Effects of juvenile hormone on gene expression in the pheromone‐producing midgut of the pine engraver beetle, <i>Ips pini</i>

Keeling, Christopher I.; Bearfield, Jeremy C.; Young, Sharon M.; Blomquist, Gary J.; Tittiger, Claus

doi:10.1111/j.1365-2583.2006.00629.x

Cited by 53 publications

(43 citation statements)

References 35 publications

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“…1). In I. pini, the IPPI transcript is up-regulated by both juvenile hormone III and feeding in adults for pheromone biosynthesis (27,28). Dual-function GPPS/FPPS enzymes have been reported previously in other insects (12,29,30).…”

Section: Discussionmentioning

confidence: 80%

Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae , and the role of isoprenyl diphosphate synthases

Keeling

Chiu

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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The mountain pine beetle (Dendroctonus ponderosae Hopkins) is the most destructive pest of western North American pine forests. Adult males produce frontalin, an eight-carbon antiaggregation pheromone, via the mevalonate pathway, as part of several pheromones that initiate and modulate the mass attack of host trees. Frontalin acts as a pheromone, attractant, or kairomone in most Dendroctonus species, other insects, and even elephants. 6-Methylhept-6-en-2-one, a frontalin precursor, is hypothesized to originate from 10-carbon geranyl diphosphate (GPP), 15-carbon farnesyl diphosphate (FPP), or 20-carbon geranylgeranyl diphosphate (GGPP) via a dioxygenase-or cytochrome P450-mediated carboncarbon bond cleavage. To investigate the role of isoprenyl diphosphate synthases in pheromone biosynthesis, we characterized a bifunctional GPP/FPP synthase and a GGPP synthase in the mountain pine beetle. The ratio of GPP to FPP produced by the GPP/FPP synthase was highly dependent on the ratio of the substrates isopentenyl diphosphate and dimethylallyl diphosphate used in the assay. Transcript levels in various tissues and life stages suggested that GGPP rather than GPP or FPP is used as a precursor to frontalin. Reduction of transcript levels by RNA interference of the isoprenyl diphosphate synthases identified GGPP synthase as having the largest effect on frontalin production, suggesting that frontalin is derived from a 20-carbon isoprenoid precursor rather than from the 10-or 15-carbon precursors. (Fig. 1), is an antiaggregation pheromone known to be synthesized de novo via the mevalonate pathway in male midgut tissue (3, 4). Frontalin acts as a pheromone, attractant, or kairomone in most other Dendroctonus species, other insects (5), and even elephants (6, 7) and has been studied in bark beetles for more than 40 y (8). Its biosynthetic precursor, 6-methylhept-6-en-2-one (6MHO), found in both insects and elephants (6, 9), is hypothesized to originate from cleavage of geranyl diphosphate (GPP), farnesyl diphosphate (FPP), or geranylgeranyl diphosphate (GGPP) by a dioxygenase or cytochrome P450 (10). These isoprenyl diphosphates are biosynthesized from the five-carbon precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) by the isoprenyl diphosphate synthases (IDSs) GPP synthase (GPPS), FPP synthase (FPPS), and GGPP synthase (GGPPS). However, it is not known which of these isoprenyl diphosphates is used as a precursor in frontalin biosynthesis.A few IDSs have been characterized in Coleoptera, including an FPPS from the cotton boll weevil (Anthonomus grandis) (11), a GPPS/FPPS from the horseradish leaf beetle (Phaedon cochleariae) (12), and a unique GPPS from the pine engraver beetle (Ips pini) that also produces myrcene (13,14). To assess their importance in pheromone biosynthesis, we identified and functionally characterized two IDSs in MPB. Based on three different lines of evidence, gene-expression patterns of the IDSs, enzyme activity of recombinant proteins, and the frontalin content of dsRNA-trea...

