Hillyer Lab News
Hillyer Lab News
Article detailing the cardioacceleratory function of mosquito CCAP is published in The Journal of Experimental Biology
Wednesday, January 30, 2013
An article detailing the function of the neurohormone crustacean cardioactive peptide (CCAP) on the mosquito Anopheles gambiae was published today in The Journal of Experimental Biology. In this study we used molecular and imaging methodologies to show that:
1.Anopheles gambiae CCAP is encoded by a single gene, which produces a neuropeptide that shares 100% amino acid identity with all sequenced CCAP peptides, except for Daphnia pulex.
2.Expression of CCAP and the CCAP receptor displays a bimodal distribution, with peak mRNA levels in second instar larvae and pupae.
3.Augmenting CCAP levels in the hemocoel of adult mosquitoes increases heart contraction rates and hemolymph flow velocity.
4.Reducing CCAP mRNA levels by RNA interference decreases heart contraction rates.
Article Citation:
Estévez-Lao, T.Y, D.S. Boyce, H.-W. Honegger, and J.F. Hillyer. 2013. Cardioacceleratory function of the neurohormone CCAP in the mosquito Anopheles gambiae. Journal of Experimental Biology. 216(4):601-613. (PubMed) (Article on JEB website) (Story in Inside JEB).
Effect of CCAP on the mosquito heart contraction rate
Article abstract:
Crustacean cardioactive peptide (CCAP) is a highly conserved arthropod neurohormone that is involved in ecdysis, hormone release and the modulation of muscle contractions. Here, we determined the CCAP gene structure in the malaria mosquito Anopheles gambiae, assessed the developmental expression of CCAP and its receptor and determined the role that CCAP plays in regulating mosquito cardiac function. RACE sequencing revealed that the A. gambiae CCAP gene encodes a neuropeptide that shares 100% amino acid identity with all sequenced CCAP peptides, with the exception of Daphnia pulex. Quantitative RT-PCR showed that expression of CCAP and the CCAP receptor displays a bimodal distribution, with peak mRNA levels in second instar larvae and pupae. Injection of CCAP revealed that augmenting hemocoelic CCAP levels in adult mosquitoes increases the anterograde and retrograde heart contraction rates by up to 28%, and increases intracardiac hemolymph flow velocities by up to 33%. Partial CCAP knockdown by RNAi had the opposite effect, decreasing the mosquito heart rate by 6%. Quantitative RT-PCR experiments showed that CCAP mRNA is enriched in the head region, and immunohistochemical experiments in newly eclosed mosquitoes detected CCAP in abdominal neurons and projections, some of which innervated the heart, but failed to detect CCAP in the abdomens of older mosquitoes. Instead, in older mosquitoes CCAP was detected in the pars lateralis, the subesophageal ganglion and the corpora cardiaca. In conclusion, CCAP has a potent effect on mosquito circulatory physiology, and thus heart physiology in this dipteran insect is under partial neuronal control.
“The Journal of Experimental Biology (JEB) is the leading journal in comparative animal physiology and is published by The Company of Biologists, a not-for-profit charitable organization run by biologists for the benefit of the biological community.”