Surgical treatment of refractory low back pain using implanted BurstDR spinal cord stimulation (SCS) in a cohort of patients without options for corrective surgery: Findings and results from the DISTINCT study, a prospective randomized multi-center-controlled trial.

Background: Low back pain (LBP) is a highly prevalent, disabling condition affecting millions of people. Patients with an identifiable anatomic pain generator and resulting neuropathic lower extremity symptoms often undergo spine surgery, but many patients lack identifiable and/or surgically corrective pathology. Nonoperative treatment options often fail to provide sustained relief. Spinal cord stimulation (SCS) is sometimes used to treat these patients, but the lack of level 1 evidence limits its widespread use and insurance coverage. The DISTINCT RCT study evaluates the efficacy of passive recharge burst SCS compared to conventional medical treatment (CMM) in alleviating chronic, refractory axial low back pain. Methods: This prospective, multicenter, randomized, study with an optional 6-month crossover involved patients who were not candidates for lumbar spine surgery. The primary and secondary endpoints evaluated improvements in low back pain intensity (NRS), back pain-related disability (ODI), pain catastrophizing (PCS), and healthcare utilization. Patients were randomized to SCS therapy or CMM at 30 US study sites. Results: The SCS arm reported an 85.3% NRS responder rate (≥ 50% reduction) compared to 6.2% (5/81) in the CMM arm. After the 6M primary endpoint, SCS patients elected to remain on assigned therapy and 66.2% (49/74) of CMM patients chose to trial SCS (crossover). At the 12M follow-up, SCS and crossover patients reported 78.6% and 71.4% NRS responder rates. Secondary outcomes indicated significant improvements in ODI, PCS, and reduced healthcare utilization. Six serious adverse events were reported and resolved without sequelae. Conclusion: DISTINCT chronic low back pain patients with no indication for corrective surgery experienced a significant and sustained response to burst SCS therapy for up to 12 months. CMM patients who crossed over to the SCS arm reported profound improvements after 6 months. This data advocates for a timely consideration of SCS therapy in patients unresponsive to conservative therapy.

Comparing Conventional Medical Management to Spinal Cord Stimulation for the Treatment of Low Back Pain in a Cohort of DISTINCT RCT Patients.

Aim: Low Back Pain (LBP) is a prevalent condition. Spinal cord stimulation (SCS) has emerged as a more effective, long-term treatment compared to conventional medical management (CMM). The DISTINCT study enrolled and randomized chronic LBP patients with no indication of traditional spine surgery. This analysis focuses comparing study outcomes on patients initially randomized to receive CMM treatment and subsequently crossed over to SCS after 6 months. Purpose: To compare the therapeutic effectiveness and cost-efficiency of passive recharge burst SCS to CMM. Patients and Methods: A total of 269 patients were enrolled with 162 randomly assigned to SCS and 107 to CMM. The DISTINCT study design allowed a crossover to the alternative treatment arm after 6 months. Patients underwent a trial and received a permanent implant if they reported ≥50% pain reduction. Outcome analysis included pain (NRS), disability (ODI), catastrophizing (PCS), quality of life (PROMIS-29) and health care utilization. Results: Seventy out of eighty-one patients opted to cross over to trial SCS at 6M with 94% (66/70) undergoing a trial. Among those, 88% (58/66) reported a ≥50% or more pain relief and 55 received a permanent implant. At 12M visit, 71.4% reported a ≥50% pain improvement sustained at the 18M visit, with 24.5% (12/49) indicating a ≥80% improvement. Disability reductions (79% meeting the minimally important difference of a 13-point decrease), decreased catastrophizing, and significant improvements in all PROMIS-29 domains were noted. Furthermore, 42% of the patients reported decreased or discontinued opioid usage. Clinical benefits at the 12M visit were sustained through the 18M visit accompanied by a significant reduction in healthcare utilization and a $1214 cost savings. Conclusion: SCS demonstrates superior, long-term performance and safety outcomes compared to CMM therapy in LBP patients who received both CMM and SCS therapy. Additionally, SCS patients experienced reduced healthcare resource utilization and lower costs compared to those receiving CMM.

