中国眼裸藻属(Euglenaria)分类学研究

为对眼裸藻属Euglenaria Karnkowska, Linton&Kwiatowski进行分类学修订,研究以采自中国的12株3种眼裸藻属物种为材料,基于形态学和分子生物学手段对眼裸藻属进行系统发育研究,鉴定了3种眼裸藻属物种,分别是尾眼裸藻Euglenaria caudata (Hubner) Karnkowska et Linton、项圈眼裸藻Euglenaria anabaena(Mainx) Karnkowska et Linton和棒形眼裸藻Euglenaria clavata (Skuja) Karnkowska et Linton,提供了它们的形态特征及分子数据。基于最大似然法和贝叶斯法构建了系统发育树,以亲缘关系较近的双鞭藻科Eutreptiaceae Hollande物种为外类群,其余的裸藻类分为扁裸藻科Phacaceae Kim, Triemer&Shin和裸藻科Euglenaceae Dujardin物种两大支,眼裸藻属位于裸藻科分支(0.84/-),共包含28株眼裸藻属物种,主要分为3个小分支,每个小支的支持率均高达99%以上,项圈眼裸藻和尾...     

PHYLOGENETIC AND TAXONOMIC POSITION OF LEPOCINCLIS FUSCA COMB. NOV. (=EUGLENA FUSCA) (EUGLENACEAE): MORPHOLOGICAL AND MOLECULAR JUSTIFICATION1

We studied the morphological diversity and analyzed the small subunit rDNA sequences of two taxa formerly known as Euglena spirogyra Ehr. and Euglena fusca (Klebs) Lemmermann. Our studies confirmed that the two should have the rank of a species, namely Lepocinclis spirogyroides (Ehr.) Marin et Melkonian and Lepocinclis fusca (Klebs) Kosmala et Zakry? comb. nov. (Euglenophyceae). We are defining new diagnostic features for these species, namely the size and the shape of the cells and the shape of the papillae, as well as designating epitypes for them.     

PHYLOGENETIC ANALYSIS OF THE GENUS EUGLENA (EUGLENOPHYCEAE) WITH PARTICULAR REFERENCE TO THE TYPE SPECIES EUGLENA VIRIDIS1

Euglena viridis (subgenus Euglena) serves as the type species for the genus Euglena. In this study, molecular phylogenetic analyses using a small subunit (SSU) and a combined SSU–partial large subunit rDNA data set for members of the genus Euglena showed that strains identified as E. viridis on the basis of morphology are distributed between two separate nonsister clades. Although all the E. viridis strains examined were morphologically indistinguishable and possessed spherical mucocysts and stellate chloroplasts with one paramylon center, there was a high degree of sequence divergence between the E. viridis strains in different clades, making this a cryptic species. Like E. viridis, all taxa from the subgenus Euglena are characterized by having one or more stellate chloroplasts with paramylon grains clustered around the center of the chloroplast. These additional taxa were divided into four clades in all the molecular analyses. Strains of Euglena stellata formed two nonsister clades whose members had a single aggregate chloroplast with paramylon center and spindle‐shaped mucocysts. A geniculata clade included species with one or two stellate chloroplasts with paramylon centers and spherical mucocysts, and the cantabrica clade had members with one stellate chloroplast with paramylon center and spherical mucocysts often arranged in spiral rows. Interspersed among these were three additional clades bearing taxa from the subgenus Calliglena that contains members with discoid plastids and pyrenoids that may or may not be capped with paramylon. These taxa formed a laciniata clade, mutabilis clade, and gracilis clade. This study demonstrates that E. viridis and E. stellata are cryptic species that can only be distinguished at the molecular level. Because E. viridis is the designated type species for the genus Euglena, we designated an epitype for E. viridis.     

