Association between the mollusc bivalve Loripes lucinalis and a Chlamydia-like organism,with comments on its pathogenic impact,life cycle and possible mode of transmission

Loripes lucinalis is a littoral bivalve which has already been confirmed to harbour endo-cellular sulfur-oxidizing bacteria within its gills. Examination of the digestive gland of L. lucinalis collected from the Moulin Blanc Beach in the Bay of Brest (Brittany, France) revealed the existence of an additional association involving a Chlamydia-like organism. Three different forms of Chlamydia-like bacteria were observed: reticulate rod-shaped cells, electron-dense cells and enlarged cells. The reticulate rod-shaped cells and the electron-dense bodies are thought to represent the germinal initial body and infectious form of the bacteria, respectively. The enlarged cells were always associated with what are believed to be spherical or icosahedral phages. Initial infestation seems to occur by phagocytosis at the apical pole of the digestive cells of the tubule and duct epithelia. Within the host cell, the bacteria undergo binary fission and budding, forming an inclusion which gradually fills up the cell. Inclusions are generally between 15 and 30 m in size, and > 85% of all individuals examined possessed inclusion bodies. The level of infestation varied between individuals, some being heavily colonized, but did not seem to be related to season. Histological and ultrastructural observations suggest that, once developed, the colony has three possible fates: (1) the cells will degenerate due to phage infection; (2) colony overcrowding will occur, causing the development of electron-dense bodies that will be released into the lumen; (3) the entire membrane-bound inclusion will be released into the lumen and subsequently into the pallial cavity. Inclusions within the pallial cavity may be ingested by the host or may even be phagocytized by bacteriocyte cells of the gill. It is proposed that this association could be a form of symbiosis and that L. lucinalis may, therefore, be a rare example of an organism adapted to harbour two very different symbioses.     

Fas/FasL途径在氟暴露致PC12细胞凋亡中的作用

为了探讨Fas/FasL途径在氟暴露致PC12细胞凋亡中的作用及其机制,采用含20、40、80、160mg/L NaF培养液处理PC12细胞.结果表明,所有剂量Na F处理12、24、36、48h,PC12细胞活性升高;上述不同剂量Na F处理24h后,与对照组比,PC12细胞的活性氧水平、细胞凋亡率、细胞内Fas/FasL信号转导通路Fas和Fas L、Caspase8、FADD、Caspase3基因和蛋白表达水平均呈显著上升(P<0.05),而Bid基因和蛋白表达水平显著下降(P<0.05),且呈氟暴露剂量依赖性.结果提示Fas/FasL途径在氟暴露致PC12细胞凋亡中起重要作用,其中FADD可能是Fas/FasL凋亡途径中的重要靶分子.     

紫外分光光度法测定海水中石油类的不确定度评定

对紫外分光光度法测定海水中石油类浓度进行了不确定度评定。通过对标准溶液、标准工作曲线拟合、前处理过程等影响测定结果的不确定度分量进行分析,计算出测定结果的扩展不确定度,并找出影响该不确定度的主要因素。结果表明,紫外分光光度法测定海水中石油类浓度的不确定度的主要来源是实验中前处理过程的不确定度,本次实验所测海水中石油类浓度的不确定度报告为19.98±1.326 mg/L。     

BDD电极电化学氧化降解废乳化液

废乳化液是机械加工过程产生的一种高浓度有机废液,属于危险废物。通过实验研究了BDD电极电化学氧化处理废乳化液的降解效果,考察了电流密度、电解质种类及浓度、初始pH值和反应温度对降解效率的影响。结果表明:BDD电极电化学氧化可有效降解废乳化液中的有机物,当采用Na₂S₂O₈为电解质,电流密度超过60 mA/cm²时,降解4 h后COD降解率达到99%以上,单位质量(1 kg)COD降解能耗最大,约25 kW·h/kg。电流密度由20 mA/cm²增加至60 mA/cm²时,COD去除率可提高13%左右,单位能耗也会随之增加;电流密度为60 mA/cm²时,采用Na₂S₂O₈作为支持电解质降解2 h, COD降解率比NaCl和Na₂SO₄作为电解质高10%以上;提高反应温度和保持酸性条件均有利于增强COD降解效果。动力学分析表明:BDD电极电化学氧化降解废乳化液的过程符合一级反应动力学方程,电流密度<60 mA/cm²时,一级反应动力学常数k与电流密度基本呈线性关系。     

基于生态系统服务簇的生态功能区权衡与协同关系演变：以吐哈地区为例

明确生态功能区的空间分布和组成结构,了解多种生态系统之间的权衡与协同关系的演变规律,对吐哈地区生态系统的科学管理和修复至关重要.研究旨在探索各生态系统服务簇的权衡协同关系,并根据生态特征制定差异化的生态管理策略.基于InVEST模型和价值当量法估算吐哈地区2000~2020年6种生态系统服务,即固碳量、产水量、土壤保持、生境质量、粮食生产和美学景观.通过计算多种生态系统服务景观指数（MESLI）量化不同区域的多种生态系统服务综合能力.使用SOFM算法识别生态系统服务簇,确定区域主导服务功能并划分生态功能区.最后,采用Spearman相关分析方法探究全域以及不同服务簇内各生态系统服务之间的权衡协同效应.结果表明：①2000~2020年,吐哈地区建设用地、耕地、水域和林地面积增长,其中建设用地增幅最大,草地和未利用土地的面积持续减少.②产水量、生境质量、土壤保持、美学景观、固碳量和粮食生产呈“北高南低”的空间分布格局,粮食生产高值区主要分布在山前平原绿洲内耕地区域.2000~2020年,固碳量和粮食生产年均值先增后减,美学景观先减后增,产水量逐年上升,土壤保持逐渐下降,2020年生境质量出现轻微下降.③MESLI值多年平均值为0.49,表明地区整体提供各种生态系统服务的能力较弱,生态系统结构的完整性较低.MESLI整体呈“中、西高,南低”的空间格局,具有明显的空间分异性.地区以低MESLI值为主,占总面积的79.46%.④识别出4种生态系统服务簇,分别为生态涵养簇、生态保护簇、粮食生产簇以及生态脆弱簇.生态脆弱簇面积占比最大,生态保护簇最小,具体顺序为：生态脆弱簇>生态涵养簇>粮食生产簇>生态保护簇;生态涵养簇提供多种生态系统服务能力最强,生态脆弱簇最弱.⑤吐哈地区全域尺度下,各生态系统服务间关系以协同为主;由于受区域土地利用类型和自然条件的影响,服务簇尺度下生态系统服务间的关系与全域尺度存在明显差异,且不同服务簇中相同服务组合的权衡/协同关系具有相似性和差异性.研究成果可为吐哈地区可持续发展和生态环境优化提供科学依据.     

Multi-scale foraging variability in Northern gannet (Morus bassanus) fuels potential foraging plasticity

The survival of marine predators depends on behavioural plasticity to cope with changes in prey distribution. Variability in behaviour might predict plasticity and is easier to assess than plasticity. Using miniaturized GPS loggers over several breeding seasons in two Norwegian Northern gannet (Morus bassanus) colonies, we investigated if and how the variability within and between individuals, but also between colonies and years, affected foraging strategies. Results revealed strong individual variability (foraging trip durations, foraging effort and different foraging areas). Individuals from both colonies showed preferred commuting routes, flight bearings and feeding hotspots. Individuals from the largest colony used larger and more foraging areas than individuals from the small colony. Feeding hotspots and foraging ranges varied amongst years in the largest colony only. Our study demonstrated that gannets show flexibility by changing prey fields that are driven by shifting oceanographic conditions.     

Observations sur le développement larvaire de Nyctiphanes couchii (Crustacea: Euphausiacea) au laboratoire

Larvae of Nyctiphanes couchii (Bell) were reared in the laboratory from the second and third calyptopis stages; they were fed animal, algal and mixed diets. Data are presented on larval morphology, growth and moulting rates. It is demonstrated that N. couchii is capable of filter-feeding and of capturing prey from the calyptopis phase onwards. The influence of diet on larval development is discussed: algal diets induce a slower growth rate than that achieved by feeding with Artemia salina nauplii alone, and increase the length of intermoult periods and of ontogenesis. A limited supply of A. salina nauplii has similar effects.