1
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Haverinen J, Badr A, Eskelinen M, Vornanen M. Three steps down: Metabolic depression in winter-acclimatized crucian carp (Carassius carassius L.). Comp Biochem Physiol A Mol Integr Physiol 2024; 287:111537. [PMID: 37858704 DOI: 10.1016/j.cbpa.2023.111537] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 10/13/2023] [Accepted: 10/15/2023] [Indexed: 10/21/2023]
Abstract
Acclimatization of certain ectothermic vertebrates to winter conditions is associated with reduced energy consumption (winter dormancy). Principally, this may be achieved by reducing movement activity, depression of basal cellular functions, or by switching from aerobic to anaerobic energy production to sustain low energy consumption during anoxia. Therefore, we determined standard (SMR), routine (RMR) and anoxic (AMR) metabolic rates in summer- (SumA; 20 °C) and winter-acclimatized (WinA; 2 °C) crucian carp (Carassius carassius), an anoxia-tolerant teleost fish. At 20 °C, RMR was 39% lower in WinA than SumA fish (p < 0.05), indicating reduced movements in winter. SMR, measured for the first time in crucian carp, was 45% lower in WinA than SumA fish at 10 °C (p < 0.05), indicating significant reduction of energy consumption in vital cellular processes. At 2 °C, AMR - measured from ethanol production- was 78% and 97% of the SMR and RMR levels at the same temperature, respectively. The current study revealed that the winter dormancy in anoxia-tolerant crucian carp is achieved in 3 different steps: (1) by active reduction of SMR, possibly in anticipation of seasonal anoxia, (2) acute Arrhenius Q10 effect that slows SMR as well as RMR, and (3) direct response to the absence of oxygen (AMR). Furthermore, the anoxic energy production was strongly dependent on body mass with scaling exponents of -0.335 and - 0.421 for WinA and SumA fish, respectively.
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Affiliation(s)
- Jaakko Haverinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland.
| | - Ahmed Badr
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland; Zoology Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt
| | - Markus Eskelinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland
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2
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Akingbesote ND, Leitner BP, Jovin DG, Desrouleaux R, Owusu D, Zhu W, Li Z, Pollak MN, Perry RJ. Gene and protein expression and metabolic flux analysis reveals metabolic scaling in liver ex vivo and in vivo. eLife 2023; 12:e78335. [PMID: 37219930 PMCID: PMC10205083 DOI: 10.7554/elife.78335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/08/2023] [Indexed: 05/24/2023] Open
Abstract
Metabolic scaling, the inverse correlation of metabolic rates to body mass, has been appreciated for more than 80 years. Studies of metabolic scaling have largely been restricted to mathematical modeling of caloric intake and oxygen consumption, and mostly rely on computational modeling. The possibility that other metabolic processes scale with body size has not been comprehensively studied. To address this gap in knowledge, we employed a systems approach including transcriptomics, proteomics, and measurement of in vitro and in vivo metabolic fluxes. Gene expression in livers of five species spanning a 30,000-fold range in mass revealed differential expression according to body mass of genes related to cytosolic and mitochondrial metabolic processes, and to detoxication of oxidative damage. To determine whether flux through key metabolic pathways is ordered inversely to body size, we applied stable isotope tracer methodology to study multiple cellular compartments, tissues, and species. Comparing C57BL/6 J mice with Sprague-Dawley rats, we demonstrate that while ordering of metabolic fluxes is not observed in in vitro cell-autonomous settings, it is present in liver slices and in vivo. Together, these data reveal that metabolic scaling extends beyond oxygen consumption to other aspects of metabolism, and is regulated at the level of gene and protein expression, enzyme activity, and substrate supply.
