Sequence analysis of a 14·6 kb DNA fragment of Saccharomyces cerevisiae chromosome VII reveals SEC27, SSM1b,a putative S-adenosylmethionine-dependent enzyme and six new open reading frames

The nucleotide sequence of a fragment from the left arm of Saccharomyces cerevisiae chromosome VII has been determined. Analysis of the 14,607 bp DNA segment reveals nine open reading frames (ORFs) longer than 300 bp. G2827 is the SEC 7 gene, an essential coatomer complex subunit. G2834 encodes SSM1b, a ribosomal protein. The G2838 product shows homology to hypothetical yeast proteins, YIF0 and YE09, of unknown function. The G2830 product shows homology with the cell division protein FtsJ from Escherichia coli, with two hypothetical proteins from yeast, YCF4 and YBR1, and with R74.7, a hypothetical protein from Caenorhabditis elegans. Two of the ORFs are completely internal to longer ones and a third is partially embedded in G2850. The remaining ORFs give no significant homology with proteins in the databases. The sequence has been deposited at the EMBL database under Accession Number X92670.     

Physical aging in polymers: Comparison of two ways of determining narayanaswamy's parameter

In this work, we have investigated by differential scanning calorimetry the enthalpy relaxation of two poly[methyl(α-n-alkyl)acrylates] in which it is possible to change the length of the two alkyl chains. In particular, we have evaluated the Narayanaswamy parameter, which controls relative contribution of temperature and of structure to the relaxation times, by two methods: Grenet's method (GM) and the peak-shift method (PSM). The data obtained show that both methods lead to equivalent results. Nevertheless, PSM requires fewer experiments than GM, and PSM appears to be more practical. The results obtained on the two acrylates show that the parameter x increases with the lateral chain length, that is to say, that the temperature effects increase as the length of the alkyl chain is increased.     

Fetal Undernutrition Modifies Vascular RAS Balance Enhancing Oxidative Damage and Contributing to Remodeling

Fetal stress is known to increase susceptibility to cardiometabolic diseases and hypertension in adult age in a process known as fetal programming. This study investigated the relationship between vascular RAS, oxidative damage and remodeling in fetal programming. Six-month old Sprague-Dawley offspring from mothers that were fed ad libitum (CONTROL) or with 50% intake during the second half of gestation (maternal undernutrition, MUN) were used. qPCR or immunohistochemistry were used to obtain the expression of receptors and enzymes. Plasma levels of carbonyls were measured by spectrophotometry. In mesenteric arteries from MUN rats we detected an upregulation of ACE, ACE2, AT₁ receptors and NADPH oxidase, and lower expression of AT₂, Mas and MrgD receptors compared to CONTROL. Systolic and diastolic blood pressure and plasma levels of carbonyls were higher in MUN than in CONTROL. Vascular morphology evidenced an increased media/lumen ratio and adventitia/lumen ratio, and more connective tissue in MUN compared to CONTROL. In conclusion, fetal undernutrition indices RAS alterations and oxidative damage which may contribute to the remodeling of mesenteric arteries, and increase the risk of adverse cardiovascular events and hypertension.     

Safety Assessment of Fresh and Processed Seafood Products by MALDI-TOF Mass Fingerprinting

Foodborne intoxications caused by the consumption of fish and other products of marine origin contaminated with bacterial pathogens are an ever-present threat, either due to bacteria and/or its metabolites. In addition, the rapid spoilage of seafood due to microbial activity, results in high economic losses. The development of the microbiota in seafood products depends on the microbiological ambience of capture, processing and storage, and the applied preservation method. Thus, pathogenic and spoilage bacterial species in seafood may come from the indigenous microbiota of the aquatic ambience or are introduced by contamination during processing. Rapid and accurate bacterial species identification is essential for an effective control program to ensure safety and quality of either processed or minimally processed seafood. In the present work, matrix-assisted laser desorption ionization-time of flight mass spectrometry was successfully applied to identify 26 bacterial strains isolated from fresh fish and processed seafood samples. The approach was based on the comparison of unknown spectra to a reference spectral library and demonstrated to be a fast and accurate technique for bacterial species differentiation, which can be used for the rapid identification of foodborne pathogens and spoilage bacteria potentially present in products of marine origin.     

High-Pressure Treatment and Freezing of Raw Goat Milk Curd for Cheese Manufacture: Effects on Cheese Characteristics

High-pressure treatment of raw goat milk curd was investigated as an alternative to thermal treatment of milk in cheese manufacture, and curd freezing as a procedure to surmount the seasonality of goat milk production. Experimental cheeses were made by mixing (70:30) fresh cow milk curd with frozen curd from pasteurized goat milk (PGC), frozen curd from raw goat milk (RGC), or frozen pressurized curd from raw goat milk (PRGC). Control cheese was made from a mixture (70:30) of pasteurized cow and goat milk. RGC cheese showed the highest counts of staphylococci, Gram-negative bacteria and coliforms, whereas PRGC cheese had maximum aminopeptidase activity, esterase activity, and overall proteolysis. Control cheese exhibited the highest dry matter content and peptide levels, the lowest concentration of free amino acids, the highest concentration of volatile compounds such as free fatty acids, alcohols and esters, and the firmest texture. Differences in sensory characteristics between experimental and control cheeses were of minor importance. High-pressure treatment of curd allowed the production of cheese of bacteriological quality similar to that of control cheese made using pasteurized milk, while curd freezing did not alter the sensory characteristics of experimental cheeses with respect to control cheese.     

