Antimetabolic activities of 2-fluoro-L-histidine.

2-Fluoro-L-Histidine inhibits protein synthesis in various cell cultures, as measured by ³H-leucine incorporation. This histidine analog also inhibits the cytopathogenicity of a number of RNA and DNA viruses in primary and continuous cell cultures; it blocks the transformation of normal mouse (MO) cells by murine sarcoma virus, and partially suppresses the release of murine leukemia virus by a continuously infected mouse cell line (JLSV5). In human skin fibroblasts, it reduces the interferon-inducing capacity of poly(I)·poly(C). Inhibition of cell protein synthesis may be the common cause of the various effects. 4-Fluoro-L-histidine is essentially inert in all of the test systems examined.     

Silicon in rat liver organelles: Electron probe microanalysis

Summary Electron probe microanalysis of unfixed freeze-substituted rat liver tissue embedded in Spurr's low viscosity epoxy resin demonstrated the occurrence of Si as well as P, S, and Cl in the nucleus, nucleolus, mitochondria, and rough endoplasmic reticulum. Chemical analysis confirmed that the Si in the organelles did not originate from instrumental contaminants. This suggests that Si may be involved in the biochemistry of these subcellular organelles.Supported by Grant GM-08229-12-13 from the National Institutes of Health, USPHS.We are grateful to the Kevex Corporation and Mr. Glenn W. Meyer, Sales Engineer, for the use of the Kevex X-ray spectrometer; we wish to thank as well the Perkin-Elmer Corporation and their Western Branch Manager, Mr. Michael E. Mullen and Senior Microscopist, Mr. Minoru Shinorhara, for use of and assistance with the Hitachi HU 12 A transmission electron microscope. We also wish to acknowledge Mary Louise Chiappino for her technical assistance in preparing the thin sections, the final micrographs and the X-ray photographs, and Darlene Lum for technical assistance in the laboratory.     

Flavonoids and tannins of Acacia species

The heartwoods of Acacia giraffae and A. galpinii were selected from South African Acacias as representative of those with abnormally high and minimal tannin contents respectively. A. galpinii contains amongst other analogues, the first natural (+)-2,3-trans-3,4-trans-teracacidin (7,8,4′-trihydroxy-flavan-3,4-diol and novel 3-O-methyl-, 7,8-di-O-methyl- and 7,8,4′-tri-O-methylflavonol analogues. (−)-2,3-cis-3,4-cis-Melacacidin (7,8,3′,4′-tetrahydroxyflavan-3,4-diol) is also present, but tannins are absent. By contrast, from the large excess of leueofisetinidin tannins which characterizes the wood of A. giraffae, only (+)-catechin, (+)-2,3-trans-3,4-trans-leucofisetinidin (7,3′,4′,trihydroxyflavan-3,4-diol and all-trans-(+)-leueofisetinidin-(+)-catechin could be isolated.     

Sex and side differences and correlations between quantitative palmar characteristics in a sample Sardinian population

Differences between the sexes and between the sides and the correlations between four quantitative characteristics of palmar dermatoglyphics in a sample population of 809 individuals (418 males and 391 females) from the city of Cagliari, Sardinia, are tested. Males have a greater number of ridges than females, shown by a greater a-b ridge count and A-d ridge count, and a more transverse slope of the main lines, shown by a greater main line index and papillary number. The left palm shows a greater number of ridges than the right palm between the A line and the triradius d and between the triradii a and b, with a lower main line index and papillary number. The a-b ridge count has a negative correlation with the main line index and with the papillary number and a positive one with the A-d ridge count; these correlations are greater in the left palms, especially in the males.     

浙江省生境质量时空演变与生态红线评估

生境质量是反映生物多样性状况与局地生态功能的重要指标,在高质量发展背景下研究区域生境质量的时空演变具有重要意义。以浙江省为研究区,基于InVEST模型、热点分析及地理探测器模型探究生境质量的时空演变与影响因素,并利用生境质量结果对浙江省生态红线开展了定量评估。结果表明:(1)2000-2015年,浙江省生境质量均值呈减速下降趋势,空间上形成了西北、西南、中东高和东北、中部低的分布格局;生境退化度呈现"中心-外围"的圈层辐射结构。(2)热点分析显示,生境质量与生境退化度在乡镇尺度上集聚特征相似、冷热点空间分布趋势相反。(3)地理探测分析发现,地形(高程、坡度)是影响浙江省生境质量的主要因素,植被因素(NPP、NDVI)的贡献度随时间推移逐渐增大;浙江省生境质量空间分异受到自然因子与社会经济因子的协同作用。(4)浙江省生态红线的生境质量整体较高且稳定,不同红线类型的生境质量存在差异;高生境质量区与生态红线的错位区域主要分布在浙西南、西北部山区,而北部、中部以及东部相对较少。基于此,对生态红线调整、区域生态功能区划提出对应的策略,以期提升浙江省生态空间管控。     

不同栖息地状态下外来种入侵及对本地种生存影响的模拟

外来种入侵引起的生态及经济问题日益严重,人类活动导致大规模栖息地持续变化的背景下,外来种的入侵过程及本地物种多样性的演化更为复杂.在Tilman多物种共存模型基础上,建立了栖息地持续变化条件下的外来种入侵干扰模式,分别模拟了栖息地不变、持续毁坏及持续恢复条件下的外来种入侵及对本地物种多样性的生态影响.模拟结果表明:(1)拓殖率小(入侵性弱)的外来种不能成功定殖,栖息地的持续变化对其没有任何影响.(2)拓殖率增大的外来种入侵过程复杂,栖息地持续毁坏导致其灭绝时间相比于栖息地不变时明显推迟,栖息地持续恢复使其灭绝提前;一定时间内持续增加栖息地可以减小此类外来种入侵危害.(3)拓殖率足够大的外来种能够成功定殖,快速定殖-扩散的入侵过程不会因栖息地毁坏而迅速改变,其响应具有时间滞后性;栖息地持续恢复也有利于其迅速蔓延,占有率呈线性疯狂增长.(4)在具有外来种入侵的本地生态系统中,栖息地持续改变(增加或减少)对本地物种多样性的发展均不利.     

草木樨状黄芪变异系中甲硫氨酸代谢相关cDNA的分子克隆及其在大肠杆菌中的表达

利用mRNA差异显示技术(differential display)从草木樨状黄芪耐甲硫氨酸变异系中分离到一差异cDNA片段,命名为tm03(360bp)。mRNA杂交结果显示,该片段只在变异苗中表达,初步确定其与甲硫氨酸代谢相关。测序后在Genebank搜寻,未发现有同源序列。进一步分析表明,该cDNA克隆可编码完整的蛋白。在该基因片段两端分别合成含HindⅡ和BamH Ⅰ酶切位点的引物,用PCR扩增后亚克隆到pRSET A表达载体,转化宿主菌JMl09(DE3),经IPTG诱导表达了N′端含6个组氨酸的蛋白质,分子量约为14kD,为进一步研究该蛋白的结构和生物学功能奠定基础。     

淀粉分支酶sbeIIb基因RNA干涉片段转化玉米自交系的研究

玉米高直链淀粉育种是玉米分子育种的一个重要研究方向.本实验中,首先研究了不同诱导愈伤培养基对再生体系的影响,确定了LS+2,4-D 2.0 mg/L+L-pro 700 mg/L+CH 500 mg/L+3 %蔗糖为诱导培养基.同时,构建并验证了含有淀粉分支酶sbeIIb基因双干涉片段载体和胚乳特异性启动子的表达载体pCAMBIA 1301+Glu+1620,并转入根癌农杆菌EHA105,以农杆菌转化法转化玉米自交系178.通过PCR检测,5株转化株表现阳性,初步证明了干涉片段已整合入玉米基因组中.     

Breeding bacterial blight-resistant hybrid rice with the cloned bacterial blight resistance gene Xa21

The cloned bacterial blight (BB) resistance gene Xa21 was transferred into Minghui63, a widely used restorer line of indica hybrid rice in China, through an Agrobacterium-mediated system. Molecular and resistance analyses revealed that the Xa21 gene was integrated in the genomes of transgenic plants and their progeny inherited resistance stably. For the purpose of hybrid breeding, Xa21 transgenic homozygous restorer lines were selected through `within-lane' dosage comparison of hybridization signal in combination with PCR and resistance analyses. The selected transgenic restorer lines were then crossed with a commonly used sterile line, Zhenshan97A, to produce Xa21 transgenic hybrid rice, Shanyou63-Xa21. The hybrid rice plants with Xa21 displayed high broad-spectrum resistance to Xanthomonas oryzae pv. oryzae (Xoo) races and maintained elite agronomic characters of Shanyou63. The propagation of this BB-resistant hybrid variety with Xa21 will benefit rice production.