Tsunami is a serious marine disaster,and accurate tsunami prediction is of great significance to marine engineering and the safety of people's lives and property.In this paper,based on 1-dimensional convolutional neural network(CONV1D),the evolution model of tsunami-like hydrodynamic characteristics of reef topography is constructed.By inputting observed values of wave heights resembling tsunami waves,the water inundation time series curves for specified locations on islands and reefs are generated.This achieves a prediction from one time series to another,serving the purpose of marine disaster prevention.The results indicate that the average relative error in predicting the arrival time of tsunami-like waves is 0.71%,and the average relative error in predicting maximum water levels is 6.99%.The hydrodynamic characteristics of island and reef terrains resembling tsunami waves obtained through CONV1D exhibit a strong alignment with numerical results.
Organic carbon burial is an important part of carbon cycle,but there are few studies on organic carbon in coral reef sediments,which affects the accurate assessment of coral reef carbon cycle.In this paper,the modern surface sediments from the outer slope of the Yongle Atoll,Xisha Islands,South China Sea,were analyzed for their total organic carbon(TOC)content,total nitrogen(TN)content,organic carbon isotope(δ13C)value,as well as sediment grain size,chlorophyll content and other indicators.The ecological condition of the outer slope of the Yongle Atoll reef is relatively good,and has the potential to represent the organic carbon characteristics in sediments of healthy coral reef ecosystems.The results showed that:1)the TOC content in the sediments from the outer slope of Yongle Atoll reef ranged from 0.71 to 1.66 mg·g-1,with an average of(1.23±0.31)mg·g-1;the TN content ranged from 0.12 to 0.28 mg·g-1,with an average of(0.20±0.05)mg·g-1.2)the C/N ratio ranged from 6.16 to 7.59,with an average of(6.75±0.34);δ13C values ranged from-17.49‰ to-15.85‰,with an average of(-16.61±0.49)‰,indicating that the organic carbon in the sediments was predominant of marine autochthonous origin and mainly from benthic plants.3)Organic carbon content was negatively correlated with water depth and positively correlated with chlorophyll a content and pheophytin content,indicating that primary productivity controlled by benthic plants was the main source of organic carbon content on the outer slope of the reef.Combined with the vertical accumulation rate of the outer reef slope sediments of the Pacific Ocean since the Holocene(2～5mm·a-1),it is inferred that the organic carbon burial flux of the outer slope of the Yongle Atoll is between 3～8g·m-2·a-1.The present study provides new information for evaluating the contribution of coral reefs in the South China Sea to the carbon cycle.
In this study,based on the field survey data of the Guangxi Shankou National Mangrove Ecological and Natural Reserve(hereinafter referred to as the Shankou Mangrove Reserve)in 2022,six time-phase remote sensing images during 1987-2021 were selected,and an object-oriented image classification method was used to analyze the status of the land-use and land-cover change(LUCC)and to calculate the landscape pattern index(LPI)based on the LUCC.This study combined LPI with LUCC to focus on exploring the wetland change process and its important influencing factors in the Guangxi Shankou Mangrove Reserve.There has been a continuous transition between land types over the past 35 years,including cultivated land continued to decrease,and Spartina alterniflora and aquaculture ponds increased,with Spartina alterniflora mainly encroaching on the former coastal mudflats,and aquaculture ponds mainly converted from forested land and cultivated land.In terms of landscape,landscape fragmentation increased,connectivity decreased,landscape shape became more complex,and landform succession became more frequent;Based on Pearson's correlation analysis,there were highly significant or significant correlations between land use change and landscape indices for coastal mudflats,mizuna mudflats,and aquaculture ponds.Significant land use changes have occurred in the Shankou Mangrove Reserve over the past 35 years,with invasive species(Spartina alterniflora)and anthropogenic disturbances(aquaculture ponds)being the main factors influencing changes in mangrove wetlands in the area,and the main contributors to the continued increase in landscape fragmentation.This study reveals the influencing factors of regional landscape changes,which can provide a theoretical basis for the environmental management and protection of typical mangrove ecosystems.
