海链藻属重要形态学特征的二次研究——以艾伦海链藻为例

海链藻属（Thalassiosira Cleve）是硅藻门中物种多样性最为丰富的大属之一,广泛分布于全球各类水体。目前沿用的海链藻属分类体系是基于形态特征建立的,尤其是电镜下的超微特征具有重要的分类价值。然而,也有研究认为某些形态特征存在不稳定或变化的情况,应对其开展二次研究和重新评估。故此,本文选择全球近岸广布种艾伦海链藻（T.allen Takano）作为典型代表,基于建立的单克隆培养株系,结合传统形态学方法和现代分子生物学技术,对其重要形态特征进行了二次研究。结果显示：（1）艾伦海链藻壳面孔纹的排列方式存在一定的变化,呈切线形或偏心状;壳缘唇形突的位置多有变化,占据一个壳缘支持突的位置、或位于两个壳缘支持突正中间、或靠近其中一个。艾伦海链藻这两个特征并不具有较高的稳定性,其分类学意义或应降低;（2）壳缘不具有肋纹,此特征相对稳定,可作为艾伦海链藻的识别特征之一;（3）艾伦海链藻具有较保守的遗传多样性,尚未发现（拟）隐形种。结合其它海链藻的形态学报道,我们认为孔纹排列方式易受环境的影响,稳定性较差,在分类时应慎重应用;壳缘唇形突的位置在少数海链藻属物种中易发生变化,分类时应视具体物种而针对性应用;支持突等突起特征较为稳定,在海链藻属物种的分类体系中仍可作为重要依据;艾伦海链藻中壳缘肋纹具有较好的稳定性,可作为分类依据,但在其它海链藻属物种中是否也具有很好的分类价值,还需要更多的研究加以验证;分子信息在形态特征上的二次研究和评价中具有重要应用价值,但目前相关分子数据的缺乏和不足限制了对其进一步的研究。本研究对重新评估艾伦海链藻形态特征的分类学价值、完善现存的分类学体系提供了参考。     

小字海链藻双卫变种,海链藻属一新变种

采用毛细管复洗技术建立海链藻属(Thalassiosira)物种的单克隆培养株系,结合形态学和分子系统学研究,对小字海链藻原变种(Thalassiosira minuscula var.minuscula Krasske)的形态特征进行观察,并报道了1个新变种:小字海链藻双卫变种(T.minuscula var.bicustodis X.H.Guo,Y.Q.GuoY.Li)。双卫变种与原变种的形态特征基本一致,区别仅在于唇形突的伴生支持突数目不同,双卫变种具有2个,原变种只有1个。基于对多个株系生活史的连续观察,确认其伴生支持突的数目稳定,具有分类学意义。     

我国沿海双唇形突海链藻的形态学研究

唇形突是海链藻中常见的一类突起, 其形态学特征和排列方式是重要的分类学依据。绝大多数海链藻只有一个唇形突, 两个唇形突的现象仅报道于极少数海链藻种类。我国关于双唇形突海链藻的报道较少。研究利用扫描电镜(SEM)技术, 对采自我国沿海海域的自然水样, 以及分离获得的单克隆培养藻株进行了形态学观察, 针对其中的海链藻属Thalassiosira Cleve种类开展了形态学的专题研究。报道了4个具有双唇形突的海链藻种类, 分别是有翼海链藻T. bipartita (Rattray) Hallegraeff、脆弱海链藻T. fragilis Fryxell、亨氏海链藻T. hendeyi Hasle &; Fryxell和维斯吉思海链藻T. visurgis Hustedt, 其中有3个为我国新记录种类: 脆弱海链藻、亨氏海链藻和维斯吉思海链藻。对每个种类的形态学特征、生活习性和生态分布进行了描述, 提供了扫描电镜照片, 对相似种类的形态学特征进行了比较研究, 分析了唇形突的变化类型及其分类学价值。     

小盘藻属，我国微型硅藻类的一个新记录属

本文描述了我国首次记录的小盘藻属Minidiscus硅藻四种。主要特征是壳缘无环突起,壳面上 的支持突和1个唇形突均远离壳缘。小盘藻M．trioculatus,奇特小盘藻M．comicus和智利小盘藻M．chilensis为我国的新记录;细弱小盘藻M．subtilis为新种。它们的主要区别在于壳面花纹及支持突和唇形突排列方式的不同。     

