Status of giant clam resources around Okinawa‐jima Island,Ryukyu Archipelago,Japan

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Effect of fishmeal substitution with various animal and/or plant protein sources in the diet of the abalone Haliotis discus hannai Ino

The effect of dietary substitution of animal and/or plant protein sources for fishmeal on the growth and body composition of juvenile abalone was determined. Nine experimental diets in triplicate were prepared: Con, SM, PM, CM, SPM, MB, SM+CM, SM+SPM and CM+SPM diets. A 350 g kg^?1 fishmeal was included in the Con diet, and the whole fishmeal was substituted with a 580 g kg^?1 soybean meal (SM), 335 g kg^?1 poultry meal (PM), 370 g kg^?1 corn gluten meal (CM), 325 g kg^?1 silkworm pupae meal dehydrated (SPM), 590 g kg^?1 meat and bone meal (MB), the combined 290 g kg^?1 soybean meal and 180 g kg^?1 corn gluten meal (SM+CM), 290 g kg^?1 soybean meal and 160 g kg^?1 silkworm pupae meal dehydrated (SM+SPM) and 180 g kg^?1 corn gluten meal and 170 g kg^?1 silkworm pupae meal dehydrated (CM+SPM) diets respectively. All experimental diets were iso‐nitronic and iso‐lipidic. The survival of abalone fed with the SM and SM+SPM diets was higher than that of abalone fed with the CM, SPM, MB and CM+SPM diets. Weight gain of abalone fed with the SM+SPM diet was higher than that of abalone fed with all the other experimental diets, except for that of abalone fed with the SM+CM diet. The combined soybean meal and corn gluten meal (SM+CM) or silkworm pupae meal (SM+SPM) could be replaced with the whole fishmeal in the diet for abalone and improved its performance.     

Compensatory growth and body composition of juvenile black rockfish <Emphasis Type="Italic">Sebastes schlegeli</Emphasis> following feed deprivation

ABSTRACT:   Compensatory growth, feeding rate, feed efficiency and chemical composition of juvenile black rockfish (mean weight 1.43 g) were investigated for 35 days after a 14-day feed deprivation treatment under four feeding conditions: one group continuously fed (control) and the other three groups fasted for 5 days (F5), 10 days (F10) and 14 days (F14). All fasted fish were re-fed from day 15. Only F5 achieved the same body weight as the control, indicating that complete compensation occurred in F5. The specific growth rate (SGR) of F5 was the highest at day 21 and then decreased thereafter, showing higher values than the control at days 21, 28 and 42. In contrast, although SGRs of F10 and F14 were higher than that of the control during the whole refeeding period except day 21, they did not catch up the control in body mass, indicating that only partial compensation occurred in F10 and F14. The feeding rate (FR) of all groups except F14 changed in a pattern similar to SGR (Spearman's rank correlation, r _s > 0.9), suggesting that SGR varied depending on FR. Similar feeding efficiencies (FEs) were found in the four groups and they did not vary significantly during the whole refeeding period, suggesting that FE was not the factor affecting SGR. At day 14, the ratios of lipid to lean body mass in F10 and F14 were lower than those in the control and F5, and there was no difference between the control and F5. At day 49, however, only F14 showed a lower value than the other three groups, and there was no difference among the three groups. These results indicate that juvenile black rockfish fasted for 5–14 days can exhibit compensatory growth after refeeding, but timing and degree vary depending on the duration of feed deprivation.     

Effect of thermal stress on Hsp70 gene expression and female reproductive performance of giant freshwater prawn,Macrobrachium rosenbergii

Using Hsp70 as a biomarker, thermal stress impinges on reproductive organs, ovary and hepatopancreas were being analyzed by determining the expression of Hsp70 mRNA inside the organs after the adult inter‐molt females were subjected to thermal treatment at 35, 30 and 28°C (Control). Results showed the expression of Hsp70 mRNA under thermal treatment of 35°C after 2 hr recovery in ovary were upregulated at 2, 4, 6, 12, 24 hr and 30 days compared to control whereas in hepatopancreas under similar treatment, the expression of Hsp70 mRNA were significantly higher than control at 6, 24 hr and 30 days. Frequency of reproductive molt at 35°C showed the ovary of females were failed to develop and only entered common molt along three consecutive molt cycles. For 30°C thermal treatment, the expression of Hsp70 mRNA was significantly higher than control after 2 hr recovery but returned to normal afterwards until 30 days’ thermal treatment. Maternal heat shock for 2 hr at 35°C were found to give significantly lower frequency of reproductive molt and longer duration of ovarian development and incubation period whereas maternal heat shock for 2 hr at 30°C gave lower frequency of reproductive molt, slower development of embryo and lower hatching success compared to untreated control. This study suggests that short and long‐term thermal stress at 30 and 35°C were found to affect the induction of Hsp70 mRNA in reproductive organs of Macrobrachium rosenbergii and also influence their reproductive performance.     

Association between the body weight of growing pigs and the functional capacity of their gut microbiota

Gastrointestinal microbiota impact host's biological activities, including digestion of indigestible feed components, energy harvest, and immunity. In this study, fecal microbiota of high body weight (HW) and low body weight (LW) growing pigs at 103 days of age were compared. Principal coordinates analysis separated the HW and LW groups into two clusters, indicating their potential differences between microbial community composition. Although the abundances of two major phyla, Firmicutes and Bacteroidetes, did not significantly differ between the HW and LW groups, some genera showed significant differences. Among them, Peptococcus and Eubacterium exhibited strong positive correlations with body weight (BW) and average daily gain (ADG) (Rho > 0.40), whereas Treponema, Desulfovibrio, Parabacteroides, and Ruminococcaceae_unclassified exhibited strong negative correlations with BW and ADG (Rho < ?0.40). Based on these results, the structure of intestinal microbiota may affect growth traits in pigs through host–microbe interactions. Further in‐depth studies will provide insights into how best to reshape host–microbe interactions in pigs and other animals as well.     

