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.     

Swim bladder inflation as a possible cause of saddleback-like syndrome malformation in hatchery-reared red spotted grouper <Emphasis Type="Italic">Epinephelus akaara</Emphasis>

Saddleback-like syndrome is one of the most frequently observed malformations in hatchery-reared red spotted grouper Epinephelus akaara. Saddleback-like syndrome is characterized by a V-shaped dorsal-profile depression behind the head region accompanied by deformities or misalignments of the first to fourth neural spines on the vertebral column and the first to fourth pterygiophores of the dorsal fin. Abnormal swim bladder inflation in several finfish species leads to malformations, particularly of the vertebral column. The present study examined the influence of swim bladder inflation on saddleback-like syndrome in hatchery-reared red spotted grouper. The incidence of saddleback-like syndrome increased as swim bladder inflation rate increased. Additionally, the incidence of saddleback-like syndrome among juveniles with inflated swim bladders was significantly higher than that among juveniles with uninflated swim bladders. The larval swim bladder is located just below the first to fifth vertebrae and the first to fifth dorsal spines, where saddleback-like syndrome occurs. Our results suggest that an inflated swim bladder increases the risk of saddleback-like syndrome in hatchery-reared red spotted grouper.     

A review of seed production and stock enhancement for commercially important portunid crabs in Japan

We reviewed the present status of seed production for stock enhancement and evaluated the impact of stocking on commercial catches in Japan, of portunid crabs particularly Portunus trituberculatus and Scylla paramamosain. The mean survival rate from hatching to first-stage crabs was around 10%, and 20–30% of the larval culture trials conducted in recent years could not harvest juveniles during seed production. To achieve reliable mass seed production technologies, measures for controlling disease and the nutritional condition of larvae in seed production tanks are required to be developed. The main spawning season extends from April/May to July. Reflecting their life cycle characteristics such as high growth rates, crabs recruit to the fishery after September and largely contribute to the commercial landings until December in the hatching year. The main release season of juveniles is from June to July. Consequently, released juveniles are expected to contribute to commercial landings in the release year. Analyses of catch and release statistics in two small bays estimated the yield from released individuals (YPR, yield per release) at 2.4 g for P. trituberculatus and 3.3–7.7 g for S. paramamosain, which were similar to values reported from tagging surveys. On a major regional basis, catch and release histories of P. trituberculatus highlighted the impact of hatchery releases on commercial landings as 33.6 g YPR in the Seto Inland Sea, where catches and releases have been greatest. Although the YPR estimates were different between small bays and major regional seas, Japanese stock enhancement programmes should have had an impact on portunid crab production, dependent on the magnitude of the releases.     

Analysis of hop-derived terpenoids in beer and evaluation of their behavior using the stir bar-sorptive extraction method with GC-MS

Hop aroma components, which mainly comprise terpenoids, contribute to the character of beers. However, pretreatments are necessary before analyzing these components because of their trace levels and complicated matrixes. Here, the stir bar-sorptive extraction (SBSE) method was used to detect and quantify many terpenoids simultaneously from small samples. This simple technique showed low coefficients of variation, high accuracy, and low detection limits. An investigation of the behavior of terpenoids identified two distinct patterns of decreasing concentration during wort boiling. The first, which was seen in myrcene and linalool, involved a rapid decrease that was best fitted by a quadratic curve. The second, which was observed in beta-eudesmol, humulene, humulene epoxide I, beta-farnesene, caryophyllene, and geraniol, involved a gentle linear decrease. Conversely, the concentration of beta-damascenone increased after boiling. As the aroma composition depended on the hop variety, we also examined the relationship between terpenoid content and sensory analysis in beer.     

Fishery biology of mud crabs <Emphasis Type="Italic">Scylla</Emphasis> spp. at Iriomote Island,Japan: species composition,catch, growth and size at sexual maturity

The fishery biology of mud crabs Scylla spp. was examined using baited traps and gill nets from September 2001 to August 2005 at Iriomote Island, Japan. To elucidate the growth of the crabs, artificially produced S. serrata juveniles were released and recaptured at the study site. The sizes at which 50% of females and males of S. serrata reached sexual maturity (SM₅₀) were estimated as an external carapace width (ECW) based on the morphology of the abdomen and the chela respectively. Two species, S. serrata and S. olivacea, were identified in the area with S. serrata being the dominant species (>95% of the catch). Changes in the mean ECW and the results of the release and recapture experiments suggested that the recruitment of young crabs to the fishery occurred from December/January to April/May. The SM₅₀ of females and males occurred at 132.4 and 150.7 mm ECW respectively. The body size composition of S. serrata revealed that immature crabs comprised approximately 40 and 65% of the catch for females and males respectively. To maintain a sustainable fishery for S. serrata, a minimum landing size based on the SM₅₀ estimates should be implemented as a fishing regulation.     

