A nitric oxide-inducible lactate dehydrogenase enables Staphylococcus aureus to resist innate immunity

Staphylococcus aureus is one of the most successful human pathogens, colonizing 2 billion individuals worldwide and causing invasive infections even in immunocompetent hosts. S. aureus can evade multiple components of host innate immunity, including the antimicrobial radical nitric oxide (NO.) produced by activated phagocytes. We show that S. aureus is capable of metabolically adapting to nitrosative stress by expressing an NO.-inducible L-lactate dehydrogenase (ldh1, SACOL0222) divergently transcribed from the NO.-detoxifying flavohemoglobin (hmp). L-Lactate production allows S. aureus to maintain redox homeostasis during nitrosative stress and is essential for virulence. NO.-inducible lactate dehydrogenase activity and NO. resistance distinguish S. aureus from the closely related commensal species S. epidermidis and S. saprophyticus.     

Heterotrophic Production of Omega-3 Long-Chain Polyunsaturated Fatty Acids by Trophically Converted Marine Diatom Phaeodactylum tricornutum

We have created via metabolic engineering a heterotrophic strain of Phaeodactylum tricornutum that accumulates enhanced levels of the high value omega-3 long chain polyunsaturated fatty acid (LC-PUFAs) docosahexaenoic acid (DHA). This was achieved by generation of transgenic strains in which the Δ5-elongase from Ostreococcus tauri was co-expressed with a glucose transporter from the moss Physcomitrella patens. This double transformant has the capacity to grow in the dark in liquid medium supplemented with glucose and accumulate substantial levels of omega-3 LC-PUFAs. The effects of glucose concentrations on growth and LC-PUFA production of wild type and transformed strains cultivated in the light and dark were studied. The highest omega-3 LC-PUFAs accumulation was observed in cultures grown under mixotrophic conditions in the presence of 1% glucose (up to 32.2% of total fatty acids, TFA). Both DHA and EPA are detected at high levels in the neutral lipids of transgenic cells grown under phototrophic conditions, averaging 36.5% and 23.6% of TFA, respectively. This study demonstrates the potential for P. tricornutum to be developed as a viable commercial strain for both EPA and DHA production under mixo- and heterotrophic conditions.     

Relationship of clonal mean to the uniformity and stability of tuber specific gravity in potatoes

Regression analysis of plot mean and plot standard deviation for specific gravity of tubers from 190 unreplicated 12-hill breeding plots, was used to study the relationship of mean and within-plot uniformity. Using two data sets from the Western Regional Potato Variety Trial, regression analysis of clone mean for specific gravity within a location on overall location mean was used to study the relationship of mean and inter-location stability. A highly significant (p>0.01) but very weak (r²=0.04) positive coefficient of determination existed between plot means and plot standard deviations. No relationship was found for mean specific gravity of clones and their stability across different environments. The results suggest that selection of high specific gravity combined with uniformity and/or stability is a feasible goal for breeding programs.     

Incorporation and stabilization of omega-3 fatty acids in surimi made from cod, Gadus morhua

Surimi containing omega-3 fatty acids from algal oil was prepared by the addition of oil-in-water emulsions or bulk oil. Emulsion and bulk oil were added separately to surimi to provide approximately 500 mg of omega-3 fatty acids per serving of surimi (85 g). Addition of the emulsion had no effect on surimi gel strength, whereas bulk oil decreased gel strength an average of 31%. All surimi treatments containing algal oil increased in Hunter b values due to the presence of carotenoids in the oil. Among cryoprotectants, sodium tripolyphosphate was the major surimi additive responsible for retarding the formation of lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Lipid hydroperoxide and TBARS formation was lower in surimi containing bulk oil compared to surimi with emulsified oil. Both EDTA and lipid soluble antioxidants were able to decrease lipid oxidation in surimi fortified with omega-3 fatty acids. This suggests that surimi containing nutritionally beneficial omega-3 fatty acids could be developed with good oxidative stability and gel strength.     

Phytochemical composition and pigment stability of Açai (Euterpe oleracea Mart.)

Anthocyanin and polyphenolic compounds present in a?ai (Euterpe oleracea Mart.) were determined and their respective contribution to the overall antioxidant capacity established. Color stability of a?ai anthocyanins against hydrogen peroxide (0 and 30 mmol/L) over a range of temperatures (10-30 degrees C) was also determined and compared to common anthocyanin sources. Additionally, stability in a model beverage system was evaluated in the presence of ascorbic acid and naturally occurring polyphenolic cofactors. Cyanidin 3-glucoside (1040 mg/L) was the predominant anthocyanin in a?ai and correlated to antioxidant content, while 16 other polyphenolics were detected from 4 to 212 mg/L. Red grape anthocyanins were most stable in the presence of hydrogen peroxide, while a?ai and pigments rich in acylated anthocyanins displayed lower color stability in a temperature-dependent manner. In the presence of ascorbic acid, acylated anthocyanin sources generally had increased color stability. A?ai was recognized for its functional properties for use in food and nutraceutical products.     

