Type II Protein Arginine Methyltransferase 5 (PRMT5) Is Required for Circadian Pperiod Determination in Arabidopsis Thaliana

Posttranslational modification is an important element in circadian clock function from cyanobacteria through plants and mammals. For example, a number of key clock components are phosphorylated and thereby marked for subsequent ubiquitination and degradation. Through forward genetic analysis we demonstrate that protein arginine methyltransferase 5 (PRMT5; At4g31120) is a critical determinant of circadian period in Arabidopsis. PRMT5 is coregulated with a set of 1,253 genes that shows alterations in phase of expression in response to entrainment to thermocycles versus photocycles in constant temperature. PRMT5 encodes a type II protein arginine methyltransferase that catalyzes the symmetric dimethylation of arginine residues (Rsme2). Rsme2 modification has been observed in many taxa, and targets include histones, components of the transcription complex, and components of the spliceosome. Neither arginine methylation nor PRMT5 has been implicated previously in circadian clock function, but the period lengthening associated with mutational disruption of prmt5 indicates that Rsme2 is a decoration important for the Arabidopsis clock and possibly for clocks in general

Genetic determinants of in vivo fitness and diet responsiveness in multiple human gut Bacteroides

International audienceno abstrac

A high dairy protein, high-calcium diet minimizes bone turnover in overweight adults during weight loss

Weight loss induces bone resorption and this can be attenuated by calcium supplementation. Protein-rich diets were recently associated with favorable effects on bone density, although this remains controversial. We hypothesized that a diet high in calcium and protein would minimize bone resorption during weight loss compared with a lower calcium, protein-rich diet. The effects of dietary calcium in high protein diets on calcium excretion and bone metabolism were examined in overweight adults (n = 50, BMI 33.4 +/- 2.1 kg/m(2)) during 12 wk of energy restriction followed by 4 wk of energy balance. Subjects were randomly assigned to isoenergetic diets (5.5 MJ/d, 34% energy from protein, 41% carbohydrate, 24% fat) high in either dairy protein (DP, 2400 mg Ca/d) or mixed protein sources (MP, 500 mg Ca/d). During energy restriction, weight loss was 10% (-9.7 +/- 3.8 kg, P < 0.01), and 24-h urinary calcium excretion decreased independently of diet (-1.09 +/- 0.23 mmol/d, P < 0.01). By wk 16, the MP diet group had a 40% greater increase in deoxypyridinoline (bone resorption marker) than the DP diet group (P = 0.008). Osteocalcin (bone formation marker) increased from wk 0 to 16 in only the MP diet group [+2.16 +/- 0.63 micro g/L (+0.63 +/- 0.11nmol/L), P = 0.001]. In conclusion, weight loss was associated with increased bone resorption, yet the DP diet had a modest advantage over the MP diet by minimizing overall turnover. Combined with reduced urinary calcium excretion, this suggests that a high-protein, calcium-replete diet may protect against bone loss during weight reduction.Jane Bowen, Manny Noakes and Peter M. Clifto