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Claus Tittiger - One of the best experts on this subject based on the ideXlab platform.

  • high substrate specificity of Ipsdienol dehydrogenase idoldh a short chain dehydrogenase from Ips pini bark beetles
    Journal of Biochemistry, 2016
    Co-Authors: Rubi Figueroateran, Gary J Blomquist, Claus Tittiger
    Abstract:

    Ips spp. bark beetles use Ipsdienol, Ipsenol, Ipsdienone and Ipsenone as aggregation pheromone components and pheromone precursors. For Ips pini, the short-chain oxidoreductase Ipsdienol dehydrogenase (IDOLDH) converts (-)-Ipsdienol to Ipsdienone, and thus likely plays a role in determining pheromone composition. In order to further understand the role of IDOLDH in pheromone biosynthesis, we compared IDOLDH to its nearest functionally characterized ortholog with a solved structure: human L-3-hydroxyacyl-CoA dehydrogenase type II/ amyloid-β binding alcohol dehydrogenase (hHADH II/ABAD), and conducted functional assays of recombinant IDOLDH to determine substrate and product ranges and structural characteristics. Although IDOLDH and hHADH II/ABAD had only 35% sequence identity, their predicted tertiary structures had high identity. We found IDOLDH is a functional homo-tetramer. In addition to oxidizing (-)-Ipsdienol, IDOLDH readily converted racemic Ipsenol to Ipsenone, and stereo-specifically reduced both ketones to their corresponding (-)-alcohols. The (+)-enantiomers were never observed as products. Assays with various substrate analogs showed IDOLDH had high substrate specificity for (-)-Ipsdienol, Ipsenol, Ipsenone and Ipsdienone, supporting that IDOLDH functions as a pheromone-biosynthetic enzyme. These results suggest that different IDOLDH orthologs and or activity levels contribute to differences in Ips spp. pheromone composition.

  • functional characterization of myrcene hydroxylases from two geographically distinct Ips pini populations
    Insect Biochemistry and Molecular Biology, 2013
    Co-Authors: Minmin Song, Andrew Gorzalski, Marina Maclean, Sharon Young, Matthew D Ginzel, Gary J Blomquist, Claus Tittiger
    Abstract:

    Abstract Ips pini bark beetles use myrcene hydroxylases to produce the aggregation pheromone component, Ipsdienol, from myrcene. The enantiomeric ratio of pheromonal Ipsdienol is an important prezygotic mating isolation mechanism of I. pini and differs among geographically distinct populations. We explored the substrate and product ranges of myrcene hydroxylases ( CYP9T2 and CYP9T3 ) from reproductively-isolated western and eastern I. pini . The two cytochromes P450 share 94% amino acid identity. CYP9T2 mRNA levels were not induced in adults exposed to myrcene-saturated atmosphere. Functional assays of recombinant enzymes showed both hydroxylated myrcene, (+)- and (−)-α-pinene, 3-carene, and R -(+)-limonene, but not α-phellandrene, (−)-β-pinene, γ-terpinene, or terpinolene, with evidence that CYP9T2 strongly preferred myrcene over other substrates. They differed in the enantiomeric ratios of Ipsdienol produced from myrcene, and in the products resulting from different α-pinene enantiomers. These data provide new information regarding bark beetle pheromone evolution and factors affecting cytochrome P450 structure–function relationshIps.

  • Ipsdienol dehydrogenase idoldh a novel oxidoreductase important for Ips pini pheromone production
    Insect Biochemistry and Molecular Biology, 2012
    Co-Authors: Rubi Figueroateran, Gary J Blomquist, William Welch, Claus Tittiger
    Abstract:

    Abstract Ipsdienone (2-methyl-6-methylene-2,7-octadien-4-one) is an important intermediate in the biosynthesis of pheromonal Ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol) and Ipsenol (2-methyl-6-methylene-7-octen-4-ol) in male pine engraver beetles, Ips pini (Say). A novel Ipsdienol dehydrogenase (IDOLDH) with a pheromone-biosynthetic gene expression pattern was cloned, expressed, functionally characterized, and its cellular localization analyzed. The cDNA has a 762 nt ORF encoding a 253 amino acid predicted translation product of 28 kDa and pI 5.8. The protein has conserved motifs of the Cp2 subfamily of “classical” short-chain dehydrogenases. Transcript levels were highest in pheromone producing tissue: the anterior midgut of fed males. The protein was detected only in male midguts and localized in the cytosolic fraction of midgut cells. Recombinant IDOLDH was produced in Sf9 cells using a baculovirus expression system. Enzyme assays of protein preparations showed IDOLDH used both NAD⁺ and NADP⁺ as coenzymes with specific activities in the nanomole range. Enzyme assays and GC/MS analysis showed that IDOLDH catalyzed the oxidation of racemic Ipsdienol and (4R)-(−)-Ipsdienol to form Ipsdienone, while (4S)-(+)-Ipsdienol was not a substrate. These data strongly implicate IDOLDH as an enzyme involved in terminal pheromone-biosynthetic steps, likely functioning to “tune” Ipsdienol enantiomeric ratios.

