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Bacteriophage control of foodborne bacteriat.

Bacteriophages are measurable components of the natural microflora in the food production continuum from the farm to the retail outlet. Phages are remarkably stable in these environments and are readily recovered from soil, sewage, water, farm and processing plant effluents, feces, and retail foods. Purified high-titer phage lysates have been used for the species-specific control of bacteria during the pre- and postharvest phases of food production and storage. For example, the inhibition of the phytopathogens Erwinia amylovara and Xanthomonas campestris has reduced the incidence of diseases such as fire blight in apples and bacterial spot of tomato and peaches. Research on preslaughter treatment of food animals has demonstrated phage control of salmonellosis in chickens, enteropathogenic Escherichia coli infections in calves, piglets, and lambs, and E. coli O157:H7 shedding by beef cattle. Phages have also been applied to control the growth of pathogens such as Listeria monocytogenes, Salmonella, and Campylobacter jejuni in a variety of refrigerated foods such as fruit, dairy products, poultry, and red meats. Phage control of spoilage bacteria (e.g., Pseudomonas spp. and Brochothrix thermosphacta) in raw chilled meats can result in a significant extension of storage life. Phage biocontrol strategies for food preservation have the advantages of being self-perpetuating, highly discriminatory, natural, and cost-effective. Some of the drawbacks of biopreservation with phages are a limited host range, the requirement for threshold numbers of the bacterial targets, phage-resistant mutants, and the potential for the transduction of undesirable characteristics from one bacterial strain to another. Most research to date has involved experimentally infected plants and animals or artificially inoculated foods. This technology must be transferred to the field and to commercial environments to assess the possibility of controlling natural contaminants under more realistic production and processing conditions.

Animals↗

Yersinia enterocolitica infection in breeding colonies of ruffed lemurs.

Two outbreaks of yersiniosis caused by Yersinia enterocolitica occurred in breeding colonies of red ruffed lemurs (Varecia variegata rubra) and black and white ruffed lemurs (Varecia variegata variegata) housed in outdoor enclosures during the winter breeding season and spring birth season, respectively. Seven of 11 animals at risk in the combined outbreaks became ill, and 3 died of acute to chronic infection. Clinical signs included anorexia, lethargy, diarrhea, abdominal pain, and hyperpyrexia. Necropsy findings included ulcerative enterocolitis and multifocal necrosis and abscess formation in mesenteric lymph nodes, liver, spleen, kidneys, and lungs. Histologically, lesions were characterized by necrotizing inflammation containing masses of basophilic bacteria. Yersinia enterocolitica serotype 0:2 was isolated from lesions. Neomycin sulfate given orally and chloramphenicol given intramuscularly were effective in treatment early in the course of the disease or in mild cases. In severe cases, lemurs did not respond to antibiotic and fluid therapy. Exposure to soil contaminated with infected rodent feces, stress, and behavioral factors in the ruffed lemur species are believed to have precipitated the infection.

Animals↗

Production of clover broomrape seed germination stimulants by red clover root requires nitrate but is inhibited by phosphate and ammonium.

The effect of nutrients (nitrate, ammonium, urea, phosphate and potassium) on the production and/or exudation of germination stimulants for clover broomrape (Orobanche minor Sm.), a root holoparasite, by its host red clover (Trifolium pratense L.) was examined using hydroponically grown material. Potassium (K2SO4) concentrations up to 100 mg l-1 (based on K) did not affect the production of germination stimulants by red clover while, in contrast, phosphate (NaH2PO4) was highly inhibitory even at concentrations as low as 1 mg l-1 (based on P). Nitrate (NaNO3) markedly promoted stimulant production in a dose-dependent manner from 2 to 50 mg l-1 (based on N). Ammonium [(NH4)2SO4] had no effect at 2 mg l-1 (based on N) but was inhibitory at higher concentrations. Ammonium is known to be a seed germination inhibitor of root parasites, indicating that ammonium has a dual inhibitory action. Urea had no effect at 2 mg l-1 (based on N) but was promotive at higher concentrations. These results provide a basis for the inhibitory effects of nitrogen fertilizer on infection by root parasitic weeds, broomrapes and witchweeds, and explain why these parasites prevail in areas where there is lower phosphorus availability in soils.

