During adolescence, animals leave the natal home and interact with potentially threatening stimuli (i.e. stressors), e.g. unfamiliar environments and conspecifics. Adolescent stressors can result in fewer interactions with unfamiliar stimuli in adulthood, plausibly due to sustained effects of glucocorticoid exposure on stress physiology (e.g. glucocorticoid secretion and receptor expression). The current thesis tested the hypothesis that adolescent glucocorticoid exposure and social experiences act as stressors by quantifying the effects of the adolescent experiences on behavioural responses to unfamiliar stimuli and the underlying neuroendocrine mechanisms when in adulthood using two captive species, zebra finches and rats. In study one, adolescent zebra finches were dosed with the glucocorticoid corticosterone. In adulthood, birds dosed with corticosterone in early adolescence took longer to enter an unfamiliar environment when tested individually and had lower expression of the glucocorticoid receptor GR in the hippocampus and hypothalamus, brain regions that regulate stress responses. Glucocorticoids therefore appear to be an endocrine mechanism behind the long-term effects of adolescent stress. Subsequent studies explored whether higher social density and more unfamiliar social interactions during adolescence act as stressors. In study two, early adolescent zebra finches were housed in groups varying in conspecific number and density. In adulthood, females raised in larger groups secreted a higher stressor-induced corticosterone concentration and, if raised at lower density, spent more time in an unfamiliar environment when group housed. In study three, adolescent female rats were housed in familiar pairs or exposed to unfamiliar conspecifics. Unfamiliar adolescent interactions had no effects on responses to unfamiliar environments or stress physiology in adulthood, but heightened ultrasonic call rates. In this thesis, adolescent social experiences do not act like stressors, but modulate (especially female) social behaviour. Adolescent stressors and social experiences therefore have distinct effects on responses to unfamiliar stimuli and stress physiology that are maintained into adulthood.

A surge of recent work elucidating a role for learning and memory in avian nest-building behaviour has challenged the long-standing assumption that nest building develops under genetic control. Whereas that work has been addressed at describing the cognitive mechanisms underpinning nest-building behaviour, almost nothing is known about either the neurobiological processes controlling nest building or the selection pressures responsible for the diversity in avian nest-building behaviour. Here, I sought to identify both the neural substrates involved in nest-building behaviour and some of those selection pressures. First, I used expression of the immediate early gene product Fos, an indirect marker of neuronal activity, to identify brain regions activated during nest-building behaviour in the brains of nest-building and control zebra finches (Taeniogypia guttata). I found that neural circuits involved in motor control, social behaviour, and reward were activated during nest building. Furthermore, I found that subpopulations of neurons that signal using the nonapeptides vasotocin and mesotocin and the neurotransmitter dopamine located within some of these neural circuits were also activated during nest building, suggesting these cell-signalling molecules may be involved in controlling nest-building behaviour. Next, I found that variation in the amount of folding in the cerebellum, a brain structure thought to be involved in manipulative skills, increased with increasing nest structural complexity, suggesting that the cerebellum is also involved in nest building. Finally, using evolutionary statistical models, I found support for the hypothesis that nest-site competition off-ground and increased predation pressure on the ground in Old World babblers (Timaliidae) led to the co-evolution of building domed nests on the ground. Here, then, I provide the first evidence of potential neural substrates controlling and selection pressures contributing to variation in nest-building behaviour.

My graduation thesis is called {\clq}qCrocks of Safari`` and it is divided into two main segments. The First part is theoretical which explains my inspiration, choice of theme and material, method of working - starting with design, ending with final artwork and its installation. It also considers the techniques of mosaic creation. It includes image documentation, which enriches and completes the text. The Second part is practical which includes its own graphic creation. That is two mosaic images made out of combined material {--} ceramics and glass (mirror) inserted into a metal frame. It features graphic structures and elements of an African fauna. It specifically interprets cut outs from herd of zebras and their typical stripes. My goal was to create abstract images where you can feel the character of used material and harmony of natural structures.

