. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0-0. 0 STRENGTH OF CORAL INDUCER Figure 7. Frequency of metamorphosis of larvae of Phesrilla sibogae after 24-h exposure to varying dilutions of coral inducer, following treatment with 5 x 10~7 M (squares) or 10~5 M (triangles) L-DOPA, or MBL-artificial seawater control (circles) on day 6 (A), 7 (B). 8 (C), or9(D, control only) postfertilization. Each point represents the mean (±1 SEM) of 5 replicate trials of 10~5 M L-DOPA and MBL. or 4 trials for 5 x 10"7 M L-DOPA. Asterisks indicate signific
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0-0. 0 STRENGTH OF CORAL INDUCER Figure 7. Frequency of metamorphosis of larvae of Phesrilla sibogae after 24-h exposure to varying dilutions of coral inducer, following treatment with 5 x 10~7 M (squares) or 10~5 M (triangles) L-DOPA, or MBL-artificial seawater control (circles) on day 6 (A), 7 (B). 8 (C), or9(D, control only) postfertilization. Each point represents the mean (±1 SEM) of 5 replicate trials of 10~5 M L-DOPA and MBL. or 4 trials for 5 x 10"7 M L-DOPA. Asterisks indicate significant difference (*,P< ; **, P < ) from MBL artificial seawater control at a given dilution of coral inducer. response to CI even in the continued presence of a-MMT. Larvae that received this combined treatment of L-DOPA and a-MMT had levels of DA and NE that were higher than those of MBL-ASW controls but lower than those measured in larvae treated with L-DOPA only. The mechanism by which a-MMT depletes endogenous DA. at least in mam- malian nervous systems, involves both inhibition of tyrosine hydroxylase activity by a-MMT and displacement of stored DA by a decarboxylated metabolite of a-MMT (Uretsky et al., 1975; Bernabe et ai. 1996). The latter mechanism may help explain why larvae treated with both a-MMT and contained less DA and NE than those treated with i-DOPA alone. Taken together, our manipulations of cate- cholamine biosynthesis with L-DOPA and a-MMT in com- petent larvae show that depletion of endogenous cat- echolamines is accompanied by inhibition of Cl-induced metamorphosis, whereas enhancement of catecholamines is accompanied by potentiation of metamorphic responses to CI. Thus catecholamines appear to serve as endogenous modulators of metamorphosis in competent larvae of P. sibogae. Catecholamine-containing cells in competent larvae were labeled by FaGlu histochemistry (Fig. 4) in order to map locations of these putative modulators of metamo
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
