The differential binding and biological efficacy of auxin herbicides.

BACKGROUND: Auxin herbicides have been used for selective weed control for 75 years and they continue to be amongst the most widely used weed control agents globally. The auxin herbicides fall into five chemical classes, with two herbicides not classified, and in all cases it is anticipated that recognition in the plant starts with binding to the Transport Inhibitor Response 1 (TIR1) family of auxin receptors. There is evidence that some classes of auxins act selectively with certain clades of receptors, although a comprehensive structure-activity relationship has not been available. RESULTS: Using purified receptor proteins to measure binding efficacy we have conducted quantitative structure activity relationship (qSAR) assays using representative members of the three receptor clades in Arabidopsis, TIR1, AFB2 and AFB5. Complementary qSAR data for biological efficacy at the whole-plant level using root growth inhibition and foliar phytotoxicity assays have also been analyzed for each family of auxin herbicides, including for the afb5-1 receptor mutant line. CONCLUSIONS: Comparisons of all these assays highlight differences in receptor selectivity and some systematic differences between results for binding in vitro and activity in vivo. The results could provide insights into weed spectrum differences between the different classes of auxin herbicides, as well as the potential resistance and cross-resistance implications for this herbicide class. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A Retrospective Review of Native Septic Arthritis in Patients: Can We Diagnose Based on Laboratory Values?

Introduction The accurate diagnosis of acute septic arthritis is essential to initiating appropriate treatment and minimizing potential cartilage damage. A synovial fluid cell count of 50,000 cells/mm3 has been used as a diagnostic cutoff for acute septic arthritis, although data supporting this is lacking. The purpose of this study was to assess the efficacy of synovial cell counts to predict septic arthritis in patients with symptomatic native joints. Methods A retrospective review was performed of patients who were evaluated for septic arthritis at a single institution with the use of synovial fluid analysis and adjunctive lab tests. Exclusion criteria included history of a total joint arthroplasty of the affected joint or immunocompromised state. A true infection was considered on the basis of positive or negative synovial aspirate cultures. We evaluated the synovial cell count, synovial polymorphonuclear cell percentile (% neutrophils), serum white blood cell (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) in order to determine their association and predictive power in a true infection. Results Of the 65 patients included in the study, 40 (61.5%) had a positive culture for septic arthritis and 25 (38.5%) had negative cultures. Patients with positive cultures had a larger median % neutrophils than patients with negative cultures (median: 93 vs. median: 86, P=0.041). They also tended to have higher serum CRP levels compared to negative culture patients (median: 142.30 vs. 34.20, P=0.051). No outcomes were independently highly effective in discriminating between patient groups (area under the curve (AUC) ≤ 0.67). There was no significant difference between the synovial cell counts in patients with culture positive septic arthritis and patients with negative cultures (median: 32435 vs 35385, P = 0.94).  Conclusion Patients with culture proven septic arthritis had larger % neutrophils. However, there were no other statistically significant differences between patient groups regarding ESR, CRP, WBC, or cell count aspiration at the time of diagnosis. No synovial cell count level was highly effective in discriminating patients with a positive culture for septic arthritis from patients with negative cultures.

Septic Arthritis in Immunosuppressed Patients: Do Laboratory Values Help?

Previous studies have recommended synovial fluid cell count thresholds of 50,000 cells/mm-3 to diagnose septic arthritis; however, data to support this are limited. It is also unknown if this value is valid in immunosuppressed patients. Methods: We retrospectively reviewed 33 immunosuppressed patients treated at our institution from 2008 to 2018. We compared culture-positive patients with culture-negative patients. Results: We found no statistically significant differences in synovial fluid cell count, percent synovial fluid neutrophils, erythrocyte sedimentation rate, or C-reactive protein between the groups (all P = 0.081). The median synovial fluid cell count in the culture-positive cohort was 29,000 cells/mm-3, with only 31.2% having >50,000 cells/mm-3. Conclusion: Traditional synovial fluid cell thresholds are not a reliable method of diagnosing septic arthritis in immunosuppressed patients.

Energy Dissipation in the Upper Atmospheres of Trappist-1 Planets.

