Heat stress (HS) caused by above-optimal temperatures adversely affects plants’ growth and development and diminishes crop yields. In natural and agricultural environments, these stresses are often... Show moreHeat stress (HS) caused by above-optimal temperatures adversely affects plants’ growth and development and diminishes crop yields. In natural and agricultural environments, these stresses are often transient but recurrent and may progressively increase in severity over time. In addition to the inherent ability to cope with a single HS event, plants have evolved mechanisms that enhance their capacity to survive and reproduce under such conditions. This involves the establishment of a molecular ‘thermomemory’ after moderate HS that allows them to withstand a later — and possibly more extreme — HS event. Here, I summarize the current understanding of the molecular and biochemical mechanisms underlying thermomemory across multiple cellular levels and discuss aspects that require further attention. Show less
Anthropogenic noise negatively affects wildlife in a wide range of taxonomic groups. Especially for birds, a substantial number of observational studies have now shown negative associations between... Show moreAnthropogenic noise negatively affects wildlife in a wide range of taxonomic groups. Especially for birds, a substantial number of observational studies have now shown negative associations between noise pollution and abundance and diversity along roadsides. Researchers investigating birds’ behavioural responses to high level noise to date have mostly focused on the immediate adjustment of vocal signalling behaviour. However, there is more than one mechanism by which birds might cope with increasing noise levels. They may show immediate behavioural reactions, such as spatial avoidance and/or vocal adjustment, but also more ontogenetic adjustments with long-term consequences like changes in sensory and personality traits. To test these potential effects of traffic noise on birds, I conducted a series of experiments using zebra finches. I have demonstrated that traffic noise per se can contribute to spatial avoidance in birds and cause variation in parental behaviour, and that there can be changes in noise avoidance behaviour in the course of a lifetime. These results provide new insights into the potential impacts of noise on birds. Show less
Drongelen, R. van; Vazquez-Faci, T.; Huijben, T.A.P.M.; Zee, M. van der; Idema, T. 2018
A key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of... Show moreA key process in the life of any multicellular organism is its development from a single egg into a full grown adult. The first step in this process often consists of forming a tissue layer out of randomly placed cells on the surface of the egg. We present a model for generating such a tissue, based on mechanical interactions between the cells, and find that the resulting cellular pattern corresponds to the Voronoi tessellation of the nuclei of the cells. Experimentally, we obtain the same result in both fruit flies and flour beetles, with a distribution of cell shapes that matches that of the model, without any adjustable parameters. Finally, we show that this pattern is broken when the cells grow at different rates. Show less
The main focus of the research that makes up this thesis was to translate rodent behavioural assays to larval zebrafish for better time and resource management in biomedical research,... Show moreThe main focus of the research that makes up this thesis was to translate rodent behavioural assays to larval zebrafish for better time and resource management in biomedical research, pharmaceutical research and development. __The larval zebrafish is a useful model in toxicology and drug discovery. However, its predictivity is restricted by compound class. __Light-dark cycle plays an important role in the normal development of the zebrafish embryo, and abnormal lighting regimes during rearing can result in malformations. __The hyperactivity displayed by zebrafish larvae following the onset of sudden darkness is an intrinsic characteristic. Zebrafish larvae quickly habituate with repeated stimuli of onset of darkness with short interstimulus interval. __Zebrafish larvae are able to discriminate colours, and they show a preference for orange and green, but aversion towards red, yellow, blue and black. The larvae also show freezing behaviour in the complex environment which is attenuated with diazepam.. __Zebrafish larvae raised in an abnormal lighting regime changed some aspects of their colour preference, although orange and red remained as preferred and avoided colours respectively. __In short, the zebrafish larvae is a useful complementary animal model in behavioural research amenable to high-throughput screening of compounds and drug discovery Show less
This thesis provides a comparison of mostly perceptual development during vocal learning in songbirds (zebra finches) and human infants. The aim is to disentangle experience dependent and... Show moreThis thesis provides a comparison of mostly perceptual development during vocal learning in songbirds (zebra finches) and human infants. The aim is to disentangle experience dependent and independent processes during vocal learning. In both human infants and juvenile songbirds, a perceptual preference for __universal__ sounds was found, independent of adult auditory input. Later in development, both infants and juvenile songbirds show a change is preference. The juvenile songbirds clearly change their preference towards sounds they have been auditorily exposed to (chapter 3). In human infants in the influence of experience is less clear in this thesis. In combination with previous literature the most likely scenario is a combination of experience dependent and independent processes (chapter 2). To further compare human and birdsong phonology, a __typology__ of zebra finch song elements was performed (chapter 4). The results of this study indicate commonality as well as variation between populations in terms of phonology. In the order of elements within a sequence however, there is little evidence for common patterns across populations and there is variation within and between populations. In summary, this thesis shows similarities in developmental mechanisms in two vocally learning species. There might be a link between development and typology. Show less
In this thesis the evolutionary background, function and localization of the domesticated transposase DAYSLEEPER are described. We found that DAYSLEEPER-like genes can be found in angiosperms, but... Show moreIn this thesis the evolutionary background, function and localization of the domesticated transposase DAYSLEEPER are described. We found that DAYSLEEPER-like genes can be found in angiosperms, but not in lower plants. We also found that DAYSLEEPER interacts with several proteins and is probably involved in regulating protein degradation through involvement in ubiquitin-mediated protein degradation. Show less
The research described in this thesis mainly focussed on making and refining a model that describes axial patterning during gastrulation in the frog Xenopus laevis. Chapter 2 and 3 describe that... Show moreThe research described in this thesis mainly focussed on making and refining a model that describes axial patterning during gastrulation in the frog Xenopus laevis. Chapter 2 and 3 describe that axial information arises in the mesoderm and subsequently in the neurectoderm. Also is shown that this information, under influence of the Spemann organiser and cellular movements, is translated from a time sequence into a space sequence. The function of the Spemann organiser, important for AP patterning is neural induction. In chapter 4 is described that retinoids, important for axial patterning and formed in the mesoderm, have a patterning effect on neurectoderm. An important conclusion in this chapter is that retinoids are candidates for transfer of axial information from mesoderm to neurectoderm and can, in this way, coordinate the expression of axial information between mesoderm and neurectoderm. In chapter 5 a study is described where the transcriptional targets of Hoxc6 or Antennapedia in the frog Xenopus laevis and the fruitfly Drosophila melanogaster are compared. From this comparison conclusions can be drawn about the processes that are important for the function of Hoxc6/Antp. From this study could be concluded that celldivision, cellmigration, and suppresion of head formation are processes that are important for the function of Hoxc6/Antp. Show less
