ABSTRACT
Age-0+ year juvenile Argentine hake Merluccius hubbsi (60-150 mm total length, L(T)) from San Jorge Gulf, north Patagonian shelf region of the Argentine Sea, had an almost exclusively pelagic diet dominated by the hyperiid amphipod Themisto gaudichaudii and the euphausiid Euphausia lucens. This suggested that final settlement and permanent demersal habitat utilization might not, as previously reported, occur at earlier sizes (c. 20 mm L(T)). Their feeding strategy involves specialization at a population level towards both the main pelagic prey, indicating a narrow trophic niche. Novel data are provided which contribute to the growing body of information in relation to the age-0+ year transitional stage in demersal fishes and particularly to M. hubbsi recruitment in the Argentine Sea.
Subject(s)
Behavior, Animal , Feeding Behavior , Gadiformes/physiology , Animals , Atlantic Ocean , Food Chain , Gastrointestinal Contents , Models, BiologicalABSTRACT
The biodegradation of oil products in the environment is often limited by their low water solubility and dissolution rate. Rhamnolipids produced by Pseudomonas aeruginosa AT10 were investigated for their potential to enhance bioavailability and hence the biodegradation of crude oil by a microbial consortium in liquid medium. The characterization of the rhamnolipids produced by strain AT10 showed the effectiveness of emulsification of complex mixtures. The addition of rhamnolipids accelerates the biodegradation of total petroleum hydrocarbons from 32% to 61% at 10 days of incubation. Nevertheless, the enhancement of biosurfactant addition was more noticeable in the case of the group of isoprenoids from the aliphatic fraction and the alkylated polycyclic aromatic hydrocarbons (PHAS) from the aromatic fraction. The biodegradation of some targeted isoprenoids increased from 16% to 70% and for some alkylated PAHs from 9% to 44%.
Subject(s)
Glycolipids/biosynthesis , Petroleum/metabolism , Pseudomonas aeruginosa/metabolism , Biodegradation, Environmental , Culture Media , Emulsions/metabolism , Glycolipids/chemistry , Glycolipids/metabolism , Petroleum/analysis , Polycyclic Aromatic Hydrocarbons/metabolism , Soil Microbiology , Soil Pollutants/metabolism , Terpenes/metabolism , Time FactorsABSTRACT
The most important components of wool scouring effluent grease are esters of sterols. Cholesteryl palmitate (CP) is the main ester in this grease. In this paper, the influence of the ester concentration in the anaerobic digestion and the relative rate of the different degradation steps, are studied. The experiment was carried out to measure methane production in the anaerobic degradation of acetate, palmitic acid (PA) and CP. A first-order kinetic model was assumed for hydrolysis and Monod models were assumed for both the methanogenic and acetogenic steps. Maximum hydrolysis rate was found to be around 20 times faster than the maximum methanogenic reaction rate during the experience. The lanolin emulsion drop size effect was also evaluated employing fine and coarse stock lanolin emulsions and no adapted sludge. Concentrations of 13.7 to 4.6 gCOD x l(-1) were employed. In a previous study, the effect of palmitic acid emulsion size was found important when similar sludge was tested. When esters are degraded, a significant effect of drop size on the degradation rate was not found. The difference between CP and PA emulsions behavior could be due to the fact that cholesterol produced during the ester degradation has a protective effect on the sludge.
Subject(s)
Bacteria, Anaerobic/physiology , Cholesterol Esters/metabolism , Biodegradation, Environmental , Bioreactors , Hydrolysis , Industrial Waste , Kinetics , Textile Industry , Waste Disposal, Fluid , WoodABSTRACT
The strong flow wastewater from a wool scouring industry is treated by a combination of anaerobic digestion and physico-chemical postreatment. Based on previous laboratory results (Gutiérrez et al., 1999), three anaerobic baffled reactors (ABR) of 300 m3 each were built, processing 60% of the strong flow of a wool scouring mill for about two years. COD and grease removal in the anaerobic reactors were 47-50% and 50-55% respectively, with an organic load between 8.9 and 6.7 kg COD/m3 d. The effluent of the anaerobic reactors was assayed with additives in an industrial decanter centrifuge. As results of these assays, all the effluent of the three reactors was sent to the decanter centrifuge after dosing additives. Overall COD and grease removal of the integrated system were 87% and 93% respectively. Dosage of coagulation-flocculation additives was optimized in a continuous flocculation device. The proposed treatment is cheaper and easier to control than others alternatives with COD removal higher than 93%.
