土壤理化因子与土栖节肢动物群落结构特征关系分析

在黑龙江大学呼兰校区(中国农业科学院甜菜研究所)大豆-玉米-甜菜-杂粮四区轮作制近60年的50hm2试验田中,以上年栽种玉米、大豆、甜菜、杂粮农田的土壤及相邻农田防护林带的土壤为研究对象,探讨不同生态条件下土壤理化因子与土栖节肢动物群落结构特征之间的关系。结果表明:在5种不同的农田土壤中,共收集土栖节肢动物214只,隶属于节肢动物门昆虫纲和蛛形纲。对不同土壤中动物发生数量的比较结果显示:土栖节肢动物的数量与土壤理化因子呈正相关;土栖节肢动物个体数随着土壤有机碳、全氮含量的提高而增加;土壤pH值是土栖节肢动物分布的限制因素;未经扰动的农田林带土壤中的动物数量明显高于相邻的玉米、大豆、甜菜、杂粮田。     

海南省红树林区大型底栖动物多样性的初步研究

为了解海南省红树林区的大型底栖动物群落结构及多样性现状,2009年6月对海南省7个主要红树林区进行大型底栖动物调查,采用Shannon-Wiener多样性指数(H′)、Pielous种类均匀度(J′)、 Berger-Parker优势度指数(Y)、多样性阈值(Dv)等进行种类多样性评价。结果表明,调查所采获的大型底栖动物共56种,以软体动物和甲壳类动物为主。红树林区大型底栖动物平均生物量137.67 g/m2,平均栖息密度为307.64个/m2。H′甚高,在1.94～3.41,J′在0.52～0.90,Dv达到1.01～3.07,种类多样性基本处于非常丰富和较好的水平。     

红树林区大型底栖动物研究进展

综述了近年来国内外红树林区大型底栖动物的研究进展。目前,红树林区大型底栖动物研究主要集中在物种多样性、影响因子、与其他生物的关系、次级生产力和污染生态学等方面。同时提出今后还应该更深入地进行红树林区大型底栖动物的多样性、红树林恢复过程中大型底栖动物的群落特征,并应用大型底栖动物对红树林生态系统进行监测和评价。     

贵州省务川县泥塘山封山育林区群落结构特征与土壤特性研究

为了揭示务川县泥塘山实施封山育林对天然林保护的效果,在封育4年后,对泥塘山封育区植物群落开展了调查,对区内不同地段的土壤理化性质进行了测定。结果表明,封育区内生物多样性增加,群落结构变得稳定复杂,土壤理化性质逐渐优化。在此基础上,提出了天然林培育措施。     

城市红树林系统中微塑料表面细菌群落结构特征分析

以城市红树林生态系统为研究对象,研究该系统水体中微塑料表面细菌群落结构的多样性与组分特征。采用野外原位暴露实验的方法,利用扫描电镜显微镜（SEM）和16S rDNA高通量测序技术,检测聚乙烯（PE）、聚苯乙烯（PS）、聚氯乙烯（PVC）和具有可降解性的聚乳酸（PLA）4种不同类型微塑料表面形貌特征和细菌群落结构。结果表明：4种微塑料暴露45 d后（标记为LPE、LPS、LPVC、LPLA）在其表面均能观察到明显微生物聚集体,主要以杆状细菌、球状细菌为主;不同类型微塑料表面生物膜总量存在显著差异,表现为LPE>LPLA>LPS>LPVC;4种微塑料表面的细菌群落主要包括变形菌门（Proteobacteria）和拟杆菌门（Bacteroidetes）,而水环境中以蓝细菌门（Cyanobacteria_Chloroplast）、变形菌门（Proteobacteria）、放线菌门（Actinobacteria）和拟杆菌门（Bacteroidetes）为优势菌群。基于细菌群落多样性分析,结果发现微塑料表面生物膜中的细菌群落结构和周围水体存在显著差异,各个类型的微塑料表面细菌群落结构组分相似。红树林系统是微塑料的重要收纳场所,研究微塑料表面生物膜微生物群落特征,为进一步开展城市红树林系统中微塑料的环境行为与生态风险评价提供重要参考依据。     

茶园土壤动物群落结构特征研究

采用手捡法和干、湿漏斗法,以相邻人工林地为对照,研究了茶园土壤动物群落结构特征。结果表明:茶园与人工林土壤动物群落结构存在差异,且各类群个数及其所占比例有所不同,Jaccard相似性系数为0.633,Gower系数(Sg)为0.327,土壤动物群落结构表现出较高的异质性;茶园土壤动物的类群数低于人工林,优势类群所占比例却远远高于人工林,总体群落结构较对照人工林单一;土壤动物群落的丰富度、多样性指数、密度-类群指数及分布的均匀性均低于人工林。在凋落物层以下,随着土层的加深,土壤动物类群数、个体数及多样性均呈现出一定的表聚现象,土壤动物蜱螨目/弹尾目(A/C)比值茶园(2.44)大于人工林(2.09),A/C值并未因干扰强度增大而降低,这与凋落物残留量的多少及茶园螨害有关。     

基于高通量测序技术探究套种灵芝的茶树根际土壤真菌群落结构特征

茶园套种灵芝是将茶叶加工的废弃物资源化再利用的生态循环间作模式，所形成的复合群体可以更彻底地覆盖地面，在改善土壤微生物群落结构，维持土壤微生态系统平衡等方面发挥重要作用。以未套种（CK）、套种1年（A1）、套种2年（A2）、套种3年（A3）的茶树根际土壤为研究对象，利用Miseq PE300高通量测序技术探究土壤真菌群落结构变化特征。结果表明，与CK相比，套种灵芝显著提高了茶树根际土壤碱解氮、速效磷、速效钾及有机碳含量，其中A3土壤升幅最高，各养分含量分别达32.36%、13.01%、69.21%和9.56%。α多样性指数表明，茶树根际土壤真菌群落Observedspecies指数和Chao1指数呈现CK>A3>A1>A2;ACE指数、Shannon指数和Simpson指数呈现A3>CK>A1>A2。β多样性指数表明，A2与CK、A1、A3的茶树根际土壤真菌群落组成结构差异相对较大。分类学分析发现，茶树根际土壤真菌分布于18门48纲135目309科632属。在门水平上，子囊菌门（Ascomycota）是CK、A1和A3的优势菌门，相对丰度分别为71....     

化肥减量配施有机肥下芒果园土壤细菌多样性及群落结构特征

为了探究化肥减量配施有机肥对芒果园土壤细菌多样性和群落结构的影响。本研究以海南省乐东黎族自治县某芒果园为研究对象,采用Illumina Miseq测序平台,对化肥减量配施有机肥和常规施用化肥两种施肥方式处理的芒果园土壤进行16S rRNA高通量测序分析。结果表明:通过化肥减量配施有机肥处理的芒果园土壤的有机质含量、碱解氮含量和有效磷含量比常规施肥增加了54.87%、40.73%、64.17%,镉和铅含量分别比常规施肥减少了65.09%和68.81%,而汞和铜含量分别比常规施肥增加了74.19%和32.21%。基于97.00%的相似度对所得序列进行聚类分析,2种处理的芒果园土壤中共有2702个operational taxonomic units(OTUs)。其中化肥减量处理的土壤平均有1784个OTUs,常规施肥处理的土壤平均有1568个OTUs。化肥减量配施有机肥的施肥方式能显著改善土壤质量,提高芒果园土壤细菌丰富度和多样性,并在一定程度上改变土壤细菌的群落结构。施肥方式的改变对土壤细菌的分布有较大的影响,化肥减量处理的芒果园土壤中变形菌门、放线菌门的含量较高;两种施肥方式下的土壤细菌群落结构有了明显的变化,但土壤中主要细菌的种类没有改变,土壤细菌群落结构仍保持一定的相似性;相关性分析结果显示土壤细菌群落受有机质、有效氮、有效磷和铜含量的影响较大。     

极小种群植物洛氏蝴蝶兰所处群落结构特征

洛氏蝴蝶兰（Phalaenopsis lobbii）野生资源珍贵,种群数量十分稀少,被列入我国优先拯救保护的极小种群野生植物。本研究对广西龙虎山自然保护区洛氏蝴蝶兰所在的群落1及广西大新县宝圩乡的海南风吹楠-凹脉金花茶的保护小区内所在的群落2进行了生境调查与样地调查,分析生境特征、物种组成、群落区系特点及群落结构。结果显示,调查群落1样地内共有维管束植物32科45属50种,群落生物多样性较为丰富,其中百合科为该群落的优势科;群落2样地内共有维管束植物26科35属38种,无优势科现象;所在群落属的地理成分中泛热带和热带亚洲成分占绝对优势,具有热带向亚热带过渡的性质;群落中均以高位芽植物为主,又以藤本植物的比例最大,林下郁闭度增大,表明洛氏蝴蝶兰对环境湿度和光照有一定的要求;洛氏蝴蝶兰在群落1、2草本层中重要值较低,仅作为伴生种,与常绿阔叶林群落植物共生。目前蝴蝶兰属野生植物资源的群落结构的野外调查与保育研究等方面的系统性研究较少,建议加强就地保护,结合迁地保护,研究濒危机理,通过人工栽培繁殖再进行引种回归野外,缓解洛氏蝴蝶兰野外濒危现状,并为合理开发利用提供技术支撑。     

Apoptogenic Metabolites in Fractions of the Benthic Diatom Cocconeis scutellum parva

Benthic diatoms of the genus Cocconeis contain a specific apoptogenic activity. It triggers a fast destruction of the androgenic gland in the early post-larval life of the marine shrimp Hippolyte inermis, leading to the generation of small females. Previous in vitro investigations demonstrated that crude extracts of these diatoms specifically activate a dose-dependent apoptotic process in human cancer cells (BT20 breast carcinoma) but not in human normal lymphocytes. Here, a bioassay-guided fractionation has been performed to detect the apoptogenic compound(s). Various HPLC separation systems were needed to isolate the active fractions, since the apoptogenic metabolite is highly active, present in low amounts and is masked by abundant but non-active cellular compounds. The activity is due to at least two compounds characterized by different polarities, a hydrophilic and a lipophilic fraction. We purified the lipophilic fraction, which led to the characterization of an active sub-fraction containing a highly lipophilic compound, whose molecular structure has not yet been identified, but is under investigation. The results point to the possible medical uses of the active compound. Once the molecular structure has been identified, the study and modulation of apoptotic processes in various types of cells will be possible.     

Oleosome-Associated Protein of the Oleaginous Diatom Fistulifera solaris Contains an Endoplasmic Reticulum-Targeting Signal Sequence

Microalgae tend to accumulate lipids as an energy storage material in the specific organelle, oleosomes. Current studies have demonstrated that lipids derived from microalgal oleosomes are a promising source of biofuels, while the oleosome formation mechanism has not been fully elucidated. Oleosome-associated proteins have been identified from several microalgae to elucidate the fundamental mechanisms of oleosome formation, although understanding their functions is still in infancy. Recently, we discovered a diatom-oleosome-associated-protein 1 (DOAP1) from the oleaginous diatom, Fistulifera solaris JPCC DA0580. The DOAP1 sequence implied that this protein might be transported into the endoplasmic reticulum (ER) due to the signal sequence. To ensure this, we fused the signal sequence to green fluorescence protein. The fusion protein distributed around the chloroplast as like a meshwork membrane structure, indicating the ER localization. This result suggests that DOAP1 could firstly localize at the ER, then move to the oleosomes. This study also demonstrated that the DOAP1 signal sequence allowed recombinant proteins to be specifically expressed in the ER of the oleaginous diatom. It would be a useful technique for engineering the lipid synthesis pathways existing in the ER, and finally controlling the biofuel quality.     

Effect of an Introduced Phytoene Synthase Gene Expression on Carotenoid Biosynthesis in the Marine Diatom Phaeodactylum tricornutum

Carotenoids exert beneficial effects on human health through their excellent antioxidant activity. To increase carotenoid productivity in the marine Pennales Phaeodactylum tricornutum, we genetically engineered the phytoene synthase gene (psy) to improve expression because RNA-sequencing analysis has suggested that the expression level of psy is lower than other enzyme-encoding genes that are involved in the carotenoid biosynthetic pathway. We isolated psy from P. tricornutum, and this gene was fused with the enhanced green fluorescent protein gene to detect psy expression. After transformation using the microparticle bombardment technique, we obtained several P. tricornutum transformants and confirmed psy expression in their plastids. We investigated the amounts of PSY mRNA and carotenoids, such as fucoxanthin and β-carotene, at different growth phases. The introduction of psy increased the fucoxanthin content of a transformants by approximately 1.45-fold relative to the levels in the wild-type diatom. However, some transformants failed to show a significant increase in the carotenoid content relative to that of the wild-type diatom. We also found that the amount of PSY mRNA at log phase might contribute to the increase in carotenoids in the transformants at stationary phase.     

Improvement of Neutral Lipid and Polyunsaturated Fatty Acid Biosynthesis by Overexpressing a Type 2 Diacylglycerol Acyltransferase in Marine Diatom Phaeodactylum tricornutum

Microalgae have been emerging as an important source for the production of bioactive compounds. Marine diatoms can store high amounts of lipid and grow quite quickly. However, the genetic and biochemical characteristics of fatty acid biosynthesis in diatoms remain unclear. Glycerophospholipids are integral as structural and functional components of cellular membranes, as well as precursors of various lipid mediators. In addition, diacylglycerol acyltransferase (DGAT) is a key enzyme that catalyzes the last step of triacylglyceride (TAG) biosynthesis. However, a comprehensive sequence-structure and functional analysis of DGAT in diatoms is lacking. In this study, an isoform of diacylglycerol acyltransferase type 2 of the marine diatom Phaeodactylum tricornutum was characterized. Surprisingly, DGAT2 overexpression in P. tricornutum stimulated more oil bodies, and the neutral lipid content increased by 35%. The fatty acid composition showed a significant increase in the proportion of polyunsaturated fatty acids; in particular, EPA was increased by 76.2%. Moreover, the growth rate of transgenic microalgae remained similar, thereby maintaining a high biomass. Our results suggest that increased DGAT2 expression could alter fatty acid profile in the diatom, and the results thus represent a valuable strategy for polyunsaturated fatty acid production by genetic manipulation.     

Comparison of Growth and Chemical Profile of Diatom Skeletonema grevillei in Bioreactor and Incubation-Shaking Cabinet in Two Growth Phases

Marine microalgae, diatoms, are considered a source of a wide range of high-value compounds, and numerous studies indicate their biotechnological potential in the food and feed industry, cosmetic industry, nanotechnology, pharmaceutical industry, biodiesel production, fertilizers, and wastewater treatment. The aim of this study was to compare the growth, chemical profiles, and antioxidant activity of the diatom Skeletonema grevillei cultivated in a bioreactor and an incubation-shaking cabinet at different growth phases (after 192 and 312 h). Growth was monitored by evaluating cell density with the Sedgewick Rafter chamber, and the collected biomass was extracted with 70% ethanol assisted by ultrasound. Extracts were evaporated to dryness and compounds were identified in derivatized form by gas chromatography and mass spectrometry (GC-MS) analysis, while antioxidant capacity was evaluated by DPPH and ORAC. Significantly faster growth was observed in the bioreactor than in the incubation-shaking cabinet. Oleamide, palmitelaidic acid, glycerol monostearate, myristic acid, cholesterol, eicosapentaenoic acid, 1-monopalmitin, and 24-methylene cholesterol were identified as the major compounds in both systems. Among them, oleamide was the dominant compound in both systems. It is also shown that prolonging the cultivation period had a direct effect on increasing the extract yield. The highest DPPH inhibition (11.4 ± 1%) and ORAC values (93.3 ± 8.4 mM TE) were obtained for the S. grevillei extract recovered from the bioreactor after 312 h. The obtained results contribute to the possibility of using S. grevillei for various biotechnological applications in the future.     

亚龙湾海域生态旅游及环境保护

从地理位置、水质及沉积物、红树林、珊瑚礁海岸等方面介绍亚龙湾生态自然环境特点，分析其生态旅游发展现状、形式及成效，提出对亚龙湾生态环境保护的建议。     

Haloperoxidase Mediated Quorum Quenching by Nitzschia cf pellucida: Study of the Metabolization of N-Acyl Homoserine Lactones by a Benthic Diatom

Diatoms are known to produce a variety of halogenated compounds, which were recently shown to have a role in allelopathic interactions between competing species. The production of these compounds is linked to haloperoxidase activity. This research, has shown that this system may also be involved in diatom-bacteria interactions via the H₂O₂ dependent inactivation of a type of quorum sensing (QS) molecule, i.e., N-β-ketoacylated homoserine lactones (AHLs), by a natural haloperoxidase system from the benthic diatom Nitzschia cf pellucida. The AHL degradation pathway towards corresponding halogenated derivatives was elucidated via HPLC-MS analysis and the synthesis of a broad series of novel halogenated AHL analogues as reference compounds. Furthermore, their biological activity as quorum sensing modulators was directly compared and evaluated against a series of naturally occurring β-keto-AHLs. It has been demonstrated that the loss of the QS activity results from the final cleavage of the halogenated N-acyl chain of the signal molecules.     

Electrochromic Properties and Electrochemical Behavior of Marennine,a Bioactive Blue-Green Pigment Produced by the Marine Diatom Haslea ostrearia

Marennine has long been known as the unique peculiar pigment responsible for the natural greening of oysters. It is specifically produced by the marine diatom Haslea ostrearia and it is a natural blue molecule indeed promising for food industry because of the rarity of such non-toxic, blue-colored pigments. In the search for its still not defined molecular structure, investigation of the color changes with the redox state has been carried out combining different approaches. Reducing and oxidizing chemicals have been added to purified marennine solutions and a stable blue-green color has been confirmed for the oxidized state, while a yellow color corresponded to the reduced unstable state. Raman spectroscopy has been used to monitor changes in the Raman spectra corresponding to the different colored states, and cyclic voltammetry has allowed the detection of a redox system in which protons and electrons are exchanged. These findings show that marennine is a suitable stable blue pigment for use in food applications and help in the elucidation of the chromophore structure.