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1.
Elife ; 82019 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-31149898

RESUMO

The role and extent of horizontal gene transfer (HGT) in eukaryotes are hotly disputed topics that impact our understanding of the origin of metabolic processes and the role of organelles in cellular evolution. We addressed this issue by analyzing 10 novel Cyanidiales genomes and determined that 1% of their gene inventory is HGT-derived. Numerous HGT candidates share a close phylogenetic relationship with prokaryotes that live in similar habitats as the Cyanidiales and encode functions related to polyextremophily. HGT candidates differ from native genes in GC-content, number of splice sites, and gene expression. HGT candidates are more prone to loss, which may explain the absence of a eukaryotic pan-genome. Therefore, the lack of a pan-genome and cumulative effects fail to provide substantive arguments against our hypothesis of recurring HGT followed by differential loss in eukaryotes. The maintenance of 1% HGTs, even under selection for genome reduction, underlines the importance of non-endosymbiosis related foreign gene acquisition.


Assuntos
Adaptação Biológica , Evolução Molecular , Transferência Genética Horizontal , Rodófitas/genética , Proteínas de Algas/genética , DNA de Algas/genética
2.
J Microbiol Biotechnol ; 29(6): 952-961, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31154744

RESUMO

Chlorella spp. are green algae that are found across wide-ranging habitats from deserts to arctic regions, with various strains having adapted to survive under diverse environmental conditions. In this study, two novel Chlorella strains (ABC-002, ABC-008) were isolated from a freshwater lake in South Korea during the winter season and examined for possible use in the biofuel production process. The comparison of ABC-002 and ABC-008 strains with Chlorella vulgaris UTEX265 under two different temperatures (10°C, 25°C) revealed their cold-tolerant phenotypes as well as high biomass yields. The maximum quantum yields of UTEX25, ABC- 002, and ABC-008 at 10°C were 0.5594, 0.6747, and 0.7150, respectively, providing evidence of the relatively higher cold-resistance capabilities of these two strains. Furthermore, both the biomass yields and lipid content of the two novel strains were found to be higher than those of UTEX265; the overall lipid productivities of ABC-002 and ABC-008 were 1.7 ~ 2.8 fold and 1.6 ~ 4.2 fold higher compared to that of UTEX265, respectively. Thus, the high biomass and lipid productivity over a wide range of temperatures indicate that C. vulgaris ABC-002 and ABC-008 are promising candidates for applications in biofuel productions via outdoor biomass cultivation.


Assuntos
Aclimatação/fisiologia , Biocombustíveis , Chlorella vulgaris/classificação , Chlorella vulgaris/fisiologia , Temperatura Baixa , Metabolismo dos Lipídeos , Microbiologia da Água , Biomassa , DNA de Algas/genética , Ácidos Graxos/química , Lipídeos/biossíntese , Lipídeos/química , Filogenia , RNA Ribossômico 18S/genética , República da Coreia , Especificidade da Espécie
3.
PLoS One ; 14(1): e0210986, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30677063

RESUMO

Recent molecular data has strongly suggested that field-collected cysts of snow algae that are morphologically identifiable as the zygotes of Chloromonas nivalis are composed of multiple species. Motile vegetative cells, however, have not been directly obtained from these cysts because of the difficulties involved in inducing their germination. Recently, our comparative molecular analyses, using both field-collected and cultured materials, demonstrated that one Japanese lineage of "C. nivalis zygotes" belongs to C. miwae. Herein, we examined another Japanese lineage of field-collected "C. nivalis zygotes" and a new strain originating from Japan. Our molecular data demonstrated that these two different life cycle stages are conspecific, and that they represent a new species that we herein describe as C. muramotoi sp. nov., based on the vegetative and asexual morphological characteristics of the strain. Multigene phylogenetic analyses showed that this new species was sister to C. miwae. Scanning electron microscopy demonstrated that the cysts of C. muramotoi are different from those of C. miwae, based on the arrangement of the flanges developing on the cell wall.


