Effects of Stroboscopic Vision on Depth Jump Motor Control: A Biomechanical Analysis

Researchers commonly use the 'free-fall' paradigm to investigate motor control during landing impacts, particularly in drop landings and depth jumps (DJ). While recent studies have focused on the impact of vision on landing motor control, previous research fully removed continuous visual input, limiting ecological validity. The aim of this investigation was to evaluate the effects of stroboscopic vision on depth jump (DJ) motor control. Ground reaction forces (GRF) and lower-extremity surface electromyography (EMG) were collected for 20 young adults (11 male; 9 female) performing six depth jumps (0.51 m drop height) in each of two visual conditions (full vision vs. 3 Hz stroboscopic vision). Muscle activation magnitude was estimated from EMG signals using root-mean-square amplitudes (RMS) over specific time intervals (150 ms pre-impact; 30-60 ms, 60-85 ms, and 85-120 ms post-impact). The main effects of and interactions between vision and trial number were assessed using two-way within-subjects repeated measures analyses of variance. Peak GRF was 6.4% greater, on average, for DJs performed with stroboscopic vision compared to full vision (p = 0.042). Tibialis anterior RMS EMG during the 60-85 ms post-impact time interval was 14.1% lower for DJs performed with stroboscopic vision (p = 0.020). Vastus lateralis RMS EMG during the 85-120 ms post-impact time interval was 11.8% lower for DJs performed with stroboscopic vision (p = 0.017). Stroboscopic vision altered DJ landing mechanics and lower-extremity muscle activation. The observed increase in peak GRF and reduction in RMS EMG of the tibialis anterior and vastus lateralis post-landing may signify a higher magnitude of lower-extremity musculotendinous stiffness developed pre-landing. The results indicate measurable sensorimotor disruption for DJs performed with stroboscopic vision, warranting further research and supporting the potential use of stroboscopic vision as a sensorimotor training aid in exercise and rehabilitation. Stroboscopic vision could induce beneficial adaptations in multisensory integration, applicable to restoring sensorimotor function after injury and preventing injuries in populations experiencing landing impacts at night (e.g., military personnel).

Leaf growth - complex regulation of a seemingly simple process

Understanding the underlying mechanisms of plant development is crucial to successfully steer or manipulate plant growth in a targeted manner. Leaves, the primary sites of photosynthesis, are vital organs for many plant species, and leaf growth is controlled by a tight temporal and spatial regulatory network. In this review, we focus on the genetic networks governing leaf cell proliferation, one major contributor to final leaf size. First, we provide an overview of six regulator families of leaf growth in Arabidopsis: DA1, PEAPODs, KLU, GRFs, the SWI/SNF complexes, and DELLAs, together with their surrounding genetic networks. Next, we discuss their evolutionary conservation to highlight similarities and differences among species, because knowledge transfer between species remains a big challenge. Finally, we focus on the increase in knowledge of the interconnectedness between these genetic pathways, the function of the cell cycle machinery as their central convergence point, and other internal and environmental cues.

Identification and expression analysis of miR396 and its target genes in Jerusalem artichoke under temperature stress

The highly conserved miR396 plays a pivotal role in the growth, development, and responses to abiotic and biotic stresses in plants. However, research on miR396 and its targets in Jerusalem artichoke remains largely unexplored. In this study, we employed bioinformatics and experimental techniques, such as cloning and qRT-PCR, to investigate the regulatory role of miR396 on its targets, leveraging our lab's transcriptomic and degradomic data of Jerusalem artichoke. Specifically, we initially cloned and characterized the precursors (htu-MIR396a/b/c) and mature sequences (htu-miR396a/b/c) of three miR396 isoforms. Subsequently, we identified nine target genes, including seven Growth-Regulating Factors (GRFs) (HtGRF3/4/6/9/10/12/13), one WRKY transcription factor (HtWRKY40), and one Scarecrow-like (SCL) transcription factor (HtSCL33). Finally, we conducted an analysis of their expression patterns across various tissues and their responses to temperature stress. Notably, htu-MIR396s exhibited high expression in seedling stems, while htu-miR396s predominantly expressed in seedling leaves. Moreover, HtWRKY40 and HtSCL33 displayed higher expression levels than HtGRFs in most tissues, except leaves. Remarkably, HtGRF4/6/10/12/13 exhibited higher expression in leaves than in roots and stems during seedling growth. Furthermore, during tuber development, HtGRF4/6/10, HtWRKY40, and HtSCL33 were highly expressed, while HtGRF3/9/12/13 showed relatively lower expression levels. Under heat stress (42℃), htu-MIR396 expression was up-regulated, and htu-miR396 showed dynamic expression patterns in seedlings, resulting in the induction of HtGRF4/6/10/12/13 in leaves and HtSCL33 in roots, while HtWRKY40 in leaves was repressed. Conversely, under cold stress (4℃), htu-MIR396s showed fluctuating expression levels, and htu-miR396s were up-regulated in seedlings. Notably, HtGRF4/13 and HtSCL33 in seedlings were reduced, whereas HtGRF6 in roots and HtWRKY40 in leaves were enhanced. These findings offer valuable insights into the functional roles of miR396-target interactions under abiotic stress in Jerusalem artichoke.

A Prospective Study of Graft Repositioning over Flap Technique for Reconstruction of Fingertip Amputation

Background: Replantation of digital tip amputations, especially Allen III and IV, is challenging for hand surgeons as it requires a high level of microsurgical expertise and fine instruments. The graft repositioning over flap (GRF) technique is a simple and reliable procedure that provides length, sensation and nail growth and GRF has become popular in the last few years. The aim of this study is to report the short-term outcomes of the GRF technique. Methods: This is a prospective study of all patients who underwent a GRF reconstruction for Allen III and IV digital amputations at our hospital over a 12-month period. In addition to demographic data and injury details, we collected outcomes data with regard to flap and nailbed graft survival, capillary refill time, nail growth, sensation (2-point discrimination), bone union and gain in length of digit compared to length at injury. Results: Twenty patients underwent GRF reconstruction of digital amputation. They included 18 men and 2 women with an average age of 29 years. The thumb was the most frequently injured digit (n = 7). Electric saws (n = 5) and industrial machines (n = 5) accounted for 50% of injuries. Twelve amputations were Allen IV. Five patients were lost to follow-up and outcomes data was available for 15 patients. There was loss of flap and nail bed in three patients. There was no growth of nail in three patients. The distal phalanx graft was lost in six patients and united in the remaining nine patients. Conclusions: The GRF technique is a simple and reliable option in patients in whom replantation is not possible. It restores length, provides sensation and nail growth in the reconstructed fingers. Level of Evidence: Level IV (Therapeutic).

Drought priming modulates ABF, GRFs, related microRNAs and induce metabolic adjustment during heat stress in chickpea

Drought and high temperature stress may occur concomitantly or individually in succession causing cellular dysfunctions. Abscisic acid (ABA) is a key stress regulator, and its responsive genes are controlled by ABRE (Abscisic acid Responsive Element)-binding factors (ABFs)and G-Box Regulatory factors (GRFs). Here, we identify ABFs, GRFs and targeting miRNAs in desi and kabuli chickpea. To validate their role after drought priming and subsequent high temperature stress, two contrasting chickpea varieties (PBG1 and PBG5) were primed and exposed to 32 °C, 35 °C and 38 °C for 12, 6 and 2 h respectively and analyzed for Physio-biochemical, expression of ABFs, GRFs and MiRNAs, and GC-MS based metabolite analysis. To ascertain the ABF-GRF protein-protein interactions, docking studies were carried out between the ABF3 and GRF14. Genome-wide analysis identified total 9 & 11 ABFs, and 11 GRFsin desi and kabuli respectively. Their gene structure, and motif composition were conserved in all subfamilies and only 10 and 12 genes have undergone duplication in both desi and kabuli chickpea respectively. These genes were differentially expressed in-silico. MiR172 and miR396 were identified to target ABFs and GRFs respectively. Protein-protein interaction (ABF3 and GRF14) might be successful only when the ABF3 was phosphorylated. Drought priming downregulated miR172 and miR396 and eventually upregulated targeting ABFs, and GRFs. Metabolite profiling (GC-MS) revealed the accumulation of 87 metabolites in Primed (P) and Non-Primed (NP) Chickpea plants. Tolerant cultivar (PBG5) responded better in all respects however both severity of stress and exposure are important factors and can produce broadly similar cellular response.

