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At least 19 records

All sources NASA NTRS DOE OSTI

NASA NTRS2021

Kinetically Tunable, Active Auxetic, and Variable Recruitment Active Textiles from Hierarchical Assemblies

Multifunctional textiles with programmable, multi-axial, distributed, and scalable actuation are highly desirable and presently unrealized. 1D torque-unbalanced active yarns within 2D textile structures are exploited to produce soft and scalable active textiles that exhibit tunable displacements, forces, stiffnesses, and kinematic deformations. Through a textile hierarchy spanning active material composition, yarn construction, textile geometry, and system architecture, these active textiles accomplish kinetic tunability, variable recruitment behaviors, and auxetic effects without mechanical contact, called active auxetic effects. New modes of pre-programmed multi-axial performance are enabled by geometrically manipulating—specifically pre-stressing and constraining—active filaments in torsion and leveraging their structural elastic instability within a textile geometry. The new kinematic motion afforded by torque-unbalanced active yarns enhances the performance of active textiles, which accomplish tensile strokes over 40%, generated blocked forces up to 308 N m−1, and specific work over 0.4. kJ kg−1. Advances in active textiles are demonstrated through multifunctional 3D applications, including a variable constriction pump that exhibits sequential actuation, a wearable that conforms multi-axially around the body, and a soft exoskeleton that performs assistive motions and on-body anchoring simultaneously. By harnessing the capabilities of active materials within a textile hierarchy, advances in the potentiality of multifunctional textiles are presented.

Active auxetic effects↗

NASA NTRS2001

Role of motor unit structure in defining function

Motor units, defined as a motoneuron and all of its associated muscle fibers, are the basic functional units of skeletal muscle. Their activity represents the final output of the central nervous system, and their role in motor control has been widely studied. However, there has been relatively little work focused on the mechanical significance of recruiting variable numbers of motor units during different motor tasks. This review focuses on factors ranging from molecular to macroanatomical components that influence the mechanical output of a motor unit in the context of the whole muscle. These factors range from the mechanical properties of different muscle fiber types to the unique morphology of the muscle fibers constituting a motor unit of a given type and to the arrangement of those motor unit fibers in three dimensions within the muscle. We suggest that as a result of the integration of multiple levels of structural and physiological levels of organization, unique mechanical properties of motor units are likely to emerge. Copyright 2001 John Wiley & Sons, Inc.

Non-NASA Center↗

NASA NTRS2001

Fiber-type susceptibility to eccentric contraction-induced damage of hindlimb-unloaded rat AL muscles

Slow oxidative (SO) fibers of the adductor longus (AL) were predominantly damaged during voluntary reloading of hindlimb unloaded (HU) rats and appeared explainable by preferential SO fiber recruitment. The present study assessed damage after eliminating the variable of voluntary recruitment by tetanically activating all fibers in situ through the motor nerve while applying eccentric (lengthening) or isometric contractions. Muscles were aldehyde fixed and resin embedded, and semithin sections were cut. Sarcomere lesions were quantified in toluidine blue-stained sections. Fibers were typed in serial sections immunostained with antifast myosin and antitotal myosin (which highlights slow fibers). Both isometric and eccentric paradigms caused fatigue. Lesions occurred only in eccentrically contracted control and HU muscles. Fatigue did not cause lesions. HU increased damage because lesioned- fiber percentages within fiber types and lesion sizes were greater than control. Fast oxidative glycolytic (FOG) fibers were predominantly damaged. In no case did damaged SO fibers predominate. Thus, when FOG, SO, and hybrid fibers are actively lengthened in chronically unloaded muscle, FOG fibers are intrinsically more susceptible to damage than SO fibers. Damaged hybrid-fiber proportions ranged between these extremes.

