Gene and miR Expression in the Yellow Fever Mosquito Aedes aegypti

When animals are exposed to new conditions they need to tune the expression of hundreds of genes in specific tissues and at a specific time requires the interplay of multiple processes. Females are required to locate suitable oviposition sites after acquiring a blood meal. Mosquitoes possess a variety of genes responsible for chemosensation, with four families standing out: Olfaction Receptors (ORs), Ionotropic Receptors (IRs), Odorant Binding Proteins (OBPs), and Gustatory Receptors (GRs). To investigate the genes that may be involved in host seeking behavior, mRNA was sequenced from samples of A. aegypti male and female tissues using RNA-seq analysis. Simultaneously, small RNA was isolated and sequenced. MicroRNAs (miRs) can regulate genes post-transcriptionally and are thought to be important for olfaction gene regulation in the antenna of mosquitoes. Or46 and Or99 are expressed only in unfed females, while Or49 is only expressed post blood meal. A total of 14 IRs, 6 ORs and 6 OBPs are up regulated post feeding, while 8 IRs, 4 ORs and 11 OBPs are down regulated post feeding. A total of 16 new miRs were discovered in the antenna of females. miR-34, miR-79, miR-929, and miR-965 are uniquely expressed in the female antenna; while miR-92b is uniquely expressed in male antenna, while miR-279 is up regulated in the antenna of both males and females. The expression of the miR-275, which is associated with blood meal digestion, increases 3h after blood feeding in the head and thorax and miR-305 displays a similar expression pattern. This is the first study to find miRs that are uniquely expressed in the antenna of mosquitoes. Although there are differences in the expression of olfaction genes in the antenna of 12h old females and 4-day-old females, no changes are observed after blood feeding and similar observations were noted for miRs. Changes may occur only in a specific subset of sensory neurons in the antenna of females and for this reason could not be detected. Olfaction transcripts with long 3’UTR may compete for miRs binding and gene regulation in the antenna of mosquitoes without dramatic changes at the transcript level

Diuretic hormones of Tribolium castaneum (Herbst)(Coleoptera: tenebrionidae)

Master of ScienceDepartment of EntomologyYoonseong ParkNeuropeptides are diffusible signal molecules mediating vital physiological processes. We have been interested in a group of neuropeptides and their receptors involved in osmoregulatory neuroendocrine system which has been suggested as a possible target for development of new biopesticides. Since the genome sequence of the T. castaneum has recently been completed, we were able to identify the respective genes encoding three peptide hormones from T. castaneum that were characterized for their diuretic activities in other insects: one calcitonin-like (CT-like DH31) and two corticotropin releasing factor-like (CRF-like DH37 and DH47, the numbers indicates the number of amino acid residues). This peptide is expressed at all developmental stages and in the central nervous system (CNS), Malpighian tubules (MT) and gut. The synthetic peptide TricaDH31 also has been show to be biologically active, inducing significant excretions in adults beetles. When Tcdh31 was silenced using RNAi, adults had deformed wings and abnormal body shape. Mortality in adults was high, the number of eggs laid was reduced as well as the hatchability of the eggs. The two biologically active CRF-like peptides in T. castaneum, are encoded by one gene which undergoes alternative splicing. When Tcdh47 was knocked down, high mortality occurred as well as low oviposition and egg hatchability. Similar effects were observed with silencing of both CRF-like genes. However, RNAi of Tcdh37 transcripts had similar, but less severe effects. Adults also had deformed wings when both CRF-like genes were silenced, but not when just one of them was knocked down. These results indicate that CRF-like genes could have additional biological functions to their roles in dieresis. We tested the in vivo activity of these peptides. TenmoDH47 induced high excretions in adults, whereas TenmoDH37 induces smaller excretions. We identified the respective genes encoding two putative receptors for TricaDH31 as Glean_13321 and Glean_02694 (Trica-ctr1 and Trica-ctr2, respectively) and two receptors for CRF-like peptide as Glean_12799 and Glean_07104 (Trica-crfr1 and Trica-crfr2, respectively). The CT-like receptors are expressed at all developmental stages, in the CNS and MT. RNAi of the receptors revealed that only Trica-ctr2 silencing caused significant mortality and reduction in the number of eggs laid. The CRF-like receptors are expressed at all developmental stages. Adults also had deformed wings and laid fewer eggs after RNAi of Trica-crfr1. RNAi of Trica-crf2 also caused significant mortality. These peptides and receptors seem to fine tune the beetle physiology and may have functions not yet known

Olfactory gene expression of male Anopheles coluzzii and Anopheles quadriannulatus

