Project description:The midgut of hematophagous insects is the initial site of infection by arthropod-borne viruses (arboviruses) and plays a crucial role in vector competence. To further understand processes that occur in the midgut in response to infection by an arbovirus, DNA microarrays were used to analyze gene expression changes following infection by the alphavirus, Sindbis (MRE16 Malaysian strain). Midgut transcription profiles from mosquitoes fed blood containing 108 pfu/ml of virus were compared with those from mosquitoes ingesting blood meals having no virus. Transcription profiles from both experimental groups were analyzed at 1, 4, and 8 days post feeding. Among the many transcription changes observed by microarray analysis, the most dramatic involved three genes that had twenty-five to forty-fold increases in transcript levels in virus infected mosquitoes at 4 days post infection . These genes were synaptic vesicle protein-2 (SV2), potassium-dependent sodium/calcium exchanger (NCKX), and a homologue of C. elegans Unc-93, a putative component of a two-pore potassium channel. We speculate that these changes represent changes in vesicle transport processes. In addition to these observations, transcript changes were observed in infected mosquitoes that suggested involvement of Toll and JNK immune cascades as a response to viral infection
Project description:The unparalleled success of the insects comprising more than a million species has long stood out to evolutionary biologists. A much overlooked evolutionary innovation of the insects is the serosa, an extraembryonic epithelium that covers yolk and embryo in their eggs. We have shown that this epithelium provides innate immune protection to eggs of the beetle Tribolium castaneum. It remained elusive, however, if this innate immune competence evolved in the Tribolium lineage, or is ancestral to all insects. Here, we expand our studies to the bug Oncopeltus fasciatus that belongs to the basal main group of insects, the Hemimetabola. RNA sequencing reveals an extensive transcriptional response upon infection of the egg with Gram-positive and Gram-negative bacteria. We demonstrate the antimicrobial activity of upregulated peptides using in vitro bacterial growth inhibition assays, and describe two novel families of AMPs called Serosins and Ovicins. By qPCR, we determine that eggs become immune responsive when the serosa develops. Finally, in situ hybridizations show that transcripts of upregulated peptides are located in the serosal cells and not in the underlying embryo. We conclude that the serosa protects the O. fasciatus embryo against pathogens. This first evidence from hemimetabolous insect eggs suggests that immune competence is an ancestral property of the serosa. The evolutionary origin of the serosa with its immune function might have been one of the factors that facilitated the spectacular success of the insects.
Project description:One of the most thoroughly studied insect species, with respect to locomotion behaviour, is the stick insect Carausius morosus. Although detailed information exists on premotor networks controlling walking, surprisingly little is known about neuropeptides, which are certainly involved in motor activity generation and modulation. So far, only few neuropeptides were identified from C. morosus or related stick insects. We performed a transcriptome analysis of the central nervous system to assemble and identify 65 neuropeptide and protein hormone precursors of C. morosus, including five novel putative neuropeptide precursors without clear homology to known neuropeptide precursors of other insects (Carausius neuropeptide-like precursor 1, HanSolin, PK-like1, PK-like2, RFLamide). Using Q Exactive Orbitrap and MALDI-TOF mass spectrometry, 277 peptides including 153 likely bioactive mature neuropeptides were confirmed. Peptidomics yielded a complete coverage for many of the neuropeptide propeptides and confirmed a surprisingly high number of heterozygous sequences. Few neuropeptide precursors commonly occurring in insects, including those of insect kinins and sulfakinins, could neither be found in the transcriptome data nor did peptidomics support their presence. The results of our study represent one of the most comprehensive peptidomic analyses on insects and provide the necessary input for subsequent experiments revealing neuropeptide function in greater detail.
Project description:Determination of miRNA profiles in most prominent mosquitoes will determine the potential targets for mosquito control Some of the most medically important viruses, such as dengue virus, West Nile virus, Zika virus, and yellow fever virus, are transmitted by mosquitoes. These aptly named arboviruses impose a tremendous cost to the health of populations around the world. As a result, much effort has gone into the study of the impact of these viruses in human infections. Comparatively less efforts, however, have been made to study the way these viruses interact with mosquitos themselves. It has long been held that these viruses are introduced into the midgut of mosquitoes upon ingestion of a blood meal before being transmitted within the saliva upon subsequent feeding. This sequence requires that the mosquito be able to defend itself from infection every step along the way-from ingesting bloodmeal to subsequent feeding. The main defense mechanisms employed by the mosquitoes to control viruses is RNA interference (RNAi). Modulation of this facet of the mosquito’s immune system would thereby suggest a practical strategy for vector control. This paper will provide an up to date overview of the mosquito’s immune system along with novel data describing miRNA profiles for Aedes aegypti and Culex quinquefasiatus in Grenada, West Indies.