Survey of viruses infecting open‐field pepper crops in Côte d'Ivoire and diversity of Pepper veinal mottle virus and Cucumber mosaic virus

The prevalence of viruses in pepper crops grown in open fields in the different agro‐ecological zones (AEZs) of Côte d'Ivoire was surveyed. Pepper veinal mottle virus (PVMV; genus Potyvirus) and Cucumber mosaic virus (CMV; genus Cucumovirus) were the most frequent viruses among those surveyed, while tobamoviruses (genus Tobamovirus) were detected at low frequency. PVMV showed a high heterogeneity across AEZs, which may be related to climatic, ecological or agronomical conditions, whereas CMV was more homogeneously distributed. The molecular diversity of CMV and PVMV were analysed from partial genome sequences. Despite the low number of CMV isolates characterized, two molecular groups were revealed, one corresponding to subgroup IA and the other to reassortants between subgroups IA and IB. RNAs 1 and 3 of the reassortants clustered with the IB subgroup of CMV isolates, whereas their RNA 2 clustered with the IA subgroup. Importantly, RNA 1 of CMV isolates of the IB subgroup has been shown to be responsible for adaptation to pepper resistance. The diversity of PVMV in the VPg‐ and coat protein‐coding regions revealed multiple clades. The central part of the VPg showed a high level of amino acid diversity and evidence of positive selection, which may be a signature of adaptation to plant recessive resistance. As a consequence, for efficient deployment of resistant pepper cultivars, it would be desirable to examine the occurrence of virulent isolates in the CMV or PVMV populations in Côte d'Ivoire and to follow their evolution as the resistance becomes more widely deployed.     

Radiocarbon Content in Urban Atmospheric Aerosols

We attempted to elucidate seasonal variations in fossil-fuel-derived carbon (FC) and biomass-derived carbon (BC) in urban atmospheric aerosols. We undertook continuous measurements of the composition of fine particle (PM_2.1) in central Tokyo, including the ¹⁴C/¹²C ratio. The percent modern carbon (pMC) contained in all samples averaged 43, and the highest was 54 in late December and the lowest was 31 in early August. From the observed carbonaceous component concentrations and the pMC we could calculate the content ratio of FC and BC in PM_2.1 and investigate their seasonal variations. Although there was almost no seasonal variation in the ratio of FC, the ratio of BC was observed to rise in early winter. This indicates that FC is influenced by the emission sources without seasonal variations (such as automobiles driven in urban areas). Furthermore, there is significant correlation between BC and organic carbon (OC), and even for urban areas, it is considered that the contribution of biomass carbon to OC in PM_2.1 is high.     

Single oral β-cryptoxanthin administration increases its serum concentration and enhances peripheral blood neutrophil function in Holstein cattle

We investigated the effect of oral administration of β-cryptoxanthin (β-CRX) on its serum concentration and peripheral neutrophil functions by the chemiluminescence (CL) response in Holstein cattle. A single oral administration of β-CRX was performed for serum β-CRX concentration (0, 0.05, 0.1, or 0.2 mg/kg body weight [BW]) and for peak CL response of peripheral neutrophils (0.2 mg/kg BW). The serum β-CRX concentration was peaked on 2 days after, similar to peak CL response on 3 days after β-CRX administration. Therefore, a single oral administration of β-CRX (0.2 mg/kg BW) induces higher serum concentration and concurrently enhances bactericidal ability of peripheral neutrophils in Holstein cattle.     

Influence of overplanting paddy rice on irrigation water delivery performance: a case study in the Dakalt branch canal,Nile Delta of Egypt

In the North Nile Delta of Egypt, the impacts of overplanting paddy rice on water delivery performance have not been discussed quantitatively. Further, the amount of water that could have been saved if farmers would follow the planned area is unknown. In this study, water delivery performance was assessed by comparison of actual paddy rice planting and the government’s planned conditions. For both conditions, performance indicators relating to adequacy, equity, and dependability were analyzed across six locations in conjunction with the branch canal water level in 2013 and 2014. Based on the difference between the actual water supply and planned water demand, the amount of water that could have been saved for downstream uses was calculated. The average adequacy for the investigation period was good at one location, fair at 2 locations, and poor at 3 locations in both years. Further, adequacy under both actual and planned conditions was poor in late July at all locations. The planned adequacy and dependability downstream and equity among locations improved compared to the actual condition in both years. Under the condition that paddy rice area is the upper limit planned by the government, about 12.3% and 9.6% of water could be potentially saved in each year. The difference between actual and planned water delivery performance is caused by the branch canal’s low water level. Control of overplanting paddy rice and coordination of water distribution among water user associations would improve stable water level in the canal and, eventually, water delivery performance.