Non-NASA Center↗

DOE OSTI2025

Signatures of local nitrogen adaptation in the Brachypodium distachyon root microbiome

Plants associate with diverse microbiomes that impact their fitness, yet the contribution of the microbiome to plant adaptation is uncertain. As plant recruitment of its microbiome can be both highly variable and genetically determined, we hypothesized this recruitment process may be the result of adaptive evolution, and contributing to plant local adaptation. We investigated the evolution and adaptive benefit of plant–microbiome recruitment by characterizing the rhizosphere communities across a genotypic panel of Brachypodium distachyon in a common garden experiment. By linking microbial communities to their host genotype's historic environment, we identified signatures of selection on plant–microbiome recruitment. Plant–microbiome composition was significantly correlated with the host genotype's historic environment, with enrichment of microbial traits aligned to local resource conditions. For example, genotypes from low-nitrogen environments recruited communities enriched in nitrogen acquisition traits. In a complementary experiment evaluating plant nitrogen response, these same genotypes were well-adapted to low-nitrogen environments, contingent on the presence of key nitrogen-cycling microbes. These results suggest that local adaptation in plants may partially be mediated by recruitment of beneficial microbiomes. This perspective suggests that plant adaptation may be an emergent property of host–microbe interactions, where evolutionary responses favor traits that promote recruitment of locally beneficial microbiomes.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Simulating environmentally-sensitive tree recruitment in vegetation demographic models

Vegetation demographic models (VDMs) endeavor to predict how global forests will respond to climate change. This requires simulating which trees, if any, are able to recruit under changing environmental conditions. We present a new recruitment scheme for VDMs in which functional-type-specific recruitment rates are sensitive to light, soil moisture and the productivity of reproductive trees. We evaluate the scheme by predicting tree recruitment for four tropical tree functional types under varying meteorology and canopy structure at Barro Colorado Island, Panama. We compare predictions to those of a current VDM, quantitative observations and ecological expectations. We find that the scheme improves the magnitude and rank order of recruitment rates among functional types and captures recruitment limitations in response to variable understory light, soil moisture and precipitation regimes. Furthermore, our results indicate that adopting this framework will improve VDM capacity to predict functional-type-specific tree recruitment in response to climate change, thereby improving predictions of future forest distribution, composition and function.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2023

Method to Investigate Cognitive Aging Effects in Nuclear Operations Using the Rancor Microworld Simulator

Many nuclear power plant (NPP) operators are close to, or at retirement age. Since NPP operators are responsible for tasks that engage different and complex cognitive abilities, human factors researchers recently called for the need to examine cognitive aging effects and potential interactions with modernized control rooms. One way control rooms are being modernized is by replacing paper-based procedures with computer-based procedures (CBPs). This paper outlines a method for testing preference and usability of three types of CBPs as a function of age, in simulated NPP operations. The Rancor Microworld Simulator will be used, which mimics an NPP control room, allowing novices to learn to perform operator tasks quickly. The experiment will have two independent variables: age (young and old) and CBP-type (Type 1, Type 2, and Type 3). The three types of CBPs vary in levels of embedded instrumentation and controls. Adults aged 18–25 years (young group) and =60 years (older group) will be recruited from the general population. The dependent variables will be preference and usability metrics via survey and simulator logs. All participants will perform two scenario types (startup and loss of feedwater operations) and will be randomly assigned to one type of CBP to guide them through the scenario. Analyses of variance (ANOVAs) will be used to determine whether there is a main effect of age and any age x CBP-type interactions on the preference and usability dependent variables.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

NASA NTRS1982

Ship and satellite bio-optical research in the California Bight

Mesoscale biological patterns and processes in productive coastal waters were studied. The physical and biological processes leading to chlorophyll variability were investigated. The ecological and evolutionary significance of this variability, and its relation to the prediction of fish recruitment and marine mammal distributions was studied. Seasonal primary productivity (using chlorophyll as an indication of phytoplankton biomass) for the entire Southern California Bight region was assessed. Complementary and contemporaneous ship and satellite (Nimbus 7-CZCS) bio-optical data from the Southern California Bight and surrounding waters were obtained and analyzed. These data were also utilized for the development of multi-platform sampling strategies and the optimization of algorithms for the estimation of phytoplankton biomass and primary production from satellite imagery.

