Estimation of RNA/DNA ratio at early stages of larval development from crosses of Iranian sturgeon (Acipenser persicus) in a factorial design

RNA/DNA ratio analysis (R/D) is used as a quick and efficient tool to determine fish growth status. Therefore, this study aimed to estimate the R/D ratio in larvae produced from crossing of three females with three wild male sturgeons Acipenser persicus breeders caught from the southern shores of the Caspian Sea in Guilan province were done in a 3×3 factorial experimental design. Nine treatments including F1M1, F1M2, F1M3, F2M1, F2M2, F2M3, F3M1, F3M1, F3M2 and F3M3 crosses were created (each treatment with three replications). The larvae obtained from these treatments were kept at the same temperature and nutritional conditions for 120 days. The larvae were sampled at four stages during the experiment to estimate the R/D ratio. Data analysis was performed to determine the normality of the data first and then using one-way and two-way variances of type 3 (TYP III) to determine the interaction between sampling time with R/D ratio and significant tests. Tukey and Excel software, SPSS20, were performed. The results showed that the R/D ratio increased with the growth of fish so that stage K (120 days after hatching) had the highest R/D ratio. The highest R/D ratio of treatment 5 (F2M2) was 0.939 ± 0.06 and the lowest was 0.55 0 0.02 ng/ml in treatment 2 (F1M2). In conclusion, it can be concluded that the concentration of RNA and DNA increased rapidly with increasing Iranian sturgeon age, followed by an increase in the R/D ratio in fish that responds to fish nutrition status, it can be attributed to dietary changes during larval rearing. Accordingly, it can be concluded that estimating the R/D ratio can provide useful information on the growth and nutrition status of larvae.