Selective determination of lithium in biological fluids using flow injection analysis

The use of flow injection analysis to automated extraction methods for the determination of lithium ion utilizing crown ethers or cryptands is demonstrated. The ion-pair extraction of cryptand 211, lithium, and resazurin exhibits a linear range for lithium ion of 70 ppb to 2.1 ppm. This method could tolerate up to 1000 ppm sodium ion. The chromogenic crown ether, 1-(2-hydroxy-5-nitrobenzyl)-1-aza-4,7,10-trioxacyclododecane, exhibits a linear range for lithium ion of 0.3 to 2 ppm. A sodium ion concentration of 230 ppm can be tolerated. Both extraction systems were used in the automated determination of lithium in blood serum and urine. Both methods agreed well with the known and/or atomic absorption values.     

Performance of 11 tree species under different management treatments in restoration plantings in a tropical dry forest

Ecological restoration in tropical dry forests urgently needs to incorporate experimental evidence to increase effectiveness. The main barriers for tree establishment are adverse microenvironmental conditions and competition with exotic grasses. Therefore, management should address such barriers in order to enhance tree performance. We evaluated the effect of plastic mulching, grass removal, and no management on survival after 2 months and stem volume and canopy size after 2 years and integrated response index (IRI) in plantings of 11 native tree species with different growth rates in pastures near the tropical dry forest of Chamela, Mexico. Results revealed that: (1) initial seedling mortality was minimal in all treatments (8%) and lowest under no management (2%); (2) plastic mulching, but not grass removal, leads to increased size for most species, irrespective of their growth rank; (3) a trade‐off between initial plant survival and size after 2 years occurred due to plastic mulching; and (4) most species showed similar values of the IRI because of high survival, stem volume, or canopy cover. Grass removal decreased early survival of all species and increased stem volume only for one slow‐growing species. The use of plastic mulching increased stem volume for slow‐growing species, whereas fast‐growing species developed larger canopies with that treatment. Effects of grass removal and mulching seem to be very species‐specific and not dependent in growth rank of species, although overall mulching seems to provide better conditions for seedling performance than grass removal alone.     

鄂尔多斯高原特有种四合木生长和繁殖的种群间变异与濒危机制

四合木为中国特有种,其分布区局限于鄂尔多斯高原的西部。为了认识四合木濒危的机制并为其保护提供理论依据。对四合木生活史的关键阶段－－繁殖进行了野外研究,由于分布区内存在较大的生境异质性,并受到了不同强度的人类干扰,所以不同生境条件下的6个群进行了取样,通过对四合木的营养生长和繁殖的比较分析。得出如下结论：（1）四合木植要朱的基径和冠幅和高度与年龄显著相关,但是与其茎和冠幅相关性更大,冠幅可作为个体大小的测度估计种群的大小结构;（2）冠幅大小呈负偏斜分布,通过不同种群冠幅与年龄的相关分析,得出冠幅的增长速率随种群的衰老耐减缓;（3）四合木的冠幅与其果实量和种子量相关关系显著,随着冠幅的增大,四合木植株的果实产量和种子产量也相应增加,但是这种关系存在种群间差异;（4）四合木的大部分群都处于衰老期,种群内个体的大小变异性很小,对于种群的生存有不利影响;（5）由于空间上四合木的大小结构以及反映四合木繁殖状况的植株果实产量,种子产量等参数在不同种群之间存在显著差异（P＜0．001）,因此应对不同的种群采取相应的管理措施以促进种群的更新和续存。     

西洋参冠瘿组织培养及其人参皂苷Re和人参皂苷Rg1的产生

考察了培养基组成、培养时间、接种量、pH值、肌醇浓度等对冠瘿组织生长及其人参皂苷含量的影响 ;用HPLC检测了冠瘿组织中人参皂苷Re和人参皂苷Rg1 的含量。高压纸层析电泳证实 ,根癌农杆菌Ti质粒上的T DNA片段已整合进入植物细胞核基因组中。在考察的 6种培养基中 ,White培养基最适合人参皂苷Rg1 的累积(0 0 95 % ) ,MS培养基最适合人参皂苷Re的累积 (0 194 % )。以MS为基本培养基培养 36d、32d时人参皂苷Re和人参皂苷Rg1 累积含量最高 (分别为 0 14 7%和 0 0 6 1% ) ;接种量为 4g、2g (FW flask) ,有利于人参皂苷Re和人参皂苷Rg1的累积 ;培养基pH 5 8时人参皂苷Re含量最高 (0 184 % ) ,培养基pH 5 6时人参皂苷Rg1 累积量最高 (0 0 5 4 % ) ;肌醇浓度为 0 0 5g L时 ,能促进人参皂苷Re合成 (0 182 % ) ,浓度为 0 30g L时 ,有利于人参皂苷Rg1 累积 (0 0 5 5 % )。     

