Photon capture by a rhodopsin pigment molecule induces 11-cis to all-trans isomerization of its retinaldehyde chromophore. To restore light sensitivity, the alltrans-retinaldehyde must be chemically re-isomerized by an enzyme pathway called the visual cycle. Rpe65, an abundant protein in retinal pigment epithelial (RPE) cells and a homolog of ␤-carotene dioxygenase, appears to play a role in this pathway. Rpe65 ؊/؊ knockout mice massively accumulate all-trans-retinyl esters but lack 11-cis-retinoids and rhodopsin visual pigment in their retinas. Mutations in the human RPE65 gene cause a severe recessive blinding disease called Leber's congenital amaurosis. The function of Rpe65, however, is unknown. Here we show that Rpe65 specifically binds alltrans-retinyl palmitate but not 11-cis-retinyl palmitate by a spectral-shift assay, by co-elution during gel filtration, and by co-immunoprecipitation. Using a novel fluorescent resonance energy transfer (FRET) binding assay in liposomes, we demonstrate that Rpe65 extracts all-trans-retinyl esters from phospholipid membranes. Assays of isomerase activity reveal that Rpe65 strongly stimulates the enzymatic conversion of all-trans-retinyl palmitate to 11-cis-retinol in microsomes from bovine RPE cells. Moreover, we show that addition of Rpe65 to membranes from rpe65 ؊/؊ mice, which possess no detectable isomerase activity, restores isomerase activity to wild-type levels. Rpe65 by itself, however, has no intrinsic isomerase activity. These observations suggest that Rpe65 presents retinyl esters as substrate to the isomerase for synthesis of visual chromophore. This proposed function explains the phenotype in mice and humans lacking Rpe65.Light perception in vertebrates is mediated by a group of G protein-coupled receptors called the opsins. Most opsin pigments contain 11-cis-retinaldehyde (11cRAL) 1 as the light-absorbing chromophore. Absorption of a photon induces 11-cis to all-trans isomerization of the chromophore, resulting in the activated species, metarhodopsin II. After a brief period, metarhodopsin II decays to yield apo-rhodopsin and free alltrans-retinaldehyde (atRAL). Before light sensitivity of the pigment can be restored, the atRAL must be chemically re-isomerized to 11cRAL by a metabolic pathway called the visual cycle. Most steps in this pathway take place within cells of the retinal pigment epithelium (RPE) adjacent to the photoreceptors. The key step in this pathway is all-trans to 11-cis re-isomerization of the retinoid, which is catalyzed by an enzyme activity called isomerohydrolase (IMH). IMH has been shown to use fatty acyl esters of retinol as a substrate (1, 2), harnessing the energy of ester hydrolysis [⌬G ϭ Ϫ5 kcal/mol (3)] for the endothermic conversion of all-trans-retinol (atROL) to 11-cis-retinol (11cROL) (ϩ4.1 kcal/mol, Ref. 4). IMH has never been purified or cloned. Leber's congenital amaurosis (LCA) is a severe and relatively common autosomal recessive disease that results in blindness at birth. LCA is frequently caused by mutations in the RP...

Background/Objectives Poor appetite in older adults leads to sub-optimal food intake and increases the risk of undernutrition. The impact of poor appetite on food intake in older adults is unknown. The aim of this study was to examine the differences in food intake among older community-dwelling adults with different reported appetite levels. Design Cross-sectional analysis of data from a longitudinal prospective study. Setting Health, Aging, and Body Composition Study, USA. Participants 2,597 community-dwelling adults aged 70–79. Measurements A semi-quantitative interviewer-administered 108-item food frequency questionnaire to estimate dietary intake. Poor appetite was defined as the report of a moderate, poor or very poor appetite in the past month and was compared with good or very good appetite. Results The mean age of the study sample was 74.5 ± 2.8 years, 48.2% were men, 37.7% were black and 21.8% reported a poor appetite. After adjustment for total energy intake and potential confounders (including biting/chewing problems), participants with a poor appetite had a significantly lower consumption of protein and dietary fiber, solid foods, protein rich foods, wholegrains, fruits and vegetables, but a higher consumption of dairy foods, fats, oils, sweets and sodas compared to participants with very good appetite. In addition, they were less likely to report consumption of significant larger portion sizes. Conclusion Older adults reporting a poor appetite showed a different dietary intake pattern compared to those with (very) good appetite. Better understanding of the specific dietary intake pattern related to a poor appetite in older adults can be used for nutrition interventions to enhance food intake, diet variety and diet quality.

T-cell lymphomas induced by Moloney murine leukemia virus frequently have proviruses integrated at the Mlvi-4 and Mlvi-l loci, which map approximately 30 and 270 kilobases 3' of the promoter region of the Myc protooncogene, respectively. Provirus insertion in these loci is responsible for the activation of adjacent genes. To determine whether Myc expression was also affected by these provirus insertions, we constructed T-cell hybrids between two rat thymic lymphomas containing a provirus in Mlvi-4 or Mlvi-I and the murine T-cell lymphoma line BW5147. These hybrids segregated the provirus-containing rearranged alleles from the normal nonrearranged alleles of Mlvi-4 and Mlvi-), and they carried an intact copy of rat Myc. Using an S1 nuclease protection assay, we observed that the expression of the rat Myc cosegregated with the rearranged Mlvi-4 or Mlvi-I locus. However, provirus insertion in these loci had no effect on promoter utilization or on the expression of the murine Myc locus. We conclude that provirus insertion exerts a long-range cis effect on the expression of Myc. Therefore, provirus integration in a single locus may affect the expression of multiple genes, some of which may be located a long distance from the site of integration.

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A modified three-stage system was developed for the rapid production of methane from food wastes. The primary stage was a semianaerobic hydrolysis/acidogenic system, in which approx 4100 mg/L of volatile fatty acids (VFAs) was produced at a hydraulic retention time (HRT) of 2 d. The operation temperature and pH were 30 degrees C and 5.0-5.5, respectively. The non-degraded materials were removed through a hole at the bottom of the reactor. The secondary stage was an anaerobic acidogenic system equipped with an upflow anaerobic sludge blanket (UASB) type of fermentor. VFA was accumulated up to 6100 mg/L by the addition of Clostridium butyricum to the reactor at an HRT of 2 d. The optimum temperature and pH range were 35 degrees C and 5.0-5.5, respectively. The tertiary methanogenic stage produced CH4 and CO2 from the VFA in the UASB reactor. Methane content was 72% of the total gas volume, and the yield was 0.45-0.50 m3/kg of volatile solids at an HRT of 12 d. The operation temperature and pH were 41 degrees C and 7.6-7.9, respectively. The three-stage process exhibited an unusually high total chemical oxygen demand reduction rate up to 95%. Total nitrogen decreased to 96% and < 10 mg/L of total phosphorus remained in the final effluent.