Improvements in Therapy Experience with Evoked Compound Action Potential Controlled, Closed-Loop Spinal Cord Stimulation - Primary Outcome of the ECHO-MAC Randomized Clinical Trial.

Spinal cord stimulation (SCS) is a well-established treatment for chronic neuropathic pain. However, over- or under-delivery of the SCS may occur because the spacing between the stimulating electrodes and the spinal cord is not fixed; spacing changes with motion and postural shifts may result in variable delivery of the SCS dose, and in turn a sub-optimal therapy experience for the patient. The evoked compound action potential (ECAP)-a measure of neural activation - may be used as a control signal to adapt SCS parameters in real-time to compensate for this variability. In this prospective, multicenter, randomized, single-blind, crossover trial, reduction in overstimulation intensity was used as a perceptual measure to evaluate a novel ECAP-controlled, closed-loop (CL) SCS algorithm relative to traditional open-loop (OL) SCS. The primary outcome used a Likert scale to assess sensation during activities of daily living with CL versus OL SCS. Of the 42 subjects in the Intent-to-Treat Analysis set, 97.6% had a reduction in sensation with CL versus OL SCS. The primary objective was met as the lower confidence limit (87.4%) exceeded the performance goal of 50% (p < 0.001). A total of 88.1% (37/42) of subjects preferred CL and 11.9% (5/42) preferred OL SCS. SCS dose consistency during CL SCS was demonstrated by the reduced variability in ECAP amplitude with CL SCS (SD: 8.72 µV) relative to OL SCS (SD: 19.95 µV). Together, these results demonstrate that the ECAP-controlled, CL algorithm reduces or eliminates unwanted sensation, and thereby provides a more preferred and consistent SCS experience. PERSPECTIVE: Patients with chronic pain need durable and dependable options for pain relief. SCS is an important therapy option, and new technology advancements could improve long-term therapy use. Closed-loop SCS offers a preferred and more consistent therapy experience for patients that could lead to increased therapy utilization and reliable therapy outcomes.

Subducting plate structure and megathrust morphology from deep seismic imaging linked to earthquake rupture segmentation at Cascadia.

The origin of rupture segmentation along subduction zone megathrusts and linkages to the structural evolution of the subduction zone are poorly understood. Here, regional-scale seismic imaging of the Cascadia margin is used to characterize the megathrust spanning ~900 km from Vancouver Island to the California border, across the seismogenic zone to a few tens of kilometers from the coast. Discrete domains in lower plate geometry and sediment underthrusting are identified, not evident in prior regional plate models, which align with changes in lithology and structure of the upper plate and interpreted paleo-rupture patches. Strike-slip faults in the lower plate associated with oblique subduction mark boundaries between regions of distinct lower plate geometry. Their formation may be linked to changes in upper plate structure across long-lived upper plate faults. The Juan de Fuca plate is fragmenting within the seismogenic zone at Cascadia as the young plate bends beneath the heterogeneous upper plate resulting in structural domains that coincide with paleo-rupture segmentation.

QTL for the Kinematic Traits That Define the Arabidopsis Root Elongation Zone and Their Relationship to Gravitropism.

Cell expansion in a discrete region called the elongation zone drives root elongation. Analyzing time lapse images can quantify the expansion in kinematic terms as if it were fluid flow. We used horizontal microscopes to collect images from which custom software extracted the length of the elongation zone, the peak relative elemental growth rate (REGR) within it, the axial position of the REGR peak, and the root elongation rate. Automation enabled these kinematic traits to be measured in 1575 Arabidopsis seedlings representing 162 recombinant inbred lines (RILs) derived from a cross of Cvi and Ler ecotypes. We mapped ten quantitative trait loci (QTL), affecting the four kinematic traits. Three QTL affected two or more traits in these vertically oriented seedlings. We compared this genetic architecture with that previously determined for gravitropism using the same RIL population. The major QTL peaks for the kinematic traits did not overlap with the gravitropism QTL. Furthermore, no single kinematic trait correlated with quantitative descriptors of the gravitropism response curve across this population. In addition to mapping QTL for growth zone traits, this study showed that the size and shape of the elongation zone may vary widely without affecting the differential growth induced by gravity.

