Food-Grade Expression and Characterization of a Dextranase from Chaetomium gracile Suitable for Sugarcane Juice Clarification

The microbial production of dextranase using cheap carbon sources is beneficial to solve the economic loss caused by the accumulation of dextran in syrup. A food-grade microbial cell factory was constructed by introducing the dextranase encoding gene DEX from Chaetomium gracile to the chromosome of Bacillus subtilis, and the antibiotic resistance marker gene was subsequently deleted via the Cre/loxP strategy. The dual-promoter system with a sequentially arranged constitutive P43 promoter resulted in an 85 % increase in DEX expression. Under the optimal fermentation conditions of 10 g/L maltose, 15 g/L casein, 1 g/L Na₂HPO₄, 1 g/L FeSO₄ and 8 g/L NaCl, DEX activity was increased from 2.625 to 64.34 U/mL. Recombinant DEX was purified 5.98-fold with a recovery ratio of 26.67 % and specific activity of 3935.02 U/mg. Enzyme activity was optimal at 55 °C and pH 5.0 and remained 80.34 % and 71.36 % of the initial activity at 55 °C and pH 4.0 after 60 min, respectively. The enzyme possessed high activity in the presence of Co²⁺, while Ag⁺ showed the strongest inhibition ability. The optimal substrate was 20 g/L dextran T-2000. The findings could facilitate the low-cost, large-scale production of food-grade DEX for use in the sugar industry.     

A single nucleotide mutation in GID1c disrupts its interaction with DELLA1 and causes a GA‐insensitive dwarf phenotype in peach

Plant stature is one important factor that affects the productivity of peach orchards. However, little is known about the molecular mechanism(s) underlying the dwarf phenotype of peach tree. Here, we report a dwarfing mechanism in the peach cv. FenHuaShouXingTao (FHSXT). The dwarf phenotype of ‘FHSXT’ was caused by shorter cell length compared to the standard cv. QiuMiHong (QMH). ‘FHSXT’ contained higher endogenous GA levels than did ‘QMH’ and did not response to exogenous GA treatment (internode elongation). These results indicated that ‘FHSXT’ is a GA‐insensitive dwarf mutant. A dwarf phenotype‐related single nucleotide mutation in the gibberellic acid receptor GID1 was identified in ‘FHSXT’ (GID1c^S191F), which was also cosegregated with dwarf phenotype in 30 tested cultivars. GID1c^S191F was unable to interact with the growth‐repressor DELLA1 even in the presence of GA. ‘FHSXT’ accumulated a higher level of DELLA1, the degradation of which is normally induced by its interaction with GID1. The DELLA1 protein level was almost undetectable in ‘QMH’, but not reduced in ‘FHSXT’ after GA₃ treatment. Our results suggested that a nonsynonymous single nucleotide mutation in GID1c disrupts its interaction with DELLA1 resulting in a GA‐insensitive dwarf phenotype in peach.     

植物激素和接种方式对广西金线莲壮苗生根的影响

该文以广西野生金线莲无菌播种离体茎段为材料,采用单因素对比试验,研究了植物激素(NAA、IBA、6-BA、GA_3、KT、ZT、TDZ、2-IP)以及接种方式(竖直接种和水平接种)对壮苗生根培养的影响。结果表明:与对照相比,生长素有利于壮苗生根,NAA的效果优于IBA;细胞分裂素对壮苗生根的效果依次为6-BATDZKT=ZT 2-IPCK,其中6-BA诱导平均株高8.4 cm,3.6条根,茎粗为2.84 mm,植株生长健壮,诱导效果最好;赤霉素GA_3诱导出的植株高且直,但植株细弱,且抑制根系生长,不利于壮苗生根培养;在激素组合6-BA 0.5 mg·L~(-1)、NAA1.0 mg·L~(-1)处理中,组培苗生长健壮且根数量较多,效果最佳;水平接种能诱导出更多的根系,且便于接种操作,可以节省接种时间。因此,确定广西金线莲最适宜的壮苗生根培养基配方为1/2MS+6-BA 0.5 mg·L~(-1)+NAA 1.0 mg·L~(-1)+香蕉汁100 g·L~(-1)+AC(活性炭) 1.0 g·L~(-1)+蔗糖20 g·L~(-1),最佳接种方式为水平接种。     