PHYLOGENY AND SYSTEMATICS OF EUGLENA (EUGLENACEAE) SPECIES WITH AXIAL,STELLATE CHLOROPLASTS BASED ON MORPHOLOGICAL AND MOLECULAR DATA—NEW TAXA,EMENDED DIAGNOSES,AND EPITYPIFICATIONS1

Morphological and molecular studies, as well as original literature reexamination, necessitate establishment of five Euglena species with a single axial, stellate chloroplast [Euglena viridis (O. F. Müller) Ehrenberg 1830 , Euglena pseudoviridis  Chadefaud 1937 , Euglena stellata  Mainx 1926 , Euglena pseudostellata sp. nov., and Euglena cantabrica  Pringsheim 1956 ], three species with two chloroplasts (Euglena geniculata Dujardin ex Schmitz 1884 , Euglena chadefaudii  Bourrelly 1951 , and Euglena pseudochadefaudii sp. nov.), and one species with three chloroplasts (Euglena tristella  Chu 1946 ). The primary morphological features, allowing distinction of the considered species are the presence and the shape of mucocysts, as well as the number of chloroplasts. Spherical mucocysts occur in E. cantabrica and E. geniculata, while spindle‐shaped mucocysts are present in E. stellata, E. pseudostellata, E. chadefaudii, E. pseudochadefaudii, and E. tristella. No mucocysts are observed in E. viridis and E. pseudoviridis. Two new species (E. pseudochadefaudii sp. nov. and E. pseudostellata sp. nov.) differ from the respective species, E. chadefaudii and E. stellata, only at the molecular level. Molecular signatures and characteristic sequences are designated for nine distinguished species. Emended diagnoses for all and delimitation of epitypes for seven species (except E. viridis and E. tristella) are proposed.     

THE SPECIES EUGLENA DESES (EUGLENACEAE) REVISITED: NEW MORPHOLOGICAL AND MOLECULAR DATA1

For this study, we have examined the literature and the morphological diversity, as well as analyzed the nuclear SSU rDNA sequences of two very common and cosmopolitan species formerly known as Euglena deses Ehrenb. and Euglena intermedia (G. A. Klebs) F. Schmitz. Our studies have shown that there is evidence for distinguishing only one species (E. deses). Here, we define new diagnostic features for E. deses, namely, periplast ornamentation (the presence of small papillae—discovered for the first time in this species) and the lateral location of the anterior canal opening, from which the flagellum emerges. We also designate the epitype and emend the diagnosis for E. deses.     

Chloroplast Genome Evolution in the Euglenaceae

Over the last few years multiple studies have been published outlining chloroplast genomes that represent many of the photosynthetic euglenid genera. However, these genomes were scattered throughout the euglenophyceaean phylogenetic tree, and focused on comparisons with Euglena gracilis. Here, we present a study exclusively on taxa within the Euglenaceae. Six new chloroplast genomes were characterized, those of Cryptoglena skujai, E. gracilis var. bacillaris, Euglena viridis, Euglenaria anabaena, Monomorphina parapyrum, and Trachelomonas volvocina, and added to six previously published chloroplast genomes to determine if trends existed within the family. With this study: at least one genome has now been characterized for each genus, the genomes of different strains from two taxa were characterized to explore intraspecific variability, and a second taxon has been characterized for the genus Monomorphina to examine intrageneric variability. Overall results showed a large amount of variability among the genomes, though a few trends could be identified both within Euglenaceae and within Euglenophyta. In addition, the intraspecific analysis indicated that the similarity of a genome sequence between strains was taxon dependent, and the intrageneric analysis indicated that the majority of the evolutionary changes within the Euglenaceae occurred intergenerically.     