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Affiliation(s)
- Ngozi D Akingbesote
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Brooks P Leitner
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Daniel G Jovin
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Reina Desrouleaux
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Comparative Medicine, Yale UniversityNew HavenUnited States
| | - Dennis Owusu
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Wanling Zhu
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Zongyu Li
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
| | - Michael N Pollak
- Lady Davis Institute for Medical Research, Jewish General HospitalMontrealCanada
- Department of Oncology, McGill UniversityMontrealCanada
| | - Rachel J Perry
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Internal Medicine – Endocrinology, Yale UniversityNew HavenUnited States
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3
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On the natural selection of body mass allometries. ACTA OECOLOGICA 2023. [DOI: 10.1016/j.actao.2023.103889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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4
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Smith TP, Mombrikotb S, Ransome E, Kontopoulos DG, Pawar S, Bell T. Latent functional diversity may accelerate microbial community responses to temperature fluctuations. eLife 2022; 11:80867. [DOI: 10.7554/elife.80867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/26/2022] [Indexed: 11/30/2022] Open
Abstract
How complex microbial communities respond to climatic fluctuations remains an open question. Due to their relatively short generation times and high functional diversity, microbial populations harbor great potential to respond as a community through a combination of strain-level phenotypic plasticity, adaptation, and species sorting. However, the relative importance of these mechanisms remains unclear. We conducted a laboratory experiment to investigate the degree to which bacterial communities can respond to changes in environmental temperature through a combination of phenotypic plasticity and species sorting alone. We grew replicate soil communities from a single location at six temperatures between 4°C and 50°C. We found that phylogenetically and functionally distinct communities emerge at each of these temperatures, with K-strategist taxa favored under cooler conditions and r-strategist taxa under warmer conditions. We show that this dynamic emergence of distinct communities across a wide range of temperatures (in essence, community-level adaptation) is driven by the resuscitation of latent functional diversity: the parent community harbors multiple strains pre-adapted to different temperatures that are able to ‘switch on’ at their preferred temperature without immigration or adaptation. Our findings suggest that microbial community function in nature is likely to respond rapidly to climatic temperature fluctuations through shifts in species composition by resuscitation of latent functional diversity.
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Affiliation(s)
- Thomas P Smith
- The Georgina Mace Centre for the Living Planet, Imperial College London
| | - Shorok Mombrikotb
- The Georgina Mace Centre for the Living Planet, Imperial College London
| | - Emma Ransome
- The Georgina Mace Centre for the Living Planet, Imperial College London
| | | | - Samraat Pawar
- The Georgina Mace Centre for the Living Planet, Imperial College London
| | - Thomas Bell
- The Georgina Mace Centre for the Living Planet, Imperial College London
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5
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Rao R, Hu J, Lee PH. Theoretical characterisation of electron tunnelling from granular activated carbon to electron accepting organisms in direct interspecies electron transfer. Sci Rep 2022; 12:12426. [PMID: 35858919 PMCID: PMC9300713 DOI: 10.1038/s41598-022-15606-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 06/27/2022] [Indexed: 11/25/2022] Open
Abstract
Direct interspecies electron transfer (DIET) has been identified as an efficient metabolism between symbiotically interacting organisms. One method of DIET uses conductive materials (e.g., granular activated carbon (GAC)) as a medium to shuttle electrons from electron donating organisms (eg., Geobacter metallireducens) to electron accepting organisms (e.g., Geobacter sulfurreducens and Methanosarcina barkeri). Conductive materials such as GAC, become negatively charged in DIET processes due to reduction by electron donating organisms. This high excess electron density in GAC leads to quantum tunnelling of electrons being a significant electron transfer mechanism for DIET. Thus, a theoretical model obeying the Wentzel–Kramers–Brillouin (WKB) approximation and Fermi–Dirac statistics was developed and simulated. In the model, the electron tunnelling transfer barrier was described by an effective rectangular barrier. The result of our 1D tunnelling simulations indicates that within 29.4 nm of the GAC, tunnelling can sufficiently supply electrons from GAC to G. sulfurreducens and M. barkeri. The phenomenon of tunnelling may also have significance as a stimulant of chemotaxis for G. sulfurreducens and other electron accepting microbes when attempting to adsorb onto GAC. This study sheds light on quantum tunnelling’s significant potential in both bacterium and archaeon DIET-centric processes.
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Affiliation(s)
- Rohan Rao
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, UK.,Department of Physics, Oxford University, Oxford, UK
| | - Jing Hu
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, UK
| | - Po-Heng Lee
- Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, UK.
