细胞实验中细胞生长及换液处理对实验结果的影响

利用所设计的核酶抑制转染了HBV的HEPG2细胞内病毒的复制,对所产生的病毒抗原的量进行统计学处理,从而观察到细胞生长和细胞培养液换液对结果的影响。结果表明,换液处理组与未换液处理组的抑制率不同;在96h,未经换液的孔抑制率出现了负值。细胞在80h后数目减少,镜检显示细胞状态不佳。应用细胞生长曲线和细胞换液处理对于实验结果有一定的修正作用。     

Hubbell's fundamental biodiversity parameter and the Simpson diversity index

Central to Hubbell's neutral theory of biodiversity is a universal, dimensionless fundamental biodiversity parameter that is the product of community size and speciation rate. One of the most important discoveries of Hubbell's theory is that the species‐abundance distribution and the species–area relationship of the neutral metacommunity is completely determined by this fundamental biodiversity parameter, although the diversity patterns of the local community are collectively determined by the biodiversity parameter and migration. Using the relative abundance of species and following the concept of heterozygosity of population genetics, here we developed an analytical relationship between this biodiversity parameter and the well‐known Simpson diversity index. This relationship helps bridge the evolutionary aspect of biodiversity to the ecological and statistical aspect of the diversity. The relationship between these two parameters suggests that diversity patterns of the metacommunity can also be equally described by the Simpson index. This relationship provides an alternative approach to interpret and estimate the fundamental biodiversity parameter for the metacommunity.     

黄土高原子午岭天然柴松林种群结构与动态研究

对黄土高原地区子午岭天然柴松(Pinus tabulaeformisf.shekannesis)林种群的结构和动态进行了研究。结果显示:柴松种群结构呈反J分布型,种群处于增长阶段;种群的密度随径级的增加而降低,种群密度与径级呈现出明显的负相关;4个函数(生存率函数、积累死亡率函数、死亡密度函数、危险率函数)估计值说明种群具有前期增长、后期稳定的特点,其存活曲线介于DeeveyⅡ型和DeeveyⅢ型之间;随时间推移,种群中树和大树数量逐渐增多,种群在20 a后开始大量进入成熟阶段。表明柴松在本研究区内生长更新良好,在无人为干扰条件下,柴松可通过自我调节能力而保持种群的稳定性。     

Landscape-scale variation in the seed banks of floodplain wetlands with contrasting hydrology in China

1. At a local scale, the species composition, diversity and spatial variation of wetland plant communities are determined primarily by spatial and temporal heterogeneity in their environments. Less is known about variation at a landscape‐level. The floodplain of the Changjiang (Yangtze) River in China includes hydrologically connected, subtropical wetlands with different hydrological characteristics. 2. We examined seed‐bank species composition and richness in marshes of two contrasting hydrological types: permanent marshes, fed by local runoff, and lakeshore marshes more closely connected to the regulated river. Lakeshore marshes are flooded annually to depth of approximately 1 m and during flooding they support an alternate, aquatic vegetation type. The soil seed bank in March was a comparative estimator of species diversity. At the beginning of the growing season it included seeds from both phases of alternating vegetation types associated with the annual hydrological cycle. 3. A regional pool of 101 species was detected in the seed banks of six wetlands associated with the river and its tributaries: 56 occurred in permanent marshes and 59 in lakeshore marshes, with only 15 common to both. Species rarefaction curves indicated that more species occurred in permanent than lakeshore marshes at equal numbers of individuals sampled. However, the more heterogeneous lakeshore seed banks were estimated (Chao 2) to have greater total species richness (81) than permanent marsh (60). 4. Analysis using Sørensen's coefficient of similarity and DCA ordination revealed complex variation, with much greater differences between hydrological types than within them, irrespective of geographical distance. The types also differed significantly in the composition of four functional groups of species. 5. Despite the potential for dispersal of propagules via the annually pulsing river system (hydrochory), at a regional and landscape scale, diversity is maintained largely by large‐scale temporal hydrological heterogeneity and smaller scale spatial and topographic heterogeneity.     

