摘要:

AbstractThe distribution of digestive proteinases in either the anterior and posterior midgut or between the midgut epithelium and ectoperitrophic and endo‐peritrophic spaces in the midgut were examined in the European corn borer,Ostrinia nubilalis. Trypsin, chymotrypsin, elastase, and aminopeptidase activities were the same in the anterior and posterior halves of the midgut. Of the total aminopeptidase activity, 95% was located in the midgut epithelium, and 90% of the trypsin, 97% of chymotrypsin, and 93% of the elastase activity were found in the midgut lumen. Trypsin, measured by hydrolysis of benzoyl‐L‐arginine ethyl ester, and chymotrypsin levels were significantly higher in the ectoperitrophic space compared to the endoperitrophic space. Digestion in the midgut is proposed to be sequential with tryptic digestion occurring in the endoperitrophic space. Ingested protein is digested further in the ectoperitrophic space by the action of elastase, chymotrypsin, and a second trypsin. Final digestion occurs by an intracellular aminopeptidase. © 1995 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/arch.940280202

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

年代:1995

数据来源: WILEY

摘要:

AbstractYolk proteins (YP1, YP2, and YP3) of the fall webworm,Hyphantria cunea, are of relatively low molecular weight. Yolk protein‐2 (YP2) was purified from gel slices and by KBr density gradient ultracentrifugation followed by ion exchange chromatography. YP2 is composed of one subunit with a molecular weight of 35.5 kDa. YP2 contains neutral lipids (diacylglycerol and triacylglycerol) and phospholipids (phosphatidylcholine and phosphatidylethanolamine). The neutral lipids are largely composed of lauric acid and palmitoleic acid. YP2 contains relatively large amounts of glutamic acid and aspartic acid but small amounts of tyrosine, phenylalanine, and methionine. YP2 is a vitellin (Vn) synthesized by the fat body. Vitellogenin‐2 (Vg2), the precursor of YP2, is present in very small amounts in the hemolymph. Lipophorin and storage protein also are found in the ovary ofH. cunea, and these proteins do not immunologically cross‐react with YP2. YP2 is detected in first instar larvae but completely disappears during the second instar, indicating that YP2 is intensively utilized during postembryonic development. Anti‐YP2 antibodies cross‐react with ovarial extracts ofBombyx moribut not with those of insects from other orders such asCletus schmidti(Hemiptera),Lucilia illustris(Diptera),Anechura japonica(Dermaptera),Periplaneta americana(Dictyoptera), andDucetia japonica(Orthoptera). © 1995 Wiley

ISSN:0739-4462    

DOI:10.1002/arch.940280203

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

年代:1995

数据来源: WILEY

摘要:

AbstractA monoclonal antibody, directed against an H+translocating V‐ATPase of the midgut ofManduca sexta, has been used for immunolocalization studies in ovarian follicles and testes ofManduca sexta. In testes, no distinct staining above background levels was observed. In vitellogenic follicles, V‐ATPase immunoreactivity first appears in the cytoplasm of the trophocytes and then in the oocyte, but by far the strongest reaction is present in the region of the oolemma during endocytosis. All types of follicle cells surrounding both the oocyte and the trophocyte compartments show a distinct positive reaction. In the cylindrical follicle cells surrounding the oocyte, the immunoreactivity is clearly restricted to the basal part. Our results suggest an important role for V‐ATPase in vitellogenin uptake inManduca, similar to that suggested on electro‐physiological grounds inHyalophora cecropia. © 1995 Wiley

ISSN:0739-4462    

DOI:10.1002/arch.940280204

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn the mosquitoAedes albopictus, two potential RNA polymerase I promoters that map 531 and 143 nucleotides upstream of the 18S rRNA gene have been defined on the basis of sequence homology with rRNA promoters from other species. Using the polymerase chain reaction, we confirmed that a 717 nucleotide region spanning the upstream (‐531) and downstream (‐143) promoters is homogeneous in genomic DNA and in cloned DNA. DNA probes representing each of these promoters, as well as upstream “spacer” promoters, exhibited protein‐binding activity, and each unlabeled probe was an effective competitor of protein binding with the other probes, suggesting that these potential regulatory sequences interact with a common protein(s). Analysis of precursor ribosomal RNAs accumulated during temperature shock indicated that transcription is initiated primarily at the upstream (‐531) promoter. RNAse protection and primer extension analyses confirmed the predominant use of this promoter, both in cultured cells and in mosquito life stages. © 1995 Wil

