Biology subjects

Podobnik, M.

Publications and source records attributed to Podobnik, M..

7 recordsLinked to original sources

bioRxiv2026

Divergence in skeletal muscle growth by differential spatial hyperplastic patterning in teleost fishes

Skeletal muscle plays important locomotive and metabolic functions, yet its formation and maintenance are processes remaining largely unclear mechanistically in any animal. Teleost fishes display extraordinary muscle growth due to their ability to undergo both hyperplasia and hypertrophy throughout life. These phenomena vary greatly even between closely related species, providing opportunities to elucidate growth dynamics and underlying mechanisms through cross-species comparisons. Using histological and genetic approaches, we compared muscle growth dynamics in three closely related danionin species with distinct growth capacities: the giant danio (Devario malabaricus), the zebrafish (Danio rerio), and Danionella cerebrum, as well as the more distantly related African turquoise killifish (Nothobranchius furzeri). Our study reveals alterations in spatial patterning of muscle hyperplasia and developmental timing to be major contributors to observed differences in muscle growth between examined species. Single-cell RNA profiling, in situ hybridization chain reaction and cell type-specific mutagenesis revealed muscle stem cell-specific expression of extracellular matrix genes that mediate stem cell activity, which in turn may drive growth differences between species. Taken together, our findings highlight autonomous regulation of muscle stem cells as a conserved but adaptable mechanism governing muscle patterning and diversification.

evolutionary biology↗

bioRxiv2025

Genomic and genetic insights into speciation and pigment pattern diversification in Danio fishes

The Danioninae subfamily of teleost fishes boasts up to four hundred distinct species that have evolved to display a stunning diversity of morphological forms. Here we use newly assembled genome sequences of four laboratory and wild zebrafish strains as well as eleven species of the Danio and Danionella genera to explore their phylogenetic history and the genetic basis of pigment pattern diversification. Phylogenomic analyses uncover extensive introgression and incomplete lineage sorting that have obscured phylogenetic relationships within Danio and corroborate an ancient hybrid origin of zebrafish. Whereas D. rerio inherited ancestral horizontal stripes, relatives repeatedly evolved spots and vertical bars. Interspecific complementation tests reveal functional divergence of the adhesion molecule gene igsf11 and the gap junction gene gja5b between the striped zebrafish and Danio species with divergent patterns. Comparative genomic and transcriptomic analyses suggest that protein and regulatory evolution have accompanied pigment pattern diversification. Our analyses elucidate complex genetic changes underlying the phylogenetic history and morphological diversification in the Danio genus. Resolved phylogenetic relationships, available genome assemblies, transcriptomes, and genetic tractability establish Danio fish species as excellent models for biomedical research in vertebrates.

genomics↗

bioRxiv2025

Functionality of potato virus Y coat protein in cell-to-cell movement is defined by flexibility of its N terminal region

Potato virus Y (PVY) is one of the top ten economically most important plant viruses and responsible for major yield losses. We previously suggested the involvement of the N terminal region of potato virus Y coat protein (CP) in PVY spread. By constructing different N terminal deletion mutants of PVY N605 strain, we here show that deletions of 40 or more amino acid residues from the N terminal region of the CP resulted in the PVY multiplication limited to primary infected cells in Nicotiana clevelandii plants. Deletion of 26 residues profoundly impaired PVY cell-to-cell movement and prevented systemic PVY spread, while deletions of 19-23 residues allowed delayed systemic PVY spread. Introduced point mutations in the identified region prevent (S21G) or delay (G20P) PVY movement. In summary, this work shows the significance of the CP N-terminus for movement of the PVY.

plant biology↗

bioRxiv2024

High-resolution cryo-EM structures of a protein pore reveal diverse roles of membrane lipids