泡桐丛枝植原体tRNA异戊烯基焦磷酸转移酶基因克隆、原核表达及功能分析

【目的】为了鉴定植原体tRNA异戊烯基焦磷酸转移酶基因(tRNA-ipt)的表达及蛋白功能,探索植原体致病机理。【方法】对泡桐丛枝、桑萎缩、长春花绿变及苦楝丛枝植原体tRNA-ipt基因完整序列进行PCR扩增和生物信息学分析。对泡桐丛枝植原体tRNA-ipt基因进行原核表达并制备抗体。利用Western blot和FITC间接免疫荧光显微镜检测其在植原体中的表达。使用分光光度计分析该基因对大肠杆菌生长的影响,用ELISA测定转化菌株细胞分裂素含量。【结果】首次发现泡桐丛枝、桑萎缩、长春花绿变及苦楝丛枝植原体中完整tRNA-ipt基因,大小为876 bp,编码291个氨基酸,且N端均含有ATP/GTP结合位点保守序列(GPTASGKT)。4种植原体tRNA-IPT之间的氨基酸序列相似率为99.1%-99.5%,与同组植原体同源性在95.4%-99.3%,与其他组植原体同源性低于70%。SDS-PAGE结果显示tRNA-IPT蛋白在大肠杆菌中得到表达。首次获得泡桐丛枝植原体tRNA-IPT抗体并检测到该蛋白在泡桐发病组织中的特异表达。经过对转化菌株生长曲线及玉米素含量的测定,发现该基因能促进大肠杆菌后期生长和玉米素核苷的积累。【结论】4种植原体tRNA-ipt基因编码相同特性的功能蛋白,泡桐丛枝植原体tRNA-IPT蛋白能够在植原体中表达,根据该基因对异源菌株生长速率和激素合成的影响推断该蛋白可能参与植原体的细胞分裂素合成,在致病过程中起到重要作用。     

Technical note: Quantification of neurocranial shape variation using the shortest paths connecting pairs of anatomical landmarks

Three‐dimensional geometric morphometric techniques have been widely used in quantitative comparisons of craniofacial morphology in humans and nonhuman primates. However, few anatomical landmarks can actually be defined on the neurocranium. In this study, an alternative method is proposed for defining semi‐landmarks on neurocranial surfaces for use in detailed analysis of cranial shape. Specifically, midsagittal, nuchal, and temporal lines were approximated using Bezier curves and equally spaced points along each of the curves were defined as semi‐landmarks. The shortest paths connecting pairs of anatomical landmarks as well as semi‐landmarks were then calculated in order to represent the surface morphology between landmarks using equally spaced points along the paths. To evaluate the efficacy of this method, the previously outlined technique was used in morphological analysis of sexual dimorphism in modern Japanese crania. The study sample comprised 22 specimens that were used to generate 110 anatomical semi‐landmarks, which were used in geometric morphometric analysis. Although variations due to sexual dimorphism in human crania are very small, differences could be identified using the proposed landmark placement, which demonstrated the efficacy of the proposed method. Am J Phys Anthropol 151:658–666, 2013. © 2013 Wiley Periodicals, Inc.     

Modeling physical growth using mixed effects models

This article demonstrates the use of mixed effects models for characterizing individual and sample average growth curves based on serial anthropometric data. These models are advancement over conventional general linear regression because they effectively handle the hierarchical nature of serial growth data. Using body weight data on 70 infants in the Born in Bradford study, we demonstrate how a mixed effects model provides a better fit than a conventional regression model. Further, we demonstrate how mixed effects models can be used to explore the influence of environmental factors on the sample average growth curve. Analyzing data from 183 infant boys (aged 3–15 months) from rural South India, we show how maternal education shapes infant growth patterns as early as within the first 6 months of life. The presented analyses highlight the utility of mixed effects models for analyzing serial growth data because they allow researchers to simultaneously predict individual curves, estimate sample average curves, and investigate the effects of environmental exposure variables. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.     

Farm‐scale dispersal of Bactericera cockerelli in potato crops measured using Bt mark‐capture techniques

Natural populations of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), also known as tomato/potato psyllid, were marked in potato [Solanum tuberosum L. (Solanaceae)] crops using Bacillus thuringiensis Berliner (Bt) to investigate the impact of dispersal on crop infestation and management of potential insecticide resistance in New Zealand. The technique was adapted from previous studies that used conventional spray applications of Bt to mark Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), and identified marked individuals with selective microbiological assays and identification of characteristic crystal inclusions. Initially, marking rates of B. cockerelli were improved by using ultra‐low volume applications of undiluted Bt, but this result was not consistent. Several other pests and natural enemies were also marked. In mark‐capture studies, marked B. cockerelli were captured over 3 days on yellow sticky traps in small trap plots of potatoes at 60, 120, 180, 250, and 350 m from the sprayed crop. Bactericera cockerelli flight activity occurred throughout daylight hours with evidence of bimodal diurnal peaks. Significantly greater numbers of B. cockerelli were captured in downwind traps. The combined dispersal curve derived from two mark‐capture experiments estimated a mean dispersal distance for B. cockerelli of 100 m in 3 days and indicated that 10% of the population dispersed further than ca. 250 m. Over the period of a growing season, this level of dispersal suggests that B. cockerelli can disperse throughout a vegetable‐growing region, with implications for crop infestation and management of potential insecticide resistance.     

Low,but not high,doses of melatonin entrained a free-running blind person with a long circadian period

In a previous report, we were unable to entrain one out of seven totally blind people with free-running endogenous melatonin rhythms to 10 mg of exogenous melatonin. This person had the longest circadian period (24.9 h) of the group. We now find that this person can be entrained to 0.5 mg of melatonin, but not to 20 mg. These results are consistent with the idea that too much melatonin may spill over onto the wrong zone of the melatonin phase–response curve.