As tawny crazy ants (Nylanderia fulva) invade the southern United States, they often displace imported fire ants (Solenopsis invicta). After exposure to S. invicta venom, N. fulva applies abdominal ...exocrine gland secretions to its cuticle. Bioassays reveal that these secretions detoxify S. invicta venom. Further, formic acid from N. fulva venom is the detoxifying agent. N. fulva exhibits this detoxification behavior after conflict with a variety of ant species; however, it expresses it most intensely after interactions with S. invicta. This behavior may have evolved in their shared South American native range. The capacity to detoxify a major competitor's venom probably contributes substantially to its ability to displace S. invicta populations, making this behavior a causative agent in the ecological transformation of regional arthropod assemblages.
MutS homologs (MSHs) are highly conserved core components of DNA mismatch repair. Mismatch recognition provokes ATP-binding by MSH proteins that drives a conformational transition from a short-lived ...lesion-searching clamp to an extremely stable sliding clamp on the DNA. Here, we have expanded on previous bulk biochemical studies to examine the stability, lifetime, and kinetics of bacterial and human MSH sliding clamps on mismatched DNA using surface plasmon resonance and single-molecule analysis of fluorescently labeled proteins. We found that ATP-bound MSH complexes bound to blocked-end or very long mismatched DNAs were extremely stable over a range of ionic conditions. These observations underpinned the development of a high-throughput Förster resonance energy transfer system that specifically detects the formation of MSH sliding clamps on mismatched DNA. The Förster resonance energy transfer system is capable of distinguishing between HsMSH2-HsMSH3 and HsMSH2-HsMSH6 and appears suitable for chemical inhibitor screens. Taken together, our results provide additional insight into MSH sliding clamps as well as methods to distinguish their functions in mismatch repair.
•Fluorescent cationic starch nanoparticles can assist caries detection.•Targeted nanoparticles illuminate caries with high sensitivity and specificity.•Fluorescent nanoparticles enhance detection of ...early enamel caries lesions.
We have previously shown fluorescent cationic starch nanoparticles (FCSNs) penetrate enamel surface porosity of active carious lesions, potentially aiding their detection. Here, we evaluate the in vitro diagnostic accuracy of FCSNs in detecting occlusal caries compared to histologic reference standard.
100 extracted human teeth were selected with sound (50), or either non-cavitated (25) or cavitated (25) lesions. A region of interest (ROI) on the occlusal surface was assessed for fluorescence by two independent examiners, after immersion in FCSN solution, water rinse, and illumination by dental curing lamp viewed through orange UV-filter glasses. ROIs were sectioned and evaluated by histology (Downer Criteria) as a gold standard for caries presence. Cohen's Kappa was determined for inter- and intra-examiner agreement, and sensitivity, specificity, and area under the curve of Receiver Operator Curves (ROCAUC) were calculated. The analysis was repeated for the subset of “early” lesions, defined as being limited to enamel.
FCSN use resulted in substantial inter-user (k=0.74±0.07), and high intra-user agreement (k=0.80±0.06; 0.94±0.03, by examiner). Sensitivity, specificity and ROCAUC for FCSNs were 88.9%; 94.6%; 0.92±0.06 for all, and 76.9%, 94.6%, and 0.86±0.10 for early lesions. In post hoc analysis, sensitivity seemed to be greater with the FCSN than the expert visual exam, particularly for early lesions.
FCSNs are a reproducible and accurate novel technology for occlusal caries detection, with high sensitivity and specificity compared to histology. Future clinical validation is necessary. FCSNs can improve early caries detection and shift treatment towards non-invasive approaches, improving oral health.
There is an acute need for materials that can store the toxic and highly reactive diborane gas at room temperature. In this work, the interfacial chemistry leading to safe and reversible storage of ...diborane (B
H
) in the UiO-66-NH
metal-organic framework (MOF) was investigated via
transmission infrared (IR) spectroscopy, temperature-programmed desorption (TPD), and electronic structure calculations. The infrared spectrum of B
H
adsorbed within UiO-66-NH
indicates hydrogen bonding with the μ
-OH groups of the MOF nodes and chemisorption at the -NH
groups of the MOF linkers. The conversion of physisorbed to chemisorbed diborane, as observed through a spectroscopically unique intermediate species, occurred over a broad temperature regime from 80 to 410 K. During B
H
-TPD studies, both the weakly and strongly bound species were found to desorb exclusively as molecular B
H
. Infrared spectroscopic studies, performed during diborane adsorption and reaction, combined with electronic structure calculations, revealed that chemisorption occurred via a reversible dissociation reaction involving a "half-open" B
H
intermediate and resulted in the formation of two NH
-bound BH
units, which leave the MOF as B
H
via recombinative desorption. The close spacing of -NH
groups in the UiO-66-NH
MOF is key to enabling high-temperature chemisorptive storage of B
H
, and the spatial arrangement of the amine groups has a significant effect on the dissociation energy profile. This work demonstrates that reversible dissociation of B
H
on precisely engineered, nucleophile-rich materials represents a promising pathway to diborane stabilization and long-term storage.
We examine whether one of the most popular observation systems in teacher evaluation—the Framework for Teaching (FFT)—captures the range of instructional skills teachers need to be effective. We ...focus on the case of special educators, who are likely to use instructional approaches that, although supported by research, are de-emphasized in common observation systems. Drawing on 206 lessons from 51 teachers, we compare FFT scores to an observation system from special education. We find that FFT’s psychometric properties are consistent with previous studies, but the system is limited in assessing the quality of instructional practices used in special education. We discuss implications of these findings for two practical uses of observations—supporting teacher development and informing human capital decisions.