Genome-Wide Identification and Evolution of the GRF Gene Family and Functional Characterization of PbGRF18 in Pear

Proteins encoded by the G-box regulating factor (GRF, also called 14-3-3) gene family are involved in protein-protein interactions and mediate signaling transduction, which play important roles in plant growth, development, and stress responses. However, there were no detailed investigations of the GRF gene family in pear at present. In this study, we identified 25 GRF family members in the pear genome. Based on a phylogenetic analysis, the 25 GRF genes were clustered into two groups; the ε group and the non-ε group. Analyses of the exon-intron structures and motifs showed that the gene structures were conserved within each of the ε and non-ε groups. Gene duplication analysis indicated that most of the PbGRF gene expansion that occurred in both groups was due to WGD/segmental duplication. Phosphorylation sites analysis showed that the main phosphorylation sites of PbGRF proteins were serine residues. For gene expression, five PbGRF genes (PbGRF7, PbGRF11, PbGRF16, PbGRF21, and PbGRF23) were highly expressed in fruits, and PbGRF18 was highly expressed in all tissues. Further analysis revealed that eight PbGRF genes were significantly differentially expressed after treatment with different sugars; the expression of PbGRF7, PbGRF8, and PbGRF11 significantly increased, implying the involvement of these genes in sugar signaling. In addition, subcellular localization studies showed that the tested GRF proteins localize to the plasma membrane, and transgenic analysis showed that PbGRF18 can increase the sugar content in tomato leaves and fruit. The results of our research establish a foundation for functional determination of PbGRF proteins, and will help to promote a further understanding of the regulatory network in pear fruit development.

Comparatively Evolution and Expression Analysis of GRF Transcription Factor Genes in Seven Plant Species

Growth regulatory factors (GRF) are plant-specific transcription factors that play pivotal roles in growth and various abiotic stresses regulation. However, adaptive evolution of GRF gene family in land plants are still being elucidated. Here, we performed the evolutionary and expression analysis of GRF gene family from seven representative species. Extensive phylogenetic analyses and gene structure analysis revealed that the number of genes, QLQ domain and WRC domain identified in higher plants was significantly greater than those identified in lower plants. Besides, dispersed duplication and WGD/segmental duplication effectively promoted expansion of the GRF gene family. The expression patterns of GRF gene family and target genes were found in multiple floral organs and abundant in actively growing tissues. They were also found to be particularly expressed in response to various abiotic stresses, with stress-related elements in promoters, implying potential roles in floral development and abiotic stress. Our analysis in GRF gene family interaction network indicated the similar results that GRFs resist to abiotic stresses with the cooperation of other transcription factors like GIFs. This study provides insights into evolution in the GRF gene family, together with expression patterns valuable for future functional researches of plant abiotic stress biology.

Overexpression of peanut (Arachis hypogaea L.) AhGRFi gene enhanced root growth inhibition under exogenous NAA treatment in Arabidopsis thaliana

The 14-3-3 protein is a kind of evolutionary ubiquitous protein family highly conserved in eukaryotes. Initially, 14-3-3 proteins were reported in mammalian nervous tissues, but in the last decade, their role in various metabolic pathways in plants established the importance of 14-3-3 proteins. In the present study, a total of 22 14-3-3 genes, also called general regulatory factors (GRF), were identified in the peanut (Arachis hypogaea) genome, out of which 12 belonged to the ε group, whereas 10 of them belonged to the non- ε-group. Tissue-specific expression of identified 14-3-3 genes were studied using transcriptome analysis. The peanut AhGRFi gene was cloned and transformed into Arabidopsis thaliana. The investigation of subcellular localization indicated that AhGRFi is localized in the cytoplasm. Overexpression of the AhGRFi gene in transgenic Arabidopsis showed that under exogenous 1-naphthaleneacetic acid (NAA) treatment, root growth inhibition in transgenic plants was enhanced. Further analysis indicated that the expression of auxin-responsive genes IAA3, IAA7, IAA17, and SAUR-AC1 was upregulated and GH3.2 and GH3.3 were downregulated in transgenic plants, but the expression of GH3.2, GH3.3, and SAUR-AC1 showed opposite trends of change under NAA treatment. These results suggest that AhGRFi may be involved in auxin signaling during seedling root development. An in-depth study of the molecular mechanism of this process remains to be further explored.

Normative spatiotemporal and ground reaction force data for female and male sprinting

This study aimed to demonstrate the differences in spatiotemporal and ground reaction force (GRF) variables during overground sprinting between performance levels for female and male sprinters with providing normative data during the entire acceleration phase. Forty-four female and 102 male sprinters performed 60-m sprints, during which the spatiotemporal and GRF variables were obtained using a long force platform system. Female and male sprinters were each allocated into four groups based on their maximal speed (7.5-9.5 m/s and 8.5-10.5 m/s, respectively) with 0.5 m/s intervals, and average values for 50-m distance were calculated. Using the GRF data, normative data for four groups of female and male sprinters were successfully obtained. For female sprinters using average values of all steps, there were differences between performance levels for step frequency (SF) and support time (ST), all impulses, and all mean forces. For male sprinters using average values of all steps, there were differences between performance levels for SF, ST and flight time, all impulses except for braking impulse, and all of the mean forces. The normative data indicate that most of the spatiotemporal and GRF variables may be changed, particularly increasing SF and propulsive force, when sprint performance is improved.

Genome-wide identification of BcGRF genes in flowering Chinese cabbage and preliminary functional analysis of BcGRF8 in nitrogen metabolism

Growth-regulating factors (GRFs) are a unique family of transcription factors with well-characterized functions in plant growth and development. However, few studies have evaluated their roles in the absorption and assimilation of nitrate. In this study, we characterized the GRF family genes of flowering Chinese cabbage (Brassica campestris), an important vegetable crop in South China. Using bioinformatics methods, we identified BcGRF genes and analyzed their evolutionary relationships, conserved motifs, and sequence characteristics. Through genome-wide analysis, we identified 17 BcGRF genes distributed on seven chromosomes. A phylogenetic analysis revealed that the BcGRF genes could be categorized into five subfamilies. RT-qPCR analysis showed that BcGRF1, 8, 10, and 17 expression clearly increased in response to nitrogen (N) deficiency, particularly at 8 h after treatment. BcGRF8 expression was the most sensitive to N deficiency and was significantly correlated with the expression patterns of most key genes related to N metabolism. Using yeast one-hybrid and dual-luciferase assays, we discovered that BcGRF8 strongly enhances the driving activity of the BcNRT1.1 gene promoter. Next, we investigated the molecular mechanism by which BcGRF8 participates in nitrate assimilation and N signaling pathways by expressing it in Arabidopsis. BcGRF8 was localized in the cell nucleus and BcGRF8 overexpression significantly increased the shoot and root fresh weights, seedling root length, and lateral root number in Arabidopsis. In addition, BcGRF8 overexpression considerably reduced the nitrate contents under both nitrate-poor and -rich conditions in Arabidopsis. Finally, we found that BcGRF8 broadly regulates genes related to N uptake, utilization, and signaling. Our results demonstrate that BcGRF8 substantially accelerates plant growth and nitrate assimilation under both nitrate-poor and -rich conditions by increasing the number of lateral roots and the expression of genes involved in N uptake and assimilation, providing a basis for crop improvement.

GRF-GIF chimeric proteins enhance in vitro regeneration and Agrobacterium-mediated transformation efficiencies of lettuce (Lactuca spp.)

KEY MESSAGE

GRF-GIF chimeric proteins from multiple source species enhance in vitro regeneration in both wild and cultivated lettuce. In addition, they enhance regeneration in multiple types of lettuce including butterheads, romaines, and crispheads. The ability of plants to regenerate in vitro has been exploited for use in tissue culture systems for plant propagation, plant transformation, and genome editing. The success of in vitro regeneration is often genotype dependent and continues to be a bottleneck for Agrobacterium-mediated transformation and its deployment for improvement of some crop species. Manipulation of transcription factors that play key roles in plant development such as BABY BOOM, WUSCHEL, and GROWTH-REGULATING FACTORs (GRFs) has improved regeneration and transformation efficiencies in several plant species. Here, we compare the efficacy of GRF-GIF gene fusions from multiple species to boost regeneration efficiency and shooting frequency in four genotypes of wild and cultivated lettuce (Lactuca spp. L.). In addition, we show that GRF-GIFs with mutated miRNA 396 binding sites increase regeneration efficiency and shooting frequency when compared to controls. We also present a co-transformation strategy for increased transformation efficiency and recovery of transgenic plants harboring a gene of interest. This strategy will enhance the recovery of transgenic plants of other lettuce genotypes and likely other crops in the Compositae family.

