葡萄蔗糖转化酶基因家族的生物信息学及响应逆境胁迫分析

蔗糖转化酶(invertase, INV)在植物生长发育和抵御胁迫中发挥着重要作用。研究从葡萄基因组数据库中鉴定出19个蔗糖转化酶基因,对基因结构和编码蛋白质的理化性质进行生物信息学分析,并利用qRT-PCR技术分析基因在不同激素和非生物胁迫条件下的表达特征,为进一步探索葡萄INV基因家族参与葡萄逆境响应提供了一定的理论依据。结果表明,(1)该基因家族编码蛋白的氨基酸长度在150～766 aa之间,理论等电点介于4.43～9.1之间,亚细胞定位预测发现其主要在细胞质中表达,此外液泡和细胞壁也存在部分基因表达;(2)共线性结果显示VvCINV与其他5个物种复制频率较高;(3)保守基序分析表明VvCwINV包含了所有的保守基序,且Glyco＿32和Glyco＿hydro＿100是VvINV基因主要结构域;(4)组织特异性表达分析发现多数基因在葡萄生长发育进程中都有表达;(5)qRT-PCR分析结果显示,VvINV基因家族在叶片中对激素处理和非生物胁迫的响应出现上调,VvCINV1在50 mg/L GA₃和10%PEG处理后上调表达极显著,VvCINV4在盐胁迫、ABA...     

氯虫苯甲酰胺对黑肩绿盲蝽实验种群的影响

采取稻茎浸渍法测定了氯虫苯甲酰胺对黑肩绿盲蝽毒力,利用生命表技术研究了氯虫苯甲酰胺对黑肩绿盲蝽实验种群的影响,为协调水稻害虫的化学防治和生物防治提供参考。结果表明,氯虫苯甲酰胺对黑肩绿盲蝽若虫LC50和LC10分别为83.5mg/L和61.3 mg/L,氯虫苯甲酰胺对黑肩绿盲蝽成虫LC50和LC10分别为64.3 mg/L和39.0 mg/L。氯虫苯甲酰胺对黑肩绿盲蝽若虫和成虫的LC10分别大于和接近于大田使用剂量40mg/L。以大田使用剂量40 mg/L氯虫苯甲酰胺稻茎浸渍法处理黑肩绿盲蝽3龄若虫后,其产卵期、寿命和产卵量降低了4.3 d、3.0 d和22.0粒,与对照相比差异显著,表明氯虫苯甲酰胺对当代成虫寿命与生殖力影响较大;药剂处理后次代种群的成虫前期延长了2.3 d;存活率、平均日产卵量跟对照相比明显降低;种群净增值率、周限增长率、内禀增长率跟对照相比明显降低,分别为21.0(对照63.3)、18.8(对照19.2)、0.16(对照0.22),而种群加倍时间延长为4.3(对照3.2);这些结果表明,在40 mg/L浓度下,氯虫苯甲酰胺能够降低黑肩绿盲蝽种群的增长。     

An in vivo experimental system to study sugar phloem unloading in ripening grape berries during water deficiency stress

An in vivo experimental system-called the 'berry-cup' technique-was developed to study sugar phloem unloading and the accumulation of sugar in ripening grape berries. The berry-cup system consists of a single peeled grape berry immersed in a buffer solution in a cup prepared from a polypropylene syringe. A small cross-incision (2 mm in length) is made on the stylar remnant of a berry during its ripening phase, the skin of the berry then being easily peeled off, exposing the dorsal vascular bundles without damaging either these or the pulp tissue of the berry. The sites of sugar phloem unloading are thus made directly accessible and may be regulated by the buffer solution. In addition, the unloaded photoassimilates are easily transported into the buffer solution in the berry-cup. With the berry-cup technique, it takes 60 min to purge the sugar already present in the apoplast, after which the amount of sugar in the buffer solution is a direct measure of the sugar unloading from the grape berry phloem. The optimum times for sampling were 20 or 30 min, depending on the type of experiment. Sugar phloem unloading was significantly inhibited by the inclusion of either 7.5 mm NaF or 2.5 mm PCMB in the buffer solution. This study indicates that sugar phloem unloading in ripening grape berries is via the apoplastic network and that the process requires the input of energy. The system was shown to be an appropriate experimental system with which to study sugar phloem unloading in ripening grape berries, and was applied successfully to the study of berry sugar unloaded from grapevines subjected to water stress. The results showed that water deficiency inhibits sugar unloading in grape berries.     

A local influence approach applied to binary data from a psychiatric study

Recently, a lot of concern has been raised about assumptions needed in order to fit statistical models to incomplete multivariate and longitudinal data. In response, research efforts are being devoted to the development of tools that assess the sensitivity of such models to often strong but always, at least in part, unverifiable assumptions. Many efforts have been devoted to longitudinal data, primarily in the selection model context, although some researchers have expressed interest in the pattern-mixture setting as well. A promising tool, proposed by Verbeke et al. (2001, Biometrics 57, 43-50), is based on local influence (Cook, 1986, Journal of the Royal Statistical Society, Series B 48, 133-169). These authors considered the Diggle and Kenward (1994, Applied Statistics 43, 49-93) model, which is based on a selection model, integrating a linear mixed model for continuous outcomes with logistic regression for dropout. In this article, we show that a similar idea can be developed for multivariate and longitudinal binary data, subject to nonmonotone missingness. We focus on the model proposed by Baker, Rosenberger, and DerSimonian (1992, Statistics in Medicine 11, 643-657). The original model is first extended to allow for (possibly continuous) covariates, whereafter a local influence strategy is developed to support the model-building process. The model is able to deal with nonmonotone missingness but has some limitations as well, stemming from the conditional nature of the model parameters. Some analytical insight is provided into the behavior of the local influence graphs.     