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Section: Discussionmentioning

confidence: 80%

Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae , and the role of isoprenyl diphosphate synthases

Keeling

Chiu

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…The expression of endocrine-linked genes in insect guts has been reported previously. For example, gut expression of mevalonic pathway and P450 genes was previously identified in bark beetles (Keeling et al, 2004(Keeling et al, , 2006, and a putative JH esterase from the beetle P. hilaris was found to have expression in the foregut and midgut (Munyiri and Ishikawa, 2007). Given the importance of chemical communication and trophallaxis in termite society, it is interesting that genes encoding proteins with homology to members of JH biosynthetic and degradation pathways are associated with the termite gut, and that soluble esterases are present in hindgut excretions (Fig.…”

Section: Jh Esterases and Semiochemical/hormone Processingmentioning

confidence: 97%

Characterization of four esterase genes and esterase activity from the gut of the termite Reticulitermes flavipes

Wheeler

Tarver

Coy

et al. 2009

Arch Insect Biochem Physiol

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Four esterase genes and general esterase activity were investigated in the gut of the termite Reticulitermes flavipes. Two genes (RfEst1 and RfEst2) share significant translated identity with a number of insect JH esterases. The two remaining genes (RfEst3 and RfEst4) apparently code for much shorter proteins with similarity to fungal phenolic acid esterases involved in hemicellulose solubilization. All four genes showed consistently high midgut expression. This result was further supported by colorimetric activity assays and Native polyacrylamide gel electrophoresis, which showed significant esterase activity and a number of isoforms in the midgut. The greatest esterase activity and isoform composition were detected when alpha-naphthyl propionate was used as a substrate. Moreover, esterase activity and diverse isoforms were present in gut mitochondrial, microsomal, and cytosolic sub-cellular protein fractions, as well as in the hindgut lumen. These findings reveal an agreement between gut esterase gene expression and activity distributions, and support the idea that R. flavipes gut esterase activity is host (not symbiont)-derived. In addition, these findings support the hypotheses that termite gut esterases may play important roles in lignocellulose digestion and caste differentiation. This study provides important baseline data that will assist ongoing functional-genomic efforts to identify novel genes with roles in semiochemical, hormone, and lignocellulose processing in the termite gut.

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“…Cytosolic actin mRNA, previously used in the Ips genus as a stable endogenous control for transcription experiments (Keeling et al, 2006;Sandstrom et al, 2006), was used as a normalizer to calculate the relative mRNA abundance. As shown in Figure 7, AmyA was expressed at a significantly higher level than AmyB1 in imagoes (Po0.01), larvae (Po0.05) and adult abdomens (Po0.05).…”

Section: The Mrna Expression Of A-amylase Paralogsmentioning

confidence: 99%

Characterization of two closely related α‐amylase paralogs in the bark beetle, Ips typographus (L.)

Viktorinová

Kučerová

Bohmova

et al. 2011

Arch Insect Biochem Physiol

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Ips typographus (L.), the eight-spined spruce bark beetle, causes severe damage throughout Eurasian spruce forests and suitable nuclear markers are needed in order to study its population structure on a genetic level. Two closely related genes encoding a-amylase in I. typographus were characterized and named AmyA and AmyB. Both a-amylase paralogs consisted of six exons and five introns. AmyA encodes a polypeptide of 483 amino acids, whereas AmyB has two alternative transcripts encoding polypeptides of 483 and 370 amino acids. The expression levels of both genes were high during larval stage and adulthood. The AmyB transcripts were absent in the pupal stage. A modification of the allozyme staining method allowed us to detect two clusters of bands on the electrophoretic gel that may correspond to the two a-amylase genes. There was a correlation between the lack of AmyB expression in pupa and the absence of the fast migrating isozyme cluster at this stage, suggesting that the faster migrating isoforms are products of the AmyB gene, whereas the slowly migrating bands are derived from the AmyA. C 2011 Wiley Periodicals, Inc.

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Effects of juvenile hormone on gene expression in the pheromone‐producing midgut of the pine engraver beetle, Ips pini

Cited by 53 publications

References 35 publications

Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae , and the role of isoprenyl diphosphate synthases

Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae , and the role of isoprenyl diphosphate synthases

Characterization of four esterase genes and esterase activity from the gut of the termite Reticulitermes flavipes

Characterization of two closely related α‐amylase paralogs in the bark beetle, Ips typographus (L.)

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