Ground reaction forces during double limb stances while walking in individuals with unilateral transfemoral amputation

The asymmetrical gait of individuals with unilateral transfemoral amputation has been well documented. However, there is not a wealth of investigation into asymmetries during the double limb stance depending on whether the intact or prosthetic limb is leading. The first aim of this study was to compare ground reaction forces during the double limb stance of individuals with unilateral transfemoral amputation depending on whether their intact (initial double limb stance) or prosthetic (terminal double limb stance) limb was leading. The second aim of this study was to compare the asymmetry ratio of ground reaction forces during the double limb stance between individuals with and without unilateral transfemoral amputation. Thirty individuals, fifteen with unilateral transfemoral amputation and fifteen who were able-bodied, were recruited for this study. Each individual walked on an instrumented treadmill for 30 s at eight different speeds, ranging from 2.0 km/h to 5.5 km/h with .5 km/h increments. Ground reaction force parameters, temporal parameters, and asymmetry ratios of all parameters were computed from the data collected. The appropriate statistical analyses of all data based on normality were conducted to investigate the aims of this study. Significant main effects of speed, double limb stance, and their interactions were found for most parameters (p < .01 or p < .05). Individuals with unilateral transfemoral amputation spent a longer duration in terminal double limb stance than initial double limb stance at all tested speeds. They also experienced significantly higher peak vertical ground reaction force during initial double limb stance compared to terminal double limb stance with increasing walking speed. However, during terminal double limb stance, higher anteroposterior ground reaction force at initial contact was found when compared to initial double limb stance. Significant differences between individuals with unilateral transfemoral amputation and able-bodied individuals were found in asymmetry ratios for peak vertical ground reaction force, anteroposterior ground reaction force, anteroposterior shear, and mediolateral shear at all tested speeds. Asymmetrical loading persists in individuals with unilateral transfemoral amputation during double limb stance. Increasing walking speed increased ground reaction force loading asymmetries, which may make individuals with unilateral transfemoral amputation more susceptible to knee osteoarthritis or other musculoskeletal disorders. Further study is necessary to develop ideal gait strategies for the minimization of gait asymmetry in individuals with unilateral transfemoral amputation.

Identification and exploration of the GRF and GIF families in maize and foxtail millet

Plant growth and development are dependent on complex regulatory networks to adapt various environments. The growth regulatory factor (GRF) and GRF-interacting factor (GIF) families have been shown to control growth in various plant species. There are growing evidences that GRFs and GIFs can improve crop genetic transformation efficiency. In this study, we identified and classified 17 ZmGRFs, 10 SiGRFs, 4 ZmGIFs and 3 SiGIFs in maize (Zea mays L.) and foxtail millet (Setaria italica L.) using updated genome data. Many ABREs (Abscisic Acid-responsive elements) were present in the promoter regions of GRFs by analysis, and the expression levels of ZmGRF4, 9, 12, 14 and ZmGIF2 were associated with the Abscisic Acid (ABA) response. Furthermore, ZmGRF9 showed collinearity with AtGRF5 between Arabidopsis and maize. ZmGRF9 conservatively interacts with ZmGIF 2, 3, and 4. As a result, we systematically identified GRF and GIF family members, analyzed the regulatory network, and found that exogenous ABA inhibited the expression of GRFs, regulating responses to stress in the environment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01234-z.

Genome-wide analysis of the G-box regulating factors protein family reveals its roles in response to Sclerotinia sclerotiorum infection in rapeseed (Brassica napus L.)

The G-box regulating factors (GRFs) are involved in a wide array of signal transduction pathway and play important roles in plant physiological and developmental processes and stress responses. The GRF proteins have previously been described in several plant species, but not in rapeseed (Brassica napus L.). In this study, we carried out genome-wide analysis of GRFs in B. napus based on the available genome sequence information, and analyzed their expression in different tissues under different hormone treatments and after inoculation with Sclerotinia sclerotiorum. We identified 46 putative BnaGRF genes in rapeseed, unevenly distributed on 18 chromosomes. Like the 14-3-3 proteins in other plant species, the 46 putative BnaGRFs could be classified into two major evolutionary branches: epsilon (ε) group and non-epsilon (non-ε) group. Evolutionary analysis indicated that the BnaGRF gene family expanded in both groups much before speciation. We discovered an expansion of the 14-3-3 gene family that likely occurred during a recent gene duplication event. Collinearity analysis revealed that most of the BnaGRF genes shared syntenic relationships. Global gene expression profiling of BnaGRFs by RNA-seq analysis showed 41.3% (19/46) response to S. sclerotiorum infection, and this response was probably mediated through jasmonic acid (JA) and salicylic acid (SA) signaling pathways. These results provide key insights into the role of 14-3-3s in the biotic stress response and enhance our understanding of their multiple functions in B. napus.

The relationship between bowling intensity and ground reaction force in cricket pace bowlers

This study examined the relationship between perceived bowling intensity, ball release speed and ground reaction force (measured by peak force, impulse and loading rate) in male pace bowlers. Twenty participants each bowled 36 deliveries, split evenly across three perceived intensity zones: low = 70% of maximum perceived bowling effort, medium = 85%, and high = 100%. Peak force and loading rate were significantly different across the three perceived intensity zones in the horizontal and vertical directions (Cohen's d range = 0.14-0.45, p < 0.01). When ball release speed increased, peak force and loading rate also increased in the horizontal and vertical directions (η_p² = 0.04-0.18, p < 0.01). Lastly, bowling at submaximal intensities (i.e., low - medium) was associated with larger decreases in peak horizontal force (7.9-12.3% decrease), impulse (15.8-21.4%) and loading rate (7.4-12.7%) compared to decreases in ball release speed (5.4-8.3%). This may have implications for bowling strategies implemented during training and matches, particularly for preserving energy and reducing injury risk.

Factor analysis of the biomechanical parameters of pole vault run-up and takeoff: exploring sports performance

This study aimed to explore a parameter system and build a linear prediction model to effectively and comprehensively evaluate pole vault performance. The Qualisys motion capture system (200 Hz) and three Kistler force platforms (2000 Hz) were used to collect the athletes' kinematics and ground reaction force data of run-up and takeoff. Finally, 26 biomechanical parameters of 30 successful vaults of eight athletes were analysed by factor analysis, and linear regression analysis was conducted on the extracted factors. Three factors were extracted by factor analysis: F1, F2, and F3. The mean maximum COM height of the 30 vaults was 4.974 m. The score of F2 and F1 increased by 1, and the maximum COM height increased by 0.131 m and 0.112 m, respectively. The F3 did not participate in the prediction of performance. For the training of coaches and athletes, athletes of a higher stature need to expend more effort to achieve a higher training level. Furthermore, improving the speed, mechanical energy, and horizontal propulsion GRF of run-up and takeoff, as well as optimising the force generation strategy of the three lower limb joints in the takeoff support phase, help to achieve a good pole vault performance.

Discriminating features of ground reaction forces in overweight old and young adults during walking using functional principal component analysis

BACKGROUND

Limited attention has been paid to age- or body size-related changes in the ground reaction forces (GRF) during walking despite their strong associations with lower limb injuries and pathology.

RESEARCH QUESTION

Do the features of GRF during walking associate with age or body size?

METHODS

Fifty-four participants were subdivided into four groups according to their age and body size: overweight old (n = 12), non-overweight old (n = 13), overweight young (n = 13), and non-overweight young (n = 16). Participants were asked to walk at their self-selected speeds on level ground with force plates embedded in the center of walkway. Functional principal component analysis (FPCA) was performed to extract major modes of variation and functional principal component scores (FPCs) in three-dimensional GRFs. Analysis of variance models were employed to investigate the effect of age, body size, or their interactions on the FPCs of each component of the GRF, with the adjustment to gait speed.

RESULTS

Significant age and body size effects were observed in FPC1 across all three-dimensional GRF. Both overweight and older groups showed greater braking force after heel-strike and greater propulsive forces during pre-swing when compared to the non-overweight and younger groups, respectively. The overweight old group displayed greater medial forces during mid-stance and the overweight young group showed prominently larger medial forces during pre-swing, while non-overweight old showed a tendency of flatter medial-lateral GRF waveforms during the entire stance phase. FPC2 revealed that only body size had an effect on three-dimensional GRF with the highest FPC2 scores in the overweight old group.

SIGNIFICANCE

Three-dimensional GRF during walking could be altered by the body size and age, which were more pronounced in the overweight and older group. The more dynamic GRF pattern with greater and/or lower peaks could be contributing factors to the increased joint load and injury rates observed in overweight aged individuals.