Assuntos
Clorofíceas/classificação , Clorofíceas/genética , Clorofíceas/ultraestrutura , DNA de Algas/genética , Japão , Microscopia Eletrônica de Transmissão , Filogenia , Análise de Sequência de DNA , Neve , Especificidade da Espécie , Zigoto/ultraestrutura
4.
Biosci Rep ; 39(1)2019 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-30530569

RESUMO

Chlamydomonas reinhardtii, the unicellular green algae, is the model organism for studies in various physiological processes and for bioindustrial applications. To explore the molecular mechanisms underlying physiological processes or to establish engineered cell lines, the exogenous DNA needs to be integrated into the genome for the insertional mutagenesis or transgene expression. However, the amount of selected marker DNA is not seriously considered in the existing electroporation methods for mutants library construction. Here, we reported a rapid-and-high-efficiency transformation technique for cell-walled strains using square-wave electroporation system. The final yield with this electroporation method was 2-6 × 103 transformants per µg exogenous DNA for cell-walled strains in a strain-dependent manner. In general, this electroporation technique was the easy and applicable way to build a mutant library for screening phenotypes of interest.


Assuntos
Chlamydomonas reinhardtii/genética , DNA de Algas/genética , Eletroporação/métodos , Mutagênese Insercional/métodos , Transformação Genética , Chlamydomonas reinhardtii/metabolismo , Clonagem Molecular , DNA de Algas/química , DNA de Algas/metabolismo , Eletroporação/instrumentação , Marcadores Genéticos , Mutagênese Insercional/instrumentação , Plasmídeos/química , Plasmídeos/metabolismo , Transgenes
5.
Microbiome ; 6(1): 225, 2018 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-30558682

RESUMO

BACKGROUND: Utricularia are rootless aquatic carnivorous plants which have recently attracted the attention of researchers due to the peculiarities of their miniaturized genomes. Here, we focus on a novel aspect of Utricularia ecophysiology-the interactions with and within the complex communities of microorganisms colonizing their traps and external surfaces. RESULTS: Bacteria, fungi, algae, and protozoa inhabit the miniature ecosystem of the Utricularia trap lumen and are involved in the regeneration of nutrients from complex organic matter. By combining molecular methods, microscopy, and other approaches to assess the trap-associated microbial community structure, diversity, function, as well as the nutrient turn-over potential of bacterivory, we gained insight into the nutrient acquisition strategies of the Utricularia hosts. CONCLUSIONS: We conclude that Utricularia traps can, in terms of their ecophysiological function, be compared to microbial cultivators or farms, which center around complex microbial consortia acting synergistically to convert complex organic matter, often of algal origin, into a source of utilizable nutrients for the plants.


Assuntos
Bactérias/classificação , Fungos/classificação , Lamiales/microbiologia , Metagenômica/métodos , Organismos Aquáticos/microbiologia , Organismos Aquáticos/fisiologia , Bactérias/genética , Bactérias/isolamento & purificação , DNA de Algas/genética , DNA Bacteriano/genética , DNA Fúngico/genética , Fungos/genética , Fungos/isolamento & purificação , Perfilação da Expressão Gênica/métodos , Lamiales/fisiologia , Consórcios Microbianos , Filogenia
6.
Protist ; 169(6): 803-825, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30448592

RESUMO

The diatom genus Orthoseira Thwaites (Bacillariophyta) is a ubiquitous taxon in aerial diatom assemblages, with species found globally. Cylindrical cell shape and radial symmetry of this genus has led to its historical placement in the Coscinodiscophyceae ('radial centric' diatoms), but its systematic relationships have remained uncertain. We present a five-gene phylogeny, based on nuclear (nSSU rDNA) and chloroplast (rbcL, psbC, psbA, and psaB) genes to determine the phylogenetic placement of Orthoseira among the diatoms. The concatenated multi-gene phylogenies and nSSU-only gene tree demonstrate that Orthoseira is deeply embedded within a clade of the Mediophyceae ('multipolar centric' diatoms). Throughout all phylogenetic analyses, Orthoseira was shown to be sister to the genera Terpsinoë and Hydrosera. Through comparison of topologies reflecting competing hypotheses about the placement of Orthoseira, it was determined that the hypothesis that Orthoseira, represented here by O. dendroteres and O. roeseana, is a member of the Melosirales should be rejected. Therefore, lack of morphological similarity between Hydrosera, Orthoseira, and Terpsinoë is hypothesized to be the result of changes in habitat preferences that lead to an ancient divergence event between the Orthoseirales and the Hydrosera, Terpsinoë clade.


