What are microsatellites?

Microsatellites, also known as simple sequence repeats (SSRs) or short tandem repeats (STRs), are fascinating stretches of DNA composed of short, repetitive sequences. Despite their simplicity, they hold significant value in various biological studies.

What are the main features of microsatellites?

• Repetitive Nature: Microsatellites consist of short nucleotide motifs (2-6 base pairs) repeated in tandem arrays, varying in length between individuals.
• High Mutation Rate: These regions are prone to mutations, with the number of repeats frequently changing. This variability makes them ideal genetic markers.
• Genome Distribution: Scattered throughout the genome, microsatellites are often found in non-coding regions, but can also be present within genes.

Why are microsatellites important?

• Genetic Diversity: The high mutation rate of microsatellites leads to variations in the number of repeats between individuals. This variation serves as a fingerprint, allowing researchers to assess genetic diversity within populations.
• Population Genetics: By analyzing microsatellite variation, scientists can study population structure, migration patterns, and relatedness between individuals.
• Forensics: Microsatellites are powerful tools in forensic science for individual identification due to their high variability and abundance throughout the genome.

What are applications of microsatellites in practice?

• Paternity Testing: Microsatellite analysis can be used to determine biological parentage by comparing microsatellite profiles of offspring and potential fathers.
• Conservation Genetics: Studying microsatellite variation helps assess genetic diversity in endangered populations, informing conservation strategies.
• Genetic Mapping: Microsatellites can be used to create genetic maps, which visualize the relative positions of genes on chromosomes.

Practical example

Imagine studying a population of cheetahs. Researchers can analyze microsatellite variations to estimate the genetic diversity within the population. Low diversity could indicate inbreeding, a threat to the population's health. This information can guide conservation efforts to promote breeding between unrelated individuals.

Critical comments

• While powerful, microsatellites are not foolproof for individual identification. Analysing multiple markers is crucial for robust results.
• Null alleles, where an individual lacks a particular microsatellite region, can complicate analysis and require additional considerations.
• Microsatellites are primarily used for studying neutral genetic variation and may not directly reflect functional traits.