Differentiation of the vitelline coat in the ascidianCiona intestinalis: an ultrastructural study

Cotelli, Franco; Andronico, Franca; Santis, Rosaria De; Monroy, Alberto; Rosati, Floriana

doi:10.1007/bf00848752

Cited by 36 publications

(24 citation statements)

References 14 publications

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“…This procedure breaks the VC, thus allowing the outflow of the oocyte material. The homogenate was then filtered through a G3 Buchner filter; the VC remains on the filter, and after several rinses with sea water it is essentially free of egg contaminants (13).…”

Section: Materlals and Methodsmentioning

confidence: 99%

“…In a previous study (13) we described the differentiation of the VC ofthe oocyte of Ciona intestinalis during oogenesis. We demonstrated that the precursor material of the VC (VCPM) of Ciona oocytes first appears soon after the oocyte and its accompanying cells have left the germinal strand and is in the form offluffy fibrillar patches at the surface of the oocyte.…”

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confidence: 99%

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Synthesis of fucosyl-containing glycoproteins of the vitelline coat in oocytes of Ciona intestinalis (Ascidia).

Rosati¹,

Cotelli²,

Santis³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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The sperm receptors of the ascidian oocyte are located at the outer surface of the vitelline coat (formerly called the chorion). The fucose residues are the receptor's most important components for sperm recognition and binding. We asked whether the fucosyl-containing glycoproteins of the vitelline coat are a product ofthe oocyte, the follicle cells, or the test cells. Ovaries of Ciona intestinalis were injected with L-[3H]fucose and the progress of its incorporation was followed by using autoradiography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis of the injected gonads and of the isolated vitelline coats. We found that incorporation of fucose begins within the vitellogenic oocytes, and fucose slowly accumulates in the differentiating vitelline coat. At no time could fucose incorporation be detected Experimental evidence obtained in several animals (1-7) indicates that the vitelline coat (VC) (and its equivalent zona pellucida in the mammalian egg) bears the primary sperm receptors-i. e., the molecular complexes that enable specific recognition and binding of spermatozoa to the egg. The VC is usually considered to be a product of the follicle cells. Should this be the case, it implies that the synthesis of the sperm receptors, which play a key role in the process of sperm-egg interaction, is delegated to the somatic components ofthe gonad.In mammals the primary sperm receptors are a component of the zona pellucida, which makes it analogous to the VC of, for example, the sea urchin egg. Recently, Bleil and Wassarman (8) have provided convincing evidence that the zona pellucida is synthesized by the oocyte.The ascidian egg is convenient for studying functional relationships between the oocyte and its envelopes. The latter consist ofa fibrous chorion and a layer oflarge follicle cells attached to its outer surface. Between the chorion and the surface of the oocyte there is a perivitelline space filled with the test cells, whose significance is still unclear. The chorion can be manually separated (with fine needles) from the egg. This offers an almost unique opportunity to study "naked" eggs and egg envelopes without the use of enzyme treatments. Work from this laboratory has shown that the chorion is the carrier of the primary sperm receptors (9, 10); hence, we have suggested that it be designated as the VC of the egg (11). There are no other membranes or coats at the surface of the egg (12).In a previous study (13) we described the differentiation of the VC ofthe oocyte of Ciona intestinalis during oogenesis. We demonstrated that the precursor material of the VC (VCPM) of Ciona oocytes first appears soon after the oocyte and its accompanying cells have left the germinal strand and is in the form offluffy fibrillar patches at the surface of the oocyte. When the oocyte enters the vitellogenic stage, the patches merge with one another, thus giving rise to a coat ofloosely arranged fibrils that surrounds the oocyte. At this stage a continuous layer, identifiable as the VC, becomes visible ev...

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Section: Materlals and Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Synthesis of fucosyl-containing glycoproteins of the vitelline coat in oocytes of Ciona intestinalis (Ascidia).

Rosati¹,

Cotelli²,

Santis³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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“…However, we do not know whether the CiLgals are components of the VC involved in the allorecognition mechanism responsible of the FC/VC-mediated self-incompatibility barrier established by the FCs against autologous sperms during the follicle maturation [50,51,72]. Our findings on the labeling of the VC layer may merely depend on the passive capture of galectins released from the FCs, as also shown by the labeling with CinPO2 riboprobe and antibody.…”

Section: Discussionmentioning

confidence: 70%

“…Nonetheless, evidence of incomplete reproductive isolation from the wild population within the shared range of A and B types, raises the taxonomic issue [57]. Based on the collection sites, most published reports on the oocytes and accessory cells derive from Type A animals [46,50,51,58,59], in addition, all our studies have been performed on specimens from the Mediterranean coasts. Therefore, waiting for the taxonomic status to be precisely defined, in the present paper the name C. intestinalis (Type A) is kept.…”

