| 1. |
- Chen, Wenbo, et al.
(författare)
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The draft genome of whitefly Bemisia tabaci MEAM1, a global crop pest, provides novel insights into virus transmission, host adaptation, and insecticide resistance
- 2016
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Ingår i: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is among the 100 worst invasive species in the world. As one of the most important crop pests and virus vectors, B. tabaci causes substantial crop losses and poses a serious threat to global food security. Results: We report the 615-Mb high-quality genome sequence of B. tabaci Middle East-Asia Minor 1 (MEAM1), the first genome sequence in the Aleyrodidae family, which contains 15,664 protein-coding genes. The B. tabaci genome is highly divergent from other sequenced hemipteran genomes, sharing no detectable synteny. A number of known detoxification gene families, including cytochrome P450s and UDP-glucuronosyltransferases, are significantly expanded in B. tabaci. Other expanded gene families, including cathepsins, large clusters of tandemly duplicated B. tabaci-specific genes, and phosphatidylethanolamine-binding proteins (PEBPs), were found to be associated with virus acquisition and transmission and/or insecticide resistance, likely contributing to the global invasiveness and efficient virus transmission capacity of B. tabaci. The presence of 142 horizontally transferred genes from bacteria or fungi in the B. tabaci genome, including genes encoding hopanoid/sterol synthesis and xenobiotic detoxification enzymes that are not present in other insects, offers novel insights into the unique biological adaptations of this insect such as polyphagy and insecticide resistance. Interestingly, two adjacent bacterial pantothenate biosynthesis genes, panB and panC, have been co-transferred into B. tabaci and fused into a single gene that has acquired introns during its evolution. Conclusions: The B. tabaci genome contains numerous genetic novelties, including expansions in gene families associated with insecticide resistance, detoxification and virus transmission, as well as numerous horizontally transferred genes from bacteria and fungi. We believe these novelties likely have shaped B. tabaci as a highly invasive polyphagous crop pest and efficient vector of plant viruses. The genome serves as a reference for resolving the B. tabaci cryptic species complex, understanding fundamental biological novelties, and providing valuable genetic information to assist the development of novel strategies for controlling whiteflies and the viruses they transmit.
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| 2. |
- Enjin, Anders, et al.
(författare)
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Humidity Sensing in Drosophila
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 26:10, s. 8-1352
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Tidskriftsartikel (refereegranskat)abstract
- Environmental humidity influences the fitness and geographic distribution of all animals [1]. Insects in particular use humidity cues to navigate the environment, and previous work suggests the existence of specific sensory mechanisms to detect favorable humidity ranges [2-5]. Yet, the molecular and cellular basis of humidity sensing (hygrosensation) remains poorly understood. Here we describe genes and neurons necessary for hygrosensation in the vinegar fly Drosophila melanogaster. We find that members of the Drosophila genus display species-specific humidity preferences related to conditions in their native habitats. Using a simple behavioral assay, we find that the ionotropic receptors IR40a, IR93a, and IR25a are all required for humidity preference in D. melanogaster. Yet, whereas IR40a is selectively required for hygrosensory responses, IR93a and IR25a mediate both humidity and temperature preference. Consistent with this, the expression of IR93a and IR25a includes thermosensory neurons of the arista. In contrast, IR40a is excluded from the arista but is expressed (and required) in specialized neurons innervating pore-less sensilla of the sacculus, a unique invagination of the third antennal segment. Indeed, calcium imaging showed that IR40a neurons directly respond to changes in humidity, and IR40a knockdown or IR93a mutation reduced their responses to stimuli. Taken together, our results suggest that the preference for a specific humidity range depends on specialized sacculus neurons, and that the processing of environmental humidity can happen largely in parallel to that of temperature.
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| 3. |
- Mansourian, Suzan, et al.
(författare)
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Fecal-Derived Phenol Induces Egg-Laying Aversion in Drosophila
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822. ; 26:20, s. 2762-2769
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Tidskriftsartikel (refereegranskat)abstract
- Feces is an abundant, rich source of energy, utilized by a myriad of organisms, not least by members of the order Diptera, i.e., flies. How Drosophila melanogaster reacts to fecal matter remains unclear. Here, we examined oviposition behavior toward a range of fecal samples from mammals native to the putative Southeast African homeland of the fly. We show that D. melanogaster display a strong oviposition aversion toward feces from carnivorous mammals but indifference or even attraction toward herbivore dung. We identify a set of four predictor volatiles, which can be used to differentiate fecal from non-fecal matter, as well as separate carnivore from herbivore feces. Of these volatiles, phenol—indicative of carnivore feces—confers egg-laying aversion and is detected by a single class of sensory neurons expressing Or46a. The Or46a-expressing neurons are necessary and sufficient for oviposition site aversion. We further demonstrate that carnivore feces—unlike herbivore dung—contain a high rate of pathogenic bacteria taxa. These harmful bacteria produce phenol from L-tyrosine, an amino acid specifically enriched in high protein diets, such as consumed by carnivores. Finally, we demonstrate that carnivore feces, as well as phenol, is also avoided by a ball-rolling species of dung beetle, suggesting that phenol is a widespread avoidance signal because of its association with pathogenic bacteria.
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| 4. |
- Stensmyr, Marcus C.
(författare)
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Evolutionary Genetics : Smells like a Pseudo-pseudogene
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822. ; 26:24, s. 1294-1296
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Tidskriftsartikel (refereegranskat)abstract
- A new study reports the presence of a chemosensory pseudogene in Drosophila sechellia, which in spite of carrying a premature stop-codon nevertheless encodes a fully functional and full-length protein. Such ‘pseudo-pseudogenes’ might well be a widespread phenomenon.
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