Splicing

Splicing refers to the act of joining parts to form a continuous whole and is used in several fields, notably biology and materials engineering. In molecular biology, splicing most often denotes RNA splicing, the processing of precursor messenger RNA (pre-mRNA) to remove noncoding segments and join coding segments. In engineering, splicing describes methods for joining materials such as DNA constructs or optical fibers so as to create continuous sequences or networks.

In RNA splicing, pre-mRNA in eukaryotic cells contains exons that encode protein and introns that do not. The spliceosome, a complex of small nuclear RNAs and proteins, recognizes conserved sequences at the 5' and 3' ends of introns and a branch point. The reaction removes the intron as a lariat and links adjacent exons to generate mature mRNA. Alternative splicing can produce multiple mRNA and protein isoforms from a single gene, increasing proteome diversity. Splicing is tightly regulated by splicing factors and RNA sequence motifs; errors in splicing can contribute to diseases such as spinal muscular atrophy, certain cancers, and other genetic disorders.

In genetic engineering, splicing often refers to joining DNA fragments to construct genes or plasmids. This is typically achieved with enzymes such as DNA ligases or through recombination-based methods, enabling the assembly of recombinant molecules for research, therapy, or biotechnology. A related concept is protein splicing, where proteins containing an internal segment called an intein removes itself and covalently joins the surrounding segments (exteins), a process used in protein engineering.

In fiber optics, splicing is the method of connecting fiber optic cables. Fusion splicing uses heat to fuse fiber ends together, minimizing signal loss and back reflection. Mechanical splices place connectors or sleeves to join fibers, offering quicker but typically less low-loss connections. Splicing is essential for long-distance communication networks and data transmission infrastructure.