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.     

Effect of ovarian hormones on maturation of dendritic cells from peripheral blood monocytes in dogs

Previously, we reported that ovarian hormones affect the immune response against E. coli isolated from the dogs affected with pyometra. In order to investigate mechanisms underlying the immune modulation, we examined the effects of ovarian hormones on the generation of dendritic cells (DCs), the most potent antigen presenting cell. DCs were differentiated from peripheral blood monocytes (PBMOs) using a cytokine cocktail. Both estrogen receptor and progesterone receptors were expressed by the PBMOs and immature DCs. When various ovarian hormones were added to the culture for the DC differentiation, progesterone significantly decreased the expression of DC maturation markers, such as CD1a, CD80 and CD86, on mature DCs. Conversely, the addition of estrogen to the cultures increased the expression of CD86, but not other maturation makers. Furthermore, DCs differentiated in the presence of progesterone did not stimulate allogeneic mononuclear cells in PB. Taken together, these results indicate that progesterone diminishes the maturation of DCs, leading to decreased immune responses against invading pathogens.     

Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations

Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.     

Detecting endotoxin activity in bovine serum using an automated testing system

The aim of the present study was to compare the ability of the commercially available portable test system (PTS^TM) to detect endotoxin activity in bovine serum, with that of the traditional LAL-kinetic turbidimetric (KT) and chromogenic (KC) assays. Prior to testing, serum samples, which were obtained from endotoxin-challenged cattle, were diluted 1:20 in endotoxin-free water and heated to 80°C for 10 min. The performance of the PTS^TM was not significantly different from that of the traditional LAL-based assays. The results using PTS^TM correlated with those using KT (r²=0.963, P<0.001) or KC assays (r²=0.982, P<0.001). Based on these findings, the PTS^TM could be applied as a simplified system to assess endotoxin activity in bovine serum.     

Mangrove Habitat Formation and Response to Holocene Sea-level Changes on Kosrae Island,Micronesia

Mangrove habitats on Kosrae are divided into three types, i.e., an estuary or delta type, a backmarsh or lagoon type and a coral reef or tidal-flat type. Most of the mangrove forests of Kosrae have been developed during the last 2000 years by accumulating mangrove peat with the gradual sea-level rise of 1 to 2 mm/yr except the landward part of the estuary or delta type. On the other hand, during the period of rapid sea-level rise of about 10 mm/yr between 4100 and 3700 yr B.P., the mangrove forests ceased peat accumulation and retreated landward. Until 3500 yr B.P., mangrove forests were distributed only in narrow bands in the inlets. Therefore, the critical rate of mangrove peat accretion with sea-level rise is estimated at more than 2 mm/yr and less than 10 mm/yr. If the anticipated sea-level rise exceeds this critical rate, all of the mangrove forests of Kosrae will retreat landward and reduce rapidly.     

Energy and carbon dioxide (CO2) balance of logging residues as alternative energy resources: system analysis based on the method of a life cycle inventory (LCI) analysis

Using the method of a life cycle inventory (LCI) analysis, the energy balance and the carbon dioxide (CO₂) emission of logging residues from Japanese conventional forestry as alternative energy resources were analyzed over the entire life cycle of the residues. The fuel consumption for forestry machines was measured in field experiments for harvesting and transporting logging residues at forestry operating sites in Japan. In addition, a total audit of energy consumption was undertaken. It involved an assessment of materials, construction, and the repair and maintenance of forestry machines as well as the costs associated with an energy-conversion plant. As a result, the ratio of energy output to input was calculated to be 5.69, indicating that the system examined in this study could be feasible as an energy production system. The CO₂ emission per MWh_e (e: electricity) of the biomass-fired power generation plant was calculated to be 61.8kgCO₂/MWh_e, while that of coal-fired power generation plants in Japan is 960kgCO₂/MWh_e. Therefore, the reduction in the amount of CO₂ emission that would result from replacing coal with biomass for power generation by as much as 3.0 million dry-t/year of logging residues in Japan was estimated to be 1.66 million tCO₂/year, corresponding to 0.142% of the national CO₂ emission. This study provides evidence that Japan could reduce its domestic CO₂ emission by using logging residues as alternative energy resources.     

