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Genetics of behavioral evolution in Heliconius butterflies
Get PDFChanges in the way animals perceive and respond to the environment are key to adaptation and speciation. However, we still know little of the genetic mechanisms underlying shifts in behavior. Identifying these genetic changes would provide an important route towards understanding how behavior is generated, both during development and across evolutionary time. To begin to fill this gap, in this thesis I investigate the genetics of behavioral evolution in Heliconius butterflies. In particular, I investigate the genetics of visual mate preferences as well as broader visual adaptations across Heliconius species.
Heliconius butterflies display a striking diversity of warning patterns, which they also use as mating cues to recognize conspecifics. Preferences for conspecific warning patterns have a strong genetic component, but unlike the warning pattern cues, the exact genes responsible remain unknown. In chapter 1, I analyse a causative genomic region for such divergent visual behaviors in two Heliconius species: red H. melpomene and white H. cydno. I couple population genomic and gene expression analyses of neural tissue of these species and their hybrids across development, to identify five genes that are strongly associated with divergent visual preferences. The functions of these candidate genes suggest shifts in behavior involve changes in visual integration or processing, which would allow mate preferences to evolve without altering perception of the wider environment.
In chapter 2, I expand my analyses to include another species: red H. timareta, a co-mimic of H. melpomene. There is substantial evidence that H. timareta acquired its red wing pattern coloration through hybridization (adaptive introgression) with H. melpomene. In this chapter, together with my colleagues, we test the hypothesis that H. timareta also acquired alleles for visual mate preference from H. melpomene. We first show that the same causative region associated with the divergent visual preferences of H. melpomene and H. cydno, also controls visual divergence between H. timareta and H. cydno. I then find genomic signatures of adaptive introgression at the level of candidate behavioral genes identified in chapter 1. One of these candidates, regucalcin1, also shows patterns of gene expression strongly linked to visual preference across Heliconius species and their hybrids. Overall, I find evidence that visual preference alleles have crossed species barriers to facilitate adaptive shifts in behavior in Heliconius.
Finally, chapter 3 goes beyond divergence in mate preferences to investigate broad-scale neural divergence associated with speciation in the H. melpomene/H. cydno group. Species within this group are separated across an ecological gradient of open to closed forest. We find evidence that species have adapted to this ecological transition at the neural level, through heritable, volumetric expansion of visual processing regions of the brain. We find that these same visual structures show intermediate morphologies in F1 hybrids, which likely disrupt their behavioural function. I then show that these brain volumetric changes are mirrored by adaptive divergence in gene expression level in the neural tissue of these species. Finally, I find evidence for selection against the introgression of alleles (with distinct neural expression level) between species, further indicating that neural divergence contributes to reproductive isolation. Overall, we show that broad-scale sensory/neural adaptations to the visual environment, at both morphological and gene expression level, contribute substantially to behavioral isolation and speciation across Heliconius
Typisierung der Enteroviren aus Entero-/Rhinoviren-positiven Surveillance-Proben aus dem Erregermonitoring Bayern Influenza Sentinel (EMBIS)
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Vergleich zweier interstitieller Radiofrequenztherapien (Fine RFITT und Pure RFITT) bei Hyperplasie der unteren Nasenmuscheln
Get PDFDie interstitielle thermische Radiofrequenztherapie (RFITT) stellt eine etablierte und komplikationsarme Therapie der Hyperplasie der unteren Nasenmuschel dar. Es stehen unterschiedliche Modulationsmuster der Radiofrequenztherapie zur Verfügung.
Ziel der vorliegenden Arbeit war es mittels prospektiver, doppelt verblindeter und randomisierter Studie im intraindividuellen matched pairs Design den etablierten Pure-RFITT-Modus mit dem neuen Fine-RFITT-Modus zu vergleichen.
