Rate and mode differences between nuclear and mitochondrial small-subunit rRNA genes in mushrooms.
نویسندگان
چکیده
Sequences from homologous regions of the nuclear and mitochondrial small-subunit rRNA genes from 10 members of the mushroom order Boletales were used to construct evolutionary trees and to compare the rates and modes of evolution. Trees constructed independently for each gene by parsimony and tested by bootstrap analysis have identical topologies in all statistically significant branches. Examination of base substitutions revealed that the nuclear gene is biased toward C-T transitions and that the distribution of transversions in the mitochondrial gene is strongly effected by an A-T bias. When only homologous regions of the two genes were compared, base substitutions per nucleotide were roughly 16-fold greater in the mitochondrial gene. The difference in the frequency of length mutations was at least as great but was impossible to estimate accurately because of their absence in the nuclear gene. Maximum likelihood was used to show that base-substitution rates vary dramatically among the branches. A significant part of the rate inconstancy was caused by an accelerated nuclear rate in one branch and a retarded mitochondrial rate in a different branch. A second part of the rate variability involved a consistent inconstancy: short branches exhibit ratios of mitochondrial to nuclear divergences of less than 1, while longer branches had ratios of approximately 4:1-8:1. This pattern suggests a systematic error in the branch length calculation. The error may be related to the simplicity of the divergence estimates, which assumes that all base positions have an equal probability of change.
منابع مشابه
Comparison of Mitochondrial-Related Transcriptional Levels of mitochondrial transcription factor A, Nuclear respiratory factor 1 and cytochrome c oxidase subunit 1 Genes in Single Human Oocytes at Various Stages of the Oocyte Maturation
Background: The aim of the current study was to assess the mRNA levels of two mitochondria-related genes, including nuclear-encoded NRF1 (nuclear respiratory factor 1), mitochondrial transcription factor A (TFAM), and mitochondrial-encoded cytochrome c oxidase subunit 1 (MT-CO1) genes in various stages of the human oocyte maturation. Methods: Oocytes were obtained from nine infertile women wit...
متن کاملGenetic Characterization of Argas persicus From Iran by Sequencing of Mitochondrial Cytochrome Oxidase I (COX1) and 16s rRNA Genes
Background: Argas persicus has a great importance for health and veterinary, it can transmit many infectious agents such as Borrelia anserina (avian spirochetosis) and Aegyptianella pullorum. Distinguishing Argasidae due to close morphological relationship is difficult. OBJECTIVES: In the present study, we performed molecular analyses based on PCR and sequencing of Amplicon derived from 16S rRN...
متن کاملOverexpression of Mitochondrial Genes (Mitochondrial Transcription Factor A and Cytochrome c Oxidase Subunit 1) in Mouse Metaphase II Oocytes following Vitrification via Cryotop
Background: Gamete cryopreservation is an inseparable part of assisted reproductive technology, and vitrification is an effective approach to the cryopreservation of oocytes. The aim of this study was to investigate vitrification effects on the expression levels of mitochondrial transcription factor A (Tfam) and mitochondrial-encoded cytochrome c oxidase subunit 1 (Cox1) in mouse metaphase II o...
متن کاملEvidence for a slowed rate of molecular evolution in the order acipenseriformes.
A test of the hypothesis that the members of the order Acipenseriformes (sturgeons and paddlefishes) possess a slowed rate of molecular evolution was carried out by conducting relative-rate comparisons with representatives of four groups of teleost fishes (Cypriniformes, Elopomorpha, Salmonidae, and Percomorpha) using 21 nuclear or mitochondrial protein loci and the nuclear and mitochondrial sm...
متن کاملCodon bias patterns in photosynthetic genes of halophytic grass Aeluropus littoralis
Codon bias refers to the differences in the frequency of occurrence of synonymous codons in coding DNA. Pattern of codon and optimum codon utilization is significantly different between the lives. This difference is due to the long term function of natural selection and evolution process. Genetics drift, mutation and regulation of gene expression are the main reasons for codon bias. In this stu...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Molecular biology and evolution
دوره 9 5 شماره
صفحات -
تاریخ انتشار 1992