Involvement of ArlI, ArlJ, and CirA in archaeal type IV pilin-mediated motility regulation.

Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established; however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that the deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon Haloferax volcanii non-motile. In this study, we used ethyl methanesulfonate mutagenesis and a motility assay to identify motile suppressors of the ∆pilA[1-6] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, arlI and arlJ. In trans expression of arlI and arlJ mutant constructs in the respective multi-deletion strains ∆pilA[1-6]∆arlI and ∆pilA[1-6]∆arlJ confirmed their role in suppressing the ∆pilA[1-6] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in cirA, a gene encoding a proposed regulatory protein. A deletion of cirA resulted in hypermotility, while cirA expression in trans in wild-type cells led to decreased motility. Moreover, quantitative real-time PCR analysis revealed that in wild-type cells, higher expression levels of arlI, arlJ, and the archaellin gene arlA1 were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ∆cirA cells, which form rods during both early- and mid-log phases, exhibited similar expression levels of arl genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.IMPORTANCEArchaea are close relatives of eukaryotes and play crucial ecological roles. Certain behaviors, such as swimming motility, are thought to be important for archaeal environmental adaptation. Archaella, the archaeal motility appendages, are evolutionarily distinct from bacterial flagella, and the regulatory mechanisms driving archaeal motility are largely unknown. Previous research has linked the loss of type IV pili subunits to archaeal motility suppression. This study reveals three Haloferax volcanii proteins involved in pilin-mediated motility regulation, offering a deeper understanding of motility regulation in this understudied domain while also paving the way for uncovering novel mechanisms that govern archaeal motility. Understanding archaeal cellular processes will help elucidate the ecological roles of archaea as well as the evolution of these processes across domains.

Involvement of ArlI, ArlJ, and CirA in Archaeal Type-IV Pilin-Mediated Motility Regulation.

Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established, however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon Haloferax volcanii non-motile. In this study, we used EMS mutagenesis and a motility assay to identify motile suppressors of the ΔpilA[1-6] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, arlI and arlJ. Overexpression of these arlI and arlJ mutant constructs in the respective multi-deletion strains ΔpilA[1-6]ΔarlI and ΔpilA[1-6]ΔarlJ confirmed their role in suppressing the ΔpilA[1-6] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in cirA, a gene encoding a proposed regulatory protein. A deletion of cirA resulted in hypermotility, while cirA overexpression in wild-type cells led to decreased motility. Moreover, qRT-PCR analysis revealed that in wild-type cells, higher expression levels of arlI, arlJ, and the archaellin gene arlA1 were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ΔcirA cells, which form rods during both early and mid-log phases, exhibited similar expression levels of arl genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.

Alternative approaches to treat bacterial infections: targeting quorum-sensing.

Introduction: The emergence of multi- and pan-drug-resistant bacteria represents a global crisis that calls for the development of alternative anti-infective strategies. These comprise anti-virulence approaches, which target pathogenicity without exerting a bacteriostatic or bactericidal effect and are claimed to reduce the development of resistance. Because in many pathogens, quorum-sensing (QS) systems control the expression of virulence factors, interference with QS, or quorum-quenching, is often proposed as a strategy with a broad anti-virulence effect.Areas covered: We discuss the role and regulatory targets of QS control in selected Gram-positive and Gram-negative bacteria, focusing on those with clinical importance and QS control of virulence. We present the components of QS systems that form possible targets for the development of anti-virulence drugs and discuss recent research on quorum-quenching approaches to control bacterial infection.Expert opinion: While there has been extensive research on QS systems and quorum-quenching approaches, there is a paucity of in-vivo research using adequate animal models to substantiate applicability. In-vivo research on QS blockers needs to be intensified and optimized to use clinically relevant setups, in order to underscore that such drugs can be used effectively to overcome problems associated with the treatment of severe infections by antibiotic-resistant pathogens.

An Ecological Approach to Obesity in Mexican American Children.

