孤雌产雌生殖品系松毛虫赤眼蜂产卵强度对Wolbachia诱导的其生殖表型的影响

[目的]松毛虫赤眼蜂Trichogramma dendrolimi是一种用于鳞翅目害虫生物防治的重要卵期寄生蜂.本研究旨在明确孤雌产雌生殖品系松毛虫赤眼蜂的产卵强度对其体内Wolbachia滴度及Wolbachia诱导的孤雌产雌生殖表型的影响.[方法]在室内调查了3个处理组松毛虫赤眼蜂雌蜂不同产卵强度(每日仅1 h供寄...     

Effects of disturbances on aboveground biomass of alpine meadow in the Yellow River Source Zone,Western China

A field experiment quantifies the impacts of two external disturbances (mowing‐simulated grazing and number of pika) on aboveground biomass (AGB) in the Yellow River Source Zone from 2018 to 2020. AGB was estimated from drone images for 27 plots subject to three levels of each disturbance (none, moderate, and severe). The three mowing severities bear a close relationship with AGB and its annual change. The effects of pika disturbance on AGB change were overwhelmed by the significantly different AGB at different mowing severities (−.471 < r < −.368), but can still be identified by inspecting each mowing intensity (−.884 < r < −.626). The impact of severe mowing on AGB loss was more profound than that of severe pika disturbance in heavily disturbed plots, and the joint effects of both severe disturbances had the most impacts on AGB loss. However, pika disturbance made little difference to AGB change in the moderate and non‐mowed plots. Mowing intensity weakens the relationship between pika population and AGB change, but pika disturbance hardly affects the relationship between mowing severity and AGB change. The effects of both disturbances on AGB were further complexified by the change in monthly mean temperature. Results indicate that reducing mowing intensity is more effective than controlling pika population in efforts to achieve sustainable grazing of heavily disturbed grassland.     

温光对稻米蛋白质及氨基酸含量的影响

研究水稻结实期的温、光条件对稻米蛋白质与氨基酸含量的影响,其结果表明：同一品种作为早季栽培时,稻米氨基酸含量比作晚季栽培时低,分期播种时,以结实期日平均气温为２４℃时蛋白质含量为最高;不同海拔高度种植时,以８００ｍ处蛋白质含量为最高;结实期人工高温处理,稻米蛋白质和氨基酸含量降低,低温（２１／２０℃）处理时,粳稻的氨基酸含量增加而籼稻则有所降低,籼稻氨基酸形成的适温在２４￣２６℃之间,弱光下,糙米     

三江平原湿地保护区内外的生态功能差异

湿地保护区是一类特殊的陆地保护区,其保护效果不仅取决于内部的管理强度,还受到其周边地区水文状况的强烈影响,因此保护区内外生态功能的差异程度是评价其保护效果的一个综合性指标.根据三江平原建三江管局2004年Landsat-TM影像解译的土地利用图以及2002年1∶50000数字高程(DEM)数据,利用基于Arcview3.2软件的SWAT水文模型获得各湿地保护区的汇水区作为其水文敏感区.在此基础上,利用专家咨询和有关湿地生态系统服务功能价值的研究结果,计算出各湿地保护区及其水文敏感区的湿地生态功能指数.结果表明,国家级保护区的湿地生态功能普遍优于地方级保护区,而其水文敏感区的湿地生态功能则并不一定优于地方级保护区的水文敏感区.通过对各保护区及其水文敏感区的湿地生态功能指数相对值进行聚类分析和相关分析可知,位于浓江-别拉洪河流域且毗邻的几个保护区的湿地生态功能相对状况较为接近,地方级保护区与其水文敏感区的湿地生态功能指数之间存在高度正相关.这充分说明湿地保护区的管理强度很大程度上决定了其保护效果.     

腺苷减少豚鼠心室肌细胞内游离钙浓度

目的：研究腺苷对豚鼠心室肌细胞内游离钙浓度（[Ca^2＋]i）的影响并探讨其可能机制。方法：用激光共聚焦显微镜探测细胞内游离钙浓度,结果用相对荧光强度（（FI-FI0）／FI0,％;FI0：对照;FI：给药）表示。结果：①在正常台氏液和无钙台氏液中,腺苷（10,50,100μmol／L）浓度依赖性地降低[Ca^2＋];。②含30mmol／L KCl的台氏液（高钾台氏液）能够增加[Ca^2＋]i。腺苷（10,50,100μmol／L）能够显著抑制KCl引起的[Ca^2＋]i的增加。③预先应用选择性腺苷AI受体拮抗剂DPCPX（1μmol／L）,可大部分取消腺苷（100μmol／L）在高钾台氏液中的作用。腺苷（100μmol／L）在高钾台氏液的作用也可被预先应用一氧化氮（No）合酶抑制剂L-NAME（1mmol／L）所部分减弱。④腺苷（100μmol／L）能明显抑制无钙台氏液中由低浓度ryanodine引起的[Ca^2＋];增加。⑤当细胞外液钙浓度由1mmol／L增加到10mmol／L而诱发心室肌细胞钙超载时,部分心室肌细胞产生可传播的钙波,腺苷（100μmol／L）可降低钙波发生的频率和持续时间,最终阻断钙波并降低[Ca^2＋];。结论：腺苷可通过抑制外钙内流和减少肌浆网内钙释放从而降低[Ca^2＋],其减少外钙内流可能是由于腺苷A1受体介导的电压依赖性Ca^2＋通道的抑制,NO可能参与这一过程。     