Assuntos
Diatomáceas/classificação , Diatomáceas/genética , Filogenia , Proteínas de Cloroplastos/genética , Análise por Conglomerados , DNA de Algas/química , DNA de Algas/genética , DNA de Cloroplastos/química , DNA de Cloroplastos/genética , DNA Ribossômico/química , DNA Ribossômico/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
7.
Sci Rep ; 8(1): 17189, 2018 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-30464297

RESUMO

Mesodinium spp. are commonly found in marine and brackish waters, and several species are known to contain red, green, or both plastids that originate from cryptophyte prey. We observed the seasonal succession of Mesodinium spp. in a Japanese brackish lake, and we analysed the origin and diversity of the various coloured plastids within the cells of Mesodinium spp. using a newly developed primer set that specifically targets the cryptophyte nuclear 18S rRNA gene. Mesodinium rubrum isolated from the lake contained only red plastids originating from cryptophyte Teleaulax amphioxeia. We identified novel Mesodinium sp. that contained only green plastids or both red and green plastids originating from cryptophytes Hemiselmis sp. and Teleaulax acuta. Although the morphology of the newly identified Mesodinium sp. was indistinguishable from that of M. rubrum under normal light microscopy, phylogenetic analysis placed this species between the M. rubrum/major species complex and a well-supported lineage of M. chamaeleon and M. coatsi. Close associations were observed in cryptophyte species composition within cells of Mesodinium spp. and in ambient water samples. The appearance of suitable cryptophyte prey is probably a trigger for succession of Mesodinium spp., and the subsequent abundance of Mesodinium spp. appears to be influenced by water temperature and dissolved inorganic nutrients.


Assuntos
Cilióforos/crescimento & desenvolvimento , Cilióforos/parasitologia , Criptófitas/classificação , Criptófitas/crescimento & desenvolvimento , Cilióforos/classificação , Cilióforos/genética , Análise por Conglomerados , Criptófitas/genética , DNA de Algas/química , DNA de Algas/genética , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Japão , Lagos/parasitologia , Filogenia , RNA Ribossômico 18S/genética , Estações do Ano , Análise de Sequência de DNA
8.
Antonie Van Leeuwenhoek ; 111(12): 2425-2440, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30069722

RESUMO

The Carpathian Basin is a lowland plain located mainly in Hungary. Due to the nature of the bedrock, alluvial deposits, and a bowl shape, many lakes and ponds of the area are characterized by high alkalinity. In this study, we characterized temporal changes in eukaryal and bacterial community dynamics with high throughput sequencing and relate the changes to environmental conditions in Lake Velence located in Fejér county, Hungary. The sampled Lake Velence microbial populations (algal and bacterial) were analyzed to identify potential correlations with other community members and environmental parameters at six timepoints over 6 weeks in the Spring of 2012. Correlations between community members suggest a positive relationship between certain algal and bacterial populations (e.g. Chlamydomondaceae with Actinobacteria and Acidobacteria), while other correlations allude to changes in these relationships over time. During the study, high nitrogen availability may have favored non-nitrogen fixing cyanobacteria, such as the toxin-producing Microcystis aeruginosa, and the eutrophic effect may have been exacerbated by high phosphorus availability as well as the high calcium and magnesium content of the Carpathian Basin bedrock, potentially fostering exopolymer production and cell aggregation. Cyanobacterial bloom formation could have a negative environmental impact on other community members and potentially affect overall water quality as well as recreational activities. To our knowledge, this is the first prediction for relationships between photoautotrophic eukaryotes and bacteria from an alkaline, Hungarian lake.


