Genetic analysis of feeding preference in two related species of Altica (Coleoptera: Chrysomelidae: Alticinae)

Abstract 1. Genetic analysis of feeding preference can make an important contribution to our understanding of the evolution of host‐plant selection in phytophagous insects. Two closely related flea beetles, Altica viridicyanea (Baly) and Altica fragariae Nakane, with separate host plants [Geranium wilfordii Maxim. and Duchesnea indica (Andrews) Focke respectively] were hybridised to analyse the inheritance mode of feeding preference. 2. Adult hybrid F₁ (A. viridicyanea female × A. fragariae male) preferred G. wilfordii to D. indica in two‐choice tests, regardless of which plant they had fed on as larvae. Adults of one backcross to A. fragariae preferred D. indica to G. wilfordii, and the two backcrosses to A. viridicyanea consumed only a very small percentage of D. indica. Adult females of F₂ showed no significant preference, whereas males of F₂ showed slight preference for G. wilfordii over D. indica. 3. Both the mean feeding preference and the segregation pattern of beetles indicate that the feeding preference of A. viridicyanea and A. fragariae for G. wilfordii and D. indica, respectively, is mainly controlled by a major dominant autosomal gene (or several genes). 4. The variance between feeding preference and oviposition preference of female F₂ indicate that the two behaviour traits of Altica species are controlled by different gene(s).     

Influence of foliar and systemically applied azadirachtin on host‐plant evaluation behaviour of the sweetpotato whitefly,Bemisia tabaci

Abstract The behaviour of female adult Bemisia tabaci is observed for a period of 20 min after initial contact with untreated cucumber leaves, or leaves either foliar or systemically treated with azadirachtin, to determine whether application of azadirachtin affects the host‐evaluation behaviour and whether the behaviour on treated leaves differs between application methods. Application of azadirachtin deters settling of the whiteflies on host plants. The whiteflies probe for shorter duration and less frequently but spend longer and engage more frequently in labial grooming on treated leaves than on untreated leaves. Behavioural transition between probing and other behavioural elements is less common, and that between labial grooming and other behavioural elements more common, on both treated leaves than on untreated leaves. No difference is detected in the host‐evaluation behaviour of B. tabaci between leaves foliar treated and systemically treated with azadirachtin.     

Recommendations for building out mosquito-transmitted diseases in sub-Saharan Africa: the DELIVER mnemonic

In sub-Saharan Africa, most transmission of mosquito-transmitted diseases, such as malaria or dengue, occurs within or around houses. Preventing mosquito house entry and reducing mosquito production around the home would help reduce the transmission of these diseases. Based on recent research, we make key recommendations for reducing the threat of mosquito-transmitted diseases through changes to the built environment. The mnemonic, DELIVER, recommends the following best practices: (i) Doors should be screened, self-closing and without surrounding gaps; (ii) Eaves, the space between the wall and roof, should be closed or screened; (iii) houses should be Lifted above the ground; (iv) Insecticide-treated nets should be used when sleeping in houses at night; (v) houses should be Ventilated, with at least two large-screened windows to facilitate airflow; (vi) Environmental management should be conducted regularly inside and around the home; and (vii) Roofs should be solid, rather than thatch. DELIVER is a package of interventions to be used in combination for maximum impact. Simple changes to the built environment will reduce exposure to mosquito-transmitted diseases and help keep regions free from these diseases after elimination.This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases''.     

Aggregation of helminths: the role of feeding behavior of fish hosts

Individual Arctic charr (Salvelinus alpinus) from Fjellfr?svatn, northern Norway, could be categorized by their stomach contents as zooplanktivores or benthivores. Feeding specialization among these fish was evident from negative correlations between helminths transmitted by pelagic copepods (Diphyllobothrium dendriticum and D. ditremum) and those transmitted by the benthic amphipod Gammarus lacustris (Cystidicola farionis and Cyathocephalus truncatus). Occurrences of parasite species acquired from the same types of invertebrate were positively correlated in the fish. Strong relationships among habitat use, diet, and helminth infections among the Arctic charr indicated persistent foraging patterns involving long-term habitat use and feeding specialization. The distribution of all parasite species was highly aggregated in the fish samples, measured by the exponent k of the fitted negative binomial distributions (range: 0.5-7.5) and the variance-to-mean ratios (s2/mean, range: 5-85). Charr specializing on either copepods or Gammarus predominantly contributed to high-intensity class intervals within the overall frequency distributions of the corresponding parasite species. Such fish had low infection intensities of helminths transmitted by other prey organisms. The detailed analyses of the parasite frequency distributions for fish with different habitat or feeding preferences evidently show how heterogeneity in trophic behavior contributes strongly to the commonly observed aggregation of helminths among hosts under natural conditions.     

成熟香蕉果实活性氧与乙烯形成酶活性的关系

香蕉果实成熟过程,随着活性氧产生速率从低水平→迅速跃升→高峰→下降的变化,其乙烯形成酶活性及乙烯产生也经历了基本同步的过程,显示了三者之间具有某种内在联系。外源超氧阴离子自由基（O2）能使乙烯形成酶（EFE）活性及乙烯产生出现跃升和高峰的时间明显提前;超氧歧化酶（SOD）则使EFE活性及乙烯产率明显下降。进一步说明了在香蕉果实成熟过程中,O2可能是引起EFE活性及乙烯产生迅速上升的原因之一,而过氧化氢（H2O2）则被证明与EFE活性及乙烯产生没有直接的关系。     

天花粉蛋白引起敏感细胞膜上G蛋白激活的初步研究

天花粉蛋白(Trichosanthin,TCS)是一种单链核糖体失活蛋白,具引产、抗肿瘤、抗HIV等多种生物学功能。天花粉蛋白专一性杀伤敏感细胞的机制一直未被研究清楚。本文首次以生物分子相互作用分析(BIA)证明在天花粉蛋白敏感的细胞膜上存在着能与天花粉蛋白专一结合的组分。我们进一步利用[~(35)S]GTPγS结合实验发现天花粉蛋白能够激活敏感细胞膜上的G蛋白,而对不敏感细胞没有相应的G蛋白激活。这些结果表明了在敏感细胞膜上天花粉蛋白特异受体的存在。     

单克隆非特异性抑制因子-β(MNSFβ)在大肠杆菌中的表达、抗体的制备及在小鼠子宫内膜上的组织定位

为了获得足够量的单克隆非特异性抑制因子-β蛋白(monoclonal nonspecific supressor factor β,MNSFβ)及其抗体用于探讨MNSFβ在着床中的作用机理,本研究构建了表达质粒pBV220/MNSFβ-hCGβ,在大肠杆菌中表达了融合蛋白MNSFβ-hCGβ,用抗hCGβ抗体对表达产物进行鉴定,结果表明融合蛋白MNSFβ-hCGβ得到了正确表达,且分子量和理论值相近。表达产物MNSFβ-hCGβ经初步纯化后用于免疫Balb/C小鼠,制备抗体。同时,我们还构建了表达质粒pGEX-4T-2/MNSFβ,在大肠杆菌中表达了融合蛋白GST-MNSFβ。用融合蛋白GST-MNSFβ对融合前的免疫小鼠回忆刺激并进行检测,制备了抗MNSFβ多克隆抗体和单克隆抗体。应用所制备的多克隆抗体进行免疫组化研究,对MNSFβ在小鼠子宫内膜上进行了组织定位,结果显示,MNSFβ在着床日(受精后第4.5天)小鼠子宫非着床位点的表达和着床位点相比明显提高。     

大鼠肠内容物细菌基因组DNA提取方法的比较

目的比较两种肠内容物前处理和两种提取方法对清洁级SD大鼠肠内容物细菌基因组DNA提取效率。方法分别选用PBS多次离心漂洗、液氮破细胞两种前处理方法和酚/氯仿抽提、试剂盒过柱法两种提取方法进行组合分析,对4份肠内容物和16份含金黄色葡萄球菌肠内容物进行随机提取。结果大鼠肠内容物细菌基因组DNA含量和纯度测定结果显示,与PBS反复离心相比,液氮研磨前处理能显著提高大鼠肠内容物基因组DNA。荧光定量PCR表明,液氮研磨前处理较PBS反复离心能更好地收集细菌基因组DNA,其Ct值最低。结论研究结果表明,采用液氮研磨试剂盒法在大鼠肠内容物DNA提取中是较为优良的方法,该方法为建立实验动物中微生物的定量PCR检测方法打下了基础。     

生长环境光强对夏蜡梅子叶显微形态结构和光合参数的影响

夏蜡梅子叶在一年生幼苗的成苗和生长过程中具有重要作用。为了解夏蜡梅子叶的光适应能力和机制,采用不同层数遮阳网遮光的方式,研究四种生长环境光强(4%、22%、50%和100%全光照)对夏蜡梅子叶显微形态结构和光合参数的影响。结果表明,随着生长环境光强的减弱,夏蜡梅子叶光饱和点(LSP)、光补偿点(LCP)、叶片厚度降低,叶绿素含量升高。在50%全光照下,子叶结构发育完全,细胞排列紧密,维管组织发达,最大净光合速率(Pmax)和暗呼吸速率最高(Rd);而低于22%全光照下子叶趋向于阴生叶结构。因此,夏蜡梅子叶具有较强的耐荫能力。