diatoms

硅藻
  • 文章类型: Journal Article
    由于人为气候变化,海水温度正在升高,对海洋生态系统构成重大威胁。硅藻是主要的海洋初级生产者,因此,它们受到海洋热浪和海洋温度上升的影响。此外,在低潮下,硅藻经常暴露在高温下。然而,对长期暴露于热应激的生理和表观遗传反应在硅藻毛指藻中仍然未知。在这项研究中,我们调查了细胞形态的变化,光合作用,和H3K27me3丰度(表观遗传标记,由组蛋白H3上赖氨酸27的三甲基化组成)。PtEZH受损的突变体-沉积H3K27me3的酶-表现出减少的生长和PSII量子能力的适度变化。我们观察到了三种形态型的形态变化。tricornutum(梭形,椭圆形,和三辐射)以响应热应力。发现这些变化在PtEZH的控制下。此外,中等和升高的热应力都调节了编码与光合作用有关的蛋白质的基因的表达。最后,热应激导致各种形态类型的全基因组H3K27me3水平降低。因此,我们提供了H3K27me3标记的表观遗传控制的直接证据,表明了三角皮指藻对热应激的反应。
    Marine water temperatures are increasing due to anthropogenic climate change, constituting a major threat to marine ecosystems. Diatoms are major marine primary producers, and as such, they are subjected to marine heat waves and rising ocean temperatures. Additionally, under low tide, diatoms are regularly exposed to high temperatures. However, physiological and epigenetic responses to long-term exposure to heat stress remain largely unknown in the diatom Phaeodactylum tricornutum. In this study, we investigated changes in cell morphology, photosynthesis, and H3K27me3 abundance (an epigenetic mark consisting of the tri-methylation of lysine 27 on histone H3) after moderate and elevated heat stresses. Mutants impaired in PtEZH-the enzyme depositing H3K27me3-presented reduced growth and moderate changes in their PSII quantum capacities. We observed shape changes for the three morphotypes of P. tricornutum (fusiform, oval, and triradiate) in response to heat stress. These changes were found to be under the control of PtEZH. Additionally, both moderate and elevated heat stresses modulated the expression of genes encoding proteins involved in photosynthesis. Finally, heat stress elicited a reduction of genome-wide H3K27me3 levels in the various morphotypes. Hence, we provided direct evidence of epigenetic control of the H3K27me3 mark in the responses of Phaeodactylum tricornutum to heat stress.
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  • 文章类型: Journal Article
    外写组学被认为是真核生物发育过程和应激反应的新调控步骤。这项研究的目的是,第一次,在四个研究物种中鉴定RNA甲基转移酶(作者)和去甲基酶(橡皮擦),即,鞭毛藻Alexandriumtamutum和Amphidiniumcarterae,硅藻,和绿色的海藻四叶鱼。作为感兴趣的酶类的查询序列,我们选择了以前在海洋植物中检测到的那些,评估它们在营养饥饿应激暴露时的表达。假设是在压力暴露后,可能会发生特定写入器和橡皮擦的激活/停用。在微藻中,我们发现几乎所有的植物作家和橡皮擦(ALKBH9B,ALKBH10B,MTB,和FIP37),除了三位作家(MTA,VIRILIZER,和HAKAI)。通过扫描相应基因组的序列相似性搜索确认了它们的存在。因此,我们得出的结论是,所研究的转录组缺乏这三个作者序列,可能是因为它们在那些实验条件下没有表达,而不是真正缺乏基因组中的这些基因。这项研究表明,其中一些仅在特定的培养条件下表达。我们还研究了它们在其他培养条件下的表达(即,氮耗尽,磷酸盐消耗,和两种不同浓度的锌添加)在A.carterae中,对它们在应激时调节基因表达的可能作用提供了新的见解。
    Epitranscriptomics is considered as a new regulatory step in eukaryotes for developmental processes and stress responses. The aim of this study was, for the first time, to identify RNA methyltransferase (writers) and demethylase (erasers) in four investigated species, i.e., the dinoflagellates Alexandrium tamutum and Amphidinium carterae, the diatom Cylindrotheca closterium, and the green alga Tetraselmis suecica. As query sequences for the enzymatic classes of interest, we selected those ones that were previously detected in marine plants, evaluating their expression upon nutrient starvation stress exposure. The hypothesis was that upon stress exposure, the activation/deactivation of specific writers and erasers may occur. In microalgae, we found almost all plant writers and erasers (ALKBH9B, ALKBH10B, MTB, and FIP37), except for three writers (MTA, VIRILIZER, and HAKAI). A sequence similarity search by scanning the corresponding genomes confirmed their presence. Thus, we concluded that the three writer sequences were lacking from the studied transcriptomes probably because they were not expressed in those experimental conditions, rather than a real lack of these genes from their genomes. This study showed that some of them were expressed only in specific culturing conditions. We also investigated their expression in other culturing conditions (i.e., nitrogen depletion, phosphate depletion, and Zinc addition at two different concentrations) in A. carterae, giving new insights into their possible roles in regulating gene expression upon stress.
