低氧、高铵和低光对沉水植物苦草(Vallisneria natans)生长与C-N代谢生理指标的影响特征

湖泊富营养化导致沉水植被大面积衰退和群落逆向演替,诱发一系列次生环境问题,并严重影响到水域生态环境质量.为了从对植物表型生长与C-N代谢生理指标影响的角度深度揭示富营养化水体中沉水植被的致衰退机制,本文以我国长江中下游淡水湖泊常见沉水植物优势种群——苦草(Vallisneria natans)为研究对象,利用L_(16)(4~5)正交试验设计方法,实验模拟研究富营养化水体中低氧、高铵和低光3种重要因素对苦草生长与C-N代谢生理指标的胁迫影响特征.本试验设置了3因素4水平,分别为4个低光照强度(50%、40%、30%和20%自然光照)和4个高铵浓度水平(0.5、1、2和4 mg/L)以及4个低氧处理浓度(7.5、6.5、5.5和4 mg/L).结果显示:光照强度低于30%、溶解氧浓度低于5.5 mg/L时,植株生长与C代谢受阻严重,碳水化合物储存量降低;铵态氮1.0 mg/L时,苦草N代谢活跃,游离氨基酸(FAA)含量明显升高,可溶性糖(SC)/FAA比降低,淀粉呈降低趋势.研究表明富营养湖泊中苦草的衰退是多种因素综合作用的结果,低氧、高铵与低光均会对苦草的生长与C-N代谢产生不利影响;受损沉水植被在藻-草稳态转换的富营养化湖泊中应通过控制水体高铵浓度,严控低氧出现,及时提高水下照度或透明度(如控磷)来予以保护和科学管理;而在次生裸地且藻类占优势的富营养化水体中沉水植被的恢复与重建过程不仅要降低水体营养盐水平尤其是氨氮的水平,还应着重考虑如何有效提高水下光强与溶解氧浓度,并将如上环境因子控制在一定变幅范围内,且控制条件应原则上严于保护受损沉水植被所需的条件.     

花生四烯酸调控网络在贻贝麻痹性贝毒代谢中的作用基于转录组和代谢组联合分析

紫贻贝（Mytilus galloprovincialis）是富集麻痹性贝类毒素（Paralytic Shellfish Toxins, PSTs）能力很强的代表性双壳贝类,但研究表明紫贻贝暴露于PSTs也会引起机体炎症反应,其作用机理及对毒素代谢影响尚不清楚。本研究采用转录组学与代谢组学联合分析技术,比较了产PSTs的链状亚历山大藻（Alexandrium catenella）暴发的不同时期,紫贻贝机体的基因表达量与代谢物含量差异,以解析PSTs胁迫下紫贻贝机体的炎症反应机制。结果表明,紫贻贝暴露于PSTs后表达的基因和代谢物均发生显著变化,其中差异表达基因17232个,差异代谢物341个。基于联合分析,差异表达基因与差异代谢物显著富集在花生四烯酸和谷胱甘肽代谢通路中,基因PLA2G2F、ALOX5、TBXAS1以及代谢物ARA、PGH₂、TXA₂、LTA₄、5-HETE对贻贝机体的促炎反应发挥重要作用;而基因GPX4、CYP2J2和代谢物15-HETE、GSH则调节机体炎症的消退。本研究揭示花生四烯酸相关通路在贻贝机体炎症反应过程中具有重要的调控作用,为下一步深度揭示PSTs胁迫下贻贝机体炎症网络化响应机制提供了研究基础。     

北京城市代谢预测研究——基于长短期记忆神经网络模型

城市化进程提升促使城市环境污染加剧、能源消耗激增、人口密度过大等问题的深层次原因在于城市代谢失调。为精准预测北京市城市代谢变化趋势,论文通过能源消费量及人类活动时间指标测算了1980—2016年北京市体外能代谢率,表征城市代谢程度。据此运用长短期记忆神经网络模型(LSTM)预测了2017—2022年北京各部门体外能代谢率。结果表明：① 基于长短期记忆神经网络的城市代谢预测模型精度较高,能够对北京各部门体外能代谢率进行更为精准的预测;② 2017—2022年间,北京第一产业和总体外能代谢率呈下降趋势,其中第一产业在2017年达到峰值,第二、第三产业及生活部门体外能代谢率将呈现增长趋势。③ 除第一、第三产业和总体外能代谢率外,历史变化的时间扰动幅度先小后大。④ 对各部门体外能代谢率EMR_T的影响贡献度最大的因子为第二产业体外能代谢率EMR₂,最小的为第一产业体外能代谢率EMR₁。论文研究结果可为政策制定者优化城市管理方案、提升城市综合实力提供理论依据和决策支持。     

鲈鱼新陈代谢过程中的碳氮稳定同位素分馏作用

利用天然存在的碳氮稳定同位素作为示踪剂，研究了在受控条件下驯养的鲈鱼的新陈代谢过程中不同生态因子(水温、摄食水平、体重等)对鲈鱼体内不同组织的碳氮稳定同位素组成的影响。通过鲈鱼新陈代谢过程中的稳定同位素分馏作用，研究了在生态系统食物网中的物质与能量转换规律。     

大弹涂鱼（Boleophthalmus pectinirostris）窒息点及昼夜代谢规律

在水温25℃时,采用封闭静水式和封闭流水式装置测定了大弹涂鱼的窒息点及其昼夜代谢规律。结果表明,大弹涂鱼的窒息点为0.71mg/L;其标准代谢（SM）和常规代谢（RM）随体质量的增加而降低,不同规格处理组昼夜变化规律相同,即夜间代谢强于白天,但不同处理组SM（F=35.247,P〈0.01）和RM（F=4.679,P〈...     

Comparison of the respiratory metabolism of juvenile Litopenaeus vannamei cultured in seawater and freshwater

Litopenaeus vannamei, a euryhaline species, can be cultured at a wide range of salinities. The emergence of freshwater pond-culture of L. vannamei is an important prelude to the continued development of shrimp culture in China. In this study, we compared the respiratory metabolism of juvenile L. vannamei cultured in freshwater and saltwater by measuring their oxygen consumption rate (OCR), ammonium-type nitrogen excretion rate (AER) and pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities at different molting stages in order to physiecologically characterize juvenile L. vannamei under freshwater conditions. The results showed that OCR was significantly higher in saltwater than in freshwater at all stages of molting cycle. However, variation of OCR among molting stages in saltwater was similar with that in freshwater, and the highest OCR was observed at post-molting stage. At all stages of molting cycle, AER was significantly higher in freshwater than in saltwater, and the highest was observed at post-molting stage. The activity of PK was significantly higher in saltwater than in freshwater. Conversely, the activity of LDH was higher in freshwater than in saltwater in general. Significant variation of PK and LDH activities in molting cycle was observed in saltwater and freshwater. The results indicated that aerobic metabolism of juvenile L. vannamei was more active in saltwater than in freshwater; while its protein metabolism was more active in freshwater than in saltwater.     

盐酸甜菜碱对短盖巨脂鲤脂肪代谢的影响

采用现场实验的方法，以短盖巨脂鲤为对象进行了60天养殖实验，探讨盐酸甜菜碱对其脂肪代谢作用机理。结果表明，盐酸甜菜碱使整鱼水分和含脂量呈下降趋势，鱼肌肉含水量下降，肝脂量极显著降低；肌肉和肝脏中游离肉碱、酸不溶肉碱含量和酸不溶肉碱与游离肉碱的比例极显著提高；血清总胆固醇和甘油三酯极显著下降，脂肪酶活性呈升高趋势；甜菜碱对肠系膜脂肪酶活力产生影响，使鱼肌肉肌问脂肪分布发生明显变化。实验结果提示：甜菜碱可改善肉质，它参与机体代谢活动，使肝脏和肌肉中甲基化产物(肉碱)含量增加，影响肠系膜脂肪酶活力，改变体脂和鱼肉脂肪酸组成，进行体脂重分配。     

Microbial Diversity in Hydrothermal Systems and Their Influence on Geological Environments

Abstract: Microorganisms found at terrestrial and seafloor hydrothermal systems are classified based on their optimum growth temperatures. Prokaryotes exhibiting optimum growth temperatures above 45C are defined as thermophiles, while those with optimum growth temperatures above 80C are called hyperthermophiles. Hyperthermophiles have chemically and thermodynamically stable cytoplasmic‐membrane consisting of ether–lipids. Hyperthermophiles observed at temperature up to 113C in seafloor hydrothermal areas should have thermostable proteins. Presumably, the thermostable proteins are replacing certain amino acid residue by proline instead of alanine in order to increase hydrogen bonds and salt bridges. Microorganisms inhabiting terrestrial and seafloor hydrothermal areas obtain energy mainly by use of chemical disequilibrium, so that their habitat may be restricted to the redox boundary between ambient water and reduced hydrothermal fluids. Among more than 200 species of cultivable thermophiles and hyperthermophiles, hyperthermophiles mainly obtain energy by sulfur reduction, because this reaction can produce energy efficiently at > 80C. Some hyperthermophilic sulfur reducers can reduce Cr(VI), Mn(IV), Fe(III), Co(III), As(V), Se(VI), Tc(VII), Au(III) and U(VI) through hydrogen or organic compounds that act as reducing agents for yielding energy. Some hyperther‐mophiles use W instead of Mo for activating their enzymes. Bacteria can pump out toxic metal ions from their cells, however toxic metal resistance systems of archaea, including hyperthermophiles, have not yet been studied. Methane producing hyperthermophiles can yield energy by the autotrophic reaction, when sufficient carbon dioxide and molecular hydrogen can be supplied and methane can be removed from hydrothermal systems. If nitrogen can be supplied into a hydrothermal system, hydrogen oxidization by nitrogen species (e.g. NO₃^‐, NO₂^‐, NO and N₂O) may be expected through the metabolism of some hyperthermophiles.     

Underwater measurements of carbon dioxide evolution in marine plant communities: A new method

We developed a new methodology to determine CO₂ fluxes in intertidal and shallow subtidal plant communities, namely seagrasses, both when the plants are submerged and when they are air-exposed. The apparatus comprises closed incubation chambers and a gas exchange column, designed to remove carbon dioxide from the water. Different types of incubation chambers were designed and built to adapt the system to distinct environments and incubation requirements. The methodology was tested under a comprehensive range of situations and its advantages and limitations are discussed. Overall, the method provides precise measurements of community carbon dioxide fluxes, through a fast and non-intrusive process, allowing repeatable in situ measurements of carbon uptake both in submerged and air-exposed conditions. As the experimental apparatus is identical, directly comparable measurements of air-exposed and submerged community production may be obtained, allowing sound estimates of daily carbon budgets of intertidal and shallow subtidal communities.     

太平洋牡蛎三倍体与二倍体特殊动力代谢的比较

采用耗氧强度测定法 ,对太平洋牡蛎三倍体和二倍体代谢进行比较研究。结果表明 ,在不同温度下 ,2n标准代谢 (StM)占常规代谢 (有饵料条件下 ,RfM)的比例平均为 85 7%( 82 6%— 91 % ) ,高于 3n的 78 4% ( 72 %— 84 3% ) ;2n因摄食所耗机械代谢变动于RfM的2 6%— 6 7% ,平均值为 4 3% ,低于 3n的 8% ( 4 9%— 1 3 6% ) ;同时 ,2n用于消化、吸收食物的代谢平均约占RfM的 9 98% ,低于 3n的均值 1 2 6%。经协方差分析检验 ,倍性对标准代谢、消化和吸收代谢及摄食代谢虽未表现出显著作用 ,但在不同生理状况下 ,2n耗氧率的均值都高于 3n。在 2 0℃下 ,对太平洋牡蛎 2n和 3n标准代谢和常规代谢 (无饵料条件下 ,RM)的昼夜周期性比较表明 ,3n的特殊动力代谢 (SDA)峰值略高于 2n,SDA持续时间和总耗能分别为 2n的 1 3倍和 0 80倍。实验还表明 ,2n和 3n在停食后 2 8h和 2 4h分别达到其排氨率的高峰 ,两者的排氨率差异虽不显著 ,但排氨率均值 3n高于 2n。