Honey bee nest thermoregulation: diversity promotes stability

A honey bee colony is characterized by high genetic diversity among its workers, generated by high levels of multiple mating by its queen. Few clear benefits of this genetic diversity are known. Here we show that brood nest temperatures in genetically diverse colonies (i.e., those sired by several males) tend to be more stable than in genetically uniform ones (i.e., those sired by one male). One reason this increased stability arises is because genetically determined diversity in workers' temperature response thresholds modulates the hive-ventilating behavior of individual workers, preventing excessive colony-level responses to temperature fluctuations.     

Honey bee recruitment to food sources: olfaction or language?

Honey bee recruits locate food sources by olfaction and not by use of distance and direction information contained in the recruitment dance. Recruitment efficiency increases as odor of the food source accumulates in the hive, from hour to hour and from day to day. Flight patterns, landing patterns, bee odor, and Nassanoff secretion apparently do not aid in recruitment of bees.     

生态条件的多样性变化对蜜蜂生存的影响

目的在云南省罗平县油菜花期,比较西方蜜蜂不同放蜂密度下东方蜜蜂采集行为的变化,以期从食物资源竞争的角度为合理保护中国本土蜂种和维持植物群落结构及其稳定性提供科学依据。方法调查九龙镇和大水井乡主干道上的西方蜜蜂放蜂密度,根据放蜂密度选择6个试验点放置供试东方蜜蜂蜂群;观测试验点农田、山林两种生境中访花的东方蜜蜂和西方蜜蜂数量以及东方蜜蜂访花频率、单花采集停留时间;调查试验点周围3 km内的显花植物种类,采集植物花粉与东方蜜蜂花粉团,计算蜂花粉团中不同花粉的比例;分析西方蜜蜂不同放蜂密度对东方蜜蜂采集行为和粉源植物利用的影响。结果油菜盛花期,山林中访花的东方蜜蜂数量比例大于农田样方;油菜末花期,西方蜜蜂蜂场大量撤离后,农田样方中访花的东方蜜蜂数量比例明显增加;农田样方中东方蜜蜂的平均访花频率与其周围3 km范围内的西方蜜蜂数量(密度)呈显著的正相关关系,单花采集停留时间与其周围3 km范围内的西方蜜蜂数量(密度)呈显著的负相关关系;山林生境中西方蜜蜂放蜂密度大的试验点,东方蜜蜂的访花频率高,单花采集停留时间短;各试验点东方蜜蜂采集的花粉团总数量与其周围3 km范围内的西方蜜蜂数量(密度)呈负相关关系;油菜花期东方蜜蜂采食零星粉源植物花粉的比例与其周围3 km范围内的西方蜜蜂数量(密度)呈显著的正相关关系。结论西方蜜蜂放蜂密度对东方蜜蜂的采集行为有显著影响,且西方蜜蜂放蜂密度越大,东方蜜蜂的食物生态位越偏离农田中的大宗蜜源(油菜),其采集区域朝着山林转移的趋势越明显。     

Canopy orientation: a new kind of orientation in ants

Celestial cues, such as the sun or patterns of polarized sky light, appear to have no detectable effect in the precise homing orientation of foragers of Paltothyreus tarsatus. Field and laboratory experiments reveal that canopy patterns are a major influence in the home range orientation of this ponerine ant, a common species in African forests. Canopy orientation appears to be well suited to the restrictive lighting conditions of tropical forests.     

Bird orientation: a method of study

A psychophysical technique has been applied to the study of bird orientation. The technique enables precise determinations of the accuracy with which a bird can orient itself. Data indicate that a pigeon can detect angular displacement as little as 3.4 degrees.     

Chemical trail-following by flying insects: a mechanism for orientation to a distant odor source

An aerial trail of odorous pheromone molecules extends downwind from a female pink bollworm moth that is receptive for mating. Males apparently sense the boundaries of the trail during their characteristic zigzag flights across it. Contrary to previous beliefs, the mechanism by which the males steer toward the odor source does not require a sensing of wind direction.     