海链藻(Thalassiosira)与圆筛藻(Coscinodiscus)的形态学比较研究

海链藻属（Thalassiosira）和圆筛藻属（Coscinodiscus）的种类繁多,是硅藻门中的大属和代表属。两者的形态学特征具有较多相似之处,易混淆鉴定。通过光学显微镜和电镜观察,比较研究了海链藻和圆筛藻种类的形态学特征。海链藻种类除了具有1~2个唇形突之外,还具有数量较多的支持突,少数种类具有闭合突;筛膜位于壳面内侧;中孔在壳面外侧。而圆筛藻种类只具有数量众多的唇形突,且其中两个较大;筛膜位于壳面外侧;中孔在壳面内侧。由于两属形态学特征的区别只有在电镜下才能清晰观察到,因此尚有较多的分类修订工作需要进行。     

海链藻属一新变种艾伦海链藻肋纹变种

为了澄清海链藻属Thalassiosira的物种多样性, 采用毛细管复洗技术建立了单克隆培养株系。利用光镜和扫描电镜观察形态学特征, 并扩增其核糖体小亚基和大亚基序列, 用于分子系统树的构建。结合形态学和分子系统学数据, 发现艾伦海链藻株系之间存在一定的形态差异和遗传多样性。经过与原始文献的比对, 确认了艾伦海链藻原变种的特征, 并报道了该种的一个新变种艾伦海链藻肋纹变种Thalassiosira allenii var. striata X. H. Guo, Y. Q. Guo & Y. Li。该变种与原变种的形态特征基本相似, 区别在于壳面边缘具有肋纹结构, 原变种则无。基于核糖体小亚基和大亚基的系统树均显示, 肋纹变种与原变种聚在同一个分支上, 形成姐妹支(BPP>0.90), 表明两者之间具有最近的亲缘关系。2个变种的核糖体小亚基序列完全一致, 没有碱基差异。但用于分析的556个核糖体大亚基序列中, 两者存在11个差异碱基, 遗传距离为0.01。     

我国沿海闭合突海链藻的形态学研究

闭合突是一类特殊的突起, 仅报道于少数海链藻种类, 其形态学特征和排列方式是重要的分类学依据。我国关于闭合突海链藻的报道较少。研究利用扫描电镜(SEM)技术, 对采自我国沿海海域的自然水样, 以及分离获得的单克隆培养藻株进行了形态学观察, 针对其中的海链藻属Thalassiosira Cleve种类开展了形态分类学的专题研究。报道了5个具有闭合突的海链藻种类, 分别是西达礁海链藻T. cedarkeyensis Prasad、偏心海链藻T. eccentrica (Ehrenberg) Cleve、伦德海链藻T. lundiana Fryxell、细孔海链藻T. punctigera (Castracane) Hasle和管状海链藻T. tubifera Fryxell, 其中有3个为我国新记录种类: 西达礁海链藻、细孔海链藻和管状海链藻。对每个种类的形态学特征和生境进行了描述, 提供了扫描电镜照片, 对相似种类的形态学特征进行了比较研究, 分析了突起特征的变化类型及其分类学价值。       

我国沿海线形亚属海链藻的形态学研究

壳面孔纹的形态学特征是海链藻的重要分类学依据之一。线形亚属的海链藻种类大多是从圆筛藻属修订而来, 它们之间的区别特征细微, 需电镜下观察才能准确鉴定。我国关于线形亚属海链藻的报道较少。研究利用电镜(EM)技术, 对采自我国沿海海域的自然水样, 以及分离获得的单克隆培养藻株进行了形态学观察, 针对其中的海链藻属Thalassiosira Cleve种类开展了形态分类学的专题研究。报道了6个隶属于线形亚属的海链藻种类, 分别是紧密海链藻T. densannula Hasle &; Fryxell、微小海链藻T. exigua Fryxell &; Hasle、线形海链藻T. lineata Jousé、微线形海链藻T. nanolineata (Mann) Fryxell &; Hasle、结线形海链藻T. nodulolineata (Hendey) Hasle &; Fryxell和柔弱海链藻T. tenera Proschkina-Lavrenko, 其中有4个为我国新记录种类: 紧密海链藻、线形海链藻、微线形海链藻和结线形海链藻。对每个种类的形态学特征、生活习性和生态分布进行了描述, 提供了电镜照片。对相似种类的形态学特征进行了比较研究, 分析了孔纹特征的变化类型及其分类学意义。     

