Culture method and growth characteristics of marine benthic dinoflagellate Ostreopsis spp. isolated from Japanese coastal waters

Blooms of toxic dinoflagellates of the genus Ostreopsis, which is known as a producer of palytoxin (PTX) analogs, may pose a threat to human health in tropical, subtropical, and temperate regions around the world. In the present study, we established a suitable culture method for Ostreopsis spp. isolated from Japanese coastal waters and characterized their growth potential using the method to discuss their bloom dynamics. Each clonal strain of Ostreopsis cf. ovata, Ostreopsis sp.?1, Ostreopsis sp.?5, and Ostreopsis sp.?6 was incubated in 25?×?150?mm test tubes with a flat bottom containing various kinds of medium. Since Ostreopsis spp. strains grew well in IMK and/or f/2 media, we selected these media for cultivation of all the Ostreopsis spp. isolates. Growth rates of O. cf. ovata (0.834?divisions/day), Ostreopsis sp.?1 (0.619?divisions/day), and Ostreopsis sp.?6 (1.04?divisions/day) that produce PTX analogs significantly differed (p?<?0.05) respectively and are clearly higher than those of other reported epiphytic dinoflagellate Gambierdiscus toxicus, Prorocentrum lima, and Coolia monotis cultures, which suggest that these species have ecological advantages to predominate through the algal succession in Japanese coastal waters, resulting in a potential risk to human health in this region.     

Daily growth rate model of Japanese anchovy larvae Engraulis japonicus in Hiuchi-nada Sea, central Seto Inland Sea

In the present study, we developed a larval anchovy growth model in relation to sea temperature and food availability via food consumption and metabolic process terms, based on biological data from previous laboratory experiments and field surveys from 2003 to 2006 in Hiuchi-nada Sea, central part of Seto Inland Sea, Japan. To investigate when food shortage for larval anchovy and then recruitment failure occur in Hiuchi-nada Sea, anchovy food requirements were estimated by using the growth model, and we compared the food requirement with anchovy food availability. We applied an estimation method for growth model parameters, Hewett?CJohnson p and Q ₁₀, by minimizing the sum of squares of difference between mass-specific growth rates estimated by the models and those by otolith growth analysis. Parameter p was 0.86, slightly higher than typical values, and Q ₁₀ was 2.11, close to the value used for the biological model of larval northern anchovy. Food shortage for anchovy larvae did not occur in Hiuchi-nada Sea, although it was indicated that low food availability led to a low reproductive success rate. The newly developed growth model is considered optimal at present and useful to link environmental conditions and larval growth.     

Application of supercooling to long-term storage of fish meat

Fish meat was brought to a supercooled state through slow cooling, and changes in the texture, histology, and protein composition of the meat were investigated. The groups whose storage temperature were lowered by 1.0°C per day (the 1.0°C group) and 0.5°C per day (the 0.5°C group) began to freeze in the vicinity of −3.5 and −5.0°C, respectively. The freezing point depended on the fish species; the lowest freezing point was −8.5°C, for the red sea bream in the 1.0°C group. The breaking strength tended to decrease more slowly in the 1.0°C group, but the collagen fibers collapsed more rapidly in the 1.0°C group. In SDS electrophoresis, a slight change in the banding patterns was observed, but the relationship between this observation and changes in histology and physical properties was unclear. This study shows that it is possible to produce a supercooled state in fish meat, and demonstrates that supercooling is a potential new storage method that lowers the temperature without generating ice crystals.     

Effect of timing and type of supplementary grain on herbage intake,nitrogen utilization and milk production in dairy cows grazed on perennial ryegrass pasture from evening to morning

The present study aimed to clarify the effect of timing and type of supplementary grain in grazing dairy cows on herbage dry matter intake (HDMI), nitrogen utilization and milk production. Eight lactating cows were allowed to graze from evening to morning during three seasonal periods (spring, summer, autumn). They were randomly allocated to four treatments (timing: pre‐ (Pre) or post‐grazing (Post), for large grain allotments consisting of 75% of daily grain offered; grain type: barley or corn) in 4 × 4 Latin square designs in each period. In the spring period, HDMI was greater for cows fed corn than those fed barley (P = 0.005), whereas cows in the Pre treatment had a similar HDMI, higher (P = 0.049) urinary purine derivative concentration and greater (P = 0.004) milk yield compared with cows in the Post treatment. In the summer and autumn periods, timing treatments did not affect HDMI, nitrogen utilization or milk production, but cows supplemented with barley had higher urinary purine derivatives concentration (P < 0.05) and milk yield (P < 0.05) compared with those supplemented with corn. The results indicate that large grain allotments immediately before evening grazing during early grazing seasons increased ruminal microbial protein synthesis and milk production without reducing HDMI regardless of grain type.     