五倍子蜂蜜TaqMan探针实时荧光定量PCR检测方法的建立

为五倍子蜂蜜的鉴定检测提供技术支撑,利用TaqMan探针实时荧光定量PCR技术,以五倍子树基因组中ITS基因为靶序列,设计并筛选出特异性引物探针,通过特异性、灵敏度和重复性等试验,建立五倍子蜂蜜TaqMan探针实时荧光PCR检测方法。结果表明:建立的方法特异性良好,生成的标准曲线有良好的线性关系,相关系数(R2)为0.998,最低检测限为0.2pg DNA/反应。该方法特异性强、灵敏度高、结果可靠。     

以人为本:高校课程建设的价值取向

高校课程是为人而设、由人而为的实践活动。强调生命回归与主体意识,整合人文素养与科学精神,超越固定课程内容,实行人性化管理,是高校课程建设的题中应有之义。     

我所在科技体制改革中的职能定位与发展取向

广东省科技体制改革在全国各省中先行了一步 ,广东省农科院科技情报研究所已转为咨询服务类的科技企业。该所按照改革的要求 ,结合自身的特点 ,对原有职能进行重新定位 ,在企业化的道路上进行探索和实践。本文简要地介绍该所实行企业化改革的实践和取得的主要效果     

为创新教育服务:研究生课程改革的重要方向

研究生课程教学是研究生培养的重要环节,创新型国家的建设,对研究生的课程建设如何为创新教育服务提出了新的要求。在对研究生课程改革的动力机制、理论和现实基础进行系统研究的基础上,提出了研究生课程改革的方向和基本思路。     

Glycosylphosphatidylinositol: a candidate system for interleukin-2 signal transduction

The mechanism of interleukin-2 (IL-2) signal transduction was analyzed by use of an inducible B lymphoma. Like normal antigen-activated B lymphocytes, the lymphoma cells respond to IL-2 by proliferating and differentiating into antibody-secreting cells; both responses are blocked by a second interleukin, IL-4. Analyses of the signaling pathway showed that IL-2 stimulated the rapid hydrolysis of an inositol-containing glycolipid to yield two possible second messengers, a myristylated diacylglycerol and an inositol phosphate-glycan. The myristylated diacylglycerol response exhibited the same IL-2 dose dependence as the growth and differentiative responses, and the generation of both hydrolysis products was inhibited by IL-4. These correlations implicate the glycosyl-phosphatidylinositol system in the intracellular relay of the IL-2 signal.     

基于四交群体的玉米叶夹角和叶向值QTL定位分析

选育耐密紧凑株型是增加玉米单位面积产量的重要途径之一,而叶夹角和叶向值是衡量株型的重要参数。本研究选用叶夹角和叶向值存在差异的玉米自交系郑58、PH6WC、87-1和自330构建1个四交(郑58/豫87-1//PH6WC/自330)组合,以228个四交F1单株为作图群体,构建了1张含225个SSR位点,全长1 387.2cM的玉米分子标记遗传连锁图谱,标记间平均间距为6.19cM。基于四交群体应用区间作图法检测4个环境下的QTL,共检测到13个叶夹角相关QTL,分别位于第1、2、3、4、5、7和10染色体上,单个QTL可解释5.1%~20.0%的表型变异;检测到15个叶向值相关QTL,分别位于第1、2、4、5、7、8和9染色体上,单个QTL可解释5.4%~20.1%的表型变异。其中qLA-E2-2和qLA-E4-2落在同一标记区间umc1692-umc2297(bin 5.03),分别解释16.6%和13.2%的表型变异;qLO-E1-1、qLO-E3-2和qLA-E4-1落在同一标记区间umc1568-bnlg1953(bin1.02),分别解释10.1%、19.9%和12.3%的表型变异;qLO-E2-1和qLO-E3-1落在同一标记区间phi056-phi427913(bin 1.01),分别解释13.8%和10.0%的表型变异。这些多个环境共同检测到的QTL将为玉米耐密理想株型育种中叶夹角叶向值的分子标记辅助选择提供有益信息,加速耐密株型玉米品种的选育。     

