Biology subjects

Buellesbach, J.

Publications and source records attributed to Buellesbach, J..

6 recordsLinked to original sources

bioRxiv2025

Genomic architecture of species-specific sex pheromone variation and mate choice

Speciation often begins with subtle changes in sexual communication and mate choice, yet the genetic basis of these early reproductive barriers remains largely unresolved. Here, we dissect the chemical and genomic architecture underlying species-specific female cuticular sex pheromones and their role in mate choice in two closely related parasitoid wasp species. Using high-resolution quantitative trait locus (QTL) mapping, fine-scale chemical profiling, and behavioral assays on hybrid populations, we identify three methyl-branched alkanes as key pheromonal compounds that strongly predict male mating preferences. QTL explaining their species-specific variation partially co-localize with genomic regions enriched for candidate genes involved in cuticular hydrocarbon biosynthesis, including cytochrome P450 enzymes and fatty acid synthases. These findings suggest a potential mechanistic link between the variation in these gene clusters and species-specific chemical signaling. Further comparative analyses reveal hitherto unrecognized sex-specific regulatory effects, cytoplasmic influences, and complex genomic interactions shaping the variation in these pheromonal profiles. This study is among the first to connect individual pheromone compounds with mate choice and their underlying genomic basis in a haplodiploid system, offering a rare glimpse into how chemical divergence can reinforce behavioral isolation and potentially drive early speciation.

evolutionary biology↗

bioRxiv2025

The impact of a fatty acid synthase gene in regulating a complex multifunctional trait essential for survival and sexual communication

The genetic basis of multi-functional traits shaped by both natural and sexual selection remains poorly understood. In insects, cuticular hydrocarbons (CHCs) are an excellent example of such traits, providing protection against different micro-climatic conditions while simultaneously encoding cues predominantly used in sexual signaling. The fatty acid synthase (fas) gene family has been implied as an important cornerstone in initiating and maintaining CHC functionality, whereas their exact biosynthetic and regulatory mechanisms have remained poorly understood. Here, we characterize a single fatty acid synthase gene (fas3) impacting the main CHC functions in the parasitoid wasp model organism Nasonia vitripennis. Knockdown of fas3 significantly decreases wasp survival under desiccation stress while also completely depleting sexual attractiveness of female wasps, where this trait naturally functions as sex pheromone. Transcriptomic analyses revealed that fas3 regulates other fas and CHC-associated genes, as well as key biosynthetic pathway hubs. We also identified striking sex-specific expression differences in fas3 across individual developmental stages, suggesting divergent functional roles of this gene in males and females. These findings largely advance our knowledge on the multi-functionality of fas genes in governing survival and sexual signaling and underscore their relevance for future studies on metabolomics, ecological adaptation, and sexual communication. Author SummaryTraits that serve both adaptive and reproductive functions--such as those involved in survival and mating success--are often complex, and their genetic foundations remain poorly understood. In insects, chemical compounds on the outer cuticle represent a prime example: they help prevent desiccation and act as key sexual signals. In this study, we investigate the gene fas3, a member of the fatty acid synthase family, in the parasitoid wasp Nasonia vitripennis, whose knockdown drastically reduces these surface chemicals. Consequently, both of their natural functionalities, namely enhancement of survival in dry conditions and female sexual attractiveness, are severely impaired. Transcriptomic analysis further revealed that fas3 also regulates multiple other genes, including those in further major biosynthetic pathways. Our findings shed light on how a single gene can coordinate the expression of multifunctional traits, contributing to both ecological adaptation and sexual communication.

genetics↗

bioRxiv2025

Identification of pseudotetraivprolide from Pseudomonas entomophila give novel insights into the biosynthesis of detoxin/rimosamide-like anti-antibiotics

Novel variants of known natural product (NP) classes might guide our understanding of biosynthesis, mode of action and potential application as drugs for all members of such NP classes. Here we describe a novel member of the widespread detoxine/rimosamide-like (DRL) natural products named pseudotetraivprolide from Pseudomonas strains, which has the characteristic DRL-activity of protecting Bacillus cereus against the antibiotic blasticidin S. The generation of several deletion and complemented mutants, heterologous expression experiments, identification and structure elucidation of several derivatives, chemical synthesis of main derivatives, enzymatic characterization of individual biochemical steps and detailed homology modelling of enzyme complexes were performed. This allowed us to show the primary metabolism-derived malonyl CoA-ACP transacylase (AT) FabD acting as trans-AT in the biosynthesis, suggest an order for all late-stage modifications and provide a function for the three conserved hypothetical proteins PipDFG acting as last-step acetylation complex thereby stabilizing the final product.

microbiology↗

bioRxiv2023

The role of cuticular hydrocarbons in intraspecific aggression in the invasive ant Cardiocondyla obscurior

