Molecular and Functional Characterization of the Odorant Receptor2 (OR2) in the Tiger Mosquito Aedes albopictus

In mosquitoes, the olfactory system plays a crucial role in many types of behavior, including nectar feeding, host preference selection and oviposition. Aedes albopictus, known also as the tiger mosquito, is an anthropophilic species, which in the last few years, due to its strong ecological plasticity, has spread throughout the world. Although long considered only a secondary vector of viruses, the potential of its vector capacity may constitute a threat to public health. Based on the idea that an improved understanding of the olfactory system of mosquitoes may assist in the development of control methods that interfere with their behavior, we have undertaken a study aimed at characterizing the A. albopictus Odorant Receptors. Here we report the identification, cloning and functional characterization of the AalOR2 ortholog, that represents the first candidate member of the odorant receptor (OR) family of proteins from A. albopictus. AalOR2 is expressed in the larval heads and antennae of adults. Our data indicate that A. albopictus OR2 (AalOR2) shares a high degree of identity with other mosquito OR2 orthologs characterized to date, confirming that OR2 is one of the most conserved mosquito ORs. Our data indicate that AalOR2 is narrowly tuned to indole, and inhibited by (-)-menthone. In agreement with this results, these two compounds elicit two opposite effects on the olfactory-based behavior of A. albopictus larvae, as determined through a larval behavioral assay. In summary, this work has led to the cloning and de-orphaning of the first Odorant Receptor in the tiger mosquito A. albopictus. In future control strategies this receptor may be used as a potential molecular target

Insect Repellents: Modulators of Mosquito Odorant Receptor Activity

Background: DEET, 2-undecanone (2-U), IR3535 and Picaridin are widely used as insect repellents to prevent interactions between humans and many arthropods including mosquitoes. Their molecular action has only recently been studied, yielding seemingly contradictory theories including odorant-dependent inhibitory and odorant-independent excitatory activities on insect olfactory sensory neurons (OSNs) and odorant receptor proteins (ORs). Methodology/Principal Findings: Here we characterize the action of these repellents on two Aedes aegypti ORs, AaOR2 and AaOR8, individually co-expressed with the common co-receptor AaOR7 in Xenopus oocytes; these ORs are respectively activated by the odors indole (AaOR2) and (R)-(2)-1-octen3-ol (AaOR8), odorants used to locate oviposition sites and host animals. In the absence of odorants, DEET activates AaOR2 but not AaOR8, while 2-U activates AaOR8 but not AaOR2; IR3535 and Picaridin do not activate these ORs. In the presence of odors, DEET strongly inhibits AaOR8 but not AaOR2, while 2-U strongly inhibits AaOR2 but not AaOR8; IR3535 and Picaridin strongly inhibit both ORs. Conclusions/Significance: These data demonstrate that repellents can act as olfactory agonists or antagonists, thus modulating OR activity, bringing concordance to conflicting models

Transcriptome profiling of chemosensory appendages in the malaria vector Anopheles gambiae reveals tissue- and sex-specific signatures of odor coding

<p>Abstract</p> <p>Background</p> <p>Chemosensory signal transduction guides the behavior of many insects, including <it>Anopheles gambiae</it>, the major vector for human malaria in sub-Saharan Africa. To better understand the molecular basis of mosquito chemosensation we have used whole transcriptome RNA sequencing (RNA-seq) to compare transcript expression profiles between the two major chemosensory tissues, the antennae and maxillary palps, of adult female and male <it>An. gambiae</it>.</p> <p>Results</p> <p>We compared chemosensory tissue transcriptomes to whole body transcriptomes of each sex to identify chemosensory enhanced genes. In the six data sets analyzed, we detected expression of nearly all known chemosensory genes and found them to be highly enriched in both olfactory tissues of males and females. While the maxillary palps of both sexes demonstrated strict chemosensory gene expression overlap, we observed acute differences in sensory specialization between male and female antennae. The relatively high expression levels of chemosensory genes in the female antennae reveal its role as an organ predominately assigned to chemosensation. Remarkably, the expression of these genes was highly conserved in the male antennae, but at much lower relative levels. Alternatively, consistent with a role in mating, the male antennae displayed significant enhancement of genes involved in audition, while the female enhancement of these genes was observed, but to a lesser degree.</p> <p>Conclusions</p> <p>These findings suggest that the chemoreceptive spectrum, as defined by gene expression profiles, is largely similar in female and male <it>An. gambiae</it>. However, assuming sensory receptor expression levels are correlated with sensitivity in each case, we posit that male and female antennae are perceptive to the same stimuli, but possess inverse receptive prioritizations and sensitivities. Here we have demonstrated the use of RNA-seq to characterize the sensory specializations of an important disease vector and grounded future studies investigating chemosensory processes.</p

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Not AvailableThe present observation was recorded at National Research Centre on Mithun, Jharnapani from May 2010 to September 2012. A total of 15 mithun calves, which died in and around Jharnapani, were attended and detailed post-mortem examination was carried out. Out of these, five calves (33.33 %) aging between 1 and 1.5 years exhibiting the condition of chronic wasting and diarrhoea were found positive for pimply gut condition based on gross and microscopic examination. Post-mortem examination revealed extensive nodule formation on the wall of the rectum; however, the entire lumen did not reveal any of adult parasites. In all the cases, there were congestion in the mucous layer and thickening of the intestinal wall. Histopathological examination revealed chronic enteritis with mononuclear cell infiltration comprising mostly of macrophages, lymphocytes and eosinophils. In the muscularis mucosae, encysted larvae were found along with fibrous tissue proliferation. These lesions gave the intestine a nodular appearance as they thickened the wall and projected from the serosal surface. These extensive numbers of nodules in the intestine might have interfered with peristalsis and intestinal absorption which led to chronic wasting and diarrhoea in the calves.Not Availabl

An investigation on the performance of Di-isopropyl benzyl derivative of Poly (3, 4-propylene dioxythiophene) thin film based electrochromic pixels displays

Electrochromic (EC) smart pixel display was designed and fabricated using a novel monomer di-4-isopropyl benzyl substituted (3, 4-propylene dioxythiophene) (ProDOT-IPBz(2)). The polymer thin film showed absorption between 450 and 650 nm at a fully reduced state. The absorption peak narrowed down slightly towards longer wavelength region (850-900 nm) at the oxidation states. Siju et al has reported the coloration efficiency (CE) of the thin film as similar to 305 cm(2) C-1. The ProDot-IPBZ(2) thin film was used to fabricate EC pixel display of 2 x 2 pixel array on a patterned ITO coated glass. The optical color contrast of the EC pixel display is 40% at 600 nm, with a switching time of about 2 s and 2.5 s respectively. The CE of EC pixel was found to be 555 cm(2) C-1 at 600 nm in the fully doped state. This EC pixel switched for more than 1000 cycles with good color contrast (< 5% T). EC pixel displays showed transmissive, magenta and violet colored states at applied potentials of 1.5, -1.0 and -2.0 V respectively. This EC pixel display is efficient with faster response time and better color contrast