LAUSR

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 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.