Interspecific differences in manganese levels in freshwater bivalves

Vital effects may be important in determining metal levels in bivalves and must be taken into account before the environmental ‘meaning’ of the data may be interpreted. Manganese concentrations in shells and soft tissues of several species of freshwater bivalves from three recent environments in northern Ohio and one archeological site from southern Ohio were determined by neutron activation analysis and show a species effect where Fusconaia flava Mn levels > Anodonta grandis grandis levels ≥ all Lampsilis species levels. Manganese is concentrated by a factor of 2 to 25 in soft tissues compared to shells. In addition, within-taxon variability of Mn concentration is high. The high intraspecies variability points to the necessity of processing many individuals before reliable numbers may be obtained.     

Persistence of phenols in aquatic microcosms receiving chronic inputs of coal-derived oil

The environmental fate of constituent phenols of a coal-derived oil spilled intermittently on water was evaluated in aquatic microcosms. Phenols dissolved rapidly from the oil into the water, and initially accumulated with sequential oil additions. The major process removing phenols from the microcosms was microbial degradation-other processes were negligible in comparison. After phenols attained maximum concentrations in the first 28 days of the study, degradation rates exceeded input rates in all microcosms during the second 28 days the study and total phenol concentrations decreased. Significant differences were apparent in the rates of degradation of various alkylphenol isomers and isomer groups, but no compounds were observed to be refractory. Upon discontinuation of oil inputs at day 56, dissolved phenols disappeared within several weeks. Microcosm exposure history and the presence of other phenol isomers affected the rate of removal of individual isomers, complicating prediction of the rate of removal of individual toxicants.     

Method Dependency in the Measurement of BTEX Levels in Contaminated Soil

Environmental consultants and analytical laboratories are increasingly realizing the importance of analytical method selection and validation for the reliable measurement of soil contamination. Aromatic hydrocarbons (BTEX) is one class of environmentally significant soil contamination for which testing is required by regulatory authorities in most industrialized countries. Unfortunately, in most guidelines there is a lack of direction for the selection of a testing method for BTEX and, in practice, any one of a variety of methods may be employed. The fact that these may not all yield comparable results is a source of much frustration in the industry and there is a paucity of published research into this problem. In a number of carefully controlled experiments, the method dependency of measured BTEX levels in contaminated soil samples has been investigated. Three commonly employed methods, namely, (methanol extraction) purge-and-trap/gas chromatography with mass selective detection (P&T/GCMSD), headspace/GCMSD and dichloromethane (DCM) extraction/gas chromatography with flame ionization detection (GCFID) have been compared in the analysis of 109 gasoline-contaminated soil samples collected from station sites in Melbourne, Australia. Measurable BTEX concentrations were recorded in 92% of the samples using P&T/GCMSD, 59% using DCM/GCFID, and 40% using headspace/GCMSD. Correspondingly, the magnitudes of the recovered concentrations were significantly higher by P&T/GCMSD than by DCM/GCFID, which in turn were significantly higher than the magnitudes determined by headspace/GCMSD. These trends are evident for both clay and sandy soils. These studies clearly demonstrate that, for the three commonly employed methods described, measured BTEX levels are extraction and analytical method dependent in at least two different soil types.     

Phytochemical stability and color retention of copigmented and processed muscadine grape juice

Muscadine (Vitis rotundifolia) grape juice was assessed for color and phytochemical stability as influenced by anthocyanin copigmentation with a water-soluble rosemary extract, fortification with ascorbic acid, and processing by heat or high hydrostatic pressure (HHP). The roles of polyphenolic cofactors in the presence and in the absence of ascorbic acid were assessed as a means to improve the overall processing stability of the juice. Addition of rosemary extract from 0 to 0.4% (v/v) readily formed copigment complexes with anthocyanins and resulted in concentration-dependent hyperchromic shifts from 10 to 27% that corresponded to increased antioxidant activity. The presence of ascorbic acid was generally detrimental to juice quality, especially in the presence of rosemary extract, and resulted in overall anthocyanin, ascorbic acid, and antioxidant activity losses. Although thermal and high-pressure processing methods were detrimental to juice quality, HHP resulted in greater losses after processing, likely due to action from residual oxidase enzymes. Although physicochemical attributes were enhanced by copigmentation with rosemary extract, methods to inactivate residual enzymes should be addressed prior to copigmentation to prevent degradation of anthocyanins in the presence of ascorbic acid.