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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Maternal provision of non-sex-specific transformer messenger RNA in sex determination of the wasp Asobara tabida
Geuverink, Elzemiek ; Verhulst, E.C. ; Leussen, M. van; Zande, L. ; Beukeboom, Leo W. - \ 2018
Insect Molecular Biology 27 (2018)1. - ISSN 0962-1075 - p. 99 - 109.
Doublesex - Hymenoptera - Maternal provision - Sex determination - Transformer - Transformer-2
In many insect species maternal provision of sex-specifically spliced messenger RNA (mRNA) of sex determination genes is an essential component of the sex determination mechanism. In haplodiploid Hymenoptera, maternal provision in combination with genomic imprinting has been shown for the parasitoid Nasonia vitripennis, known as maternal effect genomic imprinting sex determination (MEGISD). Here, we characterize the sex determination cascade of Asobara tabida, another hymenopteran parasitoid. We show the presence of the conserved sex determination genes doublesex (dsx), transformer (tra) and transformer-2 (tra2) orthologues in As. tabida. Of these, At-dsx and At-tra are sex-specifically spliced, indicating a conserved function in sex determination. At-tra and At-tra2 mRNA is maternally provided to embryos but, in contrast to most studied insects, As. tabida females transmit a non-sex-specific splice form of At-tra mRNA to the eggs. In this respect, As. tabida sex determination differs from the MEGISD mechanism. How the paternal genome can induce female development in the absence of maternal provision of sex-specifically spliced mRNA remains an open question. Our study reports a hitherto unknown variant of maternal effect sex determination and accentuates the diversity of insect sex determination mechanisms.
Maternal provision of transformer-2 is required for female development and embryo viability in the wasp Nasonia vitripennis
Geuverink, Elzemiek ; Rensink, Anna H. ; Rondeel, Inge ; Beukeboom, Leo W. ; Zande, Louis van de; Verhulst, Eveline C. - \ 2017
Insect Biochemistry and Molecular Biology 90 (2017). - ISSN 0965-1748 - p. 23 - 33.
Diploid males - Nasonia vitripennis - RNA interference - Sex determination - Transformer - Transformer-2

In insect sex determination a primary signal starts the genetic sex determination cascade that, in most insect orders, is subsequently transduced down the cascade by a transformer (tra) ortholog. Only a female-specifically spliced tra mRNA yields a functional TRA-protein that forms a complex with TRA2, encoded by a transformer-2 (tra2) ortholog, to act as a sex specific splicing regulator of the downstream transcription factors doublesex (dsx) and fruitless (fru). Here, we identify the tra2 ortholog of the haplodiploid parasitoid wasp N. vitripennis (Nv-tra2) and confirm its function in N. vitripennis sex determination. Knock down of Nv-tra2 by parental RNA interference (pRNAi) results in complete sex reversal of diploid offspring from female to male, indicating the requirement of Nv-tra2 for female sex determination. As Nv-tra2 pRNAi leads to frequent lethality in early developmental stages, maternal provision of Nv-tra2 transcripts is apparently also required for another, non-sex determining function during embryogenesis. In addition, lethality following Nv-tra2 pRNAi appears more pronounced in diploid than in haploid offspring. This diploid lethal effect was also observed following Nv-tra pRNAi, which served as a positive control in our experiments. As diploid embryos from fertilized eggs have a paternal chromosome set in addition to the maternal one, this suggests that either the presence of this paternal chromosome set or the dosage effect resulting from the diploid state is incompatible with the induced male development in N. vitripennis caused by either Nv-tra2 or Nv-tra pRNAi. The role of Nv-tra2 in activating the female sex determination pathway yields more insight into the sex determination mechanism of Nasonia.

