Developing a fluorescence substrate for HRP-based diagnostic assays with superiorities over the commercial ADHP

The combination of horseradish peroxidase(HRP)and a fluorescence substrate has been attracting great interests in developing sensitive biochemical analysis and immunoassays.10-Acetyl-3,7-dihydroxyphenoxazine(ADHP or Amplex red)is the most sensitive fluorogenic substrate known for HRP in current market,however,it suffers from some drawbacks,such as non-specific reactivity to carboxylesterase and limited fluorescence stability.In the present study,a novel HRP substrate10-cyclopropylcarbonyl-dichloro-dihydroxyphenoxazine(AR-2),has been prepared,which exhibited improved sensitivity than ADHP in sensing HRP.Moreover,the fluorescence of AR-2/HRP demonstrated improved tolerance to physiological relevant p H fluctuation as compared to ADHP/HRP.Successful detection of uric acid/urate oxidase reaction indicated excellent application prospect of AR-2/HRP for monitoring H_(2)O_(2)-generating biochemical reactions.More interestingly,an enzyme-linked immunosorbent assay(ELISA)using AR-2 as the fluorescence reporter has been successfully used in detecting IgG against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)from human serum samples.Overall,AR-2 exhibits improved performances over the commercial ADHP,which will be an ideal alternative to ADHP in HRP-based fluorescence biochemical analysis and immunoassays.

HOXA9、CRIP2互相作用抑制HIF-1α介导的糖酵解以阻遏皮肤鳞癌发生发展

皮肤鳞状细胞癌（cutaneous squamous cell carcinoma，cSCC，简称皮肤鳞癌）是全球范围内发病率排名第二的癌症，其恶性程度高、转移能力强，5年生存期只有22％～56％，每年新发病例超过100万。过量紫外辐射暴露是诱发皮肤鳞癌的首要环境因素，亟需深入了解紫外线诱发皮肤鳞癌的分子机制、并有针对性地开发有效的皮肤鳞癌新疗法。低氧诱导因子HIF-1α对紫外辐射敏感，其表达水平与与皮肤鳞癌细胞增殖和糖酵解代谢水平密切相关，并与皮肤鳞癌分级呈正相关，但之前的研究并未揭示其调控机制。

Transgenic expression of MYB15 confers enhanced sensitivity to abscisic acid and improved drought tolerance in Arabidopsis thaliana

Abiotic stresses cause serious crop losses. Knowledge on genes functioning in plant responses to adverse growth conditions is essential for developing stress tolerant crops. Here we report that transgenic expression of MYB15, encoding a R2R3 MYB transcription factor in Arabidopsis thaliana, conferred hypersensitivity to exogenous abscisic acid （ABA） and improved tolerance to drought and salt stresses. The promoter of MYB15 was active in not only vegetative and reproductive organs but also the guard cells of stomata. Its transcript level was substantially upregulated by ABA, drought or salt treatments. Compared with wild type （WT） control, MYB15 overexpression lines were hypersensitive to ABA in germination assays, more susceptible to ABA-elicited inhibition of root elongation, and more sensitive to ABA-induced stomatal closure. In line with the above findings, the transcript levels of ABA biosynthesis （ABA1, ABA2）, signaling （AB13） and responsive genes （AtADH1, RD22, RD29B, AtEM6） were generally higher in MYB15 overexpression seedlings than in WT controls after treatment with ABA. MYB15 overexpression lines displayed improved survival and reduced water loss rates than WT control under water deficiency conditions. These overexpression lines also displayed higher tolerance to NaCI stress. Collectively, our data suggest that overexpression of MYB15 improves drought and salt tolerance in Arabidopsis possibly by enhancing the expression levels of the genes involved in ABA biosynthesis and signaling, and those encoding the stress-protective proteins.

Methylmercury and sulfate-reducing bacteria in mangrove sediments from Jiulong River Estuary,China

Estuaries are important sites for mercury （Hg） methylation, with sulfate-reducing bacteria （SRB） thought to be the main Hg methylators. Distributions of total mercury （THg） and methylmercury （MeHg） in mangrove sediment and sediment core from Jiulong River Estuary Provincial Mangrove Reserve, China were determined and the possible mechanisms of Hg methylation and their controlling factors in mangrove sediments were investigated. Microbiological and geochemical parameters were also determined. Results showed that SRB constitute a small fraction of total bacteria （TB） in both surface sediments and the profile of sediments. The content of THg, MeHg, TB, and SRB were （350 ± 150） ng/g, （0.47 ± 0.11） ng/g, （1.4× 10^011 ± 4.1 × 10^9） cfu/g dry weight （dw）, and （5.0× 10^6 d： 2.7 × 10^6） cfu/g dw in surficial sediments, respectively, and （240 ± 24） ng/g, （0.30 ± 0.15） ng/g, （1.9 × 10^11 ± 4.2 × 10^9） cfu/g dw, and （1.3 × 10^6 ± 2.0 × 10^6） cfu/g dw in sediment core, respectively. Results showed that THg, MeHg, TB, MeHg/THg, salinity and total sulfur （TS） increased with depth, but total organic matter （TOM）, SRB, and pH decreased with depth. Concentrations of MeHg in sediments showed significant positive correlation with THg, salinity, TS, and MeHg/THg, and significant negative correlation with SRB, TOM, and pH. It was concluded that other microbes, rather than SRB, may also act as main Hg methylators in mangrove sediments.

Study on the influence of fracture lengths and fracture angles on residual oil distribution based on the slab model

After fracturing in the pilot area,channeling occurs at a low fracture angle(15).Based on the resistance-water saturation relationship,three-dimensional physical simulation methods are used in the laboratory to study the effect of different fracture angles and lengths on the residual oil distribution during the displacement process.Meanwhile,recovery percent,displacement efficiency and expanding sweep co-efficient to the improvement of recovery percent are also discussed.The results show that the fracture angle and length are closely related to the oil saturation distribution in these models.As the fracture angle increases,the sweep coefficient decreases(0.2412→0.1463),and the recovery percent also in-creases(46.16→56.88%),but the extent of increase has been reduced(7.96→2.96%).The extension of the fracture length is more prone to have a cross-flow phenomenon;the sweep coefficient is reduced(0.2412→0.1463).Compared to the model with 1/2 oil-water well spacing,the recovery percent is decreased by 14.29%.In different fracture models,the increasable sweep coefficient has a greater impact on oil recovery than the increasable displacement efficiency(71.30→28.70%).