闽南-粤东近海上升流区花水母亚纲一新属二新种记述(丝螅水母目,原帽水母科;头螅水母目,棒状水母科)

记述了闽南-粤东近海上升流区花水母亚纲原帽水母科Protiaridae Haeckel,1879裸球拟海帽水母1新种Halitiarella nudibulbus Xu,Huang et Guo,sp.nov.与棒状水母科Corymorphidae Allman,1872张氏八辐端粗水母1新属1新种Octovannuccia zhangjinbiaoi Xu,Huang et Lin,gen.nov.,sp.nov.。模式标本保存在国家海洋局第三海洋研究所。裸球拟海帽水母,新种Halitiarella nudibulbus Xu,Huang et Guo,sp.nov.(图1～2)鉴别特征水母伞无顶突,外伞有分散刺胞;伞缘有4条主辐位触手和4个间辐位缘基球,所有触手和缘基球有背轴眼点;主辐位触手与间辐位缘基球间具2～3条短的实心缘丝。正模(TS045)和副模(TS046-049),闽南-粤东上升流区A25站(22.8°N,118.1°E),水深32m,2009-06-11,项鹏采(第三海洋研究所)。词源:新种以拉丁词nudibulbus为种名,意为裸球,指该种间辐位缘基球无触手。八辐端粗水母,新属Octova...     

中国土天牛属雄性外生殖器研究(鞘翅目,天牛科,锯天牛亚科,锯天牛族)

对中国土天牛属13种雄性外生殖器进行了解剖研究,总结了土天牛属的雄性外生殖器特征。在所研究的5个亚属中,仅Dorysthenes(Prionomimus)亚属内各种类具有很多共同的特征,其中包括与其他种不同的雄性外生殖器特征。所研究的13种雄性外生殖器在形态上存在差异,利用交配孔背缘中央是否低于两侧、交配孔腹缘肩部的倾斜程度、阳基侧突的长度和中茎的弯曲程度等雄性外生殖器特征能够很好地对土天牛属的种类进行鉴定,尤其是鉴定外部形态十分相似的种类。     

Morphology and molecular phylogeny of Thalassiosira sinica sp. nov. (Bacillariophyta) with delicate areolae and fultoportulae pattern

Thalassiosira Cleve is one of the most species-rich marine diatom genera. Previous studies have mainly focused on polar and temperate areas, but recent studies on material from Asian waters suggested that a high and undescribed species diversity of Thalassiosira occurs in Asia. On the basis of plankton samples collected from the South China Sea, a new species, T. sinica sp. nov. Y. Li & Y. Q. Guo is described. The morphology of the cells was examined by light and scanning electron microscopy. The hypervariable region of the nuclear large-subunit ribosomal DNA and the relatively conserved region of the nuclear small-subunit ribosomal DNA were sequenced for information on phylogenetic relationships. The living cells are usually solitary and drum-shaped. The areolae on the valve are delicate, small and arranged in fascicles. In addition to a regular ring of marginal fultoportulae on the valve edge, T. sinica possesses one central fultoportula and a number of fultoportulae arranged into 2–3 irregular rings on the valve face. A rimoportula located inside the ring of marginal fultoportulae possesses a long and strong external tube. The valvocopula and the copulae have rows of pores, but the pores on the valvocopula are larger than those on the copulae. Thalassiosira sinica appears to be included in subgroup C sensu Gedde because of a rimoportula with a distinct external tube located on the valve face. The molecular phylogeny, inferred from both SSU and LSU sequences, does, however, not support the validity of subgroup C, as the closest allies of T. sinica here turned out to be T. diporocyclus and T. lundiana, species in which the rimoportulae are located on the valve margin.     

广东沿海洛氏角毛藻复合群物种多样性的探究

为了澄清洛氏角毛藻复合群的物种多样性, 并明确洛氏角毛藻和并基角毛藻的种间界限, 文章以广东沿海为例, 建立了洛氏角毛藻复合群的22个单克隆培养株系, 利用光学显微镜和电子显微镜技术, 开展了基于生活史的连续形态学观察; 结合基于核糖体大亚基编码基因D1-D3区序列的分子系统学分析。结果表明: 文章支持近年研究的观点, 认为“角毛基部并行融合”不是稳定特征, 不宜继续作为并基角毛藻的标志特征; 发现洛氏角毛藻形态相似藻株聚类在2个分支上, 确认了洛氏角毛藻确实存在隐藏的物种多样性。其中一类与目前认知的洛氏角毛藻最为接近, 而另一类在角毛孔纹、休眠孢子上存在明显区别。经过对洛氏角毛藻历史文献的对比研究, 发现洛氏角毛藻的物种界定存在混乱和模糊的情况, 如休眠孢子形态, 及其初生壳面是否具有二叉状分布结构等, 均存在相互矛盾或不一致的历史报道。     

PHYLOGENETICS OF THE LISIANTHIUS SKINNERI (GENTIANACEAE) SPECIES COMPLEX IN PANAMA UTILIZING DNA RESTRICTION FRAGMENT ANALYSIS

The well-delimited and evolutionary interesting tropical shrub group, the Lisianthius skinneri (Gentianaceae) species complex, was analyzed for variation in nuclear ribosomal DNA and chloroplast DNA by restriction endonuclease fragment analysis. A most parsimonious tree using variations in both DNAs was constructed for seven populations in the group by including an appropriate outgroup. This phylogeny is significantly more compatible with the DNA data than most, but not all, less parsimonious phylogenies. At least two distinct lineages have independently evolved geographically restricted, cloud forest species from the putative ancestral, widespread, and lower elevation L. skinneri. Lisianthius skinneri itself is shown to be paraphyletic with populations derived separately from the two distinct lineages. Except for a switch in the placement of two populations, this DNA-based phylogeny is congruent with an isozyme-based Wagner network depicting relationships in the species complex. Relative rates of divergence, in terms of nuclear ribosomal DNA, chloroplast DNA, isozymes, and morphology, differ markedly within and between lineages. The non-transcribed spacer region of ribosomal DNA is shown to evolve in a manner that is not in accord with a molecular clock hypothesis. Small population sizes, restricted and isolated nature of populations, and probable founder events are suggested as instrumental in causing this lack of concerted divergence within and between lineages of the L. skinneri species complex.     

中国热带地区半知菌III.(英)

本文报道采自广东热带地区的15种半知菌,其中有4个新种和2个中国新记录种:寄生在毛麝香 Adenosma glutinosum (L.) Druce上的毛麝香假尾孢 Pseudocercospora adenosmae Y. L. Guo,生于柑橘属Citrus sp.植物上的柑橘假尾孢 P. citri Y. L. Guo,生于木防己属Cocculus sp.植物上的木防己生假尾孢 P. cocculigena Y. L. Guo,生于腺萼木属Mycetia sp.植物上的腺萼木假尾孢P. mycetiae Y. L. Guo,生于西番莲Passiflora coerulea L.上的西番莲生尾孢Cercospora passifloricola Chupp和生于吴茱萸属Evodia sp.植物锈菌春孢子器上的春孢器生枝孢Cladosporium aecidiicola Th黰.。文中为新种提供了拉丁文简介、英文描述并附图,研究的标本保存在中国科学院微生物研究所菌物标本馆(HMAS)。     

中国石蕊科地衣研究之五中国石蕊属地衣一新种

本文报道了产于中国西南地区的石蕊属地衣一新种:亚厚叶石蕊(Cladoniasubincrassata S.Y.Guo),其主要的次生代谢产物为松萝酸和泽屋菇.文中还从形态、化学和地理分布方面将新种和邻近种厚叶石蕊(Cladonia incrassata)进行了比较.     

Pythium carbonicum,a new species isolated from a spoil heap in northern France,the ITS region,taxonomy and comparison with related species

Pythium carbonicum (F-72) sp. nov. was found in soil samples taken on the top of a spoil heap in northern France. The morphology of this new species resembles that of a recently described species: Pythium megacarpum. However, the antheridial and oogonial characteristics of this new species are unique, and the comparison of its ITS region of the nuclear ribosomal DNA indicates that this species is also related to the genus Phytophthora. The fungus does not sporulate, the sporangia germinate directly into mycelium through germ tubes. The oogonia of P. carbonicum are smooth-walled and also papillated, and are provided with monoclinous and diclinous antheridia that wrap around, forming a complicated knot. Morphological features of this new species, together with the sequences of the ITS region of its nuclear ribosomal DNA and its comparison with related species are discussed here.     

THE MARINE,PLANKTONIC DIATOMS THALASSIOSIRA OCEANICA SP. NOV. AND T. PARTHENEIA1

The diatom clone 13–1 isolated from the Sargasso Sea by Dr. R. R. L. Guillard as Cyclotella nana Hust. or Thalassiosira pseudonana Hasle and Heimdal is described as a separate species, Thalassiosira oceanica sp. nov. An amplified diagnosis of Thalassiosira partheneia Schrader is given, and a comparison of the two species is made based on light and electron microscopy. Similarities are present in the apparent distribution pattern, cell size, and girdle structure. Differences are present in the shape of the areolae of the valvocopula and the copula, in the structure of the vela of these bands, in the texture of the external valve surface, in the morphology of the strutted processes, in the location of the labiate process, in the distance between the marginal strutted processes, and by the presence of a marginal ridge in T. oceanica. Fifteen nanoplanktonic (maximum diameter = 20 UmUm) Thalassiosira species are listed, among them T. oceanica and T. partheneia.     

STRUCTURAL FEATURES OF NUCLEAR GENES IN THE CENTRIC DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)

Thalassiosira weissflogii (Grun.) Fryxell et Hasle is one of the more commonly studied centric diatoms, and yet molecular studies of this organism are still in their infancy. The ability to identify open reading frames and thus distinguish between introns and exons, coding and noncoding sequence is essential to move from nuclear DNA sequences to predicted amino acid sequences. To facilitate the identification of open reading frames in T. weissflogii , two newly identified nuclear genes encoding β-tubulin and t  -complex polypeptide (TCP)-γ, along with six previously published nuclear DNA sequences, were examined for general structural features. The coding region of the nuclear open reading frames had a G + C content of about 49% and could readily be distinguished from noncoding sequence due to a significant difference in G + C content. The introns were uniformly small, about 100 base pairs in size. Furthermore, the 5' and 3' splice sites of introns displayed the canonical GT/AG sequence, further facilitating recognition of noncoding regions. Six of the nuclear open reading frames displayed relatively little bias in the use of synonymous codons, as exemplified by the cDNAs encoding β-tubulin and TCP-γ. Two open reading frames displayed strong bias in the use of particular codons (although the codons used were different), as exemplified by the cDNA encoding fucoxanthin chlorophyll a/c binding protein. Knowledge of codon bias should facilitate, for example, design of degenerate PCR primers and potential heterologous reporter gene constructs.     

PHYLOGENETIC RELATIONSHIPS AMONG ISOLATES OF EUDORINA SPECIES (VOLVOCALES, CHLOROPHYTA) INFERRED FROM MOLECULAR AND BIOCHEMICAL DATA

Phylogenetic analyses of 19 strains representing five species of Eudorina, one strain of Pleodorina indica, and seven strains of Yamagishiella unicocca were carried out by sequencing the internal transcribed spacer region (ITS 1 and ITS 2) of the nuclear ribosomal DNA (rDNA) repeats. The sequence data resolved five phylogenetic groups, one consisting of Y. unicocca and the other four encompassing all the Eudorina species. Two isolates, Eudorina sp. (ASW 05157) and Pleodorina indica (ASW 05153), were of uncertain affiliation. Whereas one monophyletic group included strains of E. elegans only, the other strains of E. elegans appeared alongside E. cylindrica, E. illinoisensis, and E. unicocca var. unicocca in the other Eudorina clades. The distribution pattern of the carotenoid loroxanthin ([3R,3'R,6'R]-β,ε-carotene-3,19,3'-triol), a systematically useful biochemical marker within chlorophycean flagellates, was shown to match the evaluated molecular data. Whereas it was either totally absent or universally present in six of the deduced phylogenetic lines, it occurred randomly in the E. elegans clade containing only E. elegans isolates. The results substantiated the current hypothesis that the unique vegetative morphology of E. elegans has independently arisen at various times during evolution and that it is not a marker of a monophyletic group.