Endogeneetsust

Endogeneetsust is a term used within comparative genomics and evolutionary biology to describe a class of genetic elements that are derived from ancestral endosymbiotic organisms and have become stably integrated into the genome of a host organism. The word is a portmanteau of “endogenous,” “gene,” and “extinction,” highlighting the dual nature of these elements: they originate from extinct or degenerated genomes yet persist as functional or pseudogenic sequences in the host.

These elements were first identified in early 2010s analyses of eukaryotic genomes where large segments of bacterial and archaeal DNA had been retained following ancient symbiotic events. Unlike typical horizontal gene transfer, endogeneetsust sequences are ancient, spanning millions of years, and are often found in conserved loci across related species. Their retention is usually driven by positive selective pressures; many encode proteins involved in metabolism, stress response, or immune signaling.

Research on endogeneetsust also helps clarify the timing and extent of genome reduction in mitochondria and chloroplasts, as some of these sequences are homologous to genes lost in these organelles. Because they can provide adaptive advantages, endogeneetsust are sometimes reactivated under certain environmental conditions, leading to phenotypic changes.

The study of these sequences remains an active field, with advances in sequencing technologies and bioinformatics pipelines enabling more accurate identification and annotation. Scientists use them to reconstruct phylogenetic relationships, understand the mechanisms of genome integration, and explore the evolutionary benefits of endosymbiotic gene transfer.