Effects of supplementation of coated crystalline amino acids on growth performance and body composition of juvenile kuruma shrimp Marsupenaeus japonicus

Supplementation of crystalline amino acids (CAA) in shrimp diets is unsuccessful in most cases. In the present study, various pre‐coated CAA were developed to minimize the leaching losses from diets in water and assessed using kuruma shrimp Marsupenaeus japonicus juveniles. Experimental diets were supplemented with coated CAA or non‐coated CAA to simulate the dietary amino acid profile to that found in the whole body protein of shrimp. The four diets contained CAA coated with either carboxymethyl cellulose (CMC) (diet 1), zein (diet 2), k‐carrageenan (diet 3) or agar (diet 4), respectively. Another four diets contained CMC‐coated CAA with the addition of either zein (diet 5), casein‐gelatin (diet 6), zein and k‐carrageenan (diet 7), or casein‐gelatin and k‐carrageenan (diet 8), respectively. The 8 weeks feeding trial demonstrated that the diets containing coated CAA gave significantly higher weight gains than diets containing non‐coated CAA, with the highest value for the diet 6. The diets containing coated CAA also yielded higher feed conversion efficiency, protein efficiency ratio, and specific growth rate than diets containing non‐coated CAA. Leaching trials suggested that shrimp growth performance was improved partly due to the retardation or reduction of CAA leaching by coating them with specific binders.     

Structure and molecular mechanism of a nucleobase-cation-symport-1 family transporter

The nucleobase-cation-symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved, showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine transporter LeuT(Aa) and the galactose transporter vSGLT reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronized by the inverted repeat helices 3 and 8, providing the structural basis of the alternating access model for membrane transport.     

Effects of Animal Proteins in Practical Diets on Growth and Economic Performance of Climbing Perch,Anabas testudineus (Bloch)

A ten-week feeding trial was carried out to evaluate animal proteins, either alone or in combination (1:1:1), on the growth performances and economic benefit of climbing perch, Anabas testudineus. Four iso-proteinous (40%) diets were prepared, using fishmeal, protein concentrate, and meat and bone meal as major protein source in diets 1, 2 and 3, respectively, while diet 4 consisted of an equal proportion (1:1:1) of the above protein sources. Triplicate groups of fish (0.53 ± 0.02 g) were randomly stocked in 12 earthen ponds at a stocking density of 40,000 ha^?1. Fish fed diet 4 had significantly (P < 0.05) higher percent weight gain and SGR % per day^?1 compared to the fish fed diets 1, 2, or 3. Significantly higher apparent protein efficiency ratio (1.25) and lower apparent feed conversion ratio (2.00) were also observed in fish fed diet 4. Total yield (1,123 kg ha^?1) and net profit (Tk. 116,569 ha^?1) were also higher in fish fed diet 4. It can be concluded that the combination of fishmeal, protein concentrate, and meat and bone meal is more effective for climbing perch than any of the three protein sources alone.