Dual-task interference of reactive stepping kinematics for balance recovery strategies in older adults.

OBJECTIVE: To characterize the interference of reactive stepping kinematics related to the increase or maintenance of the number of steps in response to a large perturbation during dual tasks among older adults. METHODS: This was a cross-sectional study that included 52 community-dwelling healthy older adults. Reactive stepping performance was analyzed after forward balance loss during a single task and a second cognitive task. The number of steps taken to recover balance and dual-task interference (DTI) for muscular onset latency, anteroposterior (AP) center of pressure (COP) displacement and velocity before step initiation, and step temporal and spatial variables were measured. The DTI of the variables was compared between the participants who increased versus those who maintained the number of steps taken during the dual task relative to the single task. RESULTS: Twenty-eight (53.8 %) participants increased their steps during dual tasks relative to a single task. In older adults, the AP COP peak velocity (P < 0.001) and step length (P < 0.001) were significantly worse during dual tasks than during a single task. However, this was not observed for older adults who did not increase their steps. The DTI for the AP COP peak velocity and step length were significantly larger for the older adults who increased their steps than those who did not (AP COP peak velocity; P = 0.044, step length; P = 0.003). Both groups showed a significant muscular onset delay during dual tasks than during a single task (P < 0.001), and no significant differences were found between the groups. CONCLUSIONS: Our findings suggest that reactive stepping strategies in older adults after a large external perturbation during secondary cognitive tasks can be attributed to interference with COP control before step initiation and step length.

Microbes guide corals looking to find a home.

Coral reefs are facing unprecedented anthropogenic pressures impacting critical processes such as recruitment of juvenile corals. Through larval choice assays and co-occurrence network analyses, a recent study by Turnlund et al. identified microbial taxa within reef biofilms that positively correlate and therefore have potential key roles in inducing coral settlement.

Physical activity is associated with walking and balance ability but not fatigue, knee extension strength, or body composition in adults with cerebral palsy: a pilot cross-sectional study.

Common secondary impairments associated with aging in adults with cerebral palsy (CP) decrease physical functions, including walking and balance ability, and increase the sense of fatigue. This motor dysfunction results in decreased physical activity (PA) and could be associated with obesity and sarcopenia. This study examined the association of daily PA levels with fatigue, physical function, and body composition in 22 adults with CP (age, 37.4 ±â€…14.7 years; Gross Motor Function Classification System level, I: 6, II: 16). The level of daily PA was divided into percent of sedentary behavior, light PA, and moderate-to-vigorous PA (%MVPA) per day. These outcomes were examined for correlation with the Fatigue Severity Scale, knee extension strength, comfortable and maximum walking speed, Timed-Up-and-Go-Test (TUG), and body fat percentage and skeletal muscle mass using Spearman's rank correlation coefficient. An additional partial correlation analysis with sex and age adjustment was performed. The %MVPA correlated positively with comfortable walking speed (rs = 0.424, P  = 0.049) and negatively with TUG (rs = -0.493, P  = 0.020). The partial correlation revealed associations of %MVPA with maximum walking speed (r = 0.604, P  = 0.022) and TUG (r = -0.604, P  = 0.022). The results show that among adults with CP, increased PA is associated with improvements in mobility but not in perceived fatigue or body composition, regardless of sex and age. Maintaining and improving %MVPA and walking and balance ability in adults with CP have a positive impact on each other, and potentially on overall health management.

MLPK function is not required for self-incompatibility in the S29 haplotype of Brassica rapa L.

KEY MESSAGE: S29 haplotype does not require the MLPK function for self-incompatibility in Brassica rapa. Self-incompatibility (SI) in Brassicaceae is regulated by the self-recognition mechanism, which is based on the S-haplotype-specific direct interaction of the pollen-derived ligand, SP11/SCR, and the stigma-side receptor, SRK. M locus protein kinase (MLPK) is known to be one of the positive effectors of the SI response. MLPK directly interacts with SRK, and is phosphorylated by SRK in Brassica rapa. In Brassicaceae, MLPK was demonstrated to be essential for SI in B. rapa and Brassica napus, whereas it is not essential for SI in Arabidopsis thaliana (with introduced SRK and SP11/SCR from related SI species). Little is known about what determines the need for MLPK in SI of Brassicaceae. In this study, we investigated the relationship between S-haplotype diversity and MLPK function by analyzing the SI phenotypes of different S haplotypes in a mlpk/mlpk mutant background. The results have clarified that in B. rapa, all the S haplotypes except the S29 we tested need the MLPK function, but the S29 haplotype does not require MLPK for the SI. Comparative analysis of MLPK-dependent and MLPK-independent S haplotype might provide new insight into the evolution of S-haplotype diversity and the molecular mechanism of SI in Brassicaceae.

