In this project I have tried to obtain stable transformants of Drosophila melanogaster flies using electroporation. I have completed approximately 200 tests using different DNA concentrations, voltages and cuvettes, including a novel Petri dish cuvette which I developed and manufactured myself. I also developed new and more efficient procedures of egg collection and egg dechorionation. Although I was not  successful in obtaining true stable transformants, control experiments indicate that electroporation of DNA into embryos could be accomplished under the conditions used. The lack of stable transformants was probably due to failure of the electroporated DNA to integrate into the host genome. The reasons for why the DNA did not integrate was not further investigated in this study.

Synovial joints enable frictionless movement between the adjacent bones. Lubricating fluid enclosed within the joint reduce the pressure to allow free movement. Previously synovial joints have been associated with a terrestrial life and have mainly been studied in tetrapods, such as mammals and chicken, under the assumption that the joint did not evolve before animals adapted to a life on land. However, a recent study described the production and function of lubricin in the jaw and pectoral fin joints in ray-finned fishes, such as zebrafish, suggesting previous assumption to be questionable. The current study aim to further investigate the jaw joints in the ray-finned zebrafish, by examininge the morphology and presence of specific cell types, called synoviocytes, associated with the synovial joint. The synoviocytes are divided into two groups: macrophage-like cells and fibroblast-like cells. Tissue sections were histologically investigated with nuclear staining and immunohistochemically with antibodies to chondroitin sulphate (CS-56) and uridine diphosphoglucose dehydrogenase (UDPGD, UGDH) to investigate the presence of fibroblast-like cells. Small and circular cells were observed in the joint line and surrounding cartilage nascent to the joint. These cells could not be identified as chondrocytes or part of the perichondrium, and their UDPGD activity witness on similarities to the fibroblast-like cells. UDPGD is associated to the synthesis of hyaluronan (HA) which plays a key role in joint cavitation, hence, suggesting functional similarities in the development of zebrafish jaw joint to synovial joints. Furthermore a double transgenic zebrafish, fli1:EGFP/mpeg1:mCherry, was used to examine the presence of macrophages within the joint area. Macrophages were observed on the surface of the jaw joint in close association with blood vessels but did not show signs of incorporation within the joint. These results present further similarities of joints in ray-finned fish to the synovial joint but also the need to further examine similarities in order to understand the development and evolution of the joints. The possibility to implement the zebrafish model would facilitate future studies on the healthy synovial joint as well the diseases related to it.

Gastric ulceration (Equine gastric ulceration syndrome, EGUS) is a common disease among today's domesticated horses (Equus caballus), but can also occur in wild horses. Horses naturally spend 60 - 70 % of the day grazing and foraging; therefore, their gastrointestinal tract is designed for continuous forage and the gastric juice is secreted continuously. When the interval between forage provision is over 6 hours, the pH level in the stomach tends to drop below 4, which damages the gastric mucosa. The stomach of a horse is divided into two parts, an upper part which is sensitive to gastric juice and a lower part which is used to it. Despite this, gastric ulceration can occur in both parts of the stomach, though for different reasons. The most common cause of gastric ulceration in the lower part of the stomach is mainly linked to stress, while in the upper part it is due to feeding routines and feed content. Racehorses, trotter and galloping horses are the type of horse where gastric ulceration is most common, the prevalence being as high as 80 – 100 % during the competition season. Gastric ulceration is a disease with diffuse symptoms and there are several different reasons for its appearance, which are also often in combination with each other. More research is needed on the subject, especially regarding gastric ulceration in the lower part and why this occurs. / Magsår är vanligt förekommande bland dagens domesticerade hästar (Equus caballus) men kan även förekomma bland vilda hästar. Hästar spenderar naturligt 60 - 70 % av dygnet till att beta och söka föda, därför är deras mag- och tarmsystem utformat för ett i princip kontinuerligt födointag och magsyran utsöndras med ett jämnt flöde. Om det går mer än 6 timmar mellan utfodringarna har pH-värdet i magsäcken en tendens att sjunka under 4 vilket skadar magslemhinnan. Magsäcken hos häst är uppdelad i två delar, en övre del som är känslig mot magsyra och en nedre del som är van vid det. Trots detta kan magsår förekomma i båda delarna av magsäcken men av olika anledningar. Den vanligaste orsaken till magsår i nedre delen av magsäcken anses främst vara kopplat till stress medan den främsta anledningen till förekomsten i övre delen är kopplat till utfodringen, både utfodringsrutiner och foderstatens uppbyggnad. Kapplöpningshästar, trav- och galopphästar, är den typ av häst där magsår är vanligast förekommande och frekvensen är mellan 80 och 100 % under tävlingssäsongen. Magsår är en sjukdom med diffusa symtom och det finns flera olika anledningar till att det uppkommer och kan även vara i kombination med varandra. Det krävs mer forskning kring ämnet, i synnerhet angående magsår i nedre delen och varför detta uppstår.