Modular vector assembly enables rapid assessment of emerging CRISPR technologies.

The diversity of CRISPR systems, coupled with scientific ingenuity, has led to an explosion of applications; however, to test newly described innovations in their model systems, researchers typically embark on cumbersome, one-off cloning projects to generate custom reagents that are optimized for their biological questions. Here, we leverage Golden Gate cloning to create the Fragmid toolkit, a modular set of CRISPR cassettes and delivery technologies, along with a web portal, resulting in a combinatorial platform that enables scalable vector assembly within days. We further demonstrate that multiple CRISPR technologies can be assessed in parallel in a pooled screening format using this resource, enabling the rapid optimization of both novel technologies and cellular models. These results establish Fragmid as a robust system for the rapid design of CRISPR vectors, and we anticipate that this assembly approach will be broadly useful for systematic development, comparison, and dissemination of CRISPR technologies.

Secondary Bony Defects after Soft Tissue Reconstruction in Limb-Threatening Lower Extremity Injuries: Does the Approach to Flap Elevation Matter?

BACKGROUND: Limb-threatening lower extremity injuries often require secondary bone grafting after soft tissue reconstruction. We hypothesized that there would be fewer wound complications when performing secondary bone grafting via a remote surgical approach rather than direct flap elevation. METHODS: A retrospective cohort study was performed at a single Level 1 trauma center comparing complications after secondary bone grafting in patients who had undergone previous soft tissue reconstruction after open tibia fractures between 2006 and 2020. Comparing bone grafting via a remote surgical incision versus direct flap elevation, we evaluated wound dehiscence requiring return to the operating room as the primary outcome. Secondary outcomes were deep infection and delayed amputation. RESULTS: We identified 129 patients (mean age: 40 years, 82% male) with 159 secondary bone grafting procedures. Secondary bone grafting was performed via a remote surgical approach in 54% (n = 86) and direct flap elevation in 46% (n = 73) of cases. Wound dehiscence requiring return to the operating room occurred in one patient in the flap elevation group (1%) and none of the patients in the remote surgical approach. The odds of deep wound infection (OR, 1.77; p = 0.31) or amputation (OR, 1.43; p = 0.73) did not significantly differ between surgical approaches. No significant differences were found in complications between the reconstructive surgeon elevating and re-insetting the flap and the orthopaedic trauma surgeon performing the flap elevation and re-inset. CONCLUSION: Direct flap elevation for secondary bone grafting after soft tissue reconstruction for open tibia fractures did not result in more complications than bone grafting via a remote surgical approach. These findings should reassure surgeons to allow other clinical factors to influence the surgical approach for bone grafting.

Evaluating relationships between seed morphological traits and seed dormancy in Chenopodium quinoa Willd.

Introduction: Quinoa is a high-value, nutritious crop that performs well in variable environments, marginal soils, and in diverse crop rotations. Quinoa's many attributes make it an ideal crop for supporting human health in global communities and economies. To date, quinoa research has largely focused on traits in adult plants important for enhancing plant phenotypic plasticity, abiotic stress, disease resistance, and yield. Fewer studies have evaluated quinoa seed dormancy and suggest that most modern quinoa varieties have weak or no seed dormancy, and a narrow window of seed viability post-harvest. In other crops, diminished seed dormancy is a major risk factor for preharvest sprouting (PHS; germination on the panicle due to rain prior to harvest) and may also pose a similar risk for quinoa. Methods: This study (1) developed a dormancy screening assay to characterize seed dormancy strength in a large collection of quinoa varieties, (2) investigated if morphological variables including seed coat color, seed coat thickness, seed shape including eccentricity which evaluates the roundness or flatness of a seed, and other agronomic traits like crude protein content and seed moisture, contribute to quinoa seed dormancy, and (3) evaluated the use of a phenetic modeling approach to explore relationships between seed morphology and seed dormancy. Results: Dormancy screening indicated seed dormancy ranges in quinoa varieties from none to strong dormancy. Further, phenetic modeling approaches indicate that seed coat thickness and eccentricity are important morphological variables that impact quinoa seed dormancy strength. Conclusions: While dormancy screening and phenetic modeling approaches do not provide a direct solution to preventing PHS in quinoa, they do provide new tools for identifying dormant varieties as well as morphological variables contributing to seed dormancy.