Smith, R. C.↗

NASA NTRS2010

Preliminary Results of Bisphosphonate ISS Flight Experiment

Bone loss has been recognized as a potential problem from the beginning of human spaceflight. With the spaceflight missions lasting 6 months to potentially 3 years or longer this issue has assumed increased significance. Detailed measurements from the Mir and ISS long duration missions have documented losses in bone mineral density (BMD) from the total skeleton and critical sub-regions. The most important losses are from the femoral hip averaging about -1.6%/mo integral to -2.3%/mo trabecular BMD. Importantly these studies have documented the wide range in individual response from -0.5 to -5%/mo in BMD. Given the small size of any expedition crew, the wide range of responses has to be considered in the implementation of any countermeasure. Assuming that it is unlikely that the susceptibility for bone loss in any given crewmember will be known, a suite of bone loss countermeasures will likely be needed to insure protection of all crewmembers. The hypothesis for this experiment is that the combined effect of anti-resorptive drugs plus the standard in-flight exercise regimen will have a measurable effect on preventing space flight induced bone loss and strength and will reduce renal stone risk. To date, 4 crewmembers have completed the flight portion of the protocol in which crewmembers take a 70-mg alendronate tablet once a week before and during flight, starting 17 days before launch. Compared to previous ISS crewmembers (n=14) not taking alendronate, DXA measurements of the total hip BMD were significantly changed from -1.1 0.5%/mo to 0.04 0.3%/mo (p<0.01); QCT-determined trabecular BMD of the total hip was significantly changed from -2.3 1.0%/mo to -0.3 1.6%/mo (p<0.01). Significance was calculated from a one-tailed t test. While these results are encouraging, the current n (4) is small, and the large SDs indicate that while the means are improved there is still high variability in individual response. Four additional crewmembers have been recruited to participate in this experiment, with expected completion of these flights by late 2011.

LeBlanc, Adrian↗

NASA NTRS2011

Antiresorptive Treatment for Spaceflight Induced Bone Atrophy - Preliminary Results

Detailed measurements from the Mir and ISS long duration missions have documented losses in bone mineral density (BMD) from critical skeletal sub-regions. The most important BMD losses are from the femoral hip, averaging about -1.6%/mo integral to -2.3%/mo trabecular. Importantly these studies have documented the wide range in individual BMD loss from -0.5 to -5%/mo. Associated elevated urinary Ca increases the risk of renal stone formation during flight, a serious impact to mission success. To date, countermeasures have not been satisfactory. The purpose of this study is to determine if the combined effect of anti-resorptive drugs plus the standard in-flight exercise regimen will have a measurable effect on preventing space flight induced bone loss (mass and strength) and reducing renal stone risk. To date, 4 crewmembers have completed the flight portion of the protocol in which crewmembers take a 70-mg alendronate tablet once a week before and during flight, starting 17 days before launch. Compared to previous ISS crewmembers (n=14) not taking alendronate, DXA measurements of the spine, femur neck and total hip were significantly improved from -0.8 +/- 0.5%/mo to 1.0 +/- 1.1%/mo, -1.1 +/- 0.5%/mo to -0.2 +/- 0.3%/mo, -1.1 +/- 0.5%/mo to 0.04 +/- 0.3%/mo respectively. QCT-determined trabecular BMD of the femur neck, trochanter and total hip were significantly improved from -2.7 +/- 1.9%/mo to -0.2 +/- 0.8%/mo, -2.2 +/- 0.9%/mo to -0.3 +/- 1.9%/mo and -2.3 +/- 1.0%/mo to -0.2 +/- 1.8%/mo respectively. Significance was calculated from a one-tailed t test. Resorption markers were unchanged, in contrast to measurements from previous ISS crewmembers that showed typical increases of 50-100% above baseline. Urinary Ca showed no increase compared to baseline levels, also distinct from the elevated levels of 50% or greater in previous crews. While these results are encouraging, the current n (4) is small, and the large SDs indicate that, while the means are improved, there is still high variability in individual response. Three additional crewmembers have been recruited to participate in this experiment, with expected completion in late 2011.

LeBlanc, Adrian↗

NASA NTRSDate not supplied

Defining Change Thresholds: What Change Is Outside Typical Sources of Variation?

Researchers often have a difficult time defining meaningful thresholds for change. We sometimes identify subtle changes but what amount of change is beyond typical sources of variation? This is especially complicated when trying to understand new disease pathogenesis like the constellation of eye changes leading to Spaceflight-associated Neuro-ocular Syndrome (SANS). To support decision makers in defining minimal meaningful change, we used a Bayesian hierarchical model to estimate innate sources of variability such as natural day to day variation. Healthy subjects were recruited and imaged with MRI, OCT, and US on separate days and measured by several technicians. Models were developed specifying random effects for the sources of variation – between left and right eyes, within-individuals over time, between raters, and finally between individuals. This allowed us to find the posterior distribution for the total typical variation, within an eye, which we use to define a threshold where change beyond typical sources of variation is likely. This threshold is now used as our earliest indicator of systematic increase in Total Retinal Thickness (a precursor to optic disc edema).

