Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Learning-induced gene expression in the heads of two Nasonia species that differ in long-term memory formation
Hoedjes, K.M. ; Smid, H.M. ; Schijlen, E.G.W.M. ; Vet, L.E.M. ; Vugt, J.J.F.A. van - \ 2015
BMC Genomics 16 (2015). - ISSN 1471-2164
natural variation - antisense transcription - protein-synthesis - foraging success - parasitic wasps - drosophila - vitripennis - pathway - consolidation - opportunities
Background Cellular processes underlying memory formation are evolutionary conserved, but natural variation in memory dynamics between animal species or populations is common. The genetic basis of this fascinating phenomenon is poorly understood. Closely related species of Nasonia parasitic wasps differ in long-term memory (LTM) formation: N. vitripennis will form transcription-dependent LTM after a single conditioning trial, whereas the closely-related species N. giraulti will not. Genes that were differentially expressed (DE) after conditioning in N. vitripennis, but not in N. giraulti, were identified as candidate genes that may regulate LTM formation. Results RNA was collected from heads of both species before and immediately, 4 or 24 hours after conditioning, with 3 replicates per time point. It was sequenced strand-specifically, which allows distinguishing sense from antisense transcripts and improves the quality of expression analyses. We determined conditioning-induced DE compared to naïve controls for both species. These expression patterns were then analysed with GO enrichment analyses for each species and time point, which demonstrated an enrichment of signalling-related genes immediately after conditioning in N. vitripennis only. Analyses of known LTM genes and genes with an opposing expression pattern between the two species revealed additional candidate genes for the difference in LTM formation. These include genes from various signalling cascades, including several members of the Ras and PI3 kinase signalling pathways, and glutamate receptors. Interestingly, several other known LTM genes were exclusively differentially expressed in N. giraulti, which may indicate an LTM-inhibitory mechanism. Among the DE transcripts were also antisense transcripts. Furthermore, antisense transcripts aligning to a number of known memory genes were detected, which may have a role in regulating these genes. Conclusion This study is the first to describe and compare expression patterns of both protein-coding and antisense transcripts, at different time points after conditioning, of two closely related animal species that differ in LTM formation. Several candidate genes that may regulate differences in LTM have been identified. This transcriptome analysis is a valuable resource for future in-depth studies to elucidate the role of candidate genes and antisense transcription in natural variation in LTM formation.
Introgression study reveals two quantitative trait loci involved in interspecific variation in memory retention among Nasonia wasp species
Hoedjes, K.M. ; Smid, H.M. ; Vet, L.E.M. ; Werren, J.H. - \ 2014
Heredity 113 (2014). - ISSN 0018-067X - p. 542 - 550.
long-term-memory - natural variation - parasitic wasps - learning rate - drosophila - evolution - consolidation - dynamics - pteromalidae - hymenoptera
Genes involved in the process of memory formation have been studied intensively in model organisms; however, little is known about the mechanisms that are responsible for natural variation in memory dynamics. There is substantial variation in memory retention among closely related species in the parasitic wasp genus Nasonia. After a single olfactory conditioning trial, N. vitripennis consolidates long-term memory that lasts at least 6 days. Memory of the closely related species N. giraulti is present at 24¿h but is lost within 2 days after a single trial. The genetic basis of this interspecific difference in memory retention was studied in a backcrossing experiment in which the phenotype of N. giraulti was selected for in the background of N. vitripennis for up to five generations. A genotyping microarray revealed five regions that were retained in wasps with decreased memory retention. Independent introgressions of individual candidate regions were created using linked molecular markers and tested for memory retention. One region on chromosome 1 (spanning ~5.8¿cM) and another on chromosome 5 (spanning ~25.6¿cM) resulted in decreased memory after 72¿h, without affecting 24-h-memory retention. This phenotype was observed in both heterozygous and homozygous individuals. Transcription factor CCAAT/enhancer-binding protein and a dopamine receptor, both with a known function in memory formation, are within these genomic regions and are candidates for the regulation of memory retention. Concluding, this study demonstrates a powerful approach to study variation in memory retention and provides a basis for future research on its genetic basis.