Characterization of the expression of olfactory genes in the antennae of male Anopheles coluzzii and Anopheles quadriannulatus to compare to female expression as part of an effort to identify candidate genes for vertebrate host preference

Olfactory gene expression of male Anopheles coluzzii and Anopheles quadriannulatus

Characterization of the expression of olfactory genes in the antennae of male Anopheles coluzzii and Anopheles quadriannulatus to compare to female expression as part of an effort to identify candidate genes for vertebrate host preference

Anopheles coluzzii and Anopheles quadriannulatus olfactory gene expression

RNAseq data from Anopheles coluzzii and Anopheles quadriannulatus antennae and maxillary palps

Species-specific chemosensory gene expression in the olfactory organs of the malaria vector Anopheles gambiae

Background: The malaria mosquito Anopheles gambiae has a high preference for human hosts, a characteristic that contributes greatly to its capacity for transmitting human malaria. A sibling species, An. quadriannulatus, has a quite different host preference and feeds mostly on bovids. For this reason it does not contribute to human malaria transmission. Host seeking in mosquitoes is modulated by the olfactory system, which is primarily housed in the antennae and maxillary palps. Therefore, the detection of differing host odors by sibling species may be reflected in the expression level of the olfactory genes involved. Accordingly, we compared the transcriptomes of the antennae and maxillary palps of An. gambiae and An. quadriannulatus. Results: We identified seven relatively abundant olfactory receptors, nine ionotropic receptors and three odorant binding proteins that are substantially up-regulated in An. gambiae antennae. Interestingly, we find that the maxillary palps of An. gambiae contain a species-specific olfactory receptor, Or52, and five An. gambiae-specific gustatory receptors (AgGr48-52) that are relatively abundant. These five gustatory receptors are also expressed in An. gambiae antennae, although at lower level, indicating a likely role in olfaction, rather than gustation. We also document an approximately three-fold higher overall expression of olfaction genes in the maxillary palps of An. quadriannulatus, indicating an important role of this organ in the olfaction system of this species. Finally, the expression of the CO2 receptor genes is five to six-fold higher in the zoophilic An. quadriannulatus, implying a much higher sensitivity for detecting CO2. Conclusions: These results identify potential human host preference genes in the malaria vector An. gambiae. Interestingly, species-specific expression of several gustatory receptors in the olfactory organs indicate a role in olfaction rather than gustation. Additionally, a more expansive role for maxillary palps in olfaction is implicated than previously thought, albeit more so in the zoophilic An. quadriannulatus.(The Retraction Note to this article has been published in BMC Genomics 2015 16:572

Anopheles coluzzii and Anopheles quadriannulatus olfactory gene expression

RNAseq data from Anopheles coluzzii and Anopheles quadriannulatus antennae and maxillary palps

Chemosensory gene expression in olfactory organs of the anthropophilic Anopheles coluzzii and zoophilic Anopheles quadriannulatus

Background: Anopheles (An.) coluzzii, one of Africa's primary malaria vectors, is highly anthropophilic. This human host preference contributes greatly to its ability to transmit malaria. In contrast, the closely related An. quadriannulatus prefers to feed on bovids and is not thought to contribute to malaria transmission. The diverged preference for host odor profiles between these sibling species is likely reflected in chemosensory gene expression levels in the olfactory organs. Therefore, we compared the transcriptomes of the antennae and maxillary palps between An. coluzzii and An. quadriannulatus, focusing on the major chemosensory gene families. Results: While chemosensory gene expression is strongly correlated between the two species, various chemosensory genes show significantly enhanced expression in one of the species. In the antennae of An. coluzzii the expression of six olfactory receptors (Ors) and seven ionotropic receptors (Irs) is considerably enhanced, whereas 11 Ors and 3 Irs are upregulated in An. quadriannulatus. In the maxillary palps, leaving aside Irs with very low level of expression, one Ir is strongly enhanced in each species. In addition, we find divergence in odorant binding protein (Obp) gene expression, with several highly expressed Obps being enhanced in the antennae and palps of An. coluzzii. Finally, the expression of several gustatory receptors (Grs) in the palps appears to be species-specific, including a homolog of a sugar-sensing Drosophila Gr. Conclusions: A considerable number of Ors and Irs are differentially expressed between these two closely related species with diverging host preference. These chemosensory genes could play a role in the human host preference of the malaria vector An. coluzzii. Additionally, divergence in Obp expression between the two species suggests a possible role of these odor carrier proteins in determining host preference. Finally, divergence in chemosensory expression in the palps may point towards a possible role for the maxillary palps in host differentiation.</p