Identification and molecular characterization of Cathepsin L gene and its expression analysis during early ontogenetic development of kuruma shrimp Marsupenaeusjaponicus

Cathepsin L gene is a member of the cysteine proteinase gene group. In this study Cathepsin L gene was isolated from Kuruma shrimp Marsupenaeusjaponicus （Mj-Cathepsin L） and the full-length DNA sequence was 1 963 bp. Mj-Cathepsin L protein showed high homologies with other Cathepsin L proteins documented in vertebrates, mollusks and other crustaceans. Expression analysis of Mj-Cathepsin L gene in different tissues revealed that it was predominant in hepatopancreas. During early ontogenetic development stages Mj-Cathepsin L showed a development-regulated expression, and the Mj-Cathepsin L showed a molting stage-regulated expression during the five molting stages, inferring its role in the ontogenic development of M.japonicus. Two kinds of forms of Mj- Cathepsin L protein： pro-Cathepsin L and Cathepsin L were measured in hepatopancreas, stomach and intestine by Western Blotting.

Layered farming for Marsupenaeus japonicus Bate

Marsupenaeusjaponicus Bate is one of the most valuable cultured shrimp species in China and outdoor earthen pond farming is the most common method of culturing this organism. The need to increase soil usage efficiency in aquaculture has been recognized and a great deal of research effort has been directed toward development of super-intensive farming systems. However, current research and development in this field is largely devoted to Litopenaeus vannamei Boone, while to M.japonicus Bate it has been neglected. In this study, a layered fanning system was designed and a 66-day study was conducted in M.japonicus Bate culture. The system comprised bracket and sand layers that divided a shrimp tank filled to a depth of 1.2 m into four water layers. Conventional tank culture （unlayered） was used as a control. The results show that survival rate, feed conversion efficiency and production of M.japonicus Bate in the layered farming system were 68%, 18%, and 0.59 kg/m^2, respectively, all of which are significantly higher than in the unlayered fanning system （P〈0.01）. These findings confirmed the possibility of using a layered system to culture M. japonicus Bate.

Variations of Ion-Transport Enzyme Activities During Early Development of the Shrimps Fenneropenaeus chinensis and Marsupenaeus japonicus

The ion-transport enzyme activities were studied in the nauplii 1-2, zoea 1-3, mysis 1-3, and postlarva 1-7 of the shrimps Marsupenaeus japonicus and Fenneropenaeus chinensis. The results showed that total ATPase, Na＋-K＋-ATPase, and V-ATPase （V-type H＋-ATPase） activities increased during the early development for both the species, from zero in nauplii to stable levels after zoea stage. The enzyme activities of the latter species were significantly higher than those of the former species after zoea stage （F〉F0.05）. The contributions of Na＋-K＋-ATPase, V-ATPase and HCO3--ATPase to the total ATPase activity of the two species varied in different developmental stages and accounted for 40%-70%, 22%-46% and 2%-13% in M. japonicus from zoea to postlarva stage, whilst the shares of them were 42%-69%, 28%-44% and 2.5%-22%, respectively in Echinensis. These findings suggest the possible culture of the two species with varying water quality, especially the salinity and pH.