In Chul Bang

Characterization and phylogeny of two β-cytoskeletal actins from Hemibarbus mylodon (Cyprinidae, Cypriniformes), a threatened fish species in Korea

Complementary DNA and genomic sequences representing two different β-actins were isolated from a threatened freshwater fish species Hemibarbus mylodon. The β-actin 1 and 2 encoded an identical number of amino acids (375 aa), and shared 88.8 and 99.7% of identity at coding nucleotide and amino acid levels, respectively. Genomic open reading frame (ORF) sequences of both isoforms contained five translated exons interrupted by four introns with conserved GT/AG exon/intron boundary rule. Semi-quantitative RT-PCR showed that the two isoform mRNAs were ubiquitously detected in all tissues tested, but transcript levels were variable across tissues. Phylogenetic analysis showed that H. mylodon β-actin 1 and 2 were clustered into two distinct major and minor branches of Cypriniformes, respectively. Comparisons of the 5′-upstream region and 3′-UTR of H. mylodon β-actin 1 also showed a high degree of homology with those of the major teleost β-actins and warm-blooded vertebrate β-cytoskeletal actins, suggesting their more recent common origin.

Effect of Dietary Protein and Lipid Levels on the Growth and Body Composition of Juvenile Long Snout Bullhead Leiocassis longirostris Gunther

We ran a feeding trial to determine optimal dietary protein and lipid levels for growth of juvenile long snout bullhead Leiocassis longirostris Gunther. Eight experimental diets (P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% or 50% protein combined with either 7% or 14% lipid. Three replicate groups of fish (mean mass: 3.9 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than that of fish fed the P40L14, P50L7 and P50L14 diets. Growth of fish fed diets containing 7% lipid increased with increasing protein level (up to 50% protein); growth of fish fed diets containing 14% lipid increased with increasing protein level (up to 30% protein). The feed efficiency of fish fed a diet with 50% protein and 7% lipid was higher than that of other groups. Whole body moisture and lipid contents were affected by dietary lipid level but not by dietary protein level. The crude lipid contents of fish fed 14% lipid diets were higher than those fed 7% lipid diets across all protein levels (other than the 50% level). Thus, under our experimental conditions, an increase in dietary protein level improved growth and feed efficiency of fish; a diet containing 50% protein with 7% lipid was optimal for growth and effective feed utilization in juvenile long snout bullhead.

Optimal Dietary Protein and Lipid Levels for Growth of Juvenile Muddy Loach Misgurnus anguillicaudatus

A feeding trial was conducted to determine the optimum dietary protein and lipid levels for the growth of juvenile muddy loach Misgurnus anguillicaudatus. Eight experimental diets (designated as P20L7, P20L14, P30L7, P30L14, P40L7, P40L14, P50L7 and P50L14) were formulated to contain 20%, 30%, 40% and 50% protein with 7% and 14% lipid. Three replicate groups of muddy loach (1.5 g/fish) were fed one of the experimental diets ad libitum for 8 weeks. Survival of fish fed the P20L14 diet was lower than in other groups (P