共查询到13条相似文献，搜索用时 15 毫秒
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Lesheng Kong Ryan E. Morse Christopher J. Gobler Michael James Holmes 《Journal of phycology》2012,48(2):455-466
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Light and electron microscopy, nuclear-encoded LSU rDNA sequences, and pigment analyses were performed on five geographically separate isolates of Gymnodinium mikimotoi. The morphological variation between the isolates equals that found within the isolates. The nuclear-encoded LSU rDNA sequences were nearly identical in all isolates, and molecular analyses using maximum likelihood, parsimony, and neighbor joining showed the geographical isolates as an unresolved clade. Based on the available data it is concluded that the European isolates, formerly identified as Gyrodinium aureolum , Gyrodinium cf. aureolum , or Gymnodinium cf. nagasakiense , are conspecific with the Japanese Gymnodinium mikimotoi. An isolate from the Pettaquamscutt River, USA, is suggested to represent what Hulburt (1957) described as Gyrodinium aureolum. The LSU rDNA sequence data and ultrastructural characters in this isolate closely resemble those of Gymnodinium fuscum , the type species of Gymnodinium , and Gyrodinium aureolum Hulburt is therefore renamed Gymnodinium aureolum (Hulburt) G. Hansen, comb. nov. 相似文献
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甲藻环沟藻属于一类无色素体、表面有脊的裸甲藻, 因可捕食一些重要的赤潮生物而在海洋生态系统中扮演着重要的角色。有关中国近海环沟藻属的物种多样性信息非常有限。本文报道了2个新记录种——纺锤环沟藻(Gyrodinium fusiforme)和莫氏环沟藻(G. moestrupii)。纺锤环沟藻细胞呈纺锤形, 长48.0-58.0 μm, 宽18.0-23.0 μm, 长宽比为2.4-3.0, 和模式种相比体型和长宽比都较小。莫氏环沟藻细胞也呈纺锤形, 长约30 μm, 宽约15 μm。我们测定了纺锤环沟藻和莫氏环沟藻大亚基的部分序列, 并根据大亚基序列利用最大似然法和贝叶斯法建立了系统发育树。结果显示环沟藻属是单源的, 纺锤环沟藻和裂缝环沟藻(G. fissum)聚合在一起, 但是与螺旋环沟藻(G. spirale)分离。纺锤环沟藻和莫氏环沟藻分别可以摄食米氏凯伦藻(Karenia mikimotoi)和具齿原甲藻(Prorocentrum dentatum), 前者在米氏凯伦藻赤潮中的大量出现显示它可以促进赤潮的消退。 相似文献
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Miguel F. De Salas Aitor Laza‐Martínez Gustaaf M. Hallegraeff 《Journal of phycology》2008,44(1):241-257
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Annica M. Sundström Anke Kremp Niels Daugbjerg Øjvind Moestrup Marianne Ellegaard Regina Hansen Susanna Hajdu 《Journal of phycology》2009,45(4):938-952
A naked dinoflagellate with a unique arrangement of chloroplasts in the center of the cell was isolated from the northern Baltic proper during a spring dinoflagellate bloom (March 2005). Morphological, ultrastructural, and molecular analyses revealed this dinoflagellate to be undescribed and belonging to the genus Gymnodinium F. Stein. Gymnodinium corollarium A. M. Sundström, Kremp et Daugbjerg sp. nov. possesses features typical of Gymnodinium sensu stricto, such as nuclear chambers and an apical groove running in a counterclockwise direction around the apex. Phylogenetic analyses based on partial nuclear‐encoded LSU rDNA sequences place the species in close proximity to G. aureolum, but significant genetic distance, together with distinct morphological features, such as the position of chloroplasts, clearly justifies separation from this species. Temperature and salinity experiments revealed a preference of G. corollarium for low salinities and temperatures, confirming it to be a cold‐water species well adapted to the brackish water conditions in the Baltic Sea. At nitrogen‐deplete conditions, G. corollarium cultures produced small, slightly oval cysts resembling a previously unidentified cyst type commonly found in sediment trap samples collected from the northern and central open Baltic Sea. Based on LSU rDNA comparison, these cysts were assigned to G. corollarium. The cysts have been observed in many parts of the Baltic Sea, indicating the ecologic versatility of the species and its importance for the Baltic ecosystem. 相似文献
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Fernando Gómez Haruyoshi Takayama David Moreira Purificación López-García 《欧洲藻类学杂志》2016,51(2):226-241