Assuntos
Cianobactérias/genética , Eutrofização , Lagos/microbiologia , Consórcios Microbianos/genética , Feófitas/genética , Filogenia , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/isolamento & purificação , Acidobacteria/metabolismo , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Actinobacteria/metabolismo , Álcalis/química , Cálcio/química , Cálcio/metabolismo , Clorofíceas/classificação , Clorofíceas/genética , Clorofíceas/metabolismo , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , Cianobactérias/metabolismo , DNA de Algas/genética , DNA Bacteriano/genética , Hungria , Concentração de Íons de Hidrogênio , Magnésio/química , Magnésio/metabolismo , Microcystis/classificação , Microcystis/genética , Microcystis/isolamento & purificação , Microcystis/metabolismo , Nitrogênio/química , Nitrogênio/metabolismo , Feófitas/classificação , Feófitas/isolamento & purificação , Feófitas/metabolismo , Fósforo/química , Fósforo/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Microbiologia da Água
9.
Gene ; 678: 100-104, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30092340

RESUMO

Aided by a host of bioinformatics tools, primary and secondary structural analyses of the internal transcribed spacer 2 (ITS2) from the eukaryotic ribosomal RNA repeat have a long and enviable record of service to diversity studies of fungi, plants and protists. Automation of annotation, secondary structure estimation and sequence alignment have become routine for the vast majority of ITS2 sequences. Challenges to the bioinformatics pipeline for ITS2 analysis generally arise in cases where the sequence length lies well outside the norm. These sequences generally defy protocols for annotation and secondary structure prediction. The long ITS2 sequences (ca. 600 nucleotides) from the green alga, Jenufa, offered an opportunity to explore this problem. Custom BLAST parameters revealed the presence of 4-helix structures (200-250 nucleotides) embedded in the 5' portion of several long ITS2 sequences of Jenufa. Of special note is the ITS2 sequence of J. lobulosa where a 4-helix structure was obtained for both the embedded ITS2 and for the complete sequence. Phylogenetic analysis of these typically-sized sequences resolved Golenkinia longispicula as the sister to Jenufa. Our observations indicate that other long ITS2 sequences should be examined for evidence of expansion or duplication. In addition, if the embedded ITS2 sequences are functional, then ribogenesis is almost certainly more diverse than is already apparent from studies of humans and yeast.


Assuntos
Clorófitas/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , DNA de Algas/química , DNA de Algas/genética , Conformação de Ácido Nucleico , Filogenia , Alinhamento de Sequência
10.
Genome Biol Evol ; 10(9): 2248-2254, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-30102347

RESUMO

Plastid genomes are not normally celebrated for being large. But researchers are steadily uncovering algal lineages with big and, in rare cases, enormous plastid DNAs (ptDNAs), such as volvocine green algae. Plastome sequencing of five different volvocine species has revealed some of the largest, most repeat-dense plastomes on record, including that of Volvox carteri (∼525 kb). Volvocine algae have also been used as models for testing leading hypotheses on organelle genome evolution (e.g., the mutational hazard hypothesis), and it has been suggested that ptDNA inflation within this group might be a consequence of low mutation rates and/or the transition from a unicellular to multicellular existence. Here, we further our understanding of plastome size variation in the volvocine line by examining the ptDNA sequences of the colonial species Yamagishiella unicocca and Eudorina sp. NIES-3984 and the multicellular Volvox africanus, which are phylogenetically situated between species with known ptDNA sizes. Although V. africanus is closely related and similar in multicellular organization to V. carteri, its ptDNA was much less inflated than that of V. carteri. Synonymous- and noncoding-site nucleotide substitution rate analyses of these two Volvox ptDNAs suggest that there are drastically different plastid mutation rates operating in the coding versus intergenic regions, supporting the idea that error-prone DNA repair in repeat-rich intergenic spacers is contributing to genome expansion. Our results reinforce the idea that the volvocine line harbors extremes in plastome size but ultimately shed doubt on some of the previously proposed hypotheses for ptDNA inflation within the lineage.