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6
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Zhang Y, Kowalski GJ. Calorimetric Measurements of Biological Interactions and Their Relationships to Finite Time Thermodynamics Parameters. ENTROPY 2022; 24:e24040561. [PMID: 35455224 PMCID: PMC9033059 DOI: 10.3390/e24040561] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 04/11/2022] [Accepted: 04/11/2022] [Indexed: 12/10/2022]
Abstract
A description and examination of the potential for calorimetry for use in exploring the entropy flows in biological and or reacting systems is presented. A calorimeter operation background is provided, and two case studies are investigated using a transient numerical simulation. The first case describes a single cell calorimeter containing a single phase material excited by heat generation source function such as joule heating. The second case is a reacting system. The basic observation parameter, the temperature, cannot be used to separate the entropy property changes and the rate of entropy production in the second case. The calculated transient response can be further analyzed to determine the equilibrium constant once the reaction equation and stoichiometric constants are specified which allows entropy property changes and the rate of entropy production to be determined. In a biological community, the equivalent of the reaction equation and a definition of an equilibrium constant are not available for all systems. The results for the two cases illustrate that using calorimetry measurements to identify the entropy flows in biological community activities requires further work to establish a framework similar to that chemical reacting systems that are based on an equilibrium type parameter.
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7
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Lantin S, Mendell S, Akkad G, Cohen AN, Apicella X, McCoy E, Beltran-Pardo E, Waltemathe M, Srinivasan P, Joshi PM, Rothman JH, Lubin P. Interstellar space biology via Project Starlight. ACTA ASTRONAUTICA 2022; 190:261-272. [PMID: 36710946 PMCID: PMC9881496 DOI: 10.1016/j.actaastro.2021.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Our ability to explore the cosmos by direct contact has been limited to a small number of lunar and interplanetary missions. However, the NASA Starlight program points a path forward to send small, relativistic spacecraft far outside our solar system via standoff directed-energy propulsion. These miniaturized spacecraft are capable of robotic exploration but can also transport seeds and organisms, marking a profound change in our ability to both characterize and expand the reach of known life. Here we explore the biological and technological challenges of interstellar space biology, focusing on radiation-tolerant microorganisms capable of cryptobiosis. Additionally, we discuss planetary protection concerns and other ethical considerations of sending life to the stars.
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Affiliation(s)
- Stephen Lantin
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, 32611, FL, USA
- Department of Chemical Engineering, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Sophie Mendell
- Department of Molecular, Cellular, and Developmental Biology, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
- College of Creative Studies, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Ghassan Akkad
- Department of Molecular, Cellular, and Developmental Biology, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Alexander N. Cohen
- Department of Physics, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Xander Apicella
- Department of Physics, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Emma McCoy
- Department of Physics, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | | | | | - Prasanna Srinivasan
- Department of Electrical and Computer Engineering, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
- Center for BioEngineering, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Pradeep M. Joshi
- Department of Molecular, Cellular, and Developmental Biology, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Joel H. Rothman
- Department of Molecular, Cellular, and Developmental Biology, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
| | - Philip Lubin
- Department of Physics, University of California - Santa Barbara, Santa Barbara, 93106, CA, USA
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8
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Metabolic limits on classical information processing by biological cells. Biosystems 2021; 209:104513. [PMID: 34450208 DOI: 10.1016/j.biosystems.2021.104513] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/14/2021] [Accepted: 08/14/2021] [Indexed: 01/16/2023]
Abstract
Biological information processing is generally assumed to be classical. Measured cellular energy budgets of both prokaryotes and eukaryotes, however, fall orders of magnitude short of the power required to maintain classical states of protein conformation and localization at the Å, fs scales predicted by single-molecule decoherence calculations and assumed by classical molecular dynamics models. We suggest that decoherence is limited to the immediate surroundings of the cell membrane and of intercompartmental boundaries within the cell, and that bulk cellular biochemistry implements quantum information processing. Detection of Bell-inequality violations in responses to perturbation of recently-separated sister cells would provide a sensitive test of this prediction. If it is correct, modeling both intra- and intercellular communication requires quantum theory.
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9
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Riedl RA, Burnett CML, Pearson NA, Reho JJ, Mokadem M, Edwards RA, Kindel TL, Kirby JR, Grobe JL. Gut Microbiota Represent a Major Thermogenic Biomass. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab019. [PMID: 33939772 PMCID: PMC8055641 DOI: 10.1093/function/zqab019] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 01/06/2023]
Abstract
Evidence supports various roles for microbial metabolites in the control of multiple aspects of host energy flux including feeding behaviors, digestive efficiency, and energy expenditure, but few studies have quantified the energy utilization of the biomass of the gut microbiota itself. Because gut microbiota exist in an anoxic environment, energy flux is expected to be anaerobic; unfortunately, commonly utilized O2/CO2 respirometry-based approaches are unable to detect anaerobic energy flux. To quantify the contribution of the gut microbial biomass to whole-animal energy flux, we examined the effect of surgical reduction of gut biomass in C57BL/6J mice via cecectomy and assessed energy expenditure using methods sensitive to anaerobic flux, including bomb and direct calorimetry. First, we determined that cecectomy caused an acceleration of weight gain over several months due to a reduction in combined total host plus microbial energy expenditure, as reflected by an increase in energy efficiency (ie, weight gained per calorie absorbed). Second, we determined that under general anesthesia, cecectomy caused immediate changes in heat dissipation that were significantly modified by short-term pretreatment with dietary or pharmaceutical interventions known to modify the microbiome, and confirmed that these effects were undetectable by respirometry. We conclude that while the cecum only contributes approximately 1% of body mass in the mouse, this organ contributes roughly 8% of total resting energy expenditure, that this contribution is predominantly anaerobic, and that the composition and abundance of the cecal microbial contents can significantly alter its contribution to energy flux.
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Affiliation(s)
- Ruth A Riedl
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Colin M L Burnett
- Department of Internal Medicine, Division of Cardiology, University of Iowa Hospitals & Clinics, Iowa City, IA, USA
| | - Nicole A Pearson
- Department of Laboratory Medicine and Pathology/Proteomics, Mayo Clinic, Rochester, MN, USA
| | - John J Reho
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA,Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Mohamad Mokadem
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, University of Iowa Hospitals & Clinics, Iowa City, IA, USA
| | - Robert A Edwards
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Tammy L Kindel
- Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA
| | - John R Kirby
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA,Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA,Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, USA,Center for Microbiome Research, Medical College of Wisconsin, Milwaukee, WI, USA,Address correspondence to J.L.G. (e-mail: ), J.R.K. (e-mail: )
| | - Justin L Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA,Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, WI, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI, USA,Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI, USA,Address correspondence to J.L.G. (e-mail: ), J.R.K. (e-mail: )
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10
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Rospars JP, Meyer-Vernet N. How fast do mobile organisms respond to stimuli? Response times from bacteria to elephants and whales. Phys Biol 2021; 18:026002. [PMID: 33232948 DOI: 10.1088/1478-3975/abcd88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quick responses to fast changes in the environment are crucial in animal behaviour and survival, for example to seize prey, escape predators, or negotiate obstacles. Here, we study the 'simple response time' that is the time elapsed between receptor stimulation and motor activation as typically shown in escape responses, for mobile organisms of various taxa ranging from bacteria to large vertebrates. We show that 95% of these simple response times lie within one order of magnitude of the overall geometric mean of about 25 ms, which is similar to that of a well-studied sensory time scale, the inverse of the critical flicker fusion frequency in vision, also lying within close bounds for all the organisms studied. We find that this time scale is a few times smaller than the minimum time to move by one body length, which is known to lie also within a relatively narrow range for all moving organisms. The remarkably small 102-fold range of the simple response time among so disparate life forms varying over 1020-fold in body mass suggests that it is determined by basic physicochemical constraints, independently on the structure and scale of the organism. We thus propose first-principle estimates of the simple response and sensory time scales in terms of physical constants and a few basic biological properties common to mobile organisms and constraining their responses.
