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The range expansion of the Southern Small White butterfly, Pieris mannii : underlying ecological and evolutionary mechanisms
Get PDFSpecies range margins are highly dynamic, changing as a result of complex eco-evolutionary processes. Determining both the abiotic and biotic drivers and the species-specific traits underlying successful range expansions will be vital for predicting future distribution patterns, especially in the current era of anthropogenic environmental change. In pursuit of this knowledge, I used the rapid range expansion of the Mediterranean butterfly species Pieris mannii (MAYER, 1851) into Central Europe as a case study. Specifically, I was interested in studying the relative importance of niche tracking versus niche evolution and the contributions of genetic trait changes and (evolved) phenotypic plasticity within the context of niche evolution. Towards this end, I adopted a multi-methodological approach, including correlative species distribution models (to test for the role of niche tracking in response to climate change; Chapter 1) and common garden experiments. With the latter, I tested for niche evolution in host plant use behaviour, thermal tolerance and life-history traits by comparing replicated populations from P. mannii’s historical and newly established range (Chapter 2). I additionally used the tropical butterfly species Bicyclus anynana (Butler, 1879) to assess how reproductive behaviour is affected by the interaction of temperature and host plant quality, both prone to variations across the range of herbivorous insects (Chapter 3). The results from species distribution modelling revealed that niche tracking, driven by climate change, can be largely ruled out as the primary driver of P. mannii’s range expansion. There was, however, evidence for rapid niche evolution in various phenotypic and life history traits, including female host plant use behaviour. Females from the expanding populations showed increased flexibility in their acceptance and preference for different host plant species, potentially increasing the availability of favourable habitats as connecting “stepping stones” in space and time. The experiments with B. anynana yielded, moreover, interesting insights into temperature-dependent variations in reproductive output on different host plants (reduced fecundity on low-quality host plants under stressfully high-temperature conditions) and a potential trade-off between high selectivity and fecundity. The question of whether these patterns are prevalent in range-expanding species in natural settings warrants further in-depth examinations. Despite shifts in host use behaviour, expanding populations of P. mannii exhibited an enhanced cold tolerance, a trait considered essential for terrestrial ectotherms undergoing successful poleward range expansions in temperate regions. Heat tolerance, however, showed no significant variation across populations, which might indicate a relaxation of selection pressure on upper thermal tolerance limits at higher latitudes. Compared to populations of the ancestral distribution, individuals from range edge populations also exhibited an increased fecundity, frequently characterised as a key trait underlying successful range expansions. As mechanisms underlying trait changes, I identified both (increased and decreased) phenotypic plasticity, demonstrated by increased cold tolerance and accelerated larval development (in individuals of the expanding populations, developing under cool temperature conditions; Genotype x Environment interaction), and genetic trait changes, underlying shifts in host preference and fecundity in reproducing females of range edge populations. With the results of the present thesis, I demonstrate that successful range expansions can be driven by rapid niche evolution in multiple traits, which are associated with abiotic and biotic environmental characteristics. Thus, I highlight the importance of eco-evolutionary dynamics underlying the expression of species-specific "Expansive Phenotypes". Several open questions are discussed and the need for further research, especially concerning potential trade-offs and costs associated with trait expression during range expansion, is underlined
From the outer space to the inner cell: deconvoluting the complexity of Bacillus subtilis disulfide stress responses by redox state and absolute abundance quantification of extracellular, membrane, and cytosolic proteins
Get PDFUnderstanding cellular mechanisms of stress management relies on omics data as a valuable resource. However, the lack of absolute quantitative data on protein abundances remains a significant limitation, particularly when comparing protein abundances across different cell compartments. In this study, we aimed to gain deeper insights into the proteomic responses of the Gram-positive model bacterium Bacillus subtilis to disulfide stress. We determined proteome-wide absolute abundances, focusing on different sub-cellular locations (cytosol and membrane) as well as the extracellular medium, and combined these data with redox state determination. To quantify secreted proteins in the culture medium, we developed a simple and straightforward protocol for the absolute quantification of extracellular proteins in bacteria. We concentrated extracellular proteins, which are highly diluted in the medium, using StrataClean beads along with a set of standard proteins to determine the extent of the concentration step. The resulting data set provides new insights into protein abundances in different sub-cellular compartments and the extracellular medium, along with a comprehensive proteome-wide redox state determination. Our study offers a quantitative understanding of disulfide stress management, protein production, and secretion in B. subtilis
Reliabilität der Messungen von Knochenabbau an Miniimplantaten zur Stabilisierung von Teilprothesen mittels Panoramaschichtaufnahmen
Get PDFZiel der Studie: Unter Verwendung digitaler Panoramaschichtaufnahmen (PSA) zeigt diese
Arbeit die Intra- und Interrater Reproduzierbarkeit von Messungen des vertikalen
Knochenniveaus an Miniimplantaten nach vorangegangener Längenkalibrierung.
