Sequencing Technology Technology
What is Sequencing Technology?
Sequencing Technology refers to the various high-throughput methods used to determine the precise order of nucleotides (adenine, guanine, cytosine, and thymine) within a DNA molecule. These technologies have revolutionized genomics, metagenomics, and microbiome research.
Common Sequencing Technologies
16S rRNA Sequencing
- Purpose: Identify and classify bacteria in microbiome samples
- Target: 16S ribosomal RNA gene (present in all bacteria)
- Applications: Microbial diversity analysis, taxonomic profiling
- Advantages: Cost-effective, well-established reference databases
- Limitations: Cannot distinguish between closely related species, no functional information
18S rRNA Sequencing
- Purpose: Identify and classify eukaryotic microbes (fungi, protists)
- Target: 18S ribosomal RNA gene
- Applications: Eukaryotic microbiome analysis, environmental surveys
ITS Sequencing
- Purpose: Fungal identification and classification
- Target: Internal Transcribed Spacer region
- Applications: Mycobiome studies, fungal diversity assessment
Shotgun Metagenomics (WGS)
- Purpose: Sequence all DNA in a sample
- Target: Entire genomic content
- Applications: Comprehensive microbial profiling, functional gene analysis, strain-level identification
- Advantages: Detects bacteria, viruses, fungi, archaea; provides functional potential
- Limitations: More expensive, computationally intensive
Whole Genome Sequencing (WGS)
- Purpose: Complete genome sequencing of individual organisms
- Target: Entire genome of a single organism
- Applications: Genomic characterization, comparative genomics, variant analysis
Illumina Sequencing
- Technology: Sequencing by synthesis (SBS)
- Key Features: Short reads (75-300 bp), high accuracy, high throughput
- Instrument Models: HiSeq, MiSeq, NovaSeq, NextSeq
- Applications: Genomics, metagenomics, transcriptomics
Oxford Nanopore
- Technology: Nanopore-based electrical detection
- Key Features: Long reads (>1 Mb), portable devices (MinION), real-time analysis
- Advantages: No amplification bias, detects base modifications
- Limitations: Higher error rate than Illumina
PacBio SMRT Sequencing
- Technology: Single-molecule real-time sequencing
- Key Features: Long reads (average 10-25 kb), high accuracy with circular consensus
- Applications: Complete genome assembly, structural variant detection, epigenetics
Sequencing in CMMI-DCC
In the CMMI Data Coordinating Center:
- Metagenomics: Uses various sequencing technologies for microbiome analysis
- Microbiome Studies: 16S rRNA, 18S rRNA, and ITS sequencing for taxonomic profiling
- Sample Types: Different sequencing approaches for stool, oral, skin, and environmental samples
- Data Analysis: Bioinformatics pipelines for quality control, assembly, and annotation
Workflow Overview
- Sample Preparation: DNA extraction from sample
- Library Preparation: Fragmentation and adapter ligation
- Sequencing: Run on sequencing instrument
- Base Calling: Conversion of raw signals to nucleotide sequences
- Quality Control: Filtering low-quality reads and contaminants
- Analysis: Taxonomic assignment, functional annotation, or assembly
Instrument Models in CMMI-DCC
Common sequencing platforms include:
- Illumina MiSeq: Smaller runs, 16S/18S/ITS amplicon sequencing
- Illumina HiSeq: Large-scale metagenomics projects
- Illumina NovaSeq: Ultra-high throughput studies
- Oxford Nanopore MinION: Portable, field sequencing
Data Characteristics
- Read Length: Short (Illumina) vs. Long (Nanopore, PacBio)
- Throughput: Millions to billions of reads per run
- Accuracy: Varies by platform (99.9% for Illumina, 95-99% for others)
- Cost: Depends on platform, read depth, and sample number
Related Terms
- Metagenomics: Study of genetic material recovered from environmental samples
- Microbiome: Collection of microorganisms in a specific environment
- Alpha Diversity: Measure of microbial diversity within a sample
- Sample Type: Biological material being sequenced (stool, saliva, etc.)
References
- Sequencing technology principles and applications
- Metagenomics analysis guidelines
- Microbiome research standards