The structure and function of membrane proteins depend on their interactions with the lipid molecules that constitute lipid membranes. Actinoporins are a family of -pore-forming proteins that bind specifically to sphingomyelin-containing lipid membranes, where they oligomerize and form transmembrane pores. The numerous contacts they form with the lipid membrane make them an exemplary object for studying the different roles that lipids play in the structure and function of membrane proteins. Through a comprehensive cryo-electron microscopic analysis of a pore formed by an actinoporin Fav from the coral Orbicella faveolata, we show that the octameric pore interacts with 112 lipids in the upper leaflet of the membrane. The structures of Fav pores formed on different lipid membranes reveal the different roles of lipids and demonstrate that the actinoporin surface is perfectly suited for binding multiple receptor sphingomyelin molecules. When cholesterol is present in the membrane, it forms nanodomains associated with the pore, leading to a tighter arrangement of lipids, which in turn increases the stability of the pores. Atomistic simulations support the structural data, show that the protein-bound lipids are not mobile, and reveal additional effects of the pore on the lipid membrane. Overall, these data reveal a complex network of protein-lipid and lipid-lipid interactions, and an underrated role of lipids in the structure and function of transmembrane protein complexes.

biochemistry↗

bioRxiv2023

Efficient genome editing using modified Cas9 proteins in zebrafish

The zebrafish (Danio rerio) is an important model organism for basic as well as applied bio-medical research. One main advantage is its genetic tractability, which was greatly enhanced by the introduction of the CRISPR/Cas method a decade ago. The generation of loss-of-function alleles via the production of small insertions or deletions in the coding sequences of genes with CRISPR/Cas systems is now routinely achieved with high efficiency. The method is based on the error prone repair of precisely targeted DNA double strand breaks by non-homologous end joining (NHEJ) in the cell nucleus. However, editing the genome with base pair precision, by homology-directed repair (HDR), is by far less efficient and therefore often requires large-scale screening of potential carriers by labour intensive genotyping. Here we show that the Cas9 protein variant SpRY with relaxed PAM requirement can be used for gene targeting in zebrafish, thus expanding the versatility of the method. In addition, we demonstrate that the incorporation of an artificial nuclear localisation signal (aNLS) into the Cas9 protein variants not only enhances the efficiency of gene knock-out but also the frequency of HDR thereby facilitating the efficient modification of single base pairs in the genome. Our protocols provide a guide for a cost-effective generation of versatile and potent Cas9 protein variants and efficient gene editing in zebrafish.

genetics↗

bioRxiv2022

Cis-regulatory evolution of the potassium channel gene kcnj13 during pigment pattern diversification in Danio fish

Teleost fish of the genus Danio are excellent models to study the genetic and cellular bases of pigment pattern variation in vertebrates. The two sister species Danio rerio and Danio aesculapii show divergent patterns of horizontal stripes and vertical bars that are partly caused by the evolution of the potassium channel gene kcnj13. In D. rerio, kcnj13 is required in melanophores for interactions with xanthophores and iridophores, which cause location-specific pigment cell shapes and thereby influence colour pattern and contrast. Here, we show that cis-regulatory rather than protein coding changes underlie kcnj13 evolution between the two species. D. aesculapii express lower kcnj13 levels and exhibit low-contrast patterns similar to D. rerio mutants. Our results suggest that homotypic and heterotypic interactions between the pigment cells and their shapes diverged between species by quantitative changes in kcnj13 expression during pigment pattern diversification.

evolutionary biology↗

bioRxiv2020

Evolution of the potassium channel gene Kcnj13 underlies colour pattern diversification in Danio fish

The genetic basis of morphological variation provides a major topic in evolutionary biology1-6. Colour patterns in fish are among the most diverse of all vertebrates. Species of the genus Danio display strikingly different colour patterns ranging from horizontal stripes, to vertical bars or spots7-10. Stripe formation in zebrafish, Danio rerio, oriented by the horizontal myoseptum, is a self-organizing process based on cell-contact-mediated interactions between three types of chromatophores with a leading role of iridophores11-14. We investigated genes known to regulate chromatophore interactions in zebrafish as candidates that might have evolved to produce a pattern of vertical bars in its sibling species, Danio aesculapii8,10. Using gene editing15-17 we generated several mutants in D. aesculapii that demonstrate a lower complexity in the interactions between chromatophores in this species, as well as a minor role of iridophores in patterning. Complementation tests in interspecific hybrids18,19 identified obelix/Kcnj13, which encodes an inwardly rectifying potassium channel (Kir7.1)20, as a gene evolved between D. rerio and D. aesculapii as well as in two of seven more Danio species tested. Our results demonstrate that the CRISPR/Cas9-system allows straightforward genetic tests also in non-model vertebrates to identify genes that underlie morphological evolution.

evolutionary biology↗