  • characterization of Ips pini Ipsdienol dehydrogenase idol dh
    2011
    Co-Authors: Claus Tittiger, William Welch
    Abstract:

    Ipsdienol is an important pheromone component for pine engraver beetle, Ips pini. Ipsdienol is a ten carbon monoterpenoid secondary alcohol and Ipsdienone is the corresponding ketone. We are characterizing the activity of recombinant IDOL DH produced in Sf9 (insect) cells. The enzyme has a high stereospecificity: (-) Ipsdienol was found to be a substrate while (+)-Ipsdienol was neither a substrate nor inhibitor. Closely related monoterpenoids, such as nerol, geraniol, and citral, were neither substrates nor inhibitors. Smaller compounds, such as 2-propanol, also failed to act as an inhibitor or substrate. This indicates the binding site of this enzyme is highly selective. Gailure to act as an inhibitor most likely indicates these compounds bind weakly. (-)-Ipsdienol, Ipsdienone, Ipsenol, and Ipsenone are substrates. Interestingly, menthone, a cyclic analog of Ipsdienol, was found to have substrate activity. Results from gel permeation chromatography shows the active conformation of IDOL DH is a tetramer. Together these results suggest IDOLDH has a highly specific substrate binding site, and is a key component in pheromone biosynthesis. My work indicates this enzyme evolved to be a specific catalyst for interconversion. This is supported by the following observations: •IDOL DH has a highly specific substrate binding site. Related terpenoids, such as nerol, geraniol, and citral, were not substrates nor inhibitors for IDOL DH. Smaller compounds, such as 2-propanol, failed to act as an inhibitor or substrate •IDOL DH has a high stereospecificity; (-) Ipsdienol was found to be a substrate while (+) Ipsdienol was neither a substrate nor inhibitor. •Menthone, a cyclic terpenoid, is a substrate but not an inhibitor. This shows the importance of the catalytic substrate binding site of this enzyme. The structures of other related terpenoids were flexible; however, menthone is a rigid structure due to its cyclic conformation. •These activities are only found in infected cells •The active conformation of IDOL DH is a tetramer. Figure 4. Compounds tested. The boxed compounds are known substrates

  • isolation endocrine regulation and transcript distribution of a putative primary jh responsive gene from the pine engraver Ips pini coleoptera scolytidae
    Insect Biochemistry and Molecular Biology, 2008
    Co-Authors: Jeremy C Bearfield, Sharon Young, Gary J Blomquist, Christopher I Keeling, Claus Tittiger
    Abstract:

    Abstract We isolated a cDNA of unknown function from a juvenile hormone III (JH III)-treated male midgut cDNA library prepared from the pine engraver beetle, Ips pini , and examined its genomic structure. The gene, tentatively named “ Ipi10G08 ”, encoded a 410 amino acid translation product that shared 26–37% identity with unannotated matches from several insects. Semi-quantitative RT-PCR analysis of Ipi10G08 following application of a 10 μg dose of JH III demonstrated an early induction for both male and female beetles, with transcripts being detectable after 45 min. An expression profile of male midgut tissue indicated Ipi10G08 transcript levels reach a maximum induction of ∼22.5-fold control levels at 4 h post-treatment. Tissue distribution studies displayed a large induction of Ipi10G08 mRNA in the alimentary canal of JH III-treated beetles, especially in males. A dose curve from both sexes suggested there may be a difference in the ability to respond to lower levels of JH III and immunoblot analysis indicated that although JH III highly induces transcript levels in females, protein levels are not similarly induced, while protein levels are induced in males. Ipi10G08 is likely a primary JH response gene and may provide insight into how this hormone exerts its actions.

Kenneth F. Raffa - One of the best experts on this subject based on the ideXlab platform.

  • Kairomonal range of generalist predators in specialized habitats: responses to multiple phloeophagous species emitting pheromones vs. host odors
    Entomologia Experimentalis Et Applicata, 2020
    Co-Authors: Nadir Erbilgin, Kenneth F. Raffa
    Abstract:

    We evaluated responses of the predominant predators of pheromone-producing bark beetles (Coleoptera: Scolytidae) to chemical cues associated with other phloeophagous species that colonize the same trees. This study considered the range of chemical signals exploited by a category of predators that may be viewed either as specialists, because they feed almost exclusively within trees killed by bark beetles, or as generalists, because they feed on a diverse fauna of primary and secondary insects within this habitat. It also evaluated one aspect of a broader model of predator-prey coevolution, that proposes altered semiochemistry as a source of partial escape from predators that exploit kairomones. The predators, Thanasimus dubius(F.) (Coleoptera: Cleridae) and Platysoma cylindrica (Paykull) (Coleoptera: Histeridae), were attracted to cues associated with feeding on bark-phloem disks by two scolytids that produce adult pheromones, Ips pini (Say) and Ips grandicollis (Eichhoff). These predators were not attracted to beetles that feed on lower stems or roots and are not known to produce adult pheromones, Dendroctonus valensLeConte, Hylastes porculusErickson (Coleoptera: Scolytidae), and Hylobius pales (Herbst) (Coleoptera: Curculionidae). The predator Tenebroides collaris (Sturm) (Coleoptera: Trogositidae) was attracted to I. pini and I. grandicollis ,a nd also toD. valens, H. porculus ,a ndH. pales. Ips pini was attracted to conspecifics only, but I. grandicollis was attracted both to its conspecifics and to volatiles associated with feeding lower stem and root insects. Lower stem and root insects were not or only weakly attracted to cues associated with their conspecifics. These results are consistent with a dynamic coevolved interaction between T. dubiusand P. cylindrica and Ips spp.

  • behaviours of phoretic mites acari associated with Ips pini and Ips grandicollis coleoptera curculionidae during host tree colonization
    Agricultural and Forest Entomology, 2016
    Co-Authors: Jesse A Pfammatter, Kareem M Malas, Kenneth F. Raffa
    Abstract:

    Studies on interactions between bark beetles and phoretic mites have focused largely on dispersal life stages. However, many of these interactions occur within trees, where beetles and mites develop. Within-tree interactions are potentially important to beetle and mite reproduction, as well as beetle–mite phoretic pairings. We performed experiments aiming to characterize the behaviours of mites associated with Ips pini (Say) and Ips grandicollis (Eichoff) during nondispersal life stages. Mites are highly specific in the location on which they attach to beetles. Detachment from beetles is elicited by cues associated with both beetle vectors and tree hosts. Beetle condition can trigger rapid mite departure and Iponemus confusus Lindquist detach more rapidly from beetles colonizing tissue amended with the host tree secondary compound α-pinene than in un-amended tissue. Within-plant movement by detached mites is elicited by host plant volatiles. In olfactometer assays, Dendrolaelaps quadrisetus (Berlese) preferred volatiles from beetle-infested phloem over fresh phloem and blank controls. Within host plant tissue, fungal symbionts of beetles provide a resource for mites. Histiogaster arborsignis Berlese fed and reproduced more successfully on Pinus resinosa (Ait) phloem inoculated with the symbiotic fungus Ophiostoma Ips (Rumbold) than on phloem with the opportunistic fungus Aspergillus fumigatus or blank controls.

  • mites phoretic on Ips pini coleoptera curculionidae scolytinae in wisconsin red pine stands
    Annals of The Entomological Society of America, 2013
    Co-Authors: Jesse A Pfammatter, John C Moser, Kenneth F. Raffa
    Abstract:

    ABSTRACT We sampled the bark beetle Ips pini (Say) in Wisconsin red pine stands to describe its phoretic mite community. Nearly 78% of adult beetles carried phoretic mites, with an average of 12.78 ± 0.76 individuals and 1.69 ± 0.05 species per beetle. Phoretic mites from flying beetles represented over 13 families. Five species of mites showed relatively close associations, being present on at least 10% of adult beetles. The most common mite species included one from each of the major guilds on bark beetles, the scavenger/fungivore Histiostoma spp. (41.5% of beetles), the egg predator Iponemus confusus (Lindquist) (41.1% of beetles) and the nematode predator Dendrobebps quadrisetus (Berlese) (32.8% of beetles). Beetles in northern Wisconsin had more diverse phoretic mite communities than those in central or southern Wisconsin. Beetles collected late in the season (July-August) carried more individuals and species of mites than those collected early in the season (May-June). The method we used to collect ...

  • assemblage of hymenoptera arriving at logs colonized by Ips pini coleoptera curculionidae scolytinae and its microbial symbionts in western montana
    Canadian Entomologist, 2009
    Co-Authors: Celia K Boone, Steven J Krauth, Kenneth F. Raffa
    Abstract:

