Interspecific divergence of circadian properties in duckweed plants

The circadian clock system is widely conserved in plants; however, divergence in circadian rhythm properties is poorly understood. We conducted a comparative analysis of the circadian properties of closely related duckweed species. Using a particle bombardment method, a circadian bioluminescent reporter was introduced into duckweed plants. We measured bioluminescence circadian rhythms of eight species of the genus Lemna and seven species of the genus Wolffiella at various temperatures (20, 25, and 30 °C) and light conditions (constant light or constant dark). Wolffiella species inhabit relatively warm areas and lack some tissues/organs found in Lemna species. Lemna species tended to show robust bioluminescence circadian rhythms under all conditions, while Wolffiella species showed lower rhythm stability, especially at higher temperatures. For Lemna, two species (L. valdiviana and L. minuta) forming a clade showed relatively lower circadian stability. For Wolffiella, two species (W. hyalina and W. repanda) forming a clade showed extremely long period lengths. The circadian properties of species primarily reflect their phylogenetic positions. The relationships between geographical and morphological factors and circadian properties are also suggested.

Uncovering complexity details in actigraphy patterns to differentiate the depressed from the non-depressed

While the negative association between physical activity and depression has been well established, it is unclear what precise characteristics of physical activity patterns explain this association. Complexity measures may identify previously unexplored aspects of objectively measured activity patterns, such as the extent to which individuals show repetitive periods of physical activity and the diversity in durations of such repetitive activity patterns. We compared the complexity levels of actigraphy data gathered over 4 weeks ($$\sim 40000$$ ∼ 40000 data points each) for every individual, from non-depressed ($$n=25$$ n = 25 ) and depressed ($$n=21$$ n = 21 ) groups using recurrence plots. Significantly lower levels of complexity were detected in the actigraphy data from the depressed group as compared to non-depressed controls, both in terms of lower mean durations of periods of recurrent physical activity and less diversity in the duration of these periods. Further, diagnosis of depression was not significantly associated with mean activity levels or measures of circadian rhythm stability, and predicted depression status better than these.

Rest-activity rhythms and white matter microstructure across the lifespan

Study Objectives The purpose of this study was to examine how rest-activity (RA) rhythm stability may be associated with white matter microstructure across the lifespan in healthy adults free of significant cardiovascular risk. Methods We analyzed multi-shell diffusion tensor images from 103 healthy young and older adults using tract-based spatial statistics (TBSS) to examine relationships between white matter microstructure and RA rhythm stability. RA measures were computed using both cosinor and non-parametric methods derived from 7 days of actigraphy data. Fractional anisotropy (FA) and mean diffusivity (MD) were examined in this analysis. Because prior studies have suggested that the corpus callosum (CC) is sensitive to sleep physiology and RA rhythms, we also conducted a focused region of interest analysis on the CC. Results Greater rest-activity rhythm stability was associated with greater FA across both young and older adults, primarily in the CC and anterior corona radiata. This effect was not moderated by age group. While RA measures were associated with sleep metrics, RA rhythm measures uniquely accounted for the variance in white matter integrity. Conclusions This study strengthens existing evidence for a relationship between brain white matter structure and RA rhythm stability in the absence of health risk factors. While there are differences in RA stability between age groups, the relationship with brain white matter was present across both young and older adults. RA rhythms may be a useful biomarker of brain health across both periods of adult development.

Vorhofflimmern: Wie wichtig ist der Erhalt des Sinusrhythmus?

Rhythm control therapy, comprising antiarrhythmic drugs, cardioversion, and AF ablation, is an important component in the management of patients with atrial fibrillation (AF). Catheter ablation for AF, mainly targeting isolation of the pulmonary veins (AF ablation), has markedly improved the effectiveness of rhythm control therapy. Rhythm control improves symptoms and quality of life in patients with symptomatic AF. AF ablation maintains sinus rhythm more effectively than antiarrhythmic drug therapy. Antiarrhythmic drugs remain effective after AF ablation, underpinning the synergistic mechanisms of action of AF ablation and antiarrhythmic drugs. Different lifestyle interventions might additionally improve symptoms and rhythm stability in patients with AF. AF ablation appears to improve left ventricular function in a subset of patients. Summarized, rhythm control therapy in patients with symptomatic AF is safe and improves quality of life, including elderly patients with stroke risk factors. Further studies are needed to determine whether rhythm control therapy reduces AF-related complications while improving patient outcome with regard to prognosis.

Weight loss in conservative treatment of obesity in women is associated with physical activity and circadian phenotype: a longitudinal observational study

Introduction The study investigates the association between circadian phenotype (CP), its stability (interdaily stability - IS) and physical activity (PA) in a weight loss (WL) programme. Methods Seventy-five women in WL conservative treatment (BMI ≥ 25 kg/m2) were measured (for about 3 months in between 2016 and 2018) by actigraphy. Results We observed a difference in time of acrophase (p = 0.049), but no difference in IS (p = 0.533) between women who lost and did not lose weight. There was a difference in PA (mesor) between groups of women who lost weight compared to those who gained weight (p = 0.007). There was a relationship between IS and PA parametres mesor: p0.001; and the most active 10 h of a day (M10): p < 0.001 - the more stable were women in their rhythm, the more PA they have. Besides confirming a relationship between PA and WL, we also found a relation between WL and CP based on acrophase. Although no direct relationship was found for the indicators of rhythm stability (IS), they can be considered very important variables because of their close connection to PA – a main factor that contributes to the success of the WL programme. Discussion According to the results of the study, screening of the CP and its stability may be beneficial in the creation of an individualized WL plan.

Dopaminergic modulation of locomotor network activity in the neonatal mouse spinal cord

Dopamine is now well established as a modulator of locomotor rhythms in a variety of developing and adult vertebrates. However, in mice, while all five dopamine receptor subtypes are present in the spinal cord, it is unclear which receptor subtypes modulate the rhythm. Dopamine receptors can be grouped into two families—the D1/5 receptor group and the D2/3/4 group, which have excitatory and inhibitory effects, respectively. Our data suggest that dopamine exerts contrasting dose-dependent modulatory effects via the two receptor families. Our data show that administration of dopamine at concentrations >35 μM slowed and increased the regularity of a locomotor rhythm evoked by bath application of 5-hydroxytryptamine (5-HT) and N-methyl-d(l)-aspartic acid (NMA). This effect was independent of the baseline frequency of the rhythm that was manipulated by altering the NMA concentration. We next examined the contribution of the D1- and D2-like receptor families on the rhythm. Our data suggest that the D1-like receptor contributes to enhancement of the stability of the rhythm. Overall, the D2-like family had a pronounced slowing effect on the rhythm; however, quinpirole, the D2-like agonist, also enhanced rhythm stability. These data indicate a receptor-dependent delegation of the modulatory effects of dopamine on the spinal locomotor pattern generator.