RpuS/R Is a Novel Two-Component Signal Transduction System That Regulates the Expression of the Pyruvate Symporter MctP in Sinorhizobium fredii NGR234.

The SLC5/STAC histidine kinases comprise a recently identified family of sensor proteins in two-component signal transduction systems (TCSTS), in which the signaling domain is fused to an SLC5 solute symporter domain through a STAC domain. Only two members of this family have been characterized experimentally, the CrbS/R system that regulates acetate utilization in Vibrio and Pseudomonas, and the CbrA/B system that regulates the utilization of histidine in Pseudomonas and glucose in Azotobacter. In an attempt to expand the characterized members of this family beyond the Gammaproteobacteria, we identified two putative TCSTS in the Alphaproteobacterium Sinorhizobium fredii NGR234 whose sensor histidine kinases belong to the SLC5/STAC family. Using reverse genetics, we were able to identify the first TCSTS as a CrbS/R homolog that is also needed for growth on acetate, while the second TCSTS, RpuS/R, is a novel system required for optimal growth on pyruvate. Using RNAseq and transcriptional fusions, we determined that in S. fredii the RpuS/R system upregulates the expression of an operon coding for the pyruvate symporter MctP when pyruvate is the sole carbon source. In addition, we identified a conserved DNA sequence motif in the putative promoter region of the mctP operon that is essential for the RpuR-mediated transcriptional activation of genes under pyruvate-utilizing conditions. Finally, we show that S. fredii mutants lacking these TCSTS are affected in nodulation, producing fewer nodules than the parent strain and at a slower rate.

Perceived Diet Quality, Eating Behaviour, and Lifestyle Changes in a Mexican Population with Internet Access during Confinement for the COVID-19 Pandemic: ESCAN-COVID19Mx Survey.

Perceived changes in diet quality, emotional eating, physical activity, and lifestyle were evaluated in a group of Mexican adults before and during COVID-19 confinement. In this study, 8289 adults answered an online questionnaire between April and May 2020. Data about sociodemographic characteristics, self-reported weight and height, diet quality, emotional eating, physical activity, and lifestyle changes were collected. Before and after confinement, differences by sociodemographic characteristics were assessed with Wilcoxon, Anova, and linear regression analyses. Most participants were women (80%) between 18 and 38 years old (70%), with a low degree of marginalisation (82.8%) and a high educational level (84.2%); 53.1% had a normal weight and 31.4% were overweight. Half (46.8%) of the participants perceived a change in the quality of their diet. The Diet Quality Index (DQI) was higher during confinement (it improved by 3 points) in all groups, regardless of education level, marginalisation level, or place of residence (p < 0.001). Lifestyle changes were present among some of the participants, 6.1% stopped smoking, 12.1% stopped consuming alcohol, 53.3% sleep later, 9% became more sedentary, and increased their screen (43%) as well as sitting and lying down time (81.6%). Mexicans with Internet access staying at home during COVID-19 confinement perceived positive changes in the quality of their diet, smoking, and alcohol consumption, but negative changes in the level of physical activity and sleep quality. These results emphasise the relevance of encouraging healthy lifestyle behaviours during and after times of crisis to prevent the risk of complications due to infectious and chronic diseases.

Intranasal gene transfer by chitosan-DNA nanospheres protects BALB/c mice against acute respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) infection is often associated in infancy with life-threatening bronchiolitis, which is also a major risk factor for the development of asthma. At present, no effective prophylaxis is available against RSV infection. Herein, we describe an effective prophylactic intranasal gene transfer strategy utilizing chitosan-DNA nanospheres (IGT), containing a cocktail of plasmid DNAs encoding all RSV antigens, except L. A single administration of IGT (25 microg/mouse) induces expression of the mRNA and proteins of all antigens in the lung and results in a significant reduction of viral titers and viral antigen load after acute RSV infection of these mice. IGT-administered mice show no significant change in airway reactivity to methacholine and no apparent pulmonary inflammation. Furthermore, IGT results in significant induction of RSV-specific IgG antibodies, nasal IgA antibodies, cytotoxic T lymphocytes, and interferon-gamma production in the lung and splenocytes compared with controls. Together, these results demonstrate the potential of IGT against acute RSV infection.

In vitro release of vascular endothelial growth factor from gadolinium-doped biodegradable microspheres.

A drug delivery vehicle was constructed that could be visualized noninvasively with MRI. The biodegradable polymer poly(DL-lactic-co-glycolic acid) (PLGA) was used to fabricate microspheres containing vascular endothelial growth factor (VEGF) and the MRI contrast agent gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA). The microspheres were characterized in terms of size, drug and contrast agent encapsulation, and degradation rate. The PLGA microspheres had a mean diameter of 48 +/- 18 microm. The gadolinium loading was 17 +/- 3 microg/mg polymer and the VEGF loading was 163 +/- 22 ng/mg polymer. Electron microscopy revealed that the Gd was dispersed throughout the microspheres and it was confirmed that the Gd loading was sufficient to visualize the microspheres under MRI. VEGF and Gd-DTPA were released from the microspheres in vitro over a period of approximately 6 weeks in three phases: a burst, followed by a slow steady-state, then a rapid steady-state. Biodegradable Gd-doped microspheres can be effectively used to deliver drugs in a sustained manner, while being monitored noninvasively with MRI.