Hipopituitarismo congênito é caracterizado por deficiência hormonal múltipla devido a mutações de fatores de transcrição envolvidos na embriogênese hipofisária. As células-tronco estão presentes na hipófise e são caracterizadas por dar origem a uma célula progenitora e uma célula indiferenciada por divisão assimétrica. Estão envolvidas na hipófise em processos de alta demanda metabólica em diferentes fases da vida. Em estudos prévios, observou-se o acúmulo dos marcadores de células-tronco Sox2 e Nr2e1 no camundongo Ames, que apresenta mutação no gene Prop1. O Sox2 é o marcador consenso de células-tronco na hipófise enquanto que o Nr2e1, nunca antes caracterizado na hipófise, é essencial para a manutenção de células-tronco e neogenese no cérebro. A perda de função deste gene pode causar agressão e falta de instinto materno em camundongos. Com isso, o objetivo desse projeto foi utilizar o animal modelo zebrafish para avaliar o papel repressor do gene prop1 e caracterizar o gene nr2e1 bem como, confirmar se o mesmo está envolvido com a diferenciação terminal na hipófise, e sua interferência no comportamento do animal mutado. O zebrafish se encaixa adequadamente nesse projeto pois é de fácil manutenção, econômico e com rápido desenvolvimento. No presente estudo criou-se 2 modelos de zebrafish utilizando-se a técnica de edição genômica conhecida como CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) para nocautear os genes prop1 e nr2e1. Esta técnica permite uma interrupção específica e substituição de bases no genoma, resultando em uma alta especificidade, baixa toxicidade celular e é herdável. O zebrafish homozigoto com mutação no gene nr2e1 se desenvolve e reproduz como o animal controle, porém apresenta um comportamento mais exploratório quando comparado com o animal selvagem e o heterozigoto. A imunofluorescência para o anticorpo Sox2 no animal mutado mostrou se diferente do selvagem, pois apresenta um aumento da expressão temporal e o mesmo não se colocaliza com o Nr2e1. A imunofluorescência feita com os hormônios não se mostrou diferente entre o mutado e o selvagem. Conclui-se diante dos achados de normalidade do desenvolvimento, fertilidade, ausência de co-localização com o gene Sox2 e presença de hormônios como Tsh, Fsh e Gh, que o gene nr2e1 não é crucial na diferenciação terminal na hipófise porém o animal mutado apresenta um comportamento diferente do animal selvagem. Os resultados da caracterização do zebrafish com mutação no gene prop1 ainda estão em andamento devido a dificuldade de se estabelecer essa linhagem / Congenital hypopituitarism is characterized by multiple hormone deficiencies due to mutations in transcription factors involved in pituitary embryogenesis. Stem cells, which by definition can each give rise to a progenitor and an undifferentiated cell by asymmetric division, are present in the pituitary gland and are important during periods of high metabolic demand in different phases of life. In previous studies, the accumulation of the stem cell markers Sox2 and Nr2e1 was observed in the Ames mouse, which harbors a mutation in Prop1. Sox2 is the consensus stem cell marker in the pituitary gland, while the role of Nr2e1 in the pituitary development has not been characterized although it is essential for neural stem cell maintenance and neogenesis in the brain and its loss of function causes pathological aggression and lack of maternal instinct in mice. In this project, the zebrafish animal model was used to characterize the role of nr2e1, to confirm whether this gene can be involved in the pituitary terminal differentiation, and to determine the effects of this gene on animal behavior. The zebrafish is a particularly appropriate model for use in this project because it is easy to maintain, is economical, and has a rapid metabolism and growth rate. In the present study, we created 2 zebrafish models by knocking out prop1 and nr2e1 using the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) genome-editing technique. This technique enables highly specific gene/reading frame interruption and/or base substitution in the genome, with low cellular toxicity and high heritability. Zebrafish with homozygous nr2e1 mutations develop and reproduce similarly to wild-type zebrafish, but present a more exploratory behavioral pattern compared to wild-type and heterozygous zebrafish. Based on immunofluorescence, Sox2 expression was higher in the mutant zebrafish than in the wild type and was not co-localized with Nr2e1 expression. Hormone expression did not differ between wild-type and mutant zebrafish. We conclude that nr2e1 is not crucial in the terminal differentiation of the hormone-forming pituitary gland; however, it induces a distinct behavioral phenotype at the larval stage. Analyses of zebrafish harboring a prop1 mutation are ongoing owing to issues with the establishment of the lineage