Millennia Young↗

DOE OSTI2024

Establishing reference ranges for circulating biomarkers of drug‐induced liver injury in healthy human volunteers 1

Aims The potential of mechanistic biomarkers to improve prediction of drug‐induced liver injury (DILI) and hepatic regeneration is widely acknowledged. We sought to determine reference intervals for new biomarkers of DILI and regeneration, as well as to characterize their natural variability and impact of diurnal variation. Methods Serum samples from 227 healthy volunteers were recruited as part of a cross‐sectional study; of these, 25 subjects had weekly serial sampling over 3 weeks, while 23 had intensive blood sampling over a 24h period. Alanine aminotransferase (ALT), MicroRNA‐122 (miR‐122), High Mobility Group Box‐1 (HMGB1), total Keratin‐18 (K18), caspase‐cleaved Keratin‐18 (ccK18), Glutamate Dehydrogenase (GLDH) and Macrophage Colony‐Stimulating Factor‐1 (CSF‐1) were assayed. Results Reference intervals were established for each biomarker based on the 97.5% quantile (90% CI) following the assessment of fixed effects in univariate and multivariable models. Intra‐individual variability was found to be non‐significant, and there was no significant impact of diurnal variation. Conclusion Reference intervals for novel DILI biomarkers have been described. An upper limit of a reference range might represent the most appropriate mechanism to utilize these data. These data can now be used to interpret data from exploratory clinical DILI studies and to assist their further qualification as required by regulatory authorities.

Jorgensen, Andrea L. [Department of Health Data Sc↗

NASA NTRS2019

Coral Reef Annihilation, Persistence and Recovery at Earth’s Youngest Volcanic Island

The structure and function of coral reef ecosystems is increasingly compromised by multiple stressors, even in the most remote locations. Severe, acute disturbances such as volcanic eruptions represent extreme events that can annihilate entire reef ecosystems, but also provide unique opportunities to examine ecosystem resilience and recovery. Here, we examine the destruction, persistence and initial recovery of reefs associated with the hydromagmatic eruption that created Earth’s newest landmass, the Hunga Tonga–Hunga Ha’apai volcanic island. Despite extreme conditions associated with the eruption, impacts on nearby reefs were spatially variable. Importantly, even heavily affected reefs showed signs of rapid recovery driven by high recruitment, likely from local refuges. The remote location and corresponding lack of additional stressors likely contribute to the resilience of Hunga’s reefs, suggesting that in the absence of chronic anthropogenic stressors, coral reefs can be resilient to one of the largest physical disturbances on Earth.

Refuge population↗

DOE OSTI2025

Resilient information and inference networks under mixed-trust sensing

With ubiquitous digitization, sensing, and computational intelligence deployed in increasingly more and broader domains, including critical infrastructure, potentially misleading and destabilizing effects of multimodal anomalies and adversarial behavior are growing in importance. Here, we develop randomized and reinforcement learning-based strategies for strategically recruiting and utilizing deployed (and, thus, vulnerable and potentially faulty and/or compromised) nodes from information and inference networks, while defending against adversaries that attempt to misguide assessments of inferred variables. Recognizing that, besides communication and other costs, sampling from any observable node can either provide true data or dangerously expose our inference to misinformation (without being easily distinguishable what actually happens), the proposed strategies proceed by progressively recruiting nodes and cautiously scaling their information contribution based on assumed, or, in our reinforcement learning approach, intelligently weighed trustworthiness, with the learning approach also considering network-wide, threat-inclusive risk/value tradeoffs. While avoiding the hardware, communication, analytical and computational burden of explicit redundancy, the proposed defensive schemes enable on-the-fly assessments of underlying processes, and system-wide situational awareness with demonstrable resilience against adversarial activities.

