590 Tiere (Zoologie)
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Das Gezeter des Seggenrohrsängers, die Alarmrufe der Uferschnepfe, das Gemecker der Bekassine, das Geschnarre des Wachtelkönigs und die Pfiffe des Tüpfelsumpfhuhns - kaum ein anderer Lebensraum weist so viele exklusive Vogelarten auf wie die Flusstalmoore. Dieser Moortyp dominiert die Grundmoränenlandschaft des südlichen Ostseeraumes. Jedoch wurde auch kein anderer Lebensraum vom Menschen so gründlich in seiner ökologischen Funktionstüchtigkeit gestört. Insbesondere die grossflächigen und tief gehenden Entwässerungen des 20. Jahrhunderts führten zum Verstummen zahlreicher Vogelarten. So ist etwa der Seggenrohrsänger heute vom globalen Aussterben bedroht. In Nordostdeutschland wurden in den letzten 15 Jahren grosse Anstrengungen unternommen, die Ökosystemleistungen der Flusstalmoore neu zu beleben. Dazu wurden über 20 000 Hektar Moorfläche wiedervernässt. Wie reagiert die Vogelwelt auf diese neuen Veränderungen? Bestehen Chancen für eine Wiederansiedlung verschollener Vogelarten? Wie können die Wiedervernässungsmassnahmen gestaltet werden, um gefährdete Vogelarten zu begünstigen? Lässt sich das Leitbild des Artenschutzes mit den Leitbildern des Moor- und Klimaschutzes und zukünftigen Bewirtschaftungsformen vereinen? Diesen Fragen ist der Autor in einer umfassenden Studie von Vogelwelt, Vegetation und Hydrologie am Beispiel des Peene- und Trebeltals in Mecklenburg-Vorpommern nachgegangen und stellt seine Ergebnisse hier vor.
Having been regarded as wastelands until quite recently, wetlands are increasingly acknowledged as ecosystems of high biodiversity. Wetland restoration projects are often accompanied by the implementation of specific species management programs. Naturally, for effective management measures, profound knowledge of the target speciesʼ ecological requirements is obligatory, including habitat selection, feeding ecology as well as spatial behaviour such as movements within and between patches of suitable habitat. Yet, big knowledge gaps exist for many marshland birds which is particularly true for highly secretive species such as rails and crakes. Considered as the least known among the Palaearctic breeding birds, most information about the Baillon's Crake Zapornia pusilla is only anecdotic, resulting in strong uncertainties with regard to the species' distribution, population sizes, status, migratory behaviour as well as ecological requirements. This can be mainly attributed to the species' skulking behaviour and its seemingly highly erratic occurrence. Baillon's Crakes in the Western Palaearctic and Palaeotropics are referred to as the subspecies Z. p. intermedia. While European breeding birds are assumed to winter in sub-Saharan wetlands, African populations are considered rather to be itinerant with local movements induced by seasonal or anthropogenic habitat changes. However, for both migratory movements, major directions or routes are unknown. The discovery of a large number of Baillon's Crakes presumably wintering in the floodplains of the Parc National des Oiseaux du Djoudj (PNOD), situated in the Senegal River Delta, WAfrica, initiated this thesis. The main aim of the study was, firstly, to clarify the status and size of this population and assess its connectivity to European breeding population(s). Secondly, in order to improve the knowledge about the species' ecological requirements as a basis for the National Parks conservation management, habitat selection, spatial behaviour as well as dietary selectivity were investigated. The major part of the fieldwork was performed in PNOD in the course of the dry season during periods of 1.5 - 2.5 months from December - March 2009, 2010 and 2013. Baillon's Crakes were mainly caught with cage traps, ringed and common measurements were taken, including moult status. Skin tissue as well as one rectrice was sampled for DNA and stable isotope analyses. This was also done for Baillon's Crakes caught in European breeding grounds in Germany, Montenegro and Southern Spain. For dietary analyses, faecal samples were collected in PNOD in winter 2009/2010. Furthermore, some individuals were equipped with radio-transmitters to determine home range size and habitat selection. For the identification of the most relevant habitat parameters both on a population as well as on the individuals' level, we used a vegetation map based on satellite imagery covering the entire Djoudj area as well as maps generated on the basis of aerial photographs taken at two study sites.
