Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INSECTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed1994

Low-frequency echolocation enables the bat Tadarida teniotis to feed on tympanate insects.

The European free-tailed bat, Tadarida teniotis, forages in uncluttered airspace by using intense narrow-band echolocation calls with low frequency (11-12 kHz), and feeds on relatively large flying insects, mainly (90% by volume) of the tympanate orders Lepidoptera and Neuroptera. The use of low-frequency echolocation calls without strong harmonics appears to be a specialization for long-range detection of large, tympanate insects, which are less well represented in the diet of most other aerial-hawking bats. The results provide evidence in support of the allotonic frequency hypothesis, i.e. that use of echolocation calls with frequencies above or below the best hearing of tympanate insects is an adaptation to increase the availability of these insects.

Animals↗
PubMed2000

Wolbachia infection frequencies in insects: evidence of a global equilibrium?

Wolbachia are a group of cytoplasmically inherited bacteria that cause reproduction alterations in arthropods, including parthenogenesis, reproductive incompatibility, feminization of genetic males and male killing. Previous general surveys of insects in Panama and Britain found Wolbachia to be common, occurring in 16-22% of species. Here, using similar polymerase chain reaction methods, we report that 19.3% of a sample of temperate North American insects are infected with Wolbachia, a frequency strikingly similar to frequencies found in two other studies in widely separated locales. The results may indicate a widespread equilibrium of Wolbachia infection frequencies in insects whose maintenance remains to be explained. Alternatively, Wolbachia may be increasing in global insect communities. Within each of the three geographic regions surveyed, Hymenoptera are more frequently infected with A group Wolbachia and Lepidoptera more frequently infected with B group Wolbachia.

Animals↗
PubMed2001

Plant polyploidy and non-uniform effects on insect herbivores.

Genomic duplication through polyploidy has played a central role in generating the biodiversity of flowering plants. Nonetheless, how polyploidy shapes species interactions or the ecological dynamics of communities remains largely unknown. Here we provide evidence from a 4 year study demonstrating that the evolution of polyploidy has reshaped the interactions between a widespread plant and three species of phytophagous moths. Our results show that polyploidy has produced non-uniform effects, with polyploids less attacked by one insect species, but significantly more attacked by two other species. These results suggest that the evolution of plant polyploidy may not generally confer uniform resistance to multiple species of insect herbivores. In the absence of such a uniform release, the extreme evolutionary success of polyploid plants is probably due to factors other than escape from herbivory. Together, these results suggest that a primary consequence of plant polyploidy may be to shape the ecological structure of plant-insect interactions, thereby providing opportunities for diversification in both plant and insect taxa.

Animals↗
PubMed2006

Self-similar patterns of nature: insect diversity at local to global scales.

The insects are probably the most hyperdiverse and economically important metazoans on the planet, but there is no consensus on the best way to model the dimensions of their diversity at multiple spatial scales, and the huge amount of information involved hinders data synthesis and the revelation of 'patterns of nature'. Using a sample of more than 600k insect species in the size range 1-100mm, we analysed insect body sizes and revealed self-similar patterns persisting across spatial scales from several hectares to the World. The same patterns were found in both Northern and Southern Hemispheres. The patterns include: parallel rank-abundance distributions; flatter species-area curves in smaller insects-indicating their wider geographical distribution; the recurrence of the same species-rich family in the same body-size class at all spatial scales-which generates self-similar size-frequency distributions (SFDs)-and the discovery that with decreasing mean body size, local species richness represents an increasing fraction of global species richness. We describe how these 'rationalizing' patterns can be translated into methods for monitoring and predicting species diversity and community structure at all spatial scales.

Animals↗
PubMed1999

Studying insect diversity in the tropics.

Understanding the extent and causes of insect diversity in the humid tropics is one of the major challenges in modern ecology. We review some of the current approaches to this problem, and discuss how future progress may be made. Recent calculations that there may be more than 30 million species of insect on earth have focused attention on the magnitude of this problem and stimulated several new lines of research (although the true figure is now widely thought to be between five and ten million species). We discuss work based on insecticidal logging surveys; studies of herbivore and parasitoid specificity; macroecological approaches; and the construction of food webs. It is argued that progress in estimating insect diversity and in understanding insect community dynamics will be enhanced by building local inventories of species diversity, and in descriptive and experimental studies of the trophic structure of communities. As an illustration of work aimed at the last goal, we discuss the construction and analysis of quantitative host-parasitoid food webs, drawing on our work on leaf miner communities in Central America.