Subject(s)
Waste Disposal, Fluid/methods , Water Purification/methods , Wool , Animals , Bacteria, Anaerobic/physiology , Bioreactors , Equipment Design , Flocculation , Oxygen/metabolism , Sheep , Water MovementsABSTRACT
BACKGROUND: In recent years, the clinical profile of primary hyperparathyroidism (PH) is predominantly characterized by mild or asymptomatic forms. In this context, the effects of the PH on bone metabolism reach a growing importance in the adoption of therapeutic decisions. PATIENTS AND METHODS: 116 patients with PH were studied, 95 women (25 premenopausal, 70 postmenopausal) and 21 males. In all cases parathyroidectomy criteria were evaluated. Bone mineral density (BMD) was determined in 71 patients in lumbar spine (LS) and femoral neck by dual-X-Ray absorptiometry (DXA) and the influence of this measurement in the decision of surgical treatment was analyzed. RESULTS: The patients with PH showed a significant reduction of BMD at all sites (p < 0.001) and 71.8% met osteoporosis densitometric criteria. The most frequent parathyroidectomy criteria was the presence of specific clinical manifestations (51.7%) followed by decrease of the BMD in LS (49.3%). The probability of meeting criteria for surgical treatment was significantly higher in patients in which BMD was measured (odds ratio: 3.09 [1.03-9.22]; p = 0.036). CONCLUSIONS: In its current presentation, PH presents a significant decrease of bone mass. The systematic performance of bone densitometry has a decisive influence in its appropriate management.
Subject(s)
Absorptiometry, Photon , Bone Density , Hyperparathyroidism/diagnosis , Adult , Age Factors , Bone Diseases, Metabolic/diagnosis , Female , Femur Neck , Humans , Hyperparathyroidism/surgery , Lumbar Vertebrae , Male , Middle Aged , Odds Ratio , Osteoporosis/diagnosis , Parathyroidectomy , Postmenopause , Sex FactorsABSTRACT
The presence of porcine toxigenic E. coli (ETEC, VTEC) in 28 piggeries (5% of total) of the central and northeast region of Argentina was studied for a better understanding of the epidemiology of porcine strains. Samples were taken by rectal swabs from healthy piglets and from those with diarrhoea, in addition to their dams. Between 5-10 colonies were isolated from each one of 223 animals sampled from 1992 to 1997. By using specific primers each strain was screened by PCR for VT1, VT2all, VT2e, STIa, and LTI toxin genes. Only strains positive for any of the toxins mentioned above were screened for STb. Their O serogroups were determined by agglutination. All of the above enterotoxins and verocytotoxins were found in E. coli isolated from the animals. The STIa gene was detected in E. coli isolated from 27/127 piglets with diarrhoea, in comparison with LTI (4/127 pigs). No toxin gene was amplified from E. coli isolated from either healthy piglets or their dams. When strains isolated from 48 piglets without diarrhoea but showing delayed growth were analysed by PCR, their toxin profile was determined to be VT1 (1/48 piglets), VT2all (5/48), STIa (1/48), LTI (3/48) and VT2e (3/48). Serogroup O64 prevailed among ETEC; O138 prevailed for ETEC/VTEC strains. This is the first extensive study regarding porcine toxigenic E. coli in Argentina and constitutes an important database for the implementation of prevention measures.