In holometabolic insects, senescence starts at sexual maturation and condition diminishes with age. Young virgin males should gain the highest mating success. Although sperm quality and quantity typically decreases with age, older males have been shown to have a higher mating success in a variety of insect taxa. Life-history theory predicts an increased aggressive and persistent courtship behaviour, due to a decrease of the residual reproductive value and thus, the opportunity for future reproduction. In the butterfly Bicyclus anynana, older males gain up to a 4x higher mating success despite a poorer condition, compared to younger males. As older males were found to court more often and for longer time bouts,suggesting a higher intrinsic motivation, there is evidence for the residual reproductive value hypothesis. On the other hand, an age-specific variation of male sex pheromones may provide females with information, being helpful to chose specific males. The latter could be males which have proven a high fitness in terms of survival, thus essentially reflecting a “good genes" hypothesis. This doctoral thesis investigated the reasons underlying old male mating advantage in B. anynana. The first study tested whether old male mating advantage prevails, even if females were unable to distinguish between older and younger males. The results were backed up by examining female rejection rates, male courtship frequency, courtship duration, time to copulation and mating duration. Older males had a significantly higher mating success compared to younger ones regardless of differences in pheromone blends or the females ability to smell. Older males courted more often and longer. The results support the residual reproductive value hypothesis. Study 2 investigated post-copulatory sexual selection in B. anynana. Females were double-mated, allowing for sperm competition and cryptic mate choice. Older males had a higher paternity success than younger ones, when the former were the last mating partner. The paternity success was balanced across age classes when older males were the first mating partner. Older males transferred larger spermatophores with higher numbers of eupyrene sperm than younger males. B. anynana does not exhibit cryptic mate choice and last-male precedence is the most probable fertilization pattern. The higher proportion of offspring sired by older males is due to significantly increased numbers of fertile sperm compared to younger males. The latter are clearly disadvantaged, as the higher sperm numbers provided by older males counteract the benefits of last-male precedence. Study 3 explored determinants of mating success in B. anynana. Successful males had longer wings, a heavier thorax, a lighter abdomen, a higher fat content, and higher phenoloxidase expression levels. Mating success seemed to be directly linked to proxies of flight performance. Successful males showed a better flight performance, in turn increasing mating success. As energy reserves are of crucial importance for flight manoeuvres, they may play a significant role in male mating success. Study 4 tested the effects of male age and mating number on spermatophore mass, sperm number, male oxidative status, and reproductive success by manipulating age and mating frequency in male B. anynana. Spermatophore mass and sperm numbers increased significantly with age, while antioxidant defences and oxidative damage declined. Female fecundity and egg-hatching success was highest when being mated with young virgin males. Antioxidant defences decreased with age, being a possible reason for the negatively affected reproductive success in females. Ejaculate quality diminished with age and mating number, despite larger spermatophores and higher sperm numbers being found in older males. Therefore, spermatophore size and sperm numbers can not be considered as reliable proxies of male condition. The final study proofed whether male sex pheromone comprise honest signals and which traits might be associated with increased pheromone titres. Pheromone titres were analysed among successful and unsuccessful males when being mated with either a control or a scent-blocked female. Both groups did not differ in pheromone levels. Successful males had significantly higher numbers of eupyrene sperm. No correlation between male pheromones and any investigated trait was found, suggesting that pheromone titres do not provide reliable information on male quality. Nothing indicates that male sex pheromones in B. anynana play a decisive role in female mate choice. Successful males generally have a better body condition, resulting in a more vigorous courtship behaviour and higher sperm numbers. Hence, variation in body condition rather than pheromone titres is more likely to determine male mating success. Mating decisions are primarily driven by male behaviour. The results suggest that old male mating advantage arises from sexual conflict.