Journal Article↗

Water relations of several hardwood species in response to throughfall manipulation in an upland oak forest during a wet year.

We investigated the effects of altered precipitation on leaf osmotic potential at full turgor (Psi(pio)) of several species in an upland oak forest during the 1994 growing season as part of a Throughfall Displacement Experiment at the Walker Branch Watershed near Oak Ridge, Tennessee. The main species sampled included overstory chestnut oak (Quercus prinus L.), white oak (Q. alba L.), red maple (Acer rubrum L.); intermediates sugar maple (A. saccharum L.) and blackgum (Nyssa sylvatica Marsh.); and understory dogwood (Cornus florida L.) and red maple. The precipitation treatments were: ambient precipitation; ambient minus 33% of throughfall (dry); and ambient plus 33% of throughfall (wet). Except in late September, midday leaf water potentials (Psi(l)) were generally high in all species in all treatments, ranging from -0.31 to -1.34 MPa for C. florida, -0.58 to -1.51 MPa for A. rubrum, and -0.78 to -1.86 MPa for Q. prinus. Both treatment and species differences in Psi(pio) were evident, with oak species generally exhibiting lower Psi(pio) than A. saccharum, A. rubrum, C. florida, and N. sylvatica. The Psi(pio) of C. florida saplings declined in the dry treatment, and Q. prinus, Q. alba, and A. saccharum all exhibited a declining trend of Psi(pio) in the dry treatment, although Psi(pio) of Q. prinus leaves increased in late August, corresponding to a recovery in soil water potential. Cornus florida exhibited osmotic adjustment with the largest adjustment coinciding with the period of lowest soil water potential in June. The only other species to exhibit osmotic adjustment was Q. prinus, which also maintained a lower baseline Psi(pio) than the other species. We conclude that a 33% reduction of throughfall is sufficient both to alter the water relations of some species in the upland oak forest and to enable the identification of those species capable of osmotic adjustment to a short-term drought during a wet year.

Journal Article↗

Removal of boron from aqueous solution by using neutralized red mud.

The adsorptive removal of boron from aqueous solution by using the neutralized red mud was studied in batch equilibration technique. The effects of pH, adsorbent dosage, initial boron concentration and contact time on the adsorption were investigated. The experiments demonstrated that boron removal was of a little fluctuation in pH range of 2-7 and it takes 20 min to attain equilibrium. The adsorption data was analyzed using the Langmuir and the Freundlich isotherm models and it was found that the Freundlich isotherm model represented the measured sorption data well.

Adsorption↗

A study of iron mineral transformation to reduce red mud tailings.

This study examines the effects of iron mineral transformation in an aluminum extraction process on the settling behavior, and the physical and chemical properties of the resulting red mud slurry that must be disposed of. By producing a red mud with a higher solid content, the total volume of mud slurry will also be reduced for a given alumina production rate and more caustic soda will be recovered. The settling behavior and the mineralogical, physical, and physico-chemical properties of one bauxite and three red muds processed under varying conditions were analyzed based on examination of the iron mineral transformations. The properties of red muds derived from the same bauxite can differ markedly due to variations in operating conditions of the Bayer process, such as temperature and the addition of a reducing agent. The settling of red mud can be improved by converting goethite into hematite and/or magnetite to produce a mud of larger particle size, smaller specific surface area, and larger specific gravity, characteristics which reduce the total volume of mud slurry to be disposed of and which allow for less potential contamination from caustic soda. This study also found that the by-product--Bayer sodalite--has the high exchange capacity for Na+ that might contribute to the long-term environmental problems.

Aluminum Oxide↗

Evidence for an antemortem injury of a burned head dissected from a burned body.

A 41-year-old woman was killed following blows to the head with a bat. Her body was burned and her head was dissected with a saw and hidden in the soil. Although the body was discovered within a few days of her death, the putrescent head was not located until four months later. A fracture of the left temporal bone was found in the head, which was partially charred. The confession of the murder suspect was unreliable, and the police suggested that the cause of death may not have been a head injury but asphyxia, and that the bone fracture to the head may have been caused after its dissection. It was therefore necessary to determine when the fracture was formed. The fracture line continued to the base of the skull, indicating that it was not due to heat. Magnetic resonance computed tomography (MR-CT) indicated the existence of a blood clot in the left mastoid cells, across which the fracture line passed. Upon sectioning of the skull with a saw, a dark red clot was located in the left mastoid cells, indicating that bleeding had occurred before the body was set alight. It seemed most logical to assume that the bone fracture was formed when the victim was alive, or before her body was burned.