Microbial mat compositions and localization patterns explain the virulence of black band disease in corals.

Black band disease (BBD) in corals is characterized by a distinctive, band-like microbial mat, which spreads across the tissues and often kills infected colonies. The microbial mat is dominated by cyanobacteria but also commonly contains sulfide-oxidizing bacteria (SOB), sulfate-reducing bacteria (SRB), and other microbes. The migration rate in BBD varies across different environmental conditions, including temperature, light, and pH. However, whether variations in the migration rates reflect differences in the microbial consortium within the BBD mat remains unknown. Here, we show that the micro-scale surface structure, bacterial composition, and spatial distribution differed across BBD lesions with different migration rates. The migration rate was positively correlated with the relative abundance of potential SOBs belonging to Arcobacteraceae localized in the middle layer within the mat and negatively correlated with the relative abundance of other potential SOBs belonging to Rhodobacteraceae. Our study highlights the microbial composition in BBD as an important determinant of virulence.

Developmental changes in straight gait in childhood.

BACKGROUND: Understanding typical gait development is critical in developing suitable physical therapy methods for gait disorders. This study investigated the developmental changes and controlling mechanisms of straight gait. METHODS: We conducted an experimental procedure among 90 participants, including 76 typically developing children and 14 healthy adults. The children were divided according to age into 3-4, 5-6, 7-8, and 9-10-year age groups. We created two indices to quantify straight gait using the extrapolated center of mass (XCOM; goal index, XCOMG and actual progress index, XCOMP), which were calculated and compared between the groups. Stepwise multiple regression was used to examine the effects of each gait variable on XCOMG and XCOMP. To eliminate the effects of multicollinearity, correlation coefficients were calculated for all gait variables. RESULTS: Both XCOMG and XCOMP decreased gradually with age and were significantly larger in the 3-4 and 5-6 year groups than in the adult group. Multiple regression analysis showed that step velocity, step width, and the coefficiente of variation (CV) of the step width had independent coefficients of variation for the XCOMG, and the symmetry index of step time, step width, and the CV of the step width had independent CV for the XCOMP. These variables were selected as significant variables. The results showed that meandering gait was more pronounced at younger ages. Furthermore, straight gait observed in adulthood was achieved by the age of 7. CONCLUSION: Pace (step velocity) and stability (step width and CV of step width) may contribute to XCOMG, which assesses the ability to proceed in the direction of the target. Stability and symmetry may contribute to XCOMP, which assesses the ability to walk straight in one's own direction of progress. Physical therapists could apply these indices in children to assess their ability to walk straight.

Effects of Fear of Falling on the Single-Step Threshold for Lateral Balance Recovery in Older Women.

BACKGROUND AND PURPOSE: Fear of falling is associated with poor physical health and influences postural stability during whole-body movement. The ability to recover from lateral balance loss is required to prevent falls; however, the relationship between lateral balance recovery and fear of falling has not been established. This study aimed to investigate whether fear of falling is associated with the stepping threshold for lateral balance recovery. METHODS: This study included 56 ambulatory, community-dwelling women aged 65 years or older. We determined the single-step threshold as the maximum lean magnitude normalized with body weight from which participants could be suddenly released and still recover balance using a single side step. The short-form Falls Efficacy Scale International was used as a measure of fear of falling. RESULTS AND DISCUSSION: The single-step threshold significantly correlated with age ( rs =-0.603) and the short-form Falls Efficacy Scale International score ( rs =-0.439). Ordinal regression analysis revealed that age (odds ratio, 0.826; 95% confidence interval, 0.742-0.920) and the short-form Falls Efficacy Scale International score (odds ratio, 0.811; 95% confidence interval, 0.680-0.966) were significantly associated with the single-step threshold, such that older age and greater fear of falling each independently predicted that failure to recover balance with a single step would occur at a lower percentage of body weight. CONCLUSIONS: Greater fear of falling was associated with reduced ability to recover from lateral balance loss in addition to aging. Future studies should explore whether evidence-based interventions to reduce fear of falling combined with perturbation training might lead to improved ability to recover from balance loss.

Fidelity varies in the symbiosis between a gutless marine worm and its microbial consortium.

