摘要:

AbstractThe mechanism of recognition of foreignness and entrapment of invaders by the immune system of insects is unknown. In this report using hemocyte monolayer preparations and biochemical analysis we demonstrate the requirements for recognition ofE. coliin vitro, their entrapment by hemocytes, and nodule formation. A model system consisting of an isolated hemocyte protein (47 KDa), isolated hemocyte tyrosinase, isolated hemocytes, tyrosine, andE. coliwas used to obtain these results. The 47 kDa polypeptide has the ability to form adducts with tyrosine derivatives generated by the action of tyrosinase and to attach to theE. colisurface. The latter process takes place independently of tyrosinase activity. When theE. coli‐47KDa protein complex was overlaid on hemocyte monolayers followed by tyrosine and tyrosinase or vice versa, the bacteria were entrapped by hemocytes. The same results were obtained when the monolayers were overlaid with 47 KDa protein, followed byE. coli‐47 KDa protein complex and then tyrosine and tyrosinase. The same experimental procedure in test tubes resulted in nodule formation. These results permit us to propose that the most likely explanation for the entrapment ofE. colito hemocytes and the formation of nodules is the production ofE. coli‐47 KDa complexes, and their crosslinking through a quinone intermediate generated by the action of tyrosinase on hemocytes. © 1994 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/arch.940260102

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

年代:1994

数据来源: WILEY

摘要:

AbstractThe major lepidopteran storage protein arylphorin is selectively taken up into perivisceral fat body of prepupae by receptor mediated endocytosis. The arylphorin receptor was identified by ligand blotting and in vitro binding studies. Fat body membranes contain a glycosylated receptor protein with an apparent molecular weight of 80,000 that binds arylphorin with a KDof 9.02 × 10−8M. Competitive binding experiments revealed that the arylphorin receptor is identical with the previously identified VHDL receptor. Apparently a single receptor mediates the uptake of structurally distinct storage proteins. This storage protein receptor is present only in perivisceral fat body and only during the period around pupation when both storage proteins are sequestered. © 1994 Wiley‐Liss

ISSN:0739-4462    

DOI:10.1002/arch.940260103

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

年代:1994

数据来源: WILEY

摘要:

AbstractPeptidylglycine α‐hydroxylating monooxygenase (PHM), an enzyme involved in formation of neuropeptides with a C‐terminal amide functionality in mammals and amphibians, was isolated from the head of an invertebrate, the honeybee,Apis mellifera, and purified 220‐fold in 1% overall yield. The bee PHM has a molecular weight of 71,000, is membrane associated but can be solubilized with a detergent (n‐octyl‐β‐D‐glucopyranoside), and cross‐reacts with rabbit antibodies generated toward bacterially expressed rat PHM. In the presence of copper, oxygen, and ascorbic acid, the enzyme hydroxylates model tripeptides such as dansyl‐L‐Phe‐L‐Phe‐Gly on the methylene carbon of the glycine residue with retention of configuration. Using this tripeptide as substrate, theKmis 1.7 μM and the Vmaxis 2.3 nmol • μg−1• h−1. Treatment of the insect PHM with D‐Phe‐L‐Phe‐D‐vinylglycine, a substrate analogue and mechanism‐based inactivator of PHM from pig pituitary, results in irreversible loss of activity. The diastereomeric analogue, D‐Phe‐L‐Phe‐L‐vinylglycine, is only a c

ISSN:0739-4462    

DOI:10.1002/arch.940260104

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

年代:1994

数据来源: WILEY

摘要:

AbstractStudies were undertaken to determine the role of symbionts and UV exposure in biosynthesis of the aphid‐specific polyketides, sorbic acid and quinone pigments. Injection of adult potato aphids,Macrosiphum euphorbiae(Thomas), with the antibiotic rifampicin did not alter the level of sorbic or myristic acid in triglycerides of resultant progeny; pigmentation was also unaffected. However, antibiotic injection did produce marked physiological effects; progeny from injected aphids were smaller, slower to mature, and not fecund. Light microscopy confirmed that only 8% of rifampicin‐treated aphids contained mycetocytes; thus, symbiont involvement in the production of this unusual UV‐quenching short chain fatty acid is not supported. Following multigenerational exposure to long wavelength UV light, no substantial changes in sorbic acid content were detected in the potato aphid or the oleander aphid,Aphis neriiFonscolombe. Pigments from UV‐exposed oleander aphids had a peak absorbance at 390 nm, 70 nm lower than unexposed aphids. This suggests a photo‐protective role for the pigments of the sunlight‐inhabitingA. nerii; by contrast, no changes were observed in pigments ofM. euphorbiaewhich usually feeds in the shade. Injection of adult potato aphids with sodium [1‐14C]‐acetate rapidly labeled both sorbic acid and pigments, particularly among the latter a yellow pigment which co‐chromatographed with the dominant C15 yellow pigment of the oleander aphid. These data support the hypothesis that aphid C30 pigments are built up by coupling of “monomeric type” C15 pigments. Although aphid and not symbiont enzymes appear to synthesize these acetogenins, a possible biosynthetic link between sorbic acid and aphid pigments requires further clarification.

ISSN:0739-4462    

DOI:10.1002/arch.940260105

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

年代:1994

数据来源: WILEY

摘要:

AbstractThis study investigated the pharmacological profile of cyclodiene resistance inDrosophila melanogasterand the mode of action of a phenylpyrazole insecticide, JKU 0422. Toxicological studies were performed with a sucrose bait assay containing the synergist piperonyl butoxide. The Maryland strain ofD. melanogasterwas resistant to dieldrin, lindane, picrotoxinin, TBPS,p‐CN‐TBOB, and JKU 0422. In contrast, this strain was susceptible to cypermethrin and the avermectins MK‐243, abamectin, and abamectin 8,9‐oxide. Neurophysiological studies showed that both TBPS and JKU 0422 reversed the inhibitory action of GABA in central nerve preparations from susceptibleD. melanogaster. However, the response to these compounds was attenuated in nerve preparations from the resistant Maryland strain, which indicated that the resistance was expressed at the level of the nerve. Topical toxicity bioassays with JKU 0422 on susceptible (CSMA) and cyclodiene‐resistant (LPP) strains of German cockroach revealed a resistance ratio of 553‐fold for this compound. These studies demonstrate that cyclodiene resistance inD. melanogasterconfers broad cross resistance toward compounds thought to block the GABA‐gated chloride channel in a manner similar to the cyclodienes. Moreover, the cross resistance extends to JKU 0422, and resistance to this compound is also present in a strain of cyclodiene‐resistant German cockroach. These toxicological results, along with the neurophysiological studies, confirm that JKU 0422 has a mode of action that is similar to the cyclodienes and TBPS. These findings suggest that the introduction and use of new chloride channel antagonists as insecticides should be managed carefully in order to prevent the rapid development of resistance in the field. © 1994

ISSN:0739-4462    

DOI:10.1002/arch.940260106

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.940260101

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

年代:1994

数据来源: WILEY