Predicting continuous ground reaction forces from accelerometers during uphill and downhill running: a recurrent neural network solution

BACKGROUND

Ground reaction forces (GRFs) are important for understanding human movement, but their measurement is generally limited to a laboratory environment. Previous studies have used neural networks to predict GRF waveforms during running from wearable device data, but these predictions are limited to the stance phase of level-ground running. A method of predicting the normal (perpendicular to running surface) GRF waveform using wearable devices across a range of running speeds and slopes could allow researchers and clinicians to predict kinetic and kinematic variables outside the laboratory environment.

PURPOSE

We sought to develop a recurrent neural network capable of predicting continuous normal (perpendicular to surface) GRFs across a range of running speeds and slopes from accelerometer data.

METHODS

Nineteen subjects ran on a force-measuring treadmill at five slopes (0°, ±5°, ±10°) and three speeds (2.5, 3.33, 4.17 m/s) per slope with sacral- and shoe-mounted accelerometers. We then trained a recurrent neural network to predict normal GRF waveforms frame-by-frame. The predicted versus measured GRF waveforms had an average ± SD RMSE of 0.16 ± 0.04 BW and relative RMSE of 6.4 ± 1.5% across all conditions and subjects.

RESULTS

The recurrent neural network predicted continuous normal GRF waveforms across a range of running speeds and slopes with greater accuracy than neural networks implemented in previous studies. This approach may facilitate predictions of biomechanical variables outside the laboratory in near real-time and improves the accuracy of quantifying and monitoring external forces experienced by the body when running.

Highly efficient, genotype-independent transformation and gene editing in watermelon (Citrullus lanatus) using a chimeric ClGRF4-GIF1 gene

Efficient genetic transformation has the potential to advance research and breeding in watermelon (Citrullus lanatus), but regeneration from tissue culture remains challenging. Previous work showed that expressing a fusion of two interacting transcription factors, GROWTH-REGULATING FACTOR4 (GRF4) and GRF-INTERACTING FACTOR1 (GIF1), improved regeneration in wheat (Triticum aestivum). By overexpressing a chimeric fusion of ClGRF4 and ClGIF1, we achieved highly efficient transformation in watermelon. Mutating the mi396 microRNA target site in ClGRF further boosted the transformation efficiency up to 67.27% in a genotype-independent manner. ClGRF4-GIF1 can also be combined with clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome editing tools to achieve highly efficient gene editing in watermelon, which we used to successfully create diploid seedless watermelon. This research thus puts forward a powerful transformation tool for future watermelon research and breeding.

Single-Leg Drop Jump Biomechanics After Ankle or Knee Joint Cooling in Healthy Young Adults

CONTEXT

It is unclear if lower-extremity joint cooling alters biomechanics during a functional movement.

OBJECTIVE

To investigate the effects of unilateral lower-extremity cryotherapy on movement alterations during a single-leg drop jump.

DESIGN

A crossover design.

SETTING

Laboratory.

PATIENTS

Twenty healthy subjects (10 males and 10 females; 23 y, 169 cm, 66 kg).

INTERVENTION(S)

Subjects completed a single-leg drop jump before and after a 20-minute ankle or knee joint cooling on the right leg, or control (seated without cooling) on 3 separate days.

MAIN OUTCOME MEASURES

Time to peak knee flexion, vertical ground reaction force, lower-extremity joint angular velocity (sagittal plane only), and angle and moment (sagittal and frontal planes) in the involved leg over the entire ground contact (GC; from initial contact to jump-off) during the first landing. Time to peak knee flexion was compared using an analysis of variance; the rest of the outcome measures were analyzed using functional analyses of variance (P < .05).

RESULTS

Neither joint cooling condition changed the time to peak knee flexion (F2,95 = 0.73, P = .49). Ankle joint cooling reduced vertical ground reaction force (55 N at 4% of GC), knee joint angular velocity (44°/s during 5%-9% of GC), and knee varus moment (181 N·m during 18%-20% of GC). Knee joint cooling resulted in a reduction in knee joint angular velocity (24°/s during 37%-40% of GC) and hip adduction moment (151 N·m during 46%-48% of GC), and an increase in hip joint angular velocity (16°/s during 49%-53% of GC) and plantarflexion angle (1.5° during 11%-29% of GC).

CONCLUSION

Resuming activity immediately after lower-extremity joint cooling does not seem to predispose an individual to injury during landing because altered mechanics are neither overlapping with the injury time period nor of sufficient magnitude to lead to an injury.

Results of a 5-Year N-of-1 Growth Hormone Releasing Hormone Gene Therapy Experiment

Here presented for the first time are results showing persistence over a 5+ year period in a human who had a hormone gene therapy administered to muscle. This growth hormone releasing hormone (GHRH) therapy was administered in two doses, a year apart, with a mean after the second dose of 195 ng/mL (13 × normal, σ = 143, σ_M = 34, max = 495, min = 53). This level of GHRH therapy appears to be safe for the subject, although there were some adverse events. Insulin-like growth factor 1 levels were little affected, nor were the growth hormone test results, showing no indications of acromegaly for the hormone homologue used. Heart rate declined 8 to 13 bpm, persistent over 5 years. Testosterone rose by 52% (σ = 22%, σ_M = 6%). The high-density lipoprotein/low-density lipoprotein ratio dropped from 3.61 to mean 2.81 (σ = 0.26, σ_M = 0.057, max = 3.3, min = 2.5), and triglycerides declined from 196 mg/dL to mean 94.4 mg/dL (σ = 21.9, σ_M = 5.0, min = 59, max = 133, min = 59). White blood cell counts increased, however, the baseline was not strong. CD4 and CD8 mean increased by11.7% (σ = 11.6%, σ_M = 3.3%, max = 30.7%, min = -9.6%) and 12.0% (σ = 10.5%, σ_M = 3.0%, max = 29.1%, min = -6.7%), respectively. Ancillary observations comprise an early period of euphoria, and a dramatic improvement in visual correction after the first dose, spherical correction from baseline (L/R) -2.25/-2.75 to -0.25/-0.5. Over the next 5 years, correction drifted back to -1.25/-1.75. Horvath PhenoAge was cut 44.1% post-treatment. At completion, epigenetic age was -6 years (-9.3%), and telomere age was +7 months (+0.9%).

Alleles of the GRF3-2A Gene in Wheat and Their Agronomic Value

The Growth-regulating factors (GRF) are a family of plant-specific transcription factors that have roles in plant growth, development and stress response. In this study the diversity of the TaGRF3-2A (TraesCS2A02G435100) gene was investigated in Russian bread wheat germplasm by means of next generation sequencing and molecular markers, and the results compared with those from multiple wheat genome and exome sequencing projects. The results showed that an allele possessing c.495G>T polymorphism found in Bezostaya 1 and designated as TaGRF3-2Ab, is connected with earlier heading and better grain filling under conditions of the Krasnodar Krai. TaGRF3-2Ab is more frequent among Russian winter wheat cultivars than in other germplasms found in the world, implying that it is adaptive for the Chernozem region. A new rare mutation of the TaGRF3-2A was found in the spring wheat cultivar Novosibirskaya 67. The molecular markers developed will facilitate utilization of TaGRF3-2A mutations in future agronomic studies and wheat improvement. Albeit GRF3-2Ab may be good at maintaining high milling quality of the grain, it should be used with caution in breeding of winter wheat cultivars in the perspective of climate change.

glandulosa

Growth-regulating factors (GRFs) are important regulators of plant development and growth, but their possible roles in xylem development in woody plants remain unclear. Here, we report that Populus alba × Papulus glandulosa PagGRF12a negatively regulates xylem development in poplar. PagGRF12a is expressed in vascular tissues. Compared to non-transgenic control plants, transgenic poplar plants overexpressing PagGRF12a exhibited reduced xylem width and plants with repressed expression of PagGRF12a exhibited increased xylem width. Xylem NAC domain 1 (XND1) encodes a NAC domain transcription factor that regulates xylem development and transcriptional analyses revealed that PagXND1a is highly upregulated in PagGRF12a-overexpressing plants and downregulated in PagGRF12a-suppressed plants, indicating that PagGRF12a may regulate xylem development through PagXND1a. Transient transcriptional assays and chromatin immunoprecipitation-polymerase chain reaction assays confirmed that PagGRF12a directly upregulates PagXND1a. In addition, PagGRF12a interacts with the GRF-Interacting Factor (GIF) PagGIF1b, and this interaction enhances the effects of PagGRF12a on PagXND1a. Our results indicate that PagGRF12a inhibits xylem development by upregulating the expression of PagXND1a.