Assuntos
DNA de Algas/genética , Genomas de Plastídeos , Volvox/genética , Clorófitas/genética , Evolução Molecular , Plastídeos/genética , Análise de Sequência de DNA
11.
Gene ; 673: 225-238, 2018 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-29933020

RESUMO

The complete mitochondrial genome is greatly important for studies on genetic structure and phylogenetic relationship at various taxonomic levels. To obtain information about the evolutionary trends of mtDNA in the Ulvophyceae and also to gain insights into the phylogenetic relationships between ulvophytes and other chlorophytes, we determined the mtDNA sequence of Caulerpa lentillifera (sea grape) using de novo mitochondrial genome sequencing. The complete genomic DNA of C. lentillifera was circular and 209,034 bp in length, and it was the largest green-algal mitochondrial genome sequenced to date, with a low gene density of 65.2%, which is reminiscent of the "expanded" pattern of evolution exhibited by embryophyte mtDNAs. The C. lentillifera mtDNA consisted of a typical set of 17 protein-coding genes (PCGs), 20 transfer RNA (tRNA) genes, three ribosomal RNA (rRNA) genes, 42 putative open reading frames (ORFs) and 29 introns, which had homologs in green-algal mtDNAs displaying an "ancestral" or a "reduced-derived" pattern of evolution. The overall base composition of its mitochondrial genome was 24.19% for A, 24.94% for T, 25.80% for G, 25.07% for C and 50.87% for GC. The mitochondrial genome of C. lentillifera was characterized by numerous small intergenic regions and introns, which was clearly different from other green algae. With the exception of the NADH dehydrogenase subunit 6 (ND6), ND1, ATP and three tRNA genes (tRNA-His, tRNA-Thr and tRNA-Ala), all other mitochondrial genes were encoded on the heavy strand. All of the PCGs had ATG as their start codon and employed TAA, TGA or TAG as their termination codon. To gain insights into the evolutionary trends of mtDNA in the Ulvophyceae, we inferred the complete mtDNA sequence of C. lentillifera, an ulvophyte belonging to a distinct, early-diverging lineage. Taken together, our data offered useful information for the studies on phylogenetic hypotheses and phylogenetic relationships of C. lentillifera within the Chlorophyta.


Assuntos
Caulerpa/genética , DNA Mitocondrial/genética , Genoma Mitocondrial , DNA de Algas/genética , Evolução Molecular , Biblioteca Gênica , Genoma , Íntrons , Conformação de Ácido Nucleico , Fases de Leitura Aberta , Filogenia , RNA Ribossômico/genética , RNA de Transferência/genética
12.
Mycopathologia ; 183(5): 853-858, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29872935

RESUMO

Protothecosis is a rare disease caused by environmental algae of the genus Prototheca. These are saprophytic, non-photosynthetic, aerobic, colorless algae that belong to the Chlorellaceae family. Seven different species have been described. Prototheca zopfii genotype 2 and P. wickerhamii are most commonly involved in pathogenic infections in humans and animals. The objective of this work is to describe, for the first time, a case of protothecosis caused by P. zopfii genotype 1 in a dog. The dog, a 4-year-old mix bred male, was presented to a veterinary clinic in Montevideo, Uruguay, with multiple skin nodules, one of which was excised by surgical biopsy. The sample was examined histologically and processed by PCR, DNA sequencing, and restriction fragments length polymorphisms for the detection and genotyping of P. zopfii. In addition, transmission electron microscopy and scanning electron microscopy were performed. Histology showed severe ulcerative granulomatous dermatitis and panniculitis with myriads of pleomorphic algae. Algal cells were 4-17 µm in size, with an amphophilic, 2-4-µm-thick wall frequently surrounded by a clear halo, contained flocculant material and a deeply basophilic nucleus, and internal septae with daughter cells (endospores) consistent with endosporulation. Ultrastructurally, algal cells/endospores at different stages of development were found within parasitophorous vacuoles in macrophages. Prototheca zopfii genotype 1 was identified by molecular testing, confirming the etiologic diagnosis of protothecosis.