Unravelling reward value: the effect of host value on memory retention in Nasonia parasitic wasps
Hoedjes, K.M. ; Kralemann, L.E.M. ; Vugt, J.J.F.A. van; Vet, L.E.M. ; Smid, H.M. - \ 2014
Animal Behaviour 96 (2014). - ISSN 0003-3472 - p. 1 - 7.
long-term-memory - sex-ratio - natural variation - pieris-rapae - drosophila - quality - vitripennis - succession - preference - behavior
Learning can be instrumental in acquiring new skills or optimizing behaviour, but it is also costly in terms of energy and when maladaptive associations are formed: the balance between costs and benefits affects memory dynamics. Numerous studies have demonstrated that memory dynamics of animal species depend on the value of the reward during conditioning, even when animals are inexperienced with this reward. How an animal perceives reward value depends on a number of aspects, including the quantity or quality of the reward in terms of energy or fitness for the animal, the internal state of the animal and previous experience. The reliability of the learned association is another aspect, which can be assessed through the frequency of experiences, or through perception of inherent properties of the reward. The reward in oviposition learning of parasitic wasps is a host to parasitize. Different host species can differ in their reward value. This study focused on a specific aspect of reward value, namely host value, i.e. the number and size of emerging offspring, and tested the effect on oviposition learning in parasitic wasps of the genus Nasonia. We conditioned parasitic wasps of the species Nasonia vitripennis and Nasonia giraulti using three different host species as a reward, which differed greatly in their value as a host. However, for both parasitic wasp species, the resulting memory formation was independent of the value of the host. We discuss factors that may be responsible for this observation.
Spectral composition of light sources and insect phototaxis, with an evaluation of existing spectral response models. Journal of Insect Conservation
Grunsven, R.H.A. van; Donners, M. ; Boekee, K. ; Tichelaar, I. ; Geffen, K.G. van; Groenendijk, D. ; Berendse, F. ; Veenendaal, E.M. - \ 2014
Journal of Insect Conservation 18 (2014)2. - ISSN 1366-638X - p. 225 - 231.
artificial-light - compound eyes - color-vision - moths - attraction - pollution - drosophila - diptera - state - trap
Artificial illumination attracts insects, but to what extent light attracts insects, depends on the spectral composition of the light. Response models have been developed to predict the attractiveness of artificial light sources. In this study we compared attraction of insects by existing light sources used for streetlights as well as newly developed environment friendly alternatives, and used this data to test the predictive ability of the existing response models. Light sources differed in overall attractiveness to insects and relative attractiveness was dependent on insect order. The attraction patterns predicted by the two models correlated weakly with the number of insects attracted when the only light source rich in UV, a mercury vapour light, was included in the tested spectra. When the mercury vapour light, which is going to be banned in Europe, was not included in the test no correlation was found between predicted and observed attraction patterns. We conclude that currently existing attraction response models are insufficiently sensitive to evaluate new light sources.
Induction and suppression of tick cell antiviral RNAi responses by tick-borne flaviviruses
Schnettler, E. ; Tykalova, H. ; Watson, M. ; Sharma, M. ; Sterken, M.G. ; Obbard, D.J. ; Lewis, S.H. ; McFarlane, M. ; Bell-Sakyi, L. ; Barry, G. ; Weisheit, S. ; Best, S.M. ; Kuhn, R.J. ; Pijlman, G.P. ; Chase-Topping, M.E. ; Gould, E.A. ; Grubhoffer, L. ; Fazakerley, J.K. ; Kohl, A. - \ 2014
Nucleic acids research 42 (2014)14. - ISSN 0305-1048 - p. 9436 - 9446.