Genome-Wide Identification and Characterization of the Abiotic-Stress-Responsive GRF Gene Family in Diploid Woodland Strawberry (Fragaria vesca)

Growth regulatory factors (GRF) are plant-specific transcription factors that play an important role in plant resistance to stress. This gene family in strawberry has not been investigated previously. In this study, 10 GRF genes were identified in the genome of the diploid woodland strawberry (Fragaria vesca). Chromosome analysis showed that the 10 FvGRF genes were unevenly distributed on five chromosomes. Phylogenetic analysis resolved the FvGRF proteins into five groups. Genes of similar structure were placed in the same group, which was indicative of functional redundance. Whole-genome duplication/segmental duplication and dispersed duplication events effectively promoted expansion of the strawberry GRF gene family. Quantitative reverse transcription-PCR analysis suggested that FvGRF genes played potential roles in the growth and development of vegetative organs. Expression profile analysis revealed that FvGRF3, FvGRF5, and FvGRF7 were up-regulated under low-temperature stress, FvGRF4 and FvGRF9 were up-regulated under high-temperature stress, FvGRF6 and FvGRF8 were up-regulated under drought stress, FvGRF3, FvGRF6, and FvGRF8 were up-regulated under salt stress, FvGRF2, FvGRF7, and FvGRF9 were up-regulated under salicylic acid treatment, and FvGRF3, FvGRF7, FvGRF9, and FvGRF10 were up-regulated under abscisic acid treatment. Promoter analysis indicated that FvGRF genes were involved in plant growth and development and stress response. These results provide a theoretical and empirical foundation for the elucidation of the mechanisms of abiotic stress responses in strawberry.

MiR396-GRF module associates with switchgrass biomass yield and feedstock quality

Improving plant biomass yield and/or feedstock quality for highly efficient lignocellulose conversion has been the main research focus in genetic modification of switchgrass (Panicum virgatum L.), a dedicated model plant for biofuel production. Here, we proved that overexpression of miR396 (OE-miR396) leads to reduced plant height and lignin content mainly by reducing G-lignin monomer content. We identified nineteen PvGRFs in switchgrass and proved thirteen of them were cleaved by miR396. MiR396-targeted PvGRF1, PvGRF9 and PvGRF3 showed significantly higher expression in stem. By separately overexpressing rPvGRF1, 3 and 9, in which synonymous mutations abolished the miR396 target sites, and suppression of PvGRF1/3/9 activity via PvGRF1/3/9-SRDX overexpression in switchgrass, we confirmed PvGRF1 and PvGRF9 played positive roles in improving plant height and G-lignin content. Overexpression of PvGRF9 was sufficient to complement the defective phenotype of OE-miR396 plants. MiR396-PvGRF9 modulates these traits partly by interfering GA and auxin biosynthesis and signalling transduction and cell wall lignin, glucose and xylan biosynthesis pathways. Moreover, by enzymatic hydrolysis analyses, we found that overexpression of rPvGRF9 significantly enhanced per plant sugar yield. Our results suggest that PvGRF9 can be utilized as a candidate molecular tool in modifying plant biomass yield and feedstock quality.

Waveform analysis of shank loaded wearable resistance during sprint running acceleration

Lower-limb wearable resistance (WR) provides a specific and targeted overload to the musculature involved in sprint running, however, it is unknown if greater impact forces occur with the additional limb mass. This study compared the contact times and ground reaction force waveforms between sprint running with no load and 2% body mass (BM) shank-positioned WR over 30 m. Fifteen male university-level sprint specialists completed two maximum effort sprints with each condition in a randomized order. Sprint running with shank WR resulted in trivial changes to contact times at 5 m, 10 m, and 20 m (effect size [ES] = <0.20, p > 0.05) and a small, significant increase to contact time at 30 m by 1.94% (ES = 0.25, p = 0.03). Significant differences in ground reaction force between unloaded and shank loaded sprint running were limited to the anterior-posterior direction and occurred between 20% and 30% of ground contact at 10 m, 20 m, and 30 m. Shank WR did not result in greater magnitudes of horizontal or vertical forces during the initial impact portion of ground contact. Practitioners can prescribe shank WR training with loads ≤2% BM without concern for increased risk of injurious impact forces.

Delayed Graft Reposition on Flap (GRF) in Six Week Old Allen Type 4 Amputation: Case Report

An exceptional case like our patient who was a 24-year-old man presented 6 weeks after type 4 Allen amputation to his right index finger where primary surgical stump closure was done, presented to us with the amputated distal part warm preserved. The reposition of distal amputated part using the authors described GRF (Graft Reposition on Flap) technique was done and followed. Good consolidation and bone graft union, good nail with near normal pulp and normal sensation with good functional outcome was achieved at the one-year final follow up.

Are the Kinetics and Kinematics of the Surf Pop-Up Related to the Anthropometric Characteristics of the Surfer?

The surf pop-up is a unique and challenging skill, critical to successful surfing. Hypothesizing that anthropometric characteristics of surfers influence the pop-up performance, we aimed to measure kinematics and ground-reaction forces (GRF) during a simulated pop-up motion, and to relate these variables with anthropometric characteristics. Twenty-three male surfers (age: 28.4 ± 10.1 years old; body mass: 68.3 ± 10.8 kg; height: 1.73 ± 0.07 m; time of practice: 12.4 ± 8.9 years; arm-span: 1.75 ± 8.9 m) perform a simulated pop-up in the laboratory, while GRF and 3D motion-capture data were acquired. The duration of the pop-up was 1.20 ± 0.19 s (60% push-up and 40% reaching/landing phase). During the push-up, the hands were placed 0.46 ± 0.05 m apart and generated a relative total peak-force of 0.99 ± 0.10 N/Weight, with symmetrical impulse of 0.30 ± 0.05 N·s/Weight for the dominant and 0.29 ± 0.07 N·s/Weight for the nondominant hand. Elbow angles were not different during the peak force application (110 ± 18° vs. 112 ± 18°, respectively) of the push-up phase. During the landing phase, the feet were placed 0.63 ± 0.10 m apart and generated a relative peak force of 1.63 ± 0.18 N/Weight. The impact force during landing was applied unevenly between the rear foot (28%) and the front foot (72%). In conclusion, most anthropometric-related variables showed no relationship with performance variables, with the exception of an inverse relationship between muscle mass and pop-up total duration. We also observed no differences in upper- and lower-body kinematics between the dominant vs. nondominant hands and among surfers who preferred a regular vs. “goofy-foot” stance. Finally, the force profiles between hands were similar and symmetric, while the lower extremities during the reaching phase were different, with the front foot applying greater force than that of the rear foot.

Genome-wide analysis of growth-regulating factors (GRFs) in Triticum aestivum

The Growth-Regulating Factor (GRF) family encodes a type of plant-specific transcription factor (TF). GRF members play vital roles in plant development and stress response. Although GRF family genes have been investigated in a variety of plants, they remain largely unstudied in bread wheat (Triticum aestivum L.). The present study was conducted to comprehensively identify and characterize the T. aestivum GRF (TaGRF) gene family members. We identified 30 TaGRF genes, which were divided into four groups based on phylogenetic relationship. TaGRF members within the same subgroup shared similar motif composition and gene structure. Synteny analysis suggested that duplication was the dominant reason for family member expansion. Expression pattern profiling showed that most TaGRF genes were highly expressed in growing tissues, including shoot tip meristems, stigmas and ovaries, suggesting their key roles in wheat growth and development. Further qRT-PCR analysis revealed that all 14 tested TaGRFs were significantly differentially expressed in responding to drought or salt stresses, implying their additional involvement in stress tolerance of wheat. Our research lays a foundation for functional determination of TaGRFs, and will help to promote further scrutiny of their regulatory network in wheat development and stress response.

The Rice miR396-GRF-GIF-SWI/SNF Module: A Player in GA Signaling

Rice Growth-Regulating Factors (GRFs) were originally identified to be gibberellin (GA)-induced, but the nature of GA induction has remained unknown because most reports thereafter focused on revealing their roles in growth-promoting activities. GRFs have the WRC (Trp, Arg, Cys) domain to target DNA and contain the QLQ (Gln, Leu, Gln) domain to interact with GRF-Interacting Factor (GIF), which recruits ATP-dependent DNA translocase Switch/Sucrose Non-fermenting (SWI/SNF) for chromatin remodeling. Both GRFs and GIFs exhibit transcriptional activities but GIFs lack a DNA-binding domain. So, GRFs act like a navigator in the GRF-GIF-SWI/SNF complex, determining when and where the complex should work on. The levels of most rice GRFs can be sensitively regulated by miR396, which responds to many developmental and environmental factors. Recent clues from several studies highlight the original question of how GRFs participate in GA signaling. DELLA (contain DELLA motif) protein plays dual roles in controlling the level of GRFs by regulating the level of miR396 and interacting with GRFs. Here we address the question of why this complex plays an essential role in controlling plant growth focusing on the action of GA signaling pivot, DELLA.

