Olle Terenius

Hemolin gene silencing by ds-RNA injected into Cecropia pupae is lethal to next generation embryos

There is increasing evidence of an intimate connection between participants in the innate immune system and in development. Molecules involved in the determination of dorso‐ventral polarity in Drosophila have related counterparts in the signalling pathways for immune gene activation in both insects and mammals. Hemolin from the Giant silkmoth, Hyalophora cecropia, identified as a bacteria‐inducible molecule and a member of the immunoglobulin superfamily, is present as protein and transcripts in oocytes and embryos. We used RNA interference (RNAi) to investigate H. cecropia gene function in vivo and demonstrated that Hemolin is crucial for the normal development of embryos. When RNAi‐females were mated, no larvae emerged from their eggs and when dissected, the eggs revealed malformed embryos. Western blot analysis confirmed the lack of Hemolin gene products. We conclude that Hemolin is necessary for development, since the silencing of Hemolin gene expression leads to embryonic lethality.

Parasite-specific immune response in adult Drosophila melanogaster: a genomic study

Insects of the order Diptera are vectors for parasitic diseases such as malaria, sleeping sickness and leishmania. In the search for genes encoding proteins involved in the antiparasitic response, we have used the protozoan parasite Octosporea muscaedomesticae for oral infections of adult Drosophila melanogaster. To identify parasite‐specific response molecules, other flies were exposed to virus, bacteria or fungi in parallel. Analysis of gene expression patterns after 24 h of microbial challenge, using Affymetrix oligonucleotide microarrays, revealed a high degree of microbe specificity. Many serine proteases, key intermediates in the induction of insect immune responses, were uniquely expressed following infection of the different organisms. Several lysozyme genes were induced in response to Octosporea infection, while in other treatments they were not induced or downregulated. This suggests that lysozymes are important in antiparasitic defence.

Baculovirus and dsRNA induce Hemolin, but no antibacterial activity, in Antheraea pernyi

Hemolin is one of the haemolymph proteins most strongly induced upon bacterial infection in Lepidoptera. When we applied RNA interference (RNAi) to suppress Hemolin expression in the Chinese oak silk moth Antheraea pernyi, we discovered that Hemolin is induced by double‐stranded RNA (dsRNA) per se. As dsRNA is recognized as a virus pattern molecule, we then investigated the effect of a baculovirus (ApNPV) infection. We found that Hemolin is induced and expressed with similar kinetics as upon dsRNA injection. Notably, no Attacin gene expression or antibacterial activity was recorded. When baculovirus and high amounts of dsRNA were coinjected, the viral symptoms appeared earlier with Hemolin dsRNA than with GFP dsRNA. This indicates that silencing of hemolin affected the progress of the viral infection.

Bacterial associations reveal spatial population dynamics in Anopheles gambiae mosquitoes

The intolerable burden of malaria has for too long plagued humanity and the prospect of eradicating malaria is an optimistic, but reachable, target in the 21st century. However, extensive knowledge is needed about the spatial structure of mosquito populations in order to develop effective interventions against malaria transmission. We hypothesized that the microbiota associated with a mosquito reflects acquisition of bacteria in different environments. By analyzing the whole-body bacterial flora of An. gambiae mosquitoes from Burkina Faso by 16 S amplicon sequencing, we found that the different environments gave each mosquito a specific bacterial profile. In addition, the bacterial profiles provided precise and predicting information on the spatial dynamics of the mosquito population as a whole and showed that the mosquitoes formed clear local populations within a meta-population network. We believe that using microbiotas as proxies for population structures will greatly aid improving the performance of vector interventions around the world.

Isolation and identification of culturable bacteria from wild Anopheles culicifacies, a first step in a paratransgenesis approach

BackgroundDue to the effect of midgut bacteria on proliferation of parasites and their potential as paratransgenesis tools, their identification in malaria vector mosquitoes is important. Anopheles culicifacies s.l. is one of the main malaria vectors in Asia; however, its midgut microbiota remains un-studied. This work was primarily designed to isolate potential candidates for use in a paratransgenesis approach, but also to give a picture of the midgut microbiota of wild-caught An. culicifacies larvae and adults from the southeast corner of Iran, which has the highest malaria endemicity in the country.MethodsA total of 68 larvae and 34 adult females (newly eclosed and older) from three different biotopes in Iran were analyzed for their midgut microflora. The mosquitoes had their midgut bacterial contents plated on three different culture media (brain heart agar, nutrient agar and blood agar) yielding 57 bacterial isolates. The 16S rRNA genes of the isolates were sequence analyzed for species designation, which then was confirmed by biochemical analysis.ResultsA total of twelve bacterial genera were identified: Acinetobacter, Aeromonas, Bacillus, Chryseobacterium, Delftia, Exiguobacterium, Kurthia, Microbacterium, Pseudomonas, Staphylococcus, Thorsellia and Variovorax. In older females, only Gram-negative bacteria were found, whereas larvae and newly-eclosed adults also harbored Gram-positive bacteria. The diversity of isolates also varied between sampling sites and mosquito stages, with the largest number of genera found in the Anguri district and in larvae, respectively. Pseudomonas was the most common genus retrieved from all sampling sites, and in both larvae and adults, suggesting a potential transstadial passage of these bacteria. Interestingly, identical 16S sequences of Pseudomonas were found in mosquitoes originating from different habitats at least 45 km apart, which could suggest that these bacteria have been adapted to the mosquitoes.ConclusionsThe study of vector mosquito microbiota has recently gathered increased interest because of the potential influence on vector competence. By adding data from a hitherto uncharacterized malaria mosquito, a better picture of gut flora in vector mosquitoes was obtained. Furthermore, some species of the predominant genus Pseudomonas will be evaluated for the selection of a paratransgenesis candidate.

