Substrate DNA Promoting Binding of Mycobacterium tuberculosis MtrA by Facilitating Dimerization and Interpretation of Affinity by Minor Groove Width.

In order to deepen the understanding of the role and regulation mechanisms of prokaryotic global transcription regulators in complex processes, including virulence, the associations between the affinity and binding sequences of Mycobacterium tuberculosis MtrA have been explored extensively. Analysis of MtrA 294 diversified 26 bp binding sequences revealed that the sequence similarity of fragments was not simply associated with affinity. The unique variation patterns of GC content and periodical and sequential fluctuation of affinity contribution curves were observed along the sequence in this study. Furthermore, docking analysis demonstrated that the structure of the dimer MtrA-DNA (high affinity) was generally consistent with other OmpR family members, while Arg 219 and Gly 220 of the wing domain interacted with the minor groove. The results of the binding box replacement experiment proved that box 2 was essential for binding, which implied the differential roles of the two boxes in the binding process. Furthermore, the results of the substitution of the nucleotide at the 20th and/or 21st positions indicated that the affinity was negatively associated with the value of minor groove width precisely at the 21st position. The dimerization of the unphosphorylated MtrA facilitated by a low-affinity DNA fragment was observed for the first time. However, the proportion of the dimer was associated with the affinity of substrate DNA, which further suggested that the affinity was actually one characteristic of the stability of dimers. Based on the finding of 17 inter-molecule hydrogen bonds identified in the interface of the MtrA dimer, including 8 symmetric complementary ones in the conserved α4-ß5-α5 face, we propose that hydrogen bonds should be considered just as important as salt bridges and the hydrophobic patch in the dimerization. Our comprehensive study on a large number of binding fragments with quantitative affinity values provided new insight into the molecular mechanism of dimerization, binding specificity and affinity determination of MtrA and clues for solving the puzzle of how global transcription factors regulate a large quantity of target genes.

Analysis of spatiotemporal mobility of shared-bike usage during COVID-19 pandemic in Beijing.

The entire world is experiencing a crisis in public health and the economy owing to the coronavirus disease 2019 (COVID-19) pandemic. Understanding human mobility during the pandemic helps to formulate interventional strategies and resilient measures. The widely used bike-sharing system (BSS) could illustrate the activities of urban dwellers over time and space in big cities; however, it is rarely reported in epidemiological research. In this article, we analyze the BSS data to examine the human mobility of shared-bike users, detecting the key time nodes of different pandemic stages and demonstrating the evolution of human mobility owing to the onset of the COVID-19 threat and administrative restrictions. We assessed the net impact of the pandemic using the results of co-location analysis between shared-bike usage and points of interest. Our results demonstrate that the pandemic has reduced overall bike usage by 64.8%; however, a subsequent average increase (15.9%) in shared-bike usage has been observed, suggesting partial recovery of productive and residential activities, although far from normal times. These findings could be a reference for epidemiological research, and thereby aid policymaking in the context of the current COVID-19 outbreak and other epidemic events at the city scale.

Differential effects of two types of environmental novelty on activity and sleep in BALB/cJ and C57BL/6J mice.

Change in the sleeping environment can produce significant alterations in sleep. To determine how these alterations may vary with the amount of change and the relative reactivity of the sleeper, we examined the influences of environmental novelty on sleep in two mouse strains that differ in behavioral anxiety. Mice [BALB/cJ (n=7) and C57BL/6J (n=8)] were implanted for recording EEG and activity via telemetry. Following baseline data collection, activity and sleep were examined over 46 h after routine cage change, after placing a simple novel object (PVC Tee) in the home cage, and after handling controls. Mice of both strains showed immediate increases in activity and decreases in rapid eye movement sleep (REM) and non-REM (NREM) after cage change and novel object. Within strain, changes in activity and sleep were greater after cage change than after novel object. Changes in activity and sleep time were significantly correlated in each strain. Compared to C57BL/6J mice, BALB/cJ mice exhibited greater and longer duration initial reductions in sleep time, and greater increases in EEG slow wave activity power after cage change and novel object, but these changes were not followed with subsequent increases in sleep time. In contrast, C57BL/6J mice showed significantly greater subsequent increases in sleep time following the initial reductions induced by both manipulations. The results suggest that initial decreases and subsequent increases in sleep time are related to putative differences in the intensity of environmental novelty (cage change>novel object) and to previously described strain differences in anxiety (BALB/cJ>C57BL/6J).

Strain differences in the influence of open field exposure on sleep in mice.

