广西边境地区活禽批发市场禽流感流行病学监测

为了给广西边境地区重大动物疫病防控阻截带建设提供数据支持,以及了解中越边境地区家禽禽流感病毒生态学,2012年12月—2017年12月,对广西边境地区主要活禽批发市场家禽及市场环境进行了系统监测。结果显示:广西边境地区活禽批发市场内禽流感病毒污染较重,呈多亚型病毒共存状态;家禽样品的平均病毒分离率为15.95%,环境样品则高达23.65%,明显高于家禽样品。市场调查发现:广西9个边境县(市、区)中,年活禽交易量在100万只以上的有5个;市场交易活禽主要为本地散养或规模场养殖家禽、从其他地区批发转运来的家禽以及边境走私家禽;大部分活禽市场没有配备消毒和无害化处理设施,也未严格执行休市制度。监测和调查结果表明,广西边境地区活禽批发市场家禽交易量大且频繁,来源复杂;市场中禽流感病毒污染严重,多亚型病毒在市场内常年蓄积循环,且存在家禽隐性带毒现象,因而有病毒散播风险。污染严重主要是因市场管理水平不高和生物安全措施不到位造成的,因此需要加强市场的动物卫生监管,提高禽流感监测力度。     

2017年湖南省部分猪场临床病例分析

为了解湖南省当前猪病的总体流行情况,对2017年湖南省13个市州72个规模化猪场和15个散养户送检的87例临床病例,进行了实验室诊断和流行病学分析。结果显示：该省猪群疫病多以散发形式出现,以高热、腹泻和呼吸道症状多见,气温偏低或偏高季节发病率较高,保育猪发病率高于其他生产阶段猪群,尤其是存栏量小的猪群;共检出11种病原,其中猪圆环病毒2型（PCV2）和高致病性猪繁殖与呼吸综合征病毒（HPPRRSV）检出率最高,且多以混合感染形式存在。结果表明,湖南省猪群中病毒感染较为广泛,PCV2和HPPRRSV是主要感染病原,在气温偏低和高温季节,要特别注意加强猪病防控。     

新一代温室气体排放情景下安徽省未来气候变化预估分析

基于联合国政府间气候变化专门委员会(IPCC)发布的新一代排放情景,和中国气象局发布的"中国地区气候变化预估数据集V3.0",针对安徽省,笔者选择1971—2000年作为基准期,采用区域气候模式模拟的方法,对比分析安徽省未来气候变化特征,重点评估近期内即未来20年气候变化趋势。模拟结果显示,未来20年不同情景下安徽省平均气温均为上升,全省平均增温幅度约0.9~1.1℃;而降水量变化具有不同特征,较低排放情景下降水量以上升为主,高排放情景则以下降为主。到2050s全省平均气温相比于基准期将升高1.6~1.7℃,升温幅度呈现北高南低的特征;全省降水量相比于基准期将下降50~90 mm,各地降水量均呈下降趋势。另外,通过对降水和气温的模拟,预估未来该地区旱涝演替更加频繁,高温热浪等事件也将进一步频发。     

Identification of organic acid-related genes and their expression profiles in two pear (Pyrus pyrifolia) cultivars with difference in predominant acid type at fruit ripening stage

‘Yandangxueli’ is a pear cultivar with predominant citric acid in the ripe fruit, different from most of pear cultivars such as ‘Gengtouqing’ in which malic acid is the predominant acid type. It was found that ‘Yandangxueli’ accumulated citric acid for three times against that in ‘Gengtouqing’ at fruit ripening stage. To investigate the mechanism of citric acid accumulation in ‘Yandangxueli’, organic acids content, gene expression and enzyme activity were studied in both cultivars. Five genes, Pp:mtCs, Pp:cyAco, Pp:cyIdh, Pp:mtMdh and Pp:cyMe which encoded citric synthase (CS), cytosolic aconitase (cyACO), NADP-dependent isocitrate dehydrogenase (NADP-IDH), NAD-dependent malate dehydrogenase (NAD-MDH) and NADP-dependent malic enzyme (NADP-ME) respectively, were identified from pear fruit. Their expression profiles and the corresponding enzyme activities were determined throughout fruit development in both cultivars. Results from these enzymes indicated that there were no strict relationship between gene expression, enzyme activity and citric acid accumulation. Expression analysis for two Py:vVAtp genes encoding vacuolar H⁺-ATPase A subunit and one Py:vVpp gene encoding Vacuolar H⁺-pyrophosphatase showed that they were all with up-regulated expression at the later development stage of ‘Yandangxueli’ but with down-regulated expression in ‘Gengtouqing’. Therefore, it is concluded that the different ability in citric acid transportation and storage might be involved in the high citric acid content in ‘Yandangxueli’.     