Les connexions neuronales du système visuel forment des synapses spatialement distribuées en couches discrètes. Comprendre la base du ciblage spécifique axonale est critique pour déchiffrer la formation des réseaux neuronaux complexes. Dans une première étude, nous avons investigué le rôle de la protéine de la matrice extracellulaire Reelin dans la formation in vivo du circuit rétinotectal chez le poisson zèbre. Ce circuit se compose de cellules ganglionnaires de la rétine (CGRs) transmettant l’information visuelle au cerveau via la projection de leur axone dans les différentes couches du tectum optique. Nous avons démontré que la Reelin secrétée par de neurones inhibiteurs localisés dans les couches supérieures du tectum optique forme un gradient. L’induction de mutations délétères dans la voie de signalisation canonicale de la Reelin à l’aide d’outils génétiques a conduit à des défauts de ciblage des axones de CGRs. Nos résultats démontrent un nouveau rôle de la Reelin lors du développement du système visuel et la décrivent comme signature moléculaire nécessaire au ciblage et au positionnement précis des axones de CGRs.Dans une seconde étude, nous avons utilisé la technique CRISPR/Cas9 pour développer une nouvelle approche de mutagénèse conditionnelle chez le poisson zèbre. Nos résultats démontrent que la perturbation de gènes dans des tissues spécifiques peut être effectué par l’induction de l’expression de la protéine Cas9 via le système Gal4/UAS. Nous avons établis un outil pour induire l’apparition de mutations délétères dans des clones de cellules mais aussi dans des cellules individuelles, tous pouvant être suivit distinctement grâce à un marquage génétique. / Neuronal connections in the visual system are arranged in synaptic laminae. Understanding the basis of lamina-specific axonal targeting is critical to gain deeper insights on how complex neural networks form. In a first study we investigated the role of the ECM protein Reelin during zebrafish retinotectal circuit formation in vivo. Here retinal ganglion cells (RGCs) convey the visual information to the brain by projecting their axons to different layers of the optic tectum. We demonstrated that Reelin secreted by a specific class of tectal superficial inhibitory neurons is spatially distributed in a superficial-to-deep gradient within the tectal neuropil. Induced gene disruption for all the components of the canonical Reelin pathway expressed in the retinotectal system resulted in aberrant layering of RGC axons suggesting a role for Reelin pathway in axonal sublaminar segregation. Altogether our findings elucidate a new role for Reelin in vertebrate visual system development, during which it acts as molecular cue by imparting positional information for ingrowing RGCs.In a second study we took advantage of the CRISPR/Cas9 technology to develop a novel approach for conditional mutagenesis in zebrafish. Our results provide evidence that tissue-specific gene disruption can be achieved by driving Cas9 expression with the Gal4/UAS system. We established a tool to induce loss-of-function mutations in cell clones or single cells that can be followed by genetic labeling, enabling their phenotypic analysis. Our technique has the potential to be applied to a wide-range of model organisms, allowing systematic mutagenesis and labeling on a genome-wide scale.

The phenotype-linked fertility hypothesis predicts that both, male carotenoid-based sexual ornamentation and their spermatozoa are phenotypically plastic and may be co-affected by the environment. One of the factors affecting their phenotype may be oxidative stress and the ability of organism to eliminate its effect. Oxidative stress may reduce sperm quality because sperm lack the ability to repair DNA, but it can also affect spermatogenesis itself. However, some substances may function as antioxidants, and thus eliminate effect of reactive oxygen species (oxidative stress) in the body. In this study, adult zebra finch males (Taeniopygia guttata) originating from the domesticated and recently wild-derived populations were exposed to the diquat (D), which enhances the oxidative stress, and carotenoid lutein (L), which could have an antioxidant function. Experimental design had factorial character 2x2 with a control (group L, D, LD, control). Neither oxidative stress, carotenoids, nor their interactions affected sperm morphology or velocity and it also did not increase abnormal sperm proportion in the ejaculate. However, the differences were observed at the molecular level, where by inducing the oxidative stress, the sperm had reduced signal intensity of acetylated α-tubulin in the sperm tails....

