Physiologische und biochemische Beiträge zur Taxonomie der GattungChlorella

Hellmann, Volker; Kessler, Erich

doi:10.1007/bf02451772

Cited by 37 publications

(3 citation statements)

References 21 publications

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“…Two examples illustrate the degree of heterogeneity. (a) The G+C contents of the nuclear DNAs of Chlorella species range from 43% to 79% (67). However, most isolates assigned to the same species have similar G+C contents.…”

Section: (A) Viruses That Infect Chlorella Isolate Nc64a (Nc64a Virmentioning

confidence: 99%

Unusual Life Style of Giant Chlorella Viruses

2003

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Paramecium bursaria chlorella virus (PBCV-1) is the prototype of a family of large, icosahedral, plaque-forming, dsDNA viruses that replicate in certain unicellular, eukaryotic chlorella-like green algae. Its 330-kb genome contains ~373 protein-encoding genes and 11 tRNA genes. The predicted gene products of ~50% of these genes resemble proteins of known function, including many that are unexpected for a virus, e.g., ornithine decarboxylase, hyaluronan synthase, GDP-D-mannose 4,6 dehydratase, and a potassium ion channel protein. In addition to their large genome size, the chlorella viruses have other features that distinguish them from most viruses. These features include: (a) The viruses encode multiple DNA methyltransferases and DNA site-specific endonucleases. (b) The viruses encode at least some, if not all, of the enzymes required to glycosylate their proteins. (c) PBCV-1 has at least three types of introns, a self-splicing intron in a transcription factorlike gene, a spliceosomal processed intron in its DNA polymerase gene, and a small intron in one of its tRNA genes. (d) Many chlorella virus-encoded proteins are either the smallest or among the smallest proteins of their class. (e) Accumulating evidence indicates that the chlorella viruses have a very long evolutionary history.

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Section: (A) Viruses That Infect Chlorella Isolate Nc64a (Nc64a Virmentioning

confidence: 99%

Unusual Life Style of Giant Chlorella Viruses

2003

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“…However, algae assigned to the genus Chlorella are more heterogeneous than their simple morphology suggests. This degree of heterogeneity is illustrated with two examples: (a) The nuclear DNAs of algae assigned to the genus have G+C contents ranging from 43% to 79% (49). However, most isolates that have been assigned to the same species contain similar G+C contents.…”

Section: Chlorella Virusesmentioning

confidence: 99%

Giant Viruses Infecting Algae

Etten

Meints

1999

Annu. Rev. Microbiol.

206

187

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Paramecium bursaria chlorella virus (PBCV-1) is the prototype of a family of large, icosahedral, plaque-forming, double-stranded-DNA-containing viruses that replicate in certain unicellular, eukaryotic chlorella-like green algae. DNA sequence analysis of its 330, 742-bp genome leads to the prediction that this phycodnavirus has 376 protein-encoding genes and 10 transfer RNA genes. The predicted gene products of approximately 40% of these genes resemble proteins of known function. The chlorella viruses have other features that distinguish them from most viruses, in addition to their large genome size. These features include the following: (a) The viruses encode multiple DNA methyltransferases and DNA site-specific endonucleases; (b) PBCV-1 encodes at least part, if not the entire machinery to glycosylate its proteins; (c) PBCV-1 has at least two types of introns--a self-splicing intron in a transcription factor-like gene and a splicesomal processed type of intron in its DNA polymerase gene. Unlike the chlorella viruses, large double-stranded-DNA-containing viruses that infect marine, filamentous brown algae have a circular genome and a lysogenic phase in their life cycle.

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“…The GC content of the DNAs from different species ranges from 43 to 79% (7). Hybridization of DNAs from different species of Chlorella to one another indicate that there are several distinctively different groups of species within this genus (10).…”

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confidence: 99%

Isolation and Characterization of Chloroplast DNA from Chlorella ellipsoidea

Yamada¹

1982

Plant Physiol.

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A circular DNA molecule was isolated from chloroplasts of Chorella eHlipsoidea. The DNA had a buoyant density of 1.695 grams per cubic centimeter (36% GC) and a contour length of 56 micrometers (175 kilobase pairs). The restriction endonuclease analysis gave the same size. Agarose gel electrophoretic patterns of chloroplast DNA digested by several restriction endonucleases were also presented. The digestion by the restriction enzymes, Hpall, Mspl, SmaI, and XmaI revealed no appreciable methylation at CG sites in chloroplast DNA.The green alga represented by the genus Chlorella includes species that differ considerably in biochemical and physiological characteristics (11). The GC content of the DNAs from different species ranges from 43 to 79% (7). Hybridization of DNAs from different species of Chlorella to one another indicate that there are several distinctively different groups of species within this genus (10). In contrast, studies on cp DNAs' from different strains of Chlorella by means of thermal denaturation and renaturation kinetics showed that this genome was quite homogeneous within this genus (2) and similar to those of other algae such as Chlamydomonas and Euglena (1). Recently, the cp DNAs of Chiamydomonas reinhardii (14, 15) and of Euglena gracilis bacillaris (5) have been characterized. Both cp DNAs were physically mapped with restriction endonucleases and some specific genes (e.g. rRNAs, etc.) were located on these maps. The cp DNA of Chlamydomonas was also shown to be methylated during certain stages of the life cycle of this alga (16). The cp DNAs of these two algae are physically organized quite differently. This raises the question as to the organization of other algal cp DNAs such as those from the genus Chlorella.Recently, Yamada and Sakaguchi (25) induced protoplast formation in Chlorella species and discussed the possibility of isolating intact chloroplasts and cp DNA from the protoplasts. The present study includes the isolation of an intact circular cp DNA of C. ellipsoidea C-87, the measurement of its buoyant density (GC content) and contour length (mol wt), and some restriction endonuclease fragment patterns. This is the first report of the intact isolation of cp DNA from Chlorella. reciprocal shaker with a 16 h light (3,000 lux) and 8 h dark cycle for 4 to 5 d.Preparation of Protoplasts and Chloroplasts. Protoplasts were prepared as previously described from freshly harvested cells (25). For the isolation of chloroplasts, the prepared protoplasts were washed and resuspended in the homogenization medium A (13) with a modification (0.3 M mannitol was replaced by 0.3 M sorbitol). The protoplast suspension (109 cells ml-1) was homogenized at 0°C by a glass homogenizer with a motor-driven Teflon pestle. The homogenate was centrifuged at 1,000 rpm for 5 min to remove unbroken cells and autospores. The supernatant (about 5 ml) was then layered onto a discontinuous density gradient containing 1.0, 1.5, 2.0, and 2.5 M sucrose (17). The gradients were centrifuged at 4°C in an RPS 25 ro...

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Physiologische und biochemische Beiträge zur Taxonomie der GattungChlorella

Cited by 37 publications

References 21 publications

Unusual Life Style of Giant Chlorella Viruses

Unusual Life Style of Giant Chlorella Viruses

Giant Viruses Infecting Algae

Isolation and Characterization of Chloroplast DNA from Chlorella ellipsoidea

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