1,721,002 research outputs found
Choricystis and Lewiniosphaera gen. nov. (Trebouxiophyceae Chlorophyta), two different green algal endosymbionts in freshwater sponges
No full textAssociations of freshwater sponges with coccoid green algae have been known for a long time. Two types of coccoid green algae, which are commonly assigned as zoochlorellae, are recognized by morphology: small coccoids (< 3 μ[my]m) without pyrenoids and larger Chlorella-like algae (4-6 μ[my]m) with pyrenoids. Despite their wide distribution in some freshwater sponges, these green algae were never studied using a combined analysis of morphology and molecular phylogeny. We investigated several endosymbiotic strains isolated from different Spongilla species, which were available in culture collections. Phylogenetic analyses of SSU and ITS rDNA sequences revealed that the strain SAG 211-40a is a member of the Chlorellaceae and represents a new species of the newly erected genus Lewiniosphaera, L symbiontica. The phylogenetic position was confirmed by morphology and ITS-2 barcode. The endosymbionts without pyrenoid were identified as Choricystis parasitica by morphology and phylogenetic analyses. The comparison with free-living strains revealed the recognition of two new Choricystis species, C. krienitzii and C. limnetica, which were confirmed by molecular signatures in V9 region of SSU rDNA and ITS-2 barcode.Version of recor
The green puzzle Stichococcus (Trebouxiophyceae, Chlorophyta): New generic and species concept among this widely distributed genus
No full textThe genus Jaagichlorella Reisigl (Trebouxiophyceae, Chlorophyta) and its close relatives: an evolutionary puzzle
No full textThe genus Chlorella (in its traditional sense) is polyphyletic and belongs to at least twelve independent lineages of the Trebouxiophyceae and Chlorophyceae. Most of the aquatic species belong to the Chlorella and Parachlorella clades (within the so-called Chlorella-lineage of the Trebouxiophyceae), or to the genera Scenedesmus and Mychonastes (within the DO-group of the Chlorophyceae) according to phylogenetic analyses of the SSU and ITS rDNA sequences. In contrast to the aquatic species, the terrestrial strains investigated so far form a monophyletic lineage (Watanabea-clade) within the Trebouxia-lineage of the Trebouxiophyceae. Several genera with Chlorella-like morphology (Chloroidium, Heterochlorella, Watanabea, Kalinella, Viridiella and others) belong to the Watanabea clade. We studied 22 strains isolated from soil, bark, and artificial hard substrates, which have been traditionally identified as Chlorella luteoviridis or as unidentified Chlorella. To clarify the taxonomical status and intrageneric diversity of this group, we used an integrated approach (molecular phylogeny of SSU and ITS rDNA sequences, secondary structures, DNA barcoding, and morphology) including the ecological distribution. All investigated strains showed a low phenotypic plasticity, but a high genetic diversity, which could be only resolved in complex phylogenetic analyses based on the secondary structures of the investigated genes. Considering these results, we reestablished the genus Jaagichlorella for Heterochlorella and Heveochlorella, and proposed new combinations (J. luteoviridis, J. hainangensis, J. roystonensis, and J. sphaerica) as well as the new species, J. africana
Reevaluation and discovery of new species of the rare genus Watanabea and establishment of Massjukichlorella gen. nov. (Trebouxiophyceae, Chlorophyta) using an integrative approach
No full textSolotvynia, a New Coccoid Lineage among the Ulvophyceae (Chlorophyta)
No full textCoccoid Ulvophyceae are often overlooked despite their wide distribution. They occur as epiphytes on marine seaweeds or grow on stones or on shells of mussels and corals. Most of the species are not easy to identify based solely on morphology. However, they form two groups based on the flagellated cells during asexual reproduction. The biflagellated coccoids are monophyletic and represent the genus Sykidion (Sykidiales). In contrast, the quadriflagellated taxa are polyphyletic and belong to different genera and orders. The newly investigated strains NIES-1838 and NIES-1839, originally identified as Halochlorococcum, belong to the genus Chlorocystis (C. john-westii) among the order Chlorocystidales. The unidentified strain CCMP 1293 had almost an identical SSU and ITS-2 sequence to Symbiochlorum hainanense (Ignatiales) but showed morphological differences (single chloroplast, quadriflagellated zoospores) compared with the original description of this species (multiple chloroplasts, aplanospores). Surprisingly, the strain SAG 2662 (= ULVO-129), together with the published sequence of MBIC 10461, formed a new monophyletic lineage among the Ulvophyceae, which is highly supported in all of the bootstrap and Bayesian analyses and approximately unbiased tests of user-defined trees. This strain is characterized by a spherical morphology and also form quadriflagellated zoospores, have a unique ITS-2 barcode, and can tolerate a high variation of salinities. Considering our results, we emend the diagnosis of Symbiochlorum and propose the new genus Solotvynia among the new order Solotvyniales