Project description:Pesticides are widely used to protect growth of crops and prevent the spread of diseases. However, more and more pest insects have developed resistance to chemical pesticides along with the long-term application of the pesticides. It is very important to explore the molecular mechanisms of insecticide resistance not only for reversing the resistance in insects, but also for finding out new function targets of the insecticides. Recently, the next-generation sequence technique has become an effective tool to screen resistance genes and has developed transcriptome profiles of various species. However, a comprehensive database to collect these transcriptome data remains poorly developed. In this study, we constructed a database for insect resistance called IRdb, which contains gene count data from various insect species analyzed by a unified process. In addition to the gene data, IRdb also contains 430 unique resistance proteins (experimentally verified proteins manually extracted from literature). Users can discriminate the resistance proteins by submitting fasta sequence of proteins of interest, which can provide clues to detect resistance proteins. The application of resistance protein part in IRdb indicates the accuracy of prediction of IRdb by extracting CTD features and employing random forest. The database IRdb online web server (http://120.27.24.199:20609/) was provided for users to download the transcriptome and protein data for resistance of insects to insecticides and to predict potential resistance proteins.
Project description:This SuperSeries is composed of the following subset Series: GSE29274: phytoplasma in plants vs. phytoplasma in insects (single hyb expts) GSE30302: phytoplasma in plants vs. phytoplasma in insects (co-hybridizations) Refer to individual Series
Project description:The response of kiwifruit vine (Actinidia chinensis 'Hort16A') canes to feeding by the armoured scale insect Hemiberlesia lataniae was tested by screening RNA extracted from bark against a cDNA library of 17,512 unigenes. Substantial transcriptional changes were noted after 7 days for approximately 30% of the ESTs. Transcripts associated with photosynthesis were down-regulated and those associated with secondary metabolism up-regulated. A large number of transcripts orthologous with defence-related genes were differentially expressed including several orthologous with resistance and pathogenesis. This is the first such analysis of changes to transcript expression in a plant challenged by feeding by insects from the family diaspididae.
Project description:Transcriptome profiling of Anopheles coluzzi mosquitoes collected from two sites in south west Burkina Faso (Vallee du Kou & Tengrela) displaying a deltamethrin resistant phenotype. The resistant insects were compared to two laboratory insecticide susceptible strains.
Project description:microRNAs (miRNAs) have been reported as key regulators in the post-transcriptional process in eukaryotic cells. In insects most of the studies have been reported in holometabolans while only recently two hemimetabolans (Locusta migratoria and Acyrthosiphonpisum) have had their miRNAs identified. Therefore, the study on miRNAs of the evolutionarily basal hemimetabolan Blattella germanica, may provide valuable insights on the structural and functional evolution of miRNAs. Small RNA libraries of the cockroach B. germanica were built from the whole body of the last instar nymph, and the adult ovaries. The high throughput Solexa sequencing resulted in approximately 11 and 8 million reads for the whole-body and ovaries, respectively. Bioinformatic analyses identified 38 known miRNAs as well as 11 known miRNA*s. We also found 411 miRNA candidates conserved in other insects and 1017 candidates specific of B. germanica. The positive correlation between Solexa data and real-time quantitative PCR showed that reads can be used as quantitative method. Novel miRNA candidates were validated by decreasing levels of expression in dicer-1 RNAi knockdown individuals. The comparison of the two libraries indicates that whole-body nymph contain more known miRNAs than ovaries, whereas the adult ovaries are enriched with novel miRNA candidates. Our study has identified many known miRNAs and novel miRNA candidates in the basal hemimetabolan insect B. germanica, and most of the specific sequences were found in ovaries. Deep sequencing data reflect miRNA abundance and Dicer-1 RNAi assay is a reliable method to validate novel miRNAs.