My main research interests are molecular processes in organismic development and their malfunction in cancerogenesis.

One major topic of my laboratory is the understanding of signal transduction and gene regulation in cancer, in particular melanoma. Malignant melanoma is one of the most dangerous tumors with an incidence rising faster than any type of cancer worldwide. We use the classical Xiphophorus model system and transgenic medaka that develop different types of pigment cell tumors. With the established tools of biochemistry and molecular genetics as well as high throughput and deep sequencing methods (RNA-seq, CHiP-seq, RAD-tags) we want to better understand the molecular mechanisms that make a normal pigment cell turn into a malignant cancer cells and provide on this basis novel approaches for better diagnoses and therapies.

A second major interest is in the molecular basis and evolution of sex determination. Sex can be determined by a plethora of mechanisms and the different mechanisms do not follow a phylogenetic pattern. Particularly in fish, sex determination is highly variable, sometimes even among closely related species. We want to understand the reasons why this variability exists and what molecular changes are involved. We use a comparative approach studying various fish species. This includes developmental biological studies on the processes that make the decision in the embryo or larvae if the undifferentiated bipotential gonad will develop either as testis or ovary laboratory model fish species. Besides we try to identify the unknown sex determination genes from fish that are representing major branches of the fish tree of life and are of interest because of special ecological, evolutionary or economic features.

Because the function of any gene is shaped by its evolutionary history and its genomic context we are interested in the evolution of genes involved in cancer, pigmentation, sex determination and reproductive development. The opportunities offered by the next generation sequencing technologies allow to obtain the full genome information now also for interesting species besides the mainstream laboratory models, which offers new insights into their evolution and biology.

We are members of several international consortia (some initiated and coordinated by us) for the de-novo sequencing, assembly and annotation of fish genomes, which include our melanoma model organism, the platyfish Xiphophorus maculatus, the Amazon molly, a unisexual clonal fish species, two marine flatfish, two cyprinid species, the coelacanth Latimeria chalumnae, the lungfish and several others. We analyze the genomes with a special attention to the evolution of genes and gene families, which are of our interest from the cancer projects and the evolution of sex determination mechanisms and sex chromosomes. Major focuses are gene and whole genome duplications as important drivers of evolutionary innovations and adaptations. We are also interested how several traits like secondary sex characters, the age of sexual maturation (puberty) or pigmentation patterns evolve and have an impact on speciation.

1. Abdulsahib, S, Boswell, W, Boswell, M, Savage, M, Schartl, M, Lu, Y et al.. Transcriptional background effects on a tumor driver gene in different pigment cell types of medaka. J Exp Zool B Mol Dev Evol. 2023; :. doi: 10.1002/jez.b.23224. PubMed PMID:37877158 .
2. Sendell-Price, AT, Tulenko, FJ, Pettersson, M, Kang, D, Montandon, M, Winkler, S et al.. Low mutation rate in epaulette sharks is consistent with a slow rate of evolution in sharks. Nat Commun. 2023;14 (1):6628. doi: 10.1038/s41467-023-42238-x. PubMed PMID:37857613 PubMed Central PMC10587355.
3. Zhu, T, Kong, M, Yu, Y, Schartl, M, Power, DM, Li, C et al.. Exosome delivery to the testes for dmrt1 suppression: A powerful tool for sex-determining gene studies. J Control Release. 2023;363 :275-289. doi: 10.1016/j.jconrel.2023.09.027. PubMed PMID:37726035 .
4. Schartl, M. What the genome of the leafy seadragon teaches us about rapid evolution of camouflage and adaptations to life in the kelp forest. Sci China Life Sci. 2023;66 (11):2692-2693. doi: 10.1007/s11427-023-2368-9. PubMed PMID:37405566 .
5. Müller, S, Du, K, Guiguen, Y, Pichler, M, Nakagawa, S, Stöck, M et al.. Massive expansion of sex-specific SNPs, transposon-related elements, and neocentromere formation shape the young W-chromosome from the mosquitofish Gambusia affinis. BMC Biol. 2023;21 (1):109. doi: 10.1186/s12915-023-01607-0. PubMed PMID:37189152 PubMed Central PMC10186657.
6. Lu, Y, Rice, E, Du, K, Kneitz, S, Naville, M, Dechaud, C et al.. High resolution genomes of multiple Xiphophorus species provide new insights into microevolution, hybrid incompatibility, and epistasis. Genome Res. 2023;33 (4):557-571. doi: 10.1101/gr.277434.122. PubMed PMID:37147111 PubMed Central PMC10234306.
7. Schartl, M, Georges, A, Marshall Graves, JA. Polygenic sex determination in vertebrates - is there any such thing?. Trends Genet. 2023;39 (4):242-250. doi: 10.1016/j.tig.2022.12.002. PubMed PMID:36669949 PubMed Central PMC10148267.
8. Li, S, Li, W, Jiang, S, Jing, Y, Xiao, L, Yu, Y et al.. Mechanisms of sex differentiation and sex reversal in hermaphrodite fish as revealed by the Epinephelus coioides genome. Mol Ecol Resour. 2023;23 (4):920-932. doi: 10.1111/1755-0998.13753. PubMed PMID:36631404 .
9. Schartl, M, Lamatsch, DK. How to manage without a Y chromosome. Proc Natl Acad Sci U S A. 2023;120 (2):e2218839120. doi: 10.1073/pnas.2218839120. PubMed PMID:36598951 PubMed Central PMC9926260.
10. Dedukh, D, da Cruz, I, Kneitz, S, Marta, A, Ormanns, J, Tichopád, T et al.. Achiasmatic meiosis in the unisexual Amazon molly, Poecilia formosa. Chromosome Res. 2022;30 (4):443-457. doi: 10.1007/s10577-022-09708-2. PubMed PMID:36459298 PubMed Central PMC9771850.