forest-virus replicon - interferon antagonist - arbovirus infection - immunity - replication - drosophila - identification - alphavirus - mosquitos - origin
Arboviruses are transmitted by distantly related arthropod vectors such as mosquitoes (class Insecta) and ticks (class Arachnida). RNA interference (RNAi) is the major antiviral mechanism in arthropods against arboviruses. Unlike in mosquitoes, tick antiviral RNAi is not understood, although this information is important to compare arbovirus/host interactions in different classes of arbovirus vectos. Using an Ixodes scapularis-derived cell line, key Argonaute proteins involved in RNAi and the response against tick-borne Langat virus (Flaviviridae) replication were identified and phylogenetic relationships characterized. Analysis of small RNAs in infected cells showed the production of virus-derived small interfering RNAs (viRNAs), which are key molecules of the antiviral RNAi response. Importantly, viRNAs were longer (22 nucleotides) than those from other arbovirus vectors and mapped at highest frequency to the termini of the viral genome, as opposed to mosquito-borne flaviviruses. Moreover, tick-borne flaviviruses expressed subgenomic flavivirus RNAs that interfere with tick RNAi. Our results characterize the antiviral RNAi response in tick cells including phylogenetic analysis of genes encoding antiviral proteins, and viral interference with this pathway. This shows important differences in antiviral RNAi between the two major classes of arbovirus vectors, and our data broadens our understanding of arthropod antiviral RNAi.
Natural variation in long-term memory formation among Nasonia parasitic wasp species
Hoedjes, K.M. ; Smid, H.M. - \ 2014
Behavioural Processes 105 (2014). - ISSN 0376-6357 - p. 40 - 45.
leptopilina-heterotoma - foraging success - learning rate - drosophila - dynamics - consolidation - vitripennis - bumblebees - dissection - honeybee
Closely related species of parasitic wasps can differ substantially in memory dynamics. In this study we demonstrate differences in the number of conditioning trials required to form long-term memory between the closely related parasitic wasp species Nasonia vitripennis and Nasonia giraulti (Hymenoptera: Pteromalidae). A single conditioning trial, in which a female wasp associates an odour with the reward of finding a host, results in the formation of transcription-dependent long-term memory in N. vitripennis, whereas N. giraulti requires spaced training to do so. Memory formation does not depend on the type of reward: oviposition, which was hypothesized to be a 'larger' reward results in similar memory retention as host feeding in both Nasonia species. There are several genetic and genomic tools available for Nasonia species to identify genetic mechanisms that underlie the observed variation in the number of trials required to form long-term memory.
Sex-linked transcriptional divergence in the hermaphrodite fungus Neurospora tetrasperma
Samils, N. ; Gioti, A. ; Karlsson, M. ; Sun, Y.Y. ; Kasuga, T. ; Bastiaans, E. ; Wang, Z. ; Li, N. ; Townsend, J.P. ; Johannesson, H. - \ 2013
Proceedings of the Royal Society. B: Biological Sciences 280 (2013)1764. - ISSN 0962-8452
biased gene-expression - mating-type chromosomes - false discovery rates - x-chromosome - evolution - crassa - recombination - drosophila - microarrays - selection
In the filamentous ascomycete Neurospora tetrasperma, a large (approx. 7 Mbp) region of suppressed recombination surrounds the mating-type (mat) locus. While the remainder of the genome is largely homoallelic, this region of recombinational suppression, extending over 1500 genes, is associated with sequence divergence. Here, we used microarrays to examine how the molecular phenotype of gene expression level is linked to this divergent region, and thus to the mating type. Culturing N. tetrasperma on agar media that induce sexual/female or vegetative/male tissue, we found 196 genes significantly differentially expressed between mat A and mat a mating types. Our data show that the genes exhibiting mat-linked expression are enriched in the region genetically linked to mating type, and sequence and expression divergence are positively correlated. Our results indicate that the phenotype of mat A strains is optimized for traits promoting sexual/female development and the phenotype of mat a strains for vegetative/male development. This discovery of differentially expressed genes associated with mating type provides a link between genotypic and phenotypic divergence in this taxon and illustrates a fungal analogue to sexual dimorphism found among animals and plants.
