Another Unicellular Genome


Check it out:



Green algae, like plants, have cells walls composed of cellulose. Chitin, on the other hand, is used in fungal cell walls and the exoskeleton of arthropods. Consider (from the same link above):

Finally, the analysis revealed surprising observations with respect to genes involved in cell wall metabolism. The Chlorella cell wall contains glucosamine polymers, such as chitin and chitosan, instead of cellulose and hemicelluloses that make up the cell walls of land plants. The genomic analysis indeed revealed no homologs of Arabidopsis genes involved in synthesis of cellulose or hemicelluloses. However, homologs were found to chitin metabolism genes present in Chlorella DNA viruses, leading to the remarkable hypothesis that components of Chlorella chitin metabolism could have been acquired via lateral gene transfer from viruses. If this is indeed the case, large DNA viruses predominantly associated with microalgae and marine protists might have played a larger role in the evolution of their hosts than previously recognized.

So chitin has been independently employed among algae, fungi, and arthropods. And a global network of viruses may have facilitated the emergence of these evolutionary “innovations.”

2 responses to “Another Unicellular Genome

  1. Is this the same Chlorella that rapidly becomes a multicellular organism in the presence of predators? (Boraas 1983)

  2. Valery Anisimov

    According to my investigation key genes responsible for photosynthesis also can be delivered by the viruses. It can also easily explain strange representation of the photosynthetic bacterias taxons on the evolutionary tree. In fact I guess that initially ability to stimulate photosynthesis in the host cell may be used by viruses just as a method to extract additional energy for self replication.

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