Mutagenesis and mutation transfer induced by ultraviolet light in plasmid-cloned DNA

We describe here simple techniques for increasing the frequency of UV-induced mutations in a DNA fragment cloned in plasmid pBR322. Irradiation of both the host and the plasmid DNA before transformation is necessary to produce new mutations in the plasmid DNA, presumably because the UV-damaged pBR322 replicon cannot efficiently induce the error-prone repair pathway of Escherichia coli. In contrast, U V irradiation of the plasmid DNA alone before transformation primarily causes the transfer of preexisting mutations from the host chromosome to homologous DNA present in the plasmid. The only other kind of mutants obtained were large deletions of the plasmid DNA. Two chromosomal mutations from the host galK gene and one from the lacZ gene have been transferred to the plasmid by UV irradiation of the plasmid DNA alone. The technique can thus be of general use.     

Graft union formation in artichoke grafting onto wild and cultivated cardoon: An anatomical study

In order to develop a non-chemical method such as grafting effective against well-known artichoke soil borne diseases, an anatomical study of union formation in artichoke grafted onto selected wild and cultivated cardoon rootstocks, both resistant to Verticillium wilt, was performed. The cardoon accessions Belgio (cultivated cardoon) and Sardo (wild cardoon) were selected as rootstocks for grafting combinations with the artichoke cv. Romolo. Grafting experiments were carried out in the autumn and spring. The anatomical investigation of grafting union formation was conducted by scanning electron microscopy (SEM) on the grafting portions at the 3rd, 6th, 10th, 12th day after grafting. For the autumn experiment only, SEM analysis was also performed at 30 d after grafting.     

江西武夷山中亚热带南方铁杉针阔混交林群落组成与结构

长期监测型固定样地是研究物种分布格局、群落动态和生物多样性维持机制等森林生态系统特征、过程与机理的重要平台。我国亚热带地区已建立的森林固定样地多为阔叶林类型,而针叶(阔叶混交)林类型十分有限。按照巴拿马Barro Colorado Island大型森林固定样地的建设规范,于2014年在江西武夷山国家级自然保护区内海拔1800 m左右的南方铁杉(Tsuga chinensis var. tchekiangensis)天然种群分布区域建立中亚热带针阔混交林6.4 hm~2固定样地。木本植物调查结果表明:(1)样地内胸径≥1 cm的木本植物共有29科53属89种,显著低于我国亚热带阔叶林样地平均水平,但显著高于温带针叶(阔叶混交)林样地平均水平;(2)在区系组成上,科以热带成分为主,而属以温带成分为主;(3)样地内独立个体数密度为2252株/hm~2,与温带针叶(阔叶混交)林平均水平相当,但显著低于亚热带阔叶林平均水平;(4)胸高断面积为37.89 m~2/hm~2,与亚热带阔叶林样地平均水平相当,但显著低于温带针叶(阔叶混交)林平均水平;(5)群落成层现象显著,优势种明显,多度排名前4位的物种的个体数占总个体数的55%,而排名后40的物种仅占1%;(6)群落总径级结构呈倒"J"型分布,其中胸径≤10 cm的小径木占总个体数的76.9%,而胸径30 cm的大径木仅占5.3%;(7)主要树种的径级结构有偏正态分布和"L"型分布等类型,但它们的种群在空间上均呈现显著的聚集分布特征;(8)南方铁杉虽然是群落现阶段最重要的优势种,但它的种群更新缓慢。研究结果充分显示该样地对中国森林多样性监测以及南方铁杉种群保育的重要意义。     

Activatable fluorescent probes in fluorescence-guided surgery: Practical considerations

Fluorescence-guided imaging during surgery is a promising technique that is increasingly used to aid surgeons in identifying sites of tumor and surgical margins. Of the two types of fluorescent probes, always-on and activatable, activatable probes are preferred because they produce higher target-to-background ratios, thus improving sensitivity compared with always-on probes that must contend with considerable background signal. There are two types of activatable probes: 1) enzyme-reactive probes that are normally quenched but can be activated after cleavage by cancer-specific enzymes (activity-based probes) and 2) molecular-binding probes which use cancer targeting moieties such as monoclonal antibodies to target receptors found in abundance on cancers and are activated after internalization and lysosomal processing (binding-based probes). For fluorescence-guided intraoperative surgery, enzyme-reactive probes are superior because they can react quickly, require smaller dosages especially for topical applications, have limited side effects, and have favorable pharmacokinetics. Enzyme-reactive probes are easier to use, fit better into existing work flows in the operating room and have minimal toxicity. Although difficult to prove, it is assumed that the guidance provided to surgeons by these probes results in more effective surgeries with better outcomes for patients. In this review, we compare these two types of activatable fluorescent probes for their ease of use and efficacy.     

Recent changes in the plant composition of wetlands in the Jura Mountains

Aim

To assess vegetation changes in montane fens and wet meadows and their causes over 38 years.

Location

Wetlands, Jura Mountains (Switzerland and France).

Methods

Plots were inventoried in 1974 and re‐located in 2012 (quasi‐permanent plots) on the basis of sketches to assess changes in plant communities. The 110 plots belonged to five phytosociological alliances, two in oligotrophic fens (Caricion davallianae, Caricion fuscae) and three in wet meadows (Calthion, Molinion, Filipendulion). Changes between surveys were assessed with NMDS, and changes in species richness, Simpson diversity, species cover and frequency and the causes of these changes were evaluated by comparing ecological indicator values.

Results

Changes in species composition varied between alliances, with a general trend towards more nutrient‐rich flora with less light at ground level. Species diversity declined, with a marked decreasing trend for the typical species of each alliance. These species were partly replaced by species belonging to nitrophilous and mesophilous grasslands. However, no trend towards drier conditions was detected in these wetlands. The largest changes, with an important colonization by nitrophilous species, occurred in the Swiss sites, where grazing was banned 25 years ago. As a result of floral shifts, many plots previously belonging to fens or wet mesotrophic meadows shifted to an alliance of the wet meadows, generally Filipendulion. Moreover, communities showed a slight trend towards more thermophilous flora.

Conclusions

The investigated wetlands in the Jura Mountains have suffered mainly from eutrophication due to land‐use abandonment and N deposition, with a loss of typical species. Areas with constant land use (grazing or mowing) showed less marked changes in species composition. The most important action to conserve these wetlands is to maintain or reintroduce the traditional practices of extensive mowing and livestock grazing in the wetlands, especially in areas where they were abandoned 25 years ago. This previous land‐use change was intended to improve fen conservation, but it was obviously the wrong measure for conservation purposes.     

新疆天山南坡中段种子植物区系垂直分布格局分析

对植物多样性垂直分布格局及其维持机制的研究可以有效揭示植物物种多样性分布特征及其环境影响因子。本文通过野外调查、查阅标本并结合相关文献资料,对天山南坡中段种子植物区系沿海拔梯度的分布格局进行了系统研究。结果显示,在大区域尺度上,科属种的物种丰富度随海拔升高均呈先增加后减少的趋势,且最高值出现在中低海拔1900~2000 m处;不同生活型植物沿海拔梯度的变化格局有所不同,其中,乔木、一年生草本、藤本及寄生植物表现出随海拔升高物种丰富度逐渐降低的趋势,灌木、多年生草本及二年生草本植物物种丰富度则呈先增加后减少的变化趋势;从植物区系地理成分来看,世界分布所占的比重沿海拔梯度升高呈先增加后减少的趋势;温带地理成分所占的比重沿海拔梯度升高呈缓慢上升趋势;古地中海地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势;热带地理成分所占的比重沿海拔升高呈逐渐下降的趋势;东亚地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势。对该分布格局与当地干旱的气候条件及海拔梯度上热量和水分条件的变化相适应。     

Nothia ex gr. excelsa (Grzybowski, 1898), ‘flysch-type’ agglutinated foraminifera from the Karpatian (Early-Miocene) of Hungary

Abstract

Nothia ex gr. excelsa (Grzybowski, 1898) branched, agglutinated, tubular foraminifera is documented for the first time from the Karpatian (latest Burdigalian) molasse sediments of the Paratethys. Excellently preserved specimens allowed the study of the macro- and microstructure of the test using reflected and polarized light microscopes, SEM and Raman spectroscopy. The mineralogical components of the agglutinated grains, the appearance of the protruded aperture with a scalloped-edge, the microstructure of the bilamellar wall, the presence of the calcite microgranular cement could all be described in detail. Based on autecology, the test morphology and the associated fauna indicate that Nothia ex gr. excelsa was a surface-dwelling detritivore with a seasonal-phytophagous mode of life.     

黄芪A6组分对流感病毒感染小鼠的防治作用

用黄芪生药1250～5000mg／kg,连续给药小鼠5d,其A6组分对100LD50或100ID50感染的BALB／C小鼠都有明显的预防和治疗作用,可降低感染幼鼠的死亡率和延长其平均存活天数;降低感染成年鼠的肺湿重。经X2和t检验,有显著性差异。且预防效果优于治疗。早期给药疗效较好。