Characterization of the cathelicidin cluster in the Japanese quail (Coturnix japonica)

The Japanese quail has several advantages as a low‐fat meat bird with high immunity against diseases. Cathelicidins (CATHs) are antimicrobial peptides that play an important role in innate immunity. The aim of this study was to characterize the CATH cluster in the Japanese quail (Coturnix japonica). The Japanese quail CATH (CjCATH) cluster, contains four CATH genes, as in the chicken. The coding sequences of CjCATHs exhibited >85.3% identity to chicken CATHs. The predicted amino acid sequences of the four CjCATH genes contained the cathelin‐like domain characteristic of CATH proteins. Polymorphisms were detected in the open reading frames (ORFs) of all CjCATH sequences. Two amino acid substitutions were observed in the antimicrobial region of the mature peptide of CjCATH2, and predicted to influence peptide function. CjCATH1 is expressed in lung, heart, bone marrow and bursa of Fabricius (BF). CjCATH2 is expressed in bone marrow. CjCATH3 is expressed in lung, heart, bone marrow, BF, tongue and duodenum. CjCATHB1 is expressed in bone marrow and BF. This study is the first to characterize CATH genes in the Japanese quail, and identifies novel antimicrobial peptide sequences belonging to the cathelicidin family, which may play a role in immunity in this species.     

Improvement of preservation method for ammonia-oxidizing bacteria by freeze-drying

Long-term preservation of ammonia-oxidizing bacteria had been achieved until now by using the silica gel-freezing method. Recently, the freeze-drying method for the preservation of microorganisms has been widely used, and has been applied to the preservation of ammonia-oxidizing bacteria. The 10% skim milk-l% pyruvate or glutamate ratio was optimum as a dispersion-medium, and the preservation temperature of the freeze-dried cells was effective at -80°C. This method of preservation was found to be considerably more effective than the silica gel-freezing method.     

Relationship between the change in the chloroplastic nitrogen fractions and the rate of oxygen evolution in rice plants

Chloroplasts and the lamellae systems were isolated from rice leaves and the change with leaf age in the nitrogen fractions localized in the lamellae systems and the stroma region was examined. The pattern of the change in these two chloroplastic nitrogen fractions varied according to the leaf position. In order to find out the relationship between the change in the chloroplastic nitrogen fractions and the photosynthetic activity of a leaf, the rate of oxygen evolution of leaf sections on a total leaf nitrogen basia was also followed. The rate of oxygen evolution/total leaf nitrogen was affected by two factors. i.e., lamellae nitrogen/total leaf nitrogen and the lamellae-stroma composition of the chloroplast. An increase in lamellae nitrogen/total leaf nitrogen caused an increase in oxygen evolution, whereas an increaae in the proportion of stroma nitrogen in chloroplast brought about the negative effect. Consequently, oxygen evolution/total leaf nitrogen had a close correlation with an index of lamellae nitrogen²/total leaf nitrogen × chloroplast nitrogen. The relationship with the photosynthetic efficiency of the leaf nitrogen is also discussed.     

Quantitative loop-mediated isothermal amplification method for the detection of <Emphasis Type="Italic">Vibrio nigripulchritudo</Emphasis> in shrimp

Vibrio nigripulchritudo is considered one of the major pathogens threatening shrimp aquaculture. In this study, we developed a novel and highly specific quantitative loop-mediated isothermal amplification (Q-LAMP) assay. A set of four specific primers were designed targeting the V. nigripulchritudo intergenic spacer region. The reaction time and temperature were optimized for 60 min at 63°C. Quantitative analysis was then performed by measuring the turbidity of the reaction solution using a real-time turbidimeter, allowing for quantification of the initial DNA concentration with a sensitivity of 10² copy numbers equivalent to 2.3 colony forming units/ml or 0.3 fg/μl. The LAMP assay was able to specifically detect two representative strains of V. nigripulchritudo, whereas other Vibrio and non-Vibrio species were not amplified. A standard curve was generated for V. nigripulchritudo by plotting the threshold time (T _t) versus the log of bacterial number. A high correlation coefficient (R ² = 0.9749) was observed for the Q-LAMP reaction. In conclusion, Q-LAMP assay is a sensitive, rapid, and simple tool that can be used for the detection and quantification of V. nigripulchritudo in shrimp, thereby facilitating surveillance of vibriosis infection.     

Effect of dietary fish oil on enhanced inflammation and disturbed lipophagy in white adipose tissue caused by a high fat diet

Fisheries Science - Fish oil containing omega-3 polyunsaturated fatty acids (PUFA) attenuates chronic inflammation found in obesity, leading to a reduction in insulin resistance. The effect of fish...