Generation of oxidants and their role in the metabolism of oxygen in the survivability of filarial parasite Setaria digitata in cattle:a possible intervention strategy

Background:The goal of the current study was to identify the potential therapeutic targets by analyzing the production of oxidants and their effects on the antioxidant system of Setaria digitata,a filarial worm that was collected from the peritoneal cavity of recently butchered calves.Methods:S.digitata was collected and the mitochondria-like particles(MLP),somatic isolates and the post-nuclear fraction were prepared for investigation.The radical intensity and the antioxidant enzyme activity in these fractions were evaluated.The effect of diethylcarbamazine(DEC),Q0,omeprazole,and L-methyl arginine on NOS production in the worm was also evaluated.Results:Experiments showed that coelomic fluid and whole worm showed significant levels of Nitric oxide compared to other fractions.The cytosol of the worm showed higher NOS activity than MLP.Superoxide dismutase and nitric oxide(NO)levels were found to be higher in MLP fraction of the worm.It was also found that DEC did not have any effect on the prevention of NO,while Q0,omeprazole,and L-methyl arginine treatment showed a decrease in NO production significantly.Conclusion:The results showed that by using the existing drugs we could reduce the propagation of S.digitata by inhibiting the production of NO.

Influences of diel and tidal cycles on fish assemblage in eelgrass(Zostera marina) bed of southern Korea during autumn

Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl.A total of 1 346 fishes belonging to 19 species were collected at spring tide,whereas 1 115 fishes belonging to 17 species were at neap tide.The common fish species were Nuchequula nuchalis,Acanthogobius flavimanus,Takifugu niphobles,Acentrogobius pflaumii,and Pholis nebulosa with the former three species dominating at spring tide,while the latter two species being abundant at neap tide.Diel variation in abundance was significant with higher abundance at night than day,but there were no significant differences between spring and neap tides,and between ebb and flood tides（three-way ANOVAs）.Diel variation in the abundance of fishes may be influenced by tidal range and cycle,and day-night differences of food availability and behaviors of fishes indirectly.Non-metric multidimensional scaling（n MDS） ordination and analysis of similarity（ANOSIM） results revealed significant differences in species compositions both between day and night,and between spring and neap tide.Eelgrass beds are highly productive marine ecosystem,and thus,our results will contribute to conservation of seagrass ecosystem in the study area.

Identifying the turbulent flow developing inside and around the bottom trawl by Electromagnetic Current Velocity Meter approach in the flume tank

The Knowledge of turbulent flow developing inside and around the bottom trawl net is of great importance not only for improving the hydrodynamic performance of the gear but also for the selectivity via the fish response,such as the herding response or escape behavior.The 3-D Electromagnetic Current Velocity Meter(ECVM)measurements were performed to investigate the effect of turbulent flow on the bottom trawl net performance and to analyze the turbulence intensity and velocity ratio inside and around different parts of the trawl net.Proper orthogonal decomposition(POD)method was applied in order to extract the phase averaged mean velocity field of turbulent flow from each available ECVM instantaneous velocity.The results demonstrated the existence of turbulence flow,consisting of turbulent boundary layer flow and the turbulence due to the trawl wake developing all inside and around the bottom trawl net.Increasing input streamwise velocity results in faster trawl movement and a significant turbulent flow.The maximum turbulence intensity inside and around trawl wing,square part,first belly,second belly,third belly,cod-end is 0.95%,1.34%,3.40%,4.10%,4.25%and 3.80%,respectively.It was found that the mean velocity field in a turbulent flow inside and around trawl net cod-end recovered on the average was~77.58%of the input streamwise velocity.It is~12.92%,~13.07%,~11.40%,~13.00%and~0.45%less than that inside and around trawl wing,square part,first belly,second belly,and third belly of the bottom trawl net,respectively.The turbulent flow behavior depends strongly on the structure oscillation,input streamwise velocity and,porosity of the net structure.It is necessary to take into account the velocity reduction inside and around a different part of the trawl net to improve the entire drag force determination,cod-end design,and further selectivity control of the fishing gear.