Dwarf spiders (Linyphiidae, Erigoninae) are especially suitable for sexual selection research as many of them exhibit sexual dimorphism, with males possessing modified prosomata. In those species that have been investigated in detail the modified structures are equipped with a glandular tissue that produces secretions, which the females contact and take up during courtship/copulation. The time of secretion release, and refilling of the reservoirs was analysed on an ultrastructural level in male Oedothorax retusus. The results suggest that the main function of the secretions is gustatorial courtship and not the emission of volatile pheromones for mate attraction. Mating decisions and reproductive success are influenced by secondary sexual traits that evolved under sexual selection. However, an individual´s nutritional status is also important for mate choice. Since spiders are regularly exposed to limited prey availability, adult feeding status can be considered an important component of spider mating behaviour. In order to test for the effects of dietary restriction, females of the closely related species O. retusus and O. apicatus were subject to a short period of food shortage. The effects of low- (LD) vs. high-diet (HD) treatment on courtship, mating probability and behaviour, and reproduction were analysed. We found that short phases of diet restriction as adults have a high impact on copulation and reproduction in the two dwarf spider species. Whenever females mate with more than one male, and sperm is stored prior to fertilization, males may suffer from sperm competition. Mating plugs that block the female genital openings after mating are a male strategy to avoid sperm competition. Although mating plugs occur in many species, their function and origin has hardly been investigated. O. retusus males transfer amorphous material onto the female genitalia during mating. We investigated the location of plug production using x-ray microtomography (μCT) as well as light and transmission electron microscopy (TEM). Furthermore, we asked whether males are limited in the production of the amorphous plug material in successive matings. The plug material is produced in a gland inside the male pedipalp and stored close to the blind end of the sperm storage compartment. The size of the first plug a male produced significantly influenced the size of subsequent plugs. Obviously, males do not possess unlimited amounts of plug material in a certain period, which may severely limit their ability to secure paternity through subsequent mating plugs. Even though mating plugs seem to be an obvious means to secure paternity, their potential in securing paternity depends on their mechanical efficacy and persistence. Consequently, the influence of the size of the plug material (mating duration as a proxy) and the age of the mating plug (time interval between successive copulations) on its efficacy was investigated. Small and fresh plugs were least effective, whereas large plugs were highly effective. We were able to show that mating plugs in O. retusus are a powerful mechanical safeguard whose efficacy varies with plug size and age. Genitalia in animals with internal fertilization are complex, species-specific, and underlie rapid evolution. In spiders, male and female genitalia are paired, and have to interact during mating, which results in an even higher complexity. Pedipalps (transformed pair of legs) in male spiders are used as secondary sperm transfer organs that are not directly connected to the gonads. Due to the high complexity of male pedipalps, it has been taken for granted that pedipalps are side specific and cannot be used flexibly into either female copulatory opening. We investigated potential flexible pedipalp use in O. retusus. Our findings demonstrate a flexible insertion mode in a dwarf spider with complex pedipalps but relatively simple female genitalia. Our findings corroborate sexual selection as the selective regime for the evolution of complex and diverse genitalia. The results of this thesis show how complex sexual selection acts in the dwarf spiders O. retusus and O. apicatus. It shapes the evolution of male and female genitalia, affects mate choice (pre- and postcopulatory), mating behaviour, and influences mating success and reproduction. All these factors and traits affect an individual´s evolutionary fitness, and their interactions help to understand how sexual selection acts.
The impact of inbreeding under different environmental conditions and of artificial selection on cold tolerance was investigated in laboratory populations of the tropical butterfly Bicyclus anynana. The investigation focused on (1) the effects of inbreeding on several fitness-related traits and whether inbred individuals are more susceptible to stress, (2) interactions between inbreeding, genetic adaptation to cold stress and environmental conditions, (3) the effects of artificial selection and inbreeding in the adult stage in other developmental stages, and (4) the effect of inbreeding depression on the heat shock response. Environmental conditions are not constant over time; consequently organisms have to deal with environmental changes. Besides naturally fluctuating conditions, human-induced climate change may increase temperature changes as