Zebrafish as a translational model of Parkinson’s disease – a study of microRNAs

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, currently there are no disease modifying treatments. It is thought that microRNAs may be implicated in pathogenesis of PD. In this thesis the function of three microRNAs, which may be relevant to PD, were investigated in zebrafish. These miRNAs are: miR-133b, thought to be involved in development of dopaminergic neurons through its target PITX3; miR-205, which has been shown to regulate the PD-associated gene LRRK2; and miR-155, a key regulator of immune and inflammatory processes. Despite being more evolutionarily distant to humans than rodent models, the zebrafish has emerged as an effective model of human disease due it its low cost, fast development and transparency. A further aim of this thesis was to develop a high throughput imaging strategy to assess dopaminergic neuron number in the developing zebrafish brain, which can be used as a screening tool to identify potentially therapeutic compounds. The effect of both miR-133b and miR-205 knockdown on the number of dopaminergic neurons was investigated. In wild type zebrafish miR-205 knockdown causes a slight but significant decrease in dopaminergic neurons whereas miR-133b knockdown causes a significant increase in dopaminergic neuron number. In a previously established zebrafish model of PD, miR-133b knockdown completely rescued a 15% decrease in dopaminergic neuron number. The expression of miR-155 was assessed in three different zebrafish models of PD. While no change was observed in pink1- or parkin-deficient zebrafish, an increase in this miRNA and related inflammatory markers was observed in both larvae and juvenile brains of gba1-deficient zebrafish. As this miRNA and inflammatory markers are shown to be upregulated before any neuron loss is detectable in these zebrafish, it is possible that miR 155-related inflammation contributes to neurodegeneration. A stable miR-155 mutant line was also generated which will be used to determine whether genetic ablation of this miRNA has a protective effect in gba1-deficient zebrafish. A fluorescent reporter line expressing GFP in monoaminergic neurons has been validated for study of dopaminergic neurons. A fluorescence-based method developed using this line was able to reproduce data using a previously established in situ hybridisation-based method for neuron counting. To allow for more time and cost effective mounting of embryos for imaging, a mould has been developed. Use of this mould to mount embryos allows for high throughput imaging of the developing brain. The miRNAs presented in this study may have therapeutic potential in PD through modulation of dopaminergic neuron survival or by regulating the expression of PD-associated genes. The development of a high throughput screening process may allow a PD-related drug or toxin screen to be performed in our group in the near future

Biomass burning fuel consumption rates: a field measurement database

Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peerreviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha 1 with a standard deviation of 2.2),tropical forest (n = 19, FC = 126 +/- 77),temperate forest (n = 12, FC = 58 +/- 72),boreal forest (n = 16, FC = 35 +/- 24),pasture (n = 4, FC = 28 +/- 9.3),shifting cultivation (n = 2, FC = 23, with a range of 4.0-43),crop residue (n = 4, FC = 6.5 +/- 9.0),chaparral (n = 3, FC = 27 +/- 19),tropical peatland (n = 4, FC = 314 +/- 196),boreal peatland (n = 2, FC = 42 [42-43]),and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e. g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole biomes. Comparing the compiled FC values with co-located Global Fire Emissions Database version 3 (GFED3) FC indicates that modeling studies that aim to represent variability in FC also within biomes, still require improvements as they have difficulty in representing the dynamics governing FC

Degradation of communal rangelands in South Africa: towards an improved understanding to inform policy

In South Africa, the relative extent of range degradation under freehold compared to communal tenure has been strongly debated. We present a perspective on the processes that drive rangeland degradation on land under communal tenure. Our findings are based on literature as well as extensive field work on both old communal lands and ‘released’ areas, where freehold farms have been transferred to communal ownership. We discuss the patterns of degradation that have accompanied communal stewardship and make recommendations on the direction policy should follow to prevent further degradation and mediate rehabilitation of existing degraded land.Keywords: communal rangelands, land degradation, rehabilitation, social systemsAfrican Journal of Range & Forage Science 2013, 30(1&2): 57–6