Assuntos
Doenças do Cão/diagnóstico , Doenças do Cão/patologia , Prototheca/isolamento & purificação , Animais , Biópsia , DNA de Algas/química , DNA de Algas/genética , Doenças do Cão/microbiologia , Cães , Genótipo , Histocitoquímica , /microbiologia , Masculino , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Prototheca/classificação , Prototheca/genética , Análise de Sequência de DNA , Pele/patologia , Uruguai
13.
Int J Syst Evol Microbiol ; 68(3): 851-859, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29458669

RESUMO

With the advent of molecular phylogenetic methods, it has become possible to assess the bioversity of snow algae more accurately. In this study, we focused on a morphological, ultrastructural and taxonomic description of a new Chloromonas-like alga isolated from snow in the High Arctic (Svalbard). Light and transmission electron microscopy revealed broad ellipsoidal or ellipsoidal-cylindrical, occasionally spherical cells with a chloroplast without a pyrenoid, an inconspicuous eyespot and a papilla. The size difference and the aforementioned morphological traits clearly distinguished the alga from its closest counterparts within the genus Chloromonas. Moreover, we were able to cultivate the alga at both 5 and 20 °C, revealing the psychrotolerant nature of the strain. Phylogenetic analyses of the plastid rbcL and nuclear 18S rRNA gene showed that the alga is nested within a clade containing a number of psychrotolerant strains within the Chloromonadinia phylogroup (Chlorophyceae). In the rbcL phylogeny, the alga formed an independent lineage, sister to the freshwater species Chloromonas paraserbinowii. Comparisons of secondary structure models of a highly variable ITS2 rDNA marker showed support for a distinct species identity for the new strain. The ITS2 secondary structure of the new isolate differed from the closest matches 'Chlamydomonas' gerloffii and Choloromonas reticulata by three and five compensatory base changes, respectively. Considering the morphological and molecular differences from its closest relatives, a new psychrotolerant species from the Arctic, Choromonas arctica sp. nov., is proposed.


Assuntos
Filogenia , Neve , Volvocida/classificação , DNA de Algas/genética , DNA Espaçador Ribossômico/genética , Plastídeos/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA , Svalbard , Volvocida/genética
14.
Plant Cell ; 30(2): 429-446, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29367304

RESUMO

The cyclin-dependent kinase CDK1 is essential for mitosis in fungi and animals. Plant genomes contain the CDK1 ortholog CDKA and a plant kingdom-specific relative, CDKB. The green alga Chlamydomonas reinhardtii has a long G1 growth period followed by rapid cycles of DNA replication and cell division. We show that null alleles of CDKA extend the growth period prior to the first division cycle and modestly extend the subsequent division cycles, but do not prevent cell division, indicating at most a minor role for the CDK1 ortholog in mitosis in Chlamydomonas. A null allele of cyclin A has a similar though less extreme phenotype. In contrast, both CDKB and cyclin B are essential for mitosis. CDK kinase activity measurements imply that the predominant in vivo complexes are probably cyclin A-CDKA and cyclin B-CDKB. We propose a negative feedback loop: CDKA activates cyclin B-CDKB. Cyclin B-CDKB in turn promotes mitotic entry and inactivates cyclin A-CDKA. Cyclin A-CDKA and cyclin B-CDKB may redundantly promote DNA replication. We show that the anaphase-promoting complex is required for inactivation of both CDKA and CDKB and is essential for anaphase. These results are consistent with findings in Arabidopsis thaliana and may delineate the core of plant kingdom cell cycle control that, compared with the well-studied yeast and animal systems, exhibits deep conservation in some respects and striking divergence in others.


Assuntos
Proteínas de Algas/metabolismo , Ciclo Celular/genética , Chlamydomonas reinhardtii/genética , Quinases Ciclina-Dependentes/metabolismo , Replicação do DNA , DNA de Algas/genética , Mitose/genética , Proteínas de Algas/genética , Chlamydomonas reinhardtii/enzimologia , Chlamydomonas reinhardtii/fisiologia , Ciclina B/genética , Ciclina B/metabolismo , Quinases Ciclina-Dependentes/genética
15.
Gene ; 640: 14-20, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29017964