Cross-sectoral conflicts for water under climate change: the need to include water quality impacts
Vliet, M.T.H. van; Ludwig, F. ; Kabat, P. - \ 2013
planten - polyploïdie - hybriden - hybridisatie - genomica - evolutie - drosophila - plants - polyploidy - hybrids - hybridization - genomics - evolution
Climate change is expected to increase pressures on water use between different sectors (e.g. agriculture, energy, industry, domestic uses) and ecosystems. While climate change impacts on water availability have been studied widely, less work has been done to assess impacts on water quality. This study proposes a modelling framework to incorporate water quality in analyses of cross-sectoral conflicts for water between human uses and ecosystems under climate change and socio-economic changes. We illustrate this with an example that shows that increasing river temperatures and declines in summer low flow under climate change are likely to increase environmental restrictions on cooling water use, with substantial reductions in power plant capacities in Europe and the US. Hence, conflicts between environmental objectives and electricity supply are expected to increase due to both changes in water availability and water quality (water temperature) under climate change. A new impact modelling framework is proposed, which integrates relations between water availability, water quality and cross-sectoral water uses, including water requirements for ecosystems. This could provide improved understanding of how climate change and socioeconomic developments will affect the ‘water-energy-food-ecosystem nexus’. Index Terms—river flow, water temperature, water quality, climate change, socio-economic developments, human water use, ecosystems
An atlas of over 90.000 conserved noncoding sequences provides insight into crucifer regulatory regions
Haudry, A. ; Platts, A.E. ; Vello, E. ; Hoen, D.R. ; Leclerq, M. ; Williamson, R.J. ; Forczek, E. ; Joly-Lopez, Z. ; Steffen, J.G. ; Hazzouri, K.M. ; Dewar, K. ; Stinchcombe, J.R. ; Schoen, D.J. ; Wang, X. ; Schmutz, J. ; Town, C.D. ; Edger, P.P. ; Pires, J.C. ; Schumaker, K.S. ; Jarvis, D.E. ; Mandakova, T. ; Lysak, M. ; Bergh, E. van den; Schranz, M.E. ; Harrison, P.M. - \ 2013
Nature Genetics 45 (2013). - ISSN 1061-4036 - p. 891 - 898.
arabidopsis-thaliana - human genome - dna elements - ultraconserved elements - brassica-oleracea - gene-expression - evolution - drosophila - size - annotation
Despite the central importance of noncoding DNA to gene regulation and evolution, understanding of the extent of selection on plant noncoding DNA remains limited compared to that of other organisms. Here we report sequencing of genomes from three Brassicaceae species (Leavenworthia alabamica, Sisymbrium irio and Aethionema arabicum) and their joint analysis with six previously sequenced crucifer genomes. Conservation across orthologous bases suggests that at least 17% of the Arabidopsis thaliana genome is under selection, with nearly one-quarter of the sequence under selection lying outside of coding regions. Much of this sequence can be localized to approximately 90,000 conserved noncoding sequences (CNSs) that show evidence of transcriptional and post-transcriptional regulation. Population genomics analyses of two crucifer species, A. thaliana and Capsella grandiflora, confirm that most of the identified CNSs are evolving under medium to strong purifying selection. Overall, these CNSs highlight both similarities and several key differences between the regulatory DNA of plants and other species.