well as the severity of heat or cold waves. Temperature-stress resistance describes an organism’s ability to cope with stressful temperatures. Enhanced resistance to temperature stress can be reached by phenotypic plasticity or genetic adaptation. Plastic organisms are able to react fast to changing environmental conditions, whereas genetic adaptation is more important for long-term adaptation. Natural habitats may also be affected by human impact, causing habitat loss or fragmentation and changes in population structure. A decrease in the population size may result in inbreeding and inbreeding depression (ID). Consequences of inbreeding are well documented, and inbred individuals are predicted to be more sensitive to environmental stress than outbred individuals. The long term persistence of species and populations depends on their ability to adapt to novel conditions which in turn depends on genetic diversity. Therefore, studies of temperature resistance and its evolution in relation to inbreeding are very important. First a higher susceptibility of inbred individuals to environmental stress was determined in different populations of B. anynana. Inbreeding depression was revealed for several fitness-related traits, but not for immunity traits or heat tolerance. Temperature affected most traits, revealing the importance of temperature on ectotherms; just two hours of thermal stress affected important reproductive, life-history and immunity traits already. Importantly though, no evidence were found that inbred individuals are more susceptible to stressful temperatures than outbred individuals. Genetic adaptation and phenotypic plasticity can interact with one another, resulting in genotype-environmental interactions (G x E). The hypotheses tested here were that some genotypes are more plastic than others and that lines with increased cold stress resistance are less plastic with regard to cold resistance than control lines. To induce plastic responses the exposed lines differed in cold tolerance and inbreeding to different temperatures as well as different feeding regimes and measured fitness-related traits. Several interactions were detected in which a selection regime was involved, but these interactions did not show a clear overall pattern. In summary though, findings were that marginal impacts of directional selection and inbreeding on plastic responses and suggest that, at least for my study organism, the genetic architecture of fitness-related traits is not connected with the architecture of plastic responses. The next investigation concerned with the manifestation of genetic adaptation to produce one specific phenotype across development stages and possible trade-offs. The assumption tested was that there is a genetic link between different developmental stages to produce one definite phenotype by imposing selection in the adult stage only. Lines selected for increased cold resistance in the adult stage were used and increased cold resistance throughout all developmental stages was expected. However, higher cold resistance was found only in the adult stage and not in developmental stages. This could be either the result of a resource allocation trade-off between different stages or that there is no cold resistance phenotype. Thus, if selection takes place in the adult stage it does not affect the others. In the last experiment investigation was directed to determine whether there are negative inbreeding effects on the heat shock protein (HSP) response. Under stressful conditions, organisms produce the HSPs and they act as chaperons required for refolding and repairing of stress degraded proteins. Testing was oriented to find if inbreeding as a genetic stressor´ provokes a higher HSP expression and if there is evidence for higher temperature stress susceptibility on inbred individuals. Findings indeed showed a stronger HSP up-regulation in control compared to inbred lines with a negative inbreeding impact occurrence, which may causally underlie inbreeding depression.
Herzinsuffizienz ist eine der häufigsten Ursachen für Morbidität und Mortalität weltweit. Zum jetzigen Zeitpunkt ist die Herztransplantation im fortgeschrittenen Stadium der Erkrankung der einzige kurative Therapieansatz. Durch den Einsatz von Stammzellen als Therapieoption der Herzinsuffizienz konnten in den letzten Jahren im Rahmen von tierexperimentellen und klinischen Studien zahlreiche vielversprechende Daten gewonnen werden. Ziel der Stammzelltransplantationen ist es, das geschädigte Gewebe zu ersetzen, die Gefäßneubildung zu induzieren und somit die kardiale Funktion aufrechtzuerhalten. Kardialen Stammzellen wird durch die Fähigkeit der Selbsterneuerung, Proliferation und der Differenzierung in spezialisierte Zelltypen ein großes Regenerationspotential zugeschrieben. Weiterhin wurde ein positiver Einfluss von kardialen Stammzellen auf die Gefäßneubildung mittels parakriner Effekte beschrieben. Obwohl durch die Transplantation von kardialen Stammzellen eine Regeneration des geschädigten Gewebes, z.B. nach einem Myokardinfarkt, beobachtet wurde, ist noch wenig über die genauen Wirkungsweisen der eingesetzten Stammzellen bekannt. Zudem bleibt unklar, welchen Einfluss eine Schädigung des Herzens auf die Stammzellen und ihre Funktion hat und welche Faktoren