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The classical athecate dinoflagellate genera (Amphidinium, Gymnodinium, Gyrodinium) have long been recognized to be polyphyletic. Amphidinium sensu lato is the most diverse of all marine benthic dinoflagellate genera; however, following the redefinition of this genus ～100 species remain now of uncertain or unknown generic affiliation. In an effort to improve our taxonomic and phylogenetic understanding of one of these species, namely Amphidinium semilunatum, we re‐investigated organisms from several distant sites around the world using light and scanning electron microscopy and molecular phylogenetic methods. Our results enabled us to describe this species within a new heterotrophic genus, Ankistrodinium. Cells of A. semilunatum were strongly laterally flattened, rounded‐quadrangular to oval in lateral view, and possessed a small asymmetrical epicone. The sulcus was wide and characteristically deeply incised on the hypocone running around the antapex and reaching the dorsal side. The straight acrobase with hook‐shaped end started at the sulcal extension and continued onto the epicone. The molecular phylogenetic results clearly showed that A. semilunatum is a distinct taxon and is only distantly related to species within the genus Amphidinium sensu stricto. The nearest sister group to Ankistrodinium could not be reliably determined. 相似文献
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A new species of the dinoflagellate genus Alexandrium, A. tamutum sp. nov., is described based on the results of morphological and phylogenetic studies carried out on strains isolated from two sites in the Mediterranean Sea: the Gulf of Trieste (northern Adriatic Sea) and the Gulf of Naples (central Tyrrhenian Sea). Vegetative cells were examined in LM and SEM, and resting cysts were obtained by crossing strains of opposite mating type. Alexandrium tamutum is a small‐sized species, resembling A. minutum in its small size, the rounded‐elliptical shape and the morphology of its cyst. The main diagnostic character of the new species is a relatively wide and large sixth precingular plate (6″), whereas that of A. minutum is much narrower and smaller. Contrary to A. minutum, A. tamutum strains did not produce paralytic shellfish poisoning toxins. Phylogenies inferred from the nuclear small subunit rDNA and the D1/D2 domains of the large subunit nuclear rDNA of five strains of A. tamutum and numerous strains of other Alexandrium species showed that A. tamutum strains clustered in a well‐supported clade, distinct from A. minutum. 相似文献
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Tae Oh Cho Sung Min Boo Max H. Hommersand Christine A. Maggs Lynne McIvor Suzanne Fredericq 《Journal of phycology》2008,44(3):721-738
On the basis of comparative morphology and phylogenetic analyses of rbcL and LSU rDNA sequence data, a new genus, Gayliella gen. nov., is proposed to accommodate the Ceramium flaccidum complex (C. flaccidum, C. byssoideum, C. gracillimum var. byssoideum, and C. taylorii), C. fimbriatum, and a previously undescribed species from Australia. C. transversale is reinstated and recognized as a distinct species. Through this study, G. flaccida (Kützing) comb. nov., G. transversalis (Collins et Hervey) comb. nov., G. fimbriata (Setchell et N. L. Gardner) comb. nov., G. taylorii comb. nov., G. mazoyerae sp. nov., and G. womersleyi sp. nov. are based on detailed comparative morphology. The species referred to as C. flaccidum and C. dawsonii from Brazil also belong to the new genus. Comparison of Gayliella with Ceramium shows that it differs from the latter by having an alternate branching pattern; three cortical initials per periaxial cell, of which the third is directed basipetally and divides horizontally; and unicellular rhizoids produced from periaxial cells. Our phylogenetic analyses of rbcL and LSU rDNA gene sequence data confirm that Gayliella gen. nov. represents a monophyletic clade distinct from most Ceramium species including the type species, C. virgatum. We also transfer C. recticorticum to the new genus Gayliella. 相似文献
