Oat leaf base: tissue with an efficient regeneration capacity

Summary An efficient short term regeneration system using seedling derived oat (Avena sativa) leaf tissue has been developed. Callus derived from the leaf base showed a higher response of plant regeneration than callus initiated from mesocotyls and more mature parts of the leaves. A correlation between the nuclear DNA content of the donor material, as analysed with flow cytometry, and its ability to form callus was observed. Somatic embryogenesis was histologically recognised from callus derived from tissue close to the apical meristem. Plant regeneration media with various concentrations of auxin were tested. Callus from three different cultivars had a similar regeneration potential with an optimal regeneration frequency of 60%. About 2 months after inoculation regenerated plantlets could be moved to a greenhouse for cultivation.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - DAPI 6-diamidino-2-phenylindole - IAA indole-3-acetic acid - KT kinetin - MS Murashige and Skoog's medium - NAA naphthalene acetic acid     

湖羊瘤胃微生物GH9家族葡聚糖酶基因IDSGLUC9-25的表达与功能表征

【目的】葡聚糖酶是饲用添加剂的重要成分,本研究旨在从湖羊消化道微生物中挖掘性质优良的GH9家族葡聚糖酶基因,用于研发新型饲用酶制剂。【方法】从湖羊瘤胃微生物cDNA中扩增IDSGLUC9-25基因,在大肠杆菌中进行异源表达,对重组蛋白进行诱导表达和纯化,研究重组蛋白的酶学性质和底物水解模式。【结果】IDSGLUC9-25基因编码527个氨基酸,包含一个CelD_N结构和一个GH9家族催化结构域;重组蛋白rIDSGLUC9-25分子量约为62.7 kDa,最适反应温度和pH分别为40℃和6.0,在30-50℃下活性较高,在pH 4.0-8.0范围内能够保持较高的稳定性,经pH 4.0-8.0缓冲液处理1 h后残余活性均大于90%;底物谱分析表明,rIDSGLUC9-25能催化大麦β-葡聚糖、苔藓地衣多糖、魔芋胶和木葡聚糖,比活性分别为(443.55±24.48)、(65.56±5.98)、(122.37±2.85)和(159.16±7.73) U/mg;利用薄层色谱法(thin layer chromatography, TLC)和高效液相色谱法(high performance liquid chromatography, HPLC)分析水解产物发现,rIDSGLUC9-25降解大麦葡聚糖主要生成纤维三糖(占总还原糖64.19%±1.19%)和纤维四糖(占总还原糖26.24%±0.12%),催化地衣多糖主要生成纤维三糖(占总还原糖78.46%±0.89%)。【结论】本研究报道了一种来自密螺旋体属细菌的内切β-1,4-葡聚糖酶IDSGLUC9-25 (EC 3.2.1.4),能高效催化多糖底物生成纤维三糖和纤维四糖,为研发饲用酶制剂和制备低聚寡糖建立基础。     

TEB/POLQ plays dual roles in protecting Arabidopsis from NO-induced DNA damage

Nitric oxide (NO) is a key player in numerous physiological processes. Excessive NO induces DNA damage, but how plants respond to this damage remains unclear. We screened and identified an Arabidopsis NO hypersensitive mutant and found it to be allelic to TEBICHI/POLQ, encoding DNA polymerase θ. The teb mutant plants were preferentially sensitive to NO- and its derivative peroxynitrite-induced DNA damage and subsequent double-strand breaks (DSBs). Inactivation of TEB caused the accumulation of spontaneous DSBs largely attributed to endogenous NO and was synergistic to DSB repair pathway mutations with respect to growth. These effects were manifested in the presence of NO-inducing agents and relieved by NO scavengers. NO induced G2/M cell cycle arrest in the teb mutant, indicative of stalled replication forks. Genetic analyses indicate that Polθ is required for translesion DNA synthesis across NO-induced lesions, but not oxidation-induced lesions. Whole-genome sequencing revealed that Polθ bypasses NO-induced base adducts in an error-free manner and generates mutations characteristic of Polθ-mediated end joining. Our experimental data collectively suggests that Polθ plays dual roles in protecting plants from NO-induced DNA damage. Since Polθ is conserved in higher eukaryotes, mammalian Polθ may also be required for balancing NO physiological signaling and genotoxicity.     

Local Recurrence of Soft Tissue Sarcoma Revisited: Is there a Role for “Selective” Radiation?

