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Warner-Bratzler shear force (WBSF) and % intramuscular fat content (IMF) are objective meat quality measurements that are significantly correlated with aspects of palatability such as tenderness, flavour and juiciness. Using cDNA microarrays, Musculus longissimus transcriptomic profiles at slaughter were compared in samples displaying lower or higher IMF (n=8) and WBSF values on day 1 post mortem (n=8). 101 identified genes were differentially expressed in relation to WBSF, while 160 genes were associated with differences in IMF. Reduced expression of protein synthesis genes and enhanced expression of genes involved in protein degradation were associated with lower WBSF values on day 1. Pathways including oxidative phosphorylation and the citrate cycle were significantly associated with higher IMF. Many lipid oxidation and fatty acid metabolism pathway genes were down-regulated in high IMF tissue, suggesting a suppression of fatty acid turnover in muscle with higher fat content. Identified genes provide targets for the discovery of novel genetic variation influential on pork palatability., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Fecal indicator bacteria concentrations measured in the surf zone off Huntington Beach, CA from July 1998-December 2001 were analyzed with respect to their spatial patterns along 23 km of beach, and temporal variability on time scales from hourly to fortnightly. The majority of samples had bacterial concentrations less than, or equal to, the minimum detection limit, but a small percentage exceeded the California recreational water standards. Areas where coliform bacteria exceeded standards were more prevalent north of the Santa Ana River, whereas enterococci exceedances covered a broad area both north and south of the river. Higher concentrations of bacteria were associated with spring tides. No temporal correspondence was found between these bacterial events and either the timing of cold water pulses near shore due to internal tides, or the presence of southerly swell in the surface wave field. All three fecal indicator bacteria exhibited a diel cycle, but enterococci rebounded to high nighttime values almost as soon as the sun went down, whereas coliform levels were highest near the nighttime low tide, which was also the lower low tide.

Receptor-mediated cell-extracellular matrix (ECM) interactions are critical regulators of cell survival, and perturbing these signaling pathways can disrupt cellular differentiation and function in a variety of tissues, including the mammary gland. One such receptor is the cell surface-associated, long isoform of beta1,4-galactosyltransferase I (GalT I). Deletion of long GalT I leads to increased mammary ductal branching morphogenesis [Dev. Biol., 244 (2002) 114]. Here, we show that this expansion in the mammary epithelial (ME) cell compartment is accomplished through decreased apoptosis during pregnancy and involution. Decreased apoptosis during involution is concomitant with delayed alveolar collapse, persistent expression of the milk protein gene alpha-lactalbumin and delayed expression of genes associated with the tissue-remodeling phase of involution. Using 3-dimensional in vitro cultures, we show that the decrease in apoptosis is dependent on laminin 1, a ligand for surface GalT I, suggesting that surface GalT I negatively influences ECM-dependent cell survival, a novel function for an ECM receptor. In the best-studied examples, ECM promotes survival through integrin receptor-mediated activation of focal adhesion kinase (FAK). Aggregation of surface GalT I also activates FAK, therefore, we asked if FAK activation was altered in ME from long GalT I null mice. Activated FAK was appropriately localized to focal adhesions in long GalT I null ME. However, FAK activation was constitutively reduced 4.5-fold in long GalT I nulls relative to wild type. Expression of the integrin beta1 subunit was not affected by loss of long GalT I. Collectively, these results suggest that surface GalT I might negatively regulate ME cell survival by linking integrin-independent FAK activation to apoptotic rather than survival signaling events.