Ecophysiological responses of two poplar species to intraspecific and interspecific competition under different nitrogen levels

美洲黑杨(Populus deltoides)和欧美杨(P. euramericana)在中国是广泛应用的造林树种。目前,有关这两种树种在纯林和混栽林条件下对氮缺乏的响应研究还较少。本研究的目的是分析这两种植物在不同竞争条件及氮水平下的生长,形态及生理响应。以美洲黑杨和欧美杨为研究材料,以盆栽实验模拟不同竞争方式(美洲黑杨×美洲黑杨,种内竞争;欧美杨×欧美杨,种内竞争;美洲黑杨×欧美杨,种间竞争),研究不同竞争方式和氮水平(正常氮添加和氮缺乏)对两种植物特征的影响,分析其在竞争和氮缺乏条件下生长,形态及生理特性的 变化。研究结果表明,在正常氮素水平下,与种内竞争相比,种间竞争显著降低了欧美杨的根重、根分配、根冠比、碳氮比,增加了其叶重、叶分配以及总叶面积;同时除了细根重、根冠比、比叶面积、根分配、总氮含量和碳氮比未受影响外,种间竞争也显著影响了美洲黑杨的生长和形态特征。此外,在正常氮水平下,美洲黑杨的叶绿素a含量、总叶绿素含量、类胡萝卜素含量以及碳同位素组成在种间竞争条件下都显著低于种内竞争,但是在欧美杨中未发现显著的种间和种内竞争差异。在种内竞争下,氮缺乏对美洲黑杨的影响比在种间竞争下更强;但对于欧美杨,氮缺乏的影响在两种竞争条件下差异并不显著。因此,在正常氮素水平下,美洲黑杨纯林栽培比与欧美杨混合栽培生长表现更好;但在氮素缺乏时,欧美杨在纯林和混合栽培条件下的表现比美洲黑杨更稳定。     

Comparing measures of breeding inequality and opportunity for selection with sexual selection on a quantitative character in bighorn rams

The reliability and consistency of the many measures proposed to quantify sexual selection have been questioned for decades. Realized selection on quantitative characters measured by the selection differential i was approximated by metrics based on variance in breeding success, using either the opportunity for sexual selection I_s or indices of inequality. There is no consensus about which metric best approximates realized selection on sexual characters. Recently, the opportunity for selection on character mean OSM was proposed to quantify the maximum potential selection on characters. Using 21 years of data on bighorn sheep (Ovis canadensis), we investigated the correlations between seven indices of inequality, I_s, OSM and i on horn length of males. Bighorn sheep are ideal for this comparison because they are highly polygynous and sexually dimorphic, ram horn length is under strong sexual selection, and we have detailed knowledge of individual breeding success. Different metrics provided conflicting information, potentially leading to spurious conclusions about selection patterns. I_δ, an index of breeding inequality, and, to a lesser extent, I_s showed the highest correlation with i on horn length, suggesting that these indices document breeding inequality in a selection context. OSM on horn length was strongly correlated with i, I_s and indices of inequality. By integrating information on both realized sexual selection and breeding inequality, OSM appeared to be the best proxy of sexual selection and may be best suited to explore its ecological bases.     

Agricultural system transitions in selected Indian states: What do the related indicators say about the underlying biodiversity changes and economic trade-offs?

The article describes the land use system transition dynamics in selected states in India and discusses its underlying biodiversity impacts and economic driving forces. The concept of system transition is described as a continuum between forests and highly intensive agriculture via different grades of intensification where profit differential is identified as the system transition pressure. In order to operationalise the concept, the article develops land use suitability, input use intensity and farming system diversity indices which are calculated for different agricultural cropping systems in the selected states of India. The results show the apparent decline in land use suitability, reduction in farming system diversity, increase of cultivation intensity, reflecting a reduction in planned and associated agro-biodiversity. The results also show increasing transition pressure to shift from low intensive and high diverse systems to high intensive low diverse systems that represent increasing opportunity cost of conservation of the former systems. A set of policy measures to deflate the transition pressure that can at least retain a threshold of traditional high diversity systems are briefly discussed. The study also outlines further research directions.     

Measurement and calculation of carbon intensity based on ImPACT model and scenario analysis: A case of three regions of Jiangsu province

In order to find the best approach to achieving the carbon intensity reduction targets of Jiangsu province, we used an ImPACT model to undertake a scenario analysis of the economic development, population size, energy intensity, and energy consumption structure of three regions of Jiangsu province. Based on carbon intensity reduction targets of 40% and 45%, the carbon intensity in different scenarios for 2015 and 2020 were calculated in order to find the optimum emission reduction scenarios for the three regions of Jiangsu province. The research results suggest the following. Only the northern and southern regions of Jiangsu province can achieve the 40–45% reduction target for carbon intensity in 2020 in all of the scenarios. The northern regions of Jiangsu province have a minimum carbon intensity of 0.525414 tons per ten thousand yuan in the scenarios where the economic development and population size are at a medium rate of increase and the energy intensity and energy consumption structure are at a high rate of change. The middle regions of Jiangsu province have a minimum carbon intensity of 0.566539 tons per ten thousand yuan in the scenarios where the economic development is at a high rate of increase and the energy intensity and energy consumption are at a high rate of change. The southern regions of Jiangsu province have a minimum carbon intensity of 0.613281 tons per ten thousand yuan in the scenarios where the energy intensity and energy consumption structure are at a high rate of change. On the basis of these findings, this study developed relevant policies and suggestions.