Biology subjects

Donner, I.

Publications and source records attributed to Donner, I..

5 recordsLinked to original sources

bioRxiv2024

Sex-, development-, and nutrition-dependent expression of a major age-at-maturity gene in Atlantic salmon

Sexual maturation is a key process in the life history of an organism and is influenced by both genetic and environmental factors. In Atlantic salmon (Salmo salar), alternative alleles at the gene vgll3 have been found to associate with a large proportion of the variation in maturation age, yet the molecular and physiological mechanisms of this association are still largely unknown. Here, we investigated the mechanisms by which genetic variation in this major age-at-maturity gene translated into phenotypic variation. We established a time series of gonadal vgll3 mRNA expression in male and female Atlantic salmon in a common garden setting, starting at the prepubertal stage and spanning multiple spawning seasons. We found that vgll3 mRNA expression is reduced in early-maturing males and females. However, for the second spawning season, vgll3 expression increased with gonadal development in males, but eventually decreased in females. Expression of vgll3 had context-dependent correlations with expression of amh and lhr. We also found signs of reduced testicular vgll3 expression in a low-fat feed treatment. By significantly widening the scope of our knowledge on temporal vgll3 expression dynamics, our results exemplify that major-effect genes may use different pathways in sexes but achieve similar outcomes.

genetics↗

bioRxiv2024

A complex mechanism translating variation of a simple genetic architecture into alternative life-histories

Linking genes to traits is a central goal in biology. Despite progress in discovering genes associated with trait differences, a poor understanding of the functional mechanisms underlying genetic associations leaves us critically far from connecting genetic and phenotypic variation. This knowledge-gap is particularly large in multifaceted phenotypes of ecological relevance such as life-history traits. Using a multiomic dissection of the genotype-phenotype association in a large-effect maturation age gene - the transcription cofactor vestigial-like 3 (vgll3) - in Atlantic salmon (Salmo salar), we show that vgll3 mediates concerted changes of distinct molecular phenotypes associated with puberty in male gonads. Vgll3 genotype conferring early maturity upregulates key genes controlling androgen production, cellular energy and adiposity, and TGF-{beta} signaling, among others, thereby increasing the likelihood of earlier pubertal initiation. Genotype-dependent developmental trajectories are produced through VGLL3 interaction with distinct transcription factors, thus coordinating differential activation of regulatory pathways. These results reveal a genetically simple, yet functionally complex, architecture underlying alternative life-histories where variation in a single major effect gene produces pleiotropic variation in a spectrum of cellular traits. Our results further suggest that evolution in correlated phenotypes such as exemplified by alternative life history strategies may be mediated by a surprisingly simple genetic architecture.

evolutionary biology↗

bioRxiv2023

Seasonal and genetic effects on lipid profiles of juvenile Atlantic salmon

Seasonality can influence many physiological traits requiring optimal energetic capacity for life-history stage transitions. In Atlantic salmon, high-energy status is essential for the initiation of maturation. Atlantic salmon lipid reserves are predominantly found in the viscera and myosepta in the muscle while the liver is essential for maintaining lipid metabolism. A genomic study found a region including a transcription co-factor-coding gene, vgll3, linked to Atlantic salmon maturation timing, which acts as an inhibitor of adipogenesis in mice, and mediates maturation via condition factor in Atlantic salmon. Here we investigate the influence of season and vgll3 genotypes associating with early (EE) and late (LL) maturation on lipid profiles in the muscle and liver in juvenile Atlantic salmon. We reared Atlantic salmon for two years until the occurrence of sexually mature males and sampled muscle and liver at two time points: spring and autumn of the second year. We found no seasonal or genotype effect in lipid profiles in muscle of immature males and females. However, in the liver we did detect a triacylglycerol (TG) enrichment and a genotype specific direction of change in membrane lipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), from spring to autumn. Specifically, from spring to autumn membrane lipid concentrations increased in vgll3*EE individuals and decreased in vgll3*LL individuals. This could be explained with two possible scenarios 1) a seasonally more stable capacity of endoplasmic reticulum (ER) functions in vgll3*EE individuals compared to vgll3*LL individuals or 2) vgll3*LL individuals storing larger lipid droplets from spring to autumn in the liver compared to vgll3*EE individuals at the expense of ER capacity. This genotype specific seasonal direction of change in membrane lipid concentrations provides more indirect evidence that a mechanism linking vgll3 with lipid metabolism and storage exists. HighlightsO_LISeasonal lipid species profile separation in muscle and liver in juvenile Atlantic salmon C_LIO_LIGenotype specific direction of change of membrane lipids from spring to autumn C_LIO_LIIndirect evidence that a mechanism linking vgll3 with lipid metabolism and storage exists C_LI

