Spirochete contributions to the eukaryotic genome

Lynn Margulis and Boris Kozo-Polyansky: How the Symbiogenesis was translated from Russian

This contribution details the complex history of the early work by Boris Kozo-Polyansky (1924) that became available in English translation 86 years after it was published in Russian. The great American naturalist Lynn Margulis-whose serial endosymbiosis theory was presciently predated by Kozo-Polyansky by four decades-was instrumental in organizing this resurrection and 'horizontal transfer' of knowledge, forgotten by that time even in Russia.

A symbiotic view of life: we have never been individuals

The notion of the "biological individual" is crucial to studies of genetics, immunology, evolution, development, anatomy, and physiology. Each of these biological subdisciplines has a specific conception of individuality, which has historically provided conceptual contexts for integrating newly acquired data. During the past decade, nucleic acid analysis, especially genomic sequencing and high-throughput RNA techniques, has challenged each of these disciplinary definitions by finding significant interactions of animals and plants with symbiotic microorganisms that disrupt the boundaries that heretofore had characterized the biological individual. Animals cannot be considered individuals by anatomical or physiological criteria because a diversity of symbionts are both present and functional in completing metabolic pathways and serving other physiological functions. Similarly, these new studies have shown that animal development is incomplete without symbionts. Symbionts also constitute a second mode of genetic inheritance, providing selectable genetic variation for natural selection. The immune system also develops, in part, in dialogue with symbionts and thereby functions as a mechanism for integrating microbes into the animal-cell community. Recognizing the "holobiont"--the multicellular eukaryote plus its colonies of persistent symbionts--as a critically important unit of anatomy, development, physiology, immunology, and evolution opens up new investigative avenues and conceptually challenges the ways in which the biological subdisciplines have heretofore characterized living entities.