PLASTID MORPHOLOGY,ULTRASTRUCTURE, AND DEVELOPMENT IN COLACIUM AND THE LORICATE EUGLENOPHYTES (EUGLENOPHYCEAE)1

Chloroplast morphology was investigated in five species of euglenophytes: Trachelomonas volvocinopsis Swirenko, Strombomonas verrucosa (Daday) Deflandre, Strombomonas costata Deflandre, Colacium mucronatum Bourrelly et Chafaud, and Colacium vesiculosum Ehrenberg. All five species share a common plastid morphotype: disk‐shaped plastids with a pyrenoid that protrudes asymmetrically toward the center of the cell and is capped by a single large grain of paramylon that conforms to the shape of the pyrenoid. Although plastids demonstrated some degree of diversity among the species studied, it was not consistent with current generic boundaries. The plastids of S. verrucosa show a developmental pattern similar to that of Euglena gracilis. The plastids divide during the early portion of the light phase after cell division, and pyrenoids are reduced or absent in dividing plastids. Developmental patterns of plastid replication also suggest that these five taxa share recent common ancestry with members of the genus Euglena subgenus Calliglena.     

TAXONOMIC REVISIONS OF MORPHOLOGICALLY SIMILAR SPECIES FROM TWO EUGLENOID GENERA: EUGLENA (E. GRANULATA AND E. VELATA) AND EUGLENARIA (EU. ANABAENA,EU. CAUDATA,AND EU. CLAVATA)1

The establishment of epitypes (together with the emended diagnoses) for three species of Euglenaria Karnkowska, E. W. Linton et Kwiatowski [Eu. anabaena (Mainx) Karnkowska et E. W. Linton; Eu. caudata (Hübner) Karnkowska et E. W. Linton; and Eu. clavata (Skuja) Karnkowska et E. W. Linton] and two species of Euglena Ehrenberg [E. granulata (Klebs) Schmitz and E. velata Klebs] was achieved due to literature studies, verification of morphological diagnostic features (cell size, cell shape, number of chloroplasts, the presence of mucocysts), as well as molecular characters (SSU rDNA). Now all these species are easy to identify and distinguish, despite their high morphological similarity, that is, spindle‐shaped (or cylindrically spindle‐shaped) cells and parietal, lobed chloroplasts with a single pyrenoid, accompanied by bilateral paramylon caps located on both sides of the chloroplast. E. granulata is the only species in this group that has spherical mucocysts. E. velata is distinguished by the largest cells (90–150 μm) and has the highest number of chloroplasts (>30). Eu. anabaena has the fewest chloroplasts (usually 3–6), and its cells are always (whether the organism is swimming or not) spindle‐shaped or cylindrically spindle‐shaped, in contrast to the cells of Eu. clavata, which are club‐shaped (clavate) while swimming and only after stopping change to resemble the shape of a spindle or a cylindrical spindle; Eu. clavata has numerous chloroplasts (15–20). Eu. caudata is characterized by asymmetrical spindle‐shaped (fusiform) cells, that is, with an elongated rear section and a shorter front section; the number of chloroplasts normally ranges from 7 to 15.     

The effect of rapamycin on biodiesel-producing protist Euglena gracilis

Rapamycin induces autophagy with lipid remodeling in yeast and mammalian cells. To investigate the lipid biosynthesis of Euglena gracilis, rapamycin was supplemented in comparison with two model algae, Chlamydomonas reinhardtii and Cyanidioschyzon merolae. In Euglena, rapamycin induced the reduction of chlorophylls and the accumulation of neutral lipids without deterring its cell proliferation. Its lipidomic profile revealed that the fatty acid composition did not alter by supplementing rapamycin. In Chlamydomonas, however, rapamycin induced serious growth inhibition as reported elsewhere. With a lower concentration of rapamycin, the alga accumulated neutral lipids without reducing chlorophylls. In Cyanidioschyzon, rapamycin did not increase neutral lipids but reduced its chlorophyll content. We also tested fatty acid elongase inhibitors such as pyroxasulfone or flufenacet in Euglena with no significant change in its neutral lipid contents. In summary, controlled supplementation of rapamycin can increase the yield of neutral lipids while the scheme is not always applicable for other algal species.     

