Monitoring biodegradation of ethene and bioremediation of chlorinated ethenes at a contaminated site using compound-specific isotope analysis (CSIA)

Chlorinated ethenes are commonly found in contaminated groundwater. Remediation strategies focus on transformation processes that will ultimately lead to nontoxic products. A major concern with these strategies is the possibility of incomplete dechlorination and accumulation of toxic daughter products (cis-1,2-dichloroethene (cDCE), vinyl chloride (VC)). Ethene mass balance can be used as a direct indicator to assess the effectiveness of dechlorination. However, the microbial processes that affect ethene are not well characterized and poor mass balance may reflect biotransformation of ethene rather than incomplete dechlorination. Microbial degradation of ethene is commonly observed in aerobic systems but fewer cases have been reported in anaerobic systems. Limited information is available on the isotope enrichment factors associated with these processes. Using compound-specific isotope analysis (CSIA) we determined the enrichment factors associated with microbial degradation of ethene in anaerobic microcosms (ε = -6.7‰ ± 0.4‰, and -4.0‰ ± 0.8‰) from cultures collected from the Twin Lakes wetland area at the Savannah River site in Georgia (United States), and in aerobic microcosms (ε = -3.0‰ ± 0.3‰) from Mycobacterium sp. strain JS60. Under anaerobic and aerobic conditions, CSIA can be used to determine whether biotransformation of ethene is occurring in addition to biodegradation of the chlorinated ethenes. Using δ(13)C values determined for ethene and for chlorinated ethenes at a contaminated field site undergoing bioremediation, this study demonstrates how CSIA of ethene can be used to reduce uncertainty and risk at a site by distinguishing between actual mass balance deficits during reductive dechlorination and apparent lack of mass balance that is related to biotransformation of ethene.     

Treatment of raw poultry with nonthermal dielectric barrier discharge plasma to reduce Campylobacter jejuni and Salmonella enterica

Nonthermal plasma has been shown to be effective in reducing pathogens on the surface of a range of fresh produce products. The research presented here investigated the effectiveness of nonthermal dielectric barrier discharge plasma on Salmonella enterica and Campylobacter jejuni inoculated onto the surface of boneless skinless chicken breast and chicken thigh with skin. Chicken samples were inoculated with antibiotic-resistant strains of S. enterica and C. jejuni at levels of 10(1) to 10(4) CFU and exposed to plasma for a range of time points (0 to 180 s in 15-s intervals). Surviving antibiotic-resistant pathogens were recovered and counted on appropriate agar. In order to determine the effect of plasma on background microflora, noninoculated skinless chicken breast and thighs with skin were exposed to air plasma at ambient pressure. Treatment with plasma resulted in elimination of low levels (10(1) CFU) of both S. enterica and C. jejuni on chicken breasts and C. jejuni from chicken skin, but viable S. enterica cells remained on chicken skin even after 20 s of exposure to plasma. Inoculum levels of 10(2), 10(3), and 10(4) CFU of S. enterica on chicken breast and chicken skin resulted in maximum reduction levels of 1.85, 2.61, and 2.54 log, respectively, on chicken breast and 1.25, 1.08, and 1.31 log, respectively, on chicken skin following 3 min of plasma exposure. Inoculum levels of 10(2), 10(3), and 10(4) CFU of C. jejuni on chicken breast and chicken skin resulted in maximum reduction levels of 1.65, 2.45, and 2.45 log, respectively, on chicken breast and 1.42, 1.87, and 3.11 log, respectively, on chicken skin following 3 min of plasma exposure. Plasma exposure for 30 s reduced background microflora on breast and skin by an average of 0.85 and 0.21 log, respectively. This research demonstrates the feasibility of nonthermal dielectric barrier discharge plasma as an intervention to help reduce foodborne pathogens on the surface of raw poultry.     

The effects of pre-slaughter pig management from the farm to the processing plant on pork quality

Two experiments (Exp.1, n = 80; Exp.2, n = 144) were conducted to determine the effects of pre-slaughter pig management on pork quality by monitoring blood lactate concentration ([LAC]) during marketing. [LAC] was measured at: (1) baseline at farm, (2) post-loading on truck, (3) pre-unloading after transport, (4) post-unloading at plant, (5) post-lairage, (6) post-movement to stun, and (7) exsanguination. Pearson correlations were used to determine relationships between [LAC] and meat quality. Higher [LAC] post-loading or a greater change in [LAC] during loading resulted in increased 24 h pH (P = 0.002, P = 0.0006, Exp.1; P = 0.0001, P = 0.01, Exp.2, respectively), decreased L* (P = 0.03, P = 0.04; P = 0.001, P = 0.01) and decreased drip loss (P = 0.02, P = 0.12; P = 0.002, P = 0.01). Even though improved handling during loading is important to animal well-being, it will not necessarily translate into improved pork quality.     