    Colonization of a tree by bark beetles and their symbionts creates a new habitat for a diverse assemblage of arthropods, including competing herbivores, xylophages, fungivores, saprophages, predators, and parasitoids. Understanding these assemblages is important for evalu- ating nontarget effects of various management tactics and for subsequently evaluating how changes in climate, the presence of invasive species, and altered forestry practices and land-use tenure may affect biodiversity. We characterized the assemblage of hymenopterans attracted to logs of ponderosa pine (Pinus ponderosa C. Lawson (Pinaceae)) colonized by the bark beetle Ips pini (Say) and its microbial symbionts. In one experiment, the composition and relative abun- dances of species arriving at hosts colonized by I. pini, and possible sources of attraction, were determined. Treatments consisted of a log containing I. pini with its natural complement of mi- croorganisms, a log alone, and a blank control. A second experiment was carried out to deter- mine whether or not Hymenoptera were attracted to microbial symbionts of I. pini. Treatments consisted of a blank control, a log alone, a log containing I. pini with its natural complement of microorganisms, either Ophiostoma Ips, Burkholderia sp., or Pichia scolyti, and a log inoculated with a combination of these three microorganisms. Over 2 years, 5163 Hymenoptera were cap- tured, of which over 98% were parasitoids. Braconidae, Platygastridae, Encyrtidae, Pteromalidae, and Ichneumonidae were the most abundant. Seven known species of bark beetle parasitoids (all Pteromalidae) were captured. However, parasitoids of Diptera, Lepidoptera, Hymenoptera, and non-wood-boring Coleoptera were also common. Nineteen species showed preferential attraction to host plants infested with I. pini and its complement of microorganisms, host plants inoculated with I. pini microbial symbionts, or host plants alone. Interestingly, many of these species were parasitoids of phytophagous, fungivorous, and saprophytic insects rather than of bark beetles themselves. These results suggest that a diverse assemblage of natural enemies that attack vari- ous feeding guilds within a common habitat exploit common olfactory cues. 199 Resume—La colonisation d'un arbre par les scolytes et leurs symbiontes cree un nouvel habitat pour divers peuplements d'arthropodes, en particulier des herbivores competiteurs, des xylopha- ges, des mycetophages, des saprophages, des predateurs et des parasitoides. Il est important de comprendre ces peuplements pour pouvoir evaluer les effets non cibles des diverses tactiques de gestion et pour ensuite determiner de quelle maniere le changement climatique, la presence d' es- peces envahissantes, ainsi que les changements dans les pratiques forestieres et l'utilisation des terres, peuvent affecter la biodiversite. Nous decrivons le peuplement d'hymenopteres attires par les troncs de pin ponderosa (Pinus ponderosa C. Lawson (Pinaceae)) colonises par le scolyte du

  • composition of the bacterial community in the gut of the pine engraver Ips pini say coleoptera colonizing red pine
    Symbiosis, 2007
    Co-Authors: Kier D Klepzig, Italo Delalibera, Archana Vasanthakumar, Benjamin J Burwitz, Patrick D Schloss, Jo Handelsman, Kenneth F. Raffa
    Abstract:

    The gut bacterial community of a bark beetle, the pine engraver Ips pini (Say), was characterized using culture-dependent and culture-independent methods. Bacteria from individual guts of larvae, pupae and adults were cultured and DNA was extracted from samples of pooled larval guts. Analysis of 16S rRNA gene sequences amplified directly from the gut community suggests that the gut bacterial communities associated with I. pini are relatively simple, compared to many other systems. Six bacterial genera from four classes were detected by culturing gut bacteria from larvae, pupae and adults. Two genera, Pantoea and Stenotrophomonas (y-Proteobacteria) were found in all life stages of I. pini, consistently in larvae and adults, and less commonly in pupae. Sequences that affiliate with the Enterobactereaceae of the γ-Proteobacteria were found in 95% of the clones sampled. The Enterobactereaceae genera, Pantoea and Erwinia, accounted for 88% of all clone sequences. These results are consistent with previous work indicating that another bark beetle, the southern pine beetle, Dendroctonus frontalis Zimmerman, also has a relatively simple gut flora, compared with wood colonizing insects such as wood borers and termites. The composition and abundance of bacteria associated with different life stages of I. pini are possibly associated with specific functions of the gut bacterial communities of larvae, pupae, and adults.

J H Borden - One of the best experts on this subject based on the ideXlab platform.

  • 1 octen 3 ol is repellent to Ips pini coleoptera curculionidae scolytinae in the midwestern united states
    Canadian Entomologist, 2009
    Co-Authors: Therese M Poland, Deepa S Pureswaran, Tina M Ciaramitaro, J H Borden
    Abstract:

    Abstract In field experiments at three sites in Michigan and Ohio we tested the activity of 1-octen-3-ol in combination with Ipsdienol, the aggregation pheromone of the pine engraver, Ips pini (Say). When 1-octen-3-ol was added to funnel traps baited with Ipsdienol, significantly fewer beetles of either sex were captured than in traps baited with Ipsdienol alone. This result suggests that the compound is potentially repellent and interrupts the response of beetles to their aggregation pheromone, and is consistent with previous reports of its inhibition of aggregation behaviour in other bark beetles.