Modular vector assembly enables rapid assessment of emerging CRISPR technologies.

The diversity of CRISPR systems, coupled with scientific ingenuity, has led to an explosion of applications; however, to test newly-described innovations in their model systems, researchers typically embark on cumbersome, one-off cloning projects to generate custom reagents that are optimized for their biological questions. Here, we leverage Golden Gate cloning to create the Fragmid toolkit, a modular set of CRISPR cassettes and delivery technologies, along with a web portal, resulting in a combinatorial platform that enables scalable vector assembly within days. We further demonstrate that multiple CRISPR technologies can be assessed in parallel in a pooled screening format using this resource, enabling the rapid optimization of both novel technologies and cellular models. These results establish Fragmid as a robust system for the rapid design of CRISPR vectors, and we anticipate that this assembly approach will be broadly useful for systematic development, comparison, and dissemination of CRISPR technologies.

Patch Track Software for Measuring Kinematic Phenotypes of Arabidopsis Roots Demonstrated on Auxin Transport Mutants.

Plant roots elongate when cells produced in the apical meristem enter a transient period of rapid expansion. To measure the dynamic process of root cell expansion in the elongation zone, we captured digital images of growing Arabidopsis roots with horizontal microscopes and analyzed them with a custom image analysis program (PatchTrack) designed to track the growth-driven displacement of many closely spaced image patches. Fitting a flexible logistics equation to patch velocities plotted versus position along the root axis produced the length of the elongation zone (mm), peak relative elemental growth rate (% h-1), the axial position of the peak (mm from the tip), and average root elongation rate (mm h-1). For a wild-type root, the average values of these kinematic traits were 0.52 mm, 23.7% h-1, 0.35 mm, and 0.1 mm h-1, respectively. We used the platform to determine the kinematic phenotypes of auxin transport mutants. The results support a model in which the PIN2 auxin transporter creates an area of expansion-suppressing, supraoptimal auxin concentration that ends 0.1 mm from the quiescent center (QC), and that ABCB4 and ABCB19 auxin transporters maintain expansion-limiting suboptimal auxin levels beginning approximately 0.5 mm from the QC. This study shows that PatchTrack can quantify dynamic root phenotypes in kinematic terms.

Optimization of Cas12a for multiplexed genome-scale transcriptional activation.

Cas12a CRISPR technology, unlike Cas9, allows for facile multiplexing of guide RNAs from a single transcript, simplifying combinatorial perturbations. While Cas12a has been implemented for multiplexed knockout genetic screens, it has yet to be optimized for CRISPR activation (CRISPRa) screens in human cells. Here, we develop a new Cas12a-based transactivation domain (TAD) recruitment system using the ALFA nanobody and demonstrate simultaneous activation of up to four genes. We screen a genome-wide library to identify modulators of growth and MEK inhibition, and we compare these results with those obtained with open reading frame (ORF) overexpression and Cas9-based CRISPRa. We find that the activity of multiplexed arrays is largely predictable from the best-performing guide and provide criteria for selecting active guides. We anticipate that these results will greatly accelerate the exploration of gene function and combinatorial phenotypes at scale.

Treatment of Refractory Low Back Pain Using Passive Recharge Burst in Patients Without Options for Corrective Surgery: Findings and Results From the DISTINCT Study, a Prospective Randomized Multicenter Controlled Trial.

