Public transport policy in the Netherlands

Dutch public transport as a part of transport policy.Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

Characterizing Liquid-Liquid Phase Separation

The process of liquid-liquid phase separation (LLPS) has been explored in polymer physics and colloidal science, and recently, researchers have studied this process to better understand intracellular organization. LLPS is the process by which a liquid mixture will separate into two fluid phases. Currently, many research labs are working to understand how and why certain cellular organelles are liquid bodies that are the result of phase separation. Investigations of how the cell uses phase separation to organize and compartmentalize has demonstrated a wealth of biological implications. We experimentally study the process of de-mixing in a model system in order to define better ways of analyzing and characterizing the physical properties of the two fluid phases. Our experiments utilize the following optical methods: phase contrast microscopy for video analysis of droplets merging to determine capillary velocity; fluorescence recovery after photo-bleaching (FRAP) to determine the diffusion coefficient; particle tracking to determine viscosity; and confocal z-scans to determine the density difference between two phases. By assessing methods to study the physical features of these droplets, like surface tension, viscosity and density, optimal methods can be applied to study membrane-less organelles assembled in cells via LLPS

Examination of Methylation Status and Occupancy of DNA Methylation Modifying Proteins on Regulatory Regions of the DAX-1 Gene

Epigenetic modifications influence gene expression and thereby play a pivotal role in development and disease. Misregulation and mutations in the DAX-1 gene, or Dosage-Sensitive Sex Reversal, Adrenal Hypoplasia Congenita, Critical Region on the X chromosome, gene 1, have been implicated in Adrenal Hypoplasia Congenita (AHC) and Dosage Sensitive Sex Reversal (DSS). The orphan nuclear hormone receptor DAX-1 is expressed predominantly in tissues such as the testes, ovaries, breast, adrenal cortex, and lung. Critically, DAX-1 may serve as an indicator of aberrant growth in these tissues. Here we hypothesize that DAX-1 is epigenetically regulated, specifically in cancer cells, thereby reducing its expression. In a survey of several human cancer cell lines, the methylation status of the promoter region of DAX-1 was investigated in order to determine whether epigenetic control played a role in repressing DAX-1 gene expression. Through molecular techniques such as qPCR and western blots, differential expression of DAX-1 in human cell lines was confirmed. Additionally, methylation specific restriction enzyme analysis and bisulfite sequencing identified the location of methylation in breast, adrenal, lung, liver, and kidney cancer cell lines. Following these experiments, a correlation of the methylation status of the DAX-1 promoter and DAX-1 expression is evident. In tandem with bisulfite sequence analysis, chromatin immunoprecipitation experiments elucidated a primary region of interest in which methylation may be critical to the silencing of DAX-1 gene expression. Centered around the transcriptional start site, a stark difference in methyl binding protein occupancy between cancerous and noncancerous breast tissue was identified and likely plays a critical role in gene repression via methylation. Ultimately, this research aims to elucidate the role of epigenetic regulation in gene expression as well as further our understanding of the role of DAX-1 in human cancers

Early feather pecking as a form of social exploration:the effect of group stability on feather pecking and tonic immobility in domestic chicks

In two lines of White Leghorns that differ in their propensity to feather peck, feather pecking was already present I day after hatching. A significant line difference developed within 3 days and this difference remained in the following weeks. There was no clear relationship between feather pecking and ground pecking, instead feather pecking was associated with other socially orientated pecks. When chicks were confronted with feathers as an inanimate stimulus pecking at these feathers did not reflect pecking in a social context. These results suggest that feather pecking has an underlying social component, rather than being a redirected behaviour. To test the influence of social factors on feather pecking, chicks from the high feather pecking line were subjected to regular rehousing or regular rehousing plus confrontation with unfamiliar peers. Gentle feather pecking increased significantly in,or, cups that were rehoused with unfamiliar peers. Directly after confrontation chicks displayed a preference in the total number of pecks toward these unfamiliar birds. Gentle feather pecking as a separate pecking orientation showed a similar trend. Increased righting times in a tonic immobility test were recorded in the experimental groups, hence frequent confrontation with unfamiliar peers may be experienced by chicks as stressful, which is consistent with the hypothesis that stress mediates the expression of feather pecking. In contrast to the dominant hypotheses in the field, we argue that gentle feather pecking at an early age plays an important role in the building (social exploration) and maintenance of social relationships between chicks. (C) 2002 Elsevier Science B.V. All rights reserved

Ejaculate testosterone levels affect maternal investment in red junglefowl (<i>Gallus gallus gallus</i>)