Adult↗

Trace elements in western Canadian hard red spring wheat (Triticum aestivum L.): levels and quality assurance.

A monitoring program was conducted for trace elements in Western Canadian Hard Red Spring wheat (Triticum aestivum L.). Samples were selected from harvest survey samples submitted by producers from crop districts in Manitoba, Saskatchewan, and Alberta for 1996, 1997, and 1998 crops. The analytical quality control measures used in these surveys are described along with the results for Cd, Cu, Fe, Mn, Se, and Zn. Accuracy and precision for the analyses fell within the acceptable control limits. Year-to-year variations in grain chemistry were small for Cd, Mn, Se, and Zn, but Cu and Fe contents showed 12 and 9% decreases, respectively, over the 3 years. The overall variability for the plant-essential trace elements-Cu, Fe, Mn, and Zn-was low compared with that for Cd and Se. The spatial variation in crop chemistry across the Canadian Prairie wheat-producing region was greater than the year-to-year variations. Soil properties were major factors in controlling Cd and Se levels in grain.

Alberta↗

Effects of molybdenum on the organism (a review).

Molybdenum belongs to a group of essential microelements and occurs in all components of the environment. Major Mo sources for man are foods, especially vegetable, to a lesser extent drinking water. Its metabolism is primarily influenced by interaction with other metals, specifically copper and iron. In the organism it is primarily accumulated in the liver, kidneys, skin and hard tissues. In the blood it binds specifically with alpha-2-macroglobulin, in the erythrocytic membrane with spectrin; it enhances the osmotic resistance of red blood cells. From the organism it is eliminated in the urine, bile and feces. The biochemical importance of molybdenum lies in that it catalyzes the oxidation of xanthine and purine bases and the reduction of nitrates and molecular nitrogen; it is also present in the prosthetic group of flavoprotein enzymes. As shown in both epidemiological and animal studies, molybdenum ions may prevent dental caries. Long-term overexposure to Mo may produce molybdenosis (teart) in cattle. Increased exposures of humans may be primarily encountered in the foundry industry, but the toxic manifestations are invariably nonspecific, similarly as in the case of other heavy metals. Molybdenum-exposed workers may also show elevated uric acid concentrations in their blood, simultaneously with clinical symptoms resembling gout (gout-like syndrome). A similar finding may also occur among individuals living in areas characterized by elevated molybdenum and decreased copper contents in soil. The maximum allowable concentration limits established for soluble and insoluble molybdenum compounds in the workplace air have been accepted in many countries, but their values vary in a wide range. No specific exposure test for molybdenum has been developed as yet.

Adult↗

Lysosomal membrane stability in laboratory- and field-exposed terrestrial isopods Porcellio scaber (Isopoda, Crustacea).

Two established methods for assessment of the cytotoxicity of contaminants, the lysosomal latency (LL) assay and the neutral red retention (NRR) assay, were successfully applied to in toto digestive gland tubes (hepatopancreas) of the terrestrial isopod Porcellio scaber (Isopoda, Crustacea). In vitro exposure of isolated gland tubes to copper was used as a positive control to determine the performance of the two methods. Lysosomal latency and the NRR assay were then used on in vivo (via food) laboratory-exposed animals and on field populations. Arbitrarily selected criteria for determination of the fitness of P. scaber were set on the basis of lysosomal membrane stability (LMS) as assessed with in toto digestive gland tubes. Decreased LMS was detected in animals from all polluted sites, but cytotoxicity data were not in agreement with concentrations of pollutants. Lysosomal membrane stability in the digestive gland tubes of animals from an environment in Idrija, Slovenia that was highly polluted with mercury (260 microg/g dry wt food and 1,600 microg/g dry wt soil) was less affected than LMS in laboratory animals fed with 5 and 50 microg Hg/g dry weight for 3 d. This probably indicates tolerance of P. scaber to mercury in the mercury-polluted environment and/or lower bioavailability of environmental mercury. In animals from the vicinity of a thermal power plant with environmental mercury concentrations three to four orders of magnitude lower than those in Idrija, LMS was severely affected. In general, the LL assay was more sensitive than the NRR assay. The LMS assay conducted on digestive gland tubes of terrestrial isopods is highly recommended for integrated biomarker studies.