Animals↗
PubMed1990

Structural and immunological characterization of human cytomegalovirus gp55-116 (gB) expressed in insect cells.

The gene encoding the major envelope glycoprotein complex, gp55-116 (gB), of human cytomegalovirus (HCMV) was expressed at high levels in insect cells utilizing a recombinant baculovirus. The mature intracellular form of the insect-derived gp55-116 was a protein of Mr 150K which contained approximately 50K of N-linked oligosaccharides. The oligosaccharide linkages were almost exclusively endoglycosidase H-sensitive. The 150K protein was processed, presumably by proteolytic cleavage, to yield at least one of the previously defined cleavage products of the gp55-116. This processing step was significantly less efficient in insect cells than the analogous step in mammalian cells. Finally, the insect-derived gp55-116 was highly immunogenic in experimental animals and readily recognized by antibodies contained within HCMV-immune human serum, suggesting that this recombinant protein warrants further study as a potential HCMV subunit vaccine candidate.

Animals↗
PubMed1992

Expression in insect cells and immune reactivity of a 28K tegument protein of human cytomegalovirus.

The gene encoding the highly antigenic 28K (pp28) tegument phosphoprotein of human cytomegalovirus (HCMV) was expressed in insect cells utilizing a recombinant baculovirus. The mature intracellular form of the recombinant-derived pp28 had mobility on SDS-polyacrylamide gels similar to that of native pp28 from HCMV strain Towne-infected human foreskin fibroblasts (HFFs). In vitro labelling of recombinant Autographa california nuclear polyhedrosis virus-infected Spodoptera frugiperda cells or of HCMV-infected HFFs with [32P]orthophosphate followed by immunoprecipitation showed that both the insect cell-derived and HCMV strain Towne-infected fibroblast-derived pp28 were phosphorylated. The mobility of pp28 derived from these two sources as well as from extracellular HCMV virions indicated the existence of multiple charged forms of the protein, and a difference in the relative amounts of these forms expressed in HCMV-infected HFFs and recombinant baculovirus-infected insect cells. The recombinant pp28 expressed in insect cells was readily and specifically recognized by antibodies to native pp28, including HCMV-seropositive human serum, and was used in an ELISA to screen human sera for seropositivity.

Animals↗
PubMed1994

Expression of equine herpesvirus type 1 glycoprotein gp14 in Escherichia coli and in insect cells: a comparative study on protein processing and humoral immune responses.

The extracellular portion (amino acids 1 to 844) of the equine herpesvirus type 1 (EHV-1) glycoprotein gp14, the homologue of gB of herpes simplex virus, was expressed in Escherichia coli and in insect cells using a recombinant baculovirus. Immunoblot analysis revealed that the recombinant E. coli expressed a fusion protein of M(r) 135K which was composed of the truncated gp14 and the maltose-binding protein (MBP) provided by the vector and a 90K protein lacking the MBP moiety. Both proteins were sequestered within the cells in form of inclusion bodies. Infection of insect cells with the recombinant baculovirus resulted in the production of a 115K to 118K glycoprotein which was cleaved intracellularly into two subunits of M(r) 55K and 63K to 65K. The cleaved subunits were secreted into the cell culture supernatant and formed disulphide-linked dimers of M(r) 120K to 122K. The recombinant proteins produced in E. coli and in insect cells elicited EHV-1-specific antibodies in goats as demonstrated by Western blot analysis. The gp14 expressed in insect cells induced antibodies with virus-neutralizing activity. In contrast, the truncated gp14 expressed by E. coli failed to elicit neutralizing antibodies. The results suggest that post-translational modification of the EHV-1 gp14 may be important for the expression of epitopes necessary for the induction of neutralizing antibodies.

Animals↗
PubMed2004

Sequence analysis and genomic organization of a new insect picorna-like virus, Ectropis obliqua picorna-like virus, isolated from Ectropis obliqua.

