The main extracellular matrix binding component of the dystrophin-glycoprotein complex, ␣-dystroglycan (␣-DG), which was originally isolated from rabbit skeletal muscle, is an extensively O-glycosylated protein. Previous studies have shown ␣-DG to be modified by both O-GalNAc-and O-mannose-initiated glycan structures. O-Mannosylation, which accounts for up to 30% of the reported O-linked structures in certain tissues, has been rarely observed on mammalian proteins. Mutations in multiple genes encoding defined or putative glycosyltransferases involved in O-mannosylation are causal for various forms of congenital muscular dystrophy. Here, we explore the glycosylation of purified rabbit skeletal muscle ␣-DG in detail. Using tandem mass spectrometry approaches, we identify 4 O-mannose-initiated and 17 O-GalNAc-initiated structures on ␣-DG isolated from rabbit skeletal muscle. Additionally, we demonstrate the use of tandem mass spectrometry-based workflows to directly analyze glycopeptides generated from the purified protein. By combining glycomics and tandem mass spectrometry analysis of 91 glycopeptides from ␣-DG, we were able to assign 21 different residues as being modified by O-glycosylation with differing degrees of microheterogeneity; 9 sites of O-mannosylation and 14 sites of O-GalNAcylation were observed with only two sites definitively exhibiting occupancy by either type of glycan. The distribution of identified sites of O-mannosylation suggests a limited role for local primary sequence in dictating sites of attachment.Defects in protein glycosylation related to human disease were first reported in the 1980s, and since then, about 40 various types of congenital disorders of glycosylation have been reported (1). The term congenital disorders of glycosylation was first used to describe alterations of the N-glycosylation pathway and was later expanded to include the O-glycosylation pathways (1-3). The importance and complexity of O-linked glycosylation have only recently begun to be appreciated (1, 3, 4). In particular, mutations in genes encoding (putative) glycosyltransferases, which catalyze the addition and extension of O-linked mannose-initiated glycans, have garnered increased attention in the last decade given that they are causative for several forms of congenital muscular dystrophy (5, 6).The most common forms of O-glycosylation on secretory proteins are the mucin-like O-GalNAc structures that are initiated by polypeptide N-␣-acetylgalactosaminyltransferases in the endoplasmic reticulum-Golgi intermediate compartment and/or early cis-Golgi (7). Additionally, other O-linked structures are initiated with alternative monosaccharides, such as O-mannose, O-glucose, O-fucose, O-xylose, and O-GlcNAc onSer/Thr residues and the O-galactose modification of hydroxylysine residues in collagen domains (4). The diversity of O-mannosylated proteins in mammals, although quite abundant in some tissues (ϳ30% of O-glycans released from mouse brains (8)), has not been well characterized. The only clearly identified mamma...

Pasteurized apple cider produced in Georgia was surveyed for patulin. Levels from 244-3993 p,g patulin/L cider were found. Eight high temperature-short time (HTST) treatments (60", 70". 80", and 90°C for 10 set; 90°C for 20, 40, 80, and 160 set) and one batch treatment (90°C for 10 min) were used to determine the stability of patulin in pasteurized cider. The 60", 80", and 90°C HTST treatments and the batch pasteurization significantly reduced the patulin level, but did not completely destroy the toxin. Storage of the cider had no effect on the patulin level.

High pressure liquid chromatography was used to evaluate the effects of several naturally occurring food components (selenium, vitamins A, E, B6 and C) on the in vitro metabolism of aflatoxin B, (AFB,). AFB, was incubated with a liver microsomal enzyme metabolizing system with varying concentrations of each nutrient. The following nutrients and levels either inhibited or reduced the metabolism of AFB,: sodium selenite (25 pg/mL), d-cY-tocopherol(25, 250 and 2500 FglmL), pyridoxine hydrochloride (2.5 PglmL), L-ascorbic acid (25 and 2500 pg/mL) and mixture containing 500 p,g/mL of each chemical. Retinol acetate at levels of 2.5 and 25 pg/mL increased the level of AFB 1 metabolized.