@phdthesis{Gabel2024, author = {Gabel, Martin Sebastian}, title = {Behavioural resistance to \(Varroa\) \(destructor\) in the Western honeybee \(Apis\) \(mellifera\) - Mechanisms leading to decreased mite reproduction}, doi = {10.25972/OPUS-36053}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-360536}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {The Western Honeybee (Apis mellifera) is among the most versatile species in the world. Its adaptability is rooted in thousands of the differently specialized individuals acting jointly together. Thus, bees that are able to handle a certain task or condition well can back up other individuals less capable to do so on the colony level. Vice versa, the latter individuals might perform better in other situations. This evolutionary recipe for success ensures the survival of colonies despite challenging habitat conditions. In this context, the ectoparasitic mite Varroa destructor reflects the most pronounced biotic challenge to honeybees worldwide. Without proper treatment, infested colonies rapidly dwindle and ultimately die. Nevertheless, resistance behaviours against this parasite have evolved in some populations through natural selection, enabling colonies to survive untreated. In this, different behaviours appear to be adapted to the respective habitat conditions and may complement each other. Yet, the why and how of this behavioural response to the mite remains largely unknown. My thesis focuses on the biological background of Varroa-resistance traits in honeybees and presents important findings for the comprehension of this complex host-parasite interaction. Based on this, I draw implications for both, applied bee breeding and scientific investigations in the field of Varroa-resistance. Specifically, I focus on two traits commonly found in resistant and, to a lower degree, also mite-susceptible colonies: decreased mite reproduction and the uncapping and subsequent recapping of sealed brood cells. Examining failures in the reproductive success of mites as a primary mechanism of Varroa-resistance, I was able to link them to specific bee behaviours and external factors. Since mite reproduction and the brood rearing of bees are inevitably connected, I first investigated the effects of brood interruption on the reproductive success of mites. Brood interruption decreased the reproductive success of mites both immediately and in the long term. By examining the causes of reproductive failure, I could show that this was mainly due to an increased share of infertile mites. Furthermore, I proved that interruption in brood rearing significantly increased the expression of recapping behaviour. These findings consequently showed a dynamic modulation of mite reproduction and recapping, as well as a direct effect of brood interruption on both traits. To further elucidate the plasticity in the expression of both traits, I studied mite reproduction, recapping behaviour and infestation levels over the course of three years. The resulting extensive dataset unveiled a significant seasonal variation in mite reproduction and recapping. In addition, I show that recapping decreases the reproductive success of mites by increasing delayed developing female offspring and cells lacking male offspring. By establishing a novel picture-based brood investigation method, I could furthermore show that both the removal of brood cells and recapping activity specifically target brood ages in which mite offspring would be expected. Recapping, however, did not cause infertility of mites. Considering the findings of my first study, this points towards complementary mechanisms. This underlines the importance of increased recapping behaviour and decreased mite reproduction as resistance traits, while at the same time emphasising the challenges of reliable data acquisition. To pave the way for a practical application of these findings in breeding, we then investigated the heritability (i.e., the share of genotypic variation on the observed phenotypic variation) of the accounted traits. By elaborating comparable test protocols and compiling data from over 4,000 colonies, we could, for the first time, demonstrate that recapping of infested cells and decreased reproductive success of mites are heritable (and thus selectable) traits in managed honeybee populations. My thesis proves the importance of recapping and decreased mite reproduction as resistance traits and therefore valuable goals for breeding efforts. In this regard, I shed light on the underlying mechanisms of both traits, and present clear evidence for their interaction and heritability.}, subject = {Varroa destructor}, language = {en} } @article{Freitag‐WolfMunzJungeetal.2021, author = {Freitag-Wolf, Sandra and Munz, Matthias and Junge, Olaf and Graetz, Christian and Jockel-Schneider, Yvonne and Staufenbiel, Ingmar and Bruckmann, Corinna and Lieb, Wolfgang and Franke, Andre and Loos, Bruno G. and Jepsen, S{\o}ren and Dommisch, Henrik and Schaefer, Arne S.}, title = {Sex-specific genetic factors affect the risk of early-onset periodontitis in Europeans}, series = {Journal of Clinical Periodontology}, volume = {48}, journal = {Journal of Clinical Periodontology}, number = {11}, doi = {10.1111/jcpe.13538}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262445}, pages = {1404 -- 1413}, year = {2021}, abstract = {Aims Various studies have reported that young European women are more likely to develop early-onset periodontitis compared to men. A potential explanation for the observed variations in sex and age of disease onset is the natural genetic variation within the autosomal genomes. We hypothesized that genotype-by-sex (G × S) interactions contribute to the increased prevalence and severity. Materials and methods Using the case-only design, we tested for differences in genetic effects between men and women in 896 North-West European early-onset cases, using imputed genotypes from the OmniExpress genotyping array. Population-representative 6823 controls were used to verify that the interacting variables G and S were uncorrelated in the general population. Results In total, 20 loci indicated G × S associations (P < 0.0005), 3 of which were previously suggested as risk genes for periodontitis (ABLIM2, CDH13, and NELL1). We also found independent G × S interactions of the related gene paralogs MACROD1/FLRT1 (chr11) and MACROD2/FLRT3 (chr20). G × S-associated SNPs at CPEB4, CDH13, MACROD1, and MECOM were genome-wide-associated with heel bone mineral density (CPEB4, MECOM), waist-to-hip ratio (CPEB4, MACROD1), and blood pressure (CPEB4, CDH13). Conclusions Our results indicate that natural genetic variation affects the different heritability of periodontitis among sexes and suggest genes that contribute to inter-sex phenotypic variation in early-onset periodontitis.}, language = {en} } @article{FrankeFaraoneAshersonetal.2012, author = {Franke, B. and Faraone, S. V. and Asherson, P. and Buitelaar, J. and Bau, C. H. D. and Ramos-Quiroga, J. A. and Mick, E. and Grevet, E. H. and Johansson, S. and Haavik, J. and Lesch, K.-P. and Cormand, B. and Reif, A.}, title = {The genetics of attention deficit/hyperactivity disorder in adults, a review}, series = {Molecular Psychiatry}, volume = {17}, journal = {Molecular Psychiatry}, doi = {10.1038/mp.2011.138}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124677}, pages = {960-987}, year = {2012}, abstract = {The adult form of attention deficit/hyperactivity disorder (aADHD) has a prevalence of up to 5\% and is the most severe long-term outcome of this common neurodevelopmental disorder. Family studies in clinical samples suggest an increased familial liability for aADHD compared with childhood ADHD (cADHD), whereas twin studies based on self-rated symptoms in adult population samples show moderate heritability estimates of 30-40\%. However, using multiple sources of information, the heritability of clinically diagnosed aADHD and cADHD is very similar. Results of candidate gene as well as genome-wide molecular genetic studies in aADHD samples implicate some of the same genes involved in ADHD in children, although in some cases different alleles and different genes may be responsible for adult versus childhood ADHD. Linkage studies have been successful in identifying loci for aADHD and led to the identification of LPHN3 and CDH13 as novel genes associated with ADHD across the lifespan. In addition, studies of rare genetic variants have identified probable causative mutations for aADHD. Use of endophenotypes based on neuropsychology and neuroimaging, as well as next-generation genome analysis and improved statistical and bioinformatic analysis methods hold the promise of identifying additional genetic variants involved in disease etiology. Large, international collaborations have paved the way for well-powered studies. Progress in identifying aADHD risk genes may provide us with tools for the prediction of disease progression in the clinic and better treatment, and ultimately may help to prevent persistence of ADHD into adulthood.}, language = {en} }