The effect of molecular crowding on the stability of human c-MYC promoter sequence I-motif at neutral pH.

We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). In terms of drug targeting, the question is whether c-MYC promoter sequence i-motifs will exist in the nucleus at neutral pH. In this work, we have investigated the stability of a mutant c-MYC i-motif in solutions containing a molecular crowding agent. The crowded nuclear environment was modeled by the addition of up to 40% w/w polyethylene glycols having molecular weights up to 12,000 g/mol. CD and DSC were used to establish the presence and stability of c-MYC i-motifs in buffer solutions over the pH range 4 to 7. We have shown that the c-MYC i-motif can exist as a stable structure at pH values as high as 6.7 in crowded solutions. Generic dielectric constant effects, e.g., a shift in the pKa of cytosine by more than 2 units (e.g., 4.8 to 7.0), or the formation of non-specific PEG/DNA complexes appear to contribute insignificantly to i-motif stabilization. Molecular crowding, largely an excluded volume effect of added PEG, having a molecular weight in excess of 1,000 g/mol, appears to be responsible for stabilizing the more compact i-motif over the random coil at higher pH values.

Maize grain yield enhancement in modern hybrids associated with greater stalk lodging resistance at a high planting density: a case study in northeast China.

Lodging resistance is a critical trait in modern maize breeding. This study aimed to examine maize stalk lodging and its related characteristics in response to increasing planting densities in modern hybrids. A two-year field trial was conducted from 2018 to 2019 with two widely grown commercial hybrids ('Xy335' and 'Fm985') and three planting density treatments of 4.5 × 104 (low density, LD), 6.5 × 104 (medium density, MD), and 8.5 × 104 plants/ha (high density, HD). New hybrid Fm985 had a significantly higher grain yield and lower lodging rate at HD, while there was no significance at LD and MD. Compared to Fm985, old hybrid Xy335 had a significantly high plant height, ear and gravity height, and culm length (CL) across the three planting densities, while opposite stalk bending strength (SBS), dry weight per unit length (DWPU), cross-sectional area, and the cellulose and lignin content in the basal internode were low. Correlation and path analysis revealed that kernel number per ear and lodging rate directly contributed to maize grain yield, while lodging-related traits of SBS, stem lignin, and DWPU had an indirect effect on maize grain yield, suggesting that modern hybrid maize yield enhancement is associated with greater stalk lodging resistance at a high planting density in northeast China.

Distribution and assessment of heavy metal in sediments of Malacca Strait.

In this study, we explored the heavy metal elements in 42 surface sediments from the Malacca Strait in terms of distribution, controlling factors, environmental quality, and primary sources. An analysis of grain size revealed finer sediments near the coast of Malaysia, which gradually thickened toward offshore. In addition, heavy metal elements were abundantly distributed near the coastal area of Malaysia, with a gradual decrease toward the sea; their content increased within waters close to the Perak estuary. Source analysis of heavy metals showed that Cr, Hg, Zn, Cd, and Cu were mostly derived from natural weathering, and their distribution was significantly influenced by sediment grain size. As and Pb were affected by human activities. The environmental quality assessment results showed that Cu, Cr, Cd, and Zn in our study regions were pollution-free. Pb elements showed low-to-moderate pollution, and Hg showed a certain degree of ecological risk due to its high toxicity coefficient. The content of As elements in surface sediments increased significantly when compared to the background value, with several evaluation methods indicating a high-risk index. According to these findings, the area near the mouth of the Perak River is the most polluted, followed by the surrounding coastal areas.

Comparative Study of the Adverse Events Associated With Adjuvant Use of Dexmedetomidine and Clonidine in Local Anesthesia.

Background: Although clonidine and dexmedetomidine are used as alpha-2 agonists to improve the quality and duration of blockade induced by local anesthetics, no study has been reported to compare their associated adverse events in local anesthesia. The aim of this study is to compare the adverse events associated with the adjuvant use of dexmedetomidine and clonidine in local anesthesia. Methods: A comprehensive search was performed to retrieve any reported adverse event associated with adjuvant use of dexmedetomidine and clonidine in local anesthesia from published literature up to 1 July 2020. Assessment of the quality of included studies was performed by the Jadad score. A comparison of any reported adverse event was made between interventions by pooling data from studies using a direct meta-analysis technique. Dichotomous outcomes were summarized as risk ratios. The review was performed according to PRISMA guideline. Results: From 121 articles retrieved from the search finally 14 articles including 1,120 patients had eligibility criteria for including in the meta-analysis. No significant difference was observed between bradycardia/hypotension (OR = 1.17; 95 % CI = 0.66-2.10; P = 0.580; I 2 = 53.78 %, P = 0.027), nausea/vomiting (OR = 0.91; 95% CI = 0.59-1.42; P = 0.706; I 2 = 0.0 %, P = 0.940) dizziness/headache (OR = 1.10; 95% CI = 0.44-2.75; P = 0.831; I 2 = 0.0 %, P = 0.882) shivering (OR = 0.95 % CI = 0.50-1.66; P = 0.831; I 2 = 0.0 %, P = 0.920) and dry mouth (OR = 1.00; 95 % CI = 0.50-1.96; P = 0.996; I 2 = 0.0%, P = 0.900). No significant difference was observed in subgroup comparison of adverse events in the intravenous or local adjuvant use of the study drugs (p > 0.05). Conclusion: There is no difference in adverse events associated with the intravenous or local adjuvant use of dexmedetomidine and clonidine in local anesthesia.