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Affiliation(s)
- Jean-Pierre Rospars
- Institute of Ecology and Environmental Sciences of Paris, INRAE, Route de Saint-Cyr, 78000 Versailles, France
| | - Nicole Meyer-Vernet
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
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11
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Cytochrome c Oxidase at Full Thrust: Regulation and Biological Consequences to Flying Insects. Cells 2021; 10:cells10020470. [PMID: 33671793 PMCID: PMC7931083 DOI: 10.3390/cells10020470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 01/24/2023] Open
Abstract
Flight dispersal represents a key aspect of the evolutionary and ecological success of insects, allowing escape from predators, mating, and colonization of new niches. The huge energy demand posed by flight activity is essentially met by oxidative phosphorylation (OXPHOS) in flight muscle mitochondria. In insects, mitochondrial ATP supply and oxidant production are regulated by several factors, including the energy demand exerted by changes in adenylate balance. Indeed, adenylate directly regulates OXPHOS by targeting both chemiosmotic ATP production and the activities of specific mitochondrial enzymes. In several organisms, cytochrome c oxidase (COX) is regulated at transcriptional, post-translational, and allosteric levels, impacting mitochondrial energy metabolism, and redox balance. This review will present the concepts on how COX function contributes to flying insect biology, focusing on the existing examples in the literature where its structure and activity are regulated not only by physiological and environmental factors but also how changes in its activity impacts insect biology. We also performed in silico sequence analyses and determined the structure models of three COX subunits (IV, VIa, and VIc) from different insect species to compare with mammalian orthologs. We observed that the sequences and structure models of COXIV, COXVIa, and COXVIc were quite similar to their mammalian counterparts. Remarkably, specific substitutions to phosphomimetic amino acids at critical phosphorylation sites emerge as hallmarks on insect COX sequences, suggesting a new regulatory mechanism of COX activity. Therefore, by providing a physiological and bioenergetic framework of COX regulation in such metabolically extreme models, we hope to expand the knowledge of this critical enzyme complex and the potential consequences for insect dispersal.
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12
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Scilipoti S, Koren K, Risgaard-Petersen N, Schramm A, Nielsen LP. Oxygen consumption of individual cable bacteria. SCIENCE ADVANCES 2021; 7:7/7/eabe1870. [PMID: 33568484 PMCID: PMC7875522 DOI: 10.1126/sciadv.abe1870] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/23/2020] [Indexed: 05/24/2023]
Abstract
The electric wires of cable bacteria possibly support a unique respiration mode with a few oxygen-reducing cells flaring off electrons, while oxidation of the electron donor and the associated energy conservation and growth is allocated to other cells not exposed to oxygen. Cable bacteria are centimeter-long, multicellular, filamentous Desulfobulbaceae that transport electrons across oxic-anoxic interfaces in aquatic sediments. From observed distortions of the oxic-anoxic interface, we derived oxygen consumption rates of individual cable bacteria and found biomass-specific rates of unheard magnitude in biology. Tightly controlled behavior, possibly involving intercellular electrical signaling, was found to generally keep <10% of individual filaments exposed to oxygen. The results strengthen the hypothesis that cable bacteria indeed have evolved an exceptional way to take the full energetic advantages of aerobic respiration and let >90% of the cells metabolize in the convenient absence of oxidative stress.
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Affiliation(s)
- Stefano Scilipoti
- Center for Electromicrobiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.
| | - Klaus Koren
- Aarhus University Center for Water Technology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Nils Risgaard-Petersen
- Center for Electromicrobiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Andreas Schramm
- Center for Electromicrobiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Lars Peter Nielsen
- Center for Electromicrobiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.
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13
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Makarieva AM, Nefiodov AV, Li BL. Life's Energy and Information: Contrasting Evolution of Volume- versus Surface-Specific Rates of Energy Consumption. ENTROPY (BASEL, SWITZERLAND) 2020; 22:E1025. [PMID: 33286794 PMCID: PMC7597118 DOI: 10.3390/e22091025] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 12/02/2022]
Abstract
As humanity struggles to find a path to resilience amidst global change vagaries, understanding organizing principles of living systems as the pillar for human existence is rapidly growing in importance. However, finding quantitative definitions for order, complexity, information and functionality of living systems remains a challenge. Here, we review and develop insights into this problem from the concept of the biotic regulation of the environment developed by Victor Gorshkov (1935-2019). Life's extraordinary persistence-despite being a strongly non-equilibrium process-requires a quantum-classical duality: the program of life is written in molecules and thus can be copied without information loss, while life's interaction with its non-equilibrium environment is performed by macroscopic classical objects (living individuals) that age. Life's key energetic parameter, the volume-specific rate of energy consumption, is maintained within universal limits by most life forms. Contrary to previous suggestions, it cannot serve as a proxy for "evolutionary progress". In contrast, ecosystem-level surface-specific energy consumption declines with growing animal body size in stable ecosystems. High consumption by big animals is associated with instability. We suggest that the evolutionary increase in body size may represent a spontaneous loss of information about environmental regulation, a manifestation of life's algorithm ageing as a whole.