dabei eine Rolle spielen. Die Existenz von residenten kardialen Stammzellen konnte sowohl im tierischen als auch im humanen Herzen nachgewiesen werden. Jedoch ist bis heute nicht geklärt, warum der Pool an residenten kardialen Progenitorzellen nicht merklich zur Regeneration nach einer Schädigung beitragen kann. Die vorliegende Arbeit befasste sich daher mit der Untersuchung der Funktion muriner residenter kardialer Progenitorzellen, die positiv für das Stammzellantigen-1 (Sca-1) sind, unter physiologischen und pathophysiologischen Bedingungen. Hierfür wurde der Einfluss des Renin-Angiotensin-Aldosteron Systems (RAAS), welches entscheidend an der Entwicklung einer Herzinsuffizienz beteiligt ist, auf die Funktion Sca-1 positiver Zellen in vitro untersucht. Anschließend wurde der Einfluss pathophysiologischer Aldosteronkonzentrationen, wie sie im Rahmen einer Herzinsuffizienz nachweisbar sind, auf die sekretorische Aktivität der Sca-1 positiven Zellen bestimmt. Im Rahmen dieser Arbeit konnte erstmals gezeigt werden, dass die Komponenten des RAAS die Migrationsrate Sca-1 positiver Zellen dosis- und zeitabhängig beeinflussen, wobei vor allem pathophysiologische Konzentrationen von Aldosteron eine signifikante Steigerung der Migrationsrate der Sca-1 positiven Zellen bewirkten. Des Weiteren konnte eine Mineralokortikoidrezeptor-vermittelte Wirkungsweise des Aldosterons auf die Funktion der Sca-1 positiven Zellen festgestellt werden, welche durch den Einsatz der Aldosteron-Antagonisten Spironolakton und Eplerenon inhibiert wurde. Anhand der an Sca-1 positiven Zellen durchgeführten Sekretomanalysen konnte gezeigt werden, dass sich die sekretorische Aktivität kardialer Progenitorzellen unter physiologischen und pathophysiologischen Bedingungen unterscheidet. Pathophysiologische Stimuli führen zu einer erhöhten sekretorischen Aktivität kardialer Progenitorzellen. Die Analyse der sekretierten löslichen Faktoren deutet auf eine Beteiligung Sca-1 positiver Zellen an Reparatur- und Regenerationsprozessen mittels parakriner Mechanismen nach einer Schädigung hin. Die vorliegenden Ergebnisse zeigen, dass mit dem Mineralokortikoid Aldosteron ein Faktor identifiziert wurde, welcher zur Optimierung der Stammzelltherapie, z.B. im Rahmen einer Herzinsuffizienz, dienen kann. Weiterhin konnte in dieser Arbeit das Verhalten und die Funktion kardialer Progenitorzellen unter pathophysiologischen Bedingungen näher charakterisiert werden und mögliche Mechanismen aufgezeigt werden, über welche kardiale Stammzellen an Regenerationsprozessen beteiligt sein können.
Sowohl für die Leistungsausprägung als auch die Gesundheit landwirtschaftlicher Nutztiere ist die relative Verteilung von Skelettmuskel- und Fettgewebe ein entscheidender Faktor. Entwicklungs- und Wachstumsprozesse werden neben gewebespezifischen Faktoren auch durch Wechselwirkungen zwischen beiden Geweben beeinflusst. Beim Menschen sind das Auftreten von Adipositas und die damit verbundene geringere Ausprägung der Muskulatur und Veränderung metabolischer Prozesse entscheidende Risikofaktoren für die Entwicklung von Krankheiten. Die Aufklärung der Regulation der Entwicklung von Muskel- und Fettgewebe ist daher ein wichtiges Anliegen der Nutztierforschung, aber auch der humanmedizinischen Forschung. Adiponectin und Leptin gehören zu den am besten untersuchten Adipokinen, wobei der Fokus hauptsächlich auf der Regulation der Fettsäureoxidation, des Glucosestoffwechsels und der Insulinsensitivität lag und liegt. Beide Faktoren können sowohl von Fett- als auch Skelettmuskelgewebe synthetisiert und sezerniert werden und somit physiologische Prozesse in beiden Geweben beeinflussen. In wenigen Studien, hauptsächlich durchgeführt am Muskel von Nagern, wurden unterschiedliche Ergebnisse gezeigt, die auf widersprüchliche Effekte (positiv, negativ oder nicht nachweisbar) der Adipokine auf das Muskelwachstum hinweisen. Die Wirkung beider Adipokine auf den Proteinstoffwechsel porciner Muskelzellen wurde bisher noch nicht beschrieben. Ebenso gibt es bislang keinen Nachweis für das Vorhandensein der spezifischen Rezeptorproteine für Adiponectin (ADIPOR1, ADIPOR2) und Leptin (LEPR) im Skelettmuskel des Schweins. Das Ziel der Untersuchungen dieser Arbeit bestand in der Erforschung zellulärer und molekularer Prozesse der Regulation des Wachstums porciner Skelettmuskelzellen durch Adiponectin und Leptin. Es sollten erstmals 1) die direkte Wirkung beider Adipokine auf das Wachstum und die Differenzierung porciner Skelettmuskelzellkulturen und 2) die zugrundeliegenden Regulationsmechanismen unter Beteiligung wichtiger Signalwege des Energie- und Proteinstoffwechsels beschrieben werden. Aufgrund der Genexpression der spezifischen Rezeptoren für Adiponectin kann der porcine Skelettmuskel als Adiponectin-sensitives Gewebe betrachtet werden. Bei den Untersuchungen zeigte sich, dass die Wirkungen von Adiponectin und Leptin auf proliferierende porcine Skelettmuskelzellen von den vorherrschenden Kulturbedingungen abhängig sind. Die Behandlung mit Adiponectin bei der Verwendung von serumfreiem aber Wachstumsfaktor-supplementiertem Medium resultierte in einer verminderten DNA-Syntheserate, welche auf Wechselwirkungen zwischen dem Adipokin und dem im Medium vorhandenen Wachstumsfaktor bFGF zurückzuführen war. Für Leptin konnte