Porcine oxymyoglobin and lipid oxidation in vitro

The present study was carried out to investigate the effect of dietary α-tocopherol supplementation on porcine oxymyoglobin (OxyMb) and lipid oxidation (TBARS) in model lipid systems, and to determine the influence of 4-hydroxynonenal (4-HNE), a secondary product of lipid oxidation, on porcine OxyMb stability. Porcine metmyoglobin (MetMb) formation was greater in the presence of 4-HNE than the control (P<0.05). Western blot analyses confirmed the covalent modification of myoglobin (Mb) histidine residues by 4-HNE. When combined with microsomes, both equine and porcine OxyMb oxidation increased with time of incubation, and was greater at 37 than at 25?°C (P<0.05). Lower TBARS values were observed in microsomes prepared from vitamin E-supplemented than control pork livers (P<0.05). α-Tocopherol concentration did not affect OxyMb oxidation in microsomes at 25 or 37?°C (P>0.05). These results differ from those observed with beef muscle microsomes where both OxyMb and lipid oxidation were delayed with elevated α-tocopherol levels. These results suggest that the factors affecting Mb and lipid oxidation interactions may be species-dependent.     

Effect of ethanol on the growth of Clostridium botulinum

Model broth studies were carried out to investigate the effect of ethanol on the growth of proteolytic (group I) strains of Clostridium botulinum. Ethanol extended the pathogen's lag phase, decreased its exponential growth rate, and decreased its final level of growth in the stationary phase. In all cases, botulinum neurotoxin production was associated with growth. Micrographs of C. botulinum cultures grown at 37 degrees C in trypticase peptone glucose yeast extract (TPGY) broths containing 2 and 4% ethanol showed elongation of vegetative cells and interference with cell division. The inhibition of growth and toxin production at the ethanol level predicted (5.5%, wt/wt) was confirmed by microscopy and by the mouse bioassay. A subsequent study was carried out to determine the combined effect of ethanol (0 to 8% [wt/wt]), water activity (aw; 0.953 to 0.997), and pH (6.2 to 8.2) on the probability of the growth of and neurotoxin production by proteolytic strains of C. botulinum (10(3) spores per ml). Growth and neurotoxin production occurred in 1 to 3 days in TPGY broths without ethanol (0%) and in 2 to 4 days in broths containing 2% ethanol regardless of the aw or pH levels (P < 0.005). Growth and neurotoxin production were delayed by an ethanol concentration of 4% ethanol and completely inhibited by a concentration of 6%. At an ethanol concentration of 4%, the probability of growth and toxin production over 365 days (Pt) was influenced by aw and pH. After 365 days, the maximum probability of growth and toxin production (Pmax) was 1 for all but one combination. However, tau, the time it took for 50% of all eventually positive replicates for any given combination of barriers to show growth and/or turbidity, ranged from <3 to 229 days. All tubes of TPGY broths that showed no growth after 365 days were subcultured in fresh TPGY broths. In all cases, growth and toxin production occurred within 24 h at 37 degrees C, indicating the reversible (sporostatic and/or bacteriostatic) effect of ethanol on C. botulinum.     

Regulation of ovarian function by the TGF-beta superfamily and follistatin

The role of follistatin as an activin-binding protein has dominated the study of this molecule for the last 10 years. However, there is emerging evidence that follistatin has a role in modulating the biology of other members of the transforming growth factor beta (TGF-beta) superfamily. This review summarizes the current concepts encompassing follistatin biochemistry as well as molecules with which it is functionally associated. Moreover, the importance of the two follistatin isoforms (follistatin-288 and follistatin-315) is discussed with particular emphasis on the regulation of the ovary. In addition to activin, this review discusses the functions of other members of the TGF-beta superfamily, for example growth differentiation factor 9 (GDF-9), bone morphogenetic protein 15 (BMP-15), BMP-6, BMP-4 and BMP-7, in the ovary, and the potential interactions between follistatin and these growth factors. The complex network of TGF-beta superfamily growth factor members involved in the modulation of ovarian function and the interactions of follistatin with these proteins is highlighted.     

Initial characterization of humic acids using liquid chromatography at the critical condition followed by size-exclusion chromatography and electrospray ionization mass spectrometry

Structural information on humic acids is difficult to obtain because of the heterogeneity of the acids. Herein liquid chromatography at the critical condition, LCCC, is used to provide a sorting mechanism for the diverse types of molecules contained in humic acids. The critical condition of polymers that are believed to model some subunit of the humic acid is determined. Humic acids from three different terrestrial sources (soil, compost, and peat) are then separated under these chromatographic conditions. The portion of the humic acid that has structure similar to that of the model polymer elutes at the retention volume of the critical condition of the model. Next, fractions are collected and further characterized. This detailed characterization includes high-efficiency size-exclusion chromatography and electrospray mass spectrometry. The size-exclusion chromatograms of the fractions were found to be markedly different from that of the original humic acid sample. This is strong evidence that the LCCC separation mechanism is different from size fractionation. The mass spectra of the humic acid fractions were also markedly different from those of the bulk humic acids previously reported. The mass spectra of specific fractions collected had repeating clusters of m/z values, which is more evidence that the critical condition separation is a powerful sort function.