Co-transmission of <Emphasis Type="Italic">Tomato yellow leaf curl virus</Emphasis> (TYLCV)-Mld and TYLCV-IL by the whitefly <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

The ability of the whitefly Bemisia tabaci to transmit two strains of Tomato yellow leaf curl virus, the Israel and Mild strains, was studied after serial transfers of individual whiteflies that were viruliferous for both strains to tomato plants. After single whiteflies had successive acquisition feedings first on a single plant infected with one strain and then on a plant infected with the other strain, the single whiteflies later transmitted intermittently one, the other, or both strains to the test plants during serial transfers at 1-day intervals. Because both strains were found in the head, abdomen, and legs dissected from whiteflies during the retention period after the two successive acquisition feedings, both strains apparently circulate from midgut cells to salivary glands through the hemolymph.     

Formation mechanism of p-methylacetophenone from citral via a tert-alkoxy radical intermediate

The aim of this study was to clarify the formation mechanism of a potent off-odorant, p-methylacetophenone, from citral under acidic aqueous conditions. An acidic aqueous solution (pH 3.0) containing 10 mg/L of citral was stored at 40 degrees C for 2 weeks. Among the compounds detected in the stored citral solution, 4-(2-hydroxy-2-propyl)benzaldehyde was identified for the first time as a degradation product from citral. The formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde behaved the same when antioxidants were added to the citral solution. In addition, both compounds were formed by the Fe(2+)-induced decomposition of 8-hydroperoxy-p-cymene, another compound identified in the stored citral solution. These results suggested that both p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde can be formed via the same radical intermediate [p-CH3C6H4C(CH3)2O*] that can be derived from the O-O bond homolysis of 8-hydroperoxy-p-cymene. On the other hand, the degradation of 8-hydroperoxy-p-cymene without Fe2+ under acidic aqueous conditions did not yield p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde, but the degradation of citral without Fe2+ did. Therefore, other than the decomposition of 8-hydroperoxy-p-cymene, a mechanism to generate the tert-alkoxy radical intermediate was proposed for the formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde in the citral solution.     

Antiallergic tea catechin, (-)-epigallocatechin-3-O-(3-O-methyl)-gallate,suppresses FcepsilonRI expression in human basophilic KU812 cells

We previously found that the O-methylated derivative of (-)-epigallocatechin-3-O-gallate (EGCg), (-)-epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG' '3Me), has potent antiallergic activity. The high-affinity IgE receptor, FcepsilonRI, is found at high levels on basophils and mast cells and plays a key role in a series of acute and chronic human allergic reactions. To understand the mechanism of action for the antiallergic EGCG' '3Me, the effect of EGCG' '3Me on the cell surface expression of FcepsilonRI in human basophilic KU812 cells was examined. Flow cytometric analysis showed that EGCG' '3Me was able to decrease the cell surface expression of FcepsilonRI. Moreover, immunoblot analysis revealed that total cellular expression of the FcepsilonRI alpha chain decreased upon treatment with EGCG' '3Me. FcepsilonRI is a tetrameric structure comprising one alpha chain, one beta chain, and two gamma chains. The level of mRNA production of each subunit in KU812 cells was investigated. EGCG' '3Me reduced FcepsilonRI alpha and gamma mRNA levels. The cross-linkage of FcepsilonRI causes the activation of basophils, which leads to the secretion of inflammatory mediators including histamine. EGCG' '3Me treatment inhibited the FcepsilonRI cross-linking-induced histamine release. These results suggested that EGCG' '3Me can negatively regulate basophil activation through the suppression of FcepsilonRI expression.