unter diesen Bedingungen nur eine kurzzeitige Hemmung der Proliferation porciner Muskelzellen beobachtet werden. Des Weiteren wurde die Wirkung von Adiponectin, aber nicht Leptin, auf die Prolfiferation porciner Myoblasten durch Ölsäure moduliert. Weiterhin zeigte sich, dass die Vitalität adipokinbehandelter Zellen im Vergleich zu unbehandelten Kontrollzellen unter serumfreien, wachstumsfaktor-supplementierten Bedingungen leicht verbessert war. Unter Niedrigserumbedingungen führten beide Adipokine zu einer gesteigerten DNA-Syntheserate, welche bei Leptin mit einer Verminderung der Zellzahl einherging. Im Gegensatz zu serumfreien Kulturbedingungen, unter denen die vorhandenen Wachstumsfaktoren die Zellen offensichtlich vor einem negativen Einfluss der Adipokine schützen, wurde bei der Verwendung von Medium mit niedrigem Serumgehalt eine verminderte Zellvitalität adipokinbehandelter Zellen beobachtet. Ein Einfluss von Adiponectin und Leptin auf den Proteinstoffwechsel differenzierender Kulturen konnte unter den verwendeten Kulturbedingungen nicht gezeigt werden. Weiterhin erhöhten Adiponectin und Leptin zwar den Differenzierungsgrad porciner Myoblasten in Form eines erhöhten Fusionsgrades, aber nicht bezüglich der Aktivität des Markerenzyms Creatinkinase. Die Untersuchungen verschiedener intrazellulärer Schlüsselsignalmoleküle zeigen erste Hinweise auf eine Beteiligung des p44/42 MAPK Signalweges an der Vermittlung der Adipokineffekte, obwohl dessen Aktivierung möglicherweise zu kurz ist, um eine langfristige stimulierende Wirkung auf downstream targets und somit auf physiologische Prozesse zu haben. Die Ergebnisse dieser Arbeit leisten zum einen einen wichtigen Beitrag zur Aufklärung der Regulation von Wachstums- und Entwicklungsprozessen des Muskel- und Fettgewebes durch wechselseitige Beeinflussung. Zum anderen sind die beim Schwein gewonnenen Erkenntnisse aufgrund der dem Menschen ähnlichen Physiologie durchaus auf die Humanforschung übertragbar und somit ebenfalls für die Erforschung adipositas-assoziierter Erkrankungen beim Menschen relevant.
Chaetognaths are a fascinating taxon with unique features and a great impact on marine food webs as primary predators of zooplankton. Their phylogenetic position has been subject to many speculations ever since their discovery and even contemporary phylogenomic methods have not yet been able to suggest a stable hypothesis on their phylogenetic position within the Bilateria. Neuroanatomical studies may contribute new aspects to this discussion. This study aims to provide new insights into the chaetognath nervous system using a fresh set of methods to determine characters for a phylogenetic discussion. The method of choice in this case was immunohistochemistry combined with confocal microscopy. Experiments were conducted with a host of antibodies. The most effective target antigenes were RFamides (a family of neuropeptides), synapsins (synaptic proteins), tyrosinated tubulin (a cytoskeletal element, especially in neurites) and BrdU (bromodeoxyuridin, a proliferation marker). Each of those markers was of great use in highlighting certain aspects of the nervous system. A fresh look at the development of juvenile chaetognaths shortly after hatching revealed that the ventral nerve center (VNC) is developing earlier than the brain and that the production of neurotransmitters has already started at hatching. Specifically, some neurons exhibit RFmide-like immunoreactivity (ir). Neurogenesis continues for about five days after hatching and the mode of division in the neuronal stemcells is asymmetrical. In adult chaetognaths, the brain is divided into a stomatogastric anterior and a sensory posterior neuropil domain. It contains a set of individually identifiable neurons that exhibit RFamide-like ir. The study highlights the interspecific variation of brain architecture between representatives of spadellids and sagittids. The VNC consists of two lateral bands of somata that flank a central neuropil. Within the VNC exists a serial arrangement of neurons with RFamide-like ir. A variety of other neurotransmitters and related substances are also present in both, the brain and the VNC. More interspecific differences and similarities were explored in another part of the study, comparing even more different chaetognath species and focusing on the VNC and its internal structure. The two species of Krohnitta have an unusual distribution of nuclei that is not clearly separated into two lateral bands like in other species. Many of the sagittid species exhibit a striation pattern of the neuropil that is mostly absent in other groups and some of their nerve nets show varying degrees of order as opposed to the rather disorganized nerve net in other groups. In addition, immunohistochemical methods were applied to several specimens of Gnathostomula sp. in order to test one of the many hypotheses about the chaetognaths phylogenetic position, a sister-group relationship to gnathostomulids. A comparison between the two taxa, taking into account also other gnathifera and platyhelminthes, makes a sistergroup relationship between chaetognaths and gnathostomulids very unlikely. In conclusion, chaetognaths remain in an enigmatic phylogenetic position and likely branched off close to the deuterostome/protostome split.
