Structure of a bacterial type IV secretion core complex at subnanometre resolution

Type IV secretion (T4S) systems are able to transport DNAs and/or proteins through the membranes of bacteria. They form large multiprotein complexes consisting of 12 proteins termed VirB1-11 and VirD4. VirB7, 9 and 10 assemble into a 1.07 MegaDalton membrane-spanning core complex (CC), around which all other components assemble. This complex is made of two parts, the O-layer inserted in the outer membrane and the I-layer inserted in the inner membrane. While the structure of the O-layer has been solved by X-ray crystallography, there is no detailed structural information on the I-layer. Using high-resolution cryo-electron microscopy and molecular modelling combined with biochemical approaches, we determined the I-layer structure and located its various components in the electron density. Our results provide new structural insights on the CC, from which the essential features of T4S system mechanisms can be derived

Occupational Health and Safety Trainees Reflect on their Education and Future Careers During COVID-19.

Background: The National Institute for Occupational Safety and Health (NIOSH) funded Education and Research Centers (ERCs), located at 18 universities, with the mission to train occupational safety and health (OSH) leaders. The Florida Sunshine ERC has trained hundreds of students since its inception in 1997 through seven programs that collaboratively foster interdisciplinary education and applied research and practice. The COVID-19 pandemic has presented practical challenges for educators, students, and trainees, forcing institutions to move to remote learning. The pandemic also magnifies the importance of public health and OSH. Purpose: This evaluation elicited feedback from ERC trainees early in the pandemic (2020) and again in 2021 on how the pandemic affected their training, professional development, career plans, and wellbeing. Methods: Open-ended surveys were collected and focus groups were held with currently enrolled trainees from seven Sunshine ERC programs. Descriptive statistics were calculated, and qualitative transcripts were analyzed using MAXQDA software. Results: Through survey responses (45 respondents) and focus group discussions (9 participants), ERC trainees shared their perspectives on pandemic impacts in their performance and wellbeing, transition to remote learning, their respective OSH fields, and career plans during the pandemic. Programs should consider enhancing OSH curricula to respond to training needs and issues related to occupational stress and well-being, pragmatism and disaster response, and even more interdisciplinary training to prepare for emerging population-wide threats. Conclusions: OSH training will require shifts in teaching modalities and content to prepare OSH professionals for the future. Evaluation results informed teaching and training modifications to ensure that ERC objectives continue to be met and that trainees are well-prepared and supported

An Analysis of Maternal, Social and Household Factors Associated with Childhood Anemia

Anemia is highly prevalent in all strata of populations in India, with established evidence of intergenerational anemia. The state of Madhya Pradesh was selected to study childhood anemia as the population is mostly rural, with many tribal districts, and has the highest infant mortality rate in India. This study aims to understand the maternal, social and household factors that affect anemia among children aged 6 months to 5 years by analyzing the the National Family Health Survey (NFHS) conducted in 2015–2016. Children aged 6–59 months with estimated hemoglobin levels were included in this study. Bivariate and multivariable analyses were conducted to understand associations between childhood anemia and various socioeconomic factors. Two models to understand the presence of anemia and the levels of anemia were computed. Higher likelihood of having severe childhood anemia was observed among children of younger mothers (15- to 19-year-old mothers (adjusted odds ratio (aOR) 2.08, 95% confidence interval (CI): 1.06, 4.06, less educated (uneducated mothers aOR 2.25, 95% CI 1.13, 4.48) and belonged to a scheduled tribe (aOR 1.88, 95% CI 1.07, 3.29). Strong associations between anemia in mothers and their children suggest intergenerational anemia which has long-term effects. Malnourished children (severe stunting aOR 3.19, 95% CI 2.36, 4.31) and children born with very low birth weight (aOR 4.28, 95% CI 2.67, 6.87) were more likely to have anemia. These findings strongly suggest more proactive interventions including prenatal healthcare for women and monitoring of the nutrition children at the community level to combat childhood anemia. Evaluations of existing programs should be conducted to understand the gaps in reducing anemia and malnutrition in children