The complete nucleotide sequence of a new insect picorna-like virus, Ectropis obliqua picorna-like virus (EoPV), which causes a fatal infection of Ectropis obliqua larvae, has been determined. The genomic RNA of EoPV is 9394 nt in length and contains a single, large open reading frame (nt 391-9351) encoding a polyprotein of 2987 aa. Sequence comparisons with other viral polyproteins revealed that the consensus sequences for picornavirus RNA helicase, protease and RNA-dependent RNA polymerase proteins are found on the genome in order in the 5'-->3' direction. All structural genes were located at the 5' terminus. In terms of sequence similarity, identity and genome organization, EoPV resembles mammalian picornaviruses and three other insect picorna-like viruses: Infectious flacherie virus of silkworm, Sacbrood virus of honeybee and Perina nuda picorna-like virus (PnPV). Phylogenetic analysis showed that EoPV is most closely related to PnPV and suggests that these four insect picorna-like viruses might constitute a new group of insect-infectious RNA viruses.

Amino Acid Sequence↗
PubMed1998

Characterization of SKT1, an inwardly rectifying potassium channel from potato, by heterologous expression in insect cells.

A cDNA encoding a novel, inwardly rectifying K+ (K+in) channel protein, SKT1, was cloned from potato (Solanum tuberosum L.). SKT1 is related to members of the AKT family of K+in channels previously identified in Arabidopsis thaliana and potato. Skt1 mRNA is most strongly expressed in leaf epidermal fragments and in roots. In electrophysiological, whole-cell, patch-clamp measurements performed on baculovirus-infected insect (Spodoptera frugiperda) cells, SKT1 was identified as a K+in channel that activates with slow kinetics by hyperpolarizing voltage pulses to more negative potentials than -60 mV. The pharmacological inhibitor Cs+, when applied externally, inhibited SKT1-mediated K+in currents half-maximally with an inhibitor concentration (IC50) of 105 microM. An almost identical high Cs+ sensitivity (IC50 = 90 microM) was found for the potato guard-cell K+in channel KST1 after expression in insect cells. SKT1 currents were reversibly activated by a shift in external pH from 6.6 to 5.5, which indicates a physiological role for pH-dependent regulation of AKT-type K+in channels. Comparative studies revealed generally higher current amplitudes for KST1-expressing cells than for SKT1-expressing insect cells, which correlated with a higher targeting efficiency of the KST1 protein to the insect cell's plasma membrane, as demonstrated by fusions to green fluorescence protein.

Amino Acid Sequence↗
PubMed1987

Bacillus thuringiensis section sign-Endotoxin Expressed in Transgenic Nicotiana tabacum Provides Resistance to Lepidopteran Insects.

The crystal proteins, or section sign-endotoxins, of Bacillus thuringiensis are specifically lethal to Lepidopteran insects. We utilized a truncated and modified portion of a cloned crystal protein gene to construct a chimeric gene capable of expression in plant cells. Using an Agrobacterium tumefaciens binary vector system, we then transferred the chimeric toxin gene into tobacco (Nicotiana tabacum cv Havana 425) cells and regenerated recombinant plants. One to several copies per cell of the toxin gene are routinely present in the recombinant plants. Hybridization experiments demonstrated that these plants had a new RNA species of the size expected for the truncated toxin mRNA, and a polypeptide having the mobility expected for the truncated toxin was detected by immunoblotting. Significant variation was found in the levels of toxin-specific RNA expression between different recombinants, but the levels of hybridizing RNA in transformants correlated with the level of toxicity demonstrated against Manduca sexta (tobacco hornworm), and other Lepidopteran insects. The recombinant genes were transmitted to progeny and resistance to insects was maintained, thus demonstrating that the introduction of toxin genes into plants may be a practical method of providing protection against certain insect pests.

Journal Article↗
PubMed2004

Molecular phylogenetic evidence for an extracellular Cu Zn superoxide dismutase gene in insects.