Visualizing the Calcitonin Gene-Related Peptide Immunoreactive Innervation of the Rat Cranial Dura Mater with Immunofluorescence and Neural Tracing.

The aim of this study was to examine the distribution and origin of the calcitonin gene-related peptide (CGRP)-immunoreactive sensory nerve fibers of the cranial dura mater using immunofluorescence, three-dimensional (3D) reconstruction and retrograde tracing technique. Here, the nerve fibers and blood vessels were stained using immunofluorescence and histochemistry techniques with CGRP and fluorescent phalloidin, respectively. The spatial correlation of dural CGRP-immuoreactive nerve fibers and blood vessels were demonstrated by 3D reconstruction. Meanwhile, the origin of the CGRP-immunoreactive nerve fibers were detected by neural tracing technique with fluorogold (FG) from the area around middle meningeal artery (MMA) in the cranial dura mater to the trigeminal ganglion (TG) and cervical (C) dorsal root ganglia (DRGs). In addition, the chemical characteristics of FG-labeled neurons in the TG and DRGs were also examined together with CGRP using double immunofluorescences. Taking advantage of the transparent whole-mount sample and 3D reconstruction, it was shown that CGRP-immunoreactive nerve fibers and phalloidin-labeled arterioles run together or separately forming a dural neurovascular network in a 3D view, while the FG-labeled neurons were found in the ophthalmic, maxillary, and mandibular branches of TG, as well as the C2-3 DRGs ipsilateral to the side of tracer application in which some of FG-labeled neurons presented with CGRP-immunoreactive expression. With these approaches, we demonstrated the distributional characteristics of CGRP-immunoreactive nerve fibers around the blood vessels in the cranial dura mater, as well as the origin of these nerve fibers from TG and DRGs. From the perspective of methodology, it may provide a valuable reference for understanding the complicated neurovascular structure of the cranial dura mater under the physiological or pathological condition.

Upregulation of large myelin protein zero leads to Charcot-Marie-Tooth disease-like neuropathy in mice.

Charcot-Marie-Tooth (CMT) disease is a hereditary neuropathy mainly caused by gene mutation of peripheral myelin proteins including myelin protein zero (P0, MPZ). Large myelin protein zero (L-MPZ) is an isoform of P0 that contains an extended polypeptide synthesized by translational readthrough at the C-terminus in tetrapods, including humans. The physiological role of L-MPZ and consequences of an altered L-MPZ/P0 ratio in peripheral myelin are not known. To clarify this, we used genome editing to generate a mouse line (L-MPZ mice) that produced L-MPZ instead of P0. Motor tests and electrophysiological, immunohistological, and electron microscopy analyses show that homozygous L-MPZ mice exhibit CMT-like phenotypes including thin and/or loose myelin, increased small-caliber axons, and disorganized axo-glial interactions. Heterozygous mice show a milder phenotype. These results highlight the importance of an appropriate L-MPZ/P0 ratio and show that aberrant readthrough of a myelin protein causes neuropathy.

Efficient gene therapy with a combination of ultrasound­targeted microbubble destruction and PEI/DNA/NLS complexes.

Current strategies of gene transfection are not efficient at achieving a notable therapeutic effect. The aim of the present study was to combine ultrasound­targeted microbubble destruction (UTMD) with a polyethylenimine/pEGFP­N3 plasmid/nuclear localization sequence (PEI/DNA/NLS) complex gene delivery system, and evaluate the transfection efficiency of enhanced green fluorescent protein (EGFP) gene delivery to 293T cells using this system. The formation of PEI/DNA/NLS complexes and the protective effects of PEI/NLS were verified by gel electrophoresis. Solutions consisting of the plasmid alone, PEI/DNA complexes, PEI/DNA/NLS complexes, UTMD+DNA, UTMD+PEI/DNA complexes, and UTMD+PEI/DNA/NLS complexes were transduced into 293T cells via ultrasound irradiation. The expression of GFP was observed using an inverted microscope and transfection efficiency was detected by flow cytometry following 24 h incubation in vitro. Cell activity was detected using a Cell Counting kit (CCK)­8 assay. Gel electrophoresis confirmed the formation of PEI/DNA/NLS complexes and demonstrated that PEI/NLS exhibited protective effects on plasmid integrity for a limited time. Inverted microscope observations revealed that a greater GFP signal was observed with the combined action of PEI/DNA/NLS complexes with UTMD, and flow cytometry analysis demonstrated the highest level of transfection efficiency in this group. In addition, the viability of the cells detected by CCK­8 and treated with PEI/DNA/NLS complexes with UTMD was >80%. In conclusion, the combination of UTMD and PEI/DNA/NLS complexes was highly effective for the efficient transfection of 293T cells without causing excessive cell damage. This method may provide a novel and effective gene transduction system to be applied in clinical treatments.