Lysyl oxidase levels were estimated in rat tissues using an enzyme-linked immunosorption assay (ELISA) and a functional assay standardized against known amounts of purified lysyl oxidase. High concentrations of lysyl oxidase (> or = 150 micrograms/g of tissue or packed cells) were detected in connective tissues, such as tendon and skin. Values for aorta, kidney, lung and liver ranged from 30 to 150 micrograms/g of tissue; values for skeletal muscle and diaphragm were < 30 micrograms/g tissue. Purified rat skin lysyl oxidase catalyzed the release of 50-100 Bq of tritium per micrograms enzyme in assays that used 3H-elastin-rich substrates. In dense connective tissues, good agreement was obtained for the values from ELISA and those derived from measurements of functional activity in aorta, lung, skin and tendon (r2 > 0.9). When egg white-based experimental diets containing 2 or 10 micrograms/g added copper were fed to weanling rats, values for skin lysyl oxidase functional activity in the group fed 2 micrograms/g added copper were one-third to one-half the values for skin lysyl oxidase functional activity in rats fed 10 micrograms/g copper. This reduction in lysyl oxidase activity, however, had minimal effect on indices of collagen maturation in rat skin, e.g., collagen solubility in neutral salt and dilute acid or the levels of acid stable cross-links. Moreover, copper deficiency did not influence the steady-state levels of lysyl oxidase specific mRNA in rat skin or the apparent amounts of lysyl oxidase in rat skin as determined by ELISA. These observations underscore that the concentration of lysyl oxidase is relatively high in dense corrective tissues, and although decreasing dietary copper influences functional activity, there is little apparent effect on the production of lysyl oxidase protein.

The synthesis and degradation pathways for individual proteins and functional peptides often involve numerous co- and post-translational modifying steps. This review focuses on the diversity of such reactions. The reactions are organized into functional categories. An overall goal is to highlight post-translational events as often having the same importance to functional protein production as the transcriptional and translational events that initiate their synthesis.

Menkes syndrome in humans is an X-linked disorder characterized in part by abnormal copper transport, cellular copper sequestration, and defective crosslinking of collagen and elastin. A decrease in the functional activity of lysyl oxidase, a cuproenzyme, is thought in part to be responsible for the decreased crosslinking of collagen and elastin. It has also been suggested that low levels of lysyl oxidase activity may occur secondarily to disturbances in intracellular copper translocation and consequently impaired incorporation of copper into lysyl oxidase. Herein, we examine the expression and accumulation of selected extracellular matrix proteins in fibroblasts from a Menkes patient, as well as fibroblasts from the tortoiseshell (MoTo/y) mouse. The MoTo mutation is an allele of the mottled (Mo) locus, which is considered to be a murine analog of the human Menkes locus. In both Menkes and tortoiseshell fibroblasts, levels of lysyl oxidase mRNA transcripts were less than 15% of levels for corresponding controls. The level of elastin mRNA transcripts was also markedly lower in both cell lines in comparison to controls. In contrast, the levels of procollagen Type I mRNA were similar or enhanced in Menkes and MoTo/y fibroblasts compared to their respective controls. Consequently, we conclude that the connective tissue defects associated with Menkes syndrome and those occurring in mottled mouse mutants involve more than abnormal copper utilization in the formation of lysyl oxidase holoenzyme. Based on the present studies in cell culture, the production of essential enzymes and matrix proteins, such as lysyl oxidase and elastin, appear to be altered at the level of transcription or mRNA turnover.

We previously reported differences in protein and carbohydrate selection patterns in post-weanling rats fed beef tallow or soybean oil-based diets. Two experiments were designed to determine the characteristic of the dietary fat which mediates the selection behavior. For each experiment, dietary fat was 20% (w/w) of diets and fatty acid profiles were obtained by blending fat sources. Rats were randomly assigned to diets (24% protein, 40% carbohydrate) which varied only in fatty acid composition. After 2 weeks, rats selected from 2 diets with the fat composition previously fed, but varying in their protein and carbohydrate composition (55% protein, 4% carbohydrate and 5% protein, 61% carbohydrate). Experiment 1 was designed to test the effect of relative (omega 6: omega 3 ratios of 1 and 20) and absolute (15% or 4% omega 6, 0.7% or 0.2% omega 3) differences in essential fatty acids on macronutrient selection patterns. Differences in dietary essential fatty acids had no effect on energy intake or the proportion of energy consumed as protein and carbohydrate. Experiment 2 examined the effect of differences in the level of saturated fat (3-10% diet (w/w] on protein and carbohydrate selection. Animals selecting from diets with higher levels of saturated fat consumed more energy as protein and less as carbohydrate than rats selecting from diets with lower levels of saturated fat (p less than 0.0001). Regression analysis was used to examine the relationship between percent protein or carbohydrate energy and classes of dietary fat. The strongest relationship existed between percent dietary saturated fat and percent protein or carbohydrate energy (p less than 0.0001). Polyunsaturated:saturated fat ratio was also weakly associated with percent protein and carbohydrate energy (p less than 0.05). Polyunsaturated, monounsaturated, omega 6 and omega 3 fatty acids were not significantly related to percent protein or carbohydrate energy. These results indicated that protein and carbohydrate selection patterns are altered in response to qualitatively different dietary fatty acids, and that the amount of saturated fat in the diet is the important characteristic of dietary fat mediating the behavioral alteration.