United in Separation? Lozi Secessionism in Zambia and Namibia

Secessionism perseveres as a complex political phenomenon in Africa, yet often a more in-depth analysis is overshadowed by the aspirational simplicity of pursuing a new state. Using historical and contemporary approaches, this edited volume offers the most exhaustive collection of empirical studies of African secessionism to date. The respected expert contributors put salient and lesser known cases into comparative perspective, covering Biafra, Katanga, Eritrea and South Sudan alongside Barotseland, Cabinda, and the Comoros, among others. Suggesting that African secessionism can be understood through the categories of aspiration, grievance, performance, and disenchantment, the book's analytical framework promises to be a building block for future studies of the topic

Seasonal variation in the relative dominance of herbivore guilds in an African savanna

African savannas are highly seasonal with a diverse array of both mammalian and invertebrate herbivores, yet herbivory studies have focused almost exclusively on mammals. We conducted a 2-yr exclosure experiment in South Africa's Kruger National Park to measure the relative impact of these two groups of herbivores on grass removal at both highly productive patches (termite mounds) and in the less productive savanna matrix. Invertebrate and mammalian herbivory was greater on termite mounds, but the relative importance of each group changed over time. Mammalian offtake was higher than invertebrates in the dry season, but can be eclipsed by invertebrates during the wet season when this group is more active. Our results demonstrate that invertebrates play a substantial role in savanna herbivory and should not be disregarded in attempts to understand the impacts of herbivory on ecosystems

Victimisation in the lives of lesbian-identified women in South Africa : implications for clinical assessment and treatment

Few clinical studies have examined victimisation in the lives of lesbian women in South Africa and whether there are distinct implications for psychological treatment. This paper presents the assessment and treatment of a lesbian-identified South African survivor of childhood sexual abuse who, as an adult, was raped and later gang raped. Her victimisation in adulthood represented ‘corrective rape’ motivated by the prejudiced assumption that the sexuality of lesbian women is pathological and should be ‘corrected’ through rape. This paper lends insights into the role of heterosexism in shaping vulnerability to victimisation and the process of recovery. It provides recommendations for work with sexual minority clients and highlights the implications when there is an absence of safety and support in the external environment

Facilitation or Competition? Tree Effects on Grass Biomass across a Precipitation Gradient

Savanna ecosystems are dominated by two distinct plant life forms, grasses and trees, but the interactions between them are poorly understood. Here, we quantified the effects of isolated savanna trees on grass biomass as a function of distance from the base of the tree and tree height, across a precipitation gradient in the Kruger National Park, South Africa. Our results suggest that mean annual precipitation (MAP) mediates the nature of tree-grass interactions in these ecosystems, with the impact of trees on grass biomass shifting qualitatively between 550 and 737 mm MAP. Tree effects on grass biomass were facilitative in drier sites (MAP≤550 mm), with higher grass biomass observed beneath tree canopies than outside. In contrast, at the wettest site (MAP = 737 mm), grass biomass did not differ significantly beneath and outside tree canopies. Within this overall precipitation-driven pattern, tree height had positive effect on sub-canopy grass biomass at some sites, but these effects were weak and not consistent across the rainfall gradient. For a more synthetic understanding of tree-grass interactions in savannas, future studies should focus on isolating the different mechanisms by which trees influence grass biomass, both positively and negatively, and elucidate how their relative strengths change over broad environmental gradients. © 2013 Moustakas et al

“A Hideous Torture on Himself”: Madness and Self-Mutilation in Victorian Literature

This paper suggests that late nineteenth-century definitions of self-mutilation, a new category of psychiatric symptomatology, were heavily influenced by the use of selfinjury as a rhetorical device in the novel, for the literary text held a high status in Victorian psychology. In exploring Dimmesdale’s “self-mutilation” in The Scarlet Letter in conjunction with psychiatric case histories, the paper indicates a number of common techniques and themes in literary and psychiatric texts. As well as illuminating key elements of nineteenth-century conceptions of the self, and the relation of mind and body through ideas of madness, this exploration also serves to highlight the social commentary implicit in many Victorian medical texts. Late nineteenth-century England, like mid-century New England, required the individual to help himself and, simultaneously, others; personal charity and individual philanthropy were encouraged, while state intervention was often presented as dubious. In both novel and psychiatric text, self-mutilation is thus presented as the ultimate act of selfish preoccupation, particularly in cases on the “borderlands” of insanity