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Diana Sarno Wiebe H. C. F. Kooistra Linda K. Medlin Isabella Percopo Adriana Zingone 《Journal of phycology》2005,41(1):151-176
The morphology of strains of Skeletonema Greville emend Sarno et Zingone was examined in LM, TEM, and SEM and compared with sequence data from nuclear small subunit rDNA and partial large subunit rDNA. Eight distinct entities were identified, of which four were known: S. menzelii Guillard, Carpenter et Reimann; S. pseudocostatum Medlin emend. Zingone et Sarno; S. subsalsum (Cleve) Bethge; and S. tropicum Cleve. The other four species were new: S. dohrnii Sarno et Kooistra sp. nov., S. grethae Zingone et Sarno sp. nov., S. japonicum Zingone et Sarno sp. nov., and S. marinoi Sarno et Zingone sp. nov. Skeletonema species fell into four morphologically distinct groups corresponding to four lineages in the small subunit and large subunit trees. Lineage I included S. pseudocostatum, S. tropicum, S. grethae, and S. japonicum. All have external processes of the fultoportulae with narrow tips that connect with those of sibling cells via fork‐, knot‐, or knuckle‐ like junctions. Lineage II included only the solitary species S. menzelii. Lineage III comprised S. dohrnii and S. marinoi. This latter pair have flattened and flared extremities of the processes of the fultoportulae, which interdigitate with those of contiguous valves without forming knots or knuckles. Lineage IV only contained the brackish water species S. subsalsum. Some species also differ in their distribution and seasonal occurrence. These findings challenge the concept of S. costatum as a single cosmopolitan and opportunistic species and calls for reinterpretation of the vast body of research data based on this species. 相似文献
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TheNor-loci of polyploid wheats and their putative diploid progenitor species were assayed by probing isolated nuclear DNA with ribosomal DNA spacer sequences (spacer rDNA sequences, isolated by cloning), from theNor-loci of genomes B (Triticum aestivum), G (T. timopheevi), B (syn. S,T. speltoides), A (T. monococcum) and V (Dasypyrum villosum). DNA samples for analysis were digested with the restriction endonuclease Taq 1 and assayed by DNA-DNA hybridization under standard (37°C) and high stringency (64°C) conditions. The assay procedure emphasized differences between the divergent spacer sequences of the polyploid species and allowed relative homologies to the respective sequences in diploid species to be established. — The studies indicated thatT. timopheevi andT. speltoides contain different sets of spacer rDNA sequences which were readily distinguishable and, in the case ofT. timopheevi, assigned toNor-loci on different chromosomes. This contrast with the spacer rDNA sequences of the majorNor-loci on chromosomes 1 B and 6 B inT. aestivum, which were difficult to distinguish and were deduced to contain very similar sequences. Among the diploid progenitor species only the spacer rDNA fromT. speltoides shared close homology with polyploid wheat species. OneNor-locus inT. timopheevi (on chromosome 6 G) did not show close homology with any of the rDNA spacer probes available. — The data suggestsT. speltoides was the origin of someNor-loci for both theT. timopheevi andT. turgidum lines of tetraploid wheats. The possibility that the 6GNor-locus inT. timopheevi may have derived from an unknown diploid species by introgressive hybridization is discussed. The spacer rDNA sequence probe fromT. monococcum shared good homology with some accessions ofD. villosum and a line ofT. dicoccoides; the implications of this finding for evolution of present-day wheats are discussed. 相似文献