Gensegmente

Gensegmente, or gene segments in English, are discrete sequence blocks within a genome that together encode a gene or regulatory module. In genomics, segments can include coding exons, untranslated regions, promoters, enhancers, or modular domains within proteins. Segments may be dispersed across a gene locus or arranged in tandem, and their boundaries are defined by transcriptional, splicing, or chromatin features. Understanding segment organization aids gene annotation, comparative genomics, and studies of gene expression.

In vertebrate immune systems, gene segments such as V, D, and J segments encode immunoglobulin and T-cell receptor genes. These segments are assembled through V(D)J recombination during lymphocyte development, generating a diverse repertoire of receptors. The process involves recombination-activating genes RAG1 and RAG2 and additional diversification at junctions. The number and organization of segments vary by species and gene family, influencing immune diversity.

Many RNA viruses also have segmented genomes, comprising multiple gene segments. For example, influenza A, influenza B, and rotaviruses store their genes on separate segments. Segmentation allows genetic reassortment when two different strains co-infect a host cell, promoting rapid variation in surface proteins and potentially altering virulence and host range. In genomics, segmentation is a key consideration in assembly and evolutionary studies.

In modern genome annotation, segments correspond to structured units such as exons and regulatory motifs. Alternative splicing can combine exons into multiple transcript variants, illustrating that segments may be reused in diverse configurations. Gensegmente thus describe the modular architecture of genes and genomes across biology.