Stem cells are endowed with unique qualities: they can both self-renew and give rise to new mature cell types. Central nervous system (CNS) stem cells can give rise to neurons and glia. What factors regulate stem cell fate decisions? Identifying signals that are involved in the regulation of CNS stem cell proliferation, survival, differentiation and migration is fundamental to the understanding of CNS development. In addition, this knowledge hopefully will contribute to more efficient therapies of CNS damages and diseases. The focus of this thesis was to investigate mechanisms of CNS stem cell proliferation and differentiation. We have studied the role for platelet-derived growth factor (PDGF) in these cellular events both in vitro and in vivo. Previous reports have shown that PDGF are implicated in brain tumorigenesis and also supports neuronal differentiation of CNS stem cells. We have found that PDGF promotes survival and proliferation of immature neurons, thereby supporting neuronal differentiation. The intracellular Ras/ERK signaling pathway probably mediates the mitogenic activity of PDGF. In contrast, neuronal differentiation is not dependent on the Ras/ERK pathway. A genetic expression profile of stem cells during their differentiation was obtained. This microarray analysis suggests that PDGF-treated stem cells are at an intermediate stage between proliferation and differentiation. Furthermore, we generated transgenic mice that overexpress Pdgf-b in neural stem cells. Preliminary data indicate no signs of enhanced proliferation of immature neurons. Instead, increased apoptosis was detected in the developing striatum. The results presented in this thesis show how CNS stem cells are regulated by PDGF. PDGFs are widely expressed in the developing CNS and also in some brain tumors, which are thought to arise from CNS stem cells. Thus, this knowledge may contribute to an increased understanding of brain tumorigenesis in addition to normal CNS development.

<p>This thesis combines behavioral observations of African lions (<i>Panthera leo</i>) with genetic analyses, in an attempt to clarify causes and consequences of lion group living. The numerous complex cooperative behaviors of lions present an excellent opportunity to investigate the evolution and maintenance of group living. This thesis focuses on female group living and male dispersal patterns.</p><p>Lion sociality is found to be more complex than previously thought. Short dispersal distances result in strong kinship ties among prides, creating the potential for kin selection to operate among prides. Simultaneously, some prides contained unrelated females, depriving females in such prides of inclusive fitness benefits from group living. Concurrent with short dispersal distances in both males and females, significant genetic differentiation could be detected over relatively short distances in analyses of males. Extensive behavioral observations showed that territorial behaviors were unaffected by kinship ties to intruders. Instead, favorable odds and several environmental conditions were important factors. Space use analyses showed large overlap among prides. Again, kinship did not affect degree of overlap. </p><p>Conclusively, these results show that the ultimate causes of lion sociality remain elusive, but that kin selection may be less important than generally thought. Lion sociality seems to be explicable mainly in terms of direct fitness benefits, which therefore should be given more attention.</p>

