Characterization of Aquimarina hainanensis isolated from diseased mud crab Scylla serrata larvae in a hatchery

Mass mortality due to necrosis signs occurred in hatchery-reared zoea stage larvae of the mud crab Scylla serrata in Okinawa, Japan, and a causative bacterium was isolated. In this study, we identified and characterized the bacterium by genome analysis, biochemical properties and pathogenicity. The bacterium was a Gram-negative, non-motile, long rod, forming yellow colonies on a marine agar plate. It grew at 20–33°C (not at 37°C) and degraded chitin and gelatin. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Aquimarina hainanensis. Genome sequence data obtained from Illumina MiSeq generated 29 contigs with 3.56 Mbp in total length and a G + C content of 32.5%. The predicted 16 chitinase genes, as putative virulence factors, had certain homologies with those of genus Aquimarina. Experimental infection with the bacterium conducted on larvae of four crustacean species, brine shrimp Artemia franciscana, freshwater shrimp Caridina multidentata, swimming crab Portunus trituberculatus and mud crab S. serrata, revealed that this bacterium was highly virulent to these species. The present study suggests that the bacterium caused mass mortality in mud crab seed production was A. hainanensis and can be widely pathogenic to crustaceans.     

Analysis of Phytosterol,Fatty Acid,and Carotenoid Composition of 19 Microalgae and 6 Bivalve Species

ABSTRACT

In this study, the functional components of 19 microalgae and 6 bivalve species were investigated in the context of the application in bivalve feeding and human health food. Principal component analysis was performed to detect any association between the functional components and individual microalgal species or taxonomic group. The proportions of the functional components differed depending on the taxonomic group or species of microalga. The genera Cheatoceros, Thalassiosira, and Isochrysis contained high concentrations of fucosterol and fucoxanthin, which are present in large amounts in brown algae. Diatoms, haptophytes, and eustigmatophytes, which are used as feed for bivalves, were rich in fucosterol and eicosapentenoic acid (EPA); further, haptophytes were rich in docosahexaenoic acid (DHA). In addition, the microalgae associated with red tide, i.e., the raphidophytes, were found to be rich in fucoxanthin, β-sitosterol, and EPA, whereas dinoflagellates were rich in DHA. Seven bivalve species also contained high concentrations of fucosterol, EPA, and DHA, as did microalgae, which were used to feed by bivalves. These results are useful in selecting microalgae effectively as feed of the bivalves.     

α-Melanocyte-stimulating hormone directly increases the plasma calcitonin level and involves calcium metabolism in goldfish

International Aquatic Research - The effects of α-melanocyte-stimulating hormone (α-MSH) on calcium metabolism were examined with goldfish. The scales on the left side of goldfish bodies...     

Photoautotrophic cultivation of oleaginous microalgae and co-pelletization with filamentous fungi for cost-effective harvesting process and improved lipid yield

Oleaginous microalga Scenedesmus obliquus SIT06 was selected as potential biodiesel feedstocks due to its high lipid content and suitable fatty acid composition for production of biodiesel with high oxidative stability and high cetane number. The important factors for cultivating microalgae in photoautotrophic mode were optimized through response surface methodology (RSM). The highest microalgal biomass obtained was 1.99?±?0.12 g L^?1 with a high lipid content of 40.86?±?0.32%. To simplify harvesting process of microalgal cells, pellet-forming filamentous fungi were inoculated into the late log-phase of microalgae culture. Among the fungi tested, Cunninghamella echinulata TPU 4652 most effectively harvested the microalgal cells with the highest flocculation efficiency of 92.7%. Moreover, the biomass and lipids of microalgae-fungi pellets were as high as 4.45?±?0.06 and 1.21?±?0.08 g L^?1, respectively. The extracted lipids were mainly composed of C16:0, C18:0, and C18:1, and their estimated fuel properties meet with the international standards indicating their potential use as biodiesel feedstocks. This study has shown the strategies not only to simplify the harvesting process but also to increase the lipid yield and tailor the lipid composition.     

The locus for resistance to Asian soybean rust in PI 587855

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is one of the most serious soybean (Glycine max) diseases in tropical and subtropical areas. A soybean line, PI 587855, showed a resistance phenotype against ASR pathogens in Japan and South America at high frequency; however, little is known of the genetic control of this resistance and chromosomal location of the corresponding locus. Therefore, the aim of this study was to study the inheritance of PI 587855 resistance and map the corresponding locus with SSR markers aiming to use the linked markers in marker‐assisted selection. In the segregating population, resistance to ASR appeared to be controlled by a single dominant gene. The ASR resistance locus was mapped near to the chromosomal region where the resistant loci, Rpp1 and Rpp1‐b, were previously mapped. Comparative genetic mapping and disease reaction profiles of other seven lines carrying Rpp1 or Rpp1‐b to four Brazilian ASR isolates revealed that the resistance reaction exhibited by PI 587855 was similar to that of Rpp1‐b‐carrying varieties which have useful resistance to South American ASR strains.     

Field measurement of infiltration rate using an oscillating nozzle rainfall simulator in the cold, semiarid grassland of Mongolia

Recent intensive grazing in Mongolia may be significantly reducing the infiltration rate of rangeland. This study measured infiltration rates using simulated rainfall with high raindrop impact for small plots established on steppe grassland, desert grassland, and shrubland sites in Mongolia. The response of the infiltration rate to short-term livestock removal was also investigated. On the steppe grassland, a high infiltration rate was measured on an ungrazed plot with relatively dense vegetation cover; a statistically significant correlation was found between the total surface cover and final infiltration rate, indicating that surface cover by rock fragments also increased the infiltration rate to some extent. For desert grassland and shrubland, however, the surface cover condition was not a major factor controlling the final infiltration rate. After 4 years of livestock removal, the surface vegetation cover of the ungrazed plot was greater than that of the grazed plot, but no appreciable change occurred in soil penetration resistance. These results suggest that the high infiltration rate on the ungrazed plot was maintained mainly by the recovery of surface vegetation cover after the short-term livestock removal; this may indicate a potential mechanism of recovery from desertification processes for Mongolian rangeland.     

Emphysematous cystitis in a chemically-induced diabetic dog

Emphysematous cystitis is a rare disorder caused by bacterial infection and characterized by gas accumulation within the bladder wall with cyst formation. This report describes the histopathological characteristics of emphysematous cystitis found in a diabetic female beagle induced by streptozotocin and alloxan. Macroscopically, multiple cyst-like structures were observed on the cut surface of the urinary mucosa. During fixation, small specimens cut from the mucosa floated on the surface of the fixative solution. Histopathologically, multiple cysts were lined with a single layer of flattened cells found to be immunohistochemically positive for vimentin, partially positive for α-smooth muscle actin or macrophage scavenger receptor, class A, and thought to be myofibroblasts, fibroblasts or macrophages. Multinucleated giant cells were observed around the cysts, and gram-negative short bacilli were observed in the lumen of the urinary bladder. From these findings, this case was diagnosed as emphysematous cystitis.