  • dose dependent pheromone responses of Ips pini orthotomicus latidens coleoptera scolytidae and associates in stands of lodgepole pine
    Environmental Entomology, 2005
    Co-Authors: Daniel R Miller, J H Borden, Staffan B Lindgren
    Abstract:

    Abstract We conducted four behavioral choice tests in stands of mature lodgepole pine in British Columbia, from 1988 to 1991, to determine the dose-dependent responses of Orthotomicus latidens (LeConte) and Ips pini (Say) to their respective pheromones. Dose-dependent responses were exhibited by I. pini to (±)-Ipsdienol and lanierone, with trap catches directly proportional to pheromone release rates. We found differences in sex ratio of I. pini in their responses to Ipsdienol but not lanierone. There was no dose-dependent response exhibited by O. latidens to its pheromone, (±)-Ipsenol, with or without the presence of the host kairomone, (−)-β-phellandrene. The bark beetle predator, Enoclerus lecontei (Wolcott), showed a dose-dependent response to lanierone. Thanasimus undatulus (Say) was attracted to Ipsenol in a dose-dependent fashion only when traps were also baited with β-phellandrene. Neither T. undatulus nor E. sphegeus (F.) exhibited dose-dependent responses to Ipsdienol.

  • responses of Ips pini say pityogenes knechteli swaine and associated beetles coleoptera to host monoterpenes in stands of lodgepole pine
    Journal of Entomological Science, 2003
    Co-Authors: Daniel R Miller, J H Borden
    Abstract:

    We conducted seven experiments in stands of mature lodgepole pine in southern British Columbia to elucidate the role of host volatiles in the semiochemical ecology of the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae), with particular reference to the behavioral responses of predators and competing species of bark beetles. Our results demonstrated that the attraction of Ips pini and the bark beetle predators Lasconofus complex LeConte (Colydi- idae), Thanasimus undafulus (Say) (Cleridae) and a Corticeus sp. (Tenebrionidae) were in- creased by 3-carene. In contrast, attraction of the bark beetle Pityogenes knecbfeli Swaine (Scolytidae) to Ipsdienol was interrupted by 3-carene and a-pinene. Attraction of L. complex to Ipsdienol was increased by r-terpinene, a compound attractive to the mountain pine beetle, Dendroctonus ponderosae Hopkins (Scolytidae). Terpinolene interrupted the attraction of 1. pini

  • response of the pine engraver Ips pini say coleoptera scolytidae to conophthorin and other angiosperm bark volatiles in the avoidance of non hosts
    Agricultural and Forest Entomology, 2001
    Co-Authors: Dezene P W Huber, J H Borden, Michael Stastny
    Abstract:

    Seventeen non-host angiosperm bark volatiles, seven of which are antennally active to Ips pini (Say), the pine engraver (PE), were tested for their ability to disrupt the response of the PE to pheromone-baited traps. 2 Four green leaf volatiles (GLVs) were tested (1-hexanol (Z)-3-hexen-1-ol, hexanal, and (E)-2-hexenal). None had any disruptive effect singly, as a group or in all possible blends based on functional groups, despite the fact that the two aldehydes were antennally active. These compounds may have, in some instances, actually masked the disruptive effect of other compounds. The PE thus differs in its response from other Scolytidae, including other Ips spp. 3 Eight non-host volatiles that were antennally active to other bark beetles, but not to PEs, had no disruptive effect, validating the use of coupled gas chromatographic-electroantennographic detection analyses to detect compounds with potential behavioural activity. 4 The bicyclic spiroacetal conophthorin, (E)-7-methyl-1,6-dioxaspiro(4.5)decane, was disruptive when tested alone. When blends of two aldehydes (salicylaldehyde and nonanal) plus an alcohol and a phenol (benzyl alcohol and guaiacol) were combined with conophthorin, an enhanced disruptive effect was revealed. No sin- gle compound, other than conophthorin, disrupted the pheromone-positive response and no blend that did not contain conophthorin was consistently disrup- tive to both sexes. Conophthorin seems to be a critical component in the non-host angiosperm message for I. pini during its host selection phase. 5 Combination of the repellent synomones, verbenone and Ipsenol, with the five disruptive non-host volatiles may provide a potent treatment to protect trees, logs or stands from attack by the PE.

  • dynamics of pheromone production and communication in the mountain pine beetle dendroctonus ponderosae hopkins and the pine engraver Ips pini say coleoptera scolytidae
    Chemoecology, 2000
    Co-Authors: Deepa S Pureswaran, J H Borden, Regine Gries, H D Pierce
    Abstract:

    The mountain pine beetle, Dendroctonus ponderosae Hopkins, and the pine engraver, Ips pini (Say), often co-exist in lodgepole pine, Pinus contorta var. latifolia Engelmann. Intra- and interspecific semiochemical communication occurs in both species and their complete semiochemical repertoire and precise dynamics of pheromone production have not been elucidated. Porapak-Q extracts of captured volatiles from beetles of each species aerated at different attack phases (freshly emerged, pioneer sex alone in the log and both sexes paired in new galleries), followed by gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectroscopic analyses identified 17 compounds (seven compounds common to both species, six present in D. ponderosae and four present in I. pini) that excited the antennae of either or both species. Seven compounds for D. ponderosae and nine for I. pini had not been assessed for behavioural activity. In field trapping experiments, 2-phenylethanol produced by both species inhibited the response of D. ponderosae to its aggregation pheromones. exo- and endo-Brevicomin produced by D. ponderosae significantly decreased the response of I. pini to its aggregation pheromone Ipsdienol. Nonanal, a ubiquitous compound found in the volatiles of lodgepole pine, various nonhosts and in both beetle species deterred the response of I. pini to Ipsdienol. The occurrence of cis-verbenol, trans-verbenol and verbenone in emergent I. pini, and verbenone and 2-phenylethanol in emergent D. ponderosae suggests that these compounds may inhibit aggregation and induce dispersal following emergence. Termination of aggregation in D. ponderosae appears to depend on the production of frontalin in combination with changes in the relative ratios of verbenone, exo-brevicomin, trans-verbenol and 2-phenylethanol. In I. pini, the cessation of Ipsdienol production by males is probably the main factor in terminating aggregation.

Gary J Blomquist - One of the best experts on this subject based on the ideXlab platform.

  • high substrate specificity of Ipsdienol dehydrogenase idoldh a short chain dehydrogenase from Ips pini bark beetles
    Journal of Biochemistry, 2016
    Co-Authors: Rubi Figueroateran, Gary J Blomquist, Claus Tittiger
    Abstract:

    Ips spp. bark beetles use Ipsdienol, Ipsenol, Ipsdienone and Ipsenone as aggregation pheromone components and pheromone precursors. For Ips pini, the short-chain oxidoreductase Ipsdienol dehydrogenase (IDOLDH) converts (-)-Ipsdienol to Ipsdienone, and thus likely plays a role in determining pheromone composition. In order to further understand the role of IDOLDH in pheromone biosynthesis, we compared IDOLDH to its nearest functionally characterized ortholog with a solved structure: human L-3-hydroxyacyl-CoA dehydrogenase type II/ amyloid-β binding alcohol dehydrogenase (hHADH II/ABAD), and conducted functional assays of recombinant IDOLDH to determine substrate and product ranges and structural characteristics. Although IDOLDH and hHADH II/ABAD had only 35% sequence identity, their predicted tertiary structures had high identity. We found IDOLDH is a functional homo-tetramer. In addition to oxidizing (-)-Ipsdienol, IDOLDH readily converted racemic Ipsenol to Ipsenone, and stereo-specifically reduced both ketones to their corresponding (-)-alcohols. The (+)-enantiomers were never observed as products. Assays with various substrate analogs showed IDOLDH had high substrate specificity for (-)-Ipsdienol, Ipsenol, Ipsenone and Ipsdienone, supporting that IDOLDH functions as a pheromone-biosynthetic enzyme. These results suggest that different IDOLDH orthologs and or activity levels contribute to differences in Ips spp. pheromone composition.

  • functional characterization of myrcene hydroxylases from two geographically distinct Ips pini populations
    Insect Biochemistry and Molecular Biology, 2013
    Co-Authors: Minmin Song, Andrew Gorzalski, Marina Maclean, Sharon Young, Matthew D Ginzel, Gary J Blomquist, Claus Tittiger
    Abstract:

    Abstract Ips pini bark beetles use myrcene hydroxylases to produce the aggregation pheromone component, Ipsdienol, from myrcene. The enantiomeric ratio of pheromonal Ipsdienol is an important prezygotic mating isolation mechanism of I. pini and differs among geographically distinct populations. We explored the substrate and product ranges of myrcene hydroxylases ( CYP9T2 and CYP9T3 ) from reproductively-isolated western and eastern I. pini . The two cytochromes P450 share 94% amino acid identity. CYP9T2 mRNA levels were not induced in adults exposed to myrcene-saturated atmosphere. Functional assays of recombinant enzymes showed both hydroxylated myrcene, (+)- and (−)-α-pinene, 3-carene, and R -(+)-limonene, but not α-phellandrene, (−)-β-pinene, γ-terpinene, or terpinolene, with evidence that CYP9T2 strongly preferred myrcene over other substrates. They differed in the enantiomeric ratios of Ipsdienol produced from myrcene, and in the products resulting from different α-pinene enantiomers. These data provide new information regarding bark beetle pheromone evolution and factors affecting cytochrome P450 structure–function relationshIps.

