Isolation and characterization of bacteria causing mortality in early stage larvae of captive‐bred Japanese eels (Anguilla japonica Temminck & Schlegel)

Bacteria with lethal effect on eel larvae were isolated from moribund captive‐bred eel larvae and their 16S rRNA gene sequences were analysed. Nucleotide sequence of 10 isolates showed highest similarity with Lacinutrix algicola, Crocinitomix catalasitica and Pseudoalteromonas rubra. Age‐dependent changes in the susceptibility of eel larvae were observed in response to challenge by a highly lethal isolate. Compared with 10 and 11 days after hatching (DAH), larval susceptibility to the highly lethal isolate was lower at 18 DAH. We found that the bacterial isolates have lethal effect on the captive‐bred eel larvae, especially at the early developmental stage. These results will be useful to establish appropriate culture practices for eel larvae that will improve the success of mass production of glass eels for aquaculture.     

Anesthesia,fasting tolerance,and nutrient requirement of juvenile northern bluefin tuna

ABSTRACT:   The present study aimed to investigate a suitable anesthesia protocol for nutritional studies, fasting tolerance, and nutrient requirements for maintenance in juvenile northern bluefin tuna Thunnus orientalis weighing 0.8–0.9 g. The fish grew in a mass seedling production under completely controlled aquaculture. The solution of 0.2 mL 2-phenoxyethanol/L prepared by filtered seawater has been notably estimated as a anesthesia protocol for the juvenile, due to a shorter mean time necessary for anesthesia and recovery and higher survival rate at 24 h after recovery. All other anesthetics, 0.1 and 0.3 mL 2-phenoxyethanol/L, 0.05, 0.1 and 0.2 mL 4-allyl-2-methoxyphenol/L, and cool water temperature shocks at 16.8, 12.6 and 10.4°C, were inferior. In a 5-day tolerance test, the juvenile was fed sand lance Ammodytes personatus through the rearing period or fasted for 2, 3, 4 and 5 consecutive days. Survival rates were about 80 or 60, 50, 10 and 0%, respectively. From the relationships between days fasting and energetic and nutritional retentions, juvenile tuna require about 142.7 kJ, 5.46 g protein and 0.44 g fat/kg body weight a day for maintenance, indicating remarkably higher requirements than other aquaculture fish.     

Fatty acid composition in sea cucumber Apostichopus japonicus fed with microbially degraded dietary sources

Fatty acids (FAs) in the body walls of sea cucumber, Apostichopus japonicus, reared under diet‐administered conditions were analysed to determine the accumulative status of dietary FAs. Four test diets different in diet source and microbial degradation, that is, a diet composed of powdered pennate diatoms (diet PD), one microbially degraded of diet PD (diet PDM), one composed of brown algae [tangle weed, Saccharina (Laminaria) longissima (Miyabe); diet BA], and one microbially degraded of diet BA (diet BAM), were fed to juvenile A. japonicus, respectively, for 2 months and the FA composition of the juvenile body wall was determined. FAs in body wall were influenced and changed by diet source and microbial degradation of diet. Degradation significantly promoted juvenile's growth and increased iso‐15:0 in the body wall; however, iso‐15:0 was not a growth factor. FA 20:4n6 and 20:5n3 were dominant in all groups despite being a minor dietary constituent, suggesting that these FAs can be readily accumulated or synthesized in the animal.     

Efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in yearling red sea bream Pagrus major fed low-fishmeal diet

ABSTRACT:   This study was performed to evaluate the efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in red sea bream Pagrus major fed a low-fishmeal (FM) diet. Yearling red sea bream were fed for 34 weeks on low-FM diets either supplemented with taurine, or without taurine, and the tissue taurine and bile pigment concentrations were measured. Compared to the fish fed the FM diet, fish fed the low-FM diet without taurine supplementation resulted in inferior feed performances and higher incidence of green liver related to the morphological transformation of the erythrocytes. In these fish, the hepatopancreatic taurine concentration was significantly lower and hepatopancreatic biliverdin concentration was high compared to the fish fed the FM diet. These parameters were markedly improved by taurine supplementation of the low-FM diet and were similar in levels to the fish fed the FM diet. These results indicate that green liver appearance and inferior feed performances of red sea bream fed the low-FM diet without taurine supplementation were caused by dietary taurine deficiency, and indicate the requirement of taurine supplementation to low-FM diets for red sea bream.     

Role of nitric oxide in hemodialysis-related hypotension in an experimental renal dysfunction dog model

To clarify the role of nitric oxide (NO) in hemodialysis (HD)-related hypotension, the relationship between plasma NO metabolites (NOx) and blood pressure changes, and the effect of N(G)-monomethyl-L-arginine (L-NMMA), a NO synthase inhibitor, on changes in blood pressure were evaluated in an experimental renal dysfunctional dog model. In order to create a renal dysfunction model, gentamicin was administered to male beagles in which 7 of 8 renal artery branches had been ligated. Normal renal functional and dysfunctional dogs underwent 3 hr of HD per day for 3 days. HD induced a transient decrease in mean blood pressure in the normal renal functional dogs. In renal dysfunctional dogs, a continuous hypotension occurred with a gradual increase in the plasma NOx concentration during HD. Although L-NMMA prevented the fall in blood pressure, it did not significantly change the plasma NOx concentration during HD. These results suggest that NO contributes to HD-related hypotension in renal dysfunctional dogs but the plasma NOx concentration does not reflect the change in blood pressure.     

