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Use of a deviant mitochondrial genetic code in yellow-green algae 2

Use of a deviant mitochondrial genetic code in yellow-green algae as a landmark for segregating members within the phylum.

Abstract

Several algae that were previously classified in the phylum Xanthophyta (yellow-green algae) were assigned in 1971 to a new phylum, Eustigmatophyta. It was anticipated that the number of algae reclassified to Eustigmatophyta would increase. However, due to the fact that the morphological characteristics that segregate eustigmatophytes from other closely related algae can be only obtained through laborious electron microscopic techniques, the number of members in this phylum have increased rather slowly. We attempted, therefore, to segregate two closely related groups of algae, eustigmatophytes and yellow-green algae, on the basis of a molecular phylogenetic tree as a means of providing an alternative method of distinguishing these phyla. We analyzed the mitochondrial cytochrome oxidase subunit I (COXI) gene sequences of eight algae classified as xanthophyceans and found that six manifested the expected deviant genetic code where AUA codes for methionine (AUA/Met), but not for isoleucine (AUA/Ile) as in the universal genetic code. The other two, Monodus sp. (CCMP 505) and Ophiocytium majus (CCAP 855/1), which were presumed to be yellow-green algae, and all the examined eustigmatophytes utilized AUA for Ile. In addition, the phylogenetic tree of COXI gene sequences showed that the six yellow-green algae bearing the AUA/Met deviant code composed a tight clade with a bootstrap value of 100%. The phylogenetic tree of the corresponding sequences from Monodus sp. and Ophiocytium majus and the eustigmatophytes also composed a tight cluster, but with a bootstrap value of 92%. These results strongly suggest that two previously classified members of yellow-green algae belong to the phylum Eustigmatophyta. Therefore, examination of the mitochondrial genetic code in algae appears to be a potentially very useful genetic marker for classifying these organisms, especially when it is considered with the results obtained through a molecular phylogenetic tree.
Fri August 13 2010 02:52:07 AM by Power1921 1697 views

Comments - 2

  • Shankar wrote:
    Fri August 13 2010 05:36:37 AM

    @ power 1921

    Its Greek and Latin for me :-)
    But your hard work and sincerity comes thru clearly.

    This club is supposed to be a professional networking site. It may be beneficial to you as well as to others if you interact with us with your complete profile.
    Thanks

    Vote Up! 1 Vote Down! 0

  • Sumukhi wrote:
    Fri August 13 2010 11:37:46 AM

    Hi,

    Sounds interesting!
    The more closely related two organisms, the more similar their gene sequences will be. By statistically comparing the similarities and differences in the DNA sequence between the same gene from various organisms, the pattern of how those organisms are related can be deduced. This pattern is normally drawn out in a tree diagram much like a family tree. The closer two lineages are on a tree, the closer their evolutionary relationship.

    With a lot of bioinformatics softwares around, looks like these work sounds easier than the way it was done before.

    Earlier, am given to understand that many scientists faced difficulties in assigning phylogenetic values between related species and which is why algae phylogenetics sounded very hard..

    Have one question here - Was this work using molecular phylogenetics softwares such as PHYLIP or Quick Tree.. Any idea??

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