Solexa sequencing, also known as sequencing by synthesis (SBS), was an early next-generation sequencing (NGS) technology developed by Solexa Ltd., which is now part of Illumina. Here are the key features and characteristics of Solexa sequencing:

– Principle of Sequencing: Solexa sequencing operates on the principle of sequencing by synthesis. During the sequencing process, fluorescently labeled nucleotides are added one at a time to the growing DNA strand. Each incorporation event is detected by fluorescence imaging.

– Technology Platform: It utilizes reversible terminators for nucleotide addition, where each nucleotide is labeled with a unique fluorophore that emits light upon incorporation. After detection, the fluorophore and blocking group are removed to allow the next nucleotide addition.

– High Throughput: Solexa sequencing is characterized by high throughput capabilities, allowing for the simultaneous sequencing of millions of DNA fragments in a single run. This massively parallel sequencing approach significantly accelerates the sequencing process compared to traditional Sanger sequencing.

– Short Read Lengths: Initially, Solexa sequencing produced relatively short read lengths compared to current NGS technologies. Early iterations typically generated reads of around 30 to 50 base pairs in length.

– Accuracy and Error Rates: It offers high accuracy in base calling, with low error rates. This is crucial for applications requiring precise sequence information, such as genome sequencing, variant detection, and transcriptome analysis.

– Applications: Solexa sequencing has been instrumental in various fields of genomic research, including whole-genome sequencing, RNA sequencing (RNA-Seq), ChIP sequencing (ChIP-Seq), metagenomics, and epigenetics.

– Evolution into Illumina Sequencing: The Solexa technology platform was further developed and commercialized by Illumina after its acquisition of Solexa Ltd. in 2007. Illumina’s sequencing systems continue to evolve, with improvements in read lengths, throughput, and cost-effectiveness.

In summary, Solexa sequencing pioneered the era of NGS technologies by enabling high-throughput, massively parallel sequencing with high accuracy. Its principles of sequencing by synthesis laid the foundation for subsequent advancements in genomic research and personalized medicine.