Material und Methoden: Insgesamt wurden 50 digitale PSA zufällig aus einer prospektiven
klinischen Studie, in der strategische Miniimplantate zur Stabilisierung von herausnehmbaren
Teilprothesen untersucht wurden, ausgewählt. Die vertikalen Knochenniveaumessungen an
152 Miniimplantaten wurden von drei geschulten Untersuchern (ein Untersucher zweimal)
digital ausgewertet. Wenn es Messunterschiede von ≥ 0,5 mm Differenz zwischen den
Studienuntersuchern gab, wurde erneut gemessen. Der Intraklassen-Korrelationskoeffizient
(ICC) wurde zur Schätzung der Zuverlässigkeit verwendet. Angelehnt an die klinisch
bedeutsame Änderung von 0,2 mm, wurden für die Übereinstimmung der Standardmessfehler
(SEM) und die kleinste nachweisbare Änderung (SDC) herangezogen.
Ergebnisse: Der Mittelwert des vertikalen Vergrößerungsfaktors, der anhand der gemessenen
Miniimplantatlänge in der PSA durch die tatsächliche Implantatlänge dividiert wurde, liegt
zwischen 1,19 – 1,23 und hatte je eine ausgezeichnete ICC von > 0,9. Die SEM der Intra-
(0,0063 mm) und Interrater Statistik (0,0062 mm) sind gering, sowie die errechnete SDC von
0,0175 mm (Intra-) und 0,0171 mm (Interrater). Bei den vertikalen Knochenniveaumessungen
sind im Interrater Vergleich ICC – Werte von > 0,8 bereits nach der ersten Messrunde erzielt
worden. Insgesamt sind 28 Messstellen (9 %) in den PSA nicht befundbar gewesen und bei
97 Messpunkten (32 %) war die Differenz zwischen den Untersuchern über 0,5 mm. Nach einer
Schulung und kritischen Begutachtung durch den Studienleiter wurden weitere 8 Messstellen
ausgeschlossen. Letztlich lag die Differenz der vertikalen Knochenniveaumessunterschiede
aller Untersucher zueinander in der letzten Auswertungsrunde unter 0,5 mm. Der SEM in der
Intrarater Statistik konnte von ursprünglich 0,26 mm auf 0,11 mm und der, der Interrater
Statistik von 0,55 mm auf 0,12 mm verbessert werden. Die SDC mit einer 95 %igen
Glaubwürdigkeit verbesserte sich in der Intrarater Statistik von 0,73 mm auf 0,31 mm und in
der Interrater Statistik von 1,52 mm auf 0,34 mm. Bei einer Glaubwürdigkeit von 50 % für
diese spezielle Betrachtung betrugen sowohl die Intra- als auch die Interrater SDCs 0,11 mm.
Schlussfolgerung: Die digitalen Panoramaschichtaufnahmen können zuverlässig zur
Bestimmung des vertikalen Knochenniveaus an Miniimplantate eingesetzt werden, wenn zuvor
eine Längenkalibrierung erfolgt, es mindestens zwei geschulte Untersucher gibt, ein vorheriger
Ausschluss nicht quantifizierbarer Messstellen stattfindet und gegenseitige Kalibrierungssitzungen
durchgeführt werden
Metabolic remodeling in cardiac hypertrophy and heart failure with reduced ejection fraction occurs independent of transcription factor EB in mice
Get PDFBackground: A metabolic shift from fatty acid (FAO) to glucose oxidation (GO) occurs during cardiac hypertrophy (LVH) and heart failure with reduced ejection fraction (HFrEF), which is mediated by PGC-1α and PPARα. While the transcription factor EB (TFEB) regulates the expression of both PPARGC1A/PGC-1α and PPARA/PPARα, its contribution to metabolic remodeling is uncertain.
Methods: Luciferase assays were performed to verify that TFEB regulates PPARGC1A expression. Cardiomyocyte-specific Tfeb knockout (cKO) and wildtype (WT) male mice were subjected to 27G transverse aortic constriction or sham surgery for 21 and 56 days, respectively, to induce LVH and HFrEF. Echocardiographic, morphological, and histological analyses were performed. Changes in markers of cardiac stress and remodeling, metabolic shift and oxidative phosphorylation were investigated by Western blot analyses, mass spectrometry, qRT-PCR, and citrate synthase and complex II activity measurements.
