Title: Capa-Gene Products in the Haematophagous Sandfly Phlebotomus Papatasi (Scopoli) - Vector for Leishmaniasis Disease Authors
Submitted to: Peptides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2012
Publication Date: March 15, 2013
Citation: Predel, R., Neupert, S., Russell, W.K., Hauser, F., Russell, D.H., Li, A.Y., Nachman, R.J. 2013. CAPA-gene products in the haematophagous sandfly Phlebotomus papatasi (Scopoli) - Vector for leishmaniasis disease. Peptides. 41:2-7. Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neuropeptides hold little promise as pest control agents because they can be degraded in the target pest. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. We report on the identification of four neuropeptide hormones from the central nervous system of the tiny sandfly, a vector of the disease leishmaniasis in humans. Among those identified include two that belong to a class of neuropeptides that regulate the critical process of water balance in other blood-feeding insects. In addition, we have mapped neuropeptide storage and release sites in these medically-important insect pests. This information will aid in the development of practical neuropeptide-like substances that can effectively control pest insects in an environmentally friendly fashion.
Technical Abstract: Sandflies (Phlebotominae, Nematocera, Diptera) are responsible for transmission of leishmaniasis and other protozoan-borne diseases in humans, and these insects depend on the regulation of water balance to cope with the sudden and enormous intake of blood over a very short time period. The sandfly inventory of neuropeptides, including those that regulate diuretic processes, is completely unknown. Direct MALDI-TOF/TOF mass spectrometric analysis of dissected ganglia of Phlebotomus papatasi, combined with a data-mining of sandfly genome ‘contigs’, was used to identify native CAPA-peptides, a peptide class associated with the regulation of diuresis in other hematophagous insects. The CAPA-peptides identified in this study include two CAPA-PVKs, differentially processed CAPA-PK, and an additional CAPA precursor peptide. The mass spectrometric analysis of different parts of the neuroendocrine system of the sandfly indicate that it represents the first insect which accumulates CAPA-PVKs exclusively in hormone release sites of abdominal ganglia and CAPA-PK (nearly) exclusively in the corpora cardiaca. Additionally, sandflies feature the smallest abdominal ganglia (approx. 35 um) where CAPA-peptides could be detected so far. The small size of the abdominal ganglia does not appear to affect the development of the median neursecretory system as it obviously does in another comparably small insect species, Nasonia vitripennis, in which no capa-gene expression was found. Rather, immunocytochemical analyses confirm that the general architecture in sandflies appears identical to that of much larger mosquitoes.