Tightly controlled expression of OsbHLH35 is critical for anther development in rice

Anther development is a complex process regulated by a myriad of transcription factors belonging to distinct protein families. In this study, we focus on the functional characterization of OsbHLH35, a basic Helix-Loop-Helix (bHLH) TF that regulates anther development in rice. Plants overexpressing OsbHLH35 presented small and curved anthers, leading to a reduction of 72 % on seed production. Rice transgenic plants expressing GUS reporter gene under the control of OsbHLH35 promoter (pOsbHLH35::GUS) showed that this TF specifically accumulates in anthers at the meiosis stage and in other spikelet tissues. Yeast one-hybrid screening identified three members of the Growth-Regulating Factor (GRF) family, OsGRF3, OsGRF4, and OsGRF11, as transcriptional regulators of OsbHLH35. Transactivation assay showed that OsGRF11 negatively regulates OsbHLH35 expression in Arabidopsis protoplasts. This regulation was also observed in planta through the analysis of transgenic plants overexpressing OsGRF11 (OsGRF11OE), confirming that OsGRF11 is a negative regulator of OsbHLH35 in rice. Our data suggest that OsbHLH35 plays an essential role in anther development in rice and the fine control of its expression is crucial to ensure proper seed production.

Comparison of the Turn Switch Time Points Measured by Portable Force Platforms and Pressure Insoles

Several methods to determine turn switch points during alpine skiing using the vertical GRF exist in the literature. Although comparative studies between pressure insoles (PI) and force platforms (FP) have been conducted, there are no reports comparing the detected time points. Yet, these sensors and methods have been used interchangeably. This study aims to compare the turn switch time points with both sensors and various methods. Twenty skiers performed turns with FP and PI for two different ski styles (high and low dynamic turns). Three different assessment methodologies were compared: minima, functional minima, and crossings. Bland Altman and repeated measures ANOVA were used to assess statistical differences. Main effects of sensor and method were observed (p < 0.001). Although there was a low effect size (ηp2 = 0.013) between FP and PI, the 95% CI yielded values representing >30% of the turn duration. A large effect size (η² = 0.153) was found between the crossing method and the minima and functional minima methods. This indicates that those methods assess different events during the turn switch phase. In conclusion, the sensors and assessment methodologies compared in this study are not interchangeable with the possible exception of the minima and functional minima assessed with FP.

Genome-Wide Identification and Molecular Characterization of the Growth-Regulating Factors-Interacting Factor Gene Family in Tomato

Growth-regulating factors-interacting factor (GIF) proteins play crucial roles in the regulation of plant growth and development. However, the molecular mechanism of GIF proteins in tomato is poorly understood. Here, four SlGIF genes (named SlGRF1a, SlGIF1b, SlGIF2, and SlGIF3) were identified from the tomato genome and clustered into two major clades by phylogenetic analysis. The gene structure and motif pattern analyses showed similar exon/intron patterns and motif organizations in all the SlGIFs. We identified 33 cis-acting regulatory elements (CAREs) in the promoter regions of the SlGIFs. The expression profiling revealed the four GIFs are expressed in various tissues and stages of fruit development and induced by phytohormones (IAA and GA). The subcellular localization assays showed all four GIFs were located in nucleus. The yeast two-hybrid assay indicated various growth-regulating factors (SlGRFs) proteins interacted with the four SlGIF proteins. However, SlGRF4 was a common interactor with the SlGIF proteins. Moreover, a higher co-expression relationship was shown between three SlGIF genes and five SlGRF genes. The protein association network analysis found a chromodomain helicase DNA-binding protein (CHD) and an actin-like protein to be associated with the four SlGIF proteins. Overall, these results will improve our understanding of the potential functions of GIF genes and act as a base for further functional studies on GIFs in tomato growth and development.

An autoinhibitory role for the GRF zinc finger domain of DNA glycosylase NEIL3

The NEIL3 DNA glycosylase maintains genome integrity during replication by excising oxidized bases from single-stranded DNA (ssDNA) and unhooking interstrand cross-links (ICLs) at fork structures. In addition to its N-terminal catalytic glycosylase domain, NEIL3 contains two tandem C-terminal GRF-type zinc fingers that are absent in the other NEIL paralogs. ssDNA binding by the GRF-ZF motifs helps recruit NEIL3 to replication forks converged at an ICL, but the nature of DNA binding and the effect of the GRF-ZF domain on catalysis of base excision and ICL unhooking is unknown. Here, we show that the tandem GRF-ZFs of NEIL3 provide affinity and specificity for DNA that is greater than each individual motif alone. The crystal structure of the GRF domain shows that the tandem ZF motifs adopt a flexible head-to-tail configuration well-suited for binding to multiple ssDNA conformations. Functionally, we establish that the NEIL3 GRF domain inhibits glycosylase activity against monoadducts and ICLs. This autoinhibitory activity contrasts GRF-ZF domains of other DNA-processing enzymes, which typically use ssDNA binding to enhance catalytic activity, and suggests that the C-terminal region of NEIL3 is involved in both DNA damage recruitment and enzymatic regulation.

Improvement in sprint start performance by modulating an initial loading location on the starting blocks

This study examined whether modulation of the centre of pressure (COP) on the starting block surface would improve sprint start performance. Twenty male national-level sprinters performed 15-m sprints from the starting blocks in three different conditions (normal, anterior loading and posterior loading), during which ground reaction forces (GRFs) were recorded. The COP location, 10-m time, average horizontal external power (AHEP), spatiotemporal and GRF variables were calculated. The results demonstrate that, although modulation of COP location may not improve sprint start performance for the entire group, it could improve the corresponding performance for specific individuals. A sprinter who favours the posterior front block location and more to the posterior rear block COP location on the block surface at the set position could possibly improve AHEP using the anterior loading condition. An improvement of AHEP in the anterior loading condition (p =.056, effect size [ES] =.305) would be accomplished by greater rear block anteroposterior mean force (p =.043, ES =.574). Moreover, the posterior loading condition may improve the 10-m time and/or AHEP for some individuals, whereas no specific characteristics of the individuals were found. Finally, an improvement of 10-m time in the posterior loading condition (p =.015, ES =.609) would be accomplished by shorter reaction time (p =.035, ES =.780).

Does ground-reaction force influence post-impact ball speed in the tennis forehand groundstroke?

Motion of the rear leg during a tennis forehand was previously reported to influence the ball speed. However, impact of a kinetic measure such as the ground-reaction force (GRF) on forehand ball speed has not been investigated. The aim of this study was to investigate the influence of GRF on forehand ball speed and identify the most influential component of GRF related to overall higher ball speeds. Nine tennis players (eight males, one female) were invited to participate. Three testing sessions were conducted. Each session consisted of maximal forehand ball-speed testing and seven forehands at three ball speeds; fast (100%), medium (90%) and slow (80%). GRF and post-impact ball speed were measured for each stroke. Of all the individual GRF vectors, peak anterior-posterior force best explained the changes in ball speed, where 26% (R² = 0.26) of ball speed variance can be explained by this force vector alone. In a stepwise fashion, adding peak lateral force to the model explained a further 7% (R² = 0.33). Combining peak anterior-posterior, medial-lateral and vertical forces explained a total of 37% (R² = 0.37). Peak anterior-posterior force appears to be the most influential ground-reaction force affecting forehand post-impact ball speed.

ORESARA15 Acts Synergistically with ANGUSTIFOLIA3 and Separately from AINTEGUMENTA to Promote Cell Proliferation during Leaf Growth

Developing leaves undergo sequential coordinated cell proliferation and cell expansion to determine their final size and shape. Although several important regulators of cell proliferation have been reported, the gene network regulating leaf developmental processes remains unclear. Previously, we showed that ORESARA15 (ORE15) positively regulates the rate and duration of cell proliferation by promoting the expression of direct targets, GROWTH-REGULATING FACTOR (GRF) transcription factors, during leaf growth. In the current study, we examined the spatiotemporal patterns of ORE15 expression and determined that ORE15 expression partially overlapped with AN3/GIF1 and ANT expression along the midvein in the proximal region of the leaf blade in young leaves. Genetic analysis revealed that ORE15 may function synergistically with AN3 to control leaf growth as a positive regulator of cell proliferation. Our molecular and genetic studies are the first to suggest the importance of functional redundancies between ORE15 and AN3, and between AN3 and ANT in cell proliferation regulatory pathway during leaf growth.