Results: Luciferase assays revealed that TFEB increases PPARGC1A/PGC-1α expression, which was inhibited by class IIa histone deacetylases and derepressed by protein kinase D. At baseline, cKO mice exhibited a reduced cardiac function, elevated stress markers and a decrease in FAO and GO gene expression compared to WT mice. LVH resulted in increased cardiac remodeling and a decreased expression of FAO and GO genes, but a comparable decline in cardiac function in cKO compared to WT mice. In HFrEF, cKO mice showed an improved cardiac function, lower heart weights, smaller myocytes and a reduction in cardiac remodeling compared to WT mice. Proteomic analysis revealed a comparable decrease in FAO- and increase in GO-related proteins in both genotypes. A significant reduction in mitochondrial quality control genes and a decreased citrate synthase and complex II activities was observed in hearts of WT but not cKO HFrEF mice.
Conclusions: TFEB affects the baseline expression of metabolic and mitochondrial quality control genes in the heart, but has only minor effects on the metabolic shift in LVH and HFrEF in mice. Deletion of TFEB plays a protective role in HFrEF but does not affect the course of LVH. Further studies are needed to elucidate if TFEB affects the metabolic flux in stressed cardiomyocytes
Optimierte Bildgebung der Multiplen Sklerose Einfluß von Spulen- und Sequenztechnologien
Get PDFDer Nachweis von demyelinisierenden Läsionen in T2-gewichteten Aufnahmen ist entsprechend der aktuellen Empfehlungen entscheidender diagnostischer Bestandteil für den Nachweis der örtlichen und zeitlichen Dissemination der Erkrankung Multiple Sklerose in der MRT. Hierfür sind ein möglichst optimales SNR und CNR der demyelinisierenden Läsionen in T2-gewichteten Aufnahmen notwendig. Die SPACE-Sequenz stellt im Bereich der Hochfeld-MRT eine alternative Sequenztechnologie dar, welche die SAR-Limitationen der etablierten TSE-Sequenzen umgeht. Ziel der Studie war es, zu zeigen, dass die Darstellung demyelinisierender Läsionen in T2-gewichteten Aufnahmen bei Patienten mit Multipler Sklerose durch die SPACE-Sequenz und die 32-Kanal-Spule sowohl hinsichtlich der objektiven wie auch der subjektiven Bildqualität in der MRT optimiert werden kann. Die statistische Auswertung mittels Wilcoxon Rangsummentest ergab einen signifikanten Zugewinn an SNR und CNR (p< 0,001) sowohl für die Space Sequenz gegenüber der TSE Sequenz unabhängig mit welcher Spulenkombination als auch für die 32-Kanalspule gegenüber der 12-Kanalspule, unabhängig von der Sequenzwahl sowie einen signifikanten Mehrgewinn für die Kombination aus Space-Sequenz und 32-Kanal-Spule. Die qualitative Bewertung durch zwei erfahrene Neuroradiologen und einen MS-kundigen Neurologen auf einer 4-Punkte Skala ergab eine signifikant verbesserte Bildqualität für die 32- Kanal-Spule unabhängig von der Sequenz und keinen signifikanten Unterschied zwischen den Sequenzen Space und TS. In Kombination mit einer 32-Kanal-Kopfspule ermöglicht die SPACE-Sequenz eine Verbesserung der subjektiven Bildqualität sowie von SNR und CNR der demyelinisierenden Läsionen bei Patienten mit Multipler Sklerose
Quantitative analysis of trabecular bone tissue cryosections via a fully automated neural network-based approach
Get PDFCryosectioning is known as a common and well-established histological method, due to its easy accessibility, speed, and cost efficiency. However, the creation of bone cryosections is especially difficult. In this study, a cryosectioning protocol for trabecular bone that offers a relatively cheap and undemanding alternative to paraffin or resin embedded sectioning was developed. Sections are stainable with common histological dying methods while maintaining sufficient quality to answer a variety of scientific questions. Furthermore, this study introduces an automated protocol for analysing such sections, enabling users to rapidly access a wide range of different stainings. Therefore, an automated ‘QuPath’ neural network-based image analysis protocol for histochemical analysis of trabecular bone samples was established, and compared to other automated approaches as well as manual analysis regarding scattering, quality, and reliability. This highly automated protocol can handle enormous amounts of image data with no significant differences in its results when compared with a manual method. Even though this method was applied specifically for bone tissue, it works for a wide variety of different tissues and scientific questions
Marine particle microbiomes during a spring diatom bloom contain active sulfate-reducing bacteria
Get PDFPhytoplankton blooms fuel marine food webs with labile dissolved carbon and also lead to the formation of particulate organic matter composed of living and dead algal cells. These particles contribute to carbon sequestration and are sites of intense algal-bacterial interactions, providing diverse niches for microbes to thrive. We analyzed 16S and 18S ribosomal RNA gene amplicon sequences obtained from 51 time points and metaproteomes from 3 time points during a spring phytoplankton bloom in a shallow location (6-10 m depth) in the North Sea. Particulate fractions larger than 10 µm diameter were collected at near daily intervals between early March and late May in 2018. Network analysis identified two major modules representing bacteria co-occurring with diatoms and with dinoflagellates, respectively. The diatom network module included known sulfate-reducing Desulfobacterota as well as potentially sulfur-oxidizing Ectothiorhodospiraceae. Metaproteome analyses confirmed presence of key enzymes involved in dissimilatory sulfate reduction, a process known to occur in sinking particles at greater depths and in sediments. Our results indicate the presence of sufficiently anoxic niches in the particle fraction of an active phytoplankton bloom to sustain sulfate reduction, and an important role of benthic-pelagic coupling for microbiomes in shallow environments. Our findings may have implications for the understanding of algal-bacterial interactions and carbon export during blooms in shallow-water coastal areas
