. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ECDYSTEROID FEEDBACK ON MIH RELEASE 267 addition to ecdysone, an unknown, less polar, ecdysteroid (structural analysis is in progress); this unknown appears in quantities 5-fold greater than ecdysone but has an affinity for antiserum H-21B 100-fold less than ecdysone (Watson and Spaziani, 1985b). Thus, ecdysone levels that we report in the medium of MIH bioassay runs are un- derrepresented by well under an order of magnitude. Protein was quantified by the Bradford (1976) method. Statistics were done by Students Mest and all
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ECDYSTEROID FEEDBACK ON MIH RELEASE 267 addition to ecdysone, an unknown, less polar, ecdysteroid (structural analysis is in progress); this unknown appears in quantities 5-fold greater than ecdysone but has an affinity for antiserum H-21B 100-fold less than ecdysone (Watson and Spaziani, 1985b). Thus, ecdysone levels that we report in the medium of MIH bioassay runs are un- derrepresented by well under an order of magnitude. Protein was quantified by the Bradford (1976) method. Statistics were done by Students Mest and all values are expressed as mean and standard error of the mean (SEM). RESULTS Serum ecdysteroid tilers of crabs given injections of 45 jug of 20-hydroxyecdysone at 0-h and 18 h later were elevated 3- and 8-fold 18- and 24-h, respectively, after the initial injection (Fig. 1). Y-organectomy reduced hemolymph ecdysteroid levels over a 6-day period to 65% of levels in sham-operated controls (Fig. 2). Eyestalk ganglia removed from crabs with elevated ecdysteroid levels (24 h after initial 20-hydroxyec- dysone injection; cf. Fig. 1) released significantly less MIH activity during a 2-h in- cubation in saline than did control ganglia; ganglia-conditioned saline from controls inhibited basal Y-organ steroidogenesis by 42%, while that from crabs with elevated ecdysteroid tilers did not affecl ecdysleroid produclion significanlly (Fig. 3). Isolaled ganglia from Y-organeclomized animals wilh reduced ecdysleroid lilers (cf., Fig. 2) released MIH activily al levels similar lo ganglia from sham-operaled conlrols or from unoperaled conlrols (Y-organ sleroidogenesis was suppressed 40-50%; Fig. 3). Exlracls of eyeslalk ganglia from Ihe ecdysleroid-lreated crabs contained significantly more MIH activily lhan ganglia exlracls from conlrol crabs (Fig. 4); Y-organ sleroidogenesis was inhibiled 65% and 80% by exlracls from conlrol and 20-hydroxyecdysone-injecled crabs, respeclively. Figure 4 also show
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
