Research article summary (published 30 Dec 1994):

Monophyly of the order Rodentia inferred from mitochondrial DNA sequences of the genes for 12S rRNA, 16S rRNA, and tRNA-valine.

Full Abstract

A recent analysis of amino acid sequence data (Graur et al.) suggested that the mammalian order Rodentia is polyphyletic, in contrast to most morphological data, which support rodent monophyly. At issue is whether the hystricognath rodents, such as the guinea pig, represent an independent evolutionary lineage within mammals, separate from the sciurognath rodents. To resolve this problem, we sequenced a region (2,645 bp) of the mitochondrial genome of the guinea pig containing the complete 12S ribosomal RNA, 16S ribosomal RNA, and transfer RNA(VAL) genes for comparison with the available sciurognath and other mammalian sequences. Several methods of analysis and statistical tests of the data all show strong support for rodent monophyly (91%-98% bootstrap probability, or BP). Calibration with the mammalian fossil record suggests a Cretaceous date (107 mya) for the divergence of sciurognaths and hystricognaths. An older date (38 mya) for the controversial Mus-Rattus divergence also is supported by these data. Our neighbor-joining analyses of all available sequence data (25 genes) confirm that some individual genes support rodent polyphyly but that tandem analysis of all data does not. We propose that the conflicting results are due to several compounding factors. The unique biochemical properties of some hystricognath metabolic proteins, largely responsible for generating this controversy, may have a single explanation: a cascade effect resulting from inactivation of the zinc-binding abilities of insulin. After excluding six genes possibly affected by insulin inactivation, analyses of all available sequence data (7,117 nucleotide sites, 3,099 amino acid sites) resulted in strong support for rodent monophyly (94% BP for DNA sequences, 90% for protein sequences), which lends support to the insulin-cascade hypothesis.

Author information

Author/s: Frye, M S (MS); Hedges, S B (SB);

Affiliation: Department of Biology, Pennsylvania State University, University Park 16802.

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Molecular biology and evolution (Mol Biol Evol), published in UNITED STATES. (Language: eng)

Reference: 1995-Jan; vol 12 (issue 1) : pp 168-76

Dates: Created 1995/03/31; Completed 1995/03/31; Revised 2006/11/15;

PMID: 7877492, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: 18 Feb 2009 00:00:00)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals Base Sequence DNA Primers DNA, Mitochondrial - genetics; isolation & purification Fossils Guinea Pigs - genetics Humans Liver - metabolism Mammals - genetics

Mammals - genetics Molecular Sequence Data Phylogeny RNA, Ribosomal - genetics RNA, Ribosomal, 16S - genetics RNA, Transfer, Val - genetics Rats Rodentia - classification; genetics Vertebrates - genetics

Associated Chemicals: DNA Primers (0) ; DNA, Mitochondrial (0) ; RNA, Ribosomal (0) ; RNA, Ribosomal, 16S (0) ; RNA, Transfer, Val (0) ; RNA, ribosomal, 12S (0)

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