ODoSE: A Webserver for Genome-Wide Calculation of Adaptive Divergence in Prokaryotes
Vos, M. ; Beek, T.A.H. ; Driel, M.A. van; Huynen, M.A. ; Eyre-Walker, A. ; Passel, M.W.J. van - \ 2013
PLoS ONE 8 (2013)5. - ISSN 1932-6203
positive selection - evolution - recombination - drosophila - campylobacter
Quantifying patterns of adaptive divergence between taxa is a major goal in the comparative and evolutionary study of prokaryote genomes. When applied appropriately, the McDonald-Kreitman (MK) test is a powerful test of selection based on the relative frequency of non-synonymous and synonymous substitutions between species compared to non-synonymous and synonymous polymorphisms within species. The webserver ODoSE (Ortholog Direction of Selection Engine) allows the calculation of a novel extension of the MK test, the Direction of Selection (DoS) statistic, as well as the calculation of a weighted-average Neutrality Index (NI) statistic for the entire core genome, allowing for systematic analysis of the evolutionary forces shaping core genome divergence in prokaryotes. ODoSE is hosted in a Galaxy environment, which makes it easy to use and amenable to customization and is freely available at www.odose.nl
High-throughput olfactory conditioning and memory retention test show variation in Nasonia parasitic wasps.
Hoedjes, K.M. ; Steidle, J.L.M. ; Werren, J.H. ; Vet, L.E.M. ; Smid, H.M. - \ 2012
Genes, Brain and Behavior 11 (2012)7. - ISSN 1601-1848 - p. 879 - 887.
long-term-memory - cotesia-glomerata - natural variation - learning rate - vitripennis - hymenoptera - drosophila - pteromalidae - dissection - preference
Most of our knowledge on learning and memory formation results from extensive studies on a small number of animal species. Although features and cellular pathways of learning and memory are highly similar in this diverse group of species, there are also subtle differences. Closely related species of parasitic wasps display substantial variation in memory dynamics and can be instrumental to understanding both the adaptive benefit of and mechanisms underlying this variation. Parasitic wasps of the genus Nasonia offer excellent opportunities for multidisciplinary research on this topic. Genetic and genomic resources available for Nasonia are unrivaled among parasitic wasps, providing tools for genetic dissection of mechanisms that cause differences in learning. This study presents a robust, high-throughput method for olfactory conditioning of Nasonia using a host encounter as reward. A T-maze olfactometer facilitates high-throughput memory retention testing and employs standardized odors of equal detectability, as quantified by electroantennogram recordings. Using this setup, differences in memory retention between Nasonia species were shown. In both Nasonia vitripennis and Nasonia longicornis, memory was observed up to at least 5 days after a single conditioning trial, whereas Nasonia giraulti lost its memory after 2 days. This difference in learning may be an adaptation to species-specific differences in ecological factors, for example, host preference. The high-throughput methods for conditioning and memory retention testing are essential tools to study both ultimate and proximate factors that cause variation in learning and memory formation in Nasonia and other parasitic wasp species.
Reward Value Determines Memory Consolidation in Parasitic Wasps
Kruidhof, H.M. ; Pashalidou, F.G. ; Fatouros, N.E. ; Figueroa, I.A. ; Vet, L.E.M. ; Smid, H.M. ; Huigens, M.E. - \ 2012
PLoS ONE 7 (2012)8. - ISSN 1932-6203
long-term-memory - trichogramma wasps - cotesia-glomerata - protein-synthesis - natural variation - apis-mellifera - learning rate - c-rubecula - drosophila - quality
Animals can store learned information in their brains through a series of distinct memory forms. Short-lasting memory forms can be followed by longer-lasting, consolidated memory forms. However, the factors determining variation in memory consolidation encountered in nature have thus far not been fully elucidated. Here, we show that two parasitic wasp species belonging to different families, Cotesia glomerata (Hymenoptera: Braconidae) and Trichogramma evanescens (Hymenoptera; Trichogrammatidae), similarly adjust the memory form they consolidate to a fitness-determining reward: egg-laying into a host-insect that serves as food for their offspring. Protein synthesis-dependent long-term memory (LTM) was consolidated after single-trial conditioning with a high-value host. However, single-trial conditioning with a low-value host induced consolidation of a shorter-lasting memory form. For Cotesia glomerata, we subsequently identified this shorter-lasting memory form as anesthesia-resistant memory (ARM) because it was not sensitive to protein synthesis inhibitors or anesthesia. Associative conditioning using a single reward of different value thus induced a physiologically different mechanism of memory formation in this species. We conclude that the memory form that is consolidated does not only change in response to relatively large differences in conditioning, such as the number and type of conditioning trials, but is also sensitive to more subtle differences, such as reward value. Reward-dependent consolidation of exclusive ARM or LTM provides excellent opportunities for within-species comparison of mechanisms underlying memory consolidation.