BACKGROUND: Many animals live in intimate associations with a species-rich microbiome. A key factor in maintaining these beneficial associations is fidelity, defined as the stability of associations between hosts and their microbiota over multiple host generations. Fidelity has been well studied in terrestrial hosts, particularly insects, over longer macroevolutionary time. In contrast, little is known about fidelity in marine animals with species-rich microbiomes at short microevolutionary time scales, that is at the level of a single host population. Given that natural selection acts most directly on local populations, studies of microevolutionary partner fidelity are important for revealing the ecological and evolutionary processes that drive intimate beneficial associations within animal species. RESULTS: In this study on the obligate symbiosis between the gutless marine annelid Olavius algarvensis and its consortium of seven co-occurring bacterial symbionts, we show that partner fidelity varies across symbiont species from strict to absent over short microevolutionary time. Using a low-coverage sequencing approach that has not yet been applied to microbial community analyses, we analysed the metagenomes of 80 O. algarvensis individuals from the Mediterranean and compared host mitochondrial and symbiont phylogenies based on single-nucleotide polymorphisms across genomes. Fidelity was highest for the two chemoautotrophic, sulphur-oxidizing symbionts that dominated the microbial consortium of all O. algarvensis individuals. In contrast, fidelity was only intermediate to absent in the sulphate-reducing and spirochaetal symbionts with lower abundance. These differences in fidelity are likely driven by both selective and stochastic forces acting on the consistency with which symbionts are vertically transmitted. CONCLUSIONS: We hypothesize that variable degrees of fidelity are advantageous for O. algarvensis by allowing the faithful transmission of their nutritionally most important symbionts and flexibility in the acquisition of other symbionts that promote ecological plasticity in the acquisition of environmental resources. Video Abstract.

Differential regulation of degradation and immune pathways underlies adaptation of the ectosymbiotic nematode Laxus oneistus to oxic-anoxic interfaces.

Eukaryotes may experience oxygen deprivation under both physiological and pathological conditions. Because oxygen shortage leads to a reduction in cellular energy production, all eukaryotes studied so far conserve energy by suppressing their metabolism. However, the molecular physiology of animals that naturally and repeatedly experience anoxia is underexplored. One such animal is the marine nematode Laxus oneistus. It thrives, invariably coated by its sulfur-oxidizing symbiont Candidatus Thiosymbion oneisti, in anoxic sulfidic or hypoxic sand. Here, transcriptomics and proteomics showed that, whether in anoxia or not, L. oneistus mostly expressed genes involved in ubiquitination, energy generation, oxidative stress response, immune response, development, and translation. Importantly, ubiquitination genes were also highly expressed when the nematode was subjected to anoxic sulfidic conditions, together with genes involved in autophagy, detoxification and ribosome biogenesis. We hypothesize that these degradation pathways were induced to recycle damaged cellular components (mitochondria) and misfolded proteins into nutrients. Remarkably, when L. oneistus was subjected to anoxic sulfidic conditions, lectin and mucin genes were also upregulated, potentially to promote the attachment of its thiotrophic symbiont. Furthermore, the nematode appeared to survive oxygen deprivation by using an alternative electron carrier (rhodoquinone) and acceptor (fumarate), to rewire the electron transfer chain. On the other hand, under hypoxia, genes involved in costly processes (e.g., amino acid biosynthesis, development, feeding, mating) were upregulated, together with the worm's Toll-like innate immunity pathway and several immune effectors (e.g., bactericidal/permeability-increasing proteins, fungicides). In conclusion, we hypothesize that, in anoxic sulfidic sand, L. oneistus upregulates degradation processes, rewires the oxidative phosphorylation and reinforces its coat of bacterial sulfur-oxidizers. In upper sand layers, instead, it appears to produce broad-range antimicrobials and to exploit oxygen for biosynthesis and development.

Spatiotemporal Characteristics of Lateral Reactive Stepping in Individuals with Chronic Stroke.

We compared the spatiotemporal characteristics of lateral perturbation-induced reactive stepping in stroke subjects with those of age-matched controls. We subjected 12 stroke subjects and 17 healthy elderly controls to lateral stepping. We analyzed first-step spatiotemporal parameters during stepping and recorded the selected reactive step types at the stepping threshold. Stroke subjects showed a lower stepping threshold and more frequently used medial steps than controls. Stroke subjects also had a longer delay prior to foot-off in lateral steps when perturbed toward the nonparetic side, and in medial steps when perturbed toward both sides than controls. Thus, the time deficits in reactive stepping in individuals with stroke may be attributed to stroke-related sensorimotor impairments, indicating their limitations in balance control.