Molecular phylogeographic analyses and species delimitations reveal that Leopoldamys edwardsi (Rodentia: Muridae) is a species complex

Leopoldamys edwardsi is a species with wide distribution ranges in southern China but is not discussed in studies on geographic variation and species differentiation. We used 2 mitochondrial (Cytb, CO1) and 3 nuclear (GHR, IRBP and RAG1) genes to clarify species phylogeography and geographical differentiation. Maximum likelihood (ML) and Bayesian phylogenetic inference (BI) trees consistently indicated that L. edwardsi is a species complex containing 3 main lineages with high Kimura‐2‐parameter (K2P) divergences (i.e. lineages L_N, L_S and L_HN) found in the northern and southern China and Hainan Island, respectively. The 3 species delimitation methods, automated barcoding gap discovery, Bayesian poisson tree process analysis and Bayesian phylogenetics and phylogeography, consistently supported the existence of cryptic species. Divergence times among the main lineages were inferred to be during the Pleistocene, with L_HN/L_S split at 1.33 Ma and L_N/(L_HN+L_S) at 2.61 Ma; the diversifications of L. edwardsi complex might be caused by the rapid uplifts of Tibetan Plateau, paleoclimate change and complex topography. The divergence between L_HN and L_S was probably related to the separation of Hainan Island from the mainland via the formation of the Qiongzhou Strait. Lineages L_N and (L_S+L_HN) likely diverged due to the Wuyi‐Nanling mountain range forming a dispersal barrier. Our results suggested that L. edwardsi complex contains at least 3 distinct species: L_HN represents L. hainanensis, endemic to Hainan Island and previously considered as a subspecies L. e. hainanensis; L_S represents a cryptic species distributed throughout the southern Chinese continent; and L_N represents the nominotypical species L. edwardsi.     

Phylogenetic characterization of Isospora jaracimrmani oocysts from a veiled chameleon (family Chamaeleonidae; Chamaeleo calyptratus) reared at a zoo in Ishikawa,Japan

Oocysts of Isospora sp. were detected in the feces of a veiled chameleon (family Chamaeleonidae; Chamaeleo calyptratus) kept at a zoo in Ishikawa, Japan. Phylogenetic analysis placed the sequence in the cluster of Isospora spp. isolated from reptiles. Based on a comparison of morphological data of ten previously reported Isospora species from the Chamaeleonidae family, this isolate was morphologically similar to I. jaracimrmani, which has been considered to be a virulent species. This case study suggests the possibility that species of Isospora might not always cause disease because the animal that shed these oocysts showed no symptoms for more than two months.     

Structure of Lysophosphatidylglyceryl-Remazolbrilliant Blue (LPG-RBB) from the Surface of Dyed Wheat Starch Granules

Wheat starch granule surface was covalently stained with Remazolbrilliant blue-R dye (RBB) and then extracted with 1% SDS containing 1% 2-mercaptoethanol (2-ME) at room temperature for 14.5 hr. The extracted blue-staining material (A₆₅₀) separated into two fractions. Low molecular weight (LMW) material was further purified by Sephadex G-75 size-exclusion chromatography and thin-layer chromatography. Infrared and nuclear magnetic resonance (¹H-NMR and ¹³C-NMR) spectroscopy indicated that the structure of the purified LMW material was 18-O-(6-lysophosphatidylglyceryl)-RBB.     

Moisture Distribution and Diffusion in Cooked Spaghetti Studied by NMR Imaging and Diffusion Model

Moisture diffusion in spaghetti during boiling and holding after boiling was analyzed with a cylinder diffusion model based on moisture content mapped by magnetic resonance imaging. The images showed water penetrating concentrically in the cross section of a cooked spaghetti strand. The moisture profiles calculated from the images refracted near the central part in undercooked spaghetti due to the presence of ungelatinized starch. The moisture profiles of the samples with different holding times intersected around one‐third of the radius from the surface. The slope of the moisture profile decreased along with the holding time while the moisture content at the intersection remained unchanged. The diffusion coefficients were determined statistically for the fully gelatinized region with a cylinder model. The theoretical moisture profiles calculated using such coefficients fitted very well to experimental data. The diffusion coefficients of dried spaghetti were smaller than those of fresh spaghetti at both boiling and holding periods, suggesting that the moisture transport property had been reduced by the drying process during manufacture of spaghetti. The diffusion coefficients decreased with increases in boiling and holding times. The diffusion model with a constant diffusion coefficient is, therefore, valid in a limited boiling or holding time.     

A microfluidic device for conducting gas-liquid-solid hydrogenation reactions

We have developed an efficient system for triphase reactions using a microchannel reactor. Using this system, we conducted hydrogenation reactions that proceeded smoothly to afford the desired products quantitatively within 2 minutes for a variety of substrates. The system could also be applied to deprotection reactions. We could achieve an effective interaction between hydrogen, substrates, and a palladium catalyst using extremely large interfacial areas and the short path required for molecular diffusion in the very narrow channel space. This concept could be extended to other multiphase reactions that use gas-phase reagents such as oxygen and carbon dioxide.