Europese invasie door de fruitvlieg Drosophila suzukii (poster)
Helsen, H.H.M. - \ 2012
drosophila - plantenplagen - insectenplagen - fruitteelt - plagenbestrijding - bedrijfshygiëne - landbouwkundig onderzoek - drosophila suzukii - plant pests - insect pests - fruit growing - pest control - industrial hygiene - agricultural research
Powerpointpresentatie over een nieuwe plaag op fruit in Nederland door de fruitvlieg Drosophila suzukii.
Mical links semaphorins to F-actin disassembly
Hung, R.J. ; Yazdani, U. ; Yoon, J. ; Wu, H. ; Yang, T. ; Gupta, N. ; Huang, Z. ; Berkel, W.J.H. van; Terman, J.R. - \ 2010
Nature 463 (2010). - ISSN 0028-0836 - p. 823 - 827.
growth cones - drosophila - collapse - molecule - protein - 3a - microtubules - organization - cytoskeleton - morphology
How instructive cues present on the cell surface have their precise effects on the actin cytoskeleton is poorly understood. Semaphorins are one of the largest families of these instructive cues and are widely studied for their effects on cell movement, navigation, angiogenesis, immunology and cancer(1). Semaphorins/collapsins were characterized in part on the basis of their ability to drastically alter actin cytoskeletal dynamics in neuronal processes(2), but despite considerable progress in the identification of semaphorin receptors and their signalling pathways(3), the molecules linking them to the precise control of cytoskeletal elements remain unknown. Recently, highly unusual proteins of the Mical family of enzymes have been found to associate with the cytoplasmic portion of plexins, which are large cell-surface semaphorin receptors, and to mediate axon guidance, synaptogenesis, dendritic pruning and other cell morphological changes(4-7). Mical enzymes perform reduction-oxidation (redox) enzymatic reactions(4,5,8-10) and also contain domains found in proteins that regulate cell morphology(4,11). However, nothing is known of the role of Mical or its redox activity in mediating morphological changes. Here we report that Mical directly links semaphorins and their plexin receptors to the precise control of actin filament (F-actin) dynamics. We found that Mical is both necessary and sufficient for semaphorin-plexin-mediated F-actin reorganization in vivo. Likewise, we purified Mical protein and found that it directly binds F-actin and disassembles both individual and bundled actin filaments. We also found that Mical utilizes its redox activity to alter F-actin dynamics in vivo and in vitro, indicating a previously unknown role for specific redox signalling events in actin cytoskeletal regulation. Mical therefore is a novel F-actin-disassembly factor that provides a molecular conduit through which actin reorganization-a hallmark of cell morphological changes including axon navigation-can be precisely achieved spatiotemporally in response to semaphorins.
Hitch-hiking parasitic wasp learns to exploit butterfly antiaphrodisiac
Huigens, M.E. ; Pashalidou, F.G. ; Qian, M.H. ; Bukovinszky, T. ; Smid, H.M. ; Loon, J.J.A. van; Dicke, M. ; Fatouros, N.E. - \ 2009
Proceedings of the National Academy of Sciences of the United States of America 106 (2009)3. - ISSN 0027-8424 - p. 820 - 825.