97 - MATHEMATICS AND COMPUTING↗

NASA NTRSDate not supplied

Assessing the Relationships Between Sensorimotor Biomarkers and Post-Landing Functional Task Performance

Spaceflight drives adaptive changes in healthy individuals appropriate for sensorimotor function in a microgravity environment. These changes are maladaptive for return to earth's gravity. The inter-individual variability of sensorimotor decrements is striking, although poorly understood. The goal of this study was to identify a set of behavioral, neuroimaging and genetic measures that can be used to predict early post-flight performance on a set of sensorimotor tasks. Astronauts were recruited who previously participated in sensorimotor field tests and/or posturography soon after long-duration spaceflight. Behavioral tests included assessments of sensory dependency and adaptability. Visual dependency involved treadmill walking while viewing a moving virtual visual scene. Vestibular perceptual thresholds were measured while seated during lateral translations. Proprioception dependency was measured during one-legged stance on a horizontal air-bearing surface. Ground assessment of adaptability was performed (1) during treadmill walking with a virtual linear hallway and a moving walking surface, and (2) during multiple trials of navigating an obstacle course while wearing reversing prisms (adaptive Functional Mobility Test, aFMT). The neuroimaging tests characterized individual differences in regional brain volumes (using Structural MRI) and white matter microstructure (using Diffusion Tensor Imaging) to serve as potential predictors of adaptive capacity. The genetic tests utilized saliva samples to examine variations in four genes chosen because of their ability to differentiate sensorimotor adaptation ability in a normative population, including Catechol-O-methyltransferase (COMT), Dopamine Receptor D2 (DRD2), Brain-derived neurotrophic factor (BDNF) and the α2-adrenergic receptor. Thirty ISS crewmembers were recruited, including 12 first-time fliers, 6F, and mission durations lasting 185.5 ± 45.5 days, mean ± std. We utilized a combination of three post-flight functional task outcomes: tandem walk, recovery from fall and dynamic posturography. There was considerable variability among all post-flight performance outcomes. Based on an ordinal scale survey, 72% indicated their ability to perform functional tasks were more impacted postflight relative to inflight with 50% indicating they needed to restrict movements for a longer period postflight relative to inflight. While there is a strong association within tests obtained at different R+0 timepoints, by R+24 hr performance on one post-flight test does not necessarily correlate with performance on other post-flight tests. Preliminary statistical analysis indicates combining biomarkers will increase predictive power and this will be explored with future analyses. Our preliminary findings underscore the importance of a comprehensive post-flight test battery including different types of tasks with varying sensory feedback. Understanding the relationships between these sensorimotor biomarkers and post-flight functional task performance improve both our understanding of the individual variability and our strategy to optimize sensorimotor countermeasures.

biomarkers↗

NASA NTRS1975

Demographic and psychological variables affecting test subject evaluations of ride quality

Ride-quality experiments similar in objectives, design, and procedure were conducted, one using the U.S. Air Force Total In-Flight Simulator and the other using the Langley Passenger Ride Quality Apparatus to provide the motion environments. Large samples (80 or more per experiment) of test subjects were recruited from the Tidewater Virginia area and asked to rate the comfort (on a 7-point scale) of random aircraft motion typical of that encountered during STOL flights. Test subject characteristics of age, sex, and previous flying history (number of previous airplane flights) were studied in a two by three by three factorial design. Correlations were computed between one dependent measure, the subject's mean comfort rating, and various demographic characteristics, attitudinal variables, and the scores on Spielberger's State-Trait Anxiety Inventory. An effect of sex was found in one of the studies. Males made higher (more uncomfortable) ratings of the ride than females. Age and number of previous flights were not significantly related to comfort ratings. No significant interactions between the variables of age, sex, or previous number of flights were observed.

Duncan, N. C.↗

DOE OSTI2025

National serosurvey and risk mapping reveal widespread distribution of Coxiella burnetii in Kenya

