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Leiden, Netherlands

Brattstrom O.,Lund University | Brattstrom O.,Institute of Biology Leiden | AKesson S.,Lund University | Bensch S.,Lund University
Ecological Entomology | Year: 2010

The genetic differentiation in a migratory butterfly, the red admiral (Vanessa atalanta), was investigated to discern patterns of migratory routes used across Europe. AFLP profiles showed significant differences between almost all sampled locations, but there was no clear pattern of isolation-by-distance. Using the software STRUCTURE 2.2, we found two distinct genotype clusters present in different frequencies at all study sites. The frequencies of these genotypic clusters varied significantly between years within the same site. Remarkably few individuals were of mixed ancestry, indicating that some isolating mechanisms are present. Twenty-seven mtDNA haplotypes were identified but they showed no geographic structure, nor were they related to either of the two genotype clusters identified in the AFLP data. Most field observations of migrating red admirals suggest a regular north-south migration pattern in Europe. Our data indicate both long-distance migration and a more variable pattern in orientation, since the composition of the two genotypic clusters shows dramatic variation between sites and years in the northern part of the distribution range. © 2010 The Authors. Journal compilation © 2010 The Royal Entomological Society. Source

Roux O.,CNRS Functional Ecology & Environment Laboratory | Roux O.,French National Center for Scientific Research | Le Lann C.,CNRS Ecosystems, Biodiversity, and Evolution Laboratory | Van Alphen J.J.M.,CNRS Ecosystems, Biodiversity, and Evolution Laboratory | And 2 more authors.
Bulletin of Entomological Research | Year: 2010

Because insects are ectotherms, their physiology, behaviour and fitness are influenced by the ambient temperature. Any changes in environmental temperatures may impact the fitness and life history traits of insects and, thus, affect population dynamics. Here, we experimentally tested the impact of heat shock on the fitness and life history traits of adults of the aphid parasitoid Aphidius avenae and on the later repercussions for their progeny. Our results show that short exposure (1 h) to an elevated temperature (36°C), which is frequently experienced by parasitoids during the summer, resulted in high mortality rates in a parasitoid population and strongly affected the fitness of survivors by drastically reducing reproductive output and triggering a sex-dependent effect on lifespan. Heat stress resulted in greater longevity in surviving females and in shorter longevity in surviving males in comparison with untreated individuals. Viability and the developmental rates of progeny were also affected in a sex-dependent manner. These results underline the ecological importance of the thermal stress response of parasitoid species, not only for survival, but also for maintaining reproductive activities. Copyright © 2010 Cambridge University Press. Source

Agency: Narcis | Branch: Project | Program: Completed | Phase: Physics, Chemistry and Medicine | Award Amount: | Year: 2007

Transposable elements can jump from one location in the genome to another location via the activity of transposases, proteins that are encoded by the transposons itself. During this process transposons can be duplicated and they played an important role in the evolution of genomes. Not only resulted transposon amplification in the increase of genome size but during the transposition process new (chimeric) genes have been formed, which fulfill essential, yet unknown, cellular functions. DAYSLEEPER, a protein evolutionary related to hAT transposases, is essential for the development of Arabidopsis (Bundock and Hooykaas, 2005). Since amino acids crucial for transposition are lacking, it is unlikely that DAYSLEEPER has transposase activity. During evolution it has been domesticated by the host for alternative essential processes. Via its BED zinc finger DNA binding domain it can bind specific DNA sequences and an elevated expression level of DAYSLEEPER influences the expression of many other genes. However, the exact activity and function of DAYSLEEPER is unknown and the aim of this project is to obtain more insight in its role in plant development by performing the following experiments. The expression pattern and cellular localization will be determined. Binding site selection will reveal the optimal in vitro binding site and ChIP-on-chip experiments will reveal all in vivo binding sites. Interaction with other proteins will be studied. Furthermore, the occurrence of orthologs of DAYSLEEPER will be analyzed. We expect that the results will give more insight in the developmental processes in which DAYSLEEPER plays a role (expression pattern, cellular localization and complexes with other proteins) and in the activity of DAYSLEEPER (regulation of a few genes or influence on global chromatin structure).

Agency: Narcis | Branch: Project | Program: Completed | Phase: Physics, Chemistry and Medicine | Award Amount: | Year: 2007

Biological evolution critically depends on the generation of phenotypic variation by random mutations in the DNA of organisms. In 1859 Charles Darwin wrote Our ignorance of the laws of variation is profound. Effectively, this still holds today: phenotypic variation by random mutation is a black box in the Neo-Darwinian theory of evolution. Here, I propose an experimental project that opens this black box to yield profound new insights into the evolution of life and new tools for biotechnology. Before a new phenotype can evolve through natural selection, it must first emerge via random mutations. Genetic mutations are translated into phenotypic variation according to the genotype-phenotype map (GP-map). What are the properties and evolutionary consequences of the GP-map? This fundamental question has long been impossible to answer due to the lack of a suitable conceptual framework. Recently, a number of ground-breaking theoretical studies provided a basis for ending this impasse. They predict that, despite its complexity, the GP-map has general properties that affect evolution and can be quantified. This resulted in testable hypotheses on how robustness and evolvability ? both central problems in contemporary biology ? emerge from the GP-map, and can themselves evolve. Building on this, I propose a series of innovative experiments that (i) characterize the GP-map, (ii) determine its evolutionary consequences and (iii) examine the robustness and evolvability hypotheses. This will be achieved by systematic measurement of the phenotypic neighbourhoods of neutral genotypes and by artificial selection experiments using bacterial model systems: Bacillus subtilis sporulation and genetic toggle switching in Escherichia coli. I will deliver the first empirical datasets allowing the timely evaluation of the new theory. As a spin-off, the research yields tools for synthetic biology: an applied field aiming to engineer phenotypes for medicine and biotechnology. The multidisciplinary strategy is supported by collaborations with national and international experts.

Leslie N.R.,Heriot - Watt University | Den Hertog J.,University Utrecht | Den Hertog J.,Institute of Biology Leiden
Cell | Year: 2014

Tumor suppressors block the development of cancer and are often lost during tumor development. Papa et al. show that partial loss of normal PTEN tumor suppressor function can be compounded by additional disruption caused by the expression of inactive mutant PTEN protein. This has significant implications for patients with PTEN gene mutations. © 2014 Elsevier Inc. Source

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