Rural land reforms and villagers' preferences for urban settlement: A case study of Shandong Province,China

Based on surveys conducted in Shandong Province, China, this paper examined the interests of rural residents to move to and settle in cities, as well as the factors that motivate or discourage their potential settlement changes. Results of the binary logistic regression analysis showed that villagers' urban settlement preference was related to sociodemographic factors such as gender, age, and occupation. Overall, the separation of the “three rights” (collective ownership, land contract right, and land use right) associated with rural land has strengthened the urban settlement preference of rural residents. Nevertheless, we did not find significant association between land transfer and the preference for urban settlement. For villagers who expressed interest in urban settlement, better job opportunities, education opportunities, and higher income are the leading “pull” factors that would attract them to cities. The attachment to rural life, high living costs, and high housing prices in cities were the top concerns for villagers who did not want to move. The study also found that villagers' desired urban destinations changed with the changing land parameters, indicating that the outcomes of China's rural land reforms may not be aligned well with the policy goals laid in the country's urbanization and rural development plans.     

Establishment of a comprehensive indicator system for the assessment of biodiversity and ecosystem services

Context

Common indicators are needed to monitor biodiversity loss and the implications for the sustainable provision of ecosystem services (ES). A plethora of different sets of indicators may hinder the identification of major endpoints for large-scale assessments of biodiversity and ecosystem services (BES).

Objectives

We aim to describe the main challenges of indicators for BES assessment and provide suggestions for establishing a comprehensive indicator system.

Methods

An extensive literature review was conducted in this study. We review the main challenges of indicators for BES assessment and propose corresponding improvements from our perspectives of theory and practical applications.

Results

The main theoretical challenges of existing indicators include inconsistent definitions and classifications of ES, misunderstanding of linkages among biodiversity, ecosystem structure, functions and services, and practical problems relate to such issues as indicator representativeness, data availability, and uncertainty. Our suggested improvements include clarifying the main terms, concepts and classification of indicators, establishing a robust conceptual framework with clear interactions among different components and indicators, selecting indicators based on ecosystem properties, streaming existing data into one platform, and strengthening validation of proxies. The steps for constructing a comprehensive indicator system for BES assessment are summarized.

Conclusions

Clear definitions of key terms are indispensable to classify indicators and construct a conceptual framework. Improved understanding of the relations among indicators of biodiversity, ecosystem functions, and ES across multiple scales can guide the development of the indicator system. The integrated indicator system is an important tool for BES assessment to support decision making for sustainable development.

     

果园间伐对梨叶片叶绿素荧光特性的影响

在15年生梨树高光效开心树形果园进行了间伐试验,测定并比较了间伐与未间伐果园梨树树体东、西侧叶片的叶绿素荧光参数,通过PSII的电子传递速率(ETR)、PSII的实际光合量子产量(Y(II))、调节性能量耗散的量子产量(Y(NPQ))以及非调节性能量耗散的量子产量(Y(NO))对光合有效辐射(PAR)的响应曲线,并得出PAR-ETR响应曲线的拟合参数。结果表明,与未间伐果园相比,成龄梨园间伐后梨树树体东、西侧叶片的ETR(最高可稳定至130μmol/(m2·s)左右)和Y(II)(最高可稳定至0.3左右)较高,Y(NPQ)较低(最低稳定在0.2左右),Y(NO)保持在一定范围内(0.5~0.7),且具有较高的最大电子传递速率(ETRmax)(最高可达152.4μmol/(m2·s)左右)、最小饱和光强(Ik)(最高可达510.3μmol/(m2·s)),表明间伐能够提高果园梨树叶片的光能利用效率。     

High-throughput screening reveals small molecule modulators inhibitory to Acidovorax citrulli

Acidovorax citrulli is a seed-transmitted gram-negative bacterium that can cause substantial economic yield loss in watermelon and melon production worldwide. Four small-molecule libraries containing 4,952 compounds were selected for high-throughput screening against A. citrulli wild-type strain Xu3-14 by evaluation of growth inhibition. One hundred and twenty-seven molecules (2.5% hit rate) were identified as bactericidal or bacteriostatic against A. citrulli at 100 μM. Secondary screens indicated that 27 candidate compounds were more effective against A. citrulli Group II strains than Group I strains (classified using repetitive element PCR). Several compounds were inhibitory to other pathogenic bacteria, including Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. campestris, but did not affect the growth of plant beneficial bacteria Pseudomonas fluorescens and Bacillus subtilis. More than half of the compounds did not inhibit germination of Arabidopsis or watermelon seeds. The effect of small molecules on A. citrulli seed-to-seedling transmission was evaluated by applying each compound to inoculated watermelon seeds and assessing seedling infection. Nine compounds were chosen for further investigation based on their reduction of percentage seedling infection and compiling scores on their specificity, sensitivity, and phytotoxicity obtained in the secondary screens. The five best compounds were selected (thiamphenicol, nadifloxacin, pipemidic acid, ciclopirox, and zinc pyrithione) for greenhouse tests and were found to effectively reduce the seed-to-seedling transmission of A. citrulli in both artificially and naturally infested seeds. These top five compounds provide a basis for future development of an A. citrulli-specific bactericide.