The digestive system in Zygentoma as an insect model for high cellulase activity.

The digestive system of selected phytophagous insects has been examined as a potential prospecting resource for identification of novel cellulolytic enzymes with potential industrial applications. In contrast to other model species, however, limited detailed information is available that characterizes cellulolytic activity and systems in basal hexapod groups. As part of a screening effort to identify insects with highly active cellulolytic systems, we have for the first time, identified species of Zygentoma that displayed the highest relative cellulase activity levels when compared to all other tested insect groups under the experimental conditions, including model species for cellulolytic systems such as termite and cockroach species in Rhinotermitidae (formerly Isoptera) and Cryptocercidae (formerly Blattodea).

Differential heliothine susceptibility to Cry1Ac associated with gut proteolytic activity.

The Cry1Ac protein is the most active insecticidal toxin from the bacterium Bacillus thuringiensis (Bt) to members of the heliothinae subfamily in Lepidoptera, which includes some of the most devastating pests of corn and cotton worldwide. However, there are wide discrepancies in susceptibility among members of this subfamily in the US. Specifically, susceptibility to Cry1Ac in Helicoverpa zea (Hz) is >100-fold lower when compared to Heliothis virescens (Hv) larvae.

Alpha-arylphorin is a mitogen in the midgut cell secretome upon Cry1Ac intoxication.

Insecticidal crystal (Cry) proteins produced by the bacterium (Bt) target cells in the midgut epithelium of susceptible larvae. While the mode of action of Cry toxins has been extensively investigated, the midgut response to Cry intoxication and its regulation are not well characterized. In this work, we describe the secreted proteome (secretome) of primary mature midgut cell cultures from larvae after exposure to Cry1Ac toxin compared to control buffer treatment.

Expression of an endoglucanase from Tribolium castaneum (TcEG1) in Saccharomyces cerevisiae.

Insects are a largely unexploited resource in prospecting for novel cellulolytic enzymes to improve the production of ethanol fuel from lignocellulosic biomass. The cost of lignocellulosic ethanol production is expected to decrease by the combination of cellulose degradation (saccharification) and fermentation of the resulting glucose to ethanol in a single process, catalyzed by the yeast Saccharomyces cerevisiae transformed to express efficient cellulases. While S.

Association of Cry1Ac toxin resistance in Helicoverpa zea (Boddie) with increased alkaline phosphatase levels in the midgut lumen.

Resistance to Bacillus thuringiensis Cry1Ac toxin was characterized in a population of Helicoverpa zea larvae previously shown not to have an alteration in toxin binding as the primary resistance mechanism to this toxin. Cry1Ac-selected larvae (AR1) were resistant to protoxins and toxins of Cry1Ab, Cry1Ac, and the corresponding modified proteins lacking helix α-1 (Cry1AbMod and Cry1AcMod). When comparing brush border membrane vesicles (BBMVs) prepared from susceptible (LC) and AR1 larval midguts, there were only negligible differences in overall Cry1Ac toxin binding, though AR1 had 18% reversible binding, in contrast to LC, in which all binding was irreversible.

Transcriptome profiling of the intoxication response of Tenebrio molitor larvae to Bacillus thuringiensis Cry3Aa protoxin.

Bacillus thuringiensis (Bt) crystal (Cry) proteins are effective against a select number of insect pests, but improvements are needed to increase efficacy and decrease time to mortality for coleopteran pests. To gain insight into the Bt intoxication process in Coleoptera, we performed RNA-Seq on cDNA generated from the guts of Tenebrio molitor larvae that consumed either a control diet or a diet containing Cry3Aa protoxin. Approximately 134,090 and 124,287 sequence reads from the control and Cry3Aa-treated groups were assembled into 1,318 and 1,140 contigs, respectively.

Identification, cloning, and expression of a GHF9 cellulase from Tribolium castaneum (Coleoptera: Tenebrionidae).

The availability of sequenced insect genomes has allowed for discovery and functional characterization of novel genes and proteins. We report use of the Tribolium castaneum (Herbst) (red flour beetle) genome to identify, clone, express, and characterize a novel endo-β-1,4-glucanase we named TcEG1 (T. castaneum endoglucanase 1).

Characterization of cellulolytic activity from digestive fluids of Dissosteira carolina (Orthoptera: Acrididae).

Previous screening of head-derived and gut fluid extracts of Carolina grasshoppers, Dissosteira carolina (L.) revealed relatively high activity against cellulase substrates when compared to other insect groups. In this work we report on the characterization and identification of enzymes involved in cellulolytic activity in digestive fluids of D.

Prospecting for cellulolytic activity in insect digestive fluids.

Efficient cellulolytic enzymes are needed to degrade recalcitrant plant biomass during ethanol purification and make lignocellulosic biofuels a cost-effective alternative to fossil fuels. Despite the large number of insect species that feed on lignocellulosic material, limited availability of quantitative studies comparing cellulase activity among insect taxa constrains identification of candidate species for more targeted identification of effective cellulolytic systems. We describe quantitative determinations of the cellulolytic activity in gut or head-derived fluids from 68 phytophagous or xylophagous insect species belonging to eight different taxonomic orders.

Identification, RNAi knockdown, and functional analysis of an ejaculate protein that mediates a postmating, prezygotic phenotype in a cricket.

Postmating, prezygotic phenotypes, especially those that underlie reproductive isolation between closely related species, have been a central focus of evolutionary biologists over the past two decades. Such phenotypes are thought to evolve rapidly and be nearly ubiquitous among sexually reproducing eukaryotes where females mate with multiple partners. Because these phenotypes represent interplay between the male ejaculate and female reproductive tract, they are fertile ground for reproductive senescence--as ejaculate composition and female physiology typically change over an individual's life span.

Tribolium castaneum larval gut transcriptome and proteome: A resource for the study of the coleopteran gut.

Tribolium castaneum is an important agricultural pest and an advanced genetic model for coleopteran insects. We have taken advantage of the recently acquired T. castaneum genome to identify T.

A novel Tenebrio molitor cadherin is a functional receptor for Bacillus thuringiensis Cry3Aa toxin.

Cry toxins produced by the bacterium Bacillus thuringiensis are effective biological insecticides. Cadherin-like proteins have been reported as functional Cry1A toxin receptors in Lepidoptera. Here we present data that demonstrate that a coleopteran cadherin is a functional Cry3Aa toxin receptor.

The genome of the model beetle and pest Tribolium castaneum.

Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes.