Function and solution structure of Huwentoxin-X, a specific blocker of N-type calcium channels, from the Chinese bird spider Ornithoctonus huwena

Huwentoxin-X (HWTX-X) is a novel peptide toxin, purified from the venom of the spider Ornithoctonus huwena. It comprises 28 amino acid residues including six cysteine residues as disulfide bridges linked in the pattern of I-IV, II-V, and III-VI. Its cDNA, determined by rapid amplification of 3' and 5' cDNA ends, encodes a 65-residue prepropeptide. HWTX-X shares low sequence homology with omega-conotoxins GVIA and MVIIA, two well known blockers of N-type Ca2+ channels. Nevertheless, whole cell studies indicate that it can block N-type Ca2+ channels in rat dorsal root ganglion cells (IC50 40 nm) and the blockage by HWTX-X is completely reversible. The rank order of specificity for N-type Ca2+ channels is GVIA approximately HWTX-X > MVIIA. In contrast to GVIA and MVIIA, HWTX-X had no detectable effect on the twitch response of rat vas deferens to low frequency electrical stimulation, indicating that HWTX-X has different selectivity for isoforms of N-type Ca2+ channels, compared with GVIA or MVIIA. A comparison of the structures of HWTX-X and GVIA reveals that they not only adopt a common structural motif (inhibitor cystine knot), but also have a similar functional motif, a binding surface formed by the critical residue Tyr, and several basic residues. However, the dissimilarities of their binding surfaces provide some insights into their different selectivities for isoforms of N-type Ca2+ channels.     

Genetic analysis of leaffolder resistance in rice

A double haploid(DH)population,which consists of 120 lines derived from anther culture of a typical indica and japonica hybrid'CJ06'/'TN1',was used to investigate the genetic basis for rice leaffolder resistance.Using a constructed molecular linkage map,five QTLs for rolled leaves were detected on chromosomes 1,2,3,4,and 8.The positive alleles from C J06 on chromosomes 3,4,and 8 in-creased the resistance to dee leaffolder,and the alleles from TN1 on chromosomes 1 and 2 also enhanced resistance to leaffolder.The interactions between QTLs were identified and tested,and four conditional interactions were acquired for resistance to rice leaffolder.These loci were located on chromosomes 2,9,10,and 11,respectively.QTL pyramiding indicated that the positive alleles affect resis-tance to leaffolder.The prospective application of this data in rice breeding was also discussed.     

人体动脉血气信号波浪式变化及连续动脉逐搏取血血气分析方法的建立*

目的: 建立动脉逐搏取血血气分析法,在人体实验中验证呼吸调控核心信号——PaO₂,PaCO₂和[H⁺]a是受呼吸影响的周期性、波浪式变化信号,而不是传统理念上误认的稳定水平信号。方法: 选择心功能正常、Allen试验阴性需要监测动脉血流动力学变化的患者6例。在左侧桡动脉穿刺,连接肝素化塑化管（3 mm×1 000 mm）,注满血液并计数血液注满所需心跳次数。用止血钳将塑化管钳闭成与心跳次数相对应的分段后,迅速置于冰水中,立即进行血气分析。选取每位患者的2个典型波浪式周期,用于分析2对最高-最低和最低-最高共4个测定值,取平均值。对相邻最高和最低值作统计学配对t检验。结果: 血液注满塑化管需要16±2次心跳,均覆盖超过2个呼吸周期。每个呼吸周期是5±0.6次心跳。PaO₂、PaCO₂、[H⁺]a和SaO₂都呈现出明显的波浪式变化（相邻高点与低点比较,P<0.05）,PaO₂、PaCO₂、[H⁺]a和SaO₂的波浪幅度分别是（11.28±1.13）mmHg,（1.77±0.89）mmHg,（1.14±0.35）nmol/L和（0.52±0.44）%;波浪幅度分别是其平均值的（7.7±1.1）%,（5.1±2.5）%,（3.1±1.0）%和（0.5±0.4）%。结论: 动脉延长管连续取血,按心跳次数分隔血样,血气分析法简单易行,为验证动脉血气受呼吸影响的周期性波浪式信号提供了可靠证据。本方法为原创,技术操作层面仍需提高熟练程度,增加志愿者和试验样本的数量进一步探索此类信号的临床检测可靠性及其与临床疾病的关系。     