Dicistronic regulation of fluorescent proteins in the budding yeast Saccharomyces cerevisiae

Fluorescent proteins are convenient tools for measuring protein expression levels in the budding yeast Saccharomyces cerevisiae. Co‐expression of proteins from distinct vectors has been seen by fluorescence microscopy; however, the expression of two fluorescent proteins on the same vector would allow for monitoring of linked events. We engineered constructs to allow dicistronic expression of red and green fluorescent proteins and found that expression levels of the proteins correlated with their order in the DNA sequence, with the protein encoded by the 5′‐gene more highly expressed. To increase expression levels of the second gene, we tested four regulatory elements inserted between the two genes: the IRES sequences for the YAP1 and p150 genes, and the promoters for the TEF1 gene from both S. cerevisiae and Ashbya gossypii. We generated constructs encoding the truncated ADH1 promoter driving expression of the red protein, yeast‐enhanced Cherry, followed by a regulatory element driving expression of the green protein, yeast‐enhanced GFP. Three of the four regulatory elements successfully enhanced expression of the second gene in our dicistronic construct. We have developed a method to express two genes simultaneously from one vector. Both genes are codon‐optimized to produce high protein levels in yeast, and the protein products can be visualized by microscopy or flow cytometry. With this method of regulation, the two genes can be driven in a dicistronic manner, with one protein marking cells harbouring the vector and the other protein free to mark any event of interest. Copyright © 2009 John Wiley & Sons, Ltd.     

Bronchopulmonary dysplasia: the pulmonary pathologic sequel of necrotizing bronchiolitis and pulmonary fibrosis

A light and electron microscopic study was carried out in 21 infants in whom the pathologic diagnosis of bronchopulmonary dysplasia had been made. All the infants except two had the respiratory distress syndrome at birth, and all 21 had been treated with respirator and oxygen therapy for various periods of time. The pathologic alterations observed in all the infants studied were primarily damage of the bronchial and bronchiolar ciliary apparatus and mucous membranes, severe necrotizing bronchiolitis, and marked bronchiolar and alveolar fibrosis. These changes were more pronounced in infants who survived the longest period of time. Such inflammatory and fibrotic changes are known to predispose to destruction of lung tissue, emphysema, and pulmonary hypertension. Six of these 21 infants developed symptoms and signs of cardiac atrial or ventricular stress, including cor pulmonale, prior to their demise. These infants were among those that survived the longest periods of time, had the longest exposure to supplemental oxygen, and showed histopathologically severe pulmonary fibrosis and emphysema.     

Letter: Electrical method of detecting optimum time to inseminate

Recently translated studies of the electrical resistance of cervical mucus as a test for the optimum time of insemination of agricultural animals are reviewed. The technique involves the measurement of the electrical conductivity of the surface of the mucosa in the vaginal vestibule. Experiments with cows and sows have shown that pregnancy or fertilization rates are considerably higher when mucosal electrical resistance is low at the time of insemination than when resistance is high. It has also been demonstrated in sows that mucosal resistance is higher in pregnant than in nonpregnant animals. Further research into these results is recommended.     

Effect of tinidazole, metronidazole and nitrofurazone on nucleic acid synthesis in Clostridium bifermentans

Coplanar lines of different orientations rotating in depth and viewed in parallel projection may appear to rotate in different directions and reverse independently of each other, or they may appear coplanar and all reverse together. The frequency of the latter "grouped" appearance for lines with an orientation range of 30 degrees was a function of the number of lines in a given space. Grouping was greater for lines converging to an implicit vanishing point and for lines with collinear edges regardless of their orientations. Line length, and by inference, interline separation also had effect of the nature of the response.     

The clinical diagnosis of major congenital abnormalities of the fetal central nervous system

During the ten years between 1965 and 1974, 207 infants with a major congenital abnormality of the central nervous system were born at Mill Road Maternity Hospital, Liverpool; open neural tube defects occurred in 92 per cent of cases. Only cases of anencephaly were frequently diagnosed clinically before labour and this was rarely so for spina bifida alone. Only 11 patients (5-3 per cent) had previously been delivered of an affected infant. The routine screening of pregnant patients is briefly discussed.