摘要:

AbstractThe lophotoxin analogue, bipinnatin‐B, is a potent neurotoxin isolated from the gorgonian coralPseudopterogorgia bipinnata. When tested on the cell body of an identified motor neurone, the fast coxal depressor motor neurone (Df) in the cockroach metathoracic ganglion, bipinnatin‐B, at concentrations of 10 μM, partially blocked nicotine‐induced depolarization. Blockade of the response to nicotine was almost complete at 30 μM bipinnatin‐B, and was partially reversible on rebathing the preparation in normal saline. Responses of the same neurone to GABA were unaffected by 30 μM bipinnatin‐B. © 1993 Wi

ISSN:0739-4462    

DOI:10.1002/arch.940230402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractNeosurugatoxin (NSTX), a neurotoxin isolated from the Japanese ivory molluscBabylonia japonica, is a potent neuronal nicotinic acetylcholine receptor (nAChR) antagonist. Hitherto, NSTX has been found to block only neuronal nAChRs that are insensitive to α‐Bgt. Here, we report for the first time that NSTX blocks an α‐Bgt‐sensitive nAChR on an identified insect motor neurone. Bath‐applied NSTX at a concentration of 10 nM and above reversibly blocks the nicotine‐induced depolarizations recorded from the cockroach(Periplaneta americana)fast coxal depressor motor neurone (Df) and is without effect on GABA‐induced responses detected on the same cell. NSTX is among the most potent blockers tested to date on nAChRs of motor neurone Df. © 1993 W

ISSN:0739-4462    

DOI:10.1002/arch.940230403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA defense mechanism in the cuticle of developingC. capitatawas demonstrated using an in vitro system consisting of isolated cuticular tyrosinase fromC. capitata, cuticular tyrosinase‐free proteins, tyrosine, andE. coli. The simultaneous presence of the above components resulted in the formation of large immobilizedE. coliaggregates. By contrast, omission of any of the above components failed to produce such aggregates. In other words,E. coliretained their mobility and viability. The results indicate that certain cuticular proteins are responsible for the nonself‐recognition, since they are able to bind to theE. colisurface in vitro, and a reactive tyrosine derivative is generated by the action of cuticular tyrosinase for the immobilization and probably killing ofE. coli. Based on these studies the most likely explanation for the nonself‐recognition and immobilization and/or killing of bacteria is the production ofE. coli‐protein complexes and their crosslinking through quinone intermediate. © 1993 Wiley

ISSN:0739-4462    

DOI:10.1002/arch.940230404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractEcdysone was found to be the major secreted steroid of ring glands dissected from blowfly larvae and incubated in vitro. Other secretory products such as 3‐dehydroecdysone and 20‐deoxy‐makisterone A could not be detected when the glands were labelled with tritiated cholesterol. Ecdysone synthesis and secretion were found to be tightly coupled. The highest rate of secretion was observed a few hours before pupariation. In vitro, the rate of ecdysone secretion by ring glands was affected significantly by coincubation with the central nervous system (CNS). Modulating effects from the CNS to the gland were mediated both by culture medium and by nerve connections. Distinct parts of the CNS revealed multiple and partially opposite effects on ecdysone secretion, suggesting a more complex control than had been anticipated. Multiple neural control systems appear to be involved. Moreover, the observed effects changed with development during the second half of the third instar, reflecting a significant plasticity of neural control. © 1993 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/arch.940230405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe activities of ecdysone oxidase (EO), 3‐oxoecdysteroid 3α‐reductase (3α‐R), and 3‐oxoecdysteroid 3β‐reductase (3β‐R) were determined for epidermis, hemolymph, and fat body of wandering fifth instarManduca sextalarvae and for midguts of various developmental stages between 3 days after the last larval and 14 days after the pupal ecdysis. The larval midgut was the only organ showing substantial specific activities of EO and 3α‐R, and both increased up to the seventh day after ecdysis. Hemolymph and fat body had only moderate to high 3β‐R and low EO activites, and the epidermis did not contain significant activity of any of the enzymes. On the ninth day after the last larval ecdysis the larval midgut epithelium was replaced by a new pupal midgut epithelium. After this event only 3β‐R was restored to high activities, whereas EO and 3α‐R showed only low to marginal activities. It is concluded that only the larval midgut has a role in the inactivation of ecdysteroids by 3‐epimerization. © 1993 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain

ISSN:0739-4462    

DOI:10.1002/arch.940230406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940230401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY