柳州市行道树资源调查与结构特征分析

该研究通过对柳州市区主要道路园林绿化全面踏勘,在四城区中筛选出68条道路行道树进行现场调查和综合评价。结果表明:(1)柳州市行道树共有28种,隶属于17科21属,常绿树种与落叶树种比例及乡土树种与外来树种比例合理。(2)柳州市行道树中小叶榕和黄葛榕在各城区应用频度较高,树种组成结构相对单一。(3)季相树种在各城区应用频度不均衡,部分城区春季景观营造效果显著,而夏秋冬季相景观效果不显著。(4)绿化达标率和林荫路推广率离国家生态园林城市还有较大差距,物种丰富度和多样性指数有待提高。建议加大乡土树种的应用与推广,提高各城区物种丰富度及季相树种的应用,营造城市道路特色季相景观。该研究成果提出了发展乡土树种、丰富树种多样性及季相景观营造的技术建议,对柳州市行道树树种规划和建设提供了科学依据。     

Differential expression during development of ADP-ribosylation factors, 20-kDa guanine nucleotide-binding protein activators of cholera toxin

Cholera toxin exerts its effects on cells in large part through the ADP-ribosylation of guanine nucleotide-binding proteins. Toxin-catalyzed ADP-ribosylation is enhanced by approximately 20-kDa guanine nucleotide-binding proteins termed ADP-ribosylation factors (ARFs), which are allosteric activators of the toxin catalytic unit. Rabbit antiserum against a purified bovine brain ARF (sARF II) reacted on immunoblots with two approximately 20-kDa ARF-like proteins (sARF I and II) in tissue extracts from bovine, rat, frog, and chicken. Levels of ARF were higher in brain than in non-neural tissues. In rat brain, on the second postnatal day, amounts of sARF I and II were similar. By the 10th postnatal day and thereafter, sARF II predominated. Relative levels of ARF determined by immunoreactivity were in agreement with levels assessed in functional assays of cholera toxin-catalyzed ADP-ribosylation. Based on nucleotide and deduced amino acid sequences of human and bovine cDNAs, there appear to be at least six different ARF-like genes. Northern blots of rat brain poly(A)+ RNA were hybridized with cDNA and oligonucleotide probes specific for each of the human and bovine ARF genes. From the second to the 27th postnatal day, ARF 3 mRNA increased, whereas mRNAs for ARFs 2 and 4 decreased; and those for ARFs 1, 5, and 6 were apparently unchanged. Partial amino acid sequence of sARF II is consistent with it being either the ARF 1 or 3 gene product. The developmental changes in rat brain ARF parallel neuronal maturation and synapse formation.     

记山西榆社晚新生代鹿科化石两新种

本文记述了山西榆社盆地晚新生代鹿科化石中的两个新种:Eucladoceros proboulei sp.nov.和Procapreolus jinensis sp.nov.,并列出了已鉴定完毕的所有产于榆社盆地晚新生代地层的鹿类动物化石单.     

Plant regeneration through somatic embryogenesis in root-derived callus of ginseng (Panax ginseng C. A. Meyer)

Summary Callus culture was initiated from expiants of mature root tissues of ginseng (Panax ginseng C.A. Meyer) on MS medium enriched with 2,4-D. The ageing callus produced numerous embryoids in this medium. Reculture of these embryoids in media (1/2 MS or B5) supplemented with benzyladenine and gibberellic acid resulted in profuse plantlet regeneration.     

江苏省区域农业生态经济的时空变异分析

以江苏省徐连、沿海、宁镇扬、沿江和太湖5个经济区及其9个代表县市区域为研究对象,基于"社会-生态-经济"的系统分析,建立了包括目标层、准则层和指标层3个层次多指标的农业生态经济综合评价指标体系,采用主成分分析方法对评价指标体系进行检验、筛选,并以江苏省为案例,综合分析了农业生态经济系统的时空变异特征。结果表明:江苏省农业生态经济发展水平的时空变异明显,空间上,徐连、沿海、宁镇扬、沿江和太湖5个经济区表现出由北向南逐渐上升的趋势,且随时间的推移逐渐上升;时间上,徐连和太湖经济区农业生态经济发展水平在1999—2008年间呈持续上升,处于良好或优质协调状态。虽然两经济区的农业生态环境-经济发展协调发展水平均较高,但差距较大,徐连和太湖经济区的农业生态环境-经济发展协调度从1999年到2008年呈逐渐下降趋势,但总体上仍处于良好或优质协调状态。     

甘肃兴隆山主要森林类型凋落物累积量及持水特性

2010年,采用野外实地观测与室内浸水法,对甘肃兴隆山6种主要森林类型(青杆林、青杆-白桦林、山杨-白桦林、灌丛林、落叶松林、油松林)林下凋落物的累积量、持水量、持水率和吸水速率进行了研究.结果表明:不同森林类型凋落物层累积量在13.40～46.32 t·hm-2,为油松林＞青杆-白桦林＞落叶松林＞青杆林＞灌丛林＞山杨-白桦林,且针叶林累积量高于阔叶林;半分解层累积量所占比例均高于未分解层.凋落物最大持水率为185.5％～303.6％,落叶松林最大,油松林最小,持水率与浸水时间呈对数关系;针叶林未分解层持水率均小于半分解层,而阔叶林则相反.凋落物最大持水量在3.94～8.59 mm,为油松林＞落叶松林＞青杆-白桦林＞青杆林＞灌丛林＞山杨-白桦林;持水量与浸水时间存在对数关系;半分解层持水量均大于未分解层.凋落物吸水速率与浸水时间存在幂函数关系,在浸水前1h内,吸水速率均直线下降,而浸水1.0h后吸水速率较小,且不同时段间变化较小;半分解层吸水速率高于未分解层.凋落物有效拦蓄量(深)为青杆-白桦林(5.97 mm)＞油松林(5.59 mm)＞落叶松林(5.46 mm)＞青杆林(4.30 mm)＞灌丛林(3.03 mm)＞山杨-白桦林(2.13 mm).     

专一转化人参二醇类皂苷Rb1为Rd的真菌菌株的筛选

于2009年的7－10月间在辽宁省的桓仁,吉林省的集安、靖宇、抚松等药材产区采集人参及人参根际土壤样品45份。通过真菌分离和培养,共获得真菌菌株105株,经形态学鉴定分属于15属48种。通过活性筛选,得到具有转化人参总皂苷活性的菌株25株,其中菌株SR87和SR105对人参皂苷Rb1具有专一转化活性。通过TLC和HPLC检测,其转化产物为人参皂苷Rd。经形态学鉴定,确定阳性菌株SR87为莫勒接霉Zygorhynchus moelleri,SR105为灰绿犁头霉Absidia glauca。这两株真菌均有较高的转化潜力,可以应用于制备人参皂苷Rd。     

黄土丘陵区坡面整地和植被耦合下的土壤水分特征

水分是干旱半干旱地区植被恢复的主要环境制约因子。在黄土高原小流域,合理整地能够有效截留降雨补给土壤水,进而促进植被恢复。选择地处甘肃定西的半干旱黄土小流域为研究区,基于野外实测数据,分析不同植被和整地方式(柠条水平阶、山杏水平沟、侧柏反坡台,油松反坡台)综合影响下的土壤水分特征。采用最优分割法将不同整地方式土壤水分垂直层次划分为活跃层,次活跃层和相对稳定层。结果表明:生长季不同整地方式土壤水分的变化与降水量的变化密切相关,不同月份以及不同深度各整地方式土壤水分之间差异显著(P0.05)。根据土壤水分垂直变化特征,山杏水平沟水分活跃层与次活跃层为0—80cm,其深度范围均大于其他3种整地方式,而柠条水平阶土壤水分均在30 cm以下较为稳定,其深度范围均小于其他3种整地方式。不同整地方式土壤水分含量具体表现为:山杏水平沟侧柏反坡台柠条水平阶油松反坡台。     

Quorum Sensing System Used as a Tool in Metabolic Engineering

Quorum sensing (QS) is a ubiquitous cell–cell communication mechanism in microbes that coordinates population‐level cell behaviors, such as biofilm production, virulence, swarming motility, and bacterial persistence. Efforts to engineer QS systems to take part in metabolic network regulation represent a promising strategy for synthetic biology and pathway engineering. Recently, design, construction, and implementation of QS circuits for programmed control of bacterial phenotypes and metabolic pathways have gained much attention, but have not been reviewed recently. In this article, the architectural organizations and genetic contributions of the naturally occurring QS components to understand the mechanisms are summarized. Then, the most recent progress in application of QS toolkits to develop synthetic networks for novel cell behaviors creation and metabolic pathway engineering is highlighted. The current challenges in large‐scale application of these QS circuits in synthetic biology and metabolic engineering fields are discussed and future perspectives for further engineering efforts are provided.