Embryonic and Larval Development and Effect of Salinity Levels on Egg and Ovary Performance in Rabbit Fish (Siganus guttatus)

In this study we investigated embryonic and larval development of rabbit fish (Siganus guttatus) in captivity. Embryonic development lasted 18-19 hours at 28-30oC, pH: 7.6-8.0, salinity: 30-32‰. Average total length of larvae at day 1 after hatching (DAH) was 1.58 mm, average yolk sac length was 0.35 mm containing one yolk ellipsoid (0.92±0.146 mm in length and 0.54±0.107 mm in width) in dorsal and lateral views. At day 2 (DAH) larval length increased to 2.16 mm, and pigmented eyes, mouth, and caudal-fin rays developed. Day 3 (DAH) larval length was 2.25 mm and the yolk was completely absorbed. Our findings provide fundamental information regarding seed larvae production of rabbit fish. In a further experiment we investigated the effect of salinity on gonad maturation, gonadosomatic index (GSI), egg biochemical composition and fecundities. Broodfish were cultured in three salinities, 25, 30, and 35‰ during reproductive season from February to July 2015. No statistically significant effects on gonadal development, fecundities, and egg quality in rabbit broodfish held in different salinities during the reproductive season were foun

Evaluation of Pseudomonas stutzeri AM1 and Pseudomonas oleovorans ST1.1 isolated from shrimp pond sediments as probiotics for whiteleg shrimp, Litopenaeus vannamei culture

This study aimed to isolate the probiotic potential of nitrifying bacterial strains and to evaluate their effects on water quality and growth performance of the whiteleg shrimp, Litopenaeus vannamei. Based on an initial screening of 100 isolates identified from sediment samples, 12 strains could remove nitrogen compounds and two strains (Pseudomonas stutzeri AM1 and P. oleovorans ST1.1) showed highly efficient nitrogen removal ability. Within 96 h, total ammonia nitrogen (TAN) removal efficiency in the two strains was 28.0-31.6% and 21.5-24.9%, respectively. The water addition of 103 CFUmL-1 of P. stutzeri AM1 (T1) and P. oleovorans ST1.1 (T2) effectively reduced TAN, nitrite, nitrate, and total sulfide and increased the survival rate and biomass of shrimp. However, no significant differences were found between the control (T0) and treatment groups (T1 and T2) in the final weight, weight gain and specific growth rate of shrimp. Overall, P. stutzeri AM1 (T1) and P. oleovorans ST1.1 used as water supplements improved water quality and the survival rate of whiteleg shrimp

Visualization of Allostery in P-Selectin Lectin Domain Using MD Simulations

Allostery of P-selectin lectin (Lec) domain followed by an epithelial growth factor (EGF)-like domain is essential for its biological functionality, but the underlying pathways have not been well understood. Here the molecular dynamics simulations were performed on the crystallized structures to visualize the dynamic conformational change for state 1 (S1) or state 2 (S2) Lec domain with respective bent (B) or extended (E) EGF orientation. Simulations illustrated that both S1 and S2 conformations were unable to switch from one to another directly. Instead, a novel S1' conformation was observed from S1 when crystallized B-S1 or reconstructed “E-S1” structure was employed, which was superposed well with that of equilibrated S1 Lec domain alone. It was also indicated that the corresponding allosteric pathway from S1 to S1' conformation started with the separation between residues Q30 and K67 and terminated with the release of residue N87 from residue C109. These results provided an insight into understanding the structural transition and the structure-function relationship of P-selectin allostery