Antioxidant properties,radical scavenging activity and biomolecule protection capacity of flavonoid naringenin and its glycoside naringin: a comparative study

BACKGROUND: This study was designed to evaluate and compare antioxidant capacity and radical scavenging activity of naringin and its aglycone by different in vitro assays. The effects of flavanones on lipid peroxidation, glutathione (GSH) oxidation and DNA cleavage were also assessed. RESULTS: The results showed that naringenin exhibited higher antioxidant capacity and hydroxyl and superoxide radical scavenger efficiency than naringin. Our results evidenced that glycosylation attenuated the efficiency in inhibiting the enzyme xanthine oxidase and the aglycone could act like a more active chelator of metallic ions than the glycoside. Additionally, naringenin showed a greater effectiveness in the protection against oxidative damage to lipids in a dose‐dependent manner. Both flavanones were equally effective in reducing DNA damage. However, they show no protective effect on oxidation of GSH. CONCLUSION: The data obtained support the importance of characterizing the ratio naringin/naringenin in foods when they are evaluated for their health benefits. Copyright © 2010 Society of Chemical Industry     

Chemical analysis and significance of heterocyclic aromatic amines

 Levels of known heterocyclic amines vary from undetectable in many meats sold in fast food restaurants, to over 10 ng/g for meats prepared in restaurants that cook food to order, to hundreds of nanograms per gram for some meats cooked under certain home or laboratory conditions. To simulate the dry reactions that seem to occur at the meat surface we developed a model system to mimic these processes. Mixtures of free amino acids, creatinine and glucose, simulating the composition of beef or chicken, heated at 200  °C, form eight heterocyclic amines. Besides the commonly found 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-1,6-dimethylimidazo[4,5-b]pyridine, 2-amino-1,5,6-trimethylimidazo[4,5-b]pyridine and 2-amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b]pyridine were also found. The calculated risk of consumption of heterocyclic amines is determined by the dietary dose, the extrapolation of carcinogenic potencies from rodents to humans, and the extrapolation of high rodent doses to low human exposures. Results suggest that DNA binding is linear with dose, but that the human DNA forms more adducts per unit dose than that of the rat. Altogether, the risk appears to be equivalent to that for many carcinogens that are regulated. Received: 23 April 1998     

Chemical analysis and significance of heterocyclic aromatic amines

 Levels of known heterocyclic amines vary from undetectable in many meats sold in fast food restaurants, to over 10 ng/g for meats prepared in restaurants that cook food to order, to hundreds of nanograms per gram for some meats cooked under certain home or laboratory conditions. To simulate the dry reactions that seem to occur at the meat surface we developed a model system to mimic these processes. Mixtures of free amino acids, creatinine and glucose, simulating the composition of beef or chicken, heated at 200  °C, form eight heterocyclic amines. Besides the commonly found 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, 2-amino-1,6-dimethylimidazo[4,5-b]pyridine, 2-amino-1,5,6-trimethylimidazo[4,5-b]pyridine and 2-amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b]pyridine were also found. The calculated risk of consumption of heterocyclic amines is determined by the dietary dose, the extrapolation of carcinogenic potencies from rodents to humans, and the extrapolation of high rodent doses to low human exposures. Results suggest that DNA binding is linear with dose, but that the human DNA forms more adducts per unit dose than that of the rat. Altogether, the risk appears to be equivalent to that for many carcinogens that are regulated. Received: 23 April 1998     

Involvement of Clostridium gasigenes and C. algidicarnis in 'blown pack' spoilage of Brazilian vacuum-packed beef

The objectives of this study were to isolate psychrotrophic clostridia from Brazilian vacuum-packed beef cuts (spoiled or not) and to identify the isolates by using 16S rRNA gene sequencing. Anaerobic psychrotrophic microorganisms were also enumerated and samples were collected to verify the incidence of psychrotrophic clostridia in the abattoir environment. Vacuum-packed beef cuts (n = 8 grossly distended and n = 5 non-spoiled) and environmental samples were obtained from a beef packing plant located in the state of São Paulo, Brazil. Each sample was divided in three subsamples (exudate, beef surface and beef core) that were analyzed for vegetative forms, total spore-forming, and sulfide reducing spore-forming, both activated by alcohol and heat. Biochemical profiles of the isolates were obtained using API20A, with further identification using 16S rRNA gene sequencing. The growth temperature and the pH range were also assessed. Populations of psychrotrophic anaerobic vegetative microorganisms of up to 10¹⁰ CFU/(g, mL or 100 cm²) were found in ‘blown pack’ samples, while in non-spoiled samples populations of 10⁵ CFU/(g, CFU/mL or CFU/100cm²) was found. Overall, a higher population of total spores and sulfide reducing spores activated by heat in spoiled samples was found. Clostridium gasigenes (n = 10) and C. algidicarnis (n = 2) were identified using 16S rRNA gene sequencing. Among the ten C. gasigenes isolates, six were from spoiled samples (C1, C2 and C9), two were isolated from non-spoiled samples (C4 and C5) and two were isolated from the hide and the abattoir corridor/beef cut conveyor belt. C. algidicarnis was recovered from spoiled beef packs (C2). Although some samples (C3, C7, C10 and C14) presented signs of ‘blown pack’ spoilage, Clostridium was not recovered. C. algidicarnis (n = 1) and C. gasigenes (n = 9) isolates have shown a psychrotrophic behavior, grew in the range 6.2-8.2. This is the first report on the isolation of psychrotrophic Clostridium (C. gasigenes and C. algidicarnis) in Brazil. This study shows that psychrotrophic Clostridium may pose a risk for the stability of vacuum-packed beef produced in tropical countries during shelf-life and highlights the need of adopting control measures to reduce their incidence in abattoir and the occurrence of ‘blown pack’ spoilage.