Direct in Vivo Intracellular Selection of Conformation-sensitive Antibody Domains Targeting Alzheimer's Amyloid-β Oligomers

The development of conformation-sensitive antibody domains targeting the misfolding beta amyloid (Aβ) peptide is of great interest for research into Alzheimer's disease (AD).We describe the direct selection, by the Intracellular Antibody Capture Technology (IACT), of a panel of anti-Aβ single chain Fv antibody fragments (scFvs), targeting pathologically relevant conformations of Aβ. A LexA-Aβ1-42 fusion protein was expressed in yeast cells, as the “intracellular antigen”. Two different scFv antibody libraries (Single Pot Libraries of Intracellular Antibodies, SPLINT) were used for the intracellular selections: (i) a naïve library, derived from a natural, non-immune, source of mouse antibody variable region (V) genes; and (ii) an immune library constructed from the repertoire of antibody V genes of Aβ-immunized mice. This led to the isolation of 18 different anti-Aβ scFvs, which bind Aβ both in the yeast cell, as well as in vitro, if used as purified recombinant proteins. Surprisingly, all the anti-Aβ scFvs isolated are conformation-sensitive, showing a high degree of specificity towards Aβ oligomers with respect to monomeric Aβ, while also displaying some degree of sequence-specificity, recognizing either the N-terminal or the C-terminal part of Aβ1-42; in particular, the scFvs selected from Aβ-immune SPLINT library show a relevant N-terminal epitope bias. Representative candidates from this panel of the anti-Aβ scFvs were shown to recognize in vivo-produced Aβ “deposits” in histological sections from human AD brains and to display good neutralization properties, significantly inhibiting Aβ oligomer-induced toxicity and synaptic binding of Aβ oligomers in neuronal cultured cells. The properties of these anti-Aβ antibody domains, as well as their direct availability for intra- or extra-cellular “genetic delivery” make them ideally suited for new experimental approaches to study and image the intracellular processing and trafficking of Aβ oligomers.     

Disturbance facilitates rapid range expansion of aspen into higher elevations of the Rocky Mountains under a warming climate

Aim Trembling aspen (Populus tremuloides Michx.) is absent in the upper foothills region of west‐central Alberta because of the cold conditions and short growing season at this high elevation. However, in recent years it appears that aspen has been establishing from seed in this zone and that it has been doing so mainly as a result of forest harvesting. The objectives of this study were to determine the frequency of and types of microsite required for the successful establishment of aspen seedlings at these higher elevations. Location Rocky Mountains Upper Foothills Natural Subregion of west‐central Alberta, Canada. Methods The current distribution of mature aspen and the presence and absence of aspen seedlings in harvested areas were determined in an area c. 300 km² in size, using ground and aerial surveys. In an intensive study, 12 belt transects (180 m long and 5 m wide) were established in areas disturbed by forest harvesting at high elevations where no aspen was present prior to harvesting. Transects were surveyed seven growing seasons after disturbance and the microsites occupied by aspen seedlings were characterized according to their substrate and microtopography. Similarly, the availability of different substrates and microtopographic positions were assessed by systematic point sampling on these sites. Results On level surfaces, aspen seedling regeneration was found up to 200 m higher in elevation than the mature aspen in the original undisturbed forests. Overall, there were 428 seedlings ha^?1 established on these transects, and the age distribution indicates that aspen seedlings had established in each of the seven growing seasons since the disturbance. Nearly all of the seedlings (93%) were established on mineral soil microsites and virtually no seedlings were established on undisturbed forest floor layers. Significantly more seedlings were found in concave microtopographic positions. Main conclusions This study indicates that aspen establishment from seed is currently not a stochastic event and demonstrates that aspen is rapidly expanding its range upslope in the Canadian Rocky Mountain region as a result of forest management practices that expose mineral soil substrates in conjunction with a warming climate. The change in canopy composition from conifer to deciduous forests at these higher elevations will have far‐reaching implications for ecosystem processes and functions.     

Recovery of Sasajiscymnus tsugae,released against hemlock woolly adelgid,Adelges tsugae,in the southern Appalachians

Eastern hemlock in the Great Smoky Mountains National Park is currently threatened by the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). As part of a management plan against this invasive insect pest, about 350,000 adults of the predatory beetle Sasajiscymnus tsugae (Sasaji and McClure) (Coleoptera: Coccinellidae) were released at ca. 150 sites in the Park from 2002 to 2007. Of these adult release sites, 33 were sampled in 2008 and 2009 using beat-sheet sampling for 4 man-hours. Sasajiscymnus tsugae adults (n=78) and/or larvae (n=145) were recovered from seven sites (21.2% of the release sites sampled). Recovery of S. tsugae was significantly associated with older release sites, with the most beetles recovered from 2002 release sites. These results indicate that S. tsugae may require more time (i.e., 5–7 years) than anticipated for population densities to reach readily detectable levels in some areas.     

长白山苔原带土壤动物群落结构及多样性

长白山苔原生态系统对环境变化非常敏感,一旦破坏很难恢复。土壤动物是陆地生态系统的重要组成部分,联系着地上和地下生态系统。为探讨长白山苔原带土壤动物群落的组成、结构和多样性特征,于2009年5月、7月和9月对上部和下部苔原带土壤动物进行了研究。研究表明:长白山整个苔原带土壤动物优势类群为甲螨亚目、节跳虫科和球角跳虫科。下部苔原亚带土壤动物个体数和类群数多,群落结构较为复杂。土壤动物的个体数随生境和时间变化有很大波动,类群数变化则较小。在7月份个体数最少,而类群数随着时间的变化有减少的趋势。土壤动物的垂直分布随时间和生境的不同而异。上部苔原亚带9月的甲螨亚目(P﹤0.01)、革螨亚目(P﹤0.05)及下部苔原亚带5月的甲螨亚目、革螨亚目、辐螨亚目(P=0.03,P=0.011,P=0.027)0—5 cm土层显著高于凋落物层;下部苔原亚带5月的球角跳虫科(P=0.001)及各月的节跳虫科和山跳虫科在各层之间存在显著差异(P=0.001,P=0.036,P=0.005,P=0.001,P=0.04,P=0.009)。两个亚带土壤动物多样性随时间的变化都有递减的趋势。土壤动物的多样性指数、丰富度指数和均匀度指数均是下部苔原亚带高于上部苔原亚带,而优势度指数则相反。相似性指数表明两个亚带土壤动物群落组成上存在一定的差异,各类群的相对数量差异在9月最大。下部苔原亚带的生境条件较适宜土壤动物生存,生物多样性较高。     

Eisfische – die etwas anderen Fische. Wirbeltiere ohne Blut?

Ice fish – the special fishes Ice fish lacks the oxygen‐binding haemoglobin. They do not transport oxygen in their blood by binding oxygen chemically but transport oxygen in physical solution. Their oxygen carrying capacity is less than 10% of ‘normal’ fish. They developed a number of adaptations in the evolution in order to survive successfully such as a much bigger heart, a larger blood volume and blood vessels exhibiting diameters substantially larger than in other fish. These adaptation partly compensate for the disadvantages arising out f the fact that oxygen is not bound chemically and thus be able to transport much less oxygen per unit of time than ‘normal’ fish. This article describes how ice fish have managed to compete with red‐blooded Antarctic fish and live in large numbers in the Southern Ocean.     