GA3和Spd对杜鹃开花期光合特性和抗氧化系统的影响

为探讨GA_3和Spd对杜鹃(Rhododendron simsii)开花花期和开花品质的影响,研究了外源GA_3和Spd对杜鹃开花期光合特性和抗氧化系统的变化。结果表明,外源GA_3对花期有显著的提前作用,Spd对花期有明显的延迟作用,但两者均使花期延长、花径增大且成花率提高。GA_3和Spd处理提高了花期叶片的光合色素含量和净光合速率(Pn)、气孔导度(Gs)和胞间CO_2浓度(Ci);GA_3处理提高了叶片的蒸腾速率(Tr),而Spd使叶片的Tr下降,两者均有效缓解了末花期叶绿素含量的下降。GA_3和Spd处理显著降低了花瓣MDA含量,提高了抗氧化酶SOD、POD和CAT活性,并减缓了末花期SOD的下降,有效延缓了衰老进程,延长花期。以1 600 mg L~(–1) GA_3和0.10 mmol L~(-1) Spd处理效果较好,能有效提高杜鹃花的观赏品质。     

公众对园林绿地功能的认知及其对环境教育的启示——以广州市为例

以网络问卷和现场问卷、访谈的形式,分析公众对广州市园林绿地功能的认知情况,以期为环境教育场地的建设提供参考。结果显示,公众对于物种多样性和景观多样性的各项具体描述的认知情况都趋于一致,绝大多数公众认为绿地植被能发挥重要的生态功能,且公众的学历越高,其认知园林植物的欲望越强烈。在休息时,大多数公众会选择植物比较茂密的半开敞空间;在园林设计中通过增强科普信息获取的便利性和趣味性,能更好地发挥绿地的环境教育功能。     

Sensitive detection of sodium cromoglycate with glutathione‐capped CdTe quantum dots as a novel fluorescence probe

A sensitive and simple analytical strategy for the detection of sodium cromoglycate (SCG) has been established based on a readily detectable fluorescence quenching effect of SCG for glutathione‐capped (GSH‐capped) CdTe quantum dots (QDs). The fluorescence of GSH‐capped CdTe QDs could be efficiently quenched by SCG through electron transfer from GSH‐capped CdTe QDs to SCG. Under optimum conditions, the response was linearly proportional to the concentration of SCG between 0.6419 and 100 µg/mL, with a correlation coefficient (R) of 0.9964; the detection limit (3δ/K) was 0.1926 µg/mL. The optimum conditions and the influence of coexisting foreign substances on the reaction were also investigated. The very effective and simple method reported here has been successfully applied to the determination of SCG in synthetic and real samples. It is believed that the established approach could have good prospects for application in the fields of clinical diseases diagnosis and treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

Validation of Ten Noninvasive Diagnostic Models for Prediction of Liver Fibrosis in Patients with Chronic Hepatitis B

Background and Aims

Noninvasive models have been developed for fibrosis assessment in patients with chronic hepatitis B. However, the sensitivity, specificity and diagnostic accuracy in evaluating liver fibrosis of these methods have not been validated and compared in the same group of patients. The aim of this study was to verify the diagnostic performance and reproducibility of ten reported noninvasive models in a large cohort of Asian CHB patients.

Methods

The diagnostic performance of ten noninvasive models (HALF index, FibroScan, S index, Zeng model, Youyi model, Hui model, APAG, APRI, FIB-4 and FibroTest) was assessed against the liver histology by ROC curve analysis in CHB patients. The reproducibility of the ten models were evaluated by recalculating the diagnostic values at the given cut-off values defined by the original studies.

Results

Six models (HALF index, FibroScan, Zeng model, Youyi model, S index and FibroTest) had AUROCs higher than 0.70 in predicting any fibrosis stage and 2 of them had best diagnostic performance with AUROCs to predict F≥2, F≥3 and F4 being 0.83, 0.89 and 0.89 for HALF index, 0.82, 0.87 and 0.87 for FibroScan, respectively. Four models (HALF index, FibroScan, Zeng model and Youyi model) showed good diagnostic values at given cut-offs.

