Using ecological trajectories to track long-term taxonomic and functional changes in benthic shallow soft-bottom communities (Bay of Saint-Brieuc,English Channel)

1. Taxonomic and functional trajectories of benthic assemblages were studied in shallow soft-bottom sediments in the bay of Saint-Brieuc (Western English Channel). Changes were assessed at different spatial and temporal scales using a macrobenthic dataset based on 38 stations sampled in 1987 and 2019, coupled with data from one station sampled annually between 2005 and 2019 as part of the European Water Framework Directive monitoring programme.
2. Taxonomic trajectories indicated 1) changes in the structure and distribution of benthic assemblages, 2) an homogenization of the assemblages, and 3) significant functional shifts.
3. Fishing activities and nutrient enrichment are probably strong drivers of the observed changes, as suggested by the higher mortality rate of fragile, flexible, tubiculous and burrowing species, and the increase in the abundance of opportunistic species in the assemblages. Certain populations of macroinvertebrates seem jointly controlled by climate change and by the aforementioned local factors of disturbance.
4. The Community Trajectory Analysis framework appears as a new and interesting method to track ecological changes in marine ecosystems by measuring change with respect to a baseline state, to help define ecological recovery (station returning to the initial ecological state) and departure (station presenting increased changes over time), and to analyse trajectory similarity.
5. According to the degradation of habitat over time, we identify the need for the implementation of knowledge-based conservation strategies, especially within Natura 2000 sites.

     

发情牛血清在猪卵母细胞成熟中的应用

为了检验发情牛(Bos taurus)血清在猪卵母细胞成熟中的应用,实验分别在成熟培养液中加入不同的血清,观察卵母细胞的成熟效果,并通过孤雌激活胚胎和重构胚的体外发育能力来判断血清对卵母细胞质量的影响:研究还进行了用发情牛血清成熟的卵母细胞构建的核移植胚胎的体内发育试验.结果表明,发情牛血清,成年牛血清和胎牛血清在猪卵母细胞的成熟率方面没有显著差异(P>0.05);卵母细胞成熟时加入不同的血清,对卵母细胞体外发育能力的影响不显著(P>0.05);来自含发情牛血清成熟液培养的卵母细胞,与胎儿成纤维细胞构建的克隆胚胎能够完成全期发育.     

Challenging conservation of migratory species: Sahelian rainfalls drive first-year survival of the vulnerable Lesser Kestrel Falco naumanni

In the context of attested global changes, accurate estimation of whether climatic fluctuations impact on population demographic parameters is needed for adequate management, especially for migratory species. We present a capture-recapture analysis linking survival rates of the vulnerable Lesser Kestrel (Falco naumanni) to annual rainfalls in the Sahel region, considered as a proxy of climatic conditions on wintering grounds. Recapture data were obtained from field observations of individuals ringed and sexed as juveniles over a 14-year monitoring period (1994-2007). We addressed a common but problematic situation in birds where: (i) sex is known with certainty for first-summer or older birds but only suspected for juveniles, and (ii) a large proportion of individuals never return to the study population (e.g. transient behavior). Transient behavior and unknown sexes were explicitly integrated considering a two age class in a multistate capture-recapture model. Survival was time-varying for juveniles (geometric mean: 0.499 ± 0.021) but constant - and higher - for adults (0.718 ± 0.013). Yearling survival probabilities were strongly correlated with rainfalls in the Sahel, suggesting a high dependence of juvenile upon the wintering conditions. While taking sex uncertainty into account, we detected no sex-dependence in survival. Incorporating the sensitivity of survival of wintering migratory birds to climatic variables such as precipitations in arid Sahelian ecosystem may allow to model conservation scenarios with a greater realism. Finally, we encourage the development of international management strategies for migratory species on wintering areas in addition to the existing conservation actions on summering Mediterranean grounds.     

城镇化进程中的粮食安全问题:一个研究综述

研究城镇化进程中的粮食安全问题,本质上是城镇化进程中产业之间的协调问题。中国的城镇化由于规模庞大、人口众多,使得城镇化是否影响粮食安全的研究一直伴随着国家城镇化水平的提升而从未间断过,特别是中国开始进入城镇化快速发展阶段之后。在简单回顾城镇化与粮食安全问题研究历史的基础上,通过着重梳理近十年来中国城镇化对粮食安全的研究文献,从城镇化影响粮食安全的因素和城镇化背景下保障粮食安全的解决方案两个角度的内容出发,指出了研究侧重点的发展变化。在影响因素问题上,研究者们从最初的侧重关注耕地减少,到探索农业生产技术应用提升农业生产力,再到保障劳动力的资源水平和满足粮食消费,越来越全面地认识城镇化对粮食安全的影响。而在解决方案上,从战略政策的演变,到夯实生产能力的策略变化,再到对海外资源依靠方式的转变,体现出不断完善的粮食安全保障体系建立。最后认为未来的研究可以在空间异质性、人力资本和制度要素变化上进一步深入。     

