BIOGENIC AMINE CONTENT AND MICROBIAL CONTAMINATION OF LEAFY VEGETABLES DURING STORAGE AT 5C

Biogenic amine content and microbial contamination of prepacked salad mixtures and the fresh leafy vegetables Chinese cabbage (Brassica pekinensis Rupr.), endive (Cichorium endivia L.), iceberg lettuce (Lactuca sativa var. capitata) and radicchio (Cichorium intybus var. foliosum) were examined during storage at 5C for 6 days. Putrescine, histamine, spermidine, spermine and tyramine were detected in concentrations ranging from 0.1 to 17 μg/g fresh weight. Only putrescine showed a progressive increase during storage, depending on the type of leafy vegetable; its level of increase ranged from 3- to 8-fold, with the most pronounced for Chinese cabbage. A relationship seems to exist between the Enterobacteriaceae population (representing up to 90% of the total microbial numbers determined by plate count methods) and the putrescine concentration.     

Expression of caveolin-1 in rat Leydig cells

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking.
The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules. Caveolin-1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin-1 and 3β-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosinephosphocaveolin-1 antibodies. Caveolin-1 is one of a few proteins with a demonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin-1 in Leydig cells may be related to cholesterol traffic -a rate limiting step in steroid biosynthesis.