Evidence from pyrosequencing indicates that natural variation in animal personality is associated with DRD4 DNA methylation
Verhulst, Eveline C. ; Mateman, A.C. ; Zwier, Mathijs V. ; Caro, Samuel P. ; Verhoeven, Koen J.F. ; Oers, Kees Van - \ 2016
Molecular Ecology 25 (2016)8. - ISSN 0962-1083 - p. 1801 - 1811.
behaviour - birds - DNA methylation - epigenetics - personality

Personality traits are heritable and respond to natural selection, but are at the same time influenced by the ontogenetic environment. Epigenetic effects, such as DNA methylation, have been proposed as a key mechanism to control personality variation. However, to date little is known about the contribution of epigenetic effects to natural variation in behaviour. Here, we show that great tit (Parus major) lines artificially selected for divergent exploratory behaviour for four generations differ in their DNA methylation levels at the dopamine receptor D4 (DRD4) gene. This D4 receptor is statistically associated with personality traits in both humans and nonhuman animals, including the great tit. Previous work in this songbird failed to detect functional genetic polymorphisms within DRD4 that could account for the gene-trait association. However, our observation supports the idea that DRD4 is functionally involved in exploratory behaviour but that its effects are mediated by DNA methylation. While the exact mechanism underlying the transgenerational consistency of DRD4 methylation remains to be elucidated, this study shows that epigenetic mechanisms are involved in shaping natural variation in personality traits. We outline how this first finding provides a basis for investigating the epigenetic contribution to personality traits in natural systems and its subsequent role for understanding the ecology and evolution of behavioural consistency.

Data from: Evidence from pyrosequencing indicates that natural variation in animal personality is associated with DRD4 DNA methylation
Verhulst, E.C. ; Mateman, A.C. ; Zwier, Mathijs V. ; Caro, Samuel P. ; Verhoeven, K.J.F. ; Oers, Kees van - \ 2015
epigenetics - behaviour - personality - DNA methylation - birds
Contain all the individual methylation levels per CpG position for assays A-D. Each tab ($data_$assay_$tissuetype) contains the results from one pyrosequence run and one type of tissue (blood or brain). The columns indicate: SampleID: bird sample Note: EEB score, F is Fast exploring, S is Slow exploring Pos. 1 Meth%: Methylation percentage for CpG position 1 in assayB Pos. 2 Meth%: Methylation percentage for CpG position 2 in assayB Etc. Cell colours indicate quality scores In green: highly reliable methylation scores In yellow: reliable methylation scores In pink: unreliable methylation scores (not used in downstream analyses) SampleID with *_replicate indicates that the DNA sample with this number was used in duplo on this plate for within assay analysis.
Double nexus—Doublesex is the connecting element in sex determination
Verhulst, E.C. ; Zande, L. van de - \ 2015
Briefings in Functional Genomics 14 (2015)6. - ISSN 2041-2649 - p. 396 - 406.
In recent years, our knowledge of the conserved master-switch gene doublesex (dsx) and its function in regulating the development of dimorphic traits in insects has deepened considerably. Here, a comprehensive overview is given on the properties of the male- and female-specific dsx transcripts yielding DSXF and DSXM proteins in Drosophila melanogaster, and the many downstream targets that they regulate. As insects have cell-autonomous sex determination, it was assumed that dsx would be expressed in every somatic cell, but recent research showed that dsx is expressed only when a cell is required to show its sexual identity through function or morphology. This spatiotemporal regulation of dsx expression has not only been established in D. melanogaster but in all insect species studied. Gradually, it has been appreciated that dsx could no longer be viewed as the master-switch gene orchestrating sexual development and behaviour in each cell, but instead should be viewed as the interpreter for the sexual identity of the cell, expressing this identity only on request, making dsx the central nexus of insect sex determination
Great tit de novo genome assembly and annotation
Laine, V. ; Oers, K. van; Madsen, O. ; Megens, H.J.W.C. ; Verhulst, E.C. ; Verhoeven, M.T.W. ; Visser, M.E. ; Groenen, M. - \ 2014
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