Investigating the neural mechanisms of transcranial direct current stimulation effects on human cognition: current issues and potential solutions
Get PDFTranscranial direct current stimulation (tDCS) has been studied extensively for its potential to enhance human cognitive functions in healthy individuals and to treat cognitive impairment in various clinical populations. However, little is known about how tDCS modulates the neural networks supporting cognition and the complex interplay with mediating factors that may explain the frequently observed variability of stimulation effects within and between studies. Moreover, research in this field has been characterized by substantial methodological variability, frequent lack of rigorous experimental control and small sample sizes, thereby limiting the generalizability of findings and translational potential of tDCS. The present manuscript aims to delineate how these important issues can be addressed within a neuroimaging context, to reveal the neural underpinnings, predictors and mediators of tDCS-induced behavioral modulation. We will focus on functional magnetic resonance imaging (fMRI), because it allows the investigation of tDCS effects with excellent spatial precision and sufficient temporal resolution across the entire brain. Moreover, high resolution structural imaging data can be acquired for precise localization of stimulation effects, verification of electrode positions on the scalp and realistic current modeling based on individual head and brain anatomy. However, the general principles outlined in this review will also be applicable to other imaging modalities. Following an introduction to the overall state-of-the-art in this field, we will discuss in more detail the underlying causes of variability in previous tDCS studies. Moreover, we will elaborate on design considerations for tDCS-fMRI studies, optimization of tDCS and imaging protocols and how to assure high-level experimental control. Two additional sections address the pressing need for more systematic investigation of tDCS effects across the healthy human lifespan and implications for tDCS studies in age-associated disease, and potential benefits of establishing large-scale, multidisciplinary consortia for more coordinated tDCS research in the future. We hope that this review will contribute to more coordinated, methodologically sound, transparent and reproducible research in this field. Ultimately, our aim is to facilitate a better understanding of the underlying mechanisms by which tDCS modulates human cognitive functions and more effective and individually tailored translational and clinical applications of this technique in the future
Translation of Multidimensional Health Locus of Control Scales, Form C in Patients with Headache
Get PDFThe MHLC-C is a condition-specific instrument measuring the internal and external loci of control beliefs, adaptable to various health conditions. Translated into Swedish and Chinese, this study aims to translate the MHLC-C into German using the FACID-Method. The English version is validated and reliable; the German version requires these validation steps
Cardiac remodelling in non‐alcoholic fatty liver disease in the general population
Get PDFBackground and Aims
Non‐alcoholic fatty liver disease (NAFLD) is associated with increased risk for cardiovascular disease. Our study investigates the contribution of NAFLD to changes in cardiac structure and function in a general population.
Methods
One thousand ninety‐six adults (49.3% female) from the Study of Health in Pomerania underwent magnetic resonance imaging including cardiac and liver imaging. The presence of NAFLD by proton density fat fraction was related to left cardiac structure and function. Results were adjusted for clinical confounders using multivariable linear regression model.
Results
The prevalence for NAFLD was 35.9%. In adjusted multivariable linear regression models, NAFLD was positively associated with higher left ventricular mass index (β = 0.95; 95% confidence interval (CI): 0.45; 1.45), left ventricular concentricity (β = 0.043; 95% CI: 0.031; 0.056), left ventricular end‐diastolic wall thickness (β = 0.29; 95% CI: 0.20; 0.38), left atrial end‐diastolic volume index (β = 0.67; 95% CI: 0.01; 1.32) and inversely associated with left ventricular end‐diastolic volume index (β = −0.78; 95% CI: −1.51; −0.05). When stratified by sex, we only found significant positive associations of NAFLD with left ventricular mass index, left atrial end‐diastolic volume index, left ventricular cardiac output and an inverse association with global longitudinal strain in women. In contrast, men had an inverse association with left ventricular end‐diastolic volume index and left ventricular stroke volume. Higher liver fat content was stronger associated with higher left ventricular mass index, left ventricular concentricity and left ventricular end‐diastolic wall thickness.
Conclusion
NAFLD is associated with cardiac remodelling in the general population showing sex specific patterns in cardiac structure and function