Figure 1.
Experimental design to obtain a genetically female (XX) population in order to study temperature effects on the male proportion in a selected line of Nile tilapia.
Figure 2.
Gene structure, pairwise linkage disequilibrium (r2) between SNPs, and functional annotation of the Nile tilapia amh gene derived from the Ensembl database.
a) Gene structure of the amh gene derived from Scaffold GL831234.1. Exons 1–7 (E1–7) are represented by filled grey boxes. Blue and red dashed lines show positions of polymorphic SNPs in the amh gene. SNP ss831884015 (C>T) is located −225 bp upstream of the start codon ATG, SNP ss831884018 was located in the intron between exon 6 and 7. Variants ss831884014 and ss831884019 were found in exons 6 and 7. SNP ss831884014 (G>C) and ss831884019 (C>T) were missense mutations leading to amino acid changes from glutamic acid to glutamine (codons Gaa/Caa) and alanine to valine (codons gCg/gTg). Table 1 deals with the functional annotation of all six SNPs. b) Pairwise linkage disequilibrium heat map of four polymorphic allelic variants in the Nile tilapia amh gene. c) Partial DNA to protein translation of exon 6 in the Nile tilapia amh gene, depicting a non-synonymous amino acid substitution at position 376 of the putative amh-protein (indicated by black arrow) coded by an allelic variant ss831884014 of scaffold GL831234.1. d) Partial comparative alignment of the amh genomic exon 6 sequences for six teleost species derived from the Ensembl database. e) Partial comparative alignment of the amh protein sequence for six teleost species derived from the Ensembl database.
Table 1.
Functional annotation of six allelic variants in the Nile tilapia amh gene.
Table 2.
Allele frequencies, polymorphism information content (PIC), heterozygosity and allelic diversity for four allelic variants in the amh gene detected in a genetically all-female (XX) Nile tilapia population.
Table 3.
Effect of SNP ss831884014 genotypes, temperature treatment (28°C vs. 36°C from 10–20 dpf) and their interaction on the phenotypic sex in Nile tilapia.
Figure 3.
Relationship between male proportion and genotype at amh variant ss831884014 in Nile tilapia, reared at 28°C or 36°C from 10 to 20 days post fertilisation.
Linear least-square regression of the genotypic values (LSmean male proportion) for genotypes C/C, G/C, and G/G at locus ss831884014 of the amh gene (Scaffold GL831234.1). The genotypic values were derived from the regression models by either excluding the interaction between SNP and treatment (LSmeans 1: red and blue line) or by including the interaction between SNP and treatment (LSmeans 2: red and blue triangles) as effect class. Numbers of individuals per genotype were 26/79/20 and 114/144/47 for genotypes C/C, G/C, and G/G, for the control group (28°C) and the group reared at high temperature (36°C), respectively.
Table 4.
Dominance and additive effects of the variant ss831884014 on the male proportion in Nile tilapia reared at 28°C or 36°C from 10–20 dpf.