Price et al. [(1999). J. Bacteriol. 181:2358–2362] conducted a genetic study of the toxin transport protein (PA) of Bacillus anthracis, the bacterium that causes anthrax in humans. Within the 2294-nucleotide gene in 26 strains they identified five point mutations—two missense and three synonyms—among different isolates. Necropsy samples from an anthrax outbreak in 1979 revealed a novel missense mutation and five unique nucleotide changes among ten victims. The authors concluded that these data indicate little or no horizontal transfer between different B. anthracis strains.

What is meant by 'horizontal transfer'?

Key Concepts

Horizontal Gene Transfer

Horizontal gene transfer (HGT) refers to the process by which an organism incorporates genetic material from another organism without being its offspring. This mechanism allows for the exchange of genes between different species, contributing to genetic diversity and the evolution of traits such as antibiotic resistance. In bacteria, HGT can occur through transformation, transduction, or conjugation, significantly impacting their adaptability and survival.

Point Mutations

Point mutations are changes in a single nucleotide base pair in the DNA sequence of a gene. These mutations can be classified as missense mutations, which result in a different amino acid being incorporated into a protein, or synonymous mutations, which do not change the amino acid sequence. Understanding point mutations is crucial for studying genetic variation and the functional consequences of genetic changes in organisms.

Bacillus anthracis and Anthrax

Bacillus anthracis is a bacterium that causes anthrax, a serious infectious disease. It can form spores that survive in harsh conditions, making it a potent pathogen. The study of its genetic variations, such as those identified in the toxin transport protein, helps researchers understand the epidemiology of anthrax and the genetic factors that contribute to its virulence and transmission among hosts.