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Affiliation(s)
- Anastassia M. Makarieva
- Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
- USDA-China MOST Joint Research Center for AgroEcology and Sustainability, University of California, Riverside, CA 92521-0124, USA
| | - Andrei V. Nefiodov
- Theoretical Physics Division, Petersburg Nuclear Physics Institute, Gatchina 188300, Russia
| | - Bai-Lian Li
- USDA-China MOST Joint Research Center for AgroEcology and Sustainability, University of California, Riverside, CA 92521-0124, USA
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14
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The Natural Selection of Metabolism Explains Curvature in Fossil Body Mass Evolution. Evol Biol 2020. [DOI: 10.1007/s11692-020-09493-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Chiyomaru K, Takemoto K. Revisiting the hypothesis of an energetic barrier to genome complexity between eukaryotes and prokaryotes. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191859. [PMID: 32257343 PMCID: PMC7062059 DOI: 10.1098/rsos.191859] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/21/2020] [Indexed: 05/06/2023]
Abstract
The absence of genome complexity in prokaryotes, being the evolutionary precursors to eukaryotic cells comprising all complex life (the prokaryote-eukaryote divide), is a long-standing question in evolutionary biology. A previous study hypothesized that the divide exists because prokaryotic genome size is constrained by bioenergetics (prokaryotic power per gene or genome being significantly lower than eukaryotic ones). However, this hypothesis was evaluated using a relatively small dataset due to lack of data availability at the time, and is therefore controversial. Accordingly, we constructed a larger dataset of genomes, metabolic rates, cell sizes and ploidy levels to investigate whether an energetic barrier to genome complexity exists between eukaryotes and prokaryotes while statistically controlling for the confounding effects of cell size and phylogenetic signals. Notably, we showed that the differences in bioenergetics between prokaryotes and eukaryotes were less significant than those previously reported. More importantly, we found a limited contribution of power per genome and power per gene to the prokaryote-eukaryote dichotomy. Our findings indicate that the prokaryote-eukaryote divide is hard to explain from the energetic perspective. However, our findings may not entirely discount the traditional hypothesis; in contrast, they indicate the need for more careful examination.
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16
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Cartwright JHE, Russell MJ. The origin of life: the submarine alkaline vent theory at 30. Interface Focus 2019; 9:20190104. [PMCID: PMC6802131 DOI: 10.1098/rsfs.2019.0104] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 09/12/2019] [Indexed: 11/12/2023] Open
Affiliation(s)
- Julyan H. E. Cartwright
- Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, 18100 Armilla, Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, 18071 Granada, Spain
| | - Michael J. Russell
- NASA Astrobiology Institute, NASA Ames Research Center California, CA, USA
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17
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Abstract
Scaling laws relating body mass to species characteristics are among the most universal quantitative patterns in biology. Within major taxonomic groups, the 4 key ecological variables of metabolism, abundance, growth, and mortality are often well described by power laws with exponents near 3/4 or related to that value, a commonality often attributed to biophysical constraints on metabolism. However, metabolic scaling theories remain widely debated, and the links among the 4 variables have never been formally tested across the full domain of eukaryote life, to which prevailing theory applies. Here we present datasets of unprecedented scope to examine these 4 scaling laws across all eukaryotes and link them to test whether their combinations support theoretical expectations. We find that metabolism and abundance scale with body size in a remarkably reciprocal fashion, with exponents near ±3/4 within groups, as expected from metabolic theory, but with exponents near ±1 across all groups. This reciprocal scaling supports "energetic equivalence" across eukaryotes, which hypothesizes that the partitioning of energy in space across species does not vary significantly with body size. In contrast, growth and mortality rates scale similarly both within and across groups, with exponents of ±1/4. These findings are inconsistent with a metabolic basis for growth and mortality scaling across eukaryotes. We propose that rather than limiting growth, metabolism adjusts to the needs of growth within major groups, and that growth dynamics may offer a viable theoretical basis to biological scaling.
