A new disruption observed in the white shrimp Penaeus vannamei caused by the absence of a trypsin allele

Abstract

In a previous study, the frequency of three different trypsin genotypes of Penaeus vannamei in aquaculture was described. Genotype CBA was the most abundant, followed by genotype CB, but genotype CA decreased its frequency and was not found in shrimps higher than 5 g of body weight. The conclusion was that shrimp with genotype CA inexplicably die under culture conditions. The question was if the process of shrimp aquaculture exerts excess pressure on the CA organisms, will they die? or will they die no matter where they grow?. To answer this question, the trypsin genotype frequencies in 60 breeder shrimp of a natural population were analyzed to predict the trypsin genotype frequency in the next generation. Then, a total of 1000 P. vannamei shrimp within the F1 generation of the same natural population weighing 2, 3, 5, 7 and 15 g were collected for 5 months, and the trypsin genotype frequencies were recorded. The results indicate that the F1 is out of Hardy–Weinberg equilibrium, and the absence of genotype CA in the natural population is similar to that in aquaculture. In conclusion, the process of aquaculture does not exert pressure on the CA genotype; such mortality is associated with another phenomenon not yet understood and deserving of further examination. At the moment, we know that the mortality occurs when shrimp inherit a trypsin codominant allele monomorphic called A, and the absence of allele B, and thus, we named the phenomenon “NON-B disruption”.