<p>This thesis relates modern speciation theory to the effects of sudden changes in the range and size of populations. Special reference is made to the climatic oscillations during the Quaternary ice ages. A meta-analysis of laboratory experiments showed that support for allopatric speciation is weak, especially for the peripatric type of allopatric speciation. Furthermore, factors traditionally believed to increase the likelihood of speciation have had little effect on the generation of reproductive isolation in speciation experiments. However, the method of testing reproductive isolation appeared important, in the sense that experimentally derived sister populations were likely to demonstrate reproductive isolation from each other but not from the unaffected mother population. Raw data from mating tests showed that the poor isolation between mother and daughter populations was an effect of asymmetric mate preferences towards males from the mother population. This suggests that peripatric speciation can be effective in generating reproductive isolation between sister populations. The proposed mechanism is that males become less attractive to females by losing certain secondary sexual traits during population bottlenecks, and that females shift their preferences towards other male traits. Support for this mode of speciation is found in the widespread bird genus <i>Motacilla</i> (wagtails). This genus is characterised by extensive plumage variation and contains a large number of widely distributed taxa in the northern parts of its distribution. This thesis shows that taxonomic diversity of wagtails is inversely related to complexity in song and to diversity in molecular and mitochondrial markers. The northern taxa seem to be descendants of southern populations, which were subjected to bottlenecks during expansions into re-opened habitats after the last ice age. The bottlenecks would not only reduce genetic diversity but also inhibit cultural transmission of song to the leading edge of colonisers, allowing sexual selection on other traits, such as plumage. Rapid plumage differentiation among wagtail taxa appears to be a recurrent process and has lead to convergent evolution, making the currently recognised species <i>Motacilla flava</i> (Yellow Wagtail) polyphyletic.</p>

<p>I developed a precision-cut adrenal slice culture procedure to investigate cytochrome P450 (CYP) catalysed irreversible binding and adrenocorticolytic effects in human, rodent, and fish adrenal tissue, <i>ex vivo</i>. Autoradiography and radioluminography of exposed tissue slices showed that the potent adrenal toxicant 3-methylsulphonyl-2,2´-bis(4-chlorophenyl)-1,1´-dichloroethene (MeSO₂-DDE) causes a selective metabolite binding in <i>zona fasciculata</i> (<i>ZF</i>), which is diminished by the CYP11B1 inhibitor metyrapone. MeSO₂-DDE also reduces corticosterone secretion, increases 11-deoxycorticosterone secretion and causes mitochondrial degeneration in <i>ZF</i> cells in cultured mouse adrenal slices. ACTH treatment of mice induces CYP11B1 and increases irreversible MeSO₂-DDE binding and toxicity in <i>ZF</i> cells. Metyrapone-sensitive binding of MeSO₂-DDE is also observed in human <i>zona fasciculata/reticularis</i> (<i>ZF/ZR</i>) and 11-deoxycorti- sol/corticosterone secretion increases in MeSO₂-DDE-exposed cultured human adrenal slices. The adrenocorticolytic drug 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichlorethane (o,p´- DDD, Mitotane^®) is also bound in <i>ZF/ZR </i>but does not to impair hormone secretion in human adrenal slices at equimolar concentration. A targeted, presumably CYP1B1-catalysed irreversible binding of the adrenocorticolytic carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) in <i>ZF/ZR </i>occurs in rat adrenal slices, whereas presumably CYP1A1-catalysed irreversible binding in endothelial cells is observed in CYP1-induced rats and mice. The rat-specific adrenocorticolytic activity of DMBA may rely on two independent pathological processes resulting in cell death and haemorrhage in the adrenal cortex. In Atlantic cod, selective binding of o,p´-DDD is observed in interrenal cells in cultured anterior kidney slices.</p><p>In conclusion, precision-cut adrenal slice culture is a simple <i>ex vivo</i> test system with which to investigate CYP-catalysed metabolite binding, alteredsteroid hormone secretion and target cell ultrastructure in human, experimental and wild animal tissue. The results imply that organisms under stress could be at increased risk of MeSO₂-DDE induced adrenal toxicity. MeSO₂-DDE is an expected human adrenal toxicant, which should be evaluated as a possible alternative in the therapy of adrenocortical hypersecretion and tumour growth.</p>

