摘要:

AbstractA new approach to insect control—using sodium trichloroacetate (NaTCA) to inhibit synthesis of the hydrophobic cuticular lipids that protect insects from dehydration—was tested onTriatoma infestans. In vivo and in vitro studies of incorporation of radioactive precursors showed diminished cuticular hydrocarbon synthesis after NaTCA treatment. Thin layer chromatography and scanning electron microscopy showed disruption of the cuticular lipid layer of NaTCA‐treated insects, which also have increased mortality and altered molting cycles. NaTCA treatment enhanced the penetration and increased the lethality of a contact insecticide. © 1994 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/arch.940250302

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

年代:1994

数据来源: WILEY

摘要:

AbstractTriatoma infestanseggs are shown to synthesize hydrocarbons. Radio‐gas chromatography was used to demonstrate metabolism of [1‐14C]propionate into precursor methyl‐branched fatty acids and into methyl‐branched hydrocarbons inT. infestanseggs. These reactions have not been demonstrated previously in insect eggs. An in vivo study showed that hydrocarbons are also transported to eggs by the hemolymph. Inhibition of hydrocarbon synthesis by sodium trichloroacetate (NaTCA) was correlated with reduced oviposition, reduced hatchability, and reduced insect survival. Scanning electron microscopy showed impoverishment of the eggs' epicuticular waxes following NaTCA treatment. © 1994 Wiley

ISSN:0739-4462    

DOI:10.1002/arch.940250303

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe brain ofTenebrio molitorexhibited marked fluctuations in acetylcholinesterase (AChE) activity throughout metamorphosis. This was true AChE activity, since it was inhibited by high substrate concentrations and by 10 μM of the specific AChE inhibitor BW284C51 [(1,5‐bis'4‐allyldimethylammoniumphenyl)‐pentan‐3‐one dibromide] but not by iso‐OMPA (tetraisopropylpyrophosphoramide), a cholinesterase (but not AChE) inhibitor. The histochemical AChE activity was localized in the neuropile and the nuclear envelope of neurons and glial cells. The enzyme extracted from brains with 1% Triton X‐100 and 1 M NaCl sedimented as a single peak in a sucrose density gradient, with a sedimentation coefficient of 5.4S. This single AChE sedimentation peak was mainly due to an amphiphilic dimeric form. AChE activity per brain increased in newly ecdysed pupa. AChE activity per milligram of protein exhibited a peak in the mid‐pupa which could be correlated to the increase in ecdysteroid titers. © 199

ISSN:0739-4462    

DOI:10.1002/arch.940250304

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

年代:1994

数据来源: WILEY

摘要:

AbstractA parasitism‐specific protein was originally identified in the hemolymph of the Caribbean fruit flyAnastrepha suspensaparasitized by the braconid waspDiachasmimorpha (Biosteres) longicaudatausing single‐dimensional (1‐D) sodium dodecyl sulfate (SDS) PAGE. We now show that the protein is comprised of two closely migrating species both of which are glycoproteins of ≈︁ 24,000 Daltons (24 kD). The proteins were poorly resolved from whole hemolymph by 1‐D SDS PAGE, but were well resolved by two‐dimensional (2‐D) PAGE and isoelectric focusing. They have pl's of ≈︁ 6.3 and 6.7 and contain Man residues, based on their affinity for concanavalin A (Con A). The presence of GlcNAc, NeuAc, and GalNAc residues in both proteins was implicated by their binding to wheat germ agglutinin (WGA). The proteins bound WGA more intensely following mannosidase treatment which eliminated their affinity to Con A and further implicated the presence of internal GlcNAc residues. However, binding of the proteins to WGA in the presence of competing GlcNAc (1 M) was reduced but not eliminated and suggested that in addition to GlcNAc, other WGA‐binding sugar moieties, possibly NeuAc, a Sia, were present. To evaluate the presence of NeuAc, we treated the hemolymph withVibrio choleraeneuraminidase which specifically cleaves terminal Sia. Samples of the neuraminidase‐digested proteins were evaluated by WGA binding and Western blotting with the use of an anti‐24 kD rabbit polyclonal serum to determine whether desialation eliminated the proteins' affinity to WGA or their immunoreactivity. Our results show that partial digestion of the 24 kD proteins withVibrio choleraeneuraminidase resulted in two immunoreactive bands in Western blots of 1‐D gels but only one of these, the upper undigested 24 kD band, bound WGA. This confirmed the presence of Sia residues in the proteins and demonstrated that desialation increased their relative electrophoretic mobilit

ISSN:0739-4462    

DOI:10.1002/arch.940250305

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine the effects of potent inhibitors of chitin synthesis on an organ culture test system as a basis for determining the mode of action of such compounds. Consequently, we investigated the action of chlorfluazuron (CFA), diflubenzuron (DFB), and teflubenzuron (TFB) on uptake and incorporation into chitin of [14C]N‐acetyl‐D‐glucosamine ([14C]GlcNAc) in wing imaginal discs cultured in vitro.Spodoptera frugiperdawing imaginal discs provided a highly responsive test system for studying the inhibition of ecdysteroid‐dependent chitin synthesis in a target tissue in vitro.All three inhibitors blocked ecdysteroid‐dependent [14C]GlcNAc incorporation into chitin by the wing imaginal discs. The effectiveness of the inhibitors was not affected by the time of their application, i.e., exposures before, during, or after 20‐hydroxyecdysone treatment were equally effective in inhibiting chitin synthesis. Thus, exposure of freshly dissected discs to CFA for periods as short as 15 min inhibited approximately 90% of the chitin synthesis measured 72 h later. In contrast to previous in vivo studies all three inhibitors were similar in their effectiveness in vitro. However, while all three compounds inhibited [14C]GlcNAc incorporation in a similar dose‐dependent manner, only DFB and TFB reduced but did not block uptake of GlcNAc. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United S

ISSN:0739-4462    

DOI:10.1002/arch.940250306

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

年代:1994

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940250301

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

年代:1994

数据来源: WILEY