Systematics of Mukdenia and Oresitrophe (Saxifragaceae): Insights from genome skimming data

Oresitrophe and Mukdenia (Saxifragaceae) are epilithic sister genera used in traditional Chinese medicine. The taxonomy of Mukdenia, especially of M. acanthifolia, has been controversial. To address this, we produced plastid and mitochondrial data using genome skimming for Mukdenia acanthifolia and Mukdenia rossii, including three individuals of each species. We assembled complete plastomes, mitochondrial CDS and nuclear ribosomal ETS/ITS sequences using these data. Comparative analysis shows that the plastomes of Mukdenia and Oresitrophe are relatively conservative in terms of genome size, structure, gene content, RNA editing sites and codon usage. Five plastid regions that represent hotspots of change (trnH-psbA, psbC-trnS, trnM-atpE, petA-psbJ and ccsA-ndhD) are identified within Mukdenia, and six regions (trnH-psbA, petN-psbM, trnM-atpE, rps16-trnQ, ycf1 and ndhF) contain a higher number of species-specific parsimony-informative sites that may serve as potential DNA barcodes for species identification. To infer phylogenetic relationships between Mukdenia and Oresitrophe, we combined our data with published data based on three different datasets. The monophyly of each species (Oresitrophe rupifraga, M. acanthifolia and M. rossii) and the inferred topology ((M. rossii, M. acanthifolia), O. rupifraga) are well supported in trees reconstructed using the complete plastome sequences, but M. acanthifolia and M. rossii did not form a separate clade in the trees based on ETS + ITS data, while the mitochondrial CDS trees are not well-resolved. We found low recovery of genes in the Angiosperms353 target enrichment panel from our unenriched genome skimming data. Hybridization or incomplete lineage sorting may be the cause of discordance between trees reconstructed from organellar and nuclear data. Considering its morphological distinctiveness and our molecular phylogenetic results, we strongly recommend that M. acanthifolia be treated as a distinct species.     

脏器微血管对荧光素钠通透性的实验方法

大鼠颈动脉注射１％ＦｌＮａ,荧光显微镜下活体观察肠系膜微血管血流状态及ＦｌＮａ的渗出情况,并在不同时间点经股动脉采血,测定血浆内ＦｌＮａ浓度随时间的变化,利用组织匀浆测定不同脏器中ＦｌＮａ的分布,再辅以冰冻切片进行观察。活体观察发现,ＦｌＮａ注入体内后,经微血管迅速向周围组织渗出,最后汇集于淋巴管,血浆及组织匀浆ＦｌＮａ浓度的测定表明,ＦｌＮａ浓度随时间的变化呈指数衰减,各脏器ＦｌＮａ的分布极不相同。冰冻切片也显示了同样的分布差别。这些结果表明,我们所建立的方法可直观、定量地反映ＦｌＮａ在微血管的通透情况。     

人体超微弱发光图像中的信号检验

用近期研制的具有单光子探测能力的超高灵敏度成像系统获得了人体体表生物超微弱发光的强度数据。为分析图像中的信号检验,二项分布被用于人手不同时间累积发光图像中的信号显著性检验,证实人手存在超微弱生物发光,手指的发光强度在３００～５５０ｐｈｏｔｏｎｓ／ｓ范围内,全手的发光强度在８５０～１２００ｐｈｏｔｏｎｓ／ｓ范围内。     

高压静电场处理沙棘插条生根状况的初步研究

用高压静电场处理沙棘插条研究生根状况,方法简便易于处理,该装置适于进行大规模的处理,从目前研究表明：高压静电场对沙棘插条有正刺激效应,并以电场强度为３．９ｋｖ／ｃｍ,时间为４０分钟处理最佳。     

用细胞色素C法检测非真空电子束辐射的间接作用

本文提出了一种检测非真空电束辐射的间接作用的一种方法,根据氧化型和还原型的细胞色素Ｃ的吸收光谱不同,从而测量非真空电子束作用对应的辐射分解的自由基总量。     

Binding characterization of the iron transport receptor from the outer membrane of Escherichia coli (FepA): differentiation between FepA and FecA

The dissociation constants for the binding of ferric enterobactin with FepA and FecA are quantitated with displacement experiments. It is found that K _d for FepA is 12 times lower than the one for FecA. This indicates that FepA is an high-affinity receptor while FecA binds ferric enterobactin with a lower affinity. Monoclonal antibodies specific for binding epitopes of FepA inhibit the binding of ferric enterobactin with purified FepA. These same antibodies do not inhibit the binding of ferric enterobactin with purified FecA. This indicates that the binding epitopes in FecA and FepA are different.     

开启防御之门: 植物抗病小体

NLR蛋白是存在于植物和动物中的一个免疫受体大家族, 具有核苷酸结合域并富含亮氨酸重复序列。植物NLR通过识别病原菌特异效应子开启免疫信号转导。第1个植物NLR抗性蛋白于25年前克隆, 但其激活机制仍不清楚, 至今仍未获得一个完整的NLR蛋白结构。最近, 柴继杰、周俭民和王宏伟实验室合作解析了第一个植物完整NLR ZAR1激活前后的结构, 研究成果以两篇论文形式发表在“科学”杂志上, 填补了NLR介导的免疫信号转导研究领域的空白。该文简要总结了相关研究进展, 讨论了NLR免疫信号转导研究领域尚需解决的问题。     

肌钙蛋白C(Tropnin C)的提纯与鉴定

<正> 肌钙蛋白C(TnC)是肌钙蛋白复合体的钙结合亚基,系骨骼肌和心肌收缩系统的触发因子。研究表明TnC与钙调素(CaM)类似,具有EF手结构和四个特殊的钙结合区。TnC与Ca~(2+)、Mg~(2+)等金属离子的结合可发生构型变化及由此导致的体内一系列酶活性等生理功能的变化。提纯TnC是进行其诸方面研究的基础。