VI. Earth Life Emergence: Development of Body, Brain, Selves and Societies
4. Cellular Holobiont Symbiogenesis
Kravchenko-Balasha, Nataly, et al. On a Fundamental Structure of Gene Networks in Living Cells. Proceedings of the National Academy of Sciences. 109/4702, 2012. In similar fashion to work by Keith Farnsworth, et al, and Melody Morris, et al (search each) Hebrew University of Jerusalem, UCLA, Weizmann Institute of Science Israel, and Universite de Liege, Belgium proceed by way of computational logics with deeper perceptions into these dynamic, sustaining topologies from genomics to cellularity phases.
Computers are organized into hardware and software. Using a theoretical approach to identify patterns in gene expression in a variety of species, organs, and cell types, we found that biological systems similarly are comprised of a relatively unchanging hardware-like gene pattern. Orthogonal patterns of software-like transcripts vary greatly, even among tumors of the same type from different individuals. Two distinguishable classes could be identified within the hardware-like component: those transcripts that are highly expressed and stable and an adaptable subset with lower expression that respond to external stimuli. Importantly, we demonstrate that this structure is conserved across organisms. The approach provides a conceptual thermodynamic-like framework for the analysis of gene expression levels and networks and their variations in diseased cells. (Abstract)
Lake, James. Evidence for an Early Prokaryotic Endosymbiosis. Nature. 460/967, 2009. Although the evolutionary formation of nucleated eukaryotic cells is now well attributed to mutual joinings and engulfments of diversified bacteria, that these simpler components also arose in such manner has not been considered. Here a UCLA astrobiologist “presents evidence that the double-membrane, gram negative prokaryotes were formed as the result of a symbiosis between an ancient actinobacterium and an ancient clostridium.” Lake closes this feature article by musing that such a reconstructed pathway of life’s cellular procession seems so apt that it could not have occurred by accident.
I cannot help but notice that the existence of the double-membrane structure immediately suggests a possible mechanism for its formation and for the observed genome transfers from Clostridia and Actinobacteria to the double-membrane prokaryotes – endosymbiosis. I believe that this agreement should not be ascribed to chance. (970)
Lane, Christopher and John Archibald. The Eukaryotic Tree of Life. Trends in Ecology and Evolution. 23/5, 2008. Canadian biologists contend that an appreciation of the pervasive role of endosymbiotic activity amongst the evolution and nature of nucleated cells will require a revision of life’s branching course. A companion article The Prokaryotic Tree of Life by James McInerney, et al, goes on to wonder if the “tree” motif which harks back to Lamarck and Haeckel is appropriate at all, rather a web-like “network” may be better. But such approaches remain constrained by their purview of molecular gene and corporeal soma alone. If a cerebral intelligence is added, a directional trunk accrues, which changes everything.
Latorre, Amparo, et al. The Role of Symbiosis in Eukaryotic Evolution. Gargaud, Muriel, et al, eds. Origins and Evolution of Life: An Astrobiological Perspective. Cambridge: Cambridge University Press, 2011. With coauthors Ana Durban, Andres Moya and Juli Pereto of the Institut Cavanilles de Biodiversitat I Biologia Evolution, Valencia, a succinct chapter about the latest insights into nature’s preference for mutual assemblies of disparate components across a broad realm of living functions and activities. And as we log this on November 29, 2011, we want to record the sudden passing on November 22 at age 73 of Lynn Margulis, the redoubtable founder of this theory and advocate of life’s propensity to join, evolve, and emerge by persistent symbiosis. I had heard her introduce Robert Hazen just two weeks before when he spoke at near by University of Massachusetts at Amherst, where Lynn was professor of biology. She was tireless in her defense of this now proven theory, and in her enthusiasm with and time for students. The University and scientific community are in a state of shock at the loss of this international superstar.
In a broad sense, symbiosis could be defined as a long-term association between two or more organisms of different species at the behavioural, metabolic or genetic level. (326)
Lim, Shen Jean and Seth Bordenstein. An Introduction to Phylosymbiosis. Proceedings of the Royal Society B. Vol. 287/Iss. 1922, 2020. Vanderbilt University biologists (search SB) describe and illustrate this new found way that life well avails the benefits of myriad microbe-host communities. The survey covers, for example, plant roots, insect guts, aquatic creatures, land animals such as rodents and primates, and more. See also A Bird’s Eye View of Phylosymbiosis by Brian Trevelline, et al in this journal, Issue 1923, which reports upon avian instances.
Phylosymbiosis was formulated to support a hypothesis-driven framework for the characterization of a cross-system trend in host-associated microbiomes. Defining phylosymbiosis as ‘microbial community relationships that recapitulate the phylogeny of their host’, we review its literature and data. Quantitative proof is provided by statistical methods evaluating higher microbiome variation between host species than within host species, and a positive association between host genetic relationships and microbiome beta diversity. Significant degrees of phylosymbiosis are prevalent in microbiomes of plants and animals from terrestrial and aquatic habitats. Its pervasiveness carries several important implications for advancing knowledge of eco-evolutionary processes that impact host–microbiome interactions and future applications of precision microbiology. (Abstract excerpt)
Lloyd, Elisabeth and Michael Wade. Criteria for Holobionts from Community Genetics. Biological Theory. 14/3, 2019. We note this entry by a veteran Indiana University philosopher and biologist as a thorough, evenhanded review of this increasingly popular symbiotic concept of organisms from critters to sapiens. After some clarifications and caveats, by a proper understanding of life’s levels of selection, the holobiont model is a viable model of internal and external mutualisms.
Lopez-Garcia, Purificacion and David Moreira. Selective Forces for the Origin of the Eukaryotic Nucleus. BioEssays. 28/5, 2006. Further confirmations on how symbiotic syntheses serve to form the nucleated cell.
We propose here an evolutionary scenario that reconciles both an ancestral endosymbiotic origin of the eukaryotic nucleus with an autogenous generation of the contemporary nuclear membrane and ER (endoplasmic reticulum) from the bacterial membrane. (525)
Ma’ayan, Avi, et al. Toward Predictive Models of Mammalian Cells. Annual Review of Biophysics and Biomolecular Structure. 34/319, 2005. In this century of systems biology, a new understanding of cells is in process as more than the collection of parts we learned in high school. Many approaches now describe equally real interrelations between resident networks and modules whereby cells become another microcosm of universal self-organization and autopoietic self-maintenance. Among other topics, the chapter surveys small-world network principles, nested modularity, a constant cross-talk, and how to represent and predict cellular intra- and inter-activities.
Mann, Stephen. Life as a Nanoscale Phenomenon. Angewandte Chemie. 47/5306, 2008. As the quotes convey, the University of Bristol systems chemist provides an extensive, illustrated survey of the archetypal cell as a complex, dynamical, self-generating whole. The autopoiesis model of Maturana and Varela is availed as a guiding theory for both self-maintenance and a relational “cognition.”
The nanoscale is not just the middle ground between molecular and macroscopic but a dimension that is specifically geared to the gathering, processing, and transmission of chemical-based information. Herein we consider the living cell as an integrated self-regulating complex chemical system run principally by nanoscale miniaturization, and propose that this specific level of dimensional constraint is critical for the emergence and sustainability of cellular life in its minimal form. We address key aspects of the structure and function of the cell interface and internal metabolic processing that are coextensive with the up-scaling of molecular components to globular nanoobjects (integral membrane proteins, enzymes, and receptors, etc) and higher order architectures such as microtubules, ribosomes, and molecular motors. (Abstract, 5306)
Margulis, Lynn. Symbiosis in Cell Evolution. San Francisco: Freeman, 1992. The main reference for how the symbiotic evolution and assembly of eukaryotic cells became known by its University of Massachusetts at Amherst microbiologist who discovered it.
Margulis, Lynn and Rene Fester, eds. Symbiosis as a Source of Innovation in Evolution. Cambridge: MIT Press, 1991. A wide range of papers on the important role of symbiotic combinations in speciation and morphogenesis
Margulis, Lynn, et al, eds.
Chimeras and Consciousness: Evolution of the Sensory Self.
Cambridge: MIT Press,
As usual Lynn, Dorion Sagan, and colleagues achieve a unique, lively collection with five ascendant sections: Selves, Groups, Earth, Chimeras, and Consciousness. Again its core theme, in contrast to Darwinian denials, recognizes and expresses life’s inherent, persistent tendency toward manifest personal and communal individuality. Authoritative authors such as Eshel Ben Jacob, Antonio Lazcano, Margaret McFall-Nagi, Gerhard Roth, and Frank Ryan enlighten and enliven.
Chimeras and Consciousness begins the inquiry into the evolution of the collective sensitivities of life. Scientist-scholars from a range of fields--including biochemistry, cell biology, history of science, family therapy, genetics, microbial ecology, and primatology--trace the emergence and evolution of consciousness. Complex behaviors and the social imperatives of bacteria and other life forms during 3,000 million years of Earth history gave rise to mammalian cognition. Awareness and sensation led to astounding activities; millions of species incessantly interacted to form our planet’s complex conscious system. Our planetmates, all of them conscious to some degree, were joined only recently by us, the aggressive modern humans.