排序方式： 共有11条查询结果，搜索用时 187 毫秒
1.
Acrochaete leptochaete (Huber) Nielsen (Chaetophoraceae, Chlorophyta) was isolated from the macroalgae Chaetomorpha collected from intertidal pools in Rongcheng, Shandong, China. 18S rDNA combined with ITS regions were used to ascertain the morphological identification of the isolated material. Based on the unialgal culture, asexual reproduction and growth characteristics of A. leptochaete were investigated over wide ranges of temperature and irradiance. Results revealed that asexual reproduction of A. leptochaete could be realized by biflagellate zoospores. The zoospores germinated directly to give self- replicating generations. Zoospore germination was bipolar. A temperature range from 13-21°C and a lower irradiance of 36 μmol/(m2·s) were most favorable for the growth of A. leptochaete. Thallus organization, an important taxonomic criterion for the genus Acrochaete, was affected markedly by temperature and irradiance. Our results extend the knowledge about the species’ general biology and its morphological plasticity. For classification and identification of a simple microphytic algae like A. leptochaete, which are traditionally placed in the class Chaetophoraceae, we propose that molecular tools associated with culture observations are applied. 相似文献
2.
The marine green alga Chaetomorpha valida fouls aquaculture ponds along the coastal cities of Dalian and Rongcheng, China. Unialgal cultures were observed under a microscope to determine the developmental morphological characters of C. valida. Results reveal that gametophytic filaments often produce lateral branches under laboratory culture conditions, suggesting an atypical heteromorphic life cycle of C. valida between unbranched sporophytes and branched gametophytes, which differs from typical isomorphic alternation of Chaetomorpha species. The shape of the basal attachment cell, an important taxonomic character within the genus, was found variable depending on environmental conditions. The 18S rDNA and 28S rDNA regions were used to explore the phylogenetic affinity of the taxa. Inferred trees from 18S rDNA sequences revealed a close relationship between C. valida and Chaetomorpha moniligera. These results would enrich information in general biology and morphological plasticity of C. valida and provided a basis for future identification of green tide forming algae. 相似文献
3.
4.
Most of reported harmful algal blooms(HABs)of microalgae(75%)have been caused by dinoflagellates.Studies on the negative effects of HABs have generally focused on animals,valuable organisms in particular,and environmental factors such as dissolved oxygen and nutrients,but relatively fewer on community level,particularly that using metagenomic approach.In this study,we reported an investigation on the effects of a HAB caused by the dinoflagellate Prorocentrum donghaiense on the species diversity and community structure of the dinoflagellate sub-community via a pyrosequencing approach for the samples taken before,during,and after the bloom season of P.donghaiense in the East China Sea.We sequenced partial 28S rRNA gene of dinoflagellates for the field samples and evaluated the species richness and diversity indices of the dinoflagellate community,as a sub-community of the total phytoplankton.We obtained 800185 valid sequences(categorized into 560 operational taxonomic units,OTUs)of dinoflagellates from 50 samples and found that the biodiversity of dinoflagellate community was significantly reduced during the blooming period in comparison to that in pre-and after-blooming periods,as reflected in the four diversity indices:the species richness expressed as the number of OTUs,Chao1 index,Shannon index(evenness),and Gini-Simpson index.These four indices were all found to be negatively correlated to the cell density of the bloom species P.donghaiense.Correlation analyses also revealed that the P.donghaiense cell abundance was correlated negatively with NO3--N,and NO2--N,but positively with total nitrogen(TN)and total phosphorus(TP).Principal coordinates analysis(PCoA)showed that the community structure of dinoflagellates was markedly different among the different sampling periods,while the redundancy analysis(RDA)revealed P.donghaiense abundance,salinity,NO3--N,and SiO32-were the most four significant factors shaping the dinoflagellate community structure.Our results together demonstrated that HABs caused by the dinoflagellate P.donghaiense could strongly impact the aquatic ecosystem on the sub-community level which the blooming species belongs to. 相似文献
5.
船舶压舱水可引起外来生物入侵，国际海事组织(International Maritime Organization, IMO)因此制定了具有约束力的压舱水公约，已于2019年1月对我国正式生效。大量研究证明船舶压舱泥是有害藻华种类特别是有害甲藻孢囊的携带者。另一方面，有害藻华在我国近三十年频发，尤其是新的种类不断出现。因此，这种态势是否与压舱泥带来的外来种入侵有关是一个具有重要科学和现实意义的问题。我们最近的工作表明，此前国内外通过形态学方法对压舱泥的检测都大大地低估了甲藻孢囊的种类多样性和样品间种类组成的异质性。因此，必须通过更深入全面的实证研究对外源有害藻华甲藻通过压舱泥入侵我国海域进行风险评估。本文从如下几个方面进行了综述与讨论：(1) 船舶压舱水(泥)与有害藻华地理扩散；(2) 国内外有关压舱泥中甲藻孢囊多样性的检测与溯源研究；(3) 我们对美国港口船舶压舱泥的检测发现压舱泥中甲藻孢囊具有很高的种类多样性和样品间的异质性。最后从我们最近的工作及与文献报道的工作比较获得了几个重要的科学问题。在评述国内外研究成果和前期研究结果基础上，提出有必要通过更大量、广泛的国际船舶压舱泥和中国全海域沉积物取样、高通量测序的分子鉴定与形态观察、单孢囊分子-形态鉴定、孢囊萌发、全面生信分析相结合的技术路线，实证性地评估有害藻华种类通过压舱泥入侵中国的风险，并以此建立对新出现藻华种类溯源或判断是否外来种入侵的基本依据，同时为海关职能部门的检验执法提供依据。 相似文献
6.
生活史(休眠孢囊)作为甲藻有害藻华年际频发和地理扩散的一种关键机制的研究进展 总被引：2，自引：0，他引：2
过去几十年,中国近海有害藻华的发生频率、规模和面积不断增大, 对我国水产养殖业、渔业和近岸生态系统造成了重大损失和威胁。 在引起有害藻华的众多原因中,藻华甲藻的特殊生活史策略,尤其是形成休眠孢囊,提供了一种关键的机理,因为孢囊的形成过程常伴随着基因重组从而增加了藻华藻的生态适应性;孢囊厚的囊壁增加了其对不利环境条件的耐受性;厚的囊壁使其免于病原体感染和捕食攻击;孢囊的适时萌发为藻华提供了“种源”;孢囊可通过自然或人为原因如船舶压舱水传播从而扩大了其地理分布。我们综述并讨论了甲藻生活史和孢囊研究的如下几个重要方面：１）甲藻生活史的复杂性和有关甲藻孢囊概念及归类的争议;２）沉积物中孢囊“作图（cyst mapping）”在藻华模型和预测（报）中的重要性以及孢囊分布/丰度与藻华规模耦合关系的复杂性和条件依赖性;３）孢囊形成和萌发的若干影响因子及其复杂性和可变性;和４）最近些年来分子生物学技术和各种组学手段在甲藻生活史和孢囊研究中的部分应用,特别是植物激素在孢囊形成、萌发过程中的可能作用。在简要评述了国际、国内有关研究历史中的路标性成果后,最后强调了四个值得重视的研究方向。 相似文献
7.
8.
The dinoflagellate genus Margalefidinium has been split from Cochlodinium as a new genus recently and Margalefidinium fulvescens is one of the five Margalefidinium species. Margalefidinium fulvescens is toxic and has been reported from the coastal waters of USA, Canada, Mexico, China, Japan, Indonesia, Korea, Pakistan and Spain. Here we provide the morphological and phylogenetic characterization for an isolate of it from the Jiaozhou Bay, Qingdao, China. Our results showed that the vegetative cells were subspherical to ellipsoidal, 34–60 μm in length, and 19–41 μm in width. Both single cell forms and colonies in chains of 2, 4, or 8 cells were observed in cultures, but chain forms with 2 or 4 cells were observed more often in the field samples. The cingulum was rather deep, encircling the cell approximately twice, but the sulcus was rather narrow, surrounding the cell about one turn. The nucleus was spherical and located at the central epicone. The chloroplasts were granular, brownish, and scattered peripherally. An orange pigmented body also appeared in the epicone. The apical groove appeared vase-like as previously described. Under epi-fluorescence microscopy, a pumpkin-like structure was clearly observed, in which cells were embedded. Cells were observed to exit from the structure, which led us to a hypothesis that the structure may provide cells a shelter to avoid predation or to respond to other stresses. The phylogenetic analyses based on partial LSU rDNA sequences indicated that M. fulvescens from the Jiaozhou Bay was grouped with M. fulvescens populations from other origins and closely related to the clade of M. polykrikoides.Our morphological observations and phylogenetic analyses together confirmed the presence of M. fulvescens in China and our monitoring has also observed the species dominant in the dinoflagellate community of the Jiaozhou Bay in the early autumn of 2015, which alerted us to continually monitor this bloom-forming species in the region. 相似文献
9.
多环马格里夫藻是一种世界性广泛分布的有毒有害藻华原因种。过去30多年里多环马格里夫藻藻华在许多国家频繁暴发且呈快速扩散趋势。过去的研究根据不同地理来源种群在核糖体大亚基基因序列的显著差别,将其分成4种不同核糖体型(ribotype),即东亚型、菲律宾型、美国/马来西亚型和地中海型。但是,不同核糖体型的种群在形态和超微结构上是否也存在可辨识差异尚未见深入研究。为此,本文对从中国青岛胶州湾、美国东海岸和马来西亚近海分离的三株多环马格里夫藻(中国株MPJZBC3、美国株CP1和马来西亚株MPCoKK23)的细胞表面形态和超微结构进行了比较研究,并进一步基于核糖体大亚基序列进行了分子系统学分析。结果首先证明了分离自胶州湾的多环马格里夫藻属于东亚核糖体型,而美国株和马来西亚株均属美国/马来西亚型(中国株与美国株及马来西亚株在1523个碱基的核糖体大亚基序列上相似性为93.6%)。但是,在所有常用的具有分类学意义的细胞形态学和超微结构特征上[细胞大小、单细胞或群体及群体细胞数、上下锥形状、横沟位移度(绕细胞圈数)、纵沟形态、顶沟形态、细胞核位置与形状、染色体形状与数目、叶绿体的形状、结构、数目及分布、淀粉核形态等],中国株与美国株和马来西亚株(也即东亚核糖体型和美国/马来西亚核糖体型)都没有明显可区分的差别。因此,我们认为应该在生活史、休眠孢囊形态和生理学特征(如毒素种类及毒性强弱)以及性别相容性(sexualcompatibility)等方面开展进一步比较研究,以获得对不同核糖体型种群的识别性状。在现阶段有害藻华的野外监测中,尤其是对于不同核糖体型种群可能造成的生物入侵的监测和追溯,多环马格里夫藻的鉴定尚必须以核糖体基因序列作为可靠的判决依据。 相似文献
10.
本文首次对分离于我国广西北部湾的一株棕囊藻(Phaeocystis)纯培养进行了形态学研究。通过对其核糖体大亚基序列(LSU rDNA)进行了系统进化分析,并运用光学显微镜、扫描电镜和透射电镜等,对该藻的游动单细胞和囊体细胞表面结构和超微结构进行了详细的观察。结果表明,通过分子序列和形态学特征确证了该纯培养为球形棕囊藻(Phaeocystisglobosa)。通过分子系统进化分析,从北部湾获得的球形棕囊藻与同属的P. antarctica和P. rex的亲缘关系较近,但与P. jahnii的亲缘关系相对较远。我们发现该藻至少有两种类型的细胞:具鞭毛游动细胞和无鞭毛囊体细胞,其大小分别为2.30—3.98μm和3.69—6.49μm。具鞭毛游动细胞表面具有1—2个位置不固定但形状较为规则的圆盘状凸起,细胞表面的鳞片大小无明显差别;囊体细胞均匀地分布在囊体上,囊体细胞表面光滑,有三个较短的附属物。具鞭毛游动细胞和囊体细胞有2个或4个叶绿体,具鞭毛游动细胞的细胞核位于细胞的中下部,而囊体细胞的细胞核则位于细胞的中上部。细胞分泌物在扫描电镜样品处理过程后形成多数与细胞相连的丝状物,且丝状物形成较为规则的五角星形结构,每个角与一根丝相连,有些丝状体上有"瘤状"结构。研究结果填补了我国在球形棕囊藻形态学和超微结构研究上的空白,为深入认识其生物学特征及其成囊机理提供基础。 相似文献