Animals↗

Effects of Fe deficiency chlorosis on yield and fruit quality in peach (Prunus persica L. Batsch).

The effects of iron (Fe) deficiency on fruit yield and quality were measured in two peach cultivars, Carson (yellow-skin fruit) and Babygold (red-skin fruit). In both cultivars, Fe deficiency caused major decreases in fruit fresh weight per tree and number of fruits per tree. Fruits from Fe-deficient peach trees had a smaller size, resulting in a large decrease in the percentage of commercially acceptable fruits, whereas fruit firmness was unaffected. In cv. Babygold, Fe deficiency greatly decreased the red color of the fruit skin. Part of these results was likely associated with a delay in fruit ripening. When fruits with similar appearance were compared, taking into account fruit size, color, and firmness, Fe deficiency generally led to higher concentrations of organic anions (especially succinate and quinate), vitamin C, and phenolic compounds and to lower total sugar/total organic acid ratios. This could lead to decreased fruit eating quality and to a slight improvement in fruit nutritional value.

Agriculture↗

Comparison of ultrasonic cleaning schemes: a pilot study.

OBJECTIVE: Ultrasonic cleaning is an effective method for cleaning dental instruments prior to sterilisation. However, there are few studies that directly compare precleaning and ultrasonic cleaning solutions. This study evaluated the efficacy of different ultrasonic cleaning schemes. METHOD AND MATERIALS: Twenty representative dental instruments, five of which were soiled with a mixture of blood and hydroxyapatite, were used in a series of cleaning runs. Cleaning employed a presoaking agent, ultrasonic cleaning, or a combination of both. Two presoaking agents (Non-ionic Ultrasonic Cleaning Solution and ProEZ Foaming Enzymatic Spray) plus five ultrasonic cleaners (UltraDose, General Purpose Cleaner, Co-enzyme Concentrate, Enzol Enzymatic Detergent, and Non-ionic Ultrasonic Cleaning Solution) were compared, with tap water serving as a control. There were two cleaning times: seven and 15 minutes. After rinsing, the working ends of the instruments underwent scrubbing for 20 seconds using a dental polishing brush held in a haemostat. After scrubbing, the brush and instrument were placed in a tube containing sterile saline. Vortexing of the tube lasted 30 seconds. Testing for the post-cleaning presence of blood involved Hemastix dipsticks. These sticks measure minute amounts of blood in urine and can detect as few as 35 red blood cells per ml. Comparisons of colour change were made to a standard scale followed by assignment of numeric values. RESULTS: Tap water was the poorest cleaning solution, while UltraDose was the most effective. Blood removal improved when cleaning time was increased from seven to 15 minutes. The combined effect of a presoak immersion followed by ultrasonic cleaning was the most effective cleaning scheme overall. Cleaning by either ultrasound or presoaking only was less effective. Some instruments were more difficult to clean than others. CONCLUSION: Within the constraints of the small number of test runs performed, it was concluded that application of a presoak agent before ultrasonic cleaning produced the most effective instrument-cleaning regimen.

Blood↗

Effects of sewage sludge on pH and plant availability of metals in oxidising sulphide mine tailings.

