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Byline: M. Camacho Barron (1), E. Gonzalez de Mejia (1) Keywords: common bean; drought effect; proline metabolism; tepary bean Abstract: There are several mechanisms used by plants for survival in adverse environments such as drought, high temperature and salinity. The objective of this study was to evaluate the drought tolerance of tepary bean as a function of biochemical processes linked to isozyme synthesis and changes in enzymatic activity related to proline metabolism. Mature seeds of common beans var. flor de mayo, Phaseolus vulgaris and tepary beans Phaseolus acutifolius were grown under two water conditions (irrigation and drought), and four levels of urea. Vertical electrophoresis and spectrophotometric techniques were used to evaluate protein patterns, glutamate dehydrogenase (GDH), proline oxidase (PO) and pyrroline-5-carboxylate reductase (P5C reductase) enzyme activities. These enzymes were studied because they are directly related to protein synthesis. Electrophoretic patterns showed more proteins in tepary beans than in common beans with limited irrigation. GDH showed only one isozyme, with a molecular weight between 240 to 270 kDa. A decrease in PO activity was observed in common beans under drought stress with a value of 237 umol/min, in comparison to irrigation conditions of 580 umol/min. GDH and P5C reductase enzymes have had higher activity in common beans than in tepary beans under water stress. There was a significant difference only in glutamate dehydrogenase enzyme with respect to urea level. The results suggest that drought tolerance of tepary beans is due to biochemical processes related to proline metabolic enzymes. Author Affiliation: (1) Mexico, Research and Graduate Group in Food Science, University of Queretaro, Centro Universitario, Cerro de las Campanas, Queretaro, Qro., Mexico Article History: Registration Date: 14/10/2004

A study that analyzed the microbial and chemical composition of the Queso Chihuahua and its histamine and tyramine content is presented. Samples of white cheese found in Chihuahua and Hermosillo, Mexico were examined for bacteriological quality, chemical constitution and amine content. Specimens were stored at 5 to 25 degrees Celsius and then evaluated at 4-day intervals for 12 days. Results show that the Chihuahua cheese had 43.7% fat content; 49.2% protein content, 2.7% salt, 45% water content and a pH level of 5.25. However, there was an increase in amine content during storage. Significant increases in histamine and tyramine concentrations in high temperature storage were also noted.

A research to determine the in vitro influence of phenolic compounds present in aqueous, ethyl acetate, and chloroform extracts of H. sabdariffa on mutagenicity of 1-nitropyrene (1-NP) and also the antiproliferative effect of the extracts on transformed human HeLa cells is discussed. The empirical outcomes propose that H. sabdariffa L. extracts have antimutagenic activity against 1-NP and reduce the proliferation of HeLa cells, may be because of phenolic acid composition.