为获得具有较好抑制植物病原菌活性的化合物,对一株海洋链霉菌Streptomyces sporoverrucosus 33510的化学成分及活性进行了研究。使用高效液相色谱（high performance liquid chromatography, HPLC）、半制备液相色谱（semi-pre HPLC）、柱色谱（colume chromatography, CC）、薄层色谱（thin layer chromatography, TLC）和重结晶等分析及分离技术对该菌株的发酵产物进行了分离纯化。采用核磁共振（nuclear megnetic resonance,NMR）、质谱（mass spectra,MS）、旋光（optical rotatory dispersion,ORD）等波谱学方法对得到的化合物进行结构鉴定。通过滤纸片法对化合物进行抑菌活性检测。从33510菌株的发酵产物中共分离得到10个化合物,分别为:cyclo（D-Pro-D-Leu）（1）、bisphenol A （2）、methylp-hydroxyphenylacetate （3）、N-phenethylacetamide（4）、3-indole-methylethanoate（5）、dibutyl phthalate（6）、cyclo（D-Pro-L-Leu）（7）、cyclo（D-Pro-L-Ile）（8）、cyclo（L-Pro-L-Phe）（9）和cyclo（L-Leu-L-Val）（10）。除化合物5和9外,其他8个化合物均为首次从该菌种中分离得到。抑菌结果表明,抑菌摩尔浓度为0.19mmol·L -1 时,化合物2对板栗疫病菌（Cryphonectria parasitica）的抑制效果为高敏（抑菌直径为20mm）。
Quantifying eddy mixing in the ocean is a hot and tough problem in the area of physical oceanography.Based on the theory of effective diffusivity,the present study investigated the stirring effects of geostrophic turbulence that led to stretching,distorting,deforming,and folding of tracer contours.These changes are then related to the efficiency of turbulent mixing.Results show that under the stirring effect of geostrophic turbulence,the length of tracer contour can be quickly elongated and fine-scale tracer filaments and fronts are also generated.This fractal elongation of tracer contour,about 10～20 times longer than the original length,is the dominant contributor to the mixing efficiency,whereas the gradient enhancement associated with filament and front generations only plays a secondary role.On the other hand,fine-scale features are smoothed out by small-scale diffusivity which eventually suppresses the increase of contour length and the generation of tracer filaments.This imposes an upper bound of the mixing efficiency when the stirring and smoothing effects are in a dynamical balance.Through a'box-counting'method,the fractal dimension of tracer contour is also found between 1.4～1.6,indicating a geometric dimension lies somewhere between 1D and 2D.Due to the limitation of data resolution,contour length and thus mixing efficiency may be underestimated.Finally,the present study made an empirical relation between the fractal dimension and mixing efficiency,providing an opportunity for estimating mixing efficiency through a well-developed pattern recognition technique in remote sensing,and a new way of diagnosing ocean mixing and its parameterization.
The South China Sea is the core interest of China.Since the 1950s,dozens of large-scale comprehensive marine scientific surveys in the South China Sea and its affiliated islands have been organized.A large number of important raw data were obtained.However,early data has not yet been digitized,with varying standards for data recording,quality control,and archiving,and is even scattered or on the verge of loss of original materials.There is an urgent need for rescue and reorganization.The"Reorganization of historical data from scientific investigations of the South China Sea and its affiliated islands and reefs"has completed the standardized compilation of historical data from 353 projects,664 voyages,and over 200 elements from 1950 to 2019.It has constructed a comprehensive database of first-hand surveyed and valuable scientific data,including hydrometeorology,marine chemistry,bioecology,fishery resources,geological environment,and geological samples of islands and reefs.At the same time,scientific analysis of the data was completed,and some new analytical data products were formed.A set of 12 books titled"Compilation of Historical Materials for the South China Sea Scientific Expedition"and 7 other monographs were published.This series of articles is divided into three parts.Article 1 focuses on the systematic compilation of historical data,and briefly discusses the implementation steps of standardized compilation,and proposes the corresponding strategies for technical difficulties;Article 2 briefly discusses the research and practice of the South China Sea ocean data governance technology for scientific management of integrated data;Article 3 briefly discusses the construction practice and innovative application of"Digital South China Sea"for the sharing service of integrated data.This series of articles comprehensively discusses the research process and practical experience of the comprehensive database and"Digital South China Sea",providing reference for the data standardized compilation of the relevant marine scientific investigations.
To explore the histological and ultrastructural changes of the annual development of the testis and spermatogenesis of Lutraria sieboldii in Beibu Gulf of Guangxi,the annual development of testis and ultrastructure of spermatozoa of L.sieboldii were studied through tissue section,scanning and transmission electron microscopy.Results showed that the testis completes a cycle in one year,which can be divided into proliferating stage,growing stage,maturing stage,spawning stage and resting stage.The spawning was from December to April of the following year,and the testis development of 5%～10%individuals in each stage was slightly delayed.Spermatogenesis can be divided into proliferation period,growth period,mature period and metamorphosis period.The male reproductive cell can be divided into Spermatogonia stage,primary spermatocyte stage,secondary spermatocyte stage,spermatocyte stage and mature sperm stage.The sperm of L.sieboldii belongs to the flagella type,whose total length is(39.76±0.50)μm.The sperm head was composed of a nearly subelliptic spermatic acrosome and nucleus,the bottom of the acrosome and the spermatozoa connected with the spermatozoa were depressed to form a subacrosomal cavity.The electron density in the nucleus was uniform,and there was a gap in the middle of the nucleus.There are four mitochondria around the centriole complex to form the middle part of sperm,and the mitochondria are nearly round with apparent internal ridge.The plasma membrane wraps around the axial filaments to form sperm tail,and the"9 + 2"doublet microtubule structure can be clearly observed in the transverse section of the tail.In addition,there are two different types of spermatogonia:type A spermatogonia has no nucleolus in the nucleus while type B spermatogonia has nucleolus in the nucleus,and type B spermatogonia is distributed in the testis at different stages.
In this study,ovarian development,reproductive cycle,egg development and its ultrastructure of Paphia textile in Beibu Gulf of Guangxi were investigated using anatomical observation,ovarian tissue sectioning and transmission electron microscopy techniques.The results showed that P.textile has one reproductive cycle in one year,and the ovarian development of P.textile can be divided into five stages:proliferating stage(May to July),growing stage(July to September),maturing stage(September to November),spawning stage(November to January of the next year),and resting stage(January to April of the next year).According to the relevant characteristics of the egg development and vitellogenesis of P.textile,it can be divided into four main stages:the first stage is the oocytes stage,the second stage is the phase of previtellogenesis oocytes stage,the third stage is the phase of vitellogenesis oocytes stage,and the fourth stage is the phase of postvitellogenic oocytes stages.The phase of vitellogenesis is an important stage of vitellogenesis,during which mitochondria,endoplasmic reticulum,golgiosome,lysosomes and other organelles form yolk granule in different ways.The water temperature in the sea area was closely related to the ovarian development of P.textile and was an important factor affecting the ovarian development of P.textile.P.textile is hermaphroditic,and no hermaphroditism has been found.The results of the study provide providing basic data for reproductive biology,artificial breeding,breeding and germplasm resources protection of P.textile.
Yongle Atoll was the largest atoll in the Xisha Islands of the South China Sea, and it was a coral reef ecosystem with important ecological and economic values. In order to better protect and manage the coral reef fish resources in Yongle Atoll, we analyzed field survey data from artisanal fishery, catches, and underwater video from 2020 to 2022 and combined historical research to explore the changes in fish species composition and community structure in Yongle Atoll over the past 50 years. The results showed that a total of 336 species of fish were found on Yongle Atoll, belonging to 17 orders and 60 families. Among them, Perciformes had the most fish species with 259 species accounting for 77.08% of the total number of species. The number of fish species in the coral reef of Yongle Atoll was exponentially correlated with its corresponding maximum length and significantly decreases with its increase. The fish community structure of Yongle Atoll changed, and the proportion of large carnivorous fish decreased significantly, while the proportion of small-sized and medium-sized fish increased. At the same time, Yongle Atoll has 18 species of fish listed on the IUCN Red List, 15 of which are large fish. The average taxonomic distinctness (Delta+, Δ+) and the variation taxonomic distinctness (Lambda+, Λ+) in 2020–2022 were lower than the historical data, and the number of fish orders, families, and genera in Yongle Atoll has decreased significantly, which indicates that the current coral reef fish species in Yongle Atoll have closer relatives and higher fish species uniformity. In addition, the similarity of fish species in Yongle Atoll was relatively low at various time periods, further proving that the fish community structure has undergone significant variation. In general, due to multiple impacts, such as overfishing, fishing methods, environmental changes, and habitat degradation, the fish species composition of Yongle Atoll may have basically evolved from carnivorous to herbivorous, from large fish to small fish, and from complexity to simplicity, leaving Yongle Atoll in an unstable state. Therefore, we need to strengthen the continuous monitoring of the coral reef ecosystem in Yongle Atoll to achieve the protection and restoration of its ecological environment and fishery resources, as well as sustainable utilization and management.
钙化海藻作为一类重要的钙化生物,不仅能构建稳固礁体,而且部分藻株能诱导珊瑚幼虫附着变态,在珊瑚礁生态系统中具有极其重要的生态功能.但是,面对未来海水酸化与升温的共同作用,珊瑚藻生理过程会发生怎样的变化,目前尚不清楚.本文选取了广泛分布于珊瑚礁生态系统中的一种钙化海藻——孔石藻(Porolithon cf.onkodes)为研究对象,采用3个CO2分压(pCO2:400μatm、1200μatm、1800μatm)和温度(27℃、30℃、32℃)对其培养1个月,通过监测藻体生长和钙化等参数的变化情况,探究海水酸化与升温对活体与死亡的孔石藻的影响.研究结果表明,当温度从27℃升高到30℃时,活体孔石藻生长钙化没有受到显著影响;但当温度提高到32℃时,藻体生长钙化显著下降,甚至出现溶解现象,净钙化速率从206.99nmol·cm–2·h?1(pCO2:400μatm;温度:27℃)降至–42.22nmol·cm–2·h?1(pCO2:1200μatm;温度32℃).类似地,pCO2增加也会显著抑制活体孔石藻的生长钙化,而且该抑制作用随着CO2分压增加而增强.此外,升温与酸化对藻体叶绿素a含量和净钙化速率均具有交互作用.与活体孔石藻相比,死亡的藻体骨骼更易受到高温与酸化影响,当温度升高至30℃或pCO2提高至1200μatm时,死亡藻体骨骼净溶解速率均显著增加,而且高温与酸化的交互作用加速了骨骼溶解速率.研究结果表明了酸化与升温不仅会影响活体孔石藻的生长钙化速率,而且会加速礁体主要组分(藻体碳酸钙骨骼)的溶解速率,进而影响到珊瑚礁生态系统.本文研究结果对预测未来气候变化对珊瑚礁生态系统的影响、制定珊瑚礁生态系统保护与修复策略均具有重要的理论价值和生态意义.
太平洋板块沿希库兰吉海沟俯冲至新西兰北岛下方300km左右,向南与新西兰南岛发生碰撞,导致北岛发生顺时针旋转.该区域为研究俯冲带地幔楔变形,理解俯冲过程中地幔物质运动及其动力学过程的理想场所.本研究利用近震(深度范围在70～150km)S波分裂计算获得了北岛弧后塔拉纳基地区的地幔楔各向异性特征,结果显示快波方向和延迟时间在空间上存在一定的变化.深度在120km之上的地震对应的快波优势方向为NE—SW,近似平行于海沟走向,反映了地幔楔中平行于海沟方向的地幔流动引起的橄榄岩晶格优势排列;而120km之下地震主要集中在塔拉纳基地区北部,快波方向为NNE—SSW向,且延迟时间随深度增大而增加.由于太平洋板块俯冲到100～150km处的俯冲角度急剧变陡至近似直立,引起深部地幔楔强烈变形.因此,推测弧后北部深度>120km地震的NNE—SSW快波方向可能是受到地幔楔中平行于海沟走向的地幔流动,以及俯冲角度变陡而使深部地幔楔强烈变形的共同作用的结果.弧后北部地幔楔深部的拉张作用更为强烈,是造成各向异性在空间上变化的主要原因.
文章对分离自南海深海沉积物的 1 株真菌 101#进行分子鉴定、次生代谢产物及其生物活性研究.基于 rDNA-ITS基因序列分析法对菌株进行鉴定,运用高效液相色谱(high performance liquid chromatography,HPLC)跟踪其发酵产物含量的变化,采用硅胶柱层析、Sephadex LH-20 层析、HPLC等多种方法进行代谢产物分离纯化;利用核磁共振、质谱等波谱学方法并结合参考文献报道对分离的单体化合物进行结构鉴定.采用滤纸片扩散法和卤虫致死法分别测定抗菌和卤虫致死性活性.结果表明,该菌株鉴定为黄曲霉(Aspergillus flavus),第 28天的发酵产物含量最丰富.此外,该粗提物对 15种指示菌均具有一定的抑制活性,其中对 10 种革兰氏阳性菌和阴性菌的最小抑菌浓度(minimum inhibitory concentration,MIC)范围为0.781～6.25μg·mL-1,对 3种植物病原菌MIC范围为 50～200μg·mL-1,对海洋生物污损菌(麦氏交替单胞菌)和致病真菌(多耐白色念珠菌)MIC值分别为 3.125μg·mL-1和 1.563μg·mL-1,对卤虫 1、12、24和 48 h的半数致死浓度(Median Lethal Dose 50,LD50)分别为 74.597、24.322、13.797和 8.559mg·mL-1.最后,从乙酸乙酯萃取部位中共得到 4个单体化合物,分别鉴定为 5-chloro-2-hydroxyphenylacetic acid(1)、aspergamide A(2)、WF-3681 methyl Ester(3)和(E)-But-2-enedioic acid monomethyl Ester(4),这 4 个化合物对枯草芽孢杆菌、多耐白色念珠菌、苏云金芽孢杆菌、希瓦氏菌和藤黄微球菌显示出一定的抑制活性,其 MIC值范围为 6.25～200μg·mL-1,此外,化合物 1～4 均显示出较强的卤虫致死活性,其 LD50 值分别为 7.40、11.95、17.69和 23.35μg·mL-1.
针对热带气旋灾害的复杂性和不确定性,文章基于贝叶斯网络和地理信息系统(geographic information system,GIS)提出了一种新的热带气旋灾害风险评估模型.该模型能够从客观历史数据中自动挖掘灾害影响因素间的因果关系,并以概率形式进行表达和推理,从而对不确定灾害风险进行评估预测.基于 1980-2016 年中国东南沿海三省(广东、福建、浙江)的热带气旋灾害历史数据进行风险评估实验,选取致灾因子危险性、孕灾环境敏感性、承灾体脆弱性 3 个方面共计 12 个评估指标作为模型输入,直接经济损失量化为灾害风险等级作为模型输出,构建基于贝叶斯网络的风险评估模型.然后利用 2017-2021 年热带气旋灾害数据进行模型检验,评估预测的准确率为 80.75%.模型预测的极低、低、中、高和极高风险的相对误差分别为 27.72%、8.45%、18.58%、16.52%和 19.12%,风险预测值的区划结果在空间形态上与实际灾害损失分布高度一致.此外,还将评估模型构建方法应用于"莫兰蒂"台风灾害个例的风险评估.结果表明,模型评估出的灾害高风险和极高风险区域与实际灾情报告基本一致.由此可见,本研究建立的热带气旋灾害风险评估模型具有较高的准确率和可信度,为热带气旋灾害风险评估提供了一种新的方法途径和技术支撑.
滤食性浮游被囊动物在开阔大洋和沿海海域中大量存在,通过黏液网来大量过滤海水浓缩食物颗粒以供种群快速增殖,是生物碳泵的关键组成,对海洋生物地球化学循环和生态系统能量流动均有重要意义.文章从浮游被囊动物生物学特征、植食性滤食作用、生活史特异性等方面综合论述了国内外关于浮游被囊动物在摄食海洋微型生物、调节海洋生物碳泵(biological carbon pump,BCP)和改变微型生物群落结构以及联系深海食物网等方面的作用.概括了国内外影响浮游被囊类暴发的食物因素、生活史特征、海洋动力过程及气候变化等相关研究进展.浮游被囊动物通过黏液过滤打包真光层微型生物,产生的粪便球和胶质死体快速沉降而输出成为胶质碳泵,从而增加BCP效率,改变微型生物碳循环途径;作为上层海洋生态系统与深海生态系统的媒介,胶质坠落在深海群落和底栖动物食物网中扮演重要作用.文章最后总结了其他胶质碳泵的相关研究进展,并提出在全球变化背景下,未来的研究应该更多地着眼于动力过程对不同生活史阶段浮游被囊动物的垂直移动和集群的影响,并将过滤摄食对微生物群落影响及繁殖策略响应与海洋物理、化学和生物环境多维度联系起来,全面解释浮游被囊类暴发的内在和外在机制,有助于准确评估海洋被囊类胶质碳泵效率及其对全球变化的响应.
文章模拟微生物自然生长环境,对两株海洋本草软珊瑚曲霉属真菌Aspergillus sp.EGF7-0-1和Aspergillus sp.EGF15-0-3 进行共培养,以期发现新颖骨架成分.采用硅胶、反相色谱、羟丙基葡聚糖凝胶和高效液相色谱等方法对其次生代谢产物进行分离、纯化;采用高分辨质谱、核磁共振、旋光及物理常数对照等方法对所分离得到的化合物进行结构鉴定;采用全球天然产物分子网络(Global Natural Products Social Molecular Networking,GNPS)方法对次生代谢产物进行分析.从两株软珊瑚来源的曲霉属真菌大米共培养中分离得到 10 个甾体类化合物:Chaxine(1)、Herbarulide(2)、dankasterones A(3)、25-hydroxyergosta-4,6,8(14),22-tetraen3-one(4)、Ganodermasides D(5)、Ergosta-4,6,8(14),22-tetraen-3-one(6)、Ergosta-4,7,22-trien-3-one(7)、Isocyathisterol(8)、Stigmasta-4,22-dien-3-one(9)和β-sitostenone(10).化合物 1～3均为高度氧化重排的甾体类化合物.化合物 4、5、7和 9首次从曲霉属真菌中分离得到.GNPS分析表明与菌株EGF7-0-1和EGF15-0-3单培养相比,两株真菌共培养能诱导出更为丰富的甾体类化合物.
滨海酸性硫酸盐土成土母质中富含还原性硫化物(reducing inorganic sulfur,RIS)和活性铁等生源要素,耦合制约着铁、硫以及重金属元素的环境地球化学行为.为了揭示滨海酸性硫酸盐土壤湿地沉积物中 RIS和活性铁的耦合机制及环境意义,文章通过在钦江河口滨海酸性硫酸盐土壤湿地采集深约 40cm的沉积柱状样,在垂向上对酸性可挥发硫(acid volatile sulfide,AVS)、黄铁矿硫(chromium reducible sulfur,CRS)、元素硫(elemental sulfur,ES)和活性铁[(Fe(Ⅱ)和 Fe(Ⅲ)]的含量和分布规律进行了厘定,并结合沉积物的理化性质进行探讨分析.结果表明:钦江河口酸性硫酸土中的活性铁中以Fe(Ⅲ)为主,活性铁中的Fe(Ⅱ)和Fe(Ⅲ)在环境容易发生相互转换,氧化还原电位(Eh)越低、有机质(organic matter,OM)含量越高越利于Fe(Ⅲ)还原为Fe(Ⅱ);还原性无机硫以CRS为主,其次为AVS以及少量ES,成岩过程中还原性无机硫会相互转化,其过程主要受到活性铁和 OM 控制,但研究区还原性无机硫形成的限制因素并非活性铁,而是 OM 的含量及活性;较高的 OM 和 Fe(Ⅱ)易造成AVS富集,较高的Fe(Ⅲ)和Eh值利于ES生成,CRS除受OM和活性铁的控制,还受到AVS转化率的影响;研究区大部分样点的CRS/AVS比值较低,表明AVS不能有效的转化为CRS,硫化物活性与生物有效性较高.因此应尽量避免外源OM引入和人为活动扰动,以免造成还原性无机硫氧化释放出H+形成酸害,同时降低吸附或共沉淀在还原性无机硫上的重金属等污染物的浸出,以减少环境破坏.
文章以假微型海链藻(Thalassiosira pseudonana)转录组测序数据为基础,对差异表达的功能基因进行 GO(gene ontology)和KEGG(kyoto encyclopedia of genes and genomes)富集分析,以研究低盐胁迫条件对其脂肪酸代谢通路相关功能基因表达的影响.结果发现,不同盐度培养下的假微型海链藻在生长期的第 2天与第 4天时细胞中与脂肪酸生物合成、脂肪酸延伸的相关基因(如:ACC1、arm)的表达量相对于生长第 1天均显著升高,与脂肪酸降解相关基因(如:ACADM、ECI1)的表达量无显著变化;与脂肪酸的生物合成、延长相关基因的表达量在试验组和对照组间存在差异(如:起重要作用的 KASⅠ、ACAA2等基因表达量显著增加,但也有少数处于下降或者微变动的状态),与脂肪酸降解过程相关基因的表达量显著上升.
微生物的碳水化合物活性酶(carbohydrate active enzymes,CAZymes)是海洋沉积物有机碳降解过程中的关键.文章基于大亚湾 2020年春季表层沉积物的宏基因组数据,分析鉴定编码CAZymes序列种类及其在微生物中的分布,并预测了微生物群落对不同结构聚糖的利用.结果表明,表层沉积物微生物群落对不同结构聚糖的利用能力不同.δ-变形菌纲是编码降解肽聚糖和几丁质相关酶类序列的最大贡献者;γ-变形菌纲、拟杆菌门和浮霉菌门具有最高的 CAZymes家族的 α-生态多样性(香浓指数),是编码降解结构复杂多糖(岩藻聚糖、昆布多糖、纤维素等)的 CAZymes基因优势种群;酸杆菌是编码裂解寡聚半乳糖醛酸多糖酶序列的优势菌群.古菌对大部分 CAZymes 贡献低于 1%,但对编码降解纤维素和半纤维素的碳水化合物酯酶(carbohydrate esterase,CE)序列、结合模块(carbohydrate binding module,CBM)基因序列贡献较突出(贡献介于 2.18%～11.1%).CAZymes的底物主要源自于湾内自生的有机碎屑,降解藻源有机碎屑的CAZymes序列的相对丰度于湾口高于湾东北部.与木质素降解相关的辅助活性家族(auxiliary activity families,AAs)序列相对丰度在湾东北部最高,主导的AAs可能有助于增加木质纤维素的溶解度,进而提高糖苷酶对木质纤维素的生物利用度.大亚湾表层沉积物中微生物及其 CAZymes序列组成主要与上层水体有机颗粒沉降以及水深相关.
氧化还原敏感元素(Mo、U、V、Re、Ni、Co、Cr)已被广泛用于判别沉积环境的氧化还原状态,以及计算上覆水体和大气层中的氧气浓度.然而海底冷泉活动由于微生物作用形成的硫化氢可以导致这些元素指示的氧化还原信号发生变化和模糊,进而影响氧化还原状态判别的有效性.文章通过对南海活动冷泉 F 站位海底 3 根插管沉积物的氧化还原敏感元素地球化学特征分析,发现冷泉活动区海底沉积物相比正常海底环境普遍表现为较高的Mo含量,并指示孔隙水为硫化环境,表明甲烷厌氧氧化作用形成的硫化氢对沉积物中Mo富集具有促进作用.冷泉沉积物的U/Th、V/Cr和Ni/Co显示底层海水具有较高的氧浓度,与正常海底特征相一致.但是V/(V+Ni)>0.7指示了沉积物形成时的环境缺氧,可能与陆源碎屑中较低的Ni含量有关.冷泉沉积物Re/Mo比值接近现代海水值,与现代海洋硫化盆地的特征类似,指示了冷泉附近海洋硫化分层特征.因此冷泉活动区海底沉积物的Re和Mo容易受到甲烷渗漏的影响,不能可靠指示真实的氧化还原状态.
为寻找海洋来源结构新颖的次生代谢产物,采用大米培养基对海洋本草软珊瑚(Sinularia sp.)共附生真菌Aspergillus sp.EGF7-0-1进行规模发酵,利用高效液相色谱等多种柱色谱技术对其乙酸乙酯提取物进行分离纯化;采用核磁共振波谱、高分辨质谱、旋光光谱等现代光谱学方法,并结合文献数据比对等对其进行结构鉴定,获得 10个简单芳香酚酸化合物,分别为 4-hydroxy-3-(3'-methyl-2'-butenyl)phenylacetic acid(1)、asperulosin C(2)、对羟基苯乙酸(3)、对羟基苯乙酸甲酯(4)、4-hydroxy-3-prenyl-benzoic acid(5)、4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde(6)、对羟基苯甲醛(7)、对羟基苯甲酸甲酯(8)、间羟基苯乙酸(9)和 2,2'-oxybis(1,4)-ditert-butylbenzene(10),其中化合物 1 是新发现的天然产物.抗肿瘤活性研究表明,化合物 1～10 对人结肠癌细胞、人乳腺癌细胞、人肝癌细胞、小鼠肝癌细胞、小鼠乳腺癌细胞、小鼠黑色素瘤细胞和小鼠皮肤黑色素瘤细胞等肿瘤细胞均无活性.