地表火对红花尔基沙地樟子松种群空间分布格局的影响

利用全林木定位的方法, 对地表火干扰1年后的樟子松(Pinus sylvestris L. var. mongolica Litv.)林进行调查, 并通过假设检验和成对相关函数对其林火及林分结构特征和空间格局进行分析。结果表明, 林火强度相似的同一场地表火干扰下, 不同林分的密度均大大降低, 胸高断面积仅略有下降, 林分结构特征则有趋同的态势。不同林分的空间格局也有相似的变化趋势, 烧死木均表现为显著的双尺度聚集分布及显著的正相关, 活立木也表现出显著的正相关; 地表火干扰前后, 樟子松林的空间格局均为显著的聚集分布, 但地表火干扰后其聚集分布的尺度范围变小; 存活林木中, 大树和幼树则呈现出相互独立或略微排斥的关系。显然, 地表火驱动下, 不同樟子松林的空间格局呈现出相似的变化趋势, 并推动其向着成熟林方向演替, 这对天然樟子松林的资源保护和经营管理有着重要意义。     

中国森林生物量的估算：对Fang et al.

 Science杂志于2001年发表了方精云等人关于中国森林植被碳库及其变化的论文(Fang et al., 2001, 291: 2320～2322)。该文利用大量的生物量实测数据,结合使用中国50年来的森林资源清查资料及相关的统计资料,基于生物量换算因子连续函数法,研究了中国森林植被碳库及其时空变化。这是一个大时空尺度的工作,涉及一些大尺度生态学研究的原理、方法以及尺度转换问题。由于篇幅所限,论文并未详细说明这些问题。为了帮助理解大尺度生态学研究的方法和思路,本文给出了论文中涉及生物量计算的理论基础,对     

干旱与盐胁迫对花生根际土壤细菌群落结构和花生产量的影响

以花生品种花育25号为试验材料,采用盆栽试验研究了开花期干旱和盐分胁迫对花生生长发育和荚果产量的影响,并运用高通量测序技术分析干旱、盐胁迫及旱盐双重胁迫下,花生根际土壤细菌群落结构的变化特征。结果表明: 不同胁迫处理花生根际土壤细菌群落均以变形菌门、放线菌门、Saccharibacteria、绿弯菌门、蓝藻菌门和酸杆菌门为主。干旱、盐胁迫及旱盐双重胁迫均不同程度降低了变形菌门和放线菌门的相对丰度,但显著提高了蓝藻菌门的含量,且旱盐双重胁迫较其单一胁迫引起的根际蓝藻菌门丰度变化更显著。土壤细菌功能预测分析显示,信号转导机制、防御机制及翻译后修饰、蛋白质周转和分子伴侣等相关功能在旱盐双重胁迫的细菌中活性更强,可能对花生生长及胁迫应答具有重要影响。统计学分析显示,开花期干旱、盐胁迫和旱盐双重胁迫严重影响花生生长发育,并显著降低产量。研究结果可为通过改良土壤微生物环境来提高植物胁迫耐受性提供参考。     

编码锌指蛋白的人类新基因TFL76的电子克隆

目的：根据基因同源同功原理电子克隆人类新基因。方法：利用基于基因识别软件Genescan和EST拼接的同源基因克隆法得到人类新基因序列TFL76,再利用生物信息学数据库和软件对其进行功能的预测和分析。结果：TFL76的cDNA序列长2268bp,开放阅读框编码677个氨基酸残基,含12个连续的C2H2型锌指基序,其分子量为76kDa。编码区序列被4个内含子分割。染色体定位于19q13．4。此位点存在很多与胃癌、膀胱癌、乳腺癌等癌症相关的基因。TFL76的N末端含有多种蛋白激酶的磷酸化位点和核定位信号。结论：TFL76可能是一个和癌症相关的核转录因子。     