OBJECTIVE: Spinal cord stimulation (SCS) is effective for relieving chronic intractable pain conditions. The Dorsal spInal cord STImulatioN vs mediCal management for the Treatment of low back pain study evaluates the effectiveness of SCS compared with conventional medical management (CMM) in the treatment of chronic low back pain in patients who had not undergone and were not candidates for lumbar spine surgery. METHODS AND MATERIALS: Patients were randomized to passive recharge burst therapy (n = 162) or CMM (n = 107). They reported severe pain and disability for more than a decade and had failed a multitude of therapies. Common diagnoses included degenerative disc disease, spondylosis, stenosis, and scoliosis-yet not to a degree amenable to surgery. The six-month primary end point compared responder rates, defined by a 50% reduction in pain. Hierarchical analyses of seven secondary end points were performed in the following order: composite responder rate (numerical rating scale [NRS] or Oswestry Disability Index [ODI]), NRS, ODI, Pain Catastrophizing Scale responder rate, Patient Global Impression of Change (PGIC) responder rate, and Patient-Reported Outcome Measure Information System-29 in pain interference and physical function. RESULTS: Intention-to-treat analysis showed a significant difference in pain responders on NRS between SCS (72.6%) and CMM (7.1%) arms (p < 0.0001). Of note, 85.2% of those who received six months of therapy responded on NRS compared with 6.2% of those with CMM (p < 0.0001). All secondary end points indicated the superiority of burst therapy over CMM. A composite measure on function or pain relief showed 91% of subjects with SCS improved, compared with 16% of subjects with CMM. A substantial improvement of 30 points was observed on ODI compared with a

Use of a mixed reality system for navigational mapping during cardiac electrophysiological testing does not prolong case duration: A subanalysis from the Cardiac Augmented REality study.

Background: CommandEP™ is a mixed reality (MXR) system for cardiac electrophysiological (EP) procedures that provides a real-time 3-dimensional digital image of cardiac geometry and catheter locations. In a previous study, physicians using the system demonstrated improved navigational accuracy. This study investigated the impact of the CommandEP system on EP procedural times compared to the standard-of-care electroanatomic mapping system (EAMS) display. Objective: The purpose of this retrospective case-controlled analysis was to evaluate the impact of a novel MXR interface on EP procedural times compared to a case-matched cohort. Methods: Cases from the Cardiac Augmented REality (CARE) study were matched for diagnosis and weight using a contemporary cohort. Procedural time was compared from the roll-in and full implementation cohort. During routine EP procedures, operators performed tasks during the postablation waiting phase, including creation of cardiac geometry and 5-point navigation under 2 conditions: (1) EAMS first; and (2) CommandEP. Results: From a total of 16 CARE study patients, the 10 full implementation patients were matched to a cohort of 20 control patients (2 controls:1 CARE, matched according to pathology and age/weight). No statistical difference in total case times between CARE study patients vs control group (118 ± 29 minutes vs 97 ± 20 minutes; P = .07) or fluoroscopy times (6 ± 4 minutes vs 7 ± 6 minutes; P = .9). No significant difference in case duration for CARE study patients comparing roll-in vs full-implementation cohort (121 ± 26 minutes vs 118 ± 29 minutes; P = .96). CommandEP wear time during cases was significantly longer in full implementation cases (53 ± 24 minutes vs 24 ± 5 minutes; P = .0009). During creation of a single cardiac geometry, no significant time difference was noted between CommandEP vs EAMS (284 ± 45 seconds vs 268 ± 43 seconds; P = .1) or fluoroscopy use (9 ± 19 seconds vs 6 ± 18 seconds; P = .25). During point navigation tasks, there was no difference in total time (CommandEP 31 ± 14 seconds vs EAMS 28 ± 15 seconds; P = .16) or fluoroscopy time (CommandEP 0 second vs EAMS 0 second). Conclusion: MXR did not prolong overall procedural time compared to a matched cohort. There was no prolongation in study task completion time. Future studies with experienced CommandEP users directly assessing procedural time and task completion time in a randomized study population would be of interest.

Incidence of Complications Associated With Lipectomy Techniques and Patient Body Mass Index: An Institutional and National Analysis Using the Tracking Operations and Outcomes for Plastic Surgeons.