A field study was conducted adjacent to the tailings deposit of the Aitik copper mine in the north of Sweden to investigate the effects of sewage sludge on pH and plant availability of Al, Mn, Cu, Zn, Ni, Pb, As, Cr and Cd in the oxidising sulphide tailings. One treatment was supplied with sewage sludge, while the control received NPK-fertiliser. The tailings samples were collected at the beginning and the end of the growing season and extracted by NH(4)NO(3), NH(4)Ac-EDTA and HNO(3). Plant tissue concentrations of the elements were determined in the above-ground parts of barley (Hordeum vulgare) and red fescue (Festuca rubra). The application of sewage sludge resulted in higher crop yields compared to the control, although the buffering capacity and the metal immobilising effect of the sludge were limited. The pH decreased from 6.6 to 4.3 in the control and from 6.4 to 4.8 in the sludge-treated tailings during the growing season, probably due to sulphide oxidation in the tailings. This resulted in increased levels of soluble elements in all treatments studied. Application of sewage sludge resulted in elevated levels of soluble Zn and lower values of soluble As and Cd in the unaltered tailings but increased levels of specifically adsorbed Cu, Ni and As in the oxidised tailings. This was partly reflected in the plants, as the application of sewage sludge resulted in 67 mg Zn kg(-1) in barley grains and 60 mg Zn kg(-1) in red fescue shoots, both values twice as high as the corresponding values in the control, but lower As contents in both straw (0.3 mg kg(-1)) and grain (0.06 mg kg(-1)) of barley compared to the control (0.6 and 0.2 mg kg(-1), respectively). In addition, red fescue grown in sludge-treated plots contained significantly higher levels of Al, Cu, Pb, As and Cr compared to the control. The levels of several metals in barley and red fescue grown in both treatments exceeded background values found in the literature. The Cu content in barley straw exceeded 100 mg kg(-1) in both treatments and might be toxic to grazing animals. Thus, this study suggests that adding sewage sludge to the mine tailings at Aitik would not counteract the effects of the sulphide oxidation in the tailings. Furthermore, using a sequential extraction technique proved preferable to using total metal analysis in order to predict plant uptake of the elements in the tailings.

Biological Availability↗

Circumnutation of rice coleoptiles: its occurrence, regulation by phytochrome, and relationship with gravitropism.

It has been found that coleoptiles of dark-grown rice (Oryza sativa L.) seedlings undergo regular circumnutation in circular orbits with periods of about 180 min. Both clockwise and counter-clockwise movements were observed, but individual coleoptiles continued to rotate only in one direction. Light-grown seedlings did not show circumnutation. In fact, dark-grown seedlings were found to cease circumnutating in response to a pulse of red light (R). This light-induced inhibition of circumnutation was demonstrated to involve both a FR-inducible very-low-fluence response, solely mediated by phytochrome A, and a FR-reversible low-fluence response, mediated by phytochrome B and/or C. The R-induced inhibition of circumnutation showed temporal agreement with the R-induced inhibition of coleoptile growth, suggesting that the former results from the latter. However, about 25% of growth activity remained after R treatment, indicating that circumnutation is more specifically regulated by phytochrome. The R-treated coleoptile showed gravitropism. Investigation of the growth differential for gravitropic curvature revealed that gravitropic responsiveness was rather enhanced by R. The results suggested that gravitropism is not a cause of circumnutation. It remained probable, however, that gravity perception is a part of the mechanism of circumnutation. It is speculated that the circumnutation investigated aids the seedling shoot in growing through the soil.

Cotyledon↗

Biochemical Characterization and Subcellular Localization of the Red Kidney Bean Purple Acid Phosphatase.

Phosphatases are known to play a crucial role in phosphate turnover in plants. However, the exact role of acid phosphatases in plants has been elusive because of insufficient knowledge of their in vivo substrate and subcellular localization. We investigated the biochemical properties of a purple acid phosphatase isolated from red kidney bean (Phaseolus vulgaris) (KBPAP) with respect to its substrate and inhibitor profiles. The kinetic parameters were estimated for five substrates. We used 31P nuclear magnetic resonance to investigate the in vivo substrate of KBPAP. Chemical and enzymological estimation of polyphosphates and ATP, respectively, indicated the absence of polyphosphates and the presence of ATP in trace amounts in the seed extracts. Immunolocalization using antibodies raised against KBPAP was unsuccessful because of the non-specificity of the antiserum toward glycoproteins. Using histoenzymological methods with ATP as a substrate, we could localize KBPAP exclusively in the cell walls of the peripheral two to three rows of cells in the cotyledons. KBPAP activity was not detected in the embryo. In vitro experiments indicated that pectin, a major component of the cell wall, significantly altered the kinetic properties of KBPAP. The substrate profile and localization suggest that KBPAP may have a role in mobilizing organic phosphates in the soil during germination.

Journal Article↗

Tolerance to mercury chloride in Scenedesmus strains.