Methoden: Es wurden 20 Patienten mit Nasenmuschelhyperplasie und Nasenatmungsbehinderung eingeschlossen. Eine der beiden unteren Nasenmuscheln wurde mittels Fine Modus behandelt, die andere mittels Pure Modus. Somit fungierte jeder Patient als seine eigene Kontrollgruppe. Die Zuteilung der Modi zu der entsprechenden Nasenmuschel erfolgte dabei randomisiert. Präoperativ, am dritten postoperativen Tag sowie zwei und sechs Wochen danach erfolgten Kontrolluntersuchungen. Objektive Messparameter waren die Schwellung der unteren Nasenmuschel, die Krustenbildung und die Nasensekretion, die durch einen verblindeten Untersucher erfasst wurden. Subjektive Bewertungen durch die Patienten erfolgte mittels visueller Analogskala und betrafen die Häufigkeit Nasenatmungsbehinderung, den Schweregrad Nasenatmungsbehinderung, den Juckreiz, die Krustenbildung, die Nasensekretion, das Schmerzempfinden sowie das Behandlungsempfinden während der Prozedur.
Ergebnis: Es konnte gezeigt werden, dass der neue Fine-RFITT-Modus dem Pure-RFITT-Modus bezüglich des Behandlungsempfindens überlegen ist. Keine relevanten Unterschiede zeigten sich bezüglich des Operationsergebnisses der beiden Modi, gemessen an Nasenschwellung, Nasensekretion und Krustenbildung. Ebenfalls ergaben sich keine Unterschiede bezüglich des Schmerzempfindens, des Juckreizes sowie der Komplikationsraten und dem Ausmaß der Intervention
Etablierung zweier muriner Tumorzelllinien (mit PD-L1 knock-out bzw. Ovalbumin-Überexpression) zur weiteren Evaluierung des Mechanismus von PD-1-CD28-Fusionsrezeptor-transduzierten T-Zellen in vitro und in vivo
Get PDFRobust visual feedforward and feedback signal processing in the mouse thalamus
Get PDFRobust vision starts in the retina and is finally accomplished in the cortex – but what role does the dorsolateral geniculate nucleus of the thalamus (dLGN) play at the intermediate stage of the early visual processing pathway?
In this thesis, I investigated how the dLGN in the awake mouse computes visual representations and how dLGN activity is shaped by retinal feedforward signals, cortico-thalamic feedback and behavioural state. A guiding hypothesis was that the dLGN is not a passive relay of retinal inputs, but an active signal transformer that may improve the reliability, efficiency, and robustness of the neural population code.
In the first study included in this work, we investigated which functional retinal ganglion cell (RGC) types project to the dLGN and how multiple RGC types converge onto single dLGN relay cells. The second study explored the impact of global suppression of V1 cortico-thalamic feedback on dLGN responses to naturalistic stimuli, and compared the effects of feedback versus locomotion and natural versus artificial stimuli. Lastly, in the third study, we modelled dLGN activity to more complex movie stimuli and used a more selective optogenetic feedback suppression method and assessed if and how the model benefits from ad- ditional information about feedback, as well as locomotion and pupil size.
To summarize our results, we first found that the majority of functional RGCs project to the dLGN, which displays a large response diversity, and that an average of five types converge onto a given relay cell, two of which exert the strongest functional impact. Secondly, global feedback suppression reduced dLGN firing rates and increased bursting, with stronger effects observed for naturalistic stimuli than artificial ones, and similar but independent effects of feedback versus locomotion. Lastly, the third study confirmed that dLGN mean firing rates are decreased by direct feedback suppression, and increased during periods of running and large pupil sizes. These observations are reflected in the model, whose predictions benefit mostly from additional feedback but not behavioural state information, but which nevertheless manages to extract dLGN spatio-temporal receptive fields (STRFs) for complex movies as well as artificial stimuli.
In conclusion, in vivo mouse dLGN activity is shaped mostly by the influences of sparse functional retino-thalamic convergence, and is modulated to a lesser degree by cortico-thalamic feedback and behavioural state. This suggests that the dLGN is not a passive relay but instead actively transforms visual signals by combining its visual and extra-visual inputs, in agreement with the consensus view on the subject
Verbesserung der vorklinischen Ausbildung durch computerunterstützte Auswertung der Zahnaufstellung in Teilprothesen
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The massless limit of massive gauge theories
Get PDFWir untersuchen massive, nicht-lineare Eichtheorien mit von Handeingefügtem Massenterm. Zunächst betrachten wir die massive Yang-Mills-Theorie, die Theorie eines nicht-abelschen Vektorfeldes. Die konventionelle Herangehensweise suggeriert, dass der Grenzfall verschwindender Massen für diese Theorie nicht kontinuierlich ist. Um weitere Einblicke in diese Theorie zu erhalten, betrachten wir darüber hinaus das einfachere Modell einer Proca-Theorie mit kubischer Selbstwechselwirkung und zeigen, dass diese Theorie unter einer perturbativen Unstetigkeit im Grenzfall verschwindender Massen leidet. Wir bestätigen, dass dies in beiden Theorien auf die longitudinale Moden zurückgeführt werden kann, d.h. auf Freiheitsgrade, die in den masselosen Theorien abwesend sind. Wir zeigen, dass diese Moden allerdings durch nicht-lineare Terme jenseits der Vainshtein-Skala stark koppeln und damit von den übrigen Freiheitsgraden, bis auf kleine Korrekturen, entkoppeln. Daher finden wir, dass der Grenzfall verschwindender Massen der massiven Yang-Mills-Theorie kontinuierlich ist, wir von A. I. Vainshtein und I. B. Khriplovich vermutet.