We previously showed changes in protein and carbohydrate selection in response to qualitative differences in dietary fat. Alterations in macronutrient selection were specifically related to changes in dietary saturated fat, but not to relative or absolute differences in dietary essential fatty acids. Three experiments were conducted to determine if changes in specific fatty acids in bulk phase neural membranes were associated with differences in macronutrient selection. For each experiment, specific fatty acid profiles were achieved by blending dietary fat sources. Rats consumed 20% (w/w) fat diets varying only in their fatty acid composition. After 2 weeks, rats were challenged with a selection paradigm. Each experiment showed a significant effect of dietary fat on neural membrane fatty acid composition (p less than 0.05) and alterations in individual fatty acids were correlated with changes in dietary fatty acids (p less than 0.05). However, dietary fat had no consistent effect with respect to which particular neural membrane fatty acids were modified, and there was no correlation between changes in specific membrane fatty acids and macronutrient selection. These findings suggest that alteration of specific fatty acids in bulk phase neural membranes do not mediate macronutrient selection behavior.

In a prospective protocol, plasma tocopherols, selenium (Se), Se-dependent glutathione peroxidase, platelet aggregation and erythrocyte hemolysis were measured in 23 control subjects, and 15 patients receiving total parenteral nutrition (TPN), before and after 2 wk of TPN unsupplemented with vitamin E and Se. The results indicate that short-term TPN did not alter status of these nutrients. However, TPN patients had significantly lower plasma levels of Se (p less than 0.01) and alpha-tocopherol (p less than 0.01) relative to control subjects. Low plasma levels, with no attendant decrease in function, suggest a marginal depletion. In view of this, and considering the low amount of vitamin E and Se supplied by the TPN solutions, supplementation with these nutrients is recommended.

Our previous work showed that rats consuming 20% (wt/wt) lard diets selected more protein and less carbohydrate than did rats fed 20% (wt/wt) soybean oil diets. To determine if this effect is specific to saturated fat source and to measure changes in fatty acid composition of synaptosomal phospholipids, male Wistar rats were fed a 20% (wt/wt) soybean oil or tallow diet with 24% protein and 48% carbohydrate for 2 wk. Rats then self-selected from two diets with the same fat previously fed but different protein and carbohydrate composition (5% protein, 67% carbohydrate and 55% protein, 17% carbohydrate). Tallow-fed rats selected more protein and less carbohydrate than did soybean oil-fed rats. Dietary fat also affected fatty acid composition of synaptosomal phospholipids, phosphatidylcholine being most affected and phosphatidylinositol most resistant. Later studies determined if selection differences were due to taste. When rats self-selected without prior exposure to diets, tallow-fed rats selected more protein and less carbohydrate than did soybean oil-fed rats during the last 2 wk but not the first 2 wk. When rats selected from diets with identical protein and carbohydrate composition but different dietary fat, rats consumed slightly greater amounts of the tallow diet at each protein level. The relative intake of tallow and soybean oil diets, however, did not vary significantly with dietary protein treatment. These results confirm that rats fed saturated fat diets select more protein and less carbohydrate than do rats fed polyunsaturated fat diets and suggest this difference is not due to taste factors.