长江流域近期水沙变化趋势及成因分析

采用双累积曲线法分析了2000—2013年长江流域7大水文站水沙变化关系,基于Mann-kendall检验法和Yamamoto突变检验法研究水沙变化趋势和突变年份。结果表明,屏山、朱沱和寸滩站的双累积曲线较为顺直。宜昌、沙市、汉口和大通站则均在2005年发生转折,斜率减小,输沙量大幅减小;长江干流径流量的变化趋势较为平稳,发生突变的现象少,仅屏山站于2001—2002和2005—2006年发生突变,而输沙量的变化趋势则较为明显,常发生强突变现象,且宜昌、沙市、汉口和大通站均无虚假点出现;造成长江干流2000年以来输沙量显著减小的主要原因是三峡水库的蓄水运用和水土保持工作的持续开展,而降雨量下降是导致径流量减小的因素之一。     

Phenotypic variation in Azospirillum brasilense Sp7 does not influence plant growth promotion effects

The Azospirillum genus comprises free-living, plant growth-promoting, nitrogen-fixing bacteria found in the rhizosphere of plant roots. Azospirilla are able to promote plant growth mainly through improvement of root development. Bacterial surface components, such as extracellular polysaccharides and proteins, are involved in root colonization. Phase variation – or phenotypic variation – is one of the mechanisms by which microorganisms adapt to environmental changes. This phenomenon is characterized by the presence of a sub-population of the bacteria presenting a different phenotype relative to the major population. In this study we characterized phenotypic variation of Azospirillum brasilense Sp7. When plated on solid media, some A. brasilense colonies were shown to possess a much more mucoid morphology, producing 7.5–8 times more exopolysaccharide with different monosaccharide composition than the parental strain Sp7. The rate of appearance of this kind of variant colonies was 1 in 5000, in agreement with the accepted rate for the phase/phenotypic variation phenomenon. The variants were significantly more resistant to heat and UV-exposure than the parental strain and displayed genomic changes as seen by the different band patterns following ERIC-PCR, BOX-PCR and RAPD analyses. In plant inoculation experiments under greenhouse conditions, with maize, wheat, soybean and peanuts, the EPS overproducing variants performed as similar as the parental strain. Therefore, EPS overproduction did not confer an apparent advantage to A. brasilense in terms of induction of plant growth promotion.     

湖州市1998年迟中秋蚕血液型脓病暴发原因分析

分析了湖州市１９９８年迟中秋蚕血液型脓病暴发的原因，并提出了若干控制该病的对策。     

放射性肺纤维化大鼠动物模型的建立及其病变规律

用 60 Coγ射线对二级雌性 Wistar大鼠 (体重 ( 2 2 0± 2 0 ) g) 2 2 3只进行 30 Gy全胸单次照射 ,其中照射野为 4 .5cm× 4 .0 cm,照距为 3m,剂量率为 2 .7Gy/ min。分别于照后 3、7、1 4、2 1、2 8、4 2、56、70、90、1 80、2 70、36 5d共 1 2个时间点进行了取材观察。结果表明 ,肺脏病变初期呈急性变化 ,以后转为亚急性或慢性进行性发展过程 ,可大致分为 2个阶段 4个期。早期即急性炎症期或渗出期 ,中期为增生期 ,这 2期合为疾病的第 1阶段 ,称为放射性肺炎。后期即纤维化期 ,晚期即胶原化期 ,这 2期共同构成本病的第 2个阶段 ,称为进行性间质纤维化阶段     

不同地域柞蚕核型多角体病毒特性的研究

探讨了我国不同地域ApNPV的特征性状。试验表明:(1)不同地域的ApNPV对河南柞蚕、蓖麻蚕的致病性有差异;(2)不同地域ApNPV-DNA经EcoRI酶解,电泳图谱相似;使用salI内切酶酶解时,在琼脂糖电泳图谱中的C、G、O、Q、U和P等片段,不同毒株之间有差异;(3)河南云阳株(HY)病毒粒子多肽由16种蛋白亚基组成;病毒DNA为线形环状结构,周长4.76×10~5,计算DNA的分子量为:91.4×10~6道尔顿。     

实验性鸡马立克氏病羽髓病变研究

通过光镜1电镜等方法对鸡马立克氏病羽髓组织进行了形态学研究。结果显示，羽髓远端坏死，羽髓中有多量肿瘤细胞浸润，肿瘤细胞呈弥漫性或局部性浸润，电镜观察，肿瘤细胞核异型性明显，核膜凹陷，核内出现假核内包含物，在一些羽髓中，巨噬细胞吞噬肿瘤细胞较多见，而且观察到一些肿瘤细胞发生调亡，结果表明，鸡马立克氏病羽髓病变十分明显，羽髓的形态学变化可用于鸡马立克氏病的诊断。