HIF‐1α forms regulatory loop with YAP to coordinate hypoxia‐induced adriamycin resistance in acute myeloid leukemia cells

Despite the improvement in acute myeloid leukemia (AML) treatments, most patients had a poor prognosis and suffered from chemoresistance and disease relapse. Therefore, there is an urgent need for elucidation of mechanism(s) underlying drug resistance in AML. In the present study, we found that AML cells showed less susceptibility to adriamycin (ADR) in the presence of hypoxia, while inhibition of hypoxia‐inducible factor 1α (HIF‐1α) by CdCl₂ can make AML cells re‐susceptibile to ADR even under hypoxia. Moreover, HIF‐1α is overexpressed and plays an important role in ADR‐resistance maintenance in resistant AML cells. We further found hypoxia or induction of HIF‐1α can significantly upregulate yes‐associated protein (YAP) expression in AML cells, and resistant cells express a high level of YAP. Finally, we found that YAP may not only enhance HIF‐1α stability but also promote HIF‐1α's activity on the target gene pyruvate kinase M2. In conclusion, our data indicate that HIF‐1α or YAP may represent a therapeutic target for overcoming resistance toward adriamycin‐based chemotherapy in AML.     

Permeabilized Escherichia coli Whole Cells Containing Co‐Expressed Two Thermophilic Enzymes Facilitate the Synthesis of scyllo‐Inositol from myo‐Inositol

Scyllo‐inositol (SI), a stereoisomer of inositol, is regarded as a promising therapeutic agent for Alzheimer's disease. Here, an in vitro cofactor‐balance biotransformation for the production of SI from myo‐inositol (MI) by thermophilic myo‐inositol 2‐dehydrogenase (IDH) and scyllo‐inositol 2‐dehydrogenase (SIDH) is presented. These two enzymes (i.e., IDH and SIDH from Geobacillus kaustophilus) are co‐expressed in Escherichia coli BL21(DE3), and E. coli cells containing the two enzymes are permeabilized by heat treatment as whole‐cell catalysts to convert MI to SI. After condition optimizations about permeabilized temperature, reaction temperature, and initial MI concentration, about 82 g L^?1 of SI is produced from 250 g L^?1 of MI within 24 h without any cofactor supplementation. This final titer of SI produced is the highest to the authors’ limited knowledge. This study provides a promising method for the large‐scale industrial production of SI.     

Sl‐lncRNA15492 interacts with Sl‐miR482a and affects Solanum lycopersicum immunity against Phytophthora infestans

Long non‐coding RNAs (lncRNAs) are involved in the resistance of plants to infection by pathogens via interactions with microRNAs (miRNAs). Long non‐coding RNAs are cleaved by miRNAs to produce phased small interfering RNAs (phasiRNAs), which, as competing endogenous RNAs (ceRNAs), function as decoys for mature miRNAs, thus inhibiting their expression, and contain pre‐miRNA sequences to produce mature miRNAs. However, whether lncRNAs and miRNAs mediate other molecular mechanisms during plant resistance to pathogens is unknown. In this study, as a positive regulator, Sl‐lncRNA15492 from tomato (Solanum lycopersicum Zaofen No. 2) plants affected tomato resistance to Phytophthora infestans. Gain‐ and loss‐of‐function experiments and RNA ligase‐mediated 5′‐amplification of cDNA ends (RLM‐5′ RACE) also revealed that Sl‐miR482a was negatively involved in tomato resistance by targeting Sl‐NBS‐LRR genes and that silencing of Sl‐NBS‐LRR1 decreased tomato resistance. Sl‐lncRNA15492 inhibited the expression of mature Sl‐miR482a, whose precursor was located within the antisense sequence of Sl‐lncRNA15492. Further degradome analysis and additional RLM‐5′ RACE experiments verified that mature Sl‐miR482a could also cleave Sl‐lncRNA15492. These results provide a mechanism by which lncRNAs might inhibit precursor miRNA expression through antisense strands of lncRNAs, and demonstrate that Sl‐lncRNA15492 and Sl‐miR482a mutually inhibit the maintenance of Sl‐NBS‐LRR1 homeostasis during tomato resistance to P. infestans.     

重组枯草芽孢杆菌全细胞催化合成2-O-α-D-甘油葡糖苷

2-O-α-D-甘油葡糖苷是一种在食品、化妆品、保健品及医药领域有着重大应用前景的高附加值产品,但国内仍未实现2-O-α-D-甘油葡糖苷的工业化生产,且鲜有关于2-O-α-D-甘油葡糖苷合成的相关报道。文中旨在开发一种利用食品安全级重组枯草芽孢杆菌全细胞催化合成2-O-α-D-甘油葡糖苷的方法,通过构建一株异源表达肠膜明串珠菌蔗糖磷酸化酶 (Sucrose phosphorylase,SPase) 的重组枯草芽孢杆菌Bacillus subtilis 168/pMA5-gtfA,并将其用作全细胞催化剂合成2-O-α-D-甘油葡糖苷,通过优化培养温度、时间及全细胞转化条件,提高其转化合成2-O-α-D-甘油葡糖苷的产量。结果表明,重组枯草芽孢杆菌B. subtilis 168/pMA5-gtfA在30 ℃下培养20 h,菌体裂解物酶活力最大达1.43 U/mL,并且在1 mol/L蔗糖、2.5 mol/L甘油、pH 7.0、菌体OD600为40、30 ℃下全细胞转化反应48 h,共生成2-O-α-D-甘油葡糖苷189.3 g/L,平均转化速率为15.6 mmol/(L·h),蔗糖转化率约为75.1%,是目前报道的利用重组枯草芽孢杆菌催化合成2-O-α-D-甘油葡糖苷的最高产量,这为2-O-α-D-甘油葡糖苷的工业化生产及应用奠定了理论和实验基础。     