Wir erweitern dann unsere Untersuchung auf die Kalb-Ramond-Theorie, d.h. die Theorie einer massiven, antisymmetrischen Zweiform, sowie die Theorie einer massiven Dreiform. Wir vergleichen die beiden Theorien mit der Proca-Theorie sowie der Theorie eines massiven Skalarfelds, wobei wir alle vier durch eine Selbstwechselwirkung modifizieren. Wir finden, dass alle Theorien, abgesehen von der des massiven Skalarfelds, die selbe Vainshtein-Skala haben. Die Freiheitsgrade der beiden Paare von Theorien verhalten sich jedoch unterschiedlich. In der Proca-Theorie geht die longitudinale Mode in ein stark gekoppeltes Regime über und entkoppelt von den transversalen Moden, welche weiterhin schwach gekoppelt sind und im Grenzfall verschwindender Masse überleben. In der Kalb-Ramond-Theorie koppeln die transversalen Moden stark und entkoppeln von der transversalen Mode, welche weiterhin schwach koppelt und daher im Grenzfall verschwindender Masse überlebt. Auf ähnliche Weise zeigen wir, dass das Pseudoskalar, der Freiheitsgrad der massiven Dreiform, stark koppelt. Hieraus folgt, dass diese Theorie im Granzfall verschwindender Massen keine dynamischen Freiheitsgrade enthält. Diese Ergebnisse deuten auf einen Widerspruch mit zahlreichen Behauptungen in der Literatur, dass die Theorien eines massiven Kalb-Ramond-Feldes und des Proca-Feldes sowie einer massiven Dreiform und eines reellen Skalarfelds jeweils dual zueinander sind.We study massive non-linear gauge theories with mass added by hand. First, we consider the massive Yang-Mills theory, the theory of a non-Abelian vector field. The conventional approaches suggest that this theory does not have a smooth massless limit. To gain further insight into this theory, we also consider a toy model of Proca theory with a cubic self-interaction and show that this theory also suffers from perturbative discontinuity. We confirm that in both theories this is due to the longitudinal modes, degrees of freedom that are absent in the massless theories. Nevertheless, we show that due to the non-linear terms, these modes become strongly coupled at the Vainshtein scale which coincides with that of unitarity violation. Beyond it, they remain strongly coupled and decouple from the remaining degrees of freedom up to small corrections. Thus, we find that the massless limit of the massive Yang-Mills theory is smooth, as conjectured by A. I. Vainshtein and I. B. Khriplovich.
We then extend our study to the theory of a massive antisymmetric two-form -- the Kalb-Ramond theory -- and a theory of a massive three-form. We compare the two theories with Proca theory and a theory of a massive scalar field respectively, modifying them by a quartic self-interaction. We find that all theories apart from the massive scalar theory have the same Vainshtein scale. However, the degrees of freedom of the two pairs of theories do not behave the same. In Proca theory, the longitudinal mode enters a strong coupling regime and decouples from the transverse modes which remain weakly coupled and survive in the massless limit. In contrast, in Kalb-Ramond theory, the transverse modes become strongly coupled and decouple from the longitudinal mode that is in the weak coupling regime and survives in the massless limit. Similarly, we show that the pseudoscalar -- the degree of freedom of a massive three-form -- becomes strongly coupled. Thus in the massless limit, this theory has no propagating degrees of freedom. These results indicate a contradiction with numerous claims in the literature, that the theories of massive Kalb-Ramond and Proca field, and theories of massive three form and a scalar field are dual