Como funciona a tecnologia de seleção de grandes fragmentos de DNA no sequenciamento NGS

A tecnologia de seleção de grandes fragmentos de DNA desempenha um papel crítico no sequenciamento NGS, particularmente na detecção de variantes estruturais, montagem do genoma, e análise de haplótipos. Abaixo estão suas principais aplicações e princípios técnicos:：

EU. Cenários de aplicação

Structural Variant (SV) Detection

Challenge: Conventional short-read sequencing (por exemplo, Illumina) struggles to accurately capture variants >1 KB (insertions, deletions, inversions, translocations).

Solução: By selecting large DNA fragments (10–50 kb) for library construction, combined with long-read sequencing (PacBio/Nanopore) or linked-read analysis, complex SVs spanning repetitive regions can be resolved.

Exemplo: Fusion events in cancer genomes (por exemplo, *ALK-EML4*) often require large-fragment data.

High-Quality Genome Assembly

Challenge: Short-read data often leads to assembly errors in repetitive regions, causing genome fragmentation.

Solução: Large fragments (por exemplo, Fosmid libraries) provide long-range physical linkage, enabling continuous scaffold assembly (5–10× improvement in N50).

Exemplo: The T2T Consortium filled the final 8% gap in the human reference genome using Hi-C and ultra-long-read technologies.

Haplotype Phasing

Challenge: Short-read sequencing fails to preserve allelic linkage at heterozygous sites.

Solução: Barcode-based technologies (por exemplo, 10X Genomics) reconstruct haplotype blocks spanning hundreds of kb.

Value: Critical for HLA typing and identifying disease-causing gene linkages.

II. Core Selection Technologies

1. Physical Separation Methods

Eletroforese em gel de campo de pulso (PFGE): Separates fragments >50 kb for metagenomic or complex sample screening.

Magnetic Bead Selection (SPRIselect): Recovers specific fragment sizes (por exemplo, 0.1–10 kb or >15 KB) by adjusting bead-to-sample ratios.

2. Barcode-Based Enrichment

10X Genomics Chromium: Encapsulates DNA fragments in oil droplets, labeling short reads from the same large fragment with barcodes.

TELL-Seq/Linked-Reads: Uses microfluidics for virtual long-fragment reconstruction at 50% lower cost than 10X.

3. Circularization-Based Amplification

Loop Genomics: DNA fragments are circularized and amplified via rolling circle replication, preserving physical adjacency for standard NGS platforms.

III. Advantages vs. Conventional Methods

4. Challenges and Optimization

High DNA Quality Required: Needs intact DNA (DV200 >50%), incompatible with FFPE samples to Development of low-damage extraction kits.

Cost Control: Long-read sequencing remains expensive to Hybrid strategies (por exemplo, Linked-Reads and Illumina) reduzir custos.

Bioinformatics Upgrades: Specialized tools needed (por exemplo, Canu for assembly, HapCUT2 for phasing).

V. Representative Applications

COVID-19 Tracing: Nanopore sequencing and magnetic bead selection (>20 kb fragments) rapidly resolved SARS-CoV-2 genomes and recombination events.

Genetic Disease Diagnosis: 10X Genomics detected SMN1 exon 7 deletions, avoiding interference from SMN2.

Plant Genomics: In barley genome assembly, BAC libraries (40–100 kb) increased Contig N50 to 486 KB.

Conclusão

Large DNA fragment selection overcomes the limitations of short-read NGS by providing long-range genomic context. With advances in barcoding (por exemplo, TELL-Seq) and localized platforms (por exemplo, MGI CoolMPS), this technology will accelerate applications in clinical diagnostics, evolutionary studies, and precision breeding.

Fornecedor

Xangai Lingjun Biotecnologia Co., Ltda.foi estabelecido em 2016 que é um fabricante profissional de materiais biomagnéticos e reagentes de extração de ácido nucleico.

Temos vasta experiência em extração e purificação de ácidos nucleicos, purificação de proteínas, separação celular, quimioluminescência, e outras áreas técnicas.

Nossos produtos são amplamente utilizados em muitos campos, como exames médicos, testes genéticos, pesquisa universitária, melhoramento genético, e assim por diante. Nós não apenas fornecemos produtos, mas também podemos realizar OEM, ODM, e outras necessidades. Se você tiver uma necessidade relacionada, não hesite em contactar-nos .