Subject(s)
Enterotoxins/isolation & purification , Escherichia coli Infections/veterinary , Escherichia coli/pathogenicity , Swine Diseases/microbiology , Agglutination Tests/veterinary , Animals , Argentina/epidemiology , Bacterial Toxins/isolation & purification , DNA Primers/chemistry , DNA, Bacterial/chemistry , Electrophoresis, Agar Gel/veterinary , Escherichia coli/genetics , Escherichia coli Infections/epidemiology , Escherichia coli Infections/microbiology , Female , O Antigens/analysis , Polymerase Chain Reaction/veterinary , Prevalence , Rectum/microbiology , Shiga Toxin 1 , Shiga Toxins , Swine , Swine Diseases/epidemiologyABSTRACT
Virulence factors of Verotoxin-producing Escherichia coli (VTEC) strains isolated from hamburgers and ground beef were studied in Argentina by PCR. Their virulence profiles were correlated with those corresponding to strains isolated from calves and adult cattle. Most virulent profiles (VTs+ eae+ Mp+) were present in E. coli from healthy and diarrheic calves corresponding to O5:H-, O5:H27, O20:H?, O26:H11, O38:H?, O103:H-, O103:H2, O111:H-, O118:H16, O165:H-serotypes. The presence of the eae gene was significantly more frequent among VTEC strains isolated from calves (20/26; 76%) than from adult cattle (1/39; 2.5%) (p < 0.005). VT2+ eae- E. coli was prevalent in foods and adult cattle at slaughterhouse. The prevalence of the eae gene was similar between VTEC strains isolated from meat (0/21) and adult cattle (1/39; 2.5%) which constitutes the main population processed at slaughterhouses in Argentina. Serotyping showed that VTEC strains were distributed among 31 serotypes, some of which (O20:H19, O91:H21, O113:H21, O116:H21, O117:H7, O171:H2, OX3:H21) were shared between bovine and food strains. These O serogroups have been isolated from cases of haemorrhagic colitis (HC) and haemolyticuraemic syndrome (HUS) in humans in several continental European countries. This study confirms the role of cattle as a reservoir of many VTEC serotypes other than O157:H7 and represents a base for future diagnostic, prevention and control strategies of EHEC in this country. In addition, this study affirms the advantages of PCR-based screening of E. coli isolates given the finding of so many verotoxin-producing strains.
Subject(s)
Adhesins, Bacterial , Carrier Proteins , Escherichia coli Proteins , Escherichia coli , Meat/microbiology , Shiga Toxins , Animals , Argentina , Bacterial Outer Membrane Proteins , Cattle/microbiology , Escherichia coli/genetics , Escherichia coli/isolation & purification , Escherichia coli/pathogenicity , Food Microbiology , Genotype , Hemolytic-Uremic Syndrome/epidemiology , Humans , Polymerase Chain Reaction , Serotyping , Shiga Toxin 1 , Shiga Toxin 2 , Shiga Toxins/isolation & purification , VirulenceABSTRACT
Faecal swabs obtained from 126 calves and 118 cows in Argentina were investigated for the presence of verotoxin-producing Escherichia coli (VTEC). VTEC strains were recovered from 10 (23%) of 43 calves with diarrhoea, from 24 (29%) of 83 healthy calves, from 40 (44%) of 91 healthy cows waiting at the slaughterhouse, and from 6 (22%) of 27 healthy grazing cattle. PCR showed that 21 (9%) of animals carried VT1+ strains, 49 (20%) VT2+ strains and 10 (4%) VT1+ VT2+ strains. VT1+ strains predominated among calves (16% versus 0.8%; p < 0.001). The presence of eae gene was significantly more frequent among VTEC strains isolated from calves (78%; 46/59) than from cows (2%; 1/65) (p < 0.001). Furthermore, eae gene was more prevalent in VT1+ strains (97%; 32/33) than in VT2+ strains (14%; 10/70) (p < 0.001) and in VT1+ VT2+ strains (24%; 5/21) (p < 0.001). Sorbitol negative high virulent strains serogroups O157 were not detected. This study indicates that cattle are a reservoir of VTEC strains, and that eae gene is associated with VT1+ strains that are predominating among young animals. Fortunately, only adult animals are taken to the slaughterhouse, among which VTEC strains negative for eae gene are predominating.