Coxiella burnetii, the causative agent of Q fever, is an emerging pathogen that has the potential to cause severe chronic infections in animals and humans worldwide. The detrimental impact on public health is projected to be higher in the low- and middle-income countries given their lower capacity to sustain effective surveillance and response measures. We implemented a national serosurvey of cattle in Kenya to map the spatial distribution of the pathogen. The study used serum samples that were collected from randomly selected cattle in different ago-ecological zones across the country. These samples were screened for the pathogen using PrioCHECK Ruminant Q Fever AB Plate ELISA kit. The laboratory findings were analyzed using INLA package to identify risk factors for C. burnetii exposure from herd- and animal-level factors, area, and bioclimatic datasets accessed from online databases. A total of 6,593 cattle were recruited for the study; of these, 7.9% (95% CI; 7.2–8.5) were seropositive. Outputs from the multivariable analysis revealed that the animal age and some of the geographical variables including wind speed, area under shrubs and “petric calcisols” type of soil were significantly associated with C. burnetii seropositivity. Being a calf, weaner or subadult was associated with lower odds of exposure compared to being an adult by 0.24 (credibility interval: 2.5% and 97.5%), 0.41 (0.30–0.55) and 0.51 (0.38–0.69), respectively. In addition, a unit increase in the wind speed increased the odds of C. burnetii seropositivity by 1.27 (1.05–1.52) while an increase on the land area under shrubs was associated with lower odds of exposure (0.67 [0.47–0.69]). The effect of petric calcisols was non-linear; an increase of the land area with this soil type was associated with an exponential increase in C. burnetii seropositivity. This study provides new data on C. burnetii seroprevalence, information of its risk factors and a prevalence map that can be used for C. burnetii risk surveillance and control. The identification of environmental risk factors for C. burnetii exposure, and the increasing awareness of the zoonotic potential of the pathogen, calls for the need to enhance the existing collaborations for the surveillance and control of C. burnetii in line with the One Health framework. The evidence generated on the potential role of environmental factors can also be used to design nature-based interventions, such as replacement of vegetation in denuded areas, to reduce potential for the aerosolization of the pathogen. Livestock vaccination in the hotspots would also reduce animal infections and hence the contamination of the environment.

60 APPLIED LIFE SCIENCES↗

NASA NTRS2007

The NASA-Sponsored Study of Cataract in Astronauts (NASCA). Relationship of Exposure to Radiation in Space and the Risk of Cataract Incidence and Progression. Report 1: Recruitment and Methodology

The NASA Study of Cataract in Astronauts (NASCA) is a five-year, multi-centered, investigation of lens opacification in populations of U.S. astronauts, military pilots, and ground-based (nonaviator) comparison participants. For astronauts, the explanatory variable of most interest is radiation exposure during space flight, however to properly evaluate its effect, the secondary effects of age, nutrition, general health, solar ocular exposure, and other confounding variables encountered in non-space flight must also be considered. NASCA contains an initial baseline, cross-sectional objective assessment of the severity of cortical (C), nuclear (N), and posterior subcapsular (PSC) lens opacification, and annual follow-on assessments of severity and progression of these opacities in the population of astronauts and in participants sampled from populations of military pilots and ground-based exposure controls. From these data, NASCA will estimate the degree to which space radiation affects lens opacification for astronauts and how the overall risks of each cataract type for astronauts compared with those of the other exposure control groups after adjusting for differences in age and other explanatory variables.

Chylack, Leo T.↗

DOE OSTI2022

Dual Targeting Factors Are Required for LXG Toxin Export by the Bacterial Type VIIb Secretion System

Bacterial type VIIb secretion systems (T7SSb) are multisubunit integral membrane protein complexes found in Firmicutes that play a role in both bacterial competition and virulence by secreting toxic effector proteins. The majority of characterized T7SSb effectors adopt a polymorphic domain architecture consisting of a conserved N-terminal Leu-X-Gly (LXG) domain and a variable C-terminal toxin domain. Recent work has started to reveal the diversity of toxic activities exhibited by LXG effectors; however, little is known about how these proteins are recruited to the T7SSb apparatus. In this work, we sought to characterize genes encoding domains of unknown function (DUFs) 3130 and 3958, which frequently cooccur with LXG effector-encoding genes. Using coimmunoprecipitation-mass spectrometry analyses, in vitro copurification experiments, and T7SSb secretion assays, we found that representative members of these protein families form heteromeric complexes with their cognate LXG domain and in doing so, function as targeting factors that promote effector export. Additionally, an X-ray crystal structure of a representative DUF3958 protein, combined with predictive modeling of DUF3130 using AlphaFold2, revealed structural similarity between these protein families and the ubiquitous WXG100 family of T7SS effectors. Interestingly, we identified a conserved FxxxD motif within DUF3130 that is reminiscent of the YxxxD/E “export arm” found in mycobacterial T7SSa substrates and mutation of this motif abrogates LXG effector secretion. Overall, our data experimentally link previously uncharacterized bacterial DUFs to type VIIb secretion and reveal a molecular signature required for LXG effector export.

24 antibacterial toxins↗