. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 254 Y. K. MARUYAMA 100-i Q 50- PQ ID 0-. 7 I I 100 0,001 1 10 CONCENTRATION OF RADIAL NERVE HOMOGENATE (mg/rnl) FIGURE 2. Effects of radial nerve homogenate on induction of oocyte maturation in ovarian fragments of H. leucospilota. Oocytes extruded from the ovarian fragment (open circles) and those remaining within the ovarian fragment (closed circles) were observed simultaneously. Each point represents mean ± SE of five experiments. In subthreshold concentrations, a low percentage of oocytes located at the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 254 Y. K. MARUYAMA 100-i Q 50- PQ ID 0-. 7 I I 100 0,001 1 10 CONCENTRATION OF RADIAL NERVE HOMOGENATE (mg/rnl) FIGURE 2. Effects of radial nerve homogenate on induction of oocyte maturation in ovarian fragments of H. leucospilota. Oocytes extruded from the ovarian fragment (open circles) and those remaining within the ovarian fragment (closed circles) were observed simultaneously. Each point represents mean ± SE of five experiments. In subthreshold concentrations, a low percentage of oocytes located at the cut-ends of the fragment showed GVBD. There was a range (1-5 mg/ml) of concentrations of radial nerve homogenates where spawning (and subsequent maturation of the spawned oocytes) occurs but GVBD rates of oocytes remaining in the fragment are very low (Fig. 2). The curve indicates that a 10-fold higher concentration is required for GVBD in unextruded oocytes. Nearly all the oocytes remaining in ovarian fragments were induced to mature at a concentration of 5-10 mg/ml. Similar results were observed in other sea cucumbers (Fig. 3A, Table II). A very high concentration (400 mg/ml) of radial nerve homogenate from H. leucospilota also successfully induced maturation of all oocytes and spawning in ovarian fragments of H. leucospilota and H. pardalis. These results show that the radial nerve has a factor(s) responsible for spawning and oocyte maturation. Radial nerve homogenates (or extracts) were then applied to isolated oocytes with or without follicle cells (see Figs. ID, 5A). In H. leucospilota, most (83 ± 8%, n = 3) of the isolated oocytes with follicle cells were induced to mature by 1 or 5 mg/ml of radial nerve homogenate. By contrast, none of follicle cell-free oocytes were induced to mature by the homogenate at a wide range of concentration ( 50 mg/ml) (n = 3) ( Fig. 5D). In control sea water, no GVBD was observed in oocytes with or without follicle cells. In H.
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