We present a method to quantify the upper-limit of the energy transmitted from the intense stellar wind to the upper atmospheres of three of the Trappist-1 planets (e, f, and g). We use a formalism that treats the system as two electromagnetic regions, where the efficiency of the energy transmission between one region (the stellar wind at the planetary orbits) to the other (the planetary ionospheres) depends on the relation between the conductances and impedances of the two regions. Since the energy flux of the stellar wind is very high at these planetary orbits, we find that for the case of high transmission efficiency (when the conductances and impedances are close in magnitude), the energy dissipation in the upper planetary atmospheres is also very large. On average, the Ohmic energy can reach 0.5 - 1 W/m 2, about 1% of the stellar irradiance and 5-15 times the EUV irradiance. Here, using constant values for the ionospheric conductance, we demonstrate that the stellar wind energy could potentially drive large atmospheric heating in terrestrial planets, as well as in hot jupiters. More detailed calculations are needed to assess the ionospheric conductance and to determine more accurately the amount of heating the stellar wind can drive in close-orbit planets.

Understanding the Differential Response of Setaria viridis L. (green foxtail) and Setaria pumila Poir. (yellow foxtail) to Pyroxsulam.

Green foxtail [Setaria viridis (L) Beauv.] and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult.] are among the most abundant and troublesome annual grass weeds in cereal crops in the Northern Plains of the United States and the Prairie Provinces of Canada. Greenhouse and laboratory experiments were conducted to examine the differential responses of both weed species to foliar applications of the new triazolopyrimidine sulfonamide acetolactate synthase-inhibiting herbicide, pyroxsulam, and to determine the mechanism(s) of differential weed control. Foliar applications of pyroxsulam resulted in >90% control of yellow foxtail at rates between 7.5 and 15 g ai ha-1, whereas the same rates resulted in a reduced efficacy on green foxtail (≤81%). The absorption and translocation of [14C]pyroxsulam in green and yellow foxtail were similar and could not explain the differential whole-plant efficacy. Studies with [14C]pyroxsulam revealed a higher percentage of absorbed pyroxsulam was metabolized into an inactive metabolite in the treated leaf of green foxtail than in the treated leaf of yellow foxtail. Metabolism studies demonstrated that, 48 h after application, 50 and 35% of pyroxsulam in the treated leaf was converted to 5-hydroxy-pyroxsulam in green and yellow foxtail, respectively. The acetolactate synthase (ALS) inhibition assay showed that ALS extracted from green foxtail was more tolerant to pyroxsulam than the enzyme extracted from yellow foxtail was. The in vitro ALS assay showed IC50 values of 8.39 and 0.26 µM pyroxsulam for green and yellow foxtail, respectively. The ALS genes from both green and yellow foxtail were sequenced and revealed amino acid differences; however, the changes are not associated with known resistance-inducing mutations. The differential control of green and yellow foxtail following foliar applications of pyroxsulam was attributed to differences in both metabolism and ALS sensitivity.

Training Intensity Affects Motor Rehabilitation Efficacy Following Unilateral Ischemic Insult of the Sensorimotor Cortex in C57BL/6 Mice.

BACKGROUND: Motor rehabilitative training improves behavioral functionality and promotes beneficial neural reorganization following stroke but is often insufficient to normalize function. Rodent studies have relied on skilled reaching tasks to model motor rehabilitation and explore factors contributing to its efficacy. It has been found that greater training intensity (sessions/day) and duration (training days) facilitates motor skill learning in intact animals. Whether rehabilitative training efficacy varies with intensity following stroke is unclear. METHODS: Mice were trained preoperatively on a skilled reaching task. Following focal ischemic lesions, mice received rehabilitative training either twice daily (high intensity [HI]), once daily (low intensity [LI]), or not at all (control) to determine the effects of rehabilitative training intensity on skilled motor performance. RESULTS: Within 7 days, the HI-trained mice achieved preischemic levels of performance. Mice receiving LI training eventually reached similar performance levels but required a greater quantity of training. Training intensity did not consistently affect the maintenance of performance gains, which were partially lost over time in both groups. DISCUSSION: These data indicate that increased training intensity increases the rate of functional improvements per time and per training session following ischemic insult. Thus, training intensity is an important variable to consider in efforts to optimize rehabilitation efficacy.

Genetic and biochemical evaluation of natural rubber from Eastern Washington prickly lettuce (Lactuca serriola L.).