Numerical Study on the Influence of Mass and Stiffness Ratios on the Vortex Induced Motion of an Elastically Mounted Cylinder for Harnessing Power

Harnessing the power of vortices shed in the wake of bluff bodies is indeed a boon to society in the face of fuel crisis. This fact serves as an impetus to develop a device called a hydro vortex power generator (HVPG), comprised of an elastically mounted cylinder that is free to oscillate in the cross-flow (CF) direction even in a low velocity flow field. The oscillatory motions in turn can be converted to useful power. This paper addresses the influence of system characteristics viz. stiffness ratio (k*) and mass ratio (m*) on the maximum response amplitude of the elastically mounted cylinder. Computational fluid dynamics (CFD) simulations have been used here to solve a two way fluid–structure interaction (FSI) problem for predicting the trend of variation of the non-dimensional amplitude Y/D with reduced velocity Ur through a series of simulations. Maximum amplitude motions have been attributed to the lowest value of m* with Ur = 8. However, the maximum lift forces correspond to Ur = 4, providing strong design inputs as well as indicating the best operating conditions. The numerical results have been compared with those of field tests in an irrigation canal and have shown reasonable agreement

Protein oligomerization in the bacterial outer membrane (Review)

The formation of homo-oligomeric assemblies is a well-established characteristic of many soluble proteins and enzymes. Oligomerization has been shown to increase protein stability, allow allosteric cooperativity, shape reaction compartments and provide multivalent interaction sites in soluble proteins. In comparison, our understanding of the prevalence and reasons behind protein oligomerization in membrane proteins is relatively sparse. Recent progress in structural biology of bacterial outer membrane proteins has suggested that oligomerization may be as common and versatile as in soluble proteins. Here we review the current understanding of oligomerization in the bacterial outer membrane from a structural and functional point of vie

Mechanical and tribological performance of Al-Fe-SiC-Zr hybrid composites produced through powder metallurgy process

In this work a ternary Al-Fe-SiC metal matrix composites were reinforced using Zr particles through powder metallurgy process. The Al matrix and the reinforcements were mixed in high energy ball mill at a speed of 250 rpm over a period of 5 h so as to develop a homogenously dispersed composite material. The composite powders are then pressed at 500 MPa using hydraulic press. The compressed composite green compacts are then sintered at 500 °C for 2 h and allowed to cool under furnace atmosphere. The densities, micro hardness and compressive strength of Al-Fe-SiC-Zr composites were investigated and reported. The composite materials were characterized using SEM, EDS and XRD. The density of Al-10Fe-10SiC-10Zr hybrid composites was found to be around 3.44 g cm ^−3 . The Zr particles have influenced the micro hardness of the composite materials. The micro hardness of the Al-10Fe-10SiC-10Zr hybrid composites was found to be better compared to Al-10Fe and Al-10Fe-10SiC hybrid composites. The compressive strength of the Al-10Fe-10SiC-10Zr hybrid composites was around 205 MPa which is 44% higher than the Al-10Fe composite material. The porosity of the hybrid composites has reduced when compared to that of Al-10Fe and Al-10Fe-10SiC hybrid composites. The wear studies reveal that Al-10Fe-10SiC-10Zr bear out better wear resistance. The predominant wear mechanism was identified as adhesive wear followed by plastic deformation. This improved wear resistance was due to the formation of oxides layers such Al _2 O _3 , Fe _2 O _3 and also due to the presence of AlFe _3 and Al _3 Zr _4 intermetallics

The RNA degradosome: life in the fast lane of adaptive molecular evolution

In Escherichia coli, the multi-enzyme RNA degradosome contributes to the global, posttranscriptional regulation of gene expression. The degradosome components are recognized through natively unstructured "microdomains" comprising as few as 15-40 amino acids. Consequently, the degradosome might experience a comparatively smaller number of evolutionary constraints, because there is little requirement to maintain a folded state for the interaction sites. New regulatory properties of the degradosome could arise with relative rapidity, because partners that modify its function could be recruited by quickly evolving microdomains. The unusual combination of the centrality of RNA degradation in gene expression and the generality of natively unstructured microdomains in recognition can fortuitously confer a capacity for efficacious adaptive change to degradosome-like assemblies in eubacteria