BackgroundRadiation therapy (RT) is often utilized in cases of high-grade soft tissue sarcoma (STS), but there remain situations where treatment is with surgical excision alone. Our goals were to determine (1) the local recurrence (LR) rate with and without perioperative RT and (2) associations between local recurrence, patient, tumor, and treatment variables.MethodsWe performed a retrospective review of 165 consecutive STS patients. A Cox proportional hazards model was used to investigate variables associated with local recurrence.ResultsLR occurred in 15/78 (19%) without RT, 4/29 (14%) with postoperative RT, and 0/58 with preoperative RT (p=0.002). We found increased rates of local recurrence at 24 months for myxofibrosarcoma (p=0.001) and no-RT (p=0.003). Myxofibrosarcoma accounted for 33 (20%) of the study patients and 12 (63%) of the local recurrences.ConclusionThe LR rate in patients treated with surgery alone was disproportionately attributable to myxofibrosarcoma (11/23 cases, 48%). Other subtypes demonstrated a lower rate of LR in the absence of RT (4/55 cases, 7%), and no LR occurred when final margins were >2 mm. In certain circumstances treatment with a negative margin surgical resection followed by close observation is justifiable. RT is effective and should continue to be considered routinely in myxofibrosarcoma or when surgical margins are inadequate. Level of Evidence: III     

茉莉酸甲酯对烟草幼苗抗病毒的影响

用茉莉酸甲酯处理4叶期烟草(Nicotiana tabacum L.)幼苗后接种烟草花叶病毒,考察发病情况和病情指数,并测定一些与抗病相关的酶活性。结果表明,茉莉酸甲酯处理后接种病毒明显降低巴两烟草的病情指数,提高几丁内切酶、β1,3-葡聚糖苷酶、SOD、脂氧酶的活件。其中仅SOD活性与抗病毒有较密切的关系。茉莉酸甲酯可能是诱导巴西烟草抗花叶病毒的信号物质。     

Effects of size,neighbors, and site condition on tree growth in a subtropical evergreen and deciduous broad‐leaved mixed forest,China

Successful growth of a tree is the result of combined effects of biotic and abiotic factors. It is important to understand how biotic and abiotic factors affect changes in forest structure and dynamics under environmental fluctuations. In this study, we explored the effects of initial size [diameter at breast height (DBH)], neighborhood competition, and site condition on tree growth, based on a 3‐year monitoring of tree growth rate in a permanent plot (120 × 80 m) of montane Fagus engleriana–Cyclobalanopsis multiervis mixed forest on Mt. Shennongjia, China. We measured DBH increments every 6 months from October 2011 to October 2014 by field‐made dendrometers and calculated the mean annual growth rate over the 3 years for each individual tree. We also measured and calculated twelve soil properties and five topographic variables for 384 grids of 5 × 5 m. We defined two distance‐dependent neighborhood competition indices with and without considerations of phylogenetic relatedness between trees and tested for significant differences in growth rates among functional groups. On average, trees in this mixed montane forest grew 0.07 cm year^?1 in DBH. Deciduous, canopy, and early‐successional species grew faster than evergreen, small‐statured, and late‐successional species, respectively. Growth rates increased with initial DBH, but were not significantly related to neighborhood competition and site condition for overall trees. Phylogenetic relatedness between trees did not influence the neighborhood competition. Different factors were found to influence tree growth rates of different functional groups: Initial DBH was the dominant factor for all tree groups; neighborhood competition within 5 m radius decreased growth rates of evergreen trees; and site condition tended to be more related to growth rates of fast‐growing trees (deciduous, canopy, pioneer, and early‐successional species) than the slow‐growing trees (evergreen, understory, and late‐successional species).     

