Molecular Mechanisms underlying Allo-recoguition in Ascidians

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The contact reaction of hemocytes and self-sterility of gametes are typical examples of all-recognition in the ascidians We have found in Halocymhia roreizi that the contact reaction is accompanied with a burst of oxygen consumption by phenol oxidase. Basing upon this finding, we developed a method to quantify the contact reaction Similar bursts were observed when hemocytes were mixed eggs or follicle cells from different individuals.Sperm binding to the vitelline coat is a step of allo- recognition in Ciona imtesinalis. Although H.roreizi is strictly self-stcrile, autologous as well as homologous spem bound to the vitelline coat. However, autologous sperm did not block fertilozation by homologous sperm at all, suggesting that binding of autologous sperm is phusiologically meaningless for fertilization. A highly hydrophobic glycoprotein of 70 kDa isolated from H.roretzi vitcllinc coats was purificd as a sperm-receptor. Thc N-terminal eicosapeptide and four other fragments (sixty residues in total)of this protein were sequenced.In order to answer a question whether self-sterility is purely genetic or it depends to some extent on a kind of clonal selection during devclopment, 8-ccll embryos of C.intestinalis were dissected into left and right halves to make chimeric chimeric embryos. No sexually matured chimeras were so for obtained.