Conclusions

HALF index, FibroScan, Zeng model, Youyi model, S index and FibroTest show a good diagnostic performance and all of them, except S index and FibroTest, have good reproducibility for evaluating liver fibrosis in CHB patients.

Registration Number

ChiCTR-DCS-07000039.     

肺腺癌组织中表皮生长因子受体基因突变的检测及其临床意义

目的:通过检测肺腺癌组织中表皮生长因子受体(EGFR)基因的突变情况,研究EGFR突变与患者临床特征(性别、年龄和吸烟史)的相关性。方法:收集160例肺腺癌患者术前的石蜡组织标本,提取DNA后用实时定量PCR方法对EGFR基因18~21外显子进行突变检测;对基因突变结果与患者的性别、年龄和吸烟史分别做χ2检验。结果:160例肺腺癌组织标本中,有57例检测到EGFR基因突变,突变率为35.6%,且突变与患者性别、年龄和吸烟史均无显著相关性(P0.05);57例EGFR基因突变标本中,27例为19外显子缺失,22例为21外显子L858R点突变,这2种突变占总突变类型的85.96%,并且与患者性别、年龄及吸烟史无显著相关性(P0.05)。结论:EGFR基因在女性不吸烟肺腺癌中有较高的突变率,突变主要集中在19外显子缺失和21外显子L858R点突变,但突变率及突变类型与患者性别、年龄和吸烟史均不相关。     

Chiral Recognition of Tyrosine Enantiomers Based on Decreased Resonance Scattering Signals With Silver Nanoparticles as Optical Sensor

A novel chiral sensing platform, employing silver nanoparticles capped with N‐acetyl‐L‐cysteine (NALC‐Ag NPs), was utilized for the discrimination of L‐tyrosine and D‐tyrosine. This nanosensor, which could be used as an optical sensing unit and chiral probe, was characterized by transmission electron microscopy (TEM) and resonance Rayleigh scattering (RRS) spectroscopy. After the proposed sensing platform interacted with L‐tyrosine and D‐tyrosine, a decreased resonance scattering signal was only obtained from L‐tyrosine. This phenomenon offered a useful assay for the selectivity and determination of L‐tyrosine with the RRS method. The linear range and detection limit of L‐tyrosine were 0.2838–20.0 µg⋅mL^‐1 and 0.0860 µg⋅mL^‐1, respectively. In addition, experimental factors such as acidity, interaction time, and the concentration of enantiomers were investigated with regard to the effect on enantioselective interaction. Chirality 27:194–198, 2015. © 2014 Wiley Periodicals, Inc.     

视觉功能训练联合托吡卡胺滴眼液治疗假性近视的临床疗效观察

摘要 目的：探讨视觉功能训练联合托吡卡胺滴眼液在治疗假性近视中的临床疗效。方法：选取中国人民解放军陆军特色医学中心眼科和重庆佑佑宝贝妇儿医院眼科2019年2月至2019年8月收治的400例假性近视患儿作为研究对象,将其随机分为对照组和观察组(n=200)。对照组给予滴眼液缓解眼疲劳治疗,观察组则采用视觉功能训练联合托吡卡胺滴眼液治疗。比较两组患儿治疗前及治疗2个月、6个月后裸眼视力、眼轴长度、屈光度、正相对调节量和视疲劳评分的变化。结果：治疗2个月和6个月后,观察组患儿裸眼视力分别为(0.75±0.05)和(0.81±0.04),较对照组显著上升(P<0.05);屈光度分别为(+0.05±0.50)和(+0.06±0.48),明显高于对照组(P<0.05);正相对调节量检测结果依次是(-1.98±0.07)和(-2.51±0.24),较对照组明显增加(P<0.05)。两组患儿视觉感知双眼视功能均有明显改善,其中观察组视觉功能恢复显著高于对照组(P<0.05)。视疲劳调查显示观察组患儿视疲劳评分分别为(6.90±0.89)分和(3.91±0.89)分,显著低于对照组(P<0.05)。结论：视觉功能训练联合托吡卡胺滴眼液治疗能有效提高患儿裸眼视力、改善屈光度、正相对调节量和视觉感知功能,从而减少视疲劳,预防近视。