Impacts of Bolbophorus damnificus (Digenea: Bolbophoridae) on Production Characteristics of Channel Catfish,Ictalurus punctatus,Raised in Experimental Ponds

Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (≥34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) was unknown. Laboratory and field studies were conducted to evaluate sublethal acute (early stage) and chronic (late stage) trematode infection impacts on catfish production. Fish raised in ponds seeded with ram's horn snails from ponds harboring active B. damnificus outbreaks resulted in infection prevalence ranging from 1.6 to 20.4%. Compared to fish raised in ponds not seeded with infected snails (0% prevalence), fish biomass, number harvested, and total feed fed were significantly lower. These data agree with previous studies where mild infections reduced feed consumption, fish production, and economic returns. Infected fish were collected from ponds and used in a laboratory growth study. Once removed from the infection source, weight gain, growth rate, feed consumption, and feed efficiency were equal to or greater than trematode‐free fish. This suggests that although early B. damnificus infection (premetacercarial development) can severely impact production, infection has little impact on performance once metacercarial cysts are fully developed, and the infection source is removed.     

An investigation of the disease status of village poultry in Mauritania

Three contagious poultry diseases in Mauritania were studied. Serum samples and tracheal swabs were taken from 80 chickens in village poultry flocks in each of three different regions. Antibodies against Newcastle disease virus (NDV) were detected in 4.8% of chickens, antibodies against Gumboro disease virus in 15.8% of chickens and antibodies against Salmonella pullorum in 6.2% of chickens. Six isolates of NDV were made, of which four formed plaques on chicken embryo fibroblast monolayers. Seropositivity was highest in the Trarza region, bordering the River Senegal, and four out of six of the NDV isolates were made from chickens in this region.     

Serodiagnosis of Lyme disease in UK dogs

Lyme disease is a chronic, multisystemic, inflammatory disorder of man and animals associated with infection by the tick-borne spirochaete, Borrelia burgdorferi. Lyme disease was recently reported for the first time in a dog in the UK (May and others 1990). Using an enzyme-linked immunosorbent assay (ELISA), we have performed a serological survey to investigate the prevalence of antibodies to B burgdorferi in UK dogs. The survey has shown that dogs from many areas in the UK have serum antibodies to B burgdorferi, that the presence of serum antibodies is associated with known exposure to ticks and that some dogs seropositive for B burgdorferi have clinical signs consistent with Lyme disease. High levels of serum anti-Borrelia antibodies are not diagnostic for canine Lyme disease, but, in association with appropriate clinical signs, they help to confirm the diagnosis in suspected cases.     

The role of p38 mitogen-activated kinase (MAPK) in the mechanism regulating cyclooxygenase gene expression in equine leukocytes

The goal of this study was to define the role for p38 mitogen-activated kinase (MAPK) in the signaling mechanism regulating pro-inflammatory cyclooxygenase (COX) gene expression in lipopolysaccharide (LPS)-activated equine leukocytes for the purposes of identifying novel targets for anti-inflammatory therapy in endotoxemic horses. The p38 MAPK has been shown to positively regulate inflammatory gene expression in human leukocytes and can be activated by a variety of stimuli including LPS, TNF-alpha, and IL-1. Activation-associated phosphorylated p38 MAPK has been implicated in the up-regulation of several inflammatory genes, including COX-2 which ultimately results in the production of prostanoids that are responsible for the pathophysiology associated with endotoxemia. Our hypothesis is that activation of p38 MAPK is essential for LPS-induced COX-2 expression in equine peripheral blood leukocytes. We tested our hypothesis by investigating the effects of the specific p38 MAPK inhibitors SB203580 and SB202190 on LPS-induced COX-2 protein expression and PGE(2) production in equine leukocytes. LPS stimulation activated p38 MAPK and increased COX-2 expression in a dose-dependent manner with maximal activation observed after 30min and 4h, respectively, at a concentration of 10 ng/ml LPS. In contrast, LPS stimulation did not affect COX-1 protein expression. Pretreatment with SB203580 or SB202190 significantly inhibited LPS-induced activation-associated p38 MAPK phosphorylation, COX-2 mRNA and protein levels, and PGE(2) production in equine leukocytes. Maximal inhibition of LPS-induced COX-2 protein expression was achieved at a concentration of 10 microM SB203580. We concluded that p38 MAPK is essential for LPS-induced COX-2 expression suggesting that p38 MAPK is a potential target for anti-inflammatory therapy during equine endotoxemia.     

Waste water renovation through soil percolation

A laboratory experiment simulating high-rate effluent renovation by soil percolation involved leaching secondary sewage effluent through columns of three differing soils. Analyses of P in 22 leachate collections and distribution of both organic and inorganic P in column sections revealed the mechanisms of P removal, the influence of differing soil properties, and the effect of continuous utilization. Renovation of effluent P was greatest with percolation through columns of acid Milner soil which contains abundant Al and Fe, and, although Squilax soil removed more P from initial leachings due to its higher exchangeable Ca content, Glenmore soil was the more suitable of these two alkaline soils over the long term. The leachate N0₀3-N levels were lower than the original N0₃-N content of effluent for the first ten leachings but N0₃-N enrichment occurred for the last effluent percolations through all three soils. Analyses of Ca, Mg, K, and Na in leachates and soil columns indicated losses of exchangeable cations from the calcareous Squilax and Glenmore soils enriched effluent content and the accumulation of the cations in the acid soil reduced concentrations in effluent that passed through Milner soil.     

水分状况及硼素营养对油菜苗期根系生长及硼营养效率的影响

采用温室盆栽试验 ,研究了不同土壤水分条件下施硼对油菜苗期根系生长、硼吸收、利用及其移动性的影响。结果表明 ,随土壤含水量、施硼量的下降 ,油菜根长、根体积、根系生长速率、根 /冠比减小 ,根系及地上部干物质积累降低 ,植株地上部硼浓度及含硼量下降。而硼利用效率、硼运移指数则随土壤含水量、施硼量的下降而升高。不同油菜品种的根系形态参数 (包括根长、根体积、根干重、根冠比及根系生长速率 )、硼利用效率及运移指数存在明显差异 ,即在相同条件下 ,V1根系较发达 ,硼利用效率、运移指数均高于V4 。研究认为 ,根系发达程度、硼利用效率及硼移动性大小是不同基因型油菜耐缺硼差异的重要因素。     

Local population structure of a naturally occurring metapopulation of the quokka (Setonix brachyurus Macropodidae: Marsupialia)

We investigated the population structure of the quokka (Setonix brachyurus) on the mainland of Western Australia using mark–recapture techniques. Seven previously known local populations and one unconfirmed site supporting the preferred, patchy and discrete, swampy habitat of the quokka were trapped. The quokka is now considered as locally extinct at three sites. The five remaining sites had extremely low numbers, ranging from 1 to 36 individuals. Population density at these sites ranged from 0.07 to 4.3 individuals per hectare. There has been no response to the on-going, 6 year fox control programme occurring in the region despite the quokkas’ high fecundity and this is due to low recruitment levels. The remaining quokka populations in the northern jarrah forest appear to be the terminal remnants of a collapsing metapopulation.