Dictyostelium discoideum: a model system for cell-cell interactions in development

The cellular slime mold Dictyostelium discoideum undergoes a transition from single-celled amoebae to a multicellular organism as a natural part of its life cycle. A method of cell-cell signaling that controls chemotaxis, morphogenesis, and gene expression has developed in this organism, and a detailed understanding of this signaling system provides clues to mechanisms of intercellular communication in the development of metazoans.     

Innovation of the double-maize cropping system based on cultivar growing degree days for adapting to changing weather conditions in the North China Plain

Double-maize cropping system is an effective option for coping with climate change in the North China Plain. However, the effects of changes in climate on the growth and yield of maize in the two seasons are poorly understood. Forty-six cultivars of maize with different requirements for growing degree days (GDD), categorized as high (H), medium (M) or low (L), and three cultivar combinations for two seasons as LH (using JD27 and DMY1 from category L in the first season; and YD629 and XD22 from category H in the second season), MM (using JX1 and LC3 from category M in the first season; and ZD958 and JX1 from category M in the second season) and HL (using CD30 and QY9 from category H in the first season; and XK10 and DMY3 from category L in the second season) were tested to examine the eco-physiological determinants of maize yield from 2015 to 2017. The correlations between the combinations of cultivars and grain yield were examined. The combination LH produced the highest annual grain yield and total biomass, regardless of the year. It was followed, in decreasing order, by MM and HL. Higher grain yield and biomass in LH were mainly due to the greater grain yield and biomass in the second season, which were influenced mainly by the lengths of the pre- and post-silking periods and the rate of plant growth (PGR). Temperature was the primary factor that influenced dry matter accumulation. In the first season, low temperatures during pre-silking decreased both the duration and PGR in LH, whereas high temperatures during post-silking decreased the PGR in MM and HL, resulting in no significant differences in biomass being observed among the three combinations. In the second season, high temperatures decreased both the PGR and pre- and post-silking duration in MM and HL, and consequently, the biomass of those two combinations were lower than that in LH. Moreover, because of lower GDD and radiation in the first season and higher grain yield in the second season, production efficiency of temperature and radiation (R_a) was the highest in LH. More importantly, differences in temperature and radiation in the two seasons significantly affected the rate and duration of growth in maize, and thereby affecting both dry matter and grain yield. Our study indicated that the combination of LH is the best for optimizing the double-maize system under changing climatic conditions in the North China Plain.     

Amazon basin: a system in equilibrium

Despite the very active deforestation of the last decade, the Amazon Basin is still primarily covered with trees and is a system in equilibrium. The Andes form a barrier at the western end of the basin and, coupled with the prevailing easterly winds, ensure an almost unique precipitation and water-recycling regime. On average 50 percent of the precipitation is recycled, and in some areas even more. The soils are poor. Most of the nitrogen and phosphorus is found in the soil, and the remaining nutrient elements are found in the standing biomass. There is some nutrient recycling and little loss from the intact ecosystem, and the small input of nutrients from precipitation maintains a small positive nutrient balance. Continued large-scale deforestation is likely to lead to increased erosion and water runoff with initial flooding in the lower Amazon, together with reduced evapotranspiration and ultimately reduced precipitation. Reduced precipitation in the Amazon could increase the tendency toward continentality and adversely affect climate and the present agriculture in south-central Brazil.     

Pollination by ants: a low-energy system

Polygonum cascadense, a small, apparently self-incompatible, annual plant, is regularly cross-pollinated by the ant Formica argentea. Comparison of other purported ant-pollinated plants with traits favoring such pollination suggests that some, but not all, may be ant pollinated. Ant-pollination interactions are characterized by low expenditure of energy by both ant and plant.