ISSN:0739-4462    

DOI:10.1002/arch.940280205

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

年代:1995

数据来源: WILEY

摘要:

AbstractA five‐residue myotropic peptide,Manduca sextamidgut myotropin I (Mas‐MG‐MT I), was isolated from an extract of 800 midguts of fifth instar larvae of the tobacco hornworm,Manduca sexta. It was purified by reverse phase and normal phase HPLC. Myotropic activity was screened by a heterologousLocusta migratoriaoviduct bioassay. Sequence analysis, amino acid composition analysis, and comparison of candidate synthetic peptides in the amide and acid form revealed the following primary structure: Ala‐Glu‐Pro‐Tyr‐Thr‐NH2. This is the first fully identified peptide isolated directly from the midgut of an insect species. Few significant sequence homologies with known vertebrate and invertebrate peptides have been found. © 1995

ISSN:0739-4462    

DOI:10.1002/arch.940280206

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe determined the contribution of the peripodial membrane to chitin synthesis in cultured wing imaginal discs ofSpodoptera frugiperda. This was accomplished by examining chitin synthesis in vitro in intact imaginal discs, in the peripodial membrane, and in imaginal discs in which the peripodial membrane had been injured. Chitin synthesis in peripodial membrane‐deprived imaginal discs, peripodial membrane injured imaginal discs, and peripodial membrane fragments was assessed by measuring incorporation of [14C]GlcNAc after treatment with 20‐hydroxyecdysone in tissue culture. Removing or injuring the peripodial membrane resulted in a marked decrease in ecdysteroid‐dependent chitin synthesis in these wing discs compared with intact wing discs. In addition, a break in the ecdysteroid treatment of 4 h reduced chitin synthesis in the wing discs substantially. These biochemical experiments were supplemented with ultrastructural and immunocytochemical approaches. A wheat germ agglutinin colloidal gold complex was used to visualize the presence of chitin synthesized by wing discs including the peripodial membrane. These experiments confirmed the importance of an intact peripodial membrane for optimal production of cuticle by the wing pouch. Our results demonstrate that for opti‐ma1 production of chitin in tissue culture, wing discs must be treated with 20‐hydroxyecdysone for an uninterrupted period of 48 h, and the peripodial membrane of these imaginal discs must be present and uninjured. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United State

ISSN:0739-4462    

DOI:10.1002/arch.940280207

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

年代:1995

数据来源: WILEY

摘要:

AbstractTwo types of trypsin activity were detected inAnopheles albimanus, a constitutive and an inductive component, which have identical immunopatterns. The constitutive trypsin in synthesized shortly after eclosion and is retained in the midgut epithelial cells. The inductive trypsin is synthesized and released continuously after a blood meal has been ingested; maximal activities vary between 12 h and 18 h after a blood meal. Once digestion is completed, trypsin is excreted, but the constitutive trypsin level is restored within 24 h, before the next blood meal is taken. InA. gambiae, A. Stephensi, and A. quadrimaculatus, the constitutive trypsin component is also present, but at much lower levels. InA. albimanusfed multiple blood meals at 24 h intervals, trypsin oscillates at nearly maximal levels as long as blood is present in the midgut and depending on the ovarian status. Expression of the two trypsin components inA. albimanuswas found to be independent of the neurosecretory system, but synthesis of the constitutive trypsin appears to require the presence of the corpora allata. In all species tested, chymotrypsin is secreted after a blood meal in a similar temporal pattern as trypsin, but it is never present before the blood meal. Reinvestigating several aedine species for the presence of chymotrypsin by using different substrates revealed measurable quantities in blood‐fed females compared to earlier reports. Equally, aminopeptidase activity is present in all species tested and characterized by a constitutive component. Its activities follow different temporal patterns than the endopeptidases. © 1995 Wiley‐Liss,

ISSN:0739-4462    

DOI:10.1002/arch.940280208

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

年代:1995

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940280201

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

年代:1995

数据来源: WILEY