Structural biology of bacterial secretion systems in gram-negative pathogens--potential for new drug targets

Gram-negative bacteria have evolved diverse secretion systems/machineries to translocate substrates across the cell envelope. These various machineries fulfil a wide variety of functions but are also essential for pathogenic bacteria to infect human or plant cells. Secretion systems, of which there are seven, utilize one of two secretion mechanisms: (i) the one-step mechanism, whereby substrates are translocated directly from the bacterial-cytoplasm to the extracellular medium or into the eukaryotic-target cell; (ii) the two-step mechanism, whereby substrates are first translocated across the bacterial-inner membrane; once in the periplasm, substrates are targeted to one of the secretion systems that mediate the transport across the outer membrane and the release outside the bacterial cell. This review describes in details the main structural features of these secretion systems. Structural biology offers the possibility to understand the molecular mechanisms at play in the various secretion systems. It also helps to design specifically drugs that can block these machineries and thus attenuate the virulence of pathogenic bacteria

Application of wavelet techniques for cancer diagnosis using ultrasound images: A Review

Ultrasound is an important and low cost imaging modality used to study the internal organs of human body and blood flow through blood vessels. It uses high frequency sound waves to acquire images of internal organs. It is used to screen normal, benign and malignant tissues of various organs. Healthy and malignant tissues generate different echoes for ultrasound. Hence, it provides useful information about the potential tumor tissues that can be analyzed for diagnostic purposes before therapeutic procedures. Ultrasound images are affected with speckle noise due to an air gap between the transducer probe and the body. The challenge is to design and develop robust image preprocessing, segmentation and feature extraction algorithms to locate the tumor region and to extract subtle information from isolated tumor region for diagnosis. This information can be revealed using a scale space technique such as the Discrete Wavelet Transform (DWT). It decomposes an image into images at different scales using low pass and high pass filters. These filters help to identify the detail or sudden changes in intensity in the image. These changes are reflected in the wavelet coefficients. Various texture, statistical and image based features can be extracted from these coefficients. The extracted features are subjected to statistical analysis to identify the significant features to discriminate normal and malignant ultrasound images using supervised classifiers. This paper presents a review of wavelet techniques used for preprocessing, segmentation and feature extraction of breast, thyroid, ovarian and prostate cancer using ultrasound image

Statewide Implementation of Virtual Perinatal Home Visiting During COVID-19

Purpose: This evaluation describes efforts taken by MIECHV administrators and staff during the pandemic using data collected from 60 MIECHV staff surveys and nine statewide weekly focus groups. Description: The Florida Maternal, Infant and Early Childhood Home Visiting (MIECHV) Initiative funds perinatal home visiting for pregnant women and families with infants throughout the state. Florida MIECHV has shown resilience to disasters and times of crises in the past, while generating a culture of adaptation and continuous quality improvement among local implementing agencies. Florida MIECHV responded to the COVID-19 pandemic crisis within the first few days of the first reported case in Florida by providing guidance on virtual home visits and working remotely. Assessment: Findings highlight the role of administrative leadership and communication, staff willingness/morale, logistical considerations, and the needs of enrolled families who face hardships during the pandemic such as job loss, limited supplies, food insecurity, technology limitations, and stress. Home visitors support enrolled families by connecting them with resources, providing public health education and delivering evidence-based home visiting curricula virtually. They also recognized the emotional burden surrounding COVID-19 impacts and uncertainties along with achieving work-life balance by caring for their own children. Conclusion: This evaluation helped in understanding the impact of the pandemic on this maternal and child health program and fundamentals of transition to virtual home visiting services. Virtual home visiting appears to be feasible and provides an essential connection to supports for families who may not otherwise have the means or knowledge to access them