Substantial concentrations of testosterone are not only present in a male's circulation, but also in its ejaculate. Surprisingly, the regulation of ejaculate T and its effects on females and their offspring, potentially a cryptic paternal trait, are not known. We found lower circulating and higher ejaculate T concentrations in subordinate red junglefowl (Gallus gallus gallus) males compared to dominant males, suggestive of an adaptive trade-off in T allocation to circulation and their ejaculate. Subsequently, we artificially inseminated females with either testosterone enriched (TE) or control ejaculates (CE) in a cross-over design. TE females produced heavier eggs than CE females. Offspring growth and tonic immobility were affected in a sex-specific way by TE. TE sons were heavier with shorter TI duration than CE sons, and TE daughters were lighter than CE daughters but daughters did not differ in TI score. However, the chicks competitiveness was not influenced by the TE nor CE. This indicates a previously unknown function of ejaculate testosterone as well as a new form of interaction between a cryptic paternal trait and a maternal effect that may be widespread in the animal kingdom

The relationship between male social status, ejaculate and circulating testosterone concentration and female yolk androgen transfer in red junglefowl (<i>Gallus gallus</i>)

Several studies show that avian females prefer males based on their secondary sexual ornaments and dominance status. We tested in red junglefowl (Goth's gallus) how comb size affected the result of fighting and how the dominance status related to testosterone concentrations in their circulation and ejaculates. We subsequently tested how social status was related to female reproductive investment, including yolk hormone transfer. We found that after a fight 1) winners increased plasma T and decreased ejaculates T whereas losers' T remained unchanged, and 2) plasma T of winners was higher but ejaculates T was lower than those of losers. We argued those are consistent with the different reproductive strategies of dominant and subordinate males. Furthermore, in line with offspring sex-dependent growth patterns females transferred significantly more androstenedione to female than male embryos when mated with winners, while doing the opposite when mated with losers. We concluded therefore that female reproductive investment was affected by both partner quality and embryo sex. The results indicate that male quality influences sex-specific maternal investment, which could be mediated by ejaculate testosterone concentration

Increased exposure to yolk testosterone has feminizing effects in chickens, Gallus gallus domesticus

Competing for food by altricial and semiprecocial bird nestlings is a behaviour well known for its sensitivity to maternal androgens during prenatal development. Whether a similar effect is present in precocial species that do not beg is less well known. We therefore increased yolk testosterone levels within the physiological range at the onset of incubation to study its effects on food competition behaviour in the domestic chicken, Gallus gallus domesticus. We found an increase in competitiveness in testosterone-treated male domestic chicks, raising their level to that of the females. This is in line with the decrease in circulating plasma levels of males in the direction of the levels in females, and the overall decrease in androgen receptor densities after prenatal treatment as found previously. Hormones are known to have long-lasting organizing effects on behaviour and to affect sexual differentiation in vertebrates. Although research into hormone-mediated maternal effects has been productive, only a few studies describe (the ambiguous) effects into adulthood. Therefore we followed our animals into adulthood and recorded androgen-dependent social behaviour and secondary sexual characteristics, body mass and circulating plasma testosterone levels and checked whether these variables were treatment dependent. Treatment had a near significant effect on comb colour (both brightness and chroma). Again treatment caused a shift towards a more female-like phenotype. This suggests that, in contrast to earlier suggestions, maternal androgens may interact with (but not disrupt) sexual differentiation of brain and behaviour and the development of secondary sexual characteristics.

A tangle near silence

This thesis is a byproduct of a program of artistic practice research in which I used quiet sound to orient experience towards entanglement. My understanding of entanglement speculatively mingles Donna Haraway’s sympoiesis, Karen Barad’s intra-action, and Gilbert Simondon’s transindividuation, and finds further company in the process philosophies of Brian Massumi and Henri Bergson, the queer phenomenology of Sara Ahmed, and the everyday aesthetics of Yuriko Saito. My artistic research began by continuing my practice of composing music that used extreme quiet in a performance setting to encourage embodied sensitivity to acoustic, physical, and social environments. My experimentations quickly broadened, partly owing to the pandemic, to include more diverse situations and practices. Thanks to the refractive and reflexive capacities of practice research, I investigated entanglement and process in my own experience as well as in the experiences I contributed to with my works. As a result, notions of speculation, discovery, byproduct, and feedback became central to my understanding of what it means to, in Haraway’s terms, ‘stay with the trouble’. In addition to various sonic exercises, software tools, situated techniques, and scraps of wood, as well as this thesis, my practice research produced a number of artworks: the compositions Pith for solo violoncello, Common for three players on one concert bass drum, and Ripples for solo percussionist; the interactive web scores What’s at Hand and Revelling in Mists of Constellations of Pine Points and Waltzes; the wandering public sound installation Pathside Box; and the self-constructed tactile feedback sculpture Haptic Box