三江平原七星河流域湿地植物多样性及影响因素

湿地植物多样性是生物多样性的重要组成部分,在维护湿地生态功能和湿地生态系统稳定性方面发挥着极其重要的作用。为研究七星河流域湿地植物的多样性,选择七星河流域的七星河国家级自然保护区和三环泡国家级自然保护区,分别于2016年和2017年,对该流域内湿地植物进行了实地植物样方调查,共计调查194个样方,利用TWINSPAN进行了样方群落划分,并采用广义线性模型分析了影响植物多样性的影响因素。结果表明七星河流域湿地植物共有532种,隶属于80科,212属,主要群落类型为湿苔草-隐果苔草群丛;狭叶甜茅群丛;萍蓬草-狐尾藻群丛;漂筏苔草群丛;小叶章-臌囊苔草群丛;甜茅-芦苇群丛;芦苇群丛;貉藻群丛等,狭叶甜茅群丛物种多样性较单一,芦苇群丛的物种多样性较丰富。广义线性模型分析结果得出物种多样性与植被密度密切相关,植被密度越大,物种的多样性越小。为七星河流域物种多样性研究提供了重要的基础数据。     

云南松三种同域共存切梢小蠹梢转干期的空间分布格局

分布在我国西南地区的横坑切梢小蠹,云南切梢小蠹和短毛切梢小蠹同域危害寄主云南松,给林业生产带来巨大损失。为探讨同域切梢小蠹种群在共存下对其空间分布格局的影响,采用传统聚集指标法和地统计学方法研究了三者在梢转干期不同受害云南松纯林树冠中的空间分布型。结果表明重度受害样地中云南切梢小蠹种群密度显著高于横坑切梢小蠹,在轻度受害样地则相反;传统聚集指标法结果显示同域共存的3种切梢小蠹种群在不同受害程度云南松中均为聚集分布,横坑切梢小蠹和云南切梢小蠹聚集是由环境因素和昆虫本身的聚集习性引起;地统计学结果表明除重度受害样地中短毛切梢小蠹呈随机分布外,其余切梢小蠹在不同种群密度下均呈聚集分布;除重度受害样地横坑切梢小蠹外,其他小蠹的空间依赖范围为4.01—7.45 m。横坑切梢小蠹和云南切梢小蠹在不同受害林分中拟合的半变异函数模型在球形模型和高斯模型之间转换。同域共存关系不影响不同种群密度下的切梢小蠹种群空间分布类型,但影响其半变异函数模型和理论参数。     

微花蛛毛苣苔在中国云南的发现及其补充描述

中越边境喀斯特地区是全球生物多样性热点地区,也是生物多样性保护的关键区域,近年来在该地区发现了多个蛛毛苣苔属植物的新种。微花蛛毛苣苔于2001年在越南北部喀斯特地区首次采集到标本,直到2018年才被发表出来,由于发表时仅基于一号花发育未成熟的标本,所以该物种的诸多形态特征仍不清楚。作者开展中越边境喀斯特地区植物多样性调查时,在我国云南东南部发现了微花蛛毛苣苔,并采集到花发育成熟的植株,对其进行了解剖观察和测量,现对该物种进行补充描述,并提供墨线图和野外生态照片以资辨认。微花蛛毛苣苔与腺花蛛毛苣苔在光滑无毛而反折的花萼以及被腺毛的花冠等形态上最相似,但不同之处在于微花蛛毛苣苔的叶上面幼时被褐色蛛丝状绵毛,后变近无毛,花序顶生,花冠长9～12 mm,蒴果直,不旋扭,长1.2～2.8 cm。微花蛛毛苣苔在滇东南的发现,说明中国南部喀斯特地区和越南北部喀斯特地区构成了一个完整的植物区系地理单元。     

限制性内切酶Mlu I蛋白及其硒代衍生物的制备

【背景】限制性内切酶Mlu I是一种常用的工具酶,在分子生物学领域发挥着重要的作用,其三维结构尚未被解析。【目的】在大肠杆菌中克隆表达、纯化重组Mlu I蛋白及其硒代蛋白,并进行结晶条件的研究。【方法】构建重组表达载体pET28b-Mlu I,在大肠杆菌BL21(DE3)pLysS中诱导表达,利用亲和层析和凝胶过滤层析纯化重组Mlu I蛋白和硒代Mlu I蛋白。对蛋白进行质谱检测、圆二色谱检测以及酶活检测,利用坐滴法进行结晶条件的筛选。【结果】构建了重组表达载体pET28b-Mlu I并纯化获得达到结晶纯度的蛋白,通过质谱检测确定硒代Mlu I蛋白中的8个甲硫氨酸全部被取代,结合酶活测试及圆二色谱检测确定了硒代对Mlu I蛋白的活性、结构无明显影响。采用坐滴法进行初步的晶体生长研究,重组蛋白目前已在1种条件下获得针状晶体并进行初步衍射,获得分辨率在0.32 nm左右的衍射数据。【结论】Mlu I蛋白及硒代Mlu I蛋白纯化体系的构建和结晶条件的研究,可为下一步解析Mlu I三维结构、作用机制的探讨及定向改造奠定基础。