Identification of Vibrio harveyi,Vibrio ichthyoenteri,and Photobacterium damselae isolated from olive flounder Paralichthys olivaceus in Korea by multiplex PCR developed using the rpoB gene

Major fish bacterial diseases in Korea are edwardsiellosis, streptococcosis, and vibriosis. Among vibrionaceae, Listonella anguillarum, Vibrio harveyi, V. ichthyoenteri, and Photobacterium damselae were identified as causative organisms of vibriosis in flounder. In this study, we developed a multiplex PCR method using the RNA polymerase β subunit (rpoB) gene, known as a housekeeping gene for identification of Vibrio spp. causing vibriosis in flounder. Three pairs of PCR primers were designed based on the rpoB sequence of three species, V. harveyi, V. ichthyoenteri, and P. damselae. The PCR assay, using a mixture of six primers, yielded amplicons of 601, 434, and 533 bp in V. harveyi, V. ichthyoenteri, and P. damselae. None of the untargeted species yielded an amplicon. The detection limits for pure culture in kidney were 2.5 × 10⁴ cfu/g kidney for V. harveyi, 2.5 × 10⁵ cfu/g kidney for V. ichthyoenteri, and 2.5 × 10⁶ cfu/g kidney for P. damselae. From the colonies on TCBS agar plates of different samples, 632 Vibrio spp. isolated from aquacultured flounder between 2004 and 2010 were identified by the multiplex PCR method. As a result, 265 strains (41.9 %) were V. ichthyoenteri; 115 strains (18.2 %) were V. harveyi and 72 strains (11.4 %) were P. damselae.     

Edwardsiella tarda infection in Korean catfish,Silurus asotus,in a Korean fish farm

Mass mortality of Korean catfish, Silurus asotus, occurred in a culture farm situated in Jeollabukdo Province, Korea. The cumulative mortality rates reached up to 5% of the total fish in the farm per day. In clinical signs, the affected fish showed abdominal distension, vent protrusion, enteritis, liver congestion and abscess‐like lesions in enlarged spleen and kidney. Histopathologically, in the liver, hepatocytes lost fat and underwent atrophy or necrosis. The spleen showed necrotized splenocytes and a haemorrhagic pulp. In the kidney, glomerular destruction, degeneration of renal tubular epithelial cell and haemorrhage were observed. However, necrotic muscular lesions were not observed. A pure bacterial isolate was obtained from the liver, spleen and kidney lesions of affected fish. Experimental infection of normal catfish with the isolate resulted in the development of clinical signs similar to those seen on the farm. The isolates were identified as Edwardsiella tarda through biochemical tests (99.4%) and analysis of bacterial genes (16S rDNA) sequences (98%). The bacteria possessed two virulent genes: sodB and katB genes. These results suggest that E. tarda can act as a pathogen of farmed catfish. This is the first report showing that E. tarda caused mortality in cultured Korean catfish.     

Purification and characterization of cysteine proteinase inhibitors from crucian carp <Emphasis Type="Italic">Carassius auratus</Emphasis> eggs

Two cystatins (cst-I and cst-II) were purified from crucian carp eggs by acidification and subsequent ion exchange and molecular sieve chromatography. The molecular masses of cst-I and cst-II analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis were 11.9 and 14.4 kDa, respectively, under reducing conditions and 13.5 and 12.7 kDa, respectively, under non-reducing conditions. The cst-I and cst-II molecules were stable after 30 min of incubation at 60 and 50°C, respectively. There was no significant loss in the inhibitory activity of either cst in the pH range 4–11. These two cystatins were able to affect the proteolysis of papain, cathepsin L, and bromelain, but they were unable to inhibit cathepsin B and trypsin. The partial N-terminal amino acid sequences of both cst inhibitors were homologous and that of cst-I was recognized as NH₂-AGIPGGLVDADINDADVQ. This latter fragment shared 88.9% identity to common carp cystatin and 44.4–55.6% to cystatins of other aquatic animals. Based on these results, we conclude that the two cst inhibitors are members of family II cystatin.     

Aroma finishing of PET fabrics with PVAc nanoparticles containing lavender oil

A durable aroma finishing for PET fabric was carried out by adopting poly(vinyl acetate) (PVAc) nanoparticles containing lavender oil (LO) in core. Relatively small size of PVAc nanoparticles (ca. 244 nm of mean particle diameter) was expected to resist the frictional destruction of the particles, which is frequently observed in cases of microcapsules. PVAc nanoparticles containing LO in core were prepared by emulsification-diffusion method and their application as an aroma releasing agent for PET fabrics was assessed through the observation of releasing profiles of LO in ethanol for experimental acceleration. Melamine-formaldehyde (MF) microcapsules containing LO were also prepared and treated on fabrics for comparison. PVAc nanoparticles treated on PET fabric showed higher initial releasing amount, which was ascribed to the enhanced surface area. After 2 days of releasing, PET fabric treated with PVAc nanoparticles showed slower and more stable releasing profile and reached about 12 ppm of cumulative release after 16 days, which was under two thirds of that with MF microcapsules. PVAc nanoparticles can be used as an agent for durable aroma finishing of PET fabrics.