The goal of this thesis was to study the systematic relationships within the superfamily Sylvioidea (Aves: Passeriformes) in general and within the closely related families Acrocephalidae and Locustellidae in particular, by means of DNA sequences. Sylvioidea itself and families therein were the focus of many studies based as well on morphological characters as on DNA. Due to their morphological similarity and their presumably rapid radiation most studies failed to solve relationships between sylvioidean families and also demarcations of single families and relations within are still in progress. In this study, an enlargement of previous datasets, both taxa and number of DNA sequences, and more sophisticated analysis methods were used to improve the resolution in Sylvioidea, Acrocephalidae and Locustellidae. In addition, the applicability of barcoding in Acrocephalidae was tested. The monophyly of Sylvioidea could be supported and the families Paridae and Remizidae, which were sometimes still included, clustered among the outgroup taxa. Four families, Nicatoridae, Panuridae, Alaudidae, and Macrosphenidae constitute basal splits within Sylvioidea. The division of the former sylviid/timaliid clade in five families, Sylviidae, Leiothrichidae, Pellorneidae, Timaliidae, and Zosteropidae was supported. Scotocerca, Erythrocercus, and Hylia, previously supposed to be members of Cettiidae, were shown not to belong to this family. As the three genera are also morphologically and ecologically different, they were here proposed to be elevated to family rank, Scotocercidae, Erythrocercidae and Hyliidae, respectively. The family Acrocephalidae consisted of the four genera, Nesillas, Acrocephalus, Hippolais, and Chloropeta. In the analysis for this thesis, the latter three appeared to be non-monophyletic. One Acrocephalus species, A. aedon was sister to a clade containing four species of Hippolais as well as two out of three Chloropeta species. They were all merged in the genus Iduna, based on the DNA evidence and shared morphological and ecological characters. Iduna had priority over Hippolais or Chloropeta according to the International Code of Zoological Nomenclature. The one remaining Chloropeta species (C. gracilirostris) had to be renamed to Calamonastides as Chloropeta was no longer available for this taxon. Seven genera were included in the re-analysis of the family Locustellidae: Locustella, Bradypterus, Megalurus, Dromaeocercus, Schoenicola, Cincloramphus, and Eremiornis. Apart from the monotypic genera Dromaeocercus and Eremiornis and Schoenicola, of which only one species was included, the remaining genera were found to be non-monophyletic. One clade contained all Locustella species, Megalurus pryeri and all Asian/Oriental Bradypterus species. All species in this clade were synonymized with Locustella, as the type species of Locustella was included, whereas the type species of Bradypterus fell in a different clade. Therefore, the remaining African Bradypterus species retained their genus name, and Dromaeocercus was renamed to Bradypterus as it clustered within Bradypterus. Cincloramphus, intermingling with the remaining Megalurus species, was synonymized with the latter. Barcoding, growing in popularity for delimiting species, was tested in its applicability for Acrocephalidae. Fourteen taxa currently recognized as full species would fall under the 2% threshold of sequence divergence proposed for delimiting species using the mitochondrial cytochrome b gene. It was also shown that it is important to clarify which part of a DNA sequence is used, as different parts can give different results regarding the 2% threshold. In addition, the choice of “complete deletion” or “pairwise deletion” in calculating genetic distances is important, if incomplete are sequences used.
