Linked Life Data

1901093

Source:http://linkedlifedata.com/resource/pubmed/id/1901093

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-4-29
pubmed:databankReference
pubmed:abstractText
The complete small ribosomal subunit RNA (srRNA) sequence was determined for the red alga Porphyra umbilicalis and the basidiomycete Leucosporidium scottii, representing two taxa for which no srRNA sequences were hitherto known. These sequences were aligned with other published complete srRNA sequences of 58 eukaryotes. Evolutionary trees were reconstructed by a matrix optimization method from a dissimilarity matrix based on sections of the alignment that correspond to structurally conservative areas of the molecule that can be aligned unambiguously. The overall topology of the eukaryotic tree thus constructed is as follows: first there is a succession of early diverging branches, leading to a diplomonad, a microsporidian, a euglenoid plus kinetoplastids, an amoeba, and slime molds. Later, a nearly simultaneous radiation seems to occur into a number of taxa comprising the metazoa, the red alga, the sporozoa, the higher fungi, the ciliates, the green plants, plus some other less numerous groups. Because the red alga diverges late in the evolutionary tree, it does not seem to represent a very primitive organism as proposed on the basis of morphological and 5S rRNA sequence data. Asco- and basidiomycetes do not share a common ancestor in our tree as is generally accepted on the basis of conventional criteria. In contrast, when all alignment positions, rather than the more conservative ones, are used to construct the evolutionary tree, higher fungi do form a monophyletic cluster. The hypothesis that higher fungi and red algae might have shared a common origin has been put forward. Although the red alga and fungi seem to diverge at nearly the same time, no such relationship can be detected. The newly determined sequences can be fitted into a secondary structure model for srRNA, which is now relatively well established with the exception of uncertainties in a number of eukaryote-specific expansion areas. A specific structural model featuring a pseudoknot is proposed for one of these areas.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-2844
pubmed:author
pubmed:issnType
Print
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
167-77
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
The evolutionary position of the rhodophyte Porphyra umbilicalis and the basidiomycete Leucosporidium scottii among other eukaryotes as deduced from complete sequences of small ribosomal subunit RNA.
pubmed:affiliation
Departement Biochemie, Universiteit Antwerpen (UIA), Belgium.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't