Increased gait variability during robot-assisted walking is accompanied by increased sensorimotor brain activity in healthy people

BACKGROUND

Gait disorders are major symptoms of neurological diseases affecting the quality of life. Interventions that restore walking and allow patients to maintain safe and independent mobility are essential. Robot-assisted gait training (RAGT) proved to be a promising treatment for restoring and improving the ability to walk. Due to heterogenuous study designs and fragmentary knowlegde about the neural correlates associated with RAGT and the relation to motor recovery, guidelines for an individually optimized therapy can hardly be derived. To optimize robotic rehabilitation, it is crucial to understand how robotic assistance affect locomotor control and its underlying brain activity. Thus, this study aimed to investigate the effects of robotic assistance (RA) during treadmill walking (TW) on cortical activity and the relationship between RA-related changes of cortical activity and biomechanical gait characteristics.

METHODS

Twelve healthy, right-handed volunteers (9 females; M = 25 ± 4 years) performed unassisted walking (UAW) and robot-assisted walking (RAW) trials on a treadmill, at 2.8 km/h, in a randomized, within-subject design. Ground reaction forces (GRFs) provided information regarding the individual gait patterns, while brain activity was examined by measuring cerebral hemodynamic changes in brain regions associated with the cortical locomotor network, including the sensorimotor cortex (SMC), premotor cortex (PMC) and supplementary motor area (SMA), using functional near-infrared spectroscopy (fNIRS).

RESULTS

A statistically significant increase in brain activity was observed in the SMC compared with the PMC and SMA (p < 0.05), and a classical double bump in the vertical GRF was observed during both UAW and RAW throughout the stance phase. However, intraindividual gait variability increased significantly with RA and was correlated with increased brain activity in the SMC (p = 0.05; r = 0.57).

CONCLUSIONS

On the one hand, robotic guidance could generate sensory feedback that promotes active participation, leading to increased gait variability and somatosensory brain activity. On the other hand, changes in brain activity and biomechanical gait characteristics may also be due to the sensory feedback of the robot, which disrupts the cortical network of automated walking in healthy individuals. More comprehensive neurophysiological studies both in laboratory and in clinical settings are necessary to investigate the entire brain network associated with RAW.

The Location of the Center of Pressure on the Starting Block Is Related to Sprint Start Performance

Force application locations [i.e., center of pressure (COP)] on the block surface are not necessarily the same for individuals even if the same block locations and angles are used. The purpose of this study was to examine the association of block clearance performance with COP location on the starting block surface. Twenty-one male sprinters performed 60 m sprints from the starting blocks, during which the ground reaction forces (GRFs) on the starting blocks were recorded using two force platforms. Using a previously validated method, changes in COP location on the block surface during the block clearance for each block was calculated from the marker coordinates on the block surface, GRF signals, and moment data around the center of the force platform at the ground level. Moreover, average horizontal external power (AHEP), which was considered the key performance criterion, was computed. Statistical parametric mapping (SPM) 1D linear regressions were used to test relationships between AHEP and COP location curves in the anteroposterior and vertical directions. The COP for both legs moved backward and upward (0.042 and 0.042 m for the front block and 0.030 and 0.034 m for the rear block) at first and then forward and downward (0.113 and 0.094 m for the front block and 0.095 and 0.087 m for the rear block) toward the toe-off. Based on SPM results, AHEP was correlated with front block anteroposterior and vertical COP locations from 12.9 to 20.8% and from 10.4 to 22.2% of the force production phase, respectively, while it was correlated with rear block vertical COP location from 31.9 to 37.4% of the force production phase. In conclusion, the current results demonstrate that, regardless of the starting block location and angle, better sprint start performance is accomplished with a higher and more to the rear COP on the starting block surface, when COP is located close to heel during the middle phase of the block clearance. The fact that the COP location is related to sprint start performance will be useful for sprinters and coaches who intend to improve sprint start performance.

Genome-Wide Analysis of the Growth-Regulating Factor Family in Peanut (Arachis hypogaea L.)

Growth-regulating factors (GRFs) are plant-specific transcription factors that perform important functions in plant growth and development. Herein, we identified and characterised 24 AhGRF genes in peanut (Arachis hypogaea). AhGRF family genes were divided into six classes with OLQ and WRC domains. Transcriptome expression profile showed that more AhGRF genes, such as AhGRF5a gene, were at higher expression during pod development in Arachis monticola than cultivated species, especially at the pod rapid-expansion stage. AhGRF5a and AhGRF5b genes expressed at higher levels in pods than roots, leaves and stems tissues, existing in the difference between Arachis monticola and H8107. Exogenous GA3 application can activate AhGRF5a and AhGRF5b genes and H8107 line showed more positive response than Arachis monticola species. These results imply that these two AhGRF genes may be active during the peanut pod development.

An actuated dissipative spring-mass walking model: Predicting human-like ground reaction forces and the effects of model parameters

Simple models are widely used to understand the mechanics of human walking. The optimization-based minimal biped model and spring-loaded-inverted-pendulum (SLIP) model are two popular models that can achieve human-like walking patterns. However, ground reaction forces (GRF) from these two models still deviate from experimental data. In this paper, we proposed an actuated dissipative spring-mass model by integrating these two models to realize more human-like GRF patterns. We first explored the function of stiffness, damping, and weights of both energy cost and force cost in the objective function and found that these parameters have distinctly different influences on the optimized gait and GRF profiles. The stiffness and objective weight affect the number and size of peaks in the vertical GRF and stance time. The damping changes the relative size of the peaks but has little influence on stance time. Based on these observations, these parameters were manually tuned at three different speeds to approach experimentally measured vertical GRF and the highest correlation coefficient can reach 0.983. These results indicate that the stiffness, damping, and proper objective functions are all important factors in achieving human-like motion for this simple walking model. These findings can facilitate the understanding of human walking dynamics and may be applied in future biped models.

Comparison of 2 Forms of Kinetic Biofeedback on the Immediate Correction of Knee Extensor Moment Asymmetry Following Total Knee Arthroplasty During Decline Walking

BACKGROUND

Individuals with total knee arthroplasty (TKA) display interlimb knee extensor moment (KEM) asymmetry during level walking that is exacerbated as task demands are increased. Studies using biofeedback to correct interlimb KEM asymmetry following TKA have reported mixed results.

OBJECTIVE

To compare the immediate effect of 2 forms of real-time kinetic biofeedback-vertical ground reaction force (vGRF) or KEM-on improving interlimb peak KEM symmetry during the weight-acceptance phase of decline walking in persons who have undergone TKA.

METHODS

In this cross-sectional, controlled laboratory study, 30 participants (17 men; mean ± SD age, 61.9 ± 8.5 years; body mass index, 28.4 ± 3.7 kg/m²) were allocated to either a vGRF or KEM real-time biofeedback group. Peak KEM interlimb asymmetry was obtained during both nonbiofeedback and biofeedback decline walking trials 3 months following TKA.

RESULTS

Significant interlimb asymmetry in peak KEM was observed in both groups during the nonbiofeedback condition (KEM, P = .02; vGRF, P<.01). The KEM biofeedback group demonstrated an immediate improvement in peak KEM asymmetry (P = .42). No change in peak KEM asymmetry was observed in the vGRF biofeedback group (P = .01).

CONCLUSION

Knee extensor moment biofeedback has an immediate effect on improving peak KEM asymmetry 3 months post TKA. J Orthop Sports Phys Ther 2019;49(2):105-111. Epub 20 Aug 2018. doi:10.2519/jospt.2019.7800.

Estimation of Tri-Axial Walking Ground Reaction Forces of Left and Right Foot from Total Forces in Real-Life Environments

Continuous monitoring of natural human gait in real-life environments is essential in many applications including disease monitoring, rehabilitation, and professional sports. Wearable inertial measurement units are successfully used to measure body kinematics in real-life environments and to estimate total walking ground reaction forces GRF(t) using equations of motion. However, for inverse dynamics and clinical gait analysis, the GRF(t) of each foot is required separately. Using an experimental dataset of 1243 tri-axial separate-foot GRF(t) time histories measured by the authors across eight years, this study proposes the ‘Twin Polynomial Method’ (TPM) to estimate the tri-axial left and right foot GRF(t) signals from the total GRF(t) signals. For each gait cycle, TPM fits polynomials of degree five, eight, and nine to the known single-support part of the left and right foot vertical, anterior-posterior, and medial-lateral GRF(t) signals, respectively, to extrapolate the unknown double-support parts of the corresponding GRF(t) signals. Validation of the proposed method both with force plate measurements (gold standard) in the laboratory, and in real-life environment showed a peak-to-peak normalized root mean square error of less than 2.5%, 6.5% and 7.5% for the estimated GRF(t) signals in the vertical, anterior-posterior and medial-lateral directions, respectively. These values show considerable improvement compared with the currently available GRF(t) decomposition methods in the literature.