  • Ipsdienol dehydrogenase idoldh a novel oxidoreductase important for Ips pini pheromone production
    Insect Biochemistry and Molecular Biology, 2012
    Co-Authors: Rubi Figueroateran, Gary J Blomquist, William Welch, Claus Tittiger
    Abstract:

    Abstract Ipsdienone (2-methyl-6-methylene-2,7-octadien-4-one) is an important intermediate in the biosynthesis of pheromonal Ipsdienol (2-methyl-6-methylene-2,7-octadien-4-ol) and Ipsenol (2-methyl-6-methylene-7-octen-4-ol) in male pine engraver beetles, Ips pini (Say). A novel Ipsdienol dehydrogenase (IDOLDH) with a pheromone-biosynthetic gene expression pattern was cloned, expressed, functionally characterized, and its cellular localization analyzed. The cDNA has a 762 nt ORF encoding a 253 amino acid predicted translation product of 28 kDa and pI 5.8. The protein has conserved motifs of the Cp2 subfamily of “classical” short-chain dehydrogenases. Transcript levels were highest in pheromone producing tissue: the anterior midgut of fed males. The protein was detected only in male midguts and localized in the cytosolic fraction of midgut cells. Recombinant IDOLDH was produced in Sf9 cells using a baculovirus expression system. Enzyme assays of protein preparations showed IDOLDH used both NAD⁺ and NADP⁺ as coenzymes with specific activities in the nanomole range. Enzyme assays and GC/MS analysis showed that IDOLDH catalyzed the oxidation of racemic Ipsdienol and (4R)-(−)-Ipsdienol to form Ipsdienone, while (4S)-(+)-Ipsdienol was not a substrate. These data strongly implicate IDOLDH as an enzyme involved in terminal pheromone-biosynthetic steps, likely functioning to “tune” Ipsdienol enantiomeric ratios.

  • isolation endocrine regulation and transcript distribution of a putative primary jh responsive gene from the pine engraver Ips pini coleoptera scolytidae
    Insect Biochemistry and Molecular Biology, 2008
    Co-Authors: Jeremy C Bearfield, Sharon Young, Gary J Blomquist, Christopher I Keeling, Claus Tittiger
    Abstract:

    Abstract We isolated a cDNA of unknown function from a juvenile hormone III (JH III)-treated male midgut cDNA library prepared from the pine engraver beetle, Ips pini , and examined its genomic structure. The gene, tentatively named “ Ipi10G08 ”, encoded a 410 amino acid translation product that shared 26–37% identity with unannotated matches from several insects. Semi-quantitative RT-PCR analysis of Ipi10G08 following application of a 10 μg dose of JH III demonstrated an early induction for both male and female beetles, with transcripts being detectable after 45 min. An expression profile of male midgut tissue indicated Ipi10G08 transcript levels reach a maximum induction of ∼22.5-fold control levels at 4 h post-treatment. Tissue distribution studies displayed a large induction of Ipi10G08 mRNA in the alimentary canal of JH III-treated beetles, especially in males. A dose curve from both sexes suggested there may be a difference in the ability to respond to lower levels of JH III and immunoblot analysis indicated that although JH III highly induces transcript levels in females, protein levels are not similarly induced, while protein levels are induced in males. Ipi10G08 is likely a primary JH response gene and may provide insight into how this hormone exerts its actions.

  • antennally mediated negative feedback regulation of pheromone production in the pine engraver beetle Ips pini
    Naturwissenschaften, 2006
    Co-Authors: Matthew D Ginzel, Gary J Blomquist, Jeremy C Bearfield, Christopher I Keeling, Colin C Mccormack, Claus Tittiger
    Abstract:

    Bark beetles use monoterpenoid aggregation pheromones to coordinate host colonization and mating. These chemical signals are produced de novo in midgut cells via the mevalonate pathway, and pheromone production may be regulated by a negative feedback system mediated through the antennae. In this study, we explored the effect of antennectomy on pheromone production and transcript levels of key mevalonate pathway genes in juvenile hormone III-treated male pine engraver beetles, Ips pini (Say). Antennectomized males produced significantly greater amounts of pheromone than podectomized males and those with intact antennae. Likewise, mRNA levels of three mevalonate pathway genes important in pheromone biosynthesis were measured by quantitative real-time PCR and found to be induced to a greater extent with antennectomy, suggesting a transcriptional regulation of pheromone production.

Daniel R Miller - One of the best experts on this subject based on the ideXlab platform.

  • dose dependent pheromone responses of Ips pini orthotomicus latidens coleoptera scolytidae and associates in stands of lodgepole pine
    Environmental Entomology, 2005
    Co-Authors: Daniel R Miller, J H Borden, Staffan B Lindgren
    Abstract:

    Abstract We conducted four behavioral choice tests in stands of mature lodgepole pine in British Columbia, from 1988 to 1991, to determine the dose-dependent responses of Orthotomicus latidens (LeConte) and Ips pini (Say) to their respective pheromones. Dose-dependent responses were exhibited by I. pini to (±)-Ipsdienol and lanierone, with trap catches directly proportional to pheromone release rates. We found differences in sex ratio of I. pini in their responses to Ipsdienol but not lanierone. There was no dose-dependent response exhibited by O. latidens to its pheromone, (±)-Ipsenol, with or without the presence of the host kairomone, (−)-β-phellandrene. The bark beetle predator, Enoclerus lecontei (Wolcott), showed a dose-dependent response to lanierone. Thanasimus undatulus (Say) was attracted to Ipsenol in a dose-dependent fashion only when traps were also baited with β-phellandrene. Neither T. undatulus nor E. sphegeus (F.) exhibited dose-dependent responses to Ipsdienol.