Section: Animalsmentioning

confidence: 99%

“…According to a transmission electron microscopy study by Mancuso [48], the C. intestinalis (type A) ovarian follicles at vitellogenic and post-vitellogenic stages are composed of two maternal accessory cell types which surround the oocytes: follicle cells (outer layer, FCs), and test cells (inner layer, TCs) which are in contact with the oocyte membrane. A thin acellular vitelline coat (VC) connects FCs and TCs [48,50]. In the growing follicle, the TCs become embedded in the outermost cytoplasm of the oocyte and form a dense layer [48,51].…”

Section: Introductionmentioning

confidence: 99%

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In the ovary of Ciona intestinalis (Type A), immune-related galectin and phenoloxidase genes are differentially expressed by the follicle accessory cells

Parrinello¹,

Sanfratello²,

Parisi³

et al. 2018

Fish & Shellfish Immunology

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A B S T R A C TRiboprobes (in situ hybridization) and antibodies (immunohistochemistry), previously used to show the upregulation of Ciona intestinalis (Type A) galectins (CiLgals-a, CiLgals-b) and phenoloxidase (CinPO2) immunerelated genes, were tested on histological sections of the ovary. The ovarian follicles are composed of oocytes encased by follicular cells (FCs) and test cells (TCs). Results show the transcription upregulation of both CiLgals and CinPO2 genes in the vitellogenic FCs, conversely distinct cytolocalization of the proteins are shown. At vitellogenic stage, the CiLgals are localized in the FCs, in the oocyte cytoplasm, and close to the germinal vesicle (GV), whereas the CinPO2 was never identified in the FCs. In a presumptive advanced phase and at the postvitellogenic stage the TCs appear to be labelled by the CinPO2 riboprobe, and the protein identified by the antibody suggesting an mRNA transcytosis process from FCs. At post-vitellogenic stage the CiLgals mainly enrich the GV nucleoplasm, whereas the CinPO2 is contained in TCs and in the ooplasm but never found in the GV. This finding sheds new light on a former paper in which TCs were reported to be the only CinPO2-producing cells in the ovarian follicle. Finally, CiLgals and CinPO2 genes transcription and proteins production seem to be associated with accessory cells during their differentiation from vitellogenic to post-vitellogenic stage. The present findings promote further research on the early upregulation of immune-related genes, and the potential multifunctional role of the produced proteins. In addition further insight on the accessory cells involvement in ascidian oogenesis are reported.

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Mechanism of the block to hybridization and selfing between the sympatric ascidiansCiona intestinalis andCiona savignyi

Byrd

Lambert

2000

Mol. Reprod. Dev.

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The solitary ascidians Ciona intestinalis and Ciona savignyi co‐occur in southern California harbors, but no hybrids have been recognized in nature. Numerous differences in their egg morphology were detected. Homologous (normal outcross) fertilization yielded 96–99% cleavage, where autologous (self) fertilization showed 3% and heterologous (hybrid) fertilization showed 0–1%. Acid treatment (pH 3.2) removed the block to selfing (P < 0.0001) but not hybridization for both species. Heterologous sperm bind to the vitelline coat (VC), but fail to penetrate. Enzymatic removal of the VC resulted in 91–97% cleavage with autologous and heterologous sperm (P < 0.0001). The vitelline coats of the two species differ in lectin binding to surface glycosides. Fertilization in both species is significantly inhibited by the lectins, fucose binding protein (P < 0.0001) and concanavalin A (P < 0.0001), and wheat germ agglutinin inhibits fertilization in C. intestinalis (P < 0.0001) but is without effect on C. savignyi fertilization. Self and hybrid blocks employ different mechanisms including glycoside composition and acid sensitivity. Mol. Reprod. Dev. 55:109–116, 2000. © 2000 Wiley‐Liss, Inc.

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Differentiation of the vitelline coat in the ascidianCiona intestinalis: an ultrastructural study

Cited by 36 publications

References 14 publications

Synthesis of fucosyl-containing glycoproteins of the vitelline coat in oocytes of Ciona intestinalis (Ascidia).

Synthesis of fucosyl-containing glycoproteins of the vitelline coat in oocytes of Ciona intestinalis (Ascidia).

In the ovary of Ciona intestinalis (Type A), immune-related galectin and phenoloxidase genes are differentially expressed by the follicle accessory cells

Mechanism of the block to hybridization and selfing between the sympatric ascidiansCiona intestinalis andCiona savignyi

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