八角茴香油的提取及应用

本文综述了八角茴香油的主要成分、提取分离方法及在医药等方面的应用,为八角茴香油的进一步研究及应用提供参考。     

我国人轮状病毒不同基因型NSP4的致病性研究

对我国轮状病毒流行株NSP4基因变异特点的分析表明,NSP4基因主要可分为Wa组和Kun组,在Wa组内可形成三个亚组,形成了4种NSP4基因型.为了进一步阐明人轮状病毒流行株NSP4基因变异与其致病性变化是否存在联系,我们首先利用杆状病毒载体对NSP4蛋白进行表达,获得了对应4种不同NSP4基因型的重组杆状病毒rvBac97B6,rvBac97S34,rvBac97S36和rvBac97SZ8.用这些病毒感染Sf-9细胞后,检测细胞内Ca2+浓度的变化,发现与野生型杆状病毒感染细胞相比,重组病毒感染细胞内的Ca2+浓度显著升高,但各个重组病毒之间无显著性差异.在此基础上,我们进一步在E.coli中分别表达纯化了代表Wa和Kun基因分组的97S34和97SZ8流行株的NSP4.分别用纯化的重组NSP4蛋白攻击乳鼠后,发现不同基因型的NSP4蛋白的致腹泻活性没有明显差异,这种作用可被NSP4抗体拮抗,但这种拮抗作用存在基因型特异性.上述结果表明人轮状病毒流行株NSP4氨基酸序列间的变异并没有使其钙调节及致腹泻能力产生改变,在致腹泻作用中发挥关键作用(或决定性作用)的氨基酸位点在不同NSP4基因型间可能是相对保守的.针对NSP4抗体的有效性也为新型轮状病毒疫苗和药物研究提供了线索.     

上海市首例输入性甲型H1N1流行性感冒报道

甲型H1N1流行性感冒(简称流感)是由一种新型流感病毒引起的急性呼吸道传染性疾病。临床主要表现为流感样症状,包括发热、流涕、咽痛、咳嗽、头痛、腹泻等。奥司他韦和扎那米韦治疗甲型H1N1流感有效。本文报道上海市首例输入性甲型H1N1流感病例,以提高临床医生对这种新发流感的认识。     

Wnt/β-catenin信号通路在博来霉素诱导的系统性硬化症小鼠模型血管重塑中的作用

系统性硬化症(systemic sclerosis,SSc)是一种慢性可累及全身多脏器的自身免疫性疾病,以广泛的血管病变及皮肤和内脏的纤维化为特征,但其机制迄今尚不明确。已有研究证实,Wnt通路参与了SSc纤维化,但其在血管病变中的病理作用尚未见报道。本研究拟采用博来霉素(bleomycin,BLM)诱导的SSc小鼠模型,探讨Wnt通路在SSc皮肤血管病变中的作用。将18只Balb/C小鼠随机平均分为3组,分别设为对照组(于小鼠背部皮下注射PBS 100 μL/d)、模型组(于小鼠背部皮下注射浓度为 1 mg/mL 博来霉素BLM 100 μL/d)和治疗组(于小鼠背部皮下注射 1 mg/mL BLM 100 μL/d,同时腹腔注射Wnt及β-catenin的抑制剂 iCRT3 5 mg/kg·d),于造模第28 d处死小鼠。小鼠皮肤取材后,通过HE染色及Masson染色观察到经BLM诱导的模型组小鼠背真皮、表皮厚度较对照组皮肤均明显增加(P<0.05),同时模型组的皮脂腺、毛囊等皮肤附属器明显减少,脂肪层厚度变薄并被纤维组织包绕,模型组皮肤胶原沉积较对照组增加;通过免疫组织化学染色在组织学层面鉴定α-SMA表达情况,发现模型组及治疗组α-SMA在皮肤组织中均高表达,α-SMA阳性表达在血管周围较对照组明显增加;通过ELISA方法检测出模型组小鼠血清中IL-6及IL-17表达量较对照组明显升高(P<0.05),治疗组小鼠血清中IL-6及IL-17的表达量较模型组明显下降(P<0.05);提取皮肤微血管片段,通过q-PCR检测到模型组及治疗组小鼠皮肤微血管中β-联蛋白的mRNA基因表达水平较正常组升高;通过Western印迹检测皮肤微血管Wnt5A、β-联蛋白、α-SMA、col1A1的蛋白质表达情况,发现纤维化相关蛋白质α-SMA及col1A1在模型组表达升高,较对照组有统计学差异(P<0.05),治疗组较模型组表达下降(P<0.05),Wnt通路相关蛋白质β-联蛋白及Wnt5A在模型组表达明显升高,较之对照组有统计学差异(P<0.05)。本研究提示,BLM能成功诱导小鼠系统性硬化症皮肤表型,Wnt通路的异常激活参与了BLM诱导的硬皮病小鼠皮肤微血管病变,特异性Wnt通路抑制剂iCRT3可能通过直接或间接的方式下调细胞因子IL-6及IL-17,从而降低BLM诱导的小鼠皮肤微血管中的α-SMA及col1A1蛋白质表达,改善小鼠皮肤微血管病变,干预BLM诱导的小鼠血管病变的进展。