INTRODUCTION: An evaluation of complication rates in different abdominal lipectomy techniques with relationship to body mass index (BMI) and other risk factors. METHODS: We identified patients who underwent an abdominal lipectomy at our institution from January 2015 to July 2020. Those with concurrent hernia repair were excluded. Patients were classified into 2 groups: (1) horizontal lipectomy with or without umbilical translocation and (2) inverted-T lipectomy with translocation. Demographics, operative details, and postoperative complications were collected for 1 year postoperatively. Bivariate analyses were conducted to determine factors associated with type of procedure and complications. Crude and stratum-specific (based on BMI) odds ratios for complications were calculated for the inverted T as compared with the horizontal group. A replicate analysis using the national Tracking Operations and Outcomes for Plastic Surgeons (TOPS) as a single cohort was performed. RESULTS: At our institution, 362 patients (group 1 = 196, group 2 = 166) were included. A total of 40.9% of patients experienced at least one complication at 1 year postoperatively with the complication rate decreasing to 28.0% when analyzed at the 30-day postoperative period. Specifically, wound disruption rates were highest in group 2 (39.8%) compared with group 1 (15.6%; P < 0.0001). The odds of experiencing a complication were greater in the inverted-T group overall and within each stratum of BMI. When dividing the cohort based on BMI class (normal weight, overweight, class I, class II, and class III obesity), the incidence of wound disruption increased as did BMI (2.6%, 22.2%, 27.2%, 48.2%, and 56.3%, respectively; P < 0.0001). The TOPS data set included 23,067 patients and showed an overall complication rate of 13.1% at 30-day postop. Overall, wound disruption rate was 4.6%. Compared with normal weight patients, the odds of experiencing a complication trended higher with each stratum of BMI. Other factors associated with complications included BMI, tobacco use, diabetes, American Society of Anesthesiology, prior massive weight loss, and LOS. CONCLUSIONS: The increasing complication rate within each BMI stratum of the large sample size of the TOPS patient cohort, in addition to our similar institutional trends, suggests that a staged procedure may be more appropriate for higher BMI patients. Surgical technique modification with limited flap undermining in patients undergoing inverted-T lipectomy to preserve flap perfusion may also decrease overall complication rates.

A comprehensive characterization of agronomic and end-use quality phenotypes across a quinoa world core collection.

Quinoa (Chenopodium quinoa Willd.), a pseudocereal with high protein quality originating from the Andean region of South America, has broad genetic variation and adaptability to diverse agroecological conditions, contributing to the potential to serve as a global keystone protein crop in a changing climate. However, the germplasm resources currently available to facilitate quinoa expansion worldwide are restricted to a small portion of quinoa's total genetic diversity, in part because of day-length sensitivity and issues related to seed sovereignty. This study aimed to characterize phenotypic relationships and variation within a quinoa world core collection. The 360 accessions were planted in a randomized complete block design with four replicates in each of two greenhouses in Pullman, WA during the summer of 2018. Phenological stages, plant height, and inflorescence characteristics were recorded. Seed yield, composition, thousand seed weight, nutritional composition, shape, size, and color were measured using a high-throughput phenotyping pipeline. Considerable variation existed among the germplasm. Crude protein content ranged from 11.24% to 17.81% (fixed at 14% moisture). We found that protein content was negatively correlated with yield and positively correlated with total amino acid content and days to harvest. Mean essential amino acids values met adult daily requirements but not leucine and lysine infant requirements. Yield was positively correlated with thousand seed weight and seed area, and negatively correlated with ash content and days to harvest. The accessions clustered into four groups, with one-group representing useful accessions for long-day breeding programs. The results of this study establish a practical resource for plant breeders to leverage as they strategically develop germplasm in support of the global expansion of quinoa.

Fishing through the cracks: The unregulated nature of global squid fisheries.

While most research has focused on the legality of global industrial fishing, unregulated fishing has largely escaped scrutiny. Here, we evaluate the unregulated nature of global squid fisheries using AIS data and nighttime imagery of the globalized fleet of light-luring squid vessels. We find that this fishery is extensive, fishing 149,000 to 251,000 vessel days annually, and that effort increased 68% over the study period 2017-2020. Most vessels are highly mobile and fish in multiple regions, largely (86%) in unregulated areas. While scientists and policymakers express concerns over the declining abundance of squid stocks globally and regionally, we find a net increase in vessels fishing squid globally and spatial expansion of effort to novel areas. Since fishing effort is static in areas with increasing management, and rising in unmanaged areas, we suggest actors may take advantage of fragmented regulations to maximize resource extraction. Our findings highlight a profitable, but largely unregulated fishery, with strong potential for improved management.

Tracking elusive and shifting identities of the global fishing fleet.