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18
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Popovic M. Thermodynamic properties of microorganisms: determination and analysis of enthalpy, entropy, and Gibbs free energy of biomass, cells and colonies of 32 microorganism species. Heliyon 2019; 5:e01950. [PMID: 31286084 PMCID: PMC6587057 DOI: 10.1016/j.heliyon.2019.e01950] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/24/2019] [Accepted: 06/07/2019] [Indexed: 11/12/2022] Open
Abstract
Thermodynamic analysis is an important part of chemical engineering. However, its application in biotechnology has been hampered by lack of data on thermodynamic properties of microorganism biomass. In this paper, a review was made of methods for estimation of thermodynamic properties of biomass, including standard enthalpy of combustion hC⁰, enthalpy of formation hf⁰, entropy s⁰, and Gibbs free energy of formation gf⁰. These parameters were calculated on molar and mass specific basis for 32 microorganism species, including 14 bacteria, 7 yeast and 11 algae species. It was found that hf⁰, s⁰, gf⁰ are, respectively, similar for all the analyzed species, due to the fact that all living organisms have a common ancestor and thus a similar chemical composition. Furthermore, all the analyzed microorganisms have negative hf⁰, originating from partial oxidation of all other elements by oxygen and nitrogen. A brief review was given of microorganism endogenous and growth metabolic rates. Finally, based on the determined thermodynamic properties, entropy of individual E. coli and Pseudomonas cells were determined and entropy of a Pseudomonas colony during its lifespan was calculated and analyzed. Three periods can be distinguished in the existence of a microorganism colony: (a) accumulation period when cell number, mass and entropy increase, (b) steady state period when they are approximately constant, and (c) decumulation period when they decrease.
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Affiliation(s)
- Marko Popovic
- Biothermodynamics, TUM School of Life Sciences Weihenstephan, Technical University of Munich, Maximus-von-Imhof-Forum 2, 85354, Freising, Germany
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19
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Lusk BG. Thermophiles; or, the Modern Prometheus: The Importance of Extreme Microorganisms for Understanding and Applying Extracellular Electron Transfer. Front Microbiol 2019; 10:818. [PMID: 31080440 PMCID: PMC6497744 DOI: 10.3389/fmicb.2019.00818] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/01/2019] [Indexed: 11/30/2022] Open
Abstract
Approximately four billion years ago, the first microorganisms to thrive on earth were anaerobic chemoautotrophic thermophiles, a specific group of extremophiles that survive and operate at temperatures ∼50 – 125°C and do not use molecular oxygen (O2) for respiration. Instead, these microorganisms performed respiration via dissimilatory metal reduction by transferring their electrons extracellularly to insoluble electron acceptors. Genetic evidence suggests that Gram-positive thermophilic bacteria capable of extracellular electron transfer (EET) are positioned close to the root of the Bacteria kingdom on the tree of life. On the contrary, EET in Gram-negative mesophilic bacteria is a relatively new phenomenon that is evolutionarily distinct from Gram-positive bacteria. This suggests that EET evolved separately in Gram-positive thermophiles and Gram-negative mesophiles, and that EET in these bacterial types is a result of a convergent evolutionary process leading to homoplasy. Thus, the study of dissimilatory metal reducing thermophiles provides a glimpse into some of Earth’s earliest forms of respiration. This will provide new insights for understanding biogeochemistry and the development of early Earth in addition to providing unique avenues for exploration and discovery in astrobiology. Lastly, the physiological composition of Gram-positive thermophiles, coupled with the kinetic and thermodynamic consequences of surviving at elevated temperatures, makes them ideal candidates for developing new mathematical models and designing innovative next-generation biotechnologies. KEY CONCEPTS Anaerobe: organism that does not require oxygen for growth. Chemoautotroph: organism that obtains energy by oxidizing inorganic electron donors. Convergent Evolution: process in which organisms which are not closely related independently evolve similar traits due to adapting to similar ecological niches and/or environments. Dissimilatory Metal Reduction: reduction of a metal or metalloid that uses electrons from oxidized organic or inorganic electron donors. Exoelectrogen: microorganism that performs dissimilatory metal reduction via extracellular electron transfer. Extremophiles: organisms that thrive in physical or geochemical conditions that are considered detrimental to most life on Earth. Homoplasy: a character shared by a set of species that is not shared by a common ancestor Non-synonymous Substitutions (Ka): a substitution of a nucleotide that changes a codon sequence resulting in a change in the amino acid sequence of a protein. Synonymous Substitutions (Ks): a substitution of a nucleotide that may change a codon sequence, but results in no change in the amino acid sequence of a protein. Thermophiles: a specific group of extremophiles that survive and operate at temperatures ∼50–125°C.