Association of Sprint Performance With Ground Reaction Forces During Acceleration and Maximal Speed Phases in a Single Sprint

We aimed to clarify the mechanical determinants of sprinting performance during acceleration and maximal speed phases of a single sprint, using ground reaction forces (GRFs). While 18 male athletes performed a 60-m sprint, GRF was measured at every step over a 50-m distance from the start. Variables during the entire acceleration phase were approximated with a fourth-order polynomial. Subsequently, accelerations at 55%, 65%, 75%, 85%, and 95% of maximal speed, and running speed during the maximal speed phase were determined as sprinting performance variables. Ground reaction impulses and mean GRFs during the acceleration and maximal speed phases were selected as independent variables. Stepwise multiple regression analysis selected propulsive and braking impulses as contributors to acceleration at 55%-95% (β > 0.72) and 75%-95% (β > 0.18), respectively, of maximal speed. Moreover, mean vertical force was a contributor to maximal running speed (β = 0.48). The current results demonstrate that exerting a large propulsive force during the entire acceleration phase, suppressing braking force when approaching maximal speed, and producing a large vertical force during the maximal speed phase are essential for achieving greater acceleration and maintaining higher maximal speed, respectively.

A simple method of equine limb force vector analysis and its potential applications

BACKGROUND

Ground reaction forces (GRF) measured during equine gait analysis are typically evaluated by analyzing discrete values obtained from continuous force-time data for the vertical, longitudinal and transverse GRF components. This paper describes a simple, temporo-spatial method of displaying and analyzing sagittal plane GRF vectors. In addition, the application of statistical parametric mapping (SPM) is introduced to analyse differences between contra-lateral fore and hindlimb force-time curves throughout the stance phase. The overall aim of the study was to demonstrate alternative methods of evaluating functional (a)symmetry within horses.

METHODS

GRF and kinematic data were collected from 10 horses trotting over a series of four force plates (120 Hz). The kinematic data were used to determine clean hoof contacts. The stance phase of each hoof was determined using a 50 N threshold. Vertical and longitudinal GRF for each stance phase were plotted both as force-time curves and as force vector diagrams in which vectors originating at the centre of pressure on the force plate were drawn at intervals of 8.3 ms for the duration of stance. Visual evaluation was facilitated by overlay of the vector diagrams for different limbs. Summary vectors representing the magnitude (VecMag) and direction (VecAng) of the mean force over the entire stance phase were superimposed on the force vector diagram. Typical measurements extracted from the force-time curves (peak forces, impulses) were compared with VecMag and VecAng using partial correlation (controlling for speed). Paired samples t-tests (left v. right diagonal pair comparison and high v. low vertical force diagonal pair comparison) were performed on discrete and vector variables using traditional methods and Hotelling's T2 tests on normalized stance phase data using SPM.

RESULTS

Evidence from traditional statistical tests suggested that VecMag is more influenced by the vertical force and impulse, whereas VecAng is more influenced by the longitudinal force and impulse. When used to evaluate mean data from the group of ten sound horses, SPM did not identify differences between the left and right contralateral limb pairs or between limb pairs classified according to directional asymmetry. When evaluating a single horse, three periods were identified during which differences in the forces between the left and right forelimbs exceeded the critical threshold (p < .01).

DISCUSSION

Traditional statistical analysis of 2D GRF peak values, summary vector variables and visual evaluation of force vector diagrams gave harmonious results and both methods identified the same inter-limb asymmetries. As alpha was more tightly controlled using SPM, significance was only found in the individual horse although T2 plots followed the same trends as discrete analysis for the group.

CONCLUSIONS

The techniques of force vector analysis and SPM hold promise for investigations of sidedness and asymmetry in horses.

Genome-wide identification and analysis of the growth-regulating factor family in tobacco (Nicotiana tabacum)

Growth-regulating factors (GRFs) are plant-specific transcription factors that have important functions in regulating plant growth and development. GRF gene families have been described in several plant species, but a comprehensive analysis of the GRF gene family in tobacco has not yet been reported. In this study, we identified 25 NtabGRF genes in N. tabacum. The gene structures, motifs, and cis-acting regulatory elements of the NtabGRF genes were analyzed. Phylogenetic analysis divided the genes into six clusters. Additionally, highly conserved regions of microsynteny were identified in all of the sequenced tobacco species. Expression analysis showed that NtabGRF genes were highly expressed in actively growing tissues and responded to various hormone treatments. Our results provide foundational information about the GRF gene family in tobacco species, and open the door for future research on the functions of these genes.

Timing of Gun Fire Influences Sprinters' Multiple Joint Reaction Times of Whole Body in Block Start

Experienced sprinters are specifically adapted to pre-planning an advanced motor program. Herein, sprinters are able to immediately accelerate their center of mass forward with a whole-body coordinated motion, following a steady state crouched position. We examined the effect of variable timing of reaction signals on multiple joint reaction times (RT) and whole-body RT for specialist sprinters. Twenty well-experienced male sprinters performed five start-dashes from a block start under five variable foreperiod (FP) length conditions (1.465, 1.622, 1.780, 1.938, and 2.096 s), with trials randomly timed between a warning and an imperative tone. Participants’ sprinting motion and ground reaction forces of their four limbs during the block start were measured simultaneously. Whole-body RT was significantly shorter when FP length was longer; the values of whole-body RT were 117 ± 5 ms, 129 ± 5 ms, 125 ± 4 ms, 133 ± 6 ms, and 156 ± 8 ms in the 2.096, 1.938, 1.780, 1.622, and 1.465-s FP-length conditions, respectively. A repeated-measures analysis of variance found a significant joint-by-FP length interaction in joint-moment RT. These findings suggest that FP length affects coordinated motion in four limbs and whole-body RT. This information will be able to lead to new methods for start signals in sprint running events and advance our understanding of the association between FP length and dynamic coordinated motion.

Genome-wide analysis and expression profiling of the GRF gene family in oilseed rape (Brassica napus L.)

Growth regulating-factors (GRFs) are plant-specific transcription factors that help regulate plant growth and development. Genome-wide identification and evolutionary analyses of GRF gene families have been performed in Arabidopsis thaliana, Zea mays, Oryza sativa, and Brassica rapa, but a comprehensive analysis of the GRF gene family in oilseed rape (Brassica napus) has not yet been reported. In the current study, we identified 35 members of the BnGRF family in B. napus. We analyzed the chromosomal distribution, phylogenetic relationships (Bayesian Inference and Neighbor Joining method), gene structures, and motifs of the BnGRF family members, as well as the cis-acting regulatory elements in their promoters. We also analyzed the expression patterns of 15 randomly selected BnGRF genes in various tissues and in plant varieties with different harvest indices and gibberellic acid (GA) responses. The expression levels of BnGRFs under GA treatment suggested the presence of possible negative feedback regulation. The evolutionary patterns and expression profiles of BnGRFs uncovered in this study increase our understanding of the important roles played by these genes in oilseed rape.

Tissue-Specific Regulation of Gma-miR396 Family on Coordinating Development and Low Water Availability Responses

Previously, it was reported that miR396s interact with growth-regulating factors (GRFs) to modulate plant growth, development, and stress resistance. In soybean, 11 gma-miR396 precursors (Pre-miR396a-k) were found, and 24 GmGRFs were predicted as targets of seven mature gma-miR396s (gma-miR396a/b/c/e/h/i/k). To explore the roles of the miR396-GRF module in low water availability response of soybean, we analyzed the expression of Pre-miR396a-k, and found that Pre-miR396a/i/bdgk/e/h were up-regulated in leaves and down-regulated in roots; on the contrary, GmGRF5/6/7/8/15/17/21 were down-regulated in leaves and GmGRF1/2/17/18/19/20/21/22/23/24 were up-regulated in roots of low water potential stressed soybean. Any one of gma-miR396a/b/c/e/h/i/k was able to interact with 20 GmGRFs (GmGRF1/2/6-11/13-24), confirming that this module represents a multi-to-multi network interaction. We generated Arabidopsis plants over-expressing each of the 11 gma-miR396 precursors (Pre-miR396a-k), and seven of them (miR396a/b/c/e/h/i/k-OE transgenic Arabidopsis) showed altered development. The low water availability of miR396a/b/c/e/h/i/k-OE was enhanced in leaves but reduced in seeds and roots. Contrary to previous reports, miR396a/b/c/i-OE seedlings showed lower survival rate than WT when recovering after rewatering under soil drying. In general, we believe our findings are valuable to understand the role of gma-miR396 family in coordinating development and low water availability responses, and can provide potential strategies and directions for soybean breeding programs to improve seed yield and plant drought tolerance.