  • responses of Ips pini say pityogenes knechteli swaine and associated beetles coleoptera to host monoterpenes in stands of lodgepole pine
    Journal of Entomological Science, 2003
    Co-Authors: Daniel R Miller, J H Borden
    Abstract:

    We conducted seven experiments in stands of mature lodgepole pine in southern British Columbia to elucidate the role of host volatiles in the semiochemical ecology of the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae), with particular reference to the behavioral responses of predators and competing species of bark beetles. Our results demonstrated that the attraction of Ips pini and the bark beetle predators Lasconofus complex LeConte (Colydi- idae), Thanasimus undafulus (Say) (Cleridae) and a Corticeus sp. (Tenebrionidae) were in- creased by 3-carene. In contrast, attraction of the bark beetle Pityogenes knecbfeli Swaine (Scolytidae) to Ipsdienol was interrupted by 3-carene and a-pinene. Attraction of L. complex to Ipsdienol was increased by r-terpinene, a compound attractive to the mountain pine beetle, Dendroctonus ponderosae Hopkins (Scolytidae). Terpinolene interrupted the attraction of 1. pini

  • frontalin interrupts attraction of Ips pini coleoptera scolytidae to Ipsdienol
    Canadian Entomologist, 2001
    Co-Authors: Daniel R Miller
    Abstract:

    The pine engraver, Ips pini (Say), breeds in the phloem tissue of dead, dying, or downed pines, occasionally attacking standing live trees when populations build up to significant levels following logging activities or infestations by the mountain pine beetle, Dendroctonus ponderosae Hopkins (Furniss and Carolin 1980). In British Columbia, I. pini uses Ipsdienol as an aggregation pheromone to facilitate large aggregations of mated beetles and breeding galleries (Miller et al. 1996). The aggregation pheromones, exo -brevicomin and cis - and trans -verbenol, used by D. ponderosae (Borden et al. 1987; Miller and Lafontaine 1991) interrupt attraction of I. pini to Ipsdienol (Miller 1991). Another semiochemical, frontalin, is used by D. ponderosae as a multifunctional pheromone (Borden et al. 1987), enhancing attraction of beetles at low release rates and interrupting attraction at high release rates. I tested the effect of frontalin, over a broad range of release rates, on the attraction of I. pini to Ipsdienol-baited traps.

  • vertical displacement of Ips latidens and Ips pini coleoptera scolytidae by semiochemical interruption
    Canadian Entomologist, 2000
    Co-Authors: Daniel R Miller
    Abstract:

    Nous avons teste les effets d'inhibiteurs semiochimiques chez Ips latidens (LeConte) et Ips pini (Say) en utilisant des arbres artificiels (arbres-pieges) composes de sept pieges Lindgren a plusieurs entonnoirs suspendus verticalement sur une echelle de corde. Le S-(+)-Ipsdienol a reduit le nombre de I. latidens captures dans des pieges a entonnoirs garnis de (±)-Ipsenol comparativement au nombre capture dans les pieges a entonnoirs installes immediatement au-dessus et dans les arbres-pieges temoins. La combinaison de (±)-exo-brevicomine et de cis- et trans-verbenol a eu pour effet de reduire le nombre d'I. pini captures dans les pieges a entonnoirs garnis de (±)-Ipsdienol comparativement au nombre capture dans les pieges temoins situes immediatement au-dessus et dans les arbres-pieges temoins. Ces resultats justifient le recours a des tactiques d'amenagement semiochimiques qui utilisent une substance inhibitrice ponctuelle placee a la base d'un arbre, mais soulignent l'importance de tenir compte des limites de l'efficacite de la methode et de ses effets sur le comportement.

  • pheromone interruption of pine engraver Ips pini by pheromones of mountain pine beetle dendroctonus ponderosae coleoptera scolytidae
    Journal of the Entomological Society of British Columbia, 2000
    Co-Authors: Daniel R Miller, J H Borden
    Abstract:

    The effect of pheromones of Dendroctonus ponderosae Hopkins on the attraction of Ips pini (Say) to its pheromone, Ipsdienol, was investigated in stands of lodgepole pine. The mixture of cis- and trans-verbenol significantly reduced catches of I. pini in traps baited with Ipsdienol at three locations in British Columbia. exo-Brevicomin had no effect on catches of I. pini, irrespective of the enantiomeric composition of exobrevicomin. Ipsdienol did not significantly reduce the attraction of D. ponderosae to traps baited with cis - and trans-verbenol, and (±)-exo-brevicomin. Key Words: Coleoptera; Scolytidae; Ips pini; Dendroctonus ponderosae; pheromone interruption; synomone; exo-brevicomin; cis-verbenol; trans-verbenol; Ipsdienol