<p>In Sweden today, deciduous woodlands are often restricted to small isolated remnants of what it once was. Managing practices have changed concerning both cattle grazing and logging. Thus, dispersal, habitat requirements and their importance for forest species distributions become a relevant issue. Most of the species found in the deciduous flora are perennial herbs. I have examined population dynamics in the forest perennial <i>Sanicula europaea</i>, and its relation to environmental factors such as grazing, competition and spatial and temporal variation in such factors. Moreover I examined species distributions in relation to dispersal and habitat suitability in <i>S. europaea</i> and<i> Dentaria bulbifera</i>. To understand mechanisms behind the observed patterns I performed a number of experiments.</p><p>The results clearly demonstrated that the distribution and abundance of <i>S. europaea</i> was not dispersal limited, whereas the opposite held true for <i>D. bulbifera. Moreover</i>, mollusc exclusion increased recruitment thus influencing population dynamics in <i>D. bulbifera</i>. Leaf losses had negative effects on <i>S. europaea</i> individuals. These negative effects depended both on the extent, frequency and timing of the leaf losses and early losses were more severe than late. Population level effects of grazing were not negative as negative direct effects were counterblanced by positive indirect effects. The positive effects of grazing were mainly in terms of an increased recruitment. </p><p>In<i> S. europaea</i>, high variation in a life cycle transition was always coupled to low elasticity, and traits that varied much due to the examined environmental factors had little importance to population growth rate. A population level perspective is required to assess total effects of environmental factors. In perennial organisms such evaluations need to calculate integrated measures of the effects over the entire life cycle. Field studies spanning several years and demographic models are important to achieve these objectives.</p>

<p>Stem cells are endowed with unique qualities: they can both self-renew and give rise to new mature cell types. Central nervous system (CNS) stem cells can give rise to neurons and glia. What factors regulate stem cell fate decisions? Identifying signals that are involved in the regulation of CNS stem cell proliferation, survival, differentiation and migration is fundamental to the understanding of CNS development. In addition, this knowledge hopefully will contribute to more efficient therapies of CNS damages and diseases.</p><p>The focus of this thesis was to investigate mechanisms of CNS stem cell proliferation and differentiation. We have studied the role for platelet-derived growth factor (PDGF) in these cellular events both <i>in vitro</i> and <i>in vivo</i>. Previous reports have shown that PDGF are implicated in brain tumorigenesis and also supports neuronal differentiation of CNS stem cells. We have found that PDGF promotes survival and proliferation of immature neurons, thereby supporting neuronal differentiation. The intracellular Ras/ERK signaling pathway probably mediates the mitogenic activity of PDGF. In contrast, neuronal differentiation is not dependent on the Ras/ERK pathway. A genetic expression profile of stem cells during their differentiation was obtained. This microarray analysis suggests that PDGF-treated stem cells are at an intermediate stage between proliferation and differentiation. Furthermore, we generated transgenic mice that overexpress <i>Pdgf-b</i> in neural stem cells. Preliminary data indicate no signs of enhanced proliferation of immature neurons. Instead, increased apoptosis was detected in the developing striatum.</p><p>The results presented in this thesis show how CNS stem cells are regulated by PDGF. PDGFs are widely expressed in the developing CNS and also in some brain tumors, which are thought to arise from CNS stem cells. Thus, this knowledge may contribute to an increased understanding of brain tumorigenesis in addition to normal CNS development.</p>

<p>This thesis focuses on the evolutionary interactions between birds and a parasite, the mosquito-borne Sindbis virus (Togaviridae, <i>Alphavirus</i>). In conclusion, the results show that the Sindbis virus is widespread among birds, and that the fitness of infected hosts may be reduced by the virus. Furthermore, viruclearance ability was revealed by male plumage traits, and viraemia was related to hormonal- and social status.</p><p>The distribution of Sindbis virus infections among passerine birds was examined in five areas in Sweden. Almost all species tested were infected, and three species of thrushes weridentified as the main hosts. In a series of experimental infections, greenfinches (<i>Carduelis chloris</i>) kept in aviaries were used ahosts. First, the behavioural consequences of an infection were investigated. During the infection, birds tended to reduce thespontaneous locomotion activity, and when escaping from a simulated predator attack, infected birds had reduced take-off spee Furthermore, when comparing virus clearance rate between male greenfinches, I found that males with large yellow tail ornaments hafaster virus clearance rates as compared to those with smaller ornaments. Thus, male virus clearance ability was honestly revealed by the size of an ornament. Moreover, males with experimentally elevated testosterone levels experienced a delayed, but not increased viraemia as compared to controls. When the relationship between male social ranand viraemia was examined, I found no evidence that high-ranked males suffered reduced rank during the infection. Nevertheless, viraemipatterns of males were related to their social rank, so that low-ranked birds had a delayed viraemia as compared to high-ranked birds. </p>