Representatives of three ancient gene families of the antioxidant enzyme superoxide dismutase (SOD) can be found in most metazoans. In mammals and Caenorhabditis elegans, there is at least one gene each of the cytoplasmic, mitochondrial and extracellular lineages of SOD genes. The cytoplasmic SOD was one of the first enzymes to be implicated in ageing due to its protection against damaging oxygen free radicals. In contrast to other metazoans, insects were thought to lack a gene for the extracellular SOD. We have cloned and sequenced an SOD mRNA in the ant Lasius niger that appears to belong to this extracellular family. Subsequent searches and analyses of SOD gene sequences in insect databases revealed that insects do indeed express all three SOD genes including the extracellular form. We conclude that insects as well as other metazoans appear to have the full repertoire of the three families of SOD.

Amino Acid Sequence↗
PubMed1998

Pantropic retroviral vectors mediate somatic cell transformation and expression of foreign genes in dipteran insects.

The control of insects that transmit disease and damage crops has become increasingly difficult. The ability to genetically engineer insects would facilitate strategies to protect crops and block arthropod vector-borne disease transmission. Transformation vectors based on insect transposable elements have been developed, but most have limited host ranges. A promising alternative is the pantropic retroviral vector, which is packaged with the envelope glycoprotein from vesicular stomatitis virus and is replication-defective. We show here that pantropic murine retroviral vectors can mediate high-level expression of foreign genes in somatically transformed insect larvae and adults of three dipteran genera. This success demonstrates the potential for germline transformation mediated by pantropic retroviral vectors.

Aedes↗
PubMed1977

Lysozyme from the insect Ceratitis capitata eggs.

1. Lysozyme from eggs of the Dipterous Ceratitis capitata (Wiedeman) has been purified by ion-exchange chromatography and gel filtration and its physicochemical properties have been investigated. This is the first insect lysozyme characterized so far and it exhibits some properties different to those described for other animal lysozymes. 2. Lysozyme from the insect eggs has a molecular weight of about 23200 and a sedimentation coefficient of 2.4 S. Molecular weight determination by sodium dedecylsulphate gel electrophoresis indicates that the molecule consists of a single polypeptide chain. 3. This lysozyme preparation shows notable stability at acidic pH values and lability at alkline pH values. It shows a single optimum pH at about 6.5.4. Chitinase/muramidase specific activity ratio is around 350 times higher for the insect lysozyme than for the hen egg-white enzyme. 5. The amino-acid composition shows the presence of one tryptophan residue per molecule of enzyme. This fact differentiates the lysozyme from insect eggs from other animal and plant lysozymes. From the amino acid composition, the absorption coefficient and the partial specific volume are calculated. 6. Glycine is the N-terminal residue.

Amino Acids↗
PubMed1978

Lipid-bound oligosaccharides in insects.

Membrane preparations from immature stages of the fruit fly Ceratitis capitata catalyze the transfer of mannose from GDP-[14C]mannose into lipid-linked oligosaccharides. These compounds behave as polyprenyl derivatives and their formation is stimulated by the addition of an acidic glycolipid fraction isolated from insects. The mannose-labeled oligosaccharides are attached to the poly-isoprenol by a pyrophosphoryl linkage and can be released by mild acid hydrolysis. The trisaccharide lipid has been partially characterized. The results indicate that the compound is polyprenyl-pyrophosphate-N,N'-diacetylchitobiose-mannose. Incubation of dolichyl phosphate [14C]mannose or lower 14C-labeled oligosaccharide lipids with unlabeled GDP-mannose and the insect enzyme leads to the labeling of a higher lipid-bound oligosaccharide. When UDP-N-acetyl[14C]glucosamine was incubated with insect membranes a 14C-labeled chitobiosyl lipid was synthesized. If unlabeled GDP-mannose was also present, the 14C label appeared in the trisaccharide and higher oligosaccharide lipids. Preliminary evidence indicates that the insect polyprenyl oligosaccharides described here might participate in glycoprotein biosynthesis.

Animals↗
PubMed1990

Binding of ADP and adenosine 5'-[beta, gamma-imido]triphosphate to insect flight muscle fibrils.