INTRODUCTION: The objective of this study was to explore the risk factors that contribute to obesity in Mexican American children compared with Mexican American normal weight children. No hypotheses were tested in the study. When risk factors are known, nurses can use evidence to reduce risky behavior. METHOD: A cross-sectional descriptive design was used, comparing two groups of children to discern the risk factors for obesity. The setting is a county in South Texas along the border with Mexico. The sample consisted of 55 Mexican American dyads (mother-child). The following measures, based on the Ecological Model of Growth, were used to collect data: anthropometrics, dietary data of children, home environment, perceived stress of mother, and maternal acculturation. Independent sample t tests, chi-square tests, Fisher exact tests, and a hierarchical logistic regression analysis were used to analyze the data. RESULTS: The findings show children's age and maternal body mass index (BMI) are positively correlated with childhood obesity, as measured by BMI percentile by age/sex. There were significant differences in the host and agent factors of prolonged bottle feeding, amount of outdoor play, and fruit drinks between normal weight and obese children. DISCUSSION: Engagement and involvement of other family members in outdoor activities, nutrition/feeding, and child care may mitigate the negative effects of host and agent factors on child body size.

Outcomes of Children with Severe Acute Malnutrition in a Tribal Day-care Setting.

OBJECTIVE: To describe the nutritional outcomes of children with severe acute malnutrition (SAM) in a village-level intervention. METHODS: This observational longitudinal study on 179 children aged <3 years was conducted in seven tribal blocks of Central and Eastern India with SAM managed in a comprehensive day care program. RESULTS: 76% children with SAM showed improvement over a 4-6 months period, with 37% shifting to normal anthrometric status. There was a significant shift in Z scores. CONCLUSION: This community-based intervention showed fair results for management of children with SAM at village level.

Allelopathic effect of Ashwagandha against the germination and radicle growth of Cicer arietinum and Triticum aestivum.

BACKGROUND: Ashwagandha (Withania somnifera) is an important medicinal plant in Indian traditional system of medicine and traditionally has been used for several medicinal purposes in the Indian subcontinent. OBJECTIVE: The present study was aimed at the evaluation of allelopathic effect of hydroalcoholic extract of ashwagandha against germination and radicle growth of Cicer arietinum and Triticum aestivum seeds. MATERIALS AND METHODS: The extract at different concentrations was incubated in controlled conditions with the surface sterilized seeds of C. arietinum and T. aestivum and observed periodically for seed germination and radicle growth to assess the allelopathic behavior. RESULTS: The extract mainly at higher concentrations demonstrated promising allelopathic potential by significantly affecting seed germination and radicle elongation of both C. arietinum and T. aestivum in a concentration dependent manner. T. aestivum was found to be more sensitive than C. arietinum. CONCLUSION: The present study demonstrated remarkable allelopathic potential of ashwagandha against the test seeds. The effect was plausibly due to the alkaloid and withanolide contents of ashwagandha.

Evaluation of anti-inflammatory effects of green tea and black tea: A comparative in vitro study.

The present study was conducted to evaluate and compare the anti-inflammatory effects of aqueous extracts of green tea and black tea leaves (Camellia sinensis) against the denaturation of protein in vitro. The test extracts at different concentrations were incubated with egg albumin under controlled experimental conditions and subjected to determination of absorbance to assess the anti-inflammatory property. Diclofenac sodium was used as the reference drug. The present results exhibited a concentration-dependent inhibition of protein (albumin) denaturation by both the tea extracts. From the present findings it can be concluded that both green and black tea leaves possessed a marked anti-inflammatory effect against the denaturation of protein, in vitro. Green tea was found to be more active than black tea, plausibly due to the higher flavonoid contents of green tea.

Neuropharmacological properties of Mikania scandens (L.) Willd. (Asteraceae).

Mikania scandens (L.) Willd. (Asteraceae), known as climbing hemp weed in English, is a herbaceous climbing vine grown as a weed throughout the plains of the Indian subcontinent. The present study evaluated some neuropharmacological properties of hydroalcoholic extract of aerial parts from M. scandens (HAMS) in experimental animal models. HAMS (at 250 and 500 mg/kg body weight, i.p.) was evaluated for central antinociceptive activity by tail flick method. Locomotor depressant activity was measured by means of an actophotometer. Skeletal muscle relaxant effect was evaluated by using rotarod apparatus and sedative potentiating property by phenobarbitone-induced sleep potentiation study. The results of the present study revealed significant (P<0.001) and dose-dependent central antinociceptive, locomotor depressant, muscle relaxant, and sedative potentiating effects of HAMS, demonstrating its depressant action on the central nervous system (CNS). From the present study, it can be concluded that the aerial parts of M. scandens possessed prominent depressant action on the CNS, as manifested by the important neuropharmacological properties in mice.