The Allideghi Wildlife Reserve in the Amibara District of Afar Regional State, Ethiopia, has international significance for harboring endangered Grevy's Zebra and other wildlife dependent on grasslands. The reserve is increasingly used by pastoral people and their herds. Impacts of livestock on native vegetation include direct effects of grazing and indirect effects from livestock-facilitated dispersal of an invasive plant, Prosopis juliflora. The main research objective was to determine effects of pastoralism and vegetation change on prospects for sustaining the Allideghi Wildlife Reserve as grassland habitat for Grevy's Zebra. Methods included use of driving surveys to quantify resource use by herbivores, vegetation analysis, and engagement with local people. Resource-use patterns of livestock across the Allideghi grassland were often positively affected by proximity of water, while that for wild ungulates was often negatively affected by proximity of people. Livestock concentration at a major borehole has created a large piosphere with concomitant reductions in herbaceous standing-crop, productivity, and species richness; plant species have shifted from grasses to forbs in severely grazed sites. Vegetation further from the borehole was resilient in response to moderate grazing pressure in terms of species composition and productivity. Since being introduced at a nearby commercial plantation in the 1970s, P. juliflora has been dispersed to the Allideghi Wildlife Reserve via livestock; cattle, sheep, and goats eat the pods and deposit seeds in manure at settlements and favored foraging areas. Prosopis juliflora greatly reduced species richness and basal cover of native herbaceous vegetation in the Allideghi grassland. Analysis of remotely sensed images from the past 30 years indicated major land-use change in the district due to agricultural expansion as well as land-cover change due to Prosopis encroachment and heavy grazing. Recent efforts have been undertaken by various agencies to control P. juliflora, via harvest in the district, but this has yielded variable and often negative results. Without a concerted effort to limit livestock grazing and control spread of P. juliflora, the future for the grassland and wildlife at the Allideghi Wildlife Reserve is grim. Agencies and policy makers need to promote science- and community-based approaches to help rectify the situation. (311 pages)

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Många gående skadas eller dör i trafiken varje år. En stor del av olyckorna inträffarvid övergångsställen, flest olyckor sker vid obevakade övergångsställen. Nollvisionenär ett långsiktigt mål att ingen människa ska behöva skadas eller dö itrafiken. Somett ytterligare steg mot  nollvisionen infördes år 2000 den så kallade”Zebralagen”, en lag som innebär att fordonsförare har väjningsplikt gentemotgående. Eftersom denna lag är aktuell i samhällsdebatten har vi valt attstudera hur lagen efterlevs i praktiken detta genom att observera fyra olikatyper av övergångsställen vid sammanlagt 14 olika tillfällen och olika tider pådygnet (vardagar mellan 6-20). För att kunna jämföra observationerna medförares och fotgängares påstådda agerande har även 100 stycken enkäter delatsut och sammanställts. Utifrån dessa studier och sammanställningar har vi kommitfram till resultatet att människor upplever sig själva vara betydligt meruppmärksam och skötsamma i trafiken än vad de egentligen är och även attutformningen på övergångsstället har stor påverkan på fordonsförarna men ingenalls på fotgängarna. / Many people walking in traffic gets injured or killed in traffic each year. The place where this occurs mostly is on zebra crossings, the ones that have no surveillance are the ones where the accidents are most common. A vision zero has been establish to create a long term goal to make sure that no persons gets injured or killed in traffic. To enhance vision zero has a “zebra law” been instate year 2000, the law states that cars needs to give way for people walking. This law has been discussed in media and that is why we want to do this research about it. We did the research through observation at four different zebra crossings during 14 different times and different times of the day, all between 6 am and 8 pm. To get the people who is walking and the drivers opinions about their experiences in traffic was a survey answered by 100 participants and then analysed conducted and analysed with 100 participants. The results shows that people believe that they are more observant in traffic then what the observations has shown is true. The design of the zebra crossings did also play a role in how observant the drivers were but did not have the same effect on the people walking.