animal taxon in which the mechanism of germ line establishment is still under investigation. We utilized antibodies produced against VASPH, VASA homolog of Ruditapes philippinarum (Subclass Heterodonta), to compare the known expression pattern of R. philippinarum to two species of the Subclass Pteriomorphia, Anadara kagoshimensis and Crassostrea gigas, and another species of the Subclass Heterodonta, Mya arenaria. The immunohistological data obtained support a conserved mechanism of proliferation of “primordial stem cells” among the simple columnar epithelium of the gut, as well as in the connective tissue, contributing to the seasonal gonad reconstitution. Given the taxonomic separation of the analyzed species, we suggest that the process could be shared in bivalve molluscs. The presence of germ cell precursors in the gut epithelium appears to be a feature in common with model organisms, such as mouse, fruit fly, and human. Thus, the comparative study of germ line establishment can add details on bivalve development, but can also help to clarify the role that VASA plays during germ cell specification.Electronic supplementary materialThe online version of this article (doi:10.1007/s00418-017-1560-x) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

VASA expression suggests shared germ line dynamics in bivalve molluscs

Milani

Pecci

Ghiselli

et al. 2017

Histochem Cell Biol

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Germ cell line during the seasonal sexual rest of clams: finding niches of cells for gonad renewal

Milani

Pecci

Ghiselli

et al. 2017

Histochem Cell Biol

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Reconstitution and renewal of tissues are key topics in developmental biology. In this brief work, we analyzed the wintry spent phase of the reproductive cycle in the Manila clam Ruditapes philippinarum (Bivalvia, Veneridae) in order to study the gonad rebuilding that in this species occurs at the beginning of the warmer months. We labeled VASA homolog protein-a germ cell marker-and compared the histological observations of the spent phase with those of the previously analyzed gametogenic phase. In R. philippinarum, during the reproductive season, most of the body mass is represented by sack-like structures (acini) full of developing gametes. In that period, VASA-stained cells are present at the basal pole of the gut epithelium, in the connective tissue, and around the acini. We here show that during the spent phase large portions of the intestine lack such cell type, except for some areas showing a few faintly VASA-stained cells. Cells with similar nuclear morphology are present among loosely organized cells of connective tissue, sometimes as single units, sometimes in small groups, rarely partially organized in primordial gonadic structures. These observations match the findings of RNA-targeting studies that during the spent phase identified the source of bivalve germ cells within the connective tissue in the form of quiescent units and add new information on the possible maintenance of VASA-stained, multipotent cells among the batiprismatic cells of the intestine during the whole life span of these bivalves.

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