Intracellular selection, conversion bias, and the expected substitution rate of organelle genes

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces. Provided there is exchange among organelles, biparental inheritance further strengthens the role of directional intracellular forces in fixing the mutant throughout a population.

Original languageEnglish (US)
Pages (from-to)939-946
Number of pages8
JournalGenetics
Volume130
Issue number4
StatePublished - 1992

Fingerprint

Selection Bias
Organelles
Genes
Genome
Gene Conversion
Population
Haploidy
Germ Cells

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Cite this

Intracellular selection, conversion bias, and the expected substitution rate of organelle genes. / Walsh, James "Bruce".

In: Genetics, Vol. 130, No. 4, 1992, p. 939-946.

Research output: Contribution to journalArticle

@article{bb798577b9564c4b9df4906970118d1c,
title = "Intracellular selection, conversion bias, and the expected substitution rate of organelle genes",
abstract = "A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces. Provided there is exchange among organelles, biparental inheritance further strengthens the role of directional intracellular forces in fixing the mutant throughout a population.",
author = "Walsh, {James {"}Bruce{"}}",
year = "1992",
language = "English (US)",
volume = "130",
pages = "939--946",
journal = "Genetics",
issn = "0016-6731",
publisher = "Genetics Society of America",
number = "4",

}

TY - JOUR

T1 - Intracellular selection, conversion bias, and the expected substitution rate of organelle genes

AU - Walsh, James "Bruce"

PY - 1992

Y1 - 1992

N2 - A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces. Provided there is exchange among organelles, biparental inheritance further strengthens the role of directional intracellular forces in fixing the mutant throughout a population.

AB - A key step in the substitution of a new organelle mutant throughout a population is the generation of germ-line cells homoplasmic for that mutant. Given that each cell typically contains multiple copies of organelles, each of which in turn contains multiple copies of the organelle genome, processes akin to drift and selection in a population are responsible for producing homoplasmic cells. This paper examines the expected substitution rate of new mutants by obtaining the probability that a new mutant is fixed throughout a cell, allowing for arbitrary rates of genome turnover within an organelle and organelle turnover within the cell, as well as (possibly biased) gene conversion and genetic differences in genome and/or organelle replication rates. Analysis is based on a variation of Moran's model for drift in a haploid population. One interesting result is that if the rate of unbiased conversion is sufficiently strong, it creates enough intracellular drift to overcome even strong differences in the replication rates of wild-type and mutant genomes. Thus, organelles with very high conversion rates are more resistant to intracellular selection based on differences in genome replication and/or degradation rates. It is found that the amount of genetic exchange between organelles within the cell greatly influences the probability of fixation. In the absence of exchange, biased gene conversion and/or differences in genome replication rates do not influence the probability of fixation beyond the initial fixation within a single organelle. With exchange, both these processes influence the probability of fixation throughout the entire cell. Generally speaking, exchange between organelles accentuates the effects of directional intracellular forces. Provided there is exchange among organelles, biparental inheritance further strengthens the role of directional intracellular forces in fixing the mutant throughout a population.

UR - http://www.scopus.com/inward/record.url?scp=0026696160&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0026696160&partnerID=8YFLogxK

M3 - Article

C2 - 1582568

AN - SCOPUS:0026696160

VL - 130

SP - 939

EP - 946

JO - Genetics

JF - Genetics

SN - 0016-6731

IS - 4

ER -