Alternative sources of natural rubber are of importance due to economic, biological, and political threats that could diminish supplies of this resource. Prickly lettuce (Lactuca serriola L.) synthesizes long-chain natural rubber and was studied to determine underlying genetic and phenotypic characteristics of rubber biosynthesis. Genotypic and phenotypic analysis of an F2 segregating population using EST-SSR markers led to the discovery of genetic regions linked to natural rubber production. Interval mapping (IM) and multiple QTL mapping (MQM) identified several QTL in the mapping population that had significance based on LOD score thresholds. The discovered QTL and the corresponding local markers are genetic resources for understanding rubber biosynthesis in prickly lettuce and could be used in marker-assisted selection (MAS) breeding. Prickly lettuce is an excellent candidate for elucidating the rubber synthesis mechanism and has potential as a crop plant for rubber production.

Post-stroke protection from maladaptive effects of learning with the non-paretic forelimb by bimanual home cage experience in C57BL/6 mice.

Behavioral experience, in the form of skilled limb use, has been found to impact the structure and function of the central nervous system, affecting post-stroke behavioral outcome in both adaptive and maladaptive ways. Learning to rely on the less-affected, or non-paretic, body side is common following stroke in both humans and rodent models. In rats, it has been observed that skilled learning with the non-paretic forelimb following ischemic insult leads to impaired or delayed functional recovery of the paretic limb. Here we used a mouse model of focal motor cortical ischemic injury to examine the effects of non-paretic limb training following unilateral stroke. In addition, we exposed some mice to increased bimanual experience in the home cage following stroke to investigate the impact of coordinated dexterous limb use on the non-paretic limb training effect. Our results confirmed that skilled learning with the non-paretic limb impaired functional recovery following stroke in C56BL/6 mice, as it does in rats. Further, this effect was avoided when the skill learning of the non-paretic limb was coupled with increased dexterous use of both forelimbs in the home cage. These findings further establish the mouse as an appropriate model in which to study the neural mechanisms of recovery following stroke and extend previous findings to suggest that the dexterous coordinated use of the paretic and non-paretic limb can promote functional outcome following injury.

Inheritance and physiological basis for 2,4-D resistance in prickly lettuce (Lactuca serriola L.).

Experiments were conducted to determine the inheritance and physiological basis for resistance to the synthetic auxinic herbicide (2,4-dichlorophenoxy)acetic acid (2,4-D) in a prickly lettuce biotype. Inheritance of 2,4-D resistance in prickly lettuce is governed by a single codominant gene. Absorption and translocation were conducted using (14)C-2,4-D applied to 2,4-D-resistant and -susceptible biotypes. At 96 h after treatment (HAT), the resistant biotype absorbed less applied 2,4-D and retained more 2,4-D in the treated portion of the leaf compared to the susceptible biotype. The resistant biotype translocated less applied 2,4-D to leaves above the treated leaf and crown at 96 HAT compared to the susceptible biotype. No difference in the rate of metabolism of 2,4-D was observed between the two biotypes. Resistance to 2,4-D appears to originate from a reduced growth deregulatory and overstimulation response compared to the susceptible biotype, resulting in lower translocation of 2,4-D in the resistant prickly lettuce biotype.

Uptake, translocation and metabolism of aminocyclopyrachlor in prickly lettuce, rush skeletonweed and yellow starthistle.

BACKGROUND: Aminocyclopyrachlor is a new herbicide proposed to control broadleaf weeds and shrubs in non-crop and rangeland systems. To gain a better understanding of observed field efficacy, the uptake and translocation of foliar-applied aminocyclopyrachlor (DPX-MAT28) and aminocyclopyrachlor methyl ester (DPX-KJM44) were evaluated in two annuals, prickly lettuce (Lactuca serriola L.) and yellow starthistle (Centaurea solstitialis L.), and one perennial, rush skeletonweed (Chondrilla juncea L.). RESULTS: Absorption and translocation varied between species. While absorption of DPX-KJM44 was greater than absorption of DPX-MAT28, rush skeletonweed absorbed the most, followed by yellow starthistle and prickly lettuce. Overall, the total translocation of either herbicide was highest in yellow starthistle, followed by rush skeletonweed and prickly lettuce. Proportional herbicide movement between species was similar, with the majority translocating to developing shoots. However, in rush skeletonweed, early translocation was directed to root tissue. In rush skeletonweed, no DPX-MAT28 metabolism occurred, while DPX-KJM44 was rapidly de-esterified and translocated as DPX-MAT28. CONCLUSION: Aminocyclopyrachlor absorption and translocation are dependent on active ingredient structure and species sensitivity. Highly sensitive species such as prickly lettuce absorb and translocate less material than relatively less sensitive species such as rush skeletonweed. De-esterification of DPX-KJM44 appears to delay translocation of the resulting acid in yellow starthistle and rush skeletonweed.