Extensive structural conservation exists among several homologs of two Euglena chloroplast group II introns

82 of the 155 chloroplast introns in Euglena gracilis have been categorized as group II introns. Because they are shorter and more divergent than group II introns from other organisms, the assignment of these Euglena introns to the group II class has been questioned. In the current study, two homologs of E. gracilispetB intron 1 and four homologs of psbC intron 2 have been isolated from related species and characterized. Based on a comparative sequence analysis of intron homologs, the intron core and four of the six helical domains present in the canonical group II intron structural model are conserved in E. gracilispetB intron 1 and psbC intron 2 and all of their homologs. Distal portions of domain I, which are involved in most of the tertiary interactions, are less well conserved than the central core. Received: 27 June 1997 / Accepted: 6 August 1997     

<Emphasis Type="Italic">Elliptochloris bilobata</Emphasis> var. <Emphasis Type="Italic">corticola</Emphasis> var. nov. (Trebouxiophyceae,Chlorophyta), a novel subaerial coccal green alga

We investigated a previously unidentified subaerial corticolous strain of the genus Elliptochloris Tschermak-Woess. The alga shares the generic morphological characters with Elliptochloris bilobata, the type species of the genus, but it has a thicker cell wall of adult globular cells, different chloroplast structure and it also differs in shape of elliptical autospores. The differences of the autospore shape between both species were evaluated using landmark-based geometric morphometrics. The 18S rDNA gene sequence of the new alga forms a monophyletic clade with the authentic strain of E. bilobata within the green algal class Trebouxiophyceae close to representatives of the genus Coccomyxa. We describe the new alga as Elliptochloris bilobata var. corticola var. nov. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

DEVELOPMENT OF MUCILAGINOUS SURFACES IN EUGLENOIDS. II. FLAGELLATED,CREEPING AND PALMELLOID CELLS OF EUGLENA1

Critical-point dried (CPD) cells from clonal cultures of Euglena gracilis Klebs (Z strain), E. deses Ehrb., E. tripteris (Duj.) Klebs and E. myxocylindracea Bold & MacEntee were examined by scanning electron microscopy. Flagellated motile cells of E. gracilis are naked except for a few strands of mucilage on the posterior tip. Flagellated cells of E. tripteris have a permanent mucilage coating often of uneven distribution and usually not as well developed as that of nonflagellated creeping cells which have a distinctive mucilage. In E. deses the coating appears rough due to the aggregation of isolated groups of strands above the cell surface. In E. tripteris the coating appears smooth except for breaks near the articulation of the pellicular strips where the mucilage may rise above the surface to form waves. At high magnification this mucilage consists of a network of strands generally lying parallel to the cell surface; the strands become obscure in some specimens. In E. myxocylindracea elongated, mucilage-coated cells contract to form spheres which undergo further mucilage deposition producing the mucilage covering of palmellae. As palmellae mature, the mucilage surface becomes less porous and the individuality of most mucilage strands is lost.     

The Molecular Biology of Euglena gracilis. VIII. Glycitols and Monosaccharides

Mannitol is identified as the major component of the small molecule pool of Euglena gracilis strain Z. Smaller amounts of glycerol also are found. Results of tracer studies and enzymic measurements indicate that both major mannitol pathways found in bacteria are present in Euglena.     

ROLE OF GOLGI APPARATUS IN MUCILAGE PRODUCTION AND CYST FORMATION IN EUGLENA GRACILIS (EUGLENOPHYCEAE)1

Dark grown cells of Euglena gracilis Klebs (strain Z Pringsheim) encyst when placed in minus nitrogen media for 48–72 h in the dark. The number of cisternae per dictyosome decreases from 10–20 to 6–12 during encystment. Cisternae dilate and fill with mucilage within 12–18 h after induction. The material is secreted into the reservoir and deposited onto the cell surface. The encysting cells rotate as they develop resulting in the deposition of a thick mucilaginous layer over the cell surface. The secretion product has been identified as polysaccharide with the periodic acid-silver methenamine reaction. Mucilage has not been observed in the endoplasmic reticulum adjacent to the pellicle. The product present in the dictyosornes and on the cell surface react identically to the silver reagent.     