evolutionary biology↗

bioRxiv2022

A pituitary gene network linking vgll3 to regulators of sexual maturation in male Atlantic salmon

Age at maturity is a key life history trait and a significant contributor to life history strategy variation. The maturation process is complex and influenced by genetic and environmental factors alike, but specific causes of variation in maturation timing remain elusive. In many species, the increase in the regulatory gonadotropin-releasing hormone 1 (GnRH1) marks the onset of puberty. Atlantic salmon, however, lack the gene encoding GnRH1, suggesting other regulatory factors are involved in the maturation process. Earlier research in Atlantic salmon has found a strong association between alternative alleles of vgll3 and maturation timing, making vgll3 a candidate reproductive axis gene regulator. Recently we reported strong induction of gonadotropin encoding genes (fshb and lhb) in the pituitary of male Atlantic salmon homozygous for the vgll3 allele linked with the early maturation allele (E). The induction of gonadotropins was accompanied by increased expression of their direct upstream regulators, c-jun and sf1 (nr5a1b) in the pituitary. In mammals, the transcriptional activation of c-jun and sf1 is also required for induction of fshb and lhb, however, GnRH1 is responsible for increased transcriptional activity of c-jun and sf1. The absence of gnrh1 in salmon raises the possibility of the involvement of other regulators upstream of these factors. In this study, we investigated such a possibility through a stepwise approach for identifying a gene regulatory network (GRN) containing c-jun and sf1 and using the zebrafish coexpression database and transcription factor motif enrichment analysis. We found a GRN containing c-jun with predicted upstream regulators, e2f1, egr1, foxj1 and klf4, which are also differentially expressed in the pituitary. Finally, we suggest a model for transcriptional regulation of c-jun and sf1in the absence of gnrh1 in the pituitary, which may have broader implications across vertebrates.

molecular biology↗

bioRxiv2017

BasePlayer: Versatile Analysis Software For Large-Scale Genomic Variant Discovery

Next-generation sequencing (NGS) is being routinely applied in life sciences and clinical practice, where the interpretation of the resulting massive data has become a critical challenge. Computational workflows, such as the Broad GATK, have been established to take raw sequencing data and produce processed data for downstream analyses. Consequently, results of these computationally demanding workflows, consisting of e.g. sequence alignment and variant calling, are increasingly being provided for customers by sequencing and bioinformatics facilities. However, downstream variant analysis, whole-genome level in particular, has been lacking a multi-purpose tool, which could take advantage of rapidly growing genomic information and integrate genetic variant, sequence, genomic annotation and regulatory (e.g. ENCODE) data interactively and in a visual fashion. Here we introduce a highly efficient and user-friendly software, BasePlayer (http://baseplayer.fi), for biological discovery in large-scale NGS data. BasePlayer enables tightly integrated comparative variant analysis and visualization of thousands of NGS data samples and millions of variants, with numerous applications in disease, regulatory and population genomics. Although BasePlayer has been designed primarily for whole-genome and exome sequencing data, it is well-suited to various study settings, diseases and organisms by supporting standard and upcoming file formats. BasePlayer transforms an ordinary desktop computer into a large-scale genomic research platform, enabling also a non-technical user to perform complex comparative variant analyses, population frequency filtering and genome level annotations under intuitive, scalable and highly-responsive user interface to facilitate everyday genetic research as well as the search of novel discoveries.

bioinformatics↗