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  • 文章类型: Journal Article
    北斗星(Cincluscinclus)是与河岸生态系统密切相关的物种,已知以水生大型无脊椎动物为食,对水污染敏感。为此,已提出将滴水用作水质的有用生物指标。虽然北斗星的分布和生态在北欧河流中众所周知,在意大利中部,很少有研究关注这个问题,缺乏北斗星保护的数据。这里,我们的目标是(i)使用基于硅藻和大型无脊椎动物群落的生物指数评估与水质相关的北斗星发生,(ii)评估河流生态系统的整体状态,通过缓冲区的河流功能指数和土地利用分析。总的来说,仅靠水质并不能解释北斗星的发生,因为在许多具有良好或高水质的潜在合适地点都没有发现该物种。此外,硅藻和大型无脊椎动物群落的多样性也不是足够的限制。相反,北斗星的发生与河流功能指数显著相关,整合了几个河岸生态系统因素,这表明具有高功能水平的保存完好的生态系统对于北斗星的发生很重要。现场周围地区的土地利用分析显示,虽然不重要,相当自然的水平,可能有利于河岸区的维护。由于北斗星在意大利中部被认为正在下降并受到威胁,迫切需要进一步研究其自动生态和保护威胁。最后,考虑到物种和河岸生态系统之间的联系,像北斗星这样有魅力的物种可以用作保护和保护项目中的伞形物种,以造福整个河岸带,它代表了陆地和水生生态系统之间至关重要的缓冲区,尽管经常导致严重减少和分散。
    The dipper (Cinclus cinclus) is a species strongly linked to the riparian ecosystem, known to feed on aquatic macroinvertebrates, which are sensitive to water pollution. For this, dippers have been proposed as useful bioindicators of water quality. While the distribution and ecology of the dipper are well known in Northern European rivers, few studies focus on this in Central Italy, lacking data for dipper conservation. Here, we aimed to (i) assess the dipper occurrence related to water quality using biotic indices based on diatom and macroinvertebrate communities, and (ii) evaluate the river ecosystem\'s overall state, through the River Functionality Index and land-use analysis in buffer areas. Overall, water quality alone does not explain the dipper occurrence, as the species was not found in many potentially suitable sites with good or high-water quality. Moreover, the diversity of the diatom and macroinvertebrate communities was not a sufficient constraint either. Conversely, the dipper occurrence significantly correlated with the River Functionality Index, which integrates several riparian ecosystem factors, indicating that well-preserved ecosystems with high functionality levels are important for dipper occurrence. Land use analyses in the areas surrounding the presence sites have shown, although not significantly, a fair level of naturalness, potentially favouring the riparian zone maintenance. As the dipper was considered in decline and threatened in Central Italy, further research on its auto-ecology and conservation threats is urgently needed. Finally, given the link between the species and the riparian ecosystem, a charismatic species such as the dipper could be used as an umbrella species in protection and conservation projects for the benefit of the entire riparian belt, which represents a buffer area of fundamental importance between terrestrial and aquatic ecosystems, although often resulted severely reduced and fragmented.
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  • 文章类型: Journal Article
    浮游植物和异养细菌之间的相互作用显著影响海洋中有机碳的循环,许多这些相互作用发生在微米级。我们探索了两种大小的特定浮游植物和细菌之间的潜在关联,0.8-3µm且大于3µm,在南大洋的三个自然铁施肥站和一个高营养低叶绿素站。通过对DNA和RNA提取物的rbcL基因和16SrRNA基因进行测序,确定浮游植物和细菌群落的组成,代表存在和潜在活动,分别。硅藻,尤其是thalassiosira,对较大尺寸部分的DNA序列有显著贡献,而在较小尺寸的部分中,单藻细胞占优势。最丰富的浮游植物和细菌操作分类单位之间的相关性分析显示,黄囊藻和皮真核生物与SAR11,SAR116,磁螺旋体,和Planktomarina.相比之下,大多数Thalassiosira操作分类单位与杆菌属的相关性最高,硫杆菌,红细菌,和狮身人面像,而Fragilariopsis,Haslea,与OM60,Fluviicola,和Ulvibacter.我们的现场观察表明浮游植物和细菌类群之间存在明显的联系,这可能在南大洋的养分循环中起着至关重要的作用。
    Interactions between phytoplankton and heterotrophic bacteria significantly influence the cycling of organic carbon in the ocean, with many of these interactions occurring at the micrometer scale. We explored potential associations between specific phytoplankton and bacteria in two size fractions, 0.8-3 µm and larger than 3 µm, at three naturally iron-fertilized stations and one high nutrient low chlorophyll station in the Southern Ocean. The composition of phytoplankton and bacterial communities was determined by sequencing the rbcL gene and 16S rRNA gene from DNA and RNA extracts, which represent presence and potential activity, respectively. Diatoms, particularly Thalassiosira, contributed significantly to the DNA sequences in the larger size fractions, while haptophytes were dominant in the smaller size fraction. Correlation analysis between the most abundant phytoplankton and bacterial operational taxonomic units revealed strong correlations between Phaeocystis and picoeukaryotes with SAR11, SAR116, Magnetospira, and Planktomarina. In contrast, most Thalassiosira operational taxonomic units showed the highest correlations with Polaribacter, Sulfitobacteria, Erythrobacter, and Sphingobium, while Fragilariopsis, Haslea, and Thalassionema were correlated with OM60, Fluviicola, and Ulvibacter. Our in-situ observations suggest distinct associations between phytoplankton and bacterial taxa, which could play crucial roles in nutrient cycling in the Southern Ocean.
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  • 文章类型: Journal Article
    生态学的主要目标是确定自然界中物种丰度的决定因素。体型已经成为丰度的基本和可重复预测指标,较小的有机体比较大的有机体数量更多。生物地理组成部分,被称为伯格曼的规则,描述了优势,跨分类组,寒冷地区的大型生物。虽然不可否认的重要,体型在多大程度上是这些模式的关键特征尚不清楚.我们在硅藻中探索了这些问题,单细胞藻类因其在碳固定和通过海洋食物网的能量流动中的作用而具有全球重要性。使用来自全球分布的单一谱系的系统基因组数据集,我们发现身体大小(细胞体积)与基因组大小密切相关,不同物种之间的差异是50倍,并且是由重复DNA数量的差异驱动的。然而,定向模型识别温度和基因组大小,不是单元格大小,对最大人口增长率的影响最大。一个全球元编码数据集进一步确定了基因组大小是海洋物种丰度的强大预测指标,但只有在高纬度和低纬度的寒冷地区,大基因组的硅藻占主导地位,符合伯格曼规则的模式。尽管物种丰度是由无数相互作用的非生物和生物因素决定的,基因组大小是一个非常强的丰度预测指标。一起来看,这些结果突出了一个新兴性状的宏观进化变化的级联细胞和生态后果,基因组大小,有机体最基本和不可约的特性之一。
    A principal goal in ecology is to identify the determinants of species abundances in nature. Body size has emerged as a fundamental and repeatable predictor of abundance, with smaller organisms occurring in greater numbers than larger ones. A biogeographic component, known as Bergmann\'s rule, describes the preponderance, across taxonomic groups, of larger-bodied organisms in colder areas. Although undeniably important, the extent to which body size is the key trait underlying these patterns is unclear. We explored these questions in diatoms, unicellular algae of global importance for their roles in carbon fixation and energy flow through marine food webs. Using a phylogenomic dataset from a single lineage with worldwide distribution, we found that body size (cell volume) was strongly correlated with genome size, which varied by 50-fold across species and was driven by differences in the amount of repetitive DNA. However, directional models identified temperature and genome size, not cell size, as having the greatest influence on maximum population growth rate. A global metabarcoding dataset further identified genome size as a strong predictor of species abundance in the ocean, but only in colder regions at high and low latitudes where diatoms with large genomes dominated, a pattern consistent with Bergmann\'s rule. Although species abundances are shaped by myriad interacting abiotic and biotic factors, genome size alone was a remarkably strong predictor of abundance. Taken together, these results highlight the cascading cellular and ecological consequences of macroevolutionary changes in an emergent trait, genome size, one of the most fundamental and irreducible properties of an organism.
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  • 文章类型: Journal Article
    从2022年2月至2023年1月,在热带中子河中对低潮(LT)和高潮(HT)期间的浮游植物动态进行了比较评估,Manori,孟买,印度。总的来说,记录了124种浮游植物。HT导致比LT(102种)更大的物种丰富度(124种)和多样性指数(香农-维纳指数)。Pielou的均匀度(J\')和Simpson的优势指数(1-D)没有显示出潮汐的显着波动,因为海洋浮游植物物种随着潮汐而有节奏地进出小溪。总的来说,季节性丰度在季风前的HT(5.79×103u/L)最高,在季风中的LT(0.45×103u/L)最低,而空间丰度在HT的S1处最大(HT-4.04×103u/L),在LT的S3处最低(LT-0.75×103u/L)。硅藻的丰度(HT为1.83×103u/L和3.82×103u/L)和多样性(LT为77,HT为92)占主导地位。诸如Coscinosdiscuscentralis之类的物种,Coscinodiscusgranii,Coscinodiscusradiatus,TriopsFurca,Melosiravarians,Nitzchsiapalea,Chaetocerosaffinis,骷髅marinoi,Stephanocyclusmeneghinianus,小溪中主要的原生居民是浮游菌和肉芽肿。SIMPER分析表明,最大的相似性是在季风期间(47.65%),最小的是在LT季风前期间(38.10%)。然而,在HT中,浮游植物的最大相似性转移到季风后(63.85%),季风前最小(46.71%)。丰富度(d\')和香农多样性(H\')的平均值显示系统中浮游植物的多样性中等。典型对应分析表明,环境参数(水温>pH>硝酸盐>盐度>DO>Alk>硅酸盐)对潮汐浮游植物群落的分布影响较大。因此,已经发现,潮汐在中子河环境中浮游植物群落的分布和丰度中起着重要作用。
    A comparative assessment of phytoplankton dynamics during low tide (LT) and high tide (HT) was conducted from February 2022 to January 2023 in a tropical mesotidal creek, Manori, Mumbai, India. In total, 124 phytoplankton species were recorded. The HT resulted in greater species richness (124 species) and diversity indices (Shannon-Wiener\'s index) than the LT (102 species). The Pielou\'s evenness (J\') and Simpson\'s dominance index (1-D) did not show significant fluctuations with the tides due to the marine phytoplankton species moving rhythmically in and out of the creek with the tides. Overall, the seasonal abundance was maximum during pre-monsoon at HT (5.79 × 103 u/L) and lowest in monsoon at LT (0.45 × 103 u/L), whereas spatial abundance was maximum at S1 (HT- 4.04 × 103 u/L) at HT and lowest at S3 (LT- 0.75 × 103 u/L) at LT. The diatoms dominated in their abundance (1.83 × 103 u/L and 3.82 × 103 u/L in HT) and diversity (77 in LT and 92 in HT). The species such as Coscinodiscus centralis, Coscinodiscus granii, Coscinodiscus radiatus, Triops furca, Melosira varians, Nitzchsia palea, Chaetoceros affinis, Skeletonema marinoi, Stephanocyclus meneghinianus, Planktoniella sol and Skeletonema costatum were the dominant native residents in the creek. SIMPER analysis revealed that the maximum similarity was during the monsoon (47.65%), and the minimum was during the pre-monsoon (38.10%) at LT. However, in HT, the maximum similarity of phytoplankton shifted to post-monsoon (63.85%) and the minimum during the pre-monsoon (46.71%). The mean value of richness (d\') and Shannon\'s diversity (H\') showed a moderate phytoplankton diversity in the system. The environmental parameters (water temperature > pH > nitrate > salinity > DO > Alk > silicate) have a greater influence on the distribution of the phytoplankton community with tides as revealed by the Canonical correspondence analysis. Therefore, it has been found that tides play a significant role in the distribution and abundance of the phytoplankton community in a mesotidal creek environment.
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  • 文章类型: Journal Article
    在北极的架子上,底栖食物网与上覆的初级生产紧密相连。在季节性冰区,交感(与冰相关的)初级生产可能是生产性流入架上底栖动物的主要碳源。然而,交感有机物质的作用在冰层覆盖严重的食物网中不太清楚,生产率低的流出货架,比如格陵兰岛东北部的架子。高度支化的类异戊二烯生物标志物(HBIs)用于跟踪水柱中交感和中上层有机物的相对分布,沉积物,和东北格陵兰陆架和峡湾的底栖动物。整个研究区域的中上层HBI含量较低,表明中上层硅藻的产量普遍较低(在采样时)。这反映在底栖生物上,据估计,它们的约90%的同化碳来自交感神经源,表明底栖食物网高度依赖同情生产。沿海地区的这种依赖程度高于开放式架子,潜在的更高的中上层生产力和河岸上较浅的水可能会增加中上层有机物的贡献。由于预计北极架子上的冰盖减少和快速下沉的冰藻产量减少,可能会导致冰藻与底栖动物之间的耦合减弱,可能对未来的底栖群落结构和功能产生影响。
    On Arctic shelves, benthic food-webs are tightly linked to overlying primary production. In the seasonal ice zone, sympagic (ice-associated) primary production can be a major source of carbon for the benthos on productive inflow shelves. However, the role of sympagic organic matter is less well-understood in food webs of heavily ice-covered, less- productive outflow shelves, such as the northeast Greenland shelf. Highly branched isoprenoid biomarkers (HBIs) were used to track the relative distribution of sympagic and pelagic organic matter in the water column, sediments, and benthic fauna of the northeast Greenland shelf and fjords. Low pelagic HBI presence throughout the study area indicated a generally low production by pelagic diatoms (at the time of sampling). This was reflected in the benthos, as ~90% of their assimilated carbon was estimated to come from sympagic sources, indicating a benthic food-web highly reliant on sympagic production. This reliance was higher in coastal areas than on the open shelf, where the potentially higher pelagic productivity and shallower water on banks likely increased contributions of pelagic organic matter. As declining ice cover and reduced production of fast-sinking ice algae projected for Arctic shelves will likely result in weaker coupling between ice algae and the benthos, with possible consequences for future benthic-community structure and function.
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  • 文章类型: Journal Article
    海洋热浪(MHW)的频率正在增加,持续时间和强度,破坏全球海洋生态系统。虽然大多数报告的影响发生在热带地区,新西兰在2022年经历了最强和最长的MHW,深刻影响了海洋海绵。海绵对岩石底栖海洋群落至关重要,它们的丰度影响着生态系统的功能。这项研究检查了这种MHW对Fiordland的光合海绵Cymbastellalamellata的影响,新西兰。我们描述的程度,生理反应,死亡率,微生物群落变化及该MHW对板岩的生态影响。FiordlandMHW的最高温度比平均水平高4.4°C,持续259天漂白发生在>90%的C.lamellataFiordland种群中。人口规模超过6600万,从5到25米,使这成为有史以来最大的漂白事件。我们将光合共生体鉴定为硅藻,漂白的海绵降低了光合效率。2023年MHW后的调查发现,采样点超过50%的海绵已经死亡,但其余的海绵大部分已经从早期的漂白中恢复。使用模拟MHW实验,我们发现温度压力是坏死而不是漂白的驱动因素,尽管在野外很少观察到坏死(<2%的海绵)。这表明漂白可能不是直接死亡的原因。我们还发现了存活海绵中的微生物群落变化,我们提出的这代表了微生物介导的对MHW的适应性反应。我们还发现C.lamellata是水柱中溶解有机碳的关键贡献者,它们的损失可能会影响生态系统的功能。我们证明了MHW在温带地区破坏关键海洋门的潜力,强调全球温带海绵对MHW的易感程度。
    Marine heatwaves (MHWs) are increasing in frequency, duration and intensity, disrupting global marine ecosystems. While most reported impacts have been in tropical areas, New Zealand experienced its strongest and longest MHW in 2022, profoundly affecting marine sponges. Sponges are vital to rocky benthic marine communities, with their abundance influencing ecosystem functioning. This study examines the impact of this MHW on the photosynthetic sponge Cymbastella lamellata in Fiordland, New Zealand. We describe the extent, physiological responses, mortality, microbial community changes and ecological impact of this MHW on C. lamellata. The Fiordland MHW reached a maximum temperature of 4.4°C above average, lasting for 259 days. Bleaching occurred in >90% of the C. lamellata Fiordland population. The population size exceeded 66 million from 5 to 25 m, making this the largest bleaching event of its kind ever recorded. We identified the photosynthetic symbiont as a diatom, and bleached sponges had reduced photosynthetic efficiency. Post-MHW surveys in 2023 found that over 50% of sponges at sampling sites had died but that the remaining sponges had mostly recovered from earlier bleaching. Using a simulated MHW experiment, we found that temperature stress was a driver of necrosis rather than bleaching, despite necrosis only rarely being observed in the field (<2% of sponges). This suggests that bleaching may not be the cause of the mortality directly. We also identified a microbial community shift in surviving sponges, which we propose represents a microbial-mediated adaptive response to MHWs. We also found that C. lamellata are key contributors of dissolved organic carbon to the water column, with their loss likely impacting ecosystem function. We demonstrate the potential for MHWs to disrupt key marine phyla in temperate regions, highlighting how susceptible temperate sponges globally might be to MHWs.
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  • 文章类型: Journal Article
    在生物经济和循环经济的框架下,废水污泥(WS)可能是其在农业中用作肥料的良好候选者,由于其有机物含量高,N和P,但另一方面,它充满了重金属等有毒物质,微塑料,洗涤剂,抗生素,等等,可以以渗滤液的形式到达地下水和水体。在这项研究中,我们研究了不同污泥浓度的洗脱液形式,在两种不同的淡水生物Selenastrumcapricornutum和Daphniamagna上结合而不与PVC结合,使用生态毒性测试。在端点,我们已经评估了抑制增长率,氧化应激,和色料的生产,而在麦格纳的情况下,我们已经评估了生物体的固定和发育。从我们的结果来看,发现在较高的WS浓度下,没有抑制生长速率,在氧化应激时,在用WS和PVC处理的藻类中,它更高。用0.3g/L污泥和PVC处理的藻类显示出较高的Chl-a产量,其中用0.3g/LWS处理的藻类记录到较高的色素产量。与藻类相比,麦格纳表现出相反的趋势,其中在提供的最高WS浓度下,对应于死亡率增加,被解释为最高的不动百分比。实践要点:废水污泥在农业中用作肥料。测试了PVC微塑料的存在和相关的生态毒性。PVC的存在增加了辣椒中的氧化应激。D.magna受污泥浓度的显著影响。
    In the frame of bioeconomy and circular economy, wastewater sludge (WS) could be a good candidate for its use in agriculture as fertilizer, due to its high content of organic matter, N and P, but on the other hand, it is full of toxicants such as heavy metal, microplastics, detergent, antibiotics, and so on that can reach groundwater and water bodies in leachate form. In this study, we have investigated different sludge concentrations in the eluate form, combined and not with PVC on two different freshwater organisms Selenastrum capricornutum and Daphnia magna, using ecotoxicity tests. At the endpoint, we have evaluated inhibition growth rate, oxidative stress, and pigments production for S. capricornutum, while in case of D. magna, we have assessed organism immobilization and development. From our results, it emerged that at the higher WS concentration, there was not inhibition growth rate, while at oxidative stress, it was higher in algae treated with WS and PVC. Higher Chl-a production was shown for algae treated with 0.3 g/L of sludge coupled with PVC, where higher phaeopigments production were recorded for algae treated with 0.3 g/L of WS. D. magna has shown an opposite trend when compared with algae, where at the highest WS concentrations supplied was corresponding to an increased mortality explaned as the highest immobility percentage. PRACTITIONER POINTS: Wastewater sludge is used in agriculture as fertilizer. PVC microplastic presence and associate ecotoxicity was tested. PVC presence increased oxidative stress in S. capricornutum. D. magna was significantly affected by sludge concentrations supplied.
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  • 文章类型: Journal Article
    增加氮磷排放和减少沉积物输入使硅(Si)成为河口硅藻的限制元素。营养结构的干扰和盐度波动会极大地影响河口硅藻对金属的吸收。然而,尚未评估Si和盐度对这些硅藻中金属积累的综合影响。在这项研究中,我们的目的是研究盐度和硅的有效性如何结合起来影响广泛分布的硅藻Phaeodactylumtricornutum对金属的吸附。我们的数据表明,海水中充足的Si和低盐度可以增强镉和铜在硅藻表面的吸附。在单细胞层面,表面电位是决定金属吸附的主要因素,而表面粗糙度也有助于较高的金属负载能力在较低的盐度。采用无创微测技术的组合,原子力显微镜,X射线光电子能谱,和傅里叶变换红外光谱,我们证明,嵌入硅藻细胞壁中的官能团的多样性和丰度随盐度和Si供应而变化。这导致细胞表面电位的变化和瞬时金属流入。我们的研究提供了新的机制来解释模型河口硅藻的高度可变的金属吸附能力。
    Increasing nitrogen and phosphorus discharge and decreasing sediment input have made silicon (Si) a limiting element for diatoms in estuaries. Disturbances in nutrient structure and salinity fluctuation can greatly affect metal uptake by estuarine diatoms. However, the combined effects of Si and salinity on metal accumulation in these diatoms have not been evaluated. In this study, we aimed to investigate how salinity and Si availability combine to influence the adsorption of metals by a widely distributed diatom Phaeodactylum tricornutum. Our data indicate that replete Si and low salinity in seawater can enhance cadmium and copper adsorption onto the diatom surface. At the single-cell level, surface potential was a dominant factor determining metal adsorption, while surface roughness also contributed to the higher metal loading capacity at lower salinities. Using a combination of non-invasive micro-test technology, atomic force microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, we demonstrate that the diversity and abundance of the functional groups embedded in diatom cell walls vary with salinity and Si supply. This results in a change in the cell surface potential and transient metal influx. Our study provides novel mechanisms to explain the highly variable metal adsorption capacity of a model estuarine diatom.
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