Die „protein misfolding cyclic amplification“ (PMCA) ist eine Methode zur Amplifikation des pathologischen Prion-Proteins in vitro und ermöglicht so den hochsensitiven Nachweis von PrPSc-Molekülen. Ziel der vorliegenden Arbeit war es, diese neue Untersuchungsmethode zum Nachweis des BSE-Erregers zu adaptieren, verschiedene Erregerstämme zu charakterisieren und unterschiedliche Gewebeproben aus der Pathogenese-Studie des FLI (HOFFMANN et al. 2007) auf ihren Priongehalt zu testen. Durch Festlegung von Standardwerten für die Ultraschallbehandlungen im Hinblick auf Zyklenzahl, Schallstärke, Inkubationstemperatur und Zyklusdauer sowie Verwendung definierter negativer als auch positiver Kontrollen, konnte die PMCA erfolgreich angepasst werden. Verwendet wurde als Substrat Hirnhomogenat transgener Mäuse, die das bovine PrPC überexpremieren (Tgbov XV). Bei Untersuchungen von Gewebeproben von insgesamt 4 Rindern aus der Pathogenesestudie konnte PrPSc in folgenden Gewebetypen nachgewiesen werden: dem dorsalen Root-Ganglion, dem Ganglion coeliacum, dem Ganglion stellatum, dem Ganglion trigeminale, der caudalen Medulla, den jejunalen und ilealen Peyer´schen Platten, dem Kolon, dem ilealen und jejunalen mesenterialen Lymphknoten, dem Nervus opticus, den Nebennieren, dem Rectum und dem Rückenmark und erstmals auch im Labmagen, dem Oesophagus und dem Pansen. Die PMCA wurde ebenso für die Untersuchung zur Speziesbarriere eingesetzt. Dazu wurden verschiedene TSE-Stämme (klassische BSE, atypische BSE, klassische Scrapie, ovine und caprine BSE sowie CWD) in unterschiedlichen Substraten mit bovinem und ovinem PrPC amplifiziert. Die Ergebnisse zeigen, dass die Speziesbarriere eine verringerte Amplifikationseffizienz in vitro verursachte und teilweise die Amplifikation vollständig inhibierte. Zusätzlich wurde beobachtet, dass die Amplifikationseffizienz nicht nur von der Sequenzhomologie bestimmt wird, sondern auch von der Konformation der eingesetzten Isolate. Dies korreliert mit der erleichterten Infizierbarkeit von Individuen gleicher Art im Gegensatz zu der verringerten Übertragbarkeit zwischen artfremden Spezies (Speziesbarriere). Die mangelnde Umfaltungs-Effizienz ist eine Folge von Spezies-spezifischen Sequenzunterschieden im Prion-Protein und daraus resultierender Strukturunterschiede. Einen Hinweis auf ein verändertes Verhalten der Seeds in vivo und in vitro wurde bereits in der Literatur beschrieben. Intrazerebral infizierte Hamster, die mit einem in der PMCA amplifizierten Seed inokuliert wurden bewiesen, dass das neu gebildete PrPres infektiös war, da sich bei den Tieren nach etwa 165 Tagen, post infektionem, klinische Symptome für eine Scrapieerkrankung zeigten (CASTILLA et al. 2005). Wurden die Hamster aber direkt mit einem Hamster-Scrapie-Stamm der Variante 263K inokuliert, erkrankten diese schon nach 60 Tagen (KIMBERLIN et al. 1977), was auf eine Veränderung der PrPres-Fragmente während der PMCA-Reaktion hindeutet. Eine vergleichbare Studie zeigte, dass sich diese Ergebnisse bei intrazerebraler Inokulation in Mäusen reproduzieren lassen (WEBER et al. 2007). In der PMCA konnten also PrPres-Amplifikate mit veränderten biochemischen Eigenschaften generiert werden. Zukünftige Arbeiten müssen zeigen, inwieweit die PMCA andere diagnostische Nachweisverfahren (Mausbioassay, Immunhistochemie) für den BSE-Erreger ergänzen oder gar ersetzen kann. Um die PMCA als ein sicheres Diagnoseverfahren zu verwenden, sind jedoch weitere Untersuchungen insbesondere hinsichtlich der Spezifität der Methode nötig.