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From Empedocles to Symbiogenetics: Lynn Margulis's revolutionary influence on evolutionary biology. Biosystems 2021; 204:104386. [PMID: 33621579 DOI: 10.1016/j.biosystems.2021.104386] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 02/12/2021] [Indexed: 02/07/2023]
Abstract
As a primary expositor of the work of Lynn Margulis collaborating with her over thirty years on over thirty books and forty articles, scientific and popular, I attempt here to summarize her unique and lasting influence on evolutionary biology. Describing life on Earth as the multi-billion-year evolution of microbial communities, from prokaryotes maintaining Earth's atmosphere away from thermodynamic equilibrium to all eukaryotes as polygenomic beings, Margulis's interdisciplinary work has deeply influenced multiple fields including systematics, theories of the evolution of metabolism, paleobiology, and biogeochemistry. Overturning the neo-Darwinist narrative that speciation almost always occurs by the gradual accumulation of random mutations, Margulis's work revives a discarded philosophical speculation of the pre-Socratic Empedocles, who suggested that Earth's early beings both merged and differentially reproduced (were naturally selected); a speculation that was rejected by Aristotle probably because it smacked of mythological chimeras that had no place in observational biology, and later by Charles Darwin, who mentioned Aristotle's rejection of Empedocles to show that he knew of but did not accept natural selection, thus helping lay his own claim to its own proper scientific presentation in a Victorian culture whose thinking of origins was dominated not by Greek mythology but Christian special creation. Margulis's curiosity-driven science, collaborative work ethic, status as a woman, embrace of novelty, philosophical stance, current status of her theories, and the proposal for a new science of symbiogenetics are among the topics examined.
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Khatiwada B, Hasan MT, Sun A, Kamath KS, Mirzaei M, Sunna A, Nevalainen H. Probing the Role of the Chloroplasts in Heavy Metal Tolerance and Accumulation in Euglena gracilis. Microorganisms 2020; 8:E115. [PMID: 31947612 PMCID: PMC7023027 DOI: 10.3390/microorganisms8010115] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/11/2020] [Accepted: 01/12/2020] [Indexed: 12/02/2022] Open
Abstract
The E. gracilis Zm-strain lacking chloroplasts, characterized in this study, was compared with the earlier assessed wild type Z-strain to explore the role of chloroplasts in heavy metal accumulation and tolerance. Comparison of the minimum inhibitory concentration (MIC) values indicated that both strains tolerated similar concentrations of mercury (Hg) and lead (Pb), but cadmium (Cd) tolerance of the Z-strain was twice that of the Zm-strain. The ability of the Zm-strain to accumulate Hg was higher compared to the Z-strain, indicating the existence of a Hg transportation and accumulation mechanism not depending on the presence of chloroplasts. Transmission electron microscopy (TEM) showed maximum accumulation of Hg in the cytosol of the Zm-strain and highest accumulation of Cd in the chloroplasts of the Z-strain indicating a difference in the ability of the two strains to deposit heavy metals in the cell. The highly abundant heavy metal transporter MTP2 in the Z-strain may have a role in Cd transportation to the chloroplasts. A multidrug resistance-associated protein highly increased in abundance in the Zm-strain could be a potential Hg transporter to either cytosol or mitochondria. Overall, the chloroplasts appear to have major role in the tolerance and accumulation of Cd in E. gracilis.
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Affiliation(s)
- Bishal Khatiwada
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
| | - Mafruha T. Hasan
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
| | - Angela Sun
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
| | - Karthik Shantharam Kamath
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
- Australian Proteome Analysis Facility, Macquarie University, Sydney, NSW 2109, Australia
| | - Mehdi Mirzaei
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
- Australian Proteome Analysis Facility, Macquarie University, Sydney, NSW 2109, Australia
| | - Anwar Sunna
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
| | - Helena Nevalainen
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia; (B.K.); (M.T.H.); (A.S.); (K.S.K.); (M.M.)
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW 2109, Australia
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Ultrastructural organization of secondary mutants ofEuglena gracilis induced by N-methyl-N′-nitro-N-nitrosoguanidine. Folia Microbiol (Praha) 1990. [DOI: 10.1007/bf02821412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Nigon V, Heizmann P. Morphology, Biochemistry, and Genetics of Plastid Development in Euglena gracilis. INTERNATIONAL REVIEW OF CYTOLOGY 1978. [DOI: 10.1016/s0074-7696(08)62243-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Ferrara R, Banchetti R. Effect of streptomycin on the structure and function of the photoreceptor apparatus of Euglena gracilis. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1976; 198:393-402. [PMID: 826601 DOI: 10.1002/jez.1401980313] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The progressive modification of the photoreceptor apparatus, induced by addition of streptomycin (SM) to cultures of dark-bleached Euglena, is correlated with the change of the photomotor response. One of the effects of drug-treatment is the reduction of carotenoid synthesis; the total carotenoid content decreases from 0.20 to 0.01 pg/cell after seven weeks of treatment. The parallel progressive reduction of the stigma vesicles and their carotenoid content is observed by electron microscopy. Micrographs and microscopic fluorescence observations do not indicate alterations of the paraflagellar body (PFB). During the SM-treatment the initial positive phototactic response decreases until it disappears after five weeks. The loss of the absorbing properties of the stigma prevents the cell from orienting itself towards the light. The probability that the cell orients seems to depend on the light modulation amplitude and the light/dark ratio on the PFB due to the shading device. After seven weeks of SM-treatment we observe a cell movement away from the illuminated zone. The mechanism of this escape is discussed.
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