What is horizontal gene transfer (HGT)?

Horizontal gene transfer (HGT), also known as lateral gene transfer, is a fascinating process that challenges the traditional view of inheritance. HGT refers to the movement of genetic material between organisms that are not parent and offspring. This means organisms can acquire genes from unrelated sources, expanding their genetic repertoire beyond what they inherit vertically from their ancestors.

What are the main features of horizontal gene transfer?

• Mechanisms: HGT can occur through various mechanisms like conjugation (direct cell-to-cell contact), transduction (using viruses as vectors), and transformation (uptake of free DNA from the environment).
• Frequency: HGT is more common in bacteria and archaea but can also occur between eukaryotes (organisms with a nucleus) under specific circumstances.
• Impact: HGT can introduce new genes for beneficial traits like antibiotic resistance, novel metabolic pathways, or virulence factors.

Why is horizontal gene transfer important?

• HGT is a major driver of evolution, allowing organisms to rapidly acquire new adaptations and capabilities.
• It contributes significantly to the diversity of genes and functions within microbial communities.
• Understanding HGT is crucial for studying antibiotic resistance and the evolution of pathogens.

What are applications of horizontal gene transfer in practice?

• Understanding Microbial Communities: Studying HGT patterns helps elucidate how different microbes interact and share genes within ecosystems.
• Developing New Therapeutics: Studying genes acquired through HGT can provide insights into novel drug targets for combating infectious diseases.
• Biotechnology Applications: Scientists might utilize HGT mechanisms to introduce desirable genes into organisms for bioremediation or industrial applications (limited applications currently).

Practical example

• Antibiotic resistance is a prime example of HGT's impact. Bacteria can acquire genes for resistance from other bacteria through plasmids (small circular DNA molecules) or transposons (mobile genetic elements). This allows them to survive antibiotic treatments previously effective.

Critical comments

• Detecting HGT events can be challenging because it disrupts the typical evolutionary lineage.
• The long-term consequences of horizontally acquired genes on the recipient organism are not always fully understood.
• Ethical concerns exist regarding the deliberate use of HGT in genetically modified organisms.