Sensitive detection of low-abundance proteins in complex biological samples has typically been achieved by immunoassays that use antibodies specific to target proteins; however, de novo development ...of antibodies is associated with high costs, long development lead times, and high failure rates. To address these challenges, we developed an antibody-free strategy that involves PRISM (high-pressure, high-resolution separations coupled with intelligent selection and multiplexing) for sensitive selected reaction monitoring (SRM)–based targeted protein quantification. The strategy capitalizes on high-resolution reversed-phase liquid chromatographic separations for analyte enrichment, intelligent selection of target fractions via on-line SRM monitoring of internal standards, and fraction multiplexing before nano–liquid chromatography-SRM quantification. Application of this strategy to human plasma/serum demonstrated accurate and reproducible quantification of proteins at concentrations in the 50–100 pg/mL range, which represents a major advance in the sensitivity of targeted protein quantification without the need for specific-affinity reagents. Application to a set of clinical serum samples illustrated an excellent correlation between the results obtained from the PRISM-SRM assay and those from clinical immunoassay for the prostate-specific antigen level.
Danielson’s Framework for Teaching (FFT) is currently used in more than 20 states to inform teacher evaluation and professional learning. To investigate whether FFT promotes instruction that ...appropriately responds to the needs of students with learning disabilities, we conduct a systematic content analysis of the instructional approach emphasized in the FFT’s Instructional Domain (Domain 3) of Danielson’s FFT. We frame our study using cognitive load theory and research regarding effective instruction for students with disabilities. We end by discussing implications regarding the evaluation and development of effective teaching for students with learning disabilities.
Abstract Private wells often lack centralized oversight, drinking water quality standards, and consistent testing methodologies. For lead in well water, the lack of standardized data collection ...methods can impact reported measurements, which can misinform health risks. Here, we conducted a targeted community science testing of 1143 wells across 17 counties in North Carolina (USA) and compared results to state testing data primarily associated with new well construction compiled in the NCWELL database. The goal of our study was to explore the impacts of sampling methodology and household representation on estimated lead exposures and subsequent health risks. At the household scale, we illustrated how sampling and analytical techniques impact lead measurements. The community science testing first draw samples (characterizing drinking water) had a 90th percentile lead value of 12.8 μ g l −1 while the NCWELL database flushed samples (characterizing groundwater) had a value below the reporting level of 5 μ g l −1 . As lead was associated with the corrosion of premise plumbing, flushing prior to collection substantially reduced lead concentrations. At the community scale, we examined how the lack of representation based on household demographics and well construction characteristics impacted the knowledge of lead and blood lead level (BLL) occurrence. When simulating representative demographics of the well populations, we observed that the 90th percentile lead level could differ by up to 6 μ g l −1 , resulting in communities being above the USEPA action level. This translated to a 1.0–1.3 μ g dl −1 difference in predicted geometric mean BLL among infants consuming reconstituted formula. Further, inclusion of less common well construction types also increased lead in water occurrence. Overall, under- and overestimations of lead concentrations associated with differences in sampling techniques and sample representation can misinform conclusions about risks of elevated BLLs associated with drinking water from private wells which may hinder investigations of waterborne lead exposure.
Several large-scale survey efforts have attempted to understand teachers’ experiences in the early months of the pandemic. Our study complements this literature by providing direct evidence of ...teachers’ work prior to and after the onset of COVID-19. We leverage unique longitudinal time use and affect data on 131 teachers from one district across the 2019–2020 school year. Specifically, we provide a full accounting of teachers’ instructional activities, their reports of their positive affect and negative affect while engaged in these activities, and the extent to which teachers’ work experiences changed post-COVID. Our results suggest a large reduction in teachers’ daily instructional minutes, which were replaced with increased planning, paperwork, and interactions with colleagues and parents. Teachers’ overall positive and negative affect did not change post-COVID. But teachers’ affective responses to specific work activities did. Post-COVID, we saw increases in teachers’ positive affect when with students.
The use of the psychedelic compound psilocybin in conjunction with psychotherapy has shown promising results in the treatment of psychiatric disorders, though the underlying mechanisms supporting ...these effects remain unclear. Psilocybin is a Schedule I substance that is dephosphorylated
to form an active metabolite, psilocin. Psilacetin, also known as O-acetylpsilocin or 4-acetoxy-N,N-dimethyltryptamine (4-AcO-DMT), is an unscheduled compound that has long been suggested as an alternative psilocin prodrug, though direct
support for this hypothesis has thus far been lacking.
This study employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to assess the time-course and plasma concentrations of psilocin following the intraperitoneal (IP) administration of psilacetin fumarate or psilocybin to male and female C57Bl6/J mice.
Direct comparisons of the time courses for psilocin exposure arising from psilocybin and psilacetin found that psilocybin led to 10-25% higher psilocin concentrations than psilacetin at 15-min post-injection. The half-life of psilocin remained approximately 30 min, irrespective of whether it came from psilocybin or psilacetin. Overall, the relative amount of psilocin exposure from psilacetin fumarate was found to be approximately 70% of that from psilocybin.
These findings provide the first direct support for the long-standing assumption in the field that psilacetin functions as a prodrug for psilocin
. In addition, these results indicate that psilacetin fumarate results in lower peripheral psilocin exposure than psilocybin when dosed on an equimolar basis. Thoughtful substitution of psilocybin with psilacetin fumarate appears to be a viable approach for conducting mechanistic psychedelic research in C57Bl6/J mice.
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