We have studied the binding of ADP and adenosine 5'-[beta, gamma-imido]triphosphate (AdoPP[NH]P) to insect flight muscle fibrils. We find that 25% of the myosin heads, presumably those which do not interact with actin, bind AdoPP[NH]P with a binding constant greater than 3 X 10(6) M-1, similar to the binding constant of the same compound to the rabbit myosin heads which do not overlap with actin. The remaining heads in insect myofibrils bind AdoPP[NH]P with an association constant of 8 X 10(3) M-1, which is eight times stronger than the affinity of this compound for rabbit myosin heads in overlap with actin. Therefore, in contrast to the situation with rabbit myofibrils where AdoPP[NH]P binds much more weakly than ADP, with insect myofibrils these two adenosine phosphates bind with almost equal affinity. This is consistent with the numerous structural studies on insect flight muscle which were interpreted on the basis that most of the actomyosin sites were saturated with nucleotide at an AdoPP[NH]P concentration of 1 mM.

Adenosine Diphosphate↗
PubMed1996

A new scorpion venom toxin paralytic to insects that affects Na+ channel activation. Purification, structure, antigenicity and mode of action.

A new toxin, BotIT2, with a unique mode of action on the isolated giant axon of the cockroach Periplaneta americana and DUM (dorsal unpaired median) neurons, has been purified from the venom of the scorpion Buthus occitanus tunetanus. Its structural, antigenic and pharmacological properties are compared to those of three other groups of neurotoxins found in Buthidae scorpion venoms. Like excitatory, depressant and alpha-type insect-selective neurotoxins, BotIT2 is toxic to insects, but shows the following common and distinctive characteristics. (a) As alpha-type toxins, BotIT2 lack strict selectivity to insects; they have measurable but low toxicity to mice. (b) As depressant toxins and unlike alpha-type toxins, BotIT2 is able to displace iodinated AaHIT from its binding sites in insect neuronal membranes. This indicates that the binding site for BotIT2 is identical, contiguous or in allosteric interaction with that of AaHIT and depressant toxins. (c) The BotIT2 amino acid sequence shows strong similarity to depressant toxins. However, unexpectedly, despite this high sequence similarity, BotIT2 shares moderate cross-antigenic reactivity with depressant toxins. (d) Voltage and current-clamp studies show that BotIT2 induces limited depolarization concomitantly with the development of depolarizing after potential, repetitive activity and later plateau potentials terminated by bursts. Under voltage-clamp conditions, BotIT2 specifically acts on Na+ channels by decreasing the peak Na+ current and by simultaneously inducing a new current with very slow activation/deactivation kinetics. The voltage dependence of this slow current is not significantly different from that of the control current. These observations indicate that BotIT2 chiefly modifies the kinetics of axonal and DUM neuronal membrane Na(+)-channel activation.

Amino Acid Sequence↗
PubMed1997

Human endothelin receptors ET(A) and ET(B) expressed in baculovirus-infected insect cells--direct application for signal transduction analysis.

We expressed human endothelin receptors, ET(A) and ET(B), in insect Sf9 cells infected by recombinant baculoviruses that contained the respective cDNAs. Ligand-binding experiments showed that the two expressed receptors have the same affinities as observed for the receptors in mammalian cells, i.e. the ET(A) receptor showed an affinity order of ET-1 > or = ET-2 >> ET-3, and the ET(B) receptor remained nonselective for three isopeptide ligands. The ET(B) receptor was purified by affinity chromatography with K9-biotinyl-ET-1 without losing the ligand-binding activity from the membrane of infected Sf9 cells. Protein chemical analysis of the purified ET(B) receptor showed that it is glycosylated, and that the N-terminal 38-amino-acid peptide is susceptible to proteolytic digestion, resulting in a small 35-kDa receptor like that found in the human placenta. Surprisingly, the infected and unlysed cells showed a strong intracellular Ca2+ concentration increase ([Ca2+]i), which was generated by a unique signal-transduction pathway consisting of the insect GTP-binding protein and human endothelin receptors expressed in the late phase of virus infection. Due mainly to an efficient expression (over 200,000 receptors/cell), to a low background owing to no endogenous homolog receptor in insect Sf9 cells, and to a sensitive fluorescent reagent Fura-2, this insect Sf9 cell system can detect the [Ca2+]i induced by picomolar levels of endothelin-receptor. We propose that this highly sensitive system be used to screen for potential antagonists/agonists of endothelin receptors.

Amino Acid Sequence↗