Inhibitor of DNA binding 2 (ID2) is a helix-loop-helix transcriptional repressor rhythmically expressed in many adult tissues. Our earlier studies have demonstrated a role for ID2 in the input pathway, core clock function and output pathways of the mouse circadian system. We have also reported that Id2 null (Id2−/−) mice are lean with low gonadal white adipose tissue deposits and lower lipid content in the liver. These results coincided with altered or disrupted circadian expression profiles of liver genes including those involved in lipid metabolism. In the present phenotypic study we intended to decipher, on a sex-specific basis, the role of ID2 in glucose metabolism and in the circadian regulation of activity, important components of energy balance. We find that Id2−/− mice exhibited altered daily and circadian rhythms of feeding and locomotor activity; activity profiles extended further into the late night/dark phase of the 24-hr cycle, despite mice showing reduced total locomotor activity. Also, male Id2−/− mice consumed a greater amount of food relative to body mass, and displayed less weight gain. Id2−/− females had smaller adipocytes, suggesting sexual-dimorphic programing of adipogenesis. We observed increased glucose tolerance and insulin sensitivity in male Id2−/− mice, which was exacerbated in older animals. FDG-PET analysis revealed increased glucose uptake by skeletal muscle and brown adipose tissue of male Id2−/− mice, suggesting increased glucose metabolism and thermogenesis in these tissues. Reductions in intramuscular triacylglycerol and diacylglycerol were detected in male Id2−/− mice, highlighting its possible mechanistic role in enhanced insulin sensitivity in these mice. Our findings indicate a role for ID2 as a regulator of glucose and lipid metabolism, and in the circadian control of feeding/locomotor behavior; and contribute to the understanding of the development of obesity and diabetes, particularly in shift work personnel among whom incidence of such metabolic disorders is elevated.

This review analyses the role of viologens, a unique class of redox-active molecules in various energy storage devices and the nature of chemical interactions in enhancing their overall performances.

A fully automated procedure for detecting and centering protein crystals in the X-ray beam of a macromolecular crystallography beamline has been developed. A cryo-loop centering routine that analyzes video images with an edge detection algorithm is first used to determine the dimensions of the loop holding the sample; then low-dose X-rays are used to record diffraction images in a grid over the edge and face plane of the loop. A three-dimensional profile of the crystal based on the number of diffraction spots in each image is constructed. The derived center of mass is then used to align the crystal to the X-ray beam. Typical samples can be accurately aligned in approximately 2-3 min. Because the procedure is based on the number of ;good' spots as determined by the program Spotfinder, the best diffracting part of the crystal is aligned to the X-ray beam.