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Characterization of the juvenile hormone pathway in the viviparous cockroach, Diploptera punctata.

Huang J, Marchal E, Hult EF, Tobe SS - PLoS ONE (2015)

Bottom Line: As a result, oocyte development slowed as a consequence of reduction in JH biosynthesis.Oocyte length, fat body transcription of Vg and ovarian vitellin content significantly decreased.In addition, silencing HMGR and JHAMT resulted in a decrease in the transcript levels of other genes in the pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.

ABSTRACT
Juvenile hormones (JHs) are key regulators of insect development and reproduction. The JH biosynthetic pathway is known to involve 13 discrete enzymatic steps. In the present study, we have characterized the JH biosynthetic pathway in the cockroach Diploptera punctata. The effect of exogenous JH precursors on JH biosynthesis was also determined. Based on sequence similarity, orthologs for the genes directly involved in the pathway were cloned, and their spatial and temporal transcript profiles were determined. The effect of shutting down the JH pathway in adult female cockroaches was studied by knocking down genes encoding HMG-CoA reductase (HMGR) and Juvenile hormone acid methyltransferase (JHAMT). As a result, oocyte development slowed as a consequence of reduction in JH biosynthesis. Oocyte length, fat body transcription of Vg and ovarian vitellin content significantly decreased. In addition, silencing HMGR and JHAMT resulted in a decrease in the transcript levels of other genes in the pathway.

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The effect of JH precursors on JH biosynthesis by CA from mated female D. punctata.JH biosynthesis was determined in CA that were first incubated in medium TC199 (control), and then in medium with JH precursor (treatment). (A) JH precursors stimulate JH biosynthesis by CA from day 7 mated female cockroach, D. punctata. 100μM of JH precursor was added to the medium during the second incubation. (B) The sensitivity of CA to JH precursors during the first gonadotrophic cycle. 40μM farnesol was added during the second incubation. Values represent mean ± SEM (n≥10). Significant differences are indicated ***p < 0.001.
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pone.0117291.g004: The effect of JH precursors on JH biosynthesis by CA from mated female D. punctata.JH biosynthesis was determined in CA that were first incubated in medium TC199 (control), and then in medium with JH precursor (treatment). (A) JH precursors stimulate JH biosynthesis by CA from day 7 mated female cockroach, D. punctata. 100μM of JH precursor was added to the medium during the second incubation. (B) The sensitivity of CA to JH precursors during the first gonadotrophic cycle. 40μM farnesol was added during the second incubation. Values represent mean ± SEM (n≥10). Significant differences are indicated ***p < 0.001.

Mentions: Previous studies suggested that JH synthesis is controlled by the rate of flux of isoprenoids in A. aegypti [11]. To determine the role of other JH precursors in regulating JH biosynthesis, we tested the rate of JH biosynthesis with the addition of JH precursors in the early steps of mevalonate pathway or the addition of farnesol. The addition of acetyl CoA, DPPM or farnesol to the incubation medium had a significant stimulatory effect on JH biosynthesis, whereas MA did not (Fig. 4A). For the first time, we demonstrated that acetyl CoA, as the first precursor in the JH biosynthetic pathway, was able to stimulate JH biosynthesis. The rank order of the stimulatory effects of the different JH precursors on JH biosynthesis is as follows: farnesol > acetyl CoA > DPPM > MA.


Characterization of the juvenile hormone pathway in the viviparous cockroach, Diploptera punctata.

Huang J, Marchal E, Hult EF, Tobe SS - PLoS ONE (2015)

The effect of JH precursors on JH biosynthesis by CA from mated female D. punctata.JH biosynthesis was determined in CA that were first incubated in medium TC199 (control), and then in medium with JH precursor (treatment). (A) JH precursors stimulate JH biosynthesis by CA from day 7 mated female cockroach, D. punctata. 100μM of JH precursor was added to the medium during the second incubation. (B) The sensitivity of CA to JH precursors during the first gonadotrophic cycle. 40μM farnesol was added during the second incubation. Values represent mean ± SEM (n≥10). Significant differences are indicated ***p < 0.001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4338245&req=5

pone.0117291.g004: The effect of JH precursors on JH biosynthesis by CA from mated female D. punctata.JH biosynthesis was determined in CA that were first incubated in medium TC199 (control), and then in medium with JH precursor (treatment). (A) JH precursors stimulate JH biosynthesis by CA from day 7 mated female cockroach, D. punctata. 100μM of JH precursor was added to the medium during the second incubation. (B) The sensitivity of CA to JH precursors during the first gonadotrophic cycle. 40μM farnesol was added during the second incubation. Values represent mean ± SEM (n≥10). Significant differences are indicated ***p < 0.001.
Mentions: Previous studies suggested that JH synthesis is controlled by the rate of flux of isoprenoids in A. aegypti [11]. To determine the role of other JH precursors in regulating JH biosynthesis, we tested the rate of JH biosynthesis with the addition of JH precursors in the early steps of mevalonate pathway or the addition of farnesol. The addition of acetyl CoA, DPPM or farnesol to the incubation medium had a significant stimulatory effect on JH biosynthesis, whereas MA did not (Fig. 4A). For the first time, we demonstrated that acetyl CoA, as the first precursor in the JH biosynthetic pathway, was able to stimulate JH biosynthesis. The rank order of the stimulatory effects of the different JH precursors on JH biosynthesis is as follows: farnesol > acetyl CoA > DPPM > MA.

Bottom Line: As a result, oocyte development slowed as a consequence of reduction in JH biosynthesis.Oocyte length, fat body transcription of Vg and ovarian vitellin content significantly decreased.In addition, silencing HMGR and JHAMT resulted in a decrease in the transcript levels of other genes in the pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.

ABSTRACT
Juvenile hormones (JHs) are key regulators of insect development and reproduction. The JH biosynthetic pathway is known to involve 13 discrete enzymatic steps. In the present study, we have characterized the JH biosynthetic pathway in the cockroach Diploptera punctata. The effect of exogenous JH precursors on JH biosynthesis was also determined. Based on sequence similarity, orthologs for the genes directly involved in the pathway were cloned, and their spatial and temporal transcript profiles were determined. The effect of shutting down the JH pathway in adult female cockroaches was studied by knocking down genes encoding HMG-CoA reductase (HMGR) and Juvenile hormone acid methyltransferase (JHAMT). As a result, oocyte development slowed as a consequence of reduction in JH biosynthesis. Oocyte length, fat body transcription of Vg and ovarian vitellin content significantly decreased. In addition, silencing HMGR and JHAMT resulted in a decrease in the transcript levels of other genes in the pathway.

Show MeSH
Related in: MedlinePlus