RESUMO

The genetic basis of stress resistance in extremophilic microalgae is not well studied. In this study, a gene of unknown function, the cluster58 or CL58 gene, was identified from the halotolerant green alga Chlamydomonas W80 and characterized. The CL58 gene encodes a protein containing a domain of unknown function, the CHRD domain, and a putative secretory signaling sequence at its N-terminus. The levels of CL58 mRNA increased in response to high copper levels and low temperatures. When the CL58 gene was heterologously expressed as a fusion gene with the NanoLuc luciferase gene in Chlamydomonas reinhardtii, a majority of the NanoLuc activity was detected in the culture medium compared with that in the intracellular fraction. A mutagenic analysis revealed that the putative secretory signaling sequence was sufficient for the secretion of the CL58-NanoLuc fusion protein. In addition, we expressed the protein encoded by the CL58 gene in Escherichia coli; the recombinant, soluble protein was then purified. In summary, we identified a novel gene from C. W80 that appears to encode a stress-responsive, CHRD domain-containing secreted protein.


Assuntos
Chlamydomonas reinhardtii/genética , DNA de Algas/genética , Glicoproteínas/química , Peptídeos e Proteínas de Sinalização Intercelular/química , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Transgenes/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Chlamydomonas reinhardtii/metabolismo , Temperatura Baixa , Cobre/toxicidade , Proteínas de Plantas/metabolismo , Domínios Proteicos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência
16.
J Eukaryot Microbiol ; 65(3): 382-391, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29080384

RESUMO

The Parachlorella clade was put forward as a group within the family Chlorellaceae in 2004. Recent molecular analyses have revealed that Dictyosphaerium morphotype algae form several independent lineages within the Parachlorella clade, and new genera and species have been established. In this study, we focus on the diversity of Dictyosphaerium morphotype algae within the Parachlorella clade, based on 42 strains from China. We used combined analyses of morphology and molecular data based on SSU and internal transcribed spacer region (ITS) rDNA sequences to characterize these algae. In addition, the secondary structure of ITS2 was compared to delineate new lineages. Our results revealed high phylogenic diversity of Dictyosphaerium morphotype algae, and we describe five distinct lineages. We examined the morphological features of these five lineages, and morphological differences are difficult to find compared with other Dictyosphaerium morphotype algae. The five distinct lineages were not described as new genera currently. We lastly discuss the taxonomic problems regarding the Dictyosphaerium morphotype within the Parachlorella clade, and possible solutions are considered.


Assuntos
Clorófitas/classificação , Clorófitas/genética , DNA de Algas/genética , DNA Intergênico/genética , China , Cloroplastos/fisiologia , Filogenia
17.
Microbiol Res ; 206: 74-81, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29146262

RESUMO

Marine disease ecology is a growing field of research, particularly for host organisms negatively impacted by a changing climate and anthropogenic activities. A decrease in health and increase in susceptibility to disease has been hypothesised as the mechanism behind wide-spread seagrass die-offs related to wasting disease in the past. However, seagrass wasting disease and the causative pathogen, Labyrinthula, have been vastly understudied in the southern hemisphere. Our aim was to build on the current knowledge of Australian Labyrinthula descriptions and phylogeny, while also providing a first look at wasting disease ecology in Australia. Five seagrass species along a 750km stretch of coastline in southeastern Australia were sampled. The resulting 38 Labyrinthula isolates represented a diversity of morphotypes and five haplotypes of varying phylogenetic clade positions and virulence. The haplotypes clustered with previously-described phylogenetic clades containing isolates from Asia, USA and Europe. Pathogenicity tests confirmed, for the first time, the presence of at least two pathogenic haplotypes in Australia. While historically there have been no reports of wasting disease-related seagrass habitat loss, the presence of pathogenic Labyrinthula highlights the need for disease monitoring and research to understand seagrass wasting disease ecology in Australia.