The open field (OF) is thought to induce anxiety in rodents. It also allows an opportunity for exploration in a novel environment. Less activity in the OF is thought to indicate greater anxiety whereas more activity may reflect greater exploration, and possibly greater exploratory learning. Anxiety and learning have poorly understood relationships to sleep. In order to determine how anxiety and exploration in the OF could influence sleep, we recorded sleep in mouse strains (C57BL/6J (B6), BALB/cJ (C), DBA/2J (D2), and CB6F1/J (CB6)) with different levels of anxiety and exploration after 30 min in an OF. In all strains, OF exposure induced immediate decreases in rapid eye movement sleep (REM) followed by longer latency increases in REM. The time course and amount of REM decreases and increases varied among strains. Compared to less anxious B6, D2 and CB6 mice, C mice had greater and longer lasting immediate decreases in REM. C mice also displayed longer periods of decreases REM and a smaller, longer latency increase in REM. OF exploratory activity was positively correlated to percentage of REM increases from 6 to 10h after OF exposure. The results suggest that the anxiogenic component of the OF produced an immediate decrease in REM that was greater in more "anxious" mice. In contrast, exploration in the OF was associated with increased REM, with the increase greater in less anxious mice. The results are discussed with respect to the potential influences of anxiety and learning on sleep.

Menopausal depression: comparison of hormone replacement therapy and hormone replacement therapy plus fluoxetine.

BACKGROUND: To compare the efficacy and safety of hormone replacement therapy (HRT) combined with fluoxetine, with HRT alone, in post-menopausal women suffering from depression. METHODS: A randomized, open-label, parallel trial was applied. HRT was administered to all patients for 2 cycles, with 14 days of estrogen therapy and 14 days of estrogen plus progesterone. Patients who were randomly assigned to the HRT plus fluoxetine group were given fluoxetine in combination with HRT. Hamilton Depression Rating Scale (HAMD), Kupperman Menopausal Index (KMI), and Clinical Global Impressions scale were used to measure the efficacy. RESULTS: One hundred and twenty-three post-menopausal patients with depression were enrolled in the study. Among them, 120 had at least one post-treatment visit and entered into the statistical analysis. The mean total HAMD scores were significantly lower, and the percentages of HAMD score reductions were higher in the HRT plus fluoxetine Group compared with the HRT Group, after at least 3 weeks of treatment, with an average difference of 5 points at the endpoint. The Clinical Global Impression-Severity and Clinical Global Impression-Improvement scores were significantly different in the 2 groups, in favor of the combination therapy. The mean total KMI was significantly lower in the Combination Group compared with the HRT Group, after at least 6 weeks of treatment, with an average 4.5-point difference between the groups. No statistically significant differences were found in most of the adverse events reported in the Combination Group compared with the HRT group, with the exception of 3 symptoms, i.e., dry mouth, loss of appetite, and abdominal distention. They were mild to moderate in severity. Two patients in the HRT group, but none in the combination group, dropped out due to adverse events. CONCLUSION: HRT plus fluoxetine therapy was effective in the treatment of menopausal depression with a satisfactory safety profile.

GABAergic regulation of REM sleep in reticularis pontis oralis and caudalis in rats.

The nucleus reticularis pontis oralis (RPO) and nucleus reticularis pontis caudalis (RPC) are implicated in the generation of rapid eye movement sleep (REM). Work in cats has indicated that GABA in RPO plays a role in the regulation of REM. We assessed REM after local microinjections into RPO and RPC of the gamma-aminobutyric acid-A (GABA(A)) agonist, muscimol (MUS), and the GABA(A) antagonist, bicuculline (BIC). Rats (90-day-old male Sprague-Dawley) were implanted with electrodes for recording electroencephalographs (EEG) and electromyographs (EMG). Guide cannulae were aimed into RPO (n = 9) and RPC (n = 8) for microinjecting MUS (200, 1,000.0 microM) and BIC (0.056, 0.333, 1.0, 1,000.0, and 10,000.0 microM). Animals received bilateral microinjections of saline, MUS, and BIC (0.2 microl microinjected at 0.1 microl/min) into each region followed by 6-h sleep recordings. In RPO, MUS (1,000.0 microM) suppressed REM and BIC (1,000.0 microM) enhanced REM. In RPC, MUS (200, 1,000.0 microM) suppressed REM, but BIC (1,000.0 microM and less) did not significantly affect REM. Higher concentrations of BIC (10,000.0 microM) injected into RPO (n = 9) and RPC (n = 4) produced wakefulness and escape behavior. The results indicate that GABA in RPO/RPC is involved in the regulation of REM and suggest site-specific differences in this regulation.