Mercury chloride toxicity was investigated in two strains of Chlorella and in a strain of Scenedesmus isolated from polluted areas in Tuscany (Italy). No Hg resistance was found in the autotrophic microorganisms isolated, but Scenedesmus sp. strain AR-2489, isolated from the Arno river, was able to grow at concentrations of up to 5 micrograms ml-1 of Hg. This concentration was twice that which inhibited growth of the two Chlorella strains and Scenedesmus acutus 8M, the reference strain from a culture collection. Photosynthesizing cells of Scenedesmus sp. AR-2489 showed reduced Hg uptake, with the highest percentage of Hg removal from the medium. Loss of Hg was not due to Hg(0) volatilization, as shown by a comparison test with the broad-spectrum Hg-resistant Pseudomonas putida FB1. The metabolic differences between Scenedesmus sp. strain AR-2489 and Siacatus strain 8M were: (1) higher growth rate (doubling time of 6.0 h versus 10.6 h); (2) higher O2 production rate (maximum 2 mumol h-1 mg-1 dry weight); and (3) higher intracellular pH during growth. The latter was imaged with a green fluorescence molecular probe (BCEFC-AM) and observed by scanning confocal laser microscopy (SCLM). The distribution of red-autofluorescence chlorophyll-a showed that strain AR-2489 had a rougher and hence more extended specific chloroplast surface than strain 8M. Hg tolerance in strain AR-2489 was related to the rapid increase in dissolved O2 in the medium and in intracellular pH; this caused a loss of soluble mercury transformed to insoluble mercury hydroxide, which is thermodynamically more stable at alkaline pH in highly oxygenated systems.

Chlorella↗

Storage of foliar-absorbed nitrogen and remobilization for spring growth in young nectarine (Prunus persica var. nectarina) trees.

The effectiveness of spraying foliage with urea to provide nitrogen (N) to augment the seasonal internal cycling of N in young nectarine trees (Prunus persica (L.) Batsch var. nectarina (Ait. f. Maxim.), cv. Stark Red Gold) was studied. One-year-old trees were grown with contrasting N supplies during the summer and foliage was sprayed with a 2% urea solution labeled with (15)N just before leaf senescence started. After leaf abscission had finished, the trees were repotted in sand and given no further N. Remobilization of both labeled and unlabeled N for leaf growth the following spring was quantified. Leaves absorbed between 58 and 69% of the (15)N intercepted by the canopy irrespective of tree N status. During leaf senescence, the majority of (15)N was withdrawn from the leaves into the shoot and roots. Remobilization of (15)N the following spring was also unaffected by tree N status. About 38-46% of (15)N in the trees was recovered in the new growth. More unlabeled N (derived from root uptake) was remobilized for leaf growth in the spring than was withdrawn from leaves during canopy senescence the previous autumn. Therefore, soil-applied N augmented N storage pools directly, and contributed more to N remobilization the following spring than did foliar-absorbed (15)N.

Journal Article↗

Characterization of a bioflocculant produced by the marine myxobacterium Nannocystis sp. NU-2.

The marine myxobacterium strain NU-2, which can grow on high concentrations (up to 7%) of NaCl, was isolated from a salt soil sample collected from the coast of the Huanghai Sea, China. Morphological properties and 16S rDNA sequence analysis indicated that the isolate is a novel species related to the genus Nannocystis. Nannocystis sp. NU-2 produced a new kind of flocculating substance in a starch medium with a yield of 14.8 g l(-1). The NU-2 flocculant was composed of 40.3% proteins and 56.5% polysaccharides, of which glucose, mannose and glucuronic acid were the principal constituents in the relative proportions of 5:4:1. The flocculation activity of the NU-2 flocculant depends strongly on cations such as Fe(3+) and Al(3+). When a 30 mg l(-1) FeCl(3) solution is present in kaolin clay suspension, 30 mg l(-1)of the flocculant produced a high flocculating activity value of 90%, which remained unchanged over an extensive pH range (pH 2.0-13.0). The flocculant was tested for its ability to bleach dyeing liquors, and the bleaching activities were 98.2% for acid red in 100 mg l(-1)of the flocculant and 99.0% for direct emerald blue in 50 mg l(-1)of the flocculant under test conditions. Use of the flocculant to bleach basic pink and cation emerald blue liquors was not effective.

Bacterial Proteins↗