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Mutations

Mutations

Mutations

Mutations

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations can be characterized in a number of different ways: whether and how they alter the amino acid sequence of the protein, whether they occur over a small or large area of DNA, and whether they occur in somatic cells or germline cells.
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...

Viral Mutations

Viral Mutations

A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material...

Mutation, Gene Flow, and Genetic Drift

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).

Mutations in Microorganisms

Mutations in Microorganisms

Mutations are heritable changes in an organism’s genome involving alterations in the base sequence of DNA or RNA. These changes can influence cellular processes and phenotypic traits, potentially transforming the unaltered wild type into a mutant form. Such changes, termed forward mutations, are pivotal in shaping the genetic diversity of organisms.RNA viruses exhibit the highest mutation rates due to the absence of robust proofreading mechanisms during genome replication. In contrast,...

Point and Frameshift Mutations

Point and Frameshift Mutations

Point mutations are genetic alterations involving the change of a single nucleotide base pair in DNA. Depending on how the alteration affects protein synthesis, they can lead to various consequences.Point mutations fall into the following types:Silent mutations occur when a nucleotide change does not alter the amino acid sequence due to the redundancy of the genetic code. For instance, changing ACC to ACA still encodes threonine, leaving the protein function unaffected. This occurs because...

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Updated: Feb 5, 2026

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

Published on: June 15, 2011

Two novel mutations in

Cun Xue¹, Jinchi Cai², Haiquan Kang³

¹Medical Technology School, Xuzhou Medical University, Xuzhou 221004, China.

Annals of Translational Medicine

|September 14, 2018

Summary

This summary is machine-generated.

Shigella flexneri in China shows high resistance to fluoroquinolones, with novel mutations found in the parE gene. Continuous surveillance is crucial for controlling infections and understanding quinolone resistance mechanisms.

Keywords:

Jiangsu S. flexneri parE plasmid-mediated quinolone resistance (PMQR)resistance

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Last Updated: Feb 5, 2026

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

Published on: June 15, 2011

Quantification of Colonic Stem Cell Mutations

Quantification of Colonic Stem Cell Mutations

Published on: September 25, 2015

The Lambda Select cII Mutation Detection System

The Lambda Select cII Mutation Detection System

Published on: April 26, 2018

Area of Science:

Microbiology
Genetics
Public Health

Background:

Quinolone resistance in Shigella flexneri is a growing public health concern.
Understanding the genetic mechanisms of resistance is crucial for effective treatment strategies.

Purpose of the Study:

To assess the quinolone resistance capacity of Shigella flexneri isolates.
To investigate the underlying quinolone resistance mechanisms, including mutations in QRDR genes and plasmid-mediated resistance determinants.

Main Methods:

Collected 81 S. flexneri isolates from 12 cities in Jiangsu Province, China.
Performed serotyping, antimicrobial susceptibility testing (disc diffusion), and PCR to identify quinolone resistance-determining region (QRDR) genes and plasmid-mediated quinolone resistance (PMQR) determinants.
Confirmed chromosomal mutations via sequencing and BLAST comparison.

Main Results:

High resistance rates observed: 70.4% to nalidixic acid and 58.0% to ciprofloxacin.
Identified prevalent mutations in gyrA (Ser83Leu) and parC (Ser80Ile), and detected mutations in gyrB (Gln517Arg).
Discovered two novel mutations in parE (Ser458Leu and Gly408Asp); qnrS was present in 7.4% of isolates, and aac(6')-Ib-cr in one isolate.

Conclusions:

This study is the first to report mutations in parE among S. flexneri, including novel variants.
High fluoroquinolone resistance in S. flexneri persists in Jiangsu, China, necessitating ongoing surveillance.
Comprehensive and systematic surveillance is vital for the prevention and control of Shigella infections.