long-term-memory - sex-pheromone - trichogramma - drosophila - behavior - consolidation - hymenoptera - dissection - plasticity - selection
Many insects possess a sexual communication system that is vulnerable to chemical espionage by parasitic wasps. We recently discovered that a hitch-hiking (H) egg parasitoid exploits the antiaphrodisiac pheromone benzyl cyanide (BC) of the Large Cabbage White butterfly Pieris brassicae. This pheromone is passed from male butterflies to females during mating to render them less attractive to conspecific males. When the tiny parasitic wasp Trichogramma brassicae detects the antiaphrodisiac, it rides on a mated female butterfly to a host plant and then parasitizes her freshly laid eggs. The present study demonstrates that a closely related generalist wasp, Trichogramma evanescens, exploits BC in a similar way, but only after learning. Interestingly, the wasp learns to associate an H response to the odors of a mated female P. brassicae butterfly with reinforcement by parasitizing freshly laid butterfly eggs. Behavioral assays, before which we specifically inhibited long-term memory (LTM) formation with a translation inhibitor, reveal that the wasp has formed protein synthesis-dependent LTM at 24 h after learning. To our knowledge, the combination of associatively learning to exploit the sexual communication system of a host and the formation of protein synthesis-dependent LTM after a single learning event has not been documented before. We expect it to be widespread in nature, because it is highly adaptive in many species of egg parasitoids. Our finding of the exploitation of an antiaphrodisiac by multiple species of parasitic wasps suggests its use by Pieris butterflies to be under strong selective pressure
Development of a wingless morph in the ladybird beetle, Adalia bipunctata
Lommen, S.T.E. ; Saenko, S.V. ; Tomoyasu, Y. - \ 2009
Evolution & Development 11 (2009)3. - ISSN 1520-541X - p. 278 - 289.
aphid acyrthosiphon-pisum - tribolium-castaneum - coleoptera - evolution - wings - dimorphism - drosophila - flightlessness - polymorphism - polyphenism
Many taxa of winged insects have independently lost the ability to fly and often possess reduced wings. Species exhibiting natural variation in wing morphology provide opportunities to investigate the genetics and developmental processes underlying the evolution of alternative wing morphs. Although many wing dimorphic species of beetles are known, the underlying mechanisms of variation are not well understood in this insect order. Here, we examine wing development of wild type and natural wingless morphs of the two-spot ladybird beetle, Adalia bipunctata. We show that both pairs of wings are distally truncated in the wingless adults. A laboratory population of the wingless morph displays heritable variation in the degree of wing truncation, reflecting reduced growth of the larval wing discs. The coexistence of variable wingless morphs supports the idea that typical monomorphic wingless insects may be the result of a gradual evolution of wing loss. Gene expression patterns in wing discs suggest that the conserved gene network controlling wing development in wild-type Adalia is disrupted in the dorsoventral patterning pathway in the wingless morphs. Previous research on several species of ant has revealed that the anteroposterior wing patterning pathway is disrupted in wingless workers. Future investigations should confirm whether interruptions in both taxa are limited to the patterning pathways found thus far, or whether there are also shared interruption points. Nevertheless, our results highlight that diverse mechanisms of development are likely to underlie the evolution of wingless insects.
The NS3 protein of rice hoja blanca virus complements the RNAi suppressor function of HIV-1 Tat
Schnettler, E. ; Vries, W. de; Hemmes, J.C. ; Haasnoot, J. ; Kormelink, R.J.M. ; Goldbach, R.W. ; Berkhout, B. - \ 2009
Embo Reports 10 (2009). - ISSN 1469-221X - p. 258 - 263.
small interfering rnas - double-stranded-rna - hepatitis-c virus - mammalian-cells - alpha/beta-interferon - antiviral immunity - defense responses - core protein - plant - drosophila
The question of whether RNA interference (RNAi) acts as an antiviral mechanism in mammalian cells remains controversial. The antiviral interferon (IFN) response cannot easily be distinguished from a possible antiviral RNAi pathway owing to the involvement of double-stranded RNA (dsRNA) as a common inducer molecule. The non-structural protein 3 (NS3) protein of rice hoja blanca virus (RHBV) is an RNA silencing suppressor (RSS) that exclusively binds to small dsRNA molecules. Here, we show that this plant viral RSS lacks IFN antagonistic activity, yet it is able to substitute the RSS function of the Tat protein of human immunodeficiency virus type 1. An NS3 mutant that is deficient in RNA binding and its associated RSS activity is inactive in this complementation assay. This cross-kingdom suppression of RNAi in mammalian cells by a plant viral RSS indicates the significance of the antiviral RNAi response in mammalian cells and the usefulness of well-defined RSS proteins
Biofluiddynamic scaling of flapping, spinning and translating fins and wings
Lentink, D. ; Dickinson, M.H. - \ 2009
Journal of Experimental Biology 212 (2009)16. - ISSN 0022-0949 - p. 2691 - 2704.