抗桃根癌病菌的耐氰放线菌筛选及其抑菌作用研究

为了筛选耐氰并抗桃根癌病的微生物菌株,以不同浓度的KCN培养基作为选择培养基,以根癌农杆菌为靶标菌,通过平板对峙培养的方法,筛选出了耐氰放线菌G-19,其发酵液代谢产物对根癌农杆菌有明显的抑制作用,抑菌圈直径为21.66 mm。其抑菌作用主要表现在3个方面:使得病原菌的生长对数期缩短,菌体浓度处于低水平状态;使病原菌的细胞壁弯曲、皱缩,继之结构发生破裂,细胞质向边缘凝聚,中心变得稀薄,甚至形成空腔;使细胞膜的通透性增加,导致病原菌的细胞质液外泄;但未见到病原菌DNA的损伤。因此,认为G-19菌株抑菌的作用机理是使根癌病原菌的细胞壁结构破坏和膜透性增加。     

植物冠瘿生长调控及相关基因研究进展

阐述了植物冠瘿产生的影响因素及冠瘿的生长和调控,并对冠瘿发生有关的基因进行了综述。     

Cervical and crown outline analysis of worn Neanderthal and modern human lower second deciduous molars

Despite the general increase in digital techniques for dental morphometric analyses, only a few methods are available to study worn teeth. Moreover, permanent dentitions are studied much more frequently than deciduous teeth. In this study, we address both issues by providing a taxonomic classification of Neanderthal and modern human (MH) lower second deciduous molars (dm₂s) through the analysis of crown and cervical outlines. Crown and cervical outlines were obtained from a three‐dimensional (3D) digital sample of uniformly oriented dm₂s. Both outlines were centered on the centroid of their area and represented by 16 pseudolandmarks obtained by equiangularly spaced radial vectors out of the centroid. We removed size information from the oriented and centered outlines with a uniform scaling of the pseudolandmark configurations to unit Centroid Size. Group shape variation was evaluated separately for the dm₂ crown and cervical outlines through a shape–space principal component (PC) analysis. Finally, quadratic discriminant analysis of a subset of PCs was used to classify the specimens. Our results demonstrate that both outlines successfully separate the two groups. Neanderthals showed a buccodistal expansion and convex lingual outline shape, whilst MHs have buccodistal reduction and straight lingual outline shape. Therefore, we confirmed that the cervical outline represents an effective parameter for distinguishing between the two taxa when dealing with worn or damaged dm₂s. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc.     

豌豆茎基腐病病原菌分离鉴定及其对杀菌剂的敏感性测定

豌豆(Pisum sativum)是我国重要的豆类经济作物, 病害对豌豆生产造成重大经济损失。通过形态学观察、分子鉴定以及致病性测定, 最终确定引起豌豆茎基腐病的3种病原菌分别为尖孢镰刀菌(Fusarium oxysporum)、芸苔链格孢菌(Alternaria brassicae)和格氏镰刀菌(F. grosmichelii), 优势菌株为尖孢镰刀菌, 分离率为53.6%。室内毒力测定结果表明, 5种供试杀菌剂对3种病原菌的菌丝生长均有抑制作用, 其中咯菌腈和戊唑醇的抑菌效果最好。研究结果为豌豆茎基腐病的防治提供了科学依据。     

Growth and development of seminal and crown root systems in N-limited barley,and their contributions to nitrate acquisition during vegetative and generative growth

Barley (Hordeum vulgare L., cvs Golf and Laevigatum) was grown under nitrogen limitation, controlled by the relative rate of nitrate-N addition (RA), in solution culture. The seminal and crown root systems were kept apart, but in contact with the same nutrient solution throughout culturing. Growth, nitrate uptake, and in vitro nitrate reductase (NR) activity in the different root parts were studied at plant ages from 40 (late vegetative stage) to 110 (mid grain-filling) days. The RA was during this time interval stepwise decreased from 0.08 day^–1 to 0.005 day^–1. The ratio between seminal root dry weight and total plant dry weight decreased drastically during post-anthesis growth, whereas the contribution by crown roots remained unchanged. Tissue nitrogen concentrations in seminal roots did not change with time, but decreased in crown roots after day 80. The NR activity decreased with age in both seminal and crown roots. The V_max for net nitrate uptake decreased throughout the experiment in the seminal root system, but not in the crown root system. The kinetic properties (V_max and K_M) were used to calculate the nitrate concentration required to maintain a relative rate of nitrate-N uptake that equals the relative addition rate. These concentrations (2 to 5 mmol m^–3) were found to closely match actually measured nitrate concentrations in the nutrient solution (1 to 6 mmol m^–3). From uptake kinetics, it was deduced that the contribution by seminal roots to total nitrate uptake at these concentrations decreased from more than 50% in vegetative plants, to about 20% just after main shoot anthesis, and to less than 5% during grain-filling. ei]Section editor: H Lambers