Assuntos
Doenças das Plantas/parasitologia , Estramenópilas/classificação , Estramenópilas/patogenicidade , Austrália , Técnicas de Cultura de Células , DNA de Algas/genética , Ecologia , Ecossistema , Haplótipos , Interações Hospedeiro-Parasita , Biologia Marinha , Parasitologia , Filogenia , Filogeografia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA , Estramenópilas/genética , Estramenópilas/isolamento & purificação , Virulência
18.
Curr Biol ; 27(24): 3771-3782.e6, 2017 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-29199074

RESUMO

Virtually all plastid (chloroplast) genomes are circular double-stranded DNA molecules, typically between 100 and 200 kb in size and encoding circa 80-250 genes. Exceptions to this universal plastid genome architecture are very few and include the dinoflagellates, where genes are located on DNA minicircles. Here we report on the highly deviant chloroplast genome of Cladophorales green algae, which is entirely fragmented into hairpin chromosomes. Short- and long-read high-throughput sequencing of DNA and RNA demonstrated that the chloroplast genes of Boodlea composita are encoded on 1- to 7-kb DNA contigs with an exceptionally high GC content, each containing a long inverted repeat with one or two protein-coding genes and conserved non-coding regions putatively involved in replication and/or expression. We propose that these contigs correspond to linear single-stranded DNA molecules that fold onto themselves to form hairpin chromosomes. The Boodlea chloroplast genes are highly divergent from their corresponding orthologs, and display an alternative genetic code. The origin of this highly deviant chloroplast genome most likely occurred before the emergence of the Cladophorales, and coincided with an elevated transfer of chloroplast genes to the nucleus. A chloroplast genome that is composed only of linear DNA molecules is unprecedented among eukaryotes, and highlights unexpected variation in plastid genome architecture.


Assuntos
Clorófitas/genética , Cromossomos de Plantas/genética , Genoma de Cloroplastos/genética , Genoma de Planta/genética , DNA de Algas/genética
19.
J Phycol ; 53(6): 1193-1205, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28865145

RESUMO

The resting cysts of the benthic dinoflagellate Prorocentrum leve from a natural reservoir in Gujan-Mestras (Gironde, France) were described in this study. The incubated urn-shaped cysts gave rise to cells of P. leve. Morphological observations through light microscopy and scanning electron microscopy, particularly of the periflagellar platelets, combined with large subunit ribosomal DNA sequences obtained through single-cell analysis confirm their affinity to the species P. leve. The cysts were characterized by a specific shape and the presence of an anterior plug. This is the first conclusive evidence for fossilizable resting stages within the Prorocentrales, one of the major orders within the Dinophyceae. Palynological treatments show that the cysts and endospores withstand hydrochloric and hydrofluoric acids. Micro-Fourier transform infrared analysis on single specimens suggests that the composition of the endospore is cellulosic and the cyst wall a more robust, noncellulosic ß-glucan. The spectra overall are similar to other published spectra of resting cysts from autotrophic, planktonic dinoflagellates.


Assuntos
DNA de Algas/genética , DNA Ribossômico/genética , Dinoflagelados/genética , Dinoflagelados/isolamento & purificação , França , Lagos , Filogenia , Análise de Sequência de DNA
20.
Sci Rep ; 7(1): 11679, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28916791

RESUMO

The evolution of sex chromosomes and mating loci in organisms with UV systems of sex/mating type determination in haploid phases via genes on UV chromosomes is not well understood. We report the structure of the mating type (MT) locus and its evolutionary history in the green seaweed Ulva partita, which is a multicellular organism with an isomorphic haploid-diploid life cycle and mating type determination in the haploid phase. Comprehensive comparison of a total of 12.0 and 16.6 Gb of genomic next-generation sequencing data for mt- and mt+ strains identified highly rearranged MT loci of 1.0 and 1.5 Mb in size and containing 46 and 67 genes, respectively, including 23 gametologs. Molecular evolutionary analyses suggested that the MT loci diverged over a prolonged period in the individual mating types after their establishment in an ancestor. A gene encoding an RWP-RK domain-containing protein was found in the mt- MT locus but was not an ortholog of the chlorophycean mating type determination gene MID. Taken together, our results suggest that the genomic structure and its evolutionary history in the U. partita MT locus are similar to those on other UV chromosomes and that the MT locus genes are quite different from those of Chlorophyceae.


Assuntos
Evolução Molecular , Ordem dos Genes , Loci Gênicos , Genômica , Alga Marinha/genética , Ulva/genética , Cromossomos , Biologia Computacional , DNA de Algas/genética , Sequenciamento de Nucleotídeos em Larga Escala
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