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At least 1,513 records · Page 84Linked to original sources
PubMed2005

Intraspecific variability in Triatoma dimidiata (Hemiptera: Reduviidae) populations from Guatemala based on chemical and morphometric analyses.

The intraspecific variability of Triatoma dimidiata Latreille, a major vector of Chagas disease, was studied in four departments of Guatemala. Insects were collected from either domestic and sylvatic habitats, and their cuticular hydrocarbon pattern and head morphology were analyzed using ordination and classification techniques. A significant discrimination was obtained both with morphometric and hydrocarbon analyses. Insects from northern departments were easily differentiated from southern conspecifics. Distinctive hydrocarbon pattern and head shape were detected for insects collected from caves in the north central region of the country, posing concern about their taxonomic status.

Animals↗
PubMed1990

Studies on prophenoloxidase activation in the mosquito Aedes aegypti L.

This study, the first of its kind in a mosquito vector species, demonstrates the feasibility of studying prophenoloxidase activation in an insect containing not more than a few microliters of hemolymph. Mosquito phenoloxidase was found to be in an inactive proenzyme form, prophenoloxidase. Mosquito prophenoloxidase required bivalent cation for its activation; Ca2+ was found to be the most efficient for activation. Concomitant amidase activity was also observed prior to phenoloxidase activity. Through Western blotting, using a cross-reactive silkworm antiprophenoloxidase antibody, our results strongly suggest that mosquito prophenoloxidase activation resulted from limited proteolysis. Protease inhibitor studies reinforced this contention showing the involvement of (a) serine protease(s) with trypsin-like activity in the activation of mosquito prophenoloxidase.

Aedes↗
PubMed1997

Folding-dependent binding of thyrotropin (TSH) and TSH receptor autoantibodies to the murine TSH receptor ectodomain.

The mouse TSH receptor ectodomain (mTSHR-ecd) was amplified from murine thyroid complementary DNA and ligated into the pAcGP67B insect cell vector, and the nucleotide sequence was confirmed. Employing a baculovirus-insect cell system, the mTSHR-ecd (amino acids 22-415) was expressed as a fusion protein with the gp67 insect cell signal sequence at the NH2-terminus and a C-terminal six-histidine tag. Protein expression was assessed by Western blot using a murine monoclonal antibody (recognizing amino acids 22-35) and a rabbit antipeptide antibody (recognizing amino acids 397-415). These antibodies detected two principal species of mTSHR-ecd, one glycosylated (66 kDa) and one nonglycosylated (52 kDa), in cell lysates of infected insect cells. More than 10% of these species were present in a water-soluble (cytosolic) fraction. This fraction was then used to purify, under native conditions, 100-microg amounts of mTSHR-ecd using nickel-nitrilo-triacetic (Ni-NTA) resin chromatography. The purified cytosolic mTSHR-ecd migrated as a homogeneous 66-kDa band visible on Coomassie blue-stained gels and was confirmed by Western blotting. We also purified the mTSHR-ecd from total cell lysates under denaturing conditions, followed by "in vitro" refolding on the Ni-NTA column. Under these conditions, milligram amounts of soluble mTSHR-ecd were obtained. This material consisted primarily of the 66-kDa glycosylated form, but in addition contained four or five lower molecular mass, partially glycosylated intermediates and the 52-kDa nonglycosylated form. Deglycosylation with either endoglycosidase F or H, reduced all mTSHR-ecd glycosylated species to a 52-kDa nonglycosylated form. Both the cytosolic and refolded mTSHR-ecd preparations inhibited the binding of [125I]TSH to the full-length human TSHR expressed in Chinese hamster ovary cells in a dose-dependent manner, with similar affinities. The affinity of such interactions was 3 orders of magnitude less than observed with native porcine TSHR and was further reduced by unfolding the mTSHR-ecd preparations. The cytosolic and refolded mTSHR-ecd were also recognized by hTSHR autoantibodies in the serum of patients with hyperthyroid Graves' disease. Such autoantibody binding to mTSHR-ecd was also markedly reduced by unfolding the antigen. These results demonstrated the successful production of large quantities of well characterized, biologically active, mTSHR-ecd antigen. In addition, the data showed that although the ectodomain of the mTSHR bound TSH, intact holoreceptor may be required for high affinity ligand binding. Whether the transmembrane region is required for direct ligand binding, as seen for other G protein-linked receptors, or whether it is needed to stabilize the ligand binding to the ectodomain and maintain a correctly folded state, remains unclear.

Amino Acid Sequence↗
PubMed1999

Evidence for an inactive transposable mariner-like element in Anopheles albimanus.

Transposable elements may eventually be used as transformation vectors of anti-Plasmodium genes in natural populations of Anopheles mosquitoes. The mariner transposable element is widespread in most animal phyla and we wished to test for its presence in the important Latin American malaria vector, Anopheles albimanus. Degenerate primers were designed from the consensus of insect mariner elements and used in a polymerase chain reaction to amplify a fragment of the predicted size from An. albimanus. The fragment was cloned, sequenced, and determined to be a mariner-like element through multiple alignment with known insect mariner elements. Dot blot and Southern blot analyses showed only one or a few elements per haploid genome. The cloned fragment was used as a probe to isolate similar sequences from an An. albimanus genomic DNA library. A 659-base-pair clone was 57% similar at the DNA level with mariner elements from Anopheles gambiae, Chrysoperla ptorapunda, and Haematobia irritans. This low sequence similarity is comparable to that found among mariner-like elements in all insects. However, conserved amino acid motifs were not discovered nor was a single open reading frame found. These aspects suggest that the An. albimanus mariner-like element may represent an ancient transposition event but that the element is no longer active, the typical open reading frame having been disrupted through nucleotide insertions and deletions.

Animals↗
PubMed1989

High-efficiency expression of mammalian beta-adrenergic receptors in baculovirus-infected insect cells.

Infection of a clonal isolate of Spodoptera frugiperda cells (Sf9) with a baculovirus expression vector harboring the cDNA encoding the beta-adrenergic receptor resulted in a high efficiency expression. At 48 hr post-infection, the level of expression of beta-adrenergic receptors was approximately 12 million/cell. Specific activities of crude lysates of infected Sf9 cells were approximately 30 pmol/mg of protein, 5-fold greater than those of membranes of high-expressor Chinese hamster ovary cells stably transfected with an SV-40 expression vector. One liter of infected Sf9 cells expresses 20-40 nmol of receptor. Autoradiography of membranes incubated with the beta-adrenergic antagonist [125I]iodoazidobenzylpindolol, photolyzed, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed 46,000- (presumably unglycosylated) and 48,000-Mr peptides for Sf9 cells as compared to approximately 65,000-Mr for Chinese hamster ovary cells. The baculovirus Sf9 system provides high-efficiency expression of receptor sufficient to permit physicochemical analyses.

Animals↗
PubMed2005

DNA evidence of Trypanosoma cruzi in the Chilean wild vector Mepraia spinolai (Hemiptera: Reduviidae).

Molecular evidence showed 46.2% of Trypanosoma cruzi infection in Mepraia spinolai insects from North-Central Chile, which is significantly higher than previous reports of up to 26% by microscopic observation. Our results show similar infection levels among nymphal stages, ranging from 38.3 to 54.1%, indicating that younger nymphs could be as important as older ones in parasite transmission. A cautionary note must be stressed to indicate the potential role of M. spinolai in transmitting T. cruzi in country areas due to the high infection level detected by molecular analysis.

Animals↗