Development of irradiated tunicate buds: Is cell division cycle required for morphallaxis?

In the tunicate, Polyandrocarpa misakiensis, transdifferentiation occurs in the multipotent atrial epithelium during morphallactic bud development. Irradiation (10-80 Gy) or aphidicolin (10 μg/mL) blocked this process severely, although the atrial epithelium could form organ placodes. The placodes consisted of cuboidal cells with a high nucleus : cytoplasm ratio and were lacking the alkaline phosphatase antigen from the cell surface, suggesting that the atrial epithelium might undergo dedifferentiation without initiating cell cycling.

Self-Nonself Recognition Activity Extracted from Self-Sterile Eggs of the Ascidian, Ciona intestinalis: (ascidian/fertilization/allo-recognition/acid extract/HPLC).

Eggs of the hermaphrodite, self-sterile ascidian, Ciona intestinalis, were washed with acid seawater (pH 3.2), and the washing solution was then adjusted to pH 8.2.

Concanavalin A Modifies Allo-specific Sperm-Egg Interactions in the Ascidian, Ciona intestinalis: (self incompatibility/vitelline coat/concanavalin A/Ciona gametes).

In the self sterile ascidian, Ciona intestinalis, the spermatozoa rarely bind to the vitelline coat of autologous eggs and never penetrate it. We report here that concanavalin A (ConA), a lectin recognizing mannose or glucose residues of carbohydrates, can modify these self- and nonself-specific sperm-egg interactions. When eggs were pretreated with 0.

Helper Function of Follicle Cells in Sperm-Egg Interactions of the Ascidian, Ciona intestinalis: (Ciona gametes/fertilization/follicle cells/soy bean agglutinin/DAPI).

Studies were made on the involvement in sperm-egg interactions of follicle cells of Ciona intestinalis, which are tall, vacuolated cells attached to the outer surface of the egg vitelline coat. The basal surface of the follicle cells is polygonal. The borders between cells could easily be observed by the binding of fluorescent SBA (soy bean agglutinin), a lectin recognizing N-acetylgalactosamine (GaINAc) residues.

Cytological Characterization of Self Incompatibility in Gametes of the Ascidian, Ciona intestinalis: (Ciona gametes/self incompatibility/egg water/sperm-vitelline coat interaction/DAPI staining).

We have determined how many elements are involved in the regulation of self-fertilization in the solitary ascidian, Ciona intestinalis that is an incompletely self-sterile species. Animals collected in the field were repeatedly induced to spawn in order to examine their selfing ratios. About 20% of them were self-fertile, although the ratios fluctuated considerably among respective spawnings.

DEVELOPMENT OF SPATIAL ORGANIZATION IN PALLEAL BUDS OF THE COMPOUND ASCIDIAN, SYMPLEGMA REPTANS.

The continuous observation of living animals and the reconstruction of serial sections of fixed specimens have revealed 15 developmental stages and their timetable in palleal buds of the compound ascidian, Symplegma reptans. The bud primordium (stage 1) appeared on the right anterior region of the atrial epithelium of its parental bud (stage 9). It evaginated to form a vesicle along with the epidermis (stage 3) about two days later (at 18°C).