Subject(s)
Bacterial Toxins/metabolism , Cattle Diseases/epidemiology , Cattle/microbiology , DNA, Bacterial/analysis , Diarrhea/veterinary , Escherichia coli Infections/veterinary , Escherichia coli/isolation & purification , Animals , Argentina/epidemiology , Bacterial Toxins/genetics , Base Sequence , Cattle Diseases/diagnosis , Cattle Diseases/microbiology , Diarrhea/microbiology , Escherichia coli/classification , Escherichia coli/genetics , Escherichia coli Infections/diagnosis , Escherichia coli Infections/microbiology , Molecular Sequence Data , Polymerase Chain Reaction , Prevalence , Reference Values , Serotyping , Shiga Toxin 1 , Species SpecificityABSTRACT
En este trabajo se presentan los resultados obtenidos en los ensayos, que tienen como antecedentes estudios previos a escala de laboratorio, los que permitieron realizar el diseño del reactor industrial de 300 m3, en actual construcción
Subject(s)
Sanitary Engineering , Wastewater , Water Purification , Upflow Anaerobic Reactors , CongressABSTRACT
En este trabajo se realizaron experiencias en un reactor a escala piloto, utilizando litio como trazador, para determinar el modelo de flujo de un reactor anaerobio del tipo manto de lodos (UASB). Se comparan los resultados de esta experiencia con otra realizada a escala de laboratorio y se discuten las diferencias de comportamiento a ambas escalas
Subject(s)
Sanitary Engineering , Upflow Anaerobic Reactors , Lithium , CongressABSTRACT
El presente trabajo consiste en el estudio de una planta de tratamiento de aguas residuales de frigorífico donde se procesan 650 bovinos por día. Se evaluó un sistema de tratamiento realizado en base a instalaciones existentes, sin introducir modificaciones significativas. Las instalaciones existentes permiten realizar tratamientos primarios (zarandas y flotación) y secundarios (reactor anaerobio y lagunas). En base a la evaluación primaria se concluyó que la presencia de sólidos suspendidos y grasas ocasiona problemas en los tratamientos biológicos. Para mejorar la eficiencia de los tratamientos primarios se realizaron ensayos de flotación con aire a presión obteniendo importantes mejoras(AU)
Subject(s)
Wastewater , Wastewater Treatment Plants/methods , UruguaySubject(s)
Industrial Waste , Stabilization Ponds , Wastewater , Wastewater Treatment Plants , UruguaySubject(s)
Industrial Waste , Stabilization Ponds , Wastewater , Wastewater Treatment Plants , UruguayABSTRACT
El presente trabajo consiste en el estudio de una planta de tratamiento de aguas residuales de frigorífico donde se procesan 650 bovinos por día. Se evaluó un sistema de tratamiento realizado en base a instalaciones existentes, sin introducir modificaciones significativas. Las instalaciones existentes permiten realizar tratamientos primarios (zarandas y flotación) y secundarios (reactor anaerobio y lagunas). En base a la evaluación primaria se concluyó que la presencia de sólidos suspendidos y grasas ocasiona problemas en los tratamientos biológicos. Para mejorar la eficiencia de los tratamientos primarios se realizaron ensayos de flotación con aire a presión obteniendo importantes mejoras
Subject(s)
Wastewater , Wastewater Treatment Plants , UruguayABSTRACT
1. Toads dehydrated to 80% of their standard weight (% SW) were rehydrated during 3 hr in distilled water. 2. Water permeability of the skin was positively correlated with the degree of dehydration in the range 80-100% SW. 3. Systemic administration of the beta-adrenergic agonist isoproterenol (5 mg/kg) 90 min after rehydration started (animals fully hydrated) increased skin permeability to the values observed in 80% SW dehydrated animals. 4. The administration of the beta-adrenergic blocker propranolol (5 mg/kg) 15 min before rehydration started produced a long-lasting decrease in water permeability during the 3 hr of rehydration. 5. The results are consistent with the hypothesis of a beta-adrenergic control of the water permeability of the skin during rehydration.