Differential expression following ammonia stress and growth-related SNP of ferritin: Applications for establishment of stress-tolerant stocks with high growth performance of Pacific white shrimp Litopenaeus vannamei in Thailand

Abstract

Effects of ammonia challenge on expression of ferritin (LvFer) transcripts in Pacific white shrimp Litopenaeus vannamei were examined. One family of second generation (G2) of a growth-improved stock was generated and subjected to a non-lethal ammonia stress test (control, 10 and 20 mg/l ammonia-N). The expression level of LvFer transcripts in hemocytes and hepatopancreas of L. vannamei juveniles during a 72 h trial was significantly changed after exposed to 20 mg/l ammonia-N compared to the control (unchanged water). In addition, a lethal dose challenge (32.15 mg/l ammonia-N) was carried out. The expression levels of LvFer transcripts in susceptible (died before 72 h post treatment, hpt) was significantly lower than that of tolerant (survived after 72 hpt) shrimp (P < 0.05). One single nucleotide polymorphism (SNP, T>G 208) was found in the LvFer gene segment. Real-time PCR amplification of specific alleles (real-time PASA) was successfully developed for genotyping of a T>G 208 SNP. The expression level of juveniles in the tested family carrying a T/T 208 genotype was greater than those carrying a T/G 208 genotype. Association analysis was further tested in a genetically improved stock (4 full-sib families). Juveniles with a T/T 208 genotype showed a greater average body weight and total length than those with a T/G 208 genotype. The expression level of LvFer can be further applied for selection of ammonia-tolerant families while its SNP can be used for selection of shrimp families with a better growth performance in our on-going breeding program of L. vannamei.