Comparative population growth and life table demography of the rotifer Asplanchna girodi at different prey (Brachionus calyciflorus and Brachionus havanaensis) (Rotifera) densities

Population growth and life table demography of the predatory rotifer A. girodi using spineless Brachionus calyciflorus and spined Brachionus havanaensis as prey at densities of 1, 2, 4 and 8 ind. ml^–1 at 25°C were studied. Regardless of the prey species, the population of A. girodi increased with increasing availability of Brachionus in the medium. At any given prey density, A. girodi fed B. calyciflorus showed consistently better growth than when fed B. havanaensis. The maximum population densities of A. girodi varied from 0.28 to 1.8 ind. ml^–1 depending on the prey species and the density. The rate of population increase observed in population growth studies varied from 0.17 to 0.43 day^–1 when fed B. calyciflorus and 0.09 to 0.27 day^–1 when fed B. havanaensis. Male population of A. girodi was closely related to female density. The lowest average lifespan was observed for A. girodi when fed B. havanaensis at 1 ind. ml^–1, while the converse was the case when fed B. calyciflorus at comparable prey concentration. Net reproductive rates varied from 16 to 26 offspring female^–1 lifespan^–1 depending on the prey species and concentration. Generation time of A. girodi decreased with increasing food concentrations for both the prey species. The rates of population increase obtained from life table demography were lower for A. girodi when fed B. havanaensis than when fed B. calyciflorus.     

Role of the egg parasitoid Trichogramma minutum in biological control of the grape berry moth, Endopiza viteana

During a survey for natural enemies of thegrape berry moth (GBM) Endopiza viteana(Clemens) in northwestern Pennsylvania, wefound that Trichogramma minutum Riley isthe only native egg parasitoid with thepotential to limit berry damage by preventingegg hatch. Natural parasitism, however, wasfound to be unreliable for providing economicpest suppression. Early season populations ofthe parasitoid are extremely low and may be theresult of inadequate alternative host eggs foroverwintering. Also, wild grapes and theirwooded habitats were found to be favored byT. minutum. Parasitism was low incultivated grapes and in wild grapes growingclose to commercial vineyards (possibly due tothe deterrent effect of insecticides) andhighest in sites 1.5 km from commercialvineyards. Adult T. minutum emergingfrom GBM eggs were exceptionally small andshowed little vigor. Parasitized eggs oftenfailed to produce adult parasitoids. Pre-adults in such eggs had poorly formed mouth-parts or lacked them altogether. Inundativereleases of laboratory-reared T. minutumin border rows of vineyards are suggested as apossible alternative to the current practice ofapplying carbamate and organophosphateinsecticides, which are inimical to beneficialarthropods.     

动态生命表寿命数收集与处理过程中常见问题的探讨

种群动态生命是研究野生动物存活过程的有用工具,而其可靠性则依赖于生命数据收集与处理过程中的正确性。章就野生动物动态生命表收集和处理过程中常见的右删失数据处理问题、个体死亡时间估计、同生群初始值N0估计以及早期死亡数据的估算问题提出了一点建议和讨论。     

常见寿命数据类型及生命表的编制方法

生命表是描述种群死亡过程的有用工具,介绍了4种常见的寿命数据类型;寿终数据,右删失数据,左删失数据和区间型数据特征及其相应的数据分析处理方法即生命表法,乘积限估计和Turbull估计法,对生命表法和乘积限估计法应用上的特点进行了比较,同时还对特殊的寿命数据类型－－截断数据做了简要介绍。     

Effects of food limitation and temperature on cladocerans from a tropical Brazilian lake

Food limitation was tested in the laboratory by individual growth and reproduction of two cladoceran species, Ceriodaphnia richardi and Daphnia gessneri, from the shallow tropical Brazilian Lake Monte Alegre. The cladocerans were fed cultivated green alga Scenedesmus spinosus in concentrations of 0.20, 0.10, 0.05, and 0.025 mg C l⁻¹. Higher biomass and growth rates occurred in the two highest-food concentrations; the two lowest ones negatively affected clutch size and first reproduction. The threshold food concentration is lower than 0.025 mg C l⁻¹ and the incipient limiting level is a value between 0.10 and 0.20 mg C l⁻¹. The largest species, D. gessneri, was more sensitive to low food concentrations. The effects of low and high temperatures (19 and 27°C) were evaluated by life table experiments with three cladocerans from the lake—Daphnia ambigua, D. gessneri, and Moina micrura—with no food limitation (1 mg C l⁻¹ of S. spinosus). Higher population growth rates for the three species were found at 27°C; better performance in most life table parameters was observed for the former two species at the highest temperature, D. gessneri being the most sensitive to the lowest temperature. There are indications that temperature is an important abiotic factor that constrains populations of cladocerans for a short period in winter in the lake, when temperature decreases to 18–19°C. However, its influence cannot be separated from a biotic factor such as food, whose effect is stronger in the cool season, when concentrations are lower and contribution of inedible algae is relatively higher.     

哺乳动物存活曲线类型的分析方法探讨

动物的存活曲线通常可分为3种类型：凸型（Ⅰ型或A型）、直线型（Ⅱ型或B型）和凹型（Ⅲ型或C型）。存活率曲线与存活曲线在概念上有一定的区别。存活率要经过对数转换（或者直接采用对数标尺）后才能得到存活曲线类型,从动物的存活率曲线上直接判读存活曲线类型可能会导致错误的结论。鉴于存活曲线分析研究中出现的问题,建议在进行物种存活曲线类型的分析时,务必先进行对数转换。