Illegal, unreported, and unregulated (IUU) fishing costs billions of dollars per year and is enabled by vessels obfuscating their identity. Here, we combine identities of ~35,000 vessels with a decade of GPS data to provide a global assessment of fishing compliance, reflagging patterns, and fishing by foreign-owned vessels. About 17% of high seas fishing is by potentially unauthorized or internationally unregulated vessels, with hot spots of this activity in the west Indian and the southwest Atlantic Oceans. In addition, reflagging, a tactic often used to obscure oversight, occurs in just a few ports primarily by fleets with high foreign ownership. Fishing by foreign-owned vessels is concentrated in parts of high seas and certain national waters, often flying flags of convenience. These findings can address the global scope of potential IUU fishing and enable authorities to improve oversight.

Whiskers provide time-series of toxic and essential trace elements, Se:Hg molar ratios, and stable isotope values of an apex Antarctic predator, the leopard seal.

In an era of rapid environmental change and increasing human presence, researchers need efficient tools for tracking contaminants to monitor the health of Antarctic flora and fauna. Here, we examined the utility of leopard seal whiskers as a biomonitoring tool that reconstructs time-series of significant ecological and physiological biomarkers. Leopard seals (Hydrurga leptonyx) are a sentinel species in the Western Antarctic Peninsula due to their apex predator status and top-down effects on several Antarctic species. However, there are few data on their contaminant loads. We analyzed leopard seal whiskers (n = 18 individuals, n = 981 segments) collected during 2018-2019 field seasons to acquire longitudinal profiles of non-essential (Hg, Pb, and Cd) and essential (Se, Cu, and Zn) trace elements, stable isotope (ẟ15N and ẟ13C) values and to assess Hg risk with Se:Hg molar ratios. Whiskers provided between 46 and 286 cumulative days of growth with a mean ~ 125 days per whisker (n = 18). Adult whiskers showed variability in non-essential trace elements over time that could partly be explained by changes in diet. Whisker Hg levels were insufficient (<20 ppm) to consider most seals being at "high" risk for Hg toxicity. Nevertheless, maximum Hg concentrations observed in this study were greater than that of leopard seal hair measured two decades ago. However, variation in the Se:Hg molar ratios over time suggest that Se may detoxify Hg burden in leopard seals. Overall, we provide evidence that the analysis of leopard seal whiskers allows for the reconstruction of time-series ecological and physiological data and can be valuable for opportunistically monitoring the health of the leopard seal population and their Antarctic ecosystem during climate change.

BRXL4-LAZY1 interaction at the plasma membrane controls Arabidopsis branch angle and gravitropism.

Gravitropism guides growth to shape plant architecture above and below ground. Mutations in LAZY1 impair stem gravitropism and cause less upright inflorescence branches (wider angles). The LAZY1 protein resides at the plasma membrane and in the nucleus. The plasma membrane pool is necessary and sufficient for setting branch angles. To investigate the molecular mechanism of LAZY1 function, we screened for LAZY1-interacting proteins in yeast. We identified BRXL4, a shoot-specific protein related to BREVIS RADIX. The BRXL4-LAZY1 interaction occurred at the plasma membrane in plant cells, and not detectably in the nucleus. Mutations in the C-terminus of LAZY1, but not other conserved regions, prevented the interaction. Opposite to lazy1, brxl4 mutants displayed faster gravitropism and more upright branches. Overexpressing BRXL4 produced strong lazy1 phenotypes. The apparent negative regulation of LAZY1 function is consistent with BRXL4 reducing LAZY1 expression or the amount of LAZY1 at the plasma membrane. Measurements indicated that both are true. LAZY1 mRNA was three-fold more abundant in brxl4 mutants and almost undetectable in BRXL4 overexpressors. Plasma membrane LAZY1 was higher and nuclear LAZY1 lower in brxl4 mutants compared with the wild type. To explain these results, we suggest that BRXL4 reduces the amount of LAZY1 at the plasma membrane where it functions in gravity signaling and promotes LAZY1 accumulation in the nucleus where it reduces LAZY1 expression, possibly by suppressing its own transcription. This explanation of how BRXL4 negatively regulates LAZY1 suggests ways to modify shoot system architecture for practical purposes.