A down-regulated epi-allele of the genomes uncoupled 4 gene generates a xantha marker trait in rice.

KEY MESSAGE: A γ-ray-induced xantha trait is epigenetically controlled by the genomes uncoupled 4 gene with enhanced promoter segment methylation and down-regulated expression in rice. For easy testing and to increase varietal purity, a xantha mutation (xnt), which turns plants yellow and makes them visually distinguishable from normal green rice, has been generated and bred into male sterile lines for hybrid rice production. The xnt locus was previously fine mapped to a ~100-kb interval on chromosome 11, but its identity was unknown. In this study, xnt was further narrowed down to a 57-kb fragment carrying eight opening reading frames (ORFs). All eight ORFs had identical genomic sequences and all but ORF2 (g enomes uncoupled 4, OsGUN4) had similar transcript abundance in the xantha mutant Huangyu B (HYB) and its parental variety Longtefu B (LTB). The expression of OsGUN4, however, was significantly reduced in HYB compared with LTB in terms of both transcript abundance (0.2% that of LTB) and expressed protein level (barely detectable in HYB but greater than the heat shock protein reference in LTB). Therefore, OsGUN4 was identified as the candidate gene underlying the xantha trait. The function of OsGUN4 in the xantha phenotype was confirmed by identification and characterization of new allelic OsGUN4 mutations. Comparative bisulfite genomic sequencing of OsGUN4 revealed increased methylation in a promoter region in the mutant, and the correlation between increased methylation and the xantha phenotype was further verified by demethylation treatment. In summary, we have identified an epi-allele of OsGUN4 as the causal gene of the xantha marker trait and revealed that enhanced methylation in its promoter down-regulated its expression in rice.

The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults.

A growing number of empirical studies have revealed that diaphragmatic breathing may trigger body relaxation responses and benefit both physical and mental health. However, the specific benefits of diaphragmatic breathing on mental health remain largely unknown. The present study aimed to investigate the effect of diaphragmatic breathing on cognition, affect, and cortisol responses to stress. Forty participants were randomly assigned to either a breathing intervention group (BIG) or a control group (CG). The BIG received intensive training for 20 sessions, implemented over 8 weeks, employing a real-time feedback device, and an average respiratory rate of 4 breaths/min, while the CG did not receive this treatment. All participants completed pre- and post-tests of sustained attention and affect. Additionally, pre-test and post-test salivary cortisol concentrations were determined in both groups. The findings suggested that the BIG showed a significant decrease in negative affect after intervention, compared to baseline. In the diaphragmatic breathing condition, there was a significant interaction effect of group by time on sustained attention, whereby the BIG showed significantly increased sustained attention after training, compared to baseline. There was a significant interaction effect of group and time in the diaphragmatic breathing condition on cortisol levels, whereby the BIG had a significantly lower cortisol level after training, while the CG showed no significant change in cortisol levels. In conclusion, diaphragmatic breathing could improve sustained attention, affect, and cortisol levels. This study provided evidence demonstrating the effect of diaphragmatic breathing, a mind-body practice, on mental function, from a health psychology approach, which has important implications for health promotion in healthy individuals.

Tai Chi Chuan modulates heart rate variability during abdominal breathing in elderly adults.

Tai Chi Chuan (TCC) practice is currently intentionally applied in clinical populations, especially those with cardiovascular diseases because of its potential benefits on the autonomic nervous system. The long-term effect of TCC practice on heart rate variability (HRV) remains largely unknown. In this study, we recruited 23 TCC practitioners whose experience averaged approximately 21 years and 19 controls matched by age, sex and education to examine the effect of TCC practice on the autonomic nervous system during a resting state and during an abdominal breathing state. HRV was measured by traditional electrocardiogram (ECG) recording. The results showed that the low frequency, total power frequency, and normalized low frequency components and the low-frequency/high-frequency ratio were significantly higher, whereas the normalized high frequency was significantly lower in the TCC practitioners relative to controls during the abdominal breathing state. However, we did not detect any significant difference in the HRV measures during the resting state between the two groups. Additionally, TCC experience did not correlate with HRV components either in the abdominal state or the resting state in the TCC group. Considering all of these findings, we suggest that TCC improves vagal activity and the balance between sympathetic and parasympathetic activity during the relaxation state. This study also provides direct physiological evidence for the role of TCC practice in relaxation.