Brain modulation of Dufour’s gland ester biosynthesis in vitro in the honeybee (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Caste-specific pheromone biosynthesis is a prerequisite for reproductive skew in the honeybee. Nonetheless, this process is not hardwired but plastic, in that egg-laying workers produce a queen-like pheromone. Studies with Dufour’s gland pheromone revealed that, in vivo, workers’ gland biosynthesis matches the social status of the worker, i.e., sterile workers showed a worker-like pattern whereas fertile workers showed a queen-like pattern (production of the queen-specific esters). However, when incubated in vitro, the gland spontaneously exhibits the queen-like pattern, irrespective of its original worker type, prompting the notion that ester production in workers is under inhibitory control that is queen-dependent. We tested this hypothesis by exposing queen or worker Dufour’s glands in vitro to brain extracts of queens, queenright (sterile) workers and males. Unexpectedly, worker brain extracts activated the queen-like esters biosynthesis in workers’ Dufour’s gland. This stimulation was gender-specific; queen or worker brains demonstrated a stimulatory activity, but male brains did not. Queen gland could not be further stimulated. Bioassays with heated and filtered extracts indicate that the stimulatory brain factor is below 3,000 Da. We suggest that pheromone production in Dufour’s gland is under dual, negative–positive control. Under queenright conditions, the inhibitor is released and blocks ester biosynthesis, whereas under queenless conditions, the activator is released, activating ester biosynthesis in the gland. This is consistent with the hypothesis that queenright workers are unequivocally recognized as non-fertile, whereas queenless workers try to become “false queens” as part of the reproductive competition.     

Latitudinal variation in size of freshwater pulmonate mollusks (Mollusca: Gastropoda: Pulmonata) in Western Siberia

The size of shells in some freshwater pulmonate mollusk species abundant in Western Siberia (Lymnaea fragilis, L. terebra, Planorbis planorbis, and Anisus leucostoma) is relatively large in the south and decreases in the north. It is supposed that this phenomenon is explained by the fact that the season with conditions allowing the growth of mollusks is shorter in the north than in the south of Western Siberia.     

气田开发对生态环境的影响初探

西北干旱、半干旱地区气田开发可能对沙漠、荒漠等生态脆弱地区的生态环境造成一定的影响和破坏。本文通过采用点线结合,文件资料调研、现场调查并与3s技术相结合的方法。对地处干旱区的气田开发进行了生态环境影响初探。尤其对工程占地、土壤、植被、土地利用等因子做了进一步的分析,并提出了一些环境影响减缓措施与建议,这对做好气田环境保护工作具有一定的借鉴意义。     

山地景区生态足迹分析——以庐山为例

根据区域本底生态足迹和旅游生态足迹的计算模型,对庐山的生态足迹进行了分析计算,结果表明：(1)庐山生态足迹需求为0354 603 hm2,其中区域本底生态足迹为0343 510 hm2,旅游生态足迹为0011 093 hm2。(2)庐山可利用的人均生态承载力为0219 805 hm2,人均生态赤字达0123 543 hm2,其中旅游生态足迹占总赤字的313%。(3)在需求足迹结构中占9831%的化石能源地,大大超过了庐山的承载力面积,致使庐山的生态环境保护的压力不断加重。(4)庐山单位旅游生态足迹产值为33美元/hm2,其中单位旅游游览、旅游住宿和旅游购物的产值较高,旅游交通和旅游餐饮的单位产值相对较低,旅游产值还有较大的发展空间。(5)政府部门和社会各界必须推进更为系统化的无障碍旅游业,转变高能耗的经济发展道路,从而降低单位经济效益的生态足迹,实现庐山的可持续发展。     

黄柏河流域梯级水库沉积物磷形态特征及磷释放通量分析

为揭示黄柏河流域饮用水源水库的磷负荷特征,采用SMT分级方法对流域内3座梯级水库（玄庙观、天福庙、西北口水库）的沉积物磷形态特征及垂向变化特征进行了分析,并初步估算了沉积物-水界面正磷酸盐释放通量以及各形态磷含量对磷释放的影响.结果发现,沉积物总磷（TP）含量从流域上游至下游水库呈现递减趋势,平均值分别为（8070.0±2251.4）、（2681.2±1709.8）和（2656.6±1599.7）mg·kg^-1,均处于高度污染水平.3座水库中各个采样点磷形态之间的含量主要表现为：HCl-P > OP > NaOH-P.根据Fick第一定律,计算得到流域内3座梯级水库均表现为上覆水正磷酸盐的源,正磷酸盐释放通量从流域上游到下游水库呈现递减趋势,范围为0.0179~0.1825 mg·（m²·d）^-1.正磷酸盐释放通量与表层水体DO和叶绿素呈现正相关,与HCl-P,OP和TP同样表现为显著正相关.     

Empirical Estimation of Stream Discharge Using Channel Geometry in Low‐Gradient,Sand‐Bed Streams of the Southeastern Plains

Manning's equation is used widely to predict stream discharge (Q) from hydraulic variables when logistics constrain empirical measurements of in‐bank flow events. Uncertainty in Manning's roughness (n_M) is the major source of error in natural channels, and sand‐bed streams pose difficulties because flow resistance is affected by flow‐dependent bed configuration. Our study was designed to develop and validate models for estimating Q from channel geometry easily derived from cross‐sectional surveys and available GIS data. A database was compiled consisting of 484 Q measurements from 75 sand‐bed streams in Alabama, Georgia, South Carolina, North Carolina (Southeastern Plains), and Florida (Southern Coastal Plain), with six New Zealand streams included to develop statistical models to predict Q from hydraulic variables. Model error characteristics were estimated with leave‐one‐site‐out jackknifing. Independent data of 317 Q measurements from 55 Southeastern Plains streams indicated the model (Q = A_cR_H^0.6906S^0.1216; where A_c is the channel area, R_H is the hydraulic radius, and S is the bed slope) best predicted Q, based on Akaike's information criterion and root mean square error. Models also were developed from smaller Q range subsets to explore if subsets increased predictive ability, but error fit statistics suggested that these were not reasonable alternatives to the above equation. Thus, we recommend the above equation for predicting in‐bank Q of unbraided, sandy streams of the Southeastern Plains.     

新中国成立至改革开放前我国应对海洋灾害的实践及启示

梳理和总结新中国初期我国应对海洋灾害的实践,有助于我们了解海洋灾害的应对措施并为当今提供借鉴。通过对我国海洋灾害史料的分析和总结,得知从新中国成立至改革开放前这一时期内,"防重于救"是我国应对海洋灾害的的主要指导思想,在海洋灾害预测预警、建设防护性工程、群众自救和政府辅以必要救济等方面发挥了重要作用,并为之后我国应对海洋灾害打下了一定基础。     

Defining practical and robust study designs for interventions targeted at terrestrial mammalian predators

Conflicts between humans and mammalian predators are globally widespread and increasing, creating a long-lasting challenge for conservation and local livelihoods. Protection interventions, which are essential to conflict mitigation, should be based on solid evidence of effectiveness produced by robust study designs. Yet, it is unclear what study designs have been used in predator-targeted interventions and how they can be improved to provide best practices for replications. I examined how applications of five study designs (before-after, before-after-control-impact, control-impact, crossover [i.e., the same randomly assigned study units acting as treatments and controls during alternating trials], and randomized controlled trial) have changed over time and how these changes are related to authors, predator species, countries, and intervention types (aversion, husbandry, mixed interventions, invasive management, lethal control, and noninvasive management). I applied multinomial regression modeling to 434 cases (28 predator species and 45 countries) from 244 studies published from 1955 to 2020. Study design was related only to intervention type. Less reliable before-after and control-impact studies were the most common (47.7% and 38.2% of cases, respectively), and their use increased over years as did all interventions. The contribution of the most robust before-after-control-impact (7.4%), randomized controlled trial (5.3%), and crossover designs (1.4%) remained minor over time. Crossover is suitable for aversion, most husbandry techniques, and a few other interventions, but crossover interventions also have the most limitations in terms of applicability. Randomized controlled trial is generally applicable, but impractical or inappropriate for some interventions, and before-after-control-impact appears to be the most widely applicable study design for predator-targeted interventions.     

基于社交媒体建构的旅游演艺品牌符号研究--以《长恨歌》为例

运用内容分析法对《长恨歌》社交媒体的营销话语进行了梳理,并基于皮尔斯符号三元论,探究了旅游演艺在社交媒体平台中的品牌符号建构模式。结果发现:建构过程主要分为表征、传播和感知3个阶段,《长恨歌》品牌符号表征可划分为历史文化、知识信息、价值感知、环境服务和互动仪式5大主题,传播呈现时间同步性和空间异质性规律,旅游演艺品牌符号在激发受众多维感知的过程中,塑造出《长恨歌》深入人心、历久弥新的品牌形象,为社交媒体语境下旅游演艺品牌营销带来启示。     

习近平生态文明思想发展的历史溯源、发展脉络与世界意义

准确把握历史逻辑和深刻内涵是学习贯彻习近平生态文明思想的重要前提。本文从中国共产党实践、发扬马克思主义关于人与自然关系的思想视角,以百年时间轴为主线,回顾了中国共产党重视生态文明建设的历史和不同阶段特征,系统梳理了习近平生态文明思想的历史逻辑和理论体系,总结概括出我国生态文明建设取得的实践效果,并提出以习近平生态文明思想为引领,持续改善生态环境质量,推动形成绿色低碳发展全球共识,分享可持续发展中国方案的路径和趋势,共谋全球生态文明建设。