2001—2015年天山北坡植被覆盖动态变化研究

利用天山北坡2001—2015年植被生长比较旺盛月份(6—9月)的MODIS NDVI产品数据,结合像元二分法进行植被覆盖度提取,并对其空间分布特征、随时间及地形的动态变化和面积加权重心进行分析。研究表明:(1)天山北坡6—9月多年平均植被覆盖度介于0.4—0.5,以低、中低植被覆盖度为主,各等级植被覆盖度大致呈西北-东南向相间分布;(2)2001—2015年间,植被覆盖度有逐渐上升的趋势;植被覆盖改善区域(54.42%)大于退化区域(45.58%),西部较东部改善更为明显;植被覆盖度变异类型以弱变异和中等变异为主,植被覆盖度变化类型以稳定型为主;(3)天山北坡区域植被覆盖度变化受海拔高度影响明显:随着海拔高度的上升,较低植被覆盖度比例呈现先上升后下降再次上升趋势,较高植被覆盖度则与之相反;海拔3880 m以上低植被覆盖度占绝对优势,较高的植被覆盖度占比逐渐下降直至几乎绝迹;(4)各等级植被覆盖度面积加权重心集中在沙湾县、石河子市、玛纳斯县及呼图壁县;并呈现由集中到相对分散的趋势。     

贺兰山野化牦牛冬春季食性

2008年11-12月和2009年4-5月对贺兰山野化牦牛的冬季和春季食性进行了分析,在其分布的哈拉乌沟收集冬季粪样500 g,春季粪样498 g,利用粪便显微分析法分析贺兰山牦牛取食植物的种类组成和比例,结果表明,冬季牦牛取食11科20种(属)植物,主要取食禾本科(59.10%)和菊科(26.05%)植物,其中针茅(35.86%)、冷蒿(23.96%)、冰草(8.28%)、莎草(7.60%)、虎尾草(6.81%)、芦苇(6.58%)构成了冬季食物总量的89.09%,为冬季主要食物。春季取食植物11科21种(属)植物,主要取食禾本科(52.76%)和莎草科(18.80%)植物,其中针茅(22.72%)、莎草(18.80%)、冰草(13.23%)、狗尾草(9.93%)、唐松草(6.46%)、冷蒿(6.31%)占春季食物总量的77.45%,为春季主要食物。此外,冬春季均取食一定量的毛茛科和豆科植物。冬春季针茅都是贺兰山野化牦牛的大宗食物。冬季食物生态位宽度低于春季,而Shannon-Wiener指数和Pielou均匀度指数均高于春季。     

高黎贡山火尾绿鹛的鸣声特征分析

鸣声在鸟类通讯、配偶吸引和领域保卫等方面均有重要作用.本研究旨在探讨雀形目火尾绿鹛(Myzornis pyrrhoura)繁殖期的鸣声类型及其生物学意义.于2013和2014年的3至7月在云南高黎贡山片马垭口、独龙江垭口录制了成鸟(n = 30)、3个家庭的幼鸟(n = 6)和1巢雏鸟(n = 2)的鸣声.依据鸣声发出...     

气象因子对落叶松毛虫种群数量的影响

为探究落叶松毛虫种群数量与气象因子的关系,利用大兴安岭地区落叶松毛虫发生年度监测数据与气象数据构建线性回归模型,以赤池信息量准则为评价依据,通过逐步回归的方式从拟合优度和复杂度两方面权衡选取最优模型.采用相对权重法确定影响落叶松毛虫种群数量的关键气象因子,并量化了关键气象因子对松毛虫种群数量的影响.结果表明: 低龄幼虫期和繁殖期是影响落叶松毛虫种群数量的关键时期,而中龄幼虫期和高龄幼虫期的影响较弱; 低龄幼虫期日相对湿度均值、低龄幼虫越冬期日均温小于-22 ℃积温和繁殖期降水总量是影响落叶松毛虫种群数量的关键气象因子; 低龄幼虫期日相对湿度均值和繁殖期降水总量的标准差每增加1倍,落叶松毛虫种群数量的标准差分别减少62%和35%;低龄幼虫越冬期日均温小于-22 ℃积温的标准差每增加1倍,落叶松毛虫种群数量的标准差增加40%.表明全球气候变暖趋势下落叶松毛虫的爆发特点等可能呈现出新的形式,建立长期的种群数量监测体系尤为重要.