low reynolds-numbers - unsteady aerodynamic performance - insect flight - revolving wings - hovering flight - lift - animals - vortex - drosophila - mechanism
Organisms that swim or fly with fins or wings physically interact with the surrounding water and air. The interactions are governed by the morphology and kinematics of the locomotory system that form boundary conditions to the Navier–Stokes (NS) equations. These equations represent Newton's law of motion for the fluid surrounding the organism. Several dimensionless numbers, such as the Reynolds number and Strouhal number, measure the influence of morphology and kinematics on the fluid dynamics of swimming and flight. There exists, however, no coherent theoretical framework that shows how such dimensionless numbers of organisms are linked to the NS equation. Here we present an integrated approach to scale the biological fluid dynamics of a wing that flaps, spins or translates. Both the morphology and kinematics of the locomotory system are coupled to the NS equation through which we find dimensionless numbers that represent rotational accelerations in the flow due to wing kinematics and morphology. The three corresponding dimensionless numbers are (1) the angular acceleration number, (2) the centripetal acceleration number, and (3) the Rossby number, which measures Coriolis acceleration. These dimensionless numbers consist of length scale ratios, which facilitate their geometric interpretation. This approach gives fundamental insight into the physical mechanisms that explain the differences in performance among flapping, spinning and translating wings. Although we derived this new framework for the special case of a model fly wing, the method is general enough to make it applicable to other organisms that fly or swim using wings or fins
Sperm quantity and size variation in un-irradiated and irradiated males of the malaria mosquito Anopheles arabiensis Patton
Helinski, M. ; Knols, B.G.J. - \ 2009
Acta Tropica 109 (2009)1. - ISSN 0001-706X - p. 64 - 69.
mediterranean fruit-flies - fly diptera-tephritidae - gambiae mosquitos - mating competitiveness - reproductive-system - long sperm - age - drosophila - insects - storage
Anopheles mosquitoes are important candidates for genetic control strategies. However, little is known about sperm quality and quantity as determinants of male reproductive success. In this study, sperm quantity and length variation were assessed in testes of un-irradiated and irradiated Anopheles arabiensis. Male reproductive organs were dissected for sperm and an estimate of the total number of spermatozoa was made. Sperm lengths were measured using imaging software. The effects of irradiation were evaluated for males exposed in the pupal or adult stage to a full (120 Gy) or partially sterilising dose (70 Gy). Sperm length variation in the laboratory strain was compared to the distribution observed in wild males. We also determined the size distribution of sperm lengths in spermathecae of inseminated females compared to those observed in male testes. Sperm quantity increased with age, and 12-day-old males had significantly more sperm in their testes (8214 ± 467) than males aged 3 days (5022 ± 375). Mosquitoes irradiated in the pupal stage had significantly fewer sperm (2982 ± 125) than un-irradiated males (4950 ± 848) although for adult stage irradiation similar amounts of sperm were observed compared to un-irradiated males. Sperm length variation was detected with sperm lengths ranging between
Morphological transitions and the genetic basis of the evolution of extraembryonic tissues in flies
Rafiqi, A.M. - \ 2008
Wageningen University. Promotor(en): Ton Bisseling, co-promotor(en): U. Schmidt-Ott. - [S.l.] : S.n. - ISBN 9789085852100 - 118
drosophila - moleculaire genetica - evolutie - genexpressie - episyrphus balteatus - genen - serosa - ontogenie - molecular genetics - evolution - gene expression - genes - ontogeny
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