The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer‐feeding beetles

The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevils ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta‐analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis‐associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients.

Genetic Characterization of a Novel Iflavirus Associated with Vomiting Disease in the Chinese Oak Silkmoth Antheraea pernyi

Larvae of the Chinese oak silkmoth (Antheraea pernyi) are often affected by AVD (A. pernyi vomiting disease), whose causative agent has long been suspected to be a virus. In an unrelated project we discovered a novel positive sense single-stranded RNA virus that could reproduce AVD symptoms upon injection into healthy A. pernyi larvae. The genome of this virus is 10,163 nucleotides long, has a natural poly-A tail, and contains a single, large open reading frame flanked at the 5′ and 3′ ends by untranslated regions containing putative structural elements for replication and translation of the virus genome. The open reading frame is predicted to encode a 3036 amino acid polyprotein with four viral structural proteins (VP1-VP4) located in the N-terminal end and the non-structural proteins, including a helicase, RNA-dependent RNA polymerase and 3C-protease, located in the C-terminal end of the polyprotein. Putative 3C-protease and autolytic cleavage sites were identified for processing the polyprotein into functional units. The genome organization, amino acid sequence and phylogenetic analyses suggest that the virus is a novel species of the genus Iflavirus, with the proposed name of Antheraea pernyi Iflavirus (ApIV).

New and Earlier Records of Ticks (Acari: Ixodidae, Argasidae) from Guinea-Bissau

Abstract Ticks were collected from pastures and domestic and wild vertebrates during the rainy seasons of 1994 and 1996 in Guinea-Bissau. We collected the following species: from pastures Rhipicephalus lunulatus Neumann, R. muhsamae Morel & Vassiliades, R. senegalensis Koch, and R. sulcatus Neumann; from reptiles Amblyomma nuttalli Dönitz and Aponomma flavomaculatum (Lucas); and from mammals Amblyomma paulopunctatum Neumann, Amblyomma splendidum Giebel, Amblyomma variegatum (F.), Hyalomma truncatum Koch, R. muhsamae, R. sanguineus (Latreille), R. senegalensis, and R. sulcatus. New host records are as follows: Amblyomma nuttalli on Senegal flap shelled turtle (Cyclanorbis senegalensis Dumeril & Bibron), Aponomma flavomaculatum on West African dwarf crocodile (Osteolaemus tetraspis Cope), and R. sulcatus on bushbuck (Tragelaphus scriptus Pallas). We reviewed the literature for earlier records of ticks from Guinea-Bissau. The regional distributions of the 21 tick species hitherto recorded in Guinea-Bissau are listed.

Development of an instrument for early detection of dementia in people with Down syndrome

The successful detection of early signs of dementia in people with Down syndrome could form a basis for useful early support and for drug treatment. This report describes the development and preliminary application of an interview and test instrument for the assessment of dementia among people with intellectual disability, as well as a framework for diagnosis that combines the findings of an interview and a test with the diagnostic criteria of ICD-10, DSM-IV and NINCDS-ADRDA. From among the number of tests and interview questions developed, those showing the most significant differences between participants in three groups of differing levels of intellectual disability and estimated dementia were kept. Reported are the assumptions for the items used, descriptions of the process and items used, and the associations of test items with predicting the presence of dementia. The authors conclude that a protocol combining testing and interview has promise and potential for detecting early signs of dementia in this population and could prove feasible for use in practice.

Chemodiversity and biodiversity of fungi associated with the pine weevil Hylobius abietis.

The pine weevil Hylobius abietis is a severe pest of conifer seedlings in reforestation areas. Weevils lay eggs in the root bark or in the soil near roots of recently dead trees and cover the eggs with frass (feces combined with chewed bark), possibly to avoid conspecific egg predation. The aim of the present investigation focused on isolation, identification, and volatile production of fungi from pine-weevil feces and frass. Fungi were isolated from weevil frass and feces separately, followed by identification based on ITS sequencing. Fifty-nine isolates belonging to the genera Penicillium, Ophiostoma, Mucor, Leptographium, Eucasphaeria, Rhizosphaera, Debaryomyces, and Candida were identified. Volatile organic compounds (VOCs) produced by the fungal community and fungal isolates cultured on weevil-frass broth were identified by SPME-GCMS. Major VOCs emitted from the fungal community and pure isolates were species- and strain specific and included isopentylalcohol, styrene, 3-octanone, 6-protoilludene, methyl salicylate, 3-methylanisole, 2-methoxyphenol, and phenol. Some of these are known to influence the orientation of pine weevils when tested among highly attractive newly planted conifer seedlings.