The polyphasic approach revealed new species of Chloroidium (Trebouxiophyceae, Chlorophyta)
No full textChlorella-like coccoid green algae are widely distributed in many types of habitats such as freshwater, terrestrial and marine. One group of terrestrial microalgae belonging to the Trebouxiophyceae forms the monophyletic lineage of the Watanabea clade. This clade exclusively comprises of ellipsoid and spherical coccoid green algae, which traditionally have been assigned as different species of Chlorella. Within this clade, seven out of ten genera are described mainly based on phylogenetic analyses of SSU and rbcL sequences. Most of the genera are represented by only one or two species that are rarely found in natural samples. In contrast, the genus Chloroidium is widely distributed across different habitats. We investigated 34 new isolates, which were originally assigned as Chloroidium or Chlorella, using an integrative approach. The phylogenetic analyses of SSU and ITS rDNA sequences revealed nine lineages, eight of which were highly supported in all of our bootstrap and Bayesian analyses. The ITS-2/CBC approach clearly demonstrated that these nine lineages represent individual species. The haplotype network analyses revealed that three out of them were widely distributed and showed no preference for any habitat. The comprehensive study of SSU and rbcL datasets also revealed that no clear synapomorphy could be found to support the assigned genus Parachloroidium. As a result of our findings, we proposed that both species belonging to Parachloroidium be transferred to Chloroidium. In addition, we re-established two species originally described by Chodat as new members of Chloroidium (C. lichenum, C. viscosum). Two of the nine lineages (C. antarcticum, C. arboriculum) were newly described in this study
Prasiolopsis wulf-kochii (Prasiolales, Trebouxiophyceae), a New Species Occurring in Hairs of the Sloth Bradypus tridactylus
No full textThe monotypic genus Prasiolopsis has been known for a long time, but is often overlooked because of difficulties in identification and the morphological variability between uniseriate filaments and cell packages forming pseudoparenchymatic thalli depending on age. We investigated a strain (SAG 84.81) originally denoted as Trichophilus welckeri, which was isolated from the hairs of the sloth Bradypus tridactylus, and compared it with other available strains of Prasiolopsis and of the sister genus Pseudomarvania. Our investigations clearly showed that this strain differed in morphology, especially of the chloroplast, from those originally described for Trichophilus. Phylogenetic analyses of the SSU and ITS rDNA sequences revealed that the strain SAG 84.81 is sister to several strains of P. ramosa within the Prasiola clade (Trebouxiophyceae). Using the ITS-2/CBC approach, we clearly demonstrated that this strain represented a new species of Prasiolopsis, which we proposed here as P. wulf-kochii. In addition, we evaluated the ITS-2/CBC approach by comparing it with the two species of Pseudomarvania. All investigated strains showed CBCs and HCBCs, which support their species delimitation. The sequencing data of Trichophilus welckeri available in GenBank were phylogenetically re-evaluated by including all representatives of the Ulotrichales (Ulvophyceae). Our analyses showed that these sequences formed their own lineage within this order
Toward a monograph of non-marine Ulvophyceae using an integrative approach (Molecular phylogeny and systematics of terrestrial Ulvophyceae II.)
No full textPhylogenetic analyses of SSU rDNA sequences have shown that coccoid and filamentous green algae are distributed among all classes of the Chlorophyta. One of these classes, the Ulvophyceae, mostly contains marine seaweeds and microalgae. However, new studies have shown that there are filamentous and sarcinoid freshwater and terrestrial species (including symbionts in lichens) among the Ulvophyceae, but very little is known about these species. Ultrastructural studies of some of them have confirmed that the flagellar apparatus of zoospores (counterclockwise basal body orientation) is typical for the Ulvophyceae. In addition to ultrastructural features, the presence of a “Codiolum”-stage is characteristic of some members of this algal class. We studied more than 50 strains of freshwater and terrestrial ulvophycean microalgae obtained from the different public culture collection and our own isolates using an integrative approach. Three independent lineages of the Ulvophyceae containing terrestrial species were revealed by these methods. Unexpectedly each of these lineages contained several isolates that morphologically developed a high degree of phenotypic plasticity, and included hidden phylogenetic diversity that let us to the description of several new genera and species.</jats:p
A new mesophilic isolate of Pleurastrosarcina , a genus previously only reported from arid habitats
No full textEuropean Union’s Horizon 2020Austrian Science Fun
Chlamydomonas schloesseri sp. nov. (Chlamydophyceae, Chlorophyta) revealed by morphology, autolysin cross experiments, and multiple gene analyses
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