Filtration of Green Algae and Cyanobacteria by Freshwater Mussels in the Partitioned Aquaculture System

Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters.     

Effects of intravenous sodium bicarbonate and sodium acetate on equine acid-base status

Changes in blood gases, pH, and plasma electrolyte concentrations in response to intravenously infused sodium bicarbonate (NaHCO₃) and sodium acetate (NaCH₃CO₂) solutions (1.34 mEq/mL) in 5 light breed mares were investigated. Jugular venous blood samples were collected before and after completion of the infusions in 20-minute intervals for 200 minutes. Infusion of sodium bicarbonate and sodium acetate caused significant (P < .00l) increases in blood pH and bicarbonate ion concentration that persisted throughout the collection period. The elevation in blood pH and bicarbonate ion concentrations was greater (P < .01) for sodium bicarbonate than for sodium acetate immediately after the completion of the infusions but was not different (P > .05) thereafter. There were significant reductions (P < .01) in plasma-ionized calcium and potassium after infusion of both sodium bicarbonate and sodium acetate. This study found that significant metabolic alkalosis in horses and corresponding shifts in electrolyte concentrations can be induced by intravenous infusion of solutions of either sodium bicarbonate or sodium acetate, and they persist for at least 3 hours. These data show that the short-term elevation in pH and bicarbonate ion concentration is momentarily higher after infusion of sodium bicarbonate. This is likely due to the direct infusion of bicarbonate ions in the sodium bicarbonate treatment, such that further metabolism is not required to be effective. However, the longer-term alkalosis did not differ between isomolar solutions of sodium bicarbonate and sodium acetate.     

Modelling land cover transitions: A solution to the problem of spatial dependence in data

Raster-based spatial land cover transition models (LCTMs) are widely used in landscape ecology. However, many LCTMs do not account for spatial dependence of the input data, which may artificially fragment the output spatial configuration. We demonstrate the consequences of ignoring spatial dependence, thus assigning probabilities randomly in space, using a simple LCTM. We ran the model from four different initial conditions with distinct spatial configurations and results indicated that, after 20 simulation steps, all of them converged towards the spatial configuration of the random data set. From an ecological perspective this is a serious problem because ecological data often exhibit distinct spatial configuration related to ecological processes. As a solution, we propose an approach (region approach) that accounts for spatial dependence of LCTM input data. Underlying spatial dependence was used to apply spatial bias to probability assignment within the model. As a case study we applied a region approach to a Vegetation Transition Model (VTM); a semi-Markovian model that simulates forest succession. The VTM was applied to approximately 500,000 ha of boreal forest in Ontario, at 1 ha pixel resolution. When the stochastic transition algorithms were applied without accounting for spatial dependence, spatial configuration of the output data became progressively more fragmented. When the VTM was applied using the region approach to account for spatial dependence output fragmentation was reduced. Accounting for spatial dependence in transition models will create more reliable output for analyzing spatial patterns and relating those patterns to ecological processes.This revised version was published online in May 2005 with corrections to the Cover Date.     

Treatment of canine haemangiosarcoma with suberoylanilide hydroxamic acid, a histone deacetylase inhibitor

A case report is presented by describing the treatment of a 12‐year‐old dog – diagnosed with haemangiosarcoma (HSA) – with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor. The drug was administered orally, on a daily basis, approximately 2 weeks post‐splenectomy at a dose of 3 mg kg^?1. HSA is a lethal malignancy of the endothelium, which is usually disseminated by the time it is diagnosed. Median survival time, usually, is no longer than 80 days. Following treatment with SAHA, no sign of malignant growth could be discerned by means of diagnostic abdominal ultrasound, chest X‐ray or with the help of clinical symptoms, over a period of >1000 days. The precise mechanism by which HDAC inhibitors exert their anti‐cancer effects is uncertain, but evidence suggests that exposure to SAHA generates hyperacetylated chromosomal histones, which, in turn, facilitates the expression of tumour suppressor genes turned off by epigenetic mechanisms during neoplastic transformation of the endothelium.     

A perspective on the measurement of time in plant disease epidemiology

The growth and development of plant pathogens and their hosts generally respond strongly to the temperature of their environment. However, most studies of plant pathology record pathogen/host measurements against physical time (e.g. hours or days) rather than thermal time (e.g. degree-days or degree-hours). This confounds the comparison of epidemiological measurements across experiments and limits the value of the scientific literature.     

Association between quantitative bacterial culture of bronchoalveolar lavage fluid and antibiotic requirement in dogs with lower respiratory tract signs

BackgroundHistorically, positive bacterial cultures from the lower respiratory tract (LRT) have been considered clinically relevant when quantitative bacterial cultures of bronchoalveolar lavage fluid (BALF) were >1700 colony forming units (cfu)/mL. However, this threshold might not accurately predict a requirement for antibiotics.ObjectivesTo study whether quantitative BALF bacterial culture results were predictive of antibiotic requirement in dogs with LRT signs.AnimalsThirty‐three client‐owned dogs.MethodsCross‐sectional study. Dogs with positive quantitative bacterial culture of BALF were included. Dogs were divided into 2 groups, depending on whether they had a LRT infection requiring antibiotics (LRTI‐RA) or LRT disease not requiring antibiotics (LRTD‐NRA), based on thoracic imaging features, presence of intracellular bacteria on BALF cytology, and response to treatment. Predictive effect of cfu/mL and BALF total nucleated cell count (TNCC) on antibiotic requirement, adjusting for ongoing or prior antibiotic therapy and age, were studied using logistic regression.ResultsTwenty‐two and 11 dogs were included in the LRTI‐RA and LRTD‐NRA groups, respectively. The cfu/mL was not significantly predictive of antibiotic requirement, independent of ongoing or prior antibiotic treatment and age (LRTI‐RA: median, 10 000 cfu/mL; range, 10‐3 × 10⁸; LRTD‐NRA: median, 10  000 cfu/mL; range, 250‐1.3 × 10⁹; P = .27). The TNCC was not significantly predictive of antibiotic requirement when only dogs with bronchial disease were considered (LRTI‐RA: median, 470 cells/μL; range, 240‐2260; LRTD‐NRA: median, 455 cells/μL; range, 80‐4990; P = .57).Conclusion and Clinical ImportanceThe cfu/mL is an inappropriate measure for determining whether antibiotics are of benefit in dogs with LRT signs.     

氯——被误解的杀菌剂

氯的使用可有效减少家禽胴体和屠宰加工厂的细菌。但是,我们有必要对氯有一个更好的认识和管理。