死皮对橡胶树树皮线粒体超微结构及活性氧代谢的影响

为了解析橡胶树（Hevea brasiliensis）死皮的发生机制,有效进行死皮防治,以健康、轻度死皮、重度死皮橡胶树树皮为材料,研究死皮发生过程中树皮线粒体超微结构变化规律及活性氧（ROS）相关基因的表达模式变化。结果表明：死皮树线粒体超微结构发生不规则形变,膜内基质溶解,嵴消失,内腔空泡化等,且严重程度与死皮严重程度成正比。荧光定量PCR结果表明,过氧化物酶基因HbPOD2和HbPOD3在死皮树中的表达量高于健康树,可作为监测割胶强度、刺激强度和死皮发生的“标志”基因。植物细胞重要ROS清除酶过氧化氢酶基因HbCAT在死皮树中也下调表达,预示ROS产生与清除之间的平衡是影响橡胶树死皮发生的关键因素。橡胶树中重要抗氧化代谢物基因表达结果表明,HbGST1、HbGST2和HbPPO在死皮树中的表达量均高于健康树,可能与死皮发生过程胶乳原位凝固相关。本研究通过揭示死皮发生过程树皮超微结构和ROS相关基因表达模式变化,为阐明橡胶树死皮发生机制提供新观点,同时为进一步开发监测割胶强度、刺激强度和死皮发生的基因“标志”提供理论基础。     

Integrated Machine Learning and Bioinformatic Analyses Constructed a Novel Stemness-Related Classifier to Predict Prognosis and Immunotherapy Responses for Hepatocellular Carcinoma Patients

Immunotherapy has made great progress in hepatocellular carcinoma (HCC), yet there is still a lack of biomarkers for predicting response to it. Cancer stem cells (CSCs) are the primary cause of the tumorigenesis, metastasis, and multi-drug resistance of HCC. This study aimed to propose a novel CSCs-related cluster of HCC to predict patients'' response to immunotherapy. Based on RNA-seq datasets from The Cancer Genome Atlas (TCGA) and Progenitor Cell Biology Consortium (PCBC), one-class logistic regression (OCLR) algorithm was applied to compute the stemness index (mRNAsi) of HCC patients. Unsupervised consensus clustering was performed to categorize HCC patients into two stemness subtypes which further proved to be a predictor of tumor immune microenvironment (TIME) status, immunogenomic expressions and sensitivity to neoadjuvant therapies. Finally, four machine learning algorithms (LASSO, RF, SVM-RFE and XGboost) were applied to distinguish different stemness subtypes. Thus, a five-hub-gene based classifier was constructed in TCGA and ICGC HCC datasets to predict patients'' stemness subtype in a more convenient and applicable way, and this novel stemness-based classification system could facilitate the prognostic prediction and guide clinical strategies of immunotherapy and targeted therapy in HCC.     

巢湖蓝藻与农业废弃物共热解制取生物质油研究

采用蔗渣、玉米秸秆和棉花秸秆3种废弃物与蓝藻进行混合共热解试验,考察废弃物的加入对蓝藻热解液体产率及组分的影响。结果表明:添加3种废弃物均使共热解液体产率呈下降趋势。当蓝藻与废弃物以1∶1混合共热解时,以蓝藻和玉米秸秆共热解液体产率最高,为61.8%,且除苯酚类以外,液体产物组分与单一蓝藻热解产物组分相近,含氮化合物含量明显降低,相对含量由18.49%降至8.15%。与其它2种废弃物相比,蓝藻与玉米秸秆在适当比例下的共热解有利于改善热解油品质。