Cytological Characterization of a Giant Strain of Euglena gracilis Obtained from Dark-starved Cultures

Euglena gracilis green cells were dark-starved for four months. After this period almost the entire population died, while a few giant, viable cells appeared in the culture. The giantism was maintained after repeated subcultures in growth medium in light or dark conditions. However, the phenomenon was not permanent, and the morphological characteristics of the wild-type Euglena were gradually restored. In giant cells nuclei enlarged greatly, DNA content increased and the Golgi apparatus greatly proliferated. Chloroplasts and mitochondria increased in number and size and often presented structural modifications when compared with normal Euglena. Importantly, in the giant cells that were maintained in darkness in resting or growth conditions chloroplasts persisted as structured organelles which appeared red-fluorescent under UV illumination. Whether giantism is a phenotypic or a genotypic change is still debated. In our case, the evolution of this phenomenon, chiefly the enhanced DNA content, suggests that teratism is a multiploid mutation with the possibility of a return to the normoploid condition. Constitutive chloroplasts are present in most algae, except for a few species, among which is Euglena gracilis. The persistence of differentiated plastids in darkness in giant Euglena is considered to be a return to an ancestral condition and may, therefore, be phylogenetically important.     

TWO DIFFERENT SPECIES OF EUGLENA,E. GENICULATA AND E. MYXOCYLINDRACEA (EUGLENOPHYCEAE), ARE VIRTUALLY GENETICALLY AND MORPHOLOGICALLY IDENTICAL1

We investigated the similarity of a single Euglena myxocylindracea strain, isolated originally by Bold and MacEntee, to several Euglena geniculata strains on both morphological and DNA levels. We found the three DNA stretches, consisting of fragments coding for the parts of cytoplasmic and chloroplast small subunit rRNA, and the internal transcribed spacer (ITS2) of cytoplasmic rDNA, with the combined length of 4332 nucleotides, are identical in E. myxocylindracea and E. geniculata, strain SAG 1224‐4b. Morphological differences between E. myxocylindracea and any E. geniculata strain examined were well within the range of E. geniculata variability as well. The only difference behind the distinction of E. myxocylindracea from E. geniculata is the presence of the second chloroplast in the latter. However, we were able to induce the appearance of the second chloroplast in the cells of E. myxocylindracea and its disappearance in the cells of E. geniculata by changing the composition of the culture media. We therefore conclude that E. myxocylindracea Bold and MacEntee should be regarded as an environmental form of E. geniculata Dujardin. For the first time the morphology of E. geniculata chloroplasts was shown as revealed by confocal laser microscopy.     

Analisi ultrastrutturale degli effetti della monensina in Euglena gracilis,con particolare riguardo all'apparato di Golgi

Abstract

Ultrastructural analysis of the effects of monensin in Euglena gracilis, with special reference to the Golgi apparatus. - The monovalent ionophore, monensin, is known to affect the mature (trans) half of the dictyosomes of several organisms, including Euglena gracilis. We demonstrated that the exposure to high concentrations of this compound (2.5 × 10^?5 to 10^?4M) provoked remarkable swelling also in the forming (cis) half of Euglena cisternae. Additional dilations affected the thylakoids of both mature chloroplasts and proplastids of greening cells in which the organelle development was slower than in the control group. No osmotic swelling was observed for the mitochondria. Since monnesin exchanges one proton for each monovalent cation (Na⁺ or K⁺) transported, it follows that an energy driven influx of H⁺ is necessary to accumulate sufficient osmotically active ions in a membrane compartment. Thus it is possible that H⁺-ATPases are present on both forming and mature half of Euglena dictyosomes.