Analysis of SNP (400 c > a) in the IGF1 gene for associations with size and weight indicators of sterlet (Acipenser ruthenus, Linnaeus, 1758)

Sterlet (Acipenser ruthenus , Linnaeus, 1758) is an important species of sturgeon bred in aquaculture, since it is characterized by early sexual maturity and adapts well to the conditions of maintenance. In commercial aquaculture, the demand for breeding sterlet which has a high growth rate is increasing to obtain the greatest economic effect. The study of associations between polymorphisms in candidate genes and productivity indicators is a convenient and effective approach to identify molecular markers that affect polygenic traits. Insulin-like growth factor 1 (IGF1) plays an important role in the growth and development of vertebrates, so the identification of polymorphisms significantly associated with growth characteristics may be useful in genetic improvement of aquaculture sterlet populations. In the present work, we sequenced cDNA of paralogous insulin-like growth factor 1 genes of sterlet for the first time and identified a non-synonymous polymorphism 400 C > A in exon 1 and a synonymous SNP 479 C > A in exon 2 on chromosome 7, and also investigated the effect of the genotype for SNP 400 C > A of the IGF1 gene on the size and weight indicators of sterlet. Our goal was to study the polymorphism of the coding part of the IGF1 gene by cDNA sequencing, identify SNPs and evaluate associations between genotypes and size-weight indicators of sterlet. The studies were conducted in 2023 on the Sukhonskaya (n = 58) and Oka (n = 44) sterlet populations bred in the recirculating aquaculture system (the Ernst Federal Research Center for Animal Husbandry). The Oka sterlet population of was provided by the Mozhaisk production and experimental fish hatchery (Mozhaisk urban District, Moscow Province), the Sukhon sterlet population by OOO RTF Diana (Kaduysky district, Vologda Province). The fish were chipped and a database was created to enter the grading results. Measurements were made for 11 morphometric features. Total RNA was isolated from fragments of the liver, brain, muscle, heart and blood using the RNA-EKSTRAN reagent kit (NPO Sintol, Russia). The synthesis of the first DNA strand on the RNA matrix was performed using a reagent kit for reverse transcription (NPO Sintol, Russia). Genomic DNA was extracted from fin fragments preserved in alcohol using the DNA-EKSTRAN genomic DNA isolation kit (NPO Sintol, Russia). PCR was performed on a Thermal Cycler SimpliAmp amplifier (Thermo Fisher Scientific, Inc, USA). Detection of PCR results was performed in 1-2 % agarose gel using the Uvitec FireReader V10 imaging system (Cleaver Scientific, UK). Acipenser ruthenus belongs to tetraploid species, therefore, specific primers were selected for two paralogous genes localized on chromosomes 7 and 14. DNA sequences were determined by Sanger sequencing on a Nanofor 05 genetic analyzer (NPO Sintol, Russia) with the GenSeq kit (NPO Sintol, Russia) according to the manufacturer's instructions. Gene polymorphism (C > A at position 400 Accession No. XM_034024781.3) was determined by real-time PCR (RT-PCR) on a QuantStudio 5 device (Thermo Fisher Scientific, USA). The obtained nucleotide sequences of genes was processed using special Mega7 software. After multiple alignment, non-synonymous (400 C > A) and synonymous (479 G > A) single nucleotide polymorphisms (chromosome 7) were identified. Non-synonymous mutation at position 400 C > A resulted in the replacement of the amino acid proline (CCT triplet) by histidine (CAT triplet) and, as a consequence, in a change in the spatial structure of the protein and its functions. Association studies of genotypes for the 400 C > A locus with the size and weight characteristics of sterlet showed that fish with the CC genotype had a significantly larger body weight, total length, body length to the end of the middle rays, pectroventral distance and the largest body girth (p A SNP on the total length of sterlet (p A polymorphism of the IGF1 gene can be considered as a potential genetic marker in sterlet selection for growth parameters. However, we believe it is necessary to conduct additional association studies on a larger population, as well as to study the influence of complex genotypes on growth indicators.