Cuticular hydrocarbons (CHCs) are important cues for nestmate discrimination and intraspecific aggression in ants. In invasive ants, diminished CHC profile diversity is suspected to contribute to the ecological and evolutionary success of populations by reducing intraspecific aggression between colonies. The ant Cardiocondyla obscurior has successfully colonized habitats around the world, reaching high local population densities. However, despite being invasive, colonies still react aggressively against each other, especially in interactions with non-nestmate alate queens. Here, we study whether CHCs are relevant for antagonistic interactions in this species, by combining behavioral experiments with gas-chromatography coupled with mass spectrometry (GC-MS). We show that queen and worker CHC profiles show pronounced quantitative as well as qualitative differences, that queens with depleted CHC profiles receive virtually no aggression from non-nestmates, and that aggression levels are positively correlated with the naturally occurring CHC profile differences between colonies. These findings provide first empirical evidence for a role of CHCs and chemical diversity in antagonistic behaviors against foreign queens in this species. They further suggest that invasive populations of C. obscurior are multicolonial and polydomous.

animal behavior and cognition↗

bioRxiv2023

Decoding the genetic and chemical basis of sexual attractiveness in parasitic wasps

Attracting and securing potential mating partners is of fundamental importance for successfully initiating reproduction and thus assuring the passing of genes to the next generation. Therefore, signaling sexual attractiveness is expected to be tightly coordinated in communication systems synchronizing senders and receivers. Chemical signaling has permeated through all taxa of life as the earliest and most wide-spread form of communication and is particularly prevalent in insects. However, it has been notoriously difficult to decipher how exactly information related to sexual signaling is encoded in complex chemical profiles. Similarly, our knowledge of the genetic basis of sexual signaling is very limited and usually restricted to a few case studies with comparably simple pheromonal communication mechanisms. The present study jointly addresses these two knowledge gaps by characterizing a single gene simultaneously impacting sexual attractiveness and complex chemical surface profiles in parasitic wasps. Knocking down a fatty acid synthase gene in female wasps dramatically reduces their sexual attractiveness coinciding with a drastic decrease in male courtship and copulation behavior. Concordantly, we found a striking shift of methyl-branching patterns in the female surface pheromonal compounds, which we subsequently demonstrate to be the main cause for the greatly reduced male response. Intriguingly, this suggests a potential coding mechanism for sexual attractiveness mediated by specific methyl-branching patterns, whose genetic underpinnings are not well understood despite their high potential for encoding information. Our study sheds light on how biologically relevant information can be encoded in complex chemical profiles and on the genetic basis of sexual attractiveness. Significance StatementUnraveling the genetic basis of chemical signaling is one of the most prevalent yet challenging topics in functional genetics and animal communication studies. Here we present the characterization of a biosynthetic gene in parasitoid wasps that simultaneously impacts sexual attractiveness as well as majorly shifts complex surface pheromone compositions. The shifted pattern primarily constitutes up- and down-regulated methyl-branched compounds with very distinct branching positions. Therefore, these findings immediately suggest a potential coding mechanism for sexual attractiveness in complex chemical profiles. This advances our understanding of how genetic information can be translated into biologically relevant chemical information and reveals that sexual attractiveness can have a comparably simple genetic basis.

genetics↗

bioRxiv2021

Genetic and genomic architecture of species-specific cuticular hydrocarbon variation in parasitoid wasps

Cuticular hydrocarbons (CHCs) serve two fundamental functions in insects: protection against desiccation and chemical signaling. CHC profiles can consist of dozens of different compounds and are considered a prime example for a complex trait. How the interaction of genes shapes CHC profiles, which are essential for insect survival, adaptation, and reproductive success, is still poorly understood. Here we investigate the genetic and genomic basis of CHC biosynthesis and variation in parasitoid wasps of the genus Nasonia. Taking advantage of the wasps haplo-diploid sex determination and cross-species fertility, we mapped 91 quantitative trait loci (QTL) explaining variation of a total of 43 CHCs in F2 hybrid males from interspecific crosses between three Nasonia species. To identify candidate genes, we localized orthologs of CHC biosynthesis-related genes in the Nasonia genomes. By doing so, we discovered multiple genomic regions where the location of QTL coincides with the location of CHC biosynthesis-related candidate genes. Most conspicuously, on a region on chromosome 1 close to the centromere, multiple CHC biosynthesis-related candidate genes co-localize with several QTL explaining variation in methyl-branched alkanes. The genetic underpinnings behind this compound class are not well understood so far, despite their high potential for encoding chemical information as well as their prevalence in both Nasonia CHC profiles and many other Hymenoptera. Our study considerably extends our knowledge on the so far little-known genetic and genomic architecture governing biosynthesis and variation of this fundamental compound class, establishing a model for methyl-branched alkane genetics in the Hymenoptera in general.

genetics↗