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20
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Li L, Wang G. Enzymatic origin and various curvatures of metabolic scaling in microbes. Sci Rep 2019; 9:4082. [PMID: 30858543 PMCID: PMC6411939 DOI: 10.1038/s41598-019-40712-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 02/22/2019] [Indexed: 11/11/2022] Open
Abstract
The famous and controversial power law is a basal metabolic scaling model mainly derived from the “surface rule” or a fractal transport network. However, this law neglects biological mechanisms in the important active state. Here, we hypothesized that the relative metabolic rate and growth rate of actively growing microbes are driven by the changeable rate of their rate-limiting enzymes and concluded that natural logarithmic microbial metabolism (lnλ) and growth (or biomass) (lnM) are both dependent on limiting resources, and then developed novel models with interdependence between lnλ and lnM. We tested the models using the data obtained from the literature. We explain how and why the scaling is usually curved with the difference between microbial metabolic and growth (or biomass’s) half-saturation constants (KM, Kλ) in the active state and agree that the linear relationship of the power law is a particular case under the given condition: KM = Kλ, which means that the enzyme dynamics may drive active and basal metabolic scaling relationships. Our interdependent model is more general than the power law, which is important for integrating the ecology and biochemical processes.
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Affiliation(s)
- Liyan Li
- College of Life Sciences, Zhejiang University, Hangzhou, China.
| | - Genxuan Wang
- College of Life Sciences, Zhejiang University, Hangzhou, China.
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21
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Affiliation(s)
- Pierre Quévreux
- Sorbonne Universités, Sorbonne Paris Cité, Paris Diderot Univ Paris 07, CNRS, INRA, IRD, UPEC, Inst. d'Écologie et des Sciences de l'Environnement - Paris, iEES-Paris, 4 place Jussieu; FR-75252 Paris France
| | - Ulrich Brose
- EcoNetLab, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Leipzig Germany
- Inst. of Biodiversity, Friedrich Schiller Univ. Jena; Jena Germany
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22
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Johnston ASA, Sibly RM. The influence of soil communities on the temperature sensitivity of soil respiration. Nat Ecol Evol 2018; 2:1597-1602. [PMID: 30150743 DOI: 10.1038/s41559-018-0648-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/26/2018] [Indexed: 11/09/2022]
Abstract
Soil respiration represents a major carbon flux between terrestrial ecosystems and the atmosphere, and is expected to accelerate under climate warming. Despite its importance in climate change forecasts, however, our understanding of the effects of temperature on soil respiration (RS) is incomplete. Using a metabolic ecology approach we link soil biota metabolism, community composition and heterotrophic activity to predict RS rates across five biomes. We find that accounting for the ecological mechanisms underpinning decomposition processes predicts climatological RS variations observed in an independent dataset (n = 312). The importance of community composition is evident because without it RS is substantially underestimated. With increasing temperature, we predict a latitudinal increase in RS temperature sensitivity, with Q10 values ranging between 2.33 ± 0.01 in tropical forests to 2.72 ± 0.03 in tundra. This global trend has been widely observed, but has not previously been linked to soil communities.
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Affiliation(s)
| | - Richard M Sibly
- School of Biological Sciences, University of Reading, Reading, UK
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23
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Russell MJ. Green Rust: The Simple Organizing 'Seed' of All Life? Life (Basel) 2018; 8:E35. [PMID: 30150570 PMCID: PMC6161180 DOI: 10.3390/life8030035] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 06/28/2018] [Accepted: 08/14/2018] [Indexed: 01/18/2023] Open
Abstract
Korenaga and coworkers presented evidence to suggest that the Earth's mantle was dry and water filled the ocean to twice its present volume 4.3 billion years ago. Carbon dioxide was constantly exhaled during the mafic to ultramafic volcanic activity associated with magmatic plumes that produced the thick, dense, and relatively stable oceanic crust. In that setting, two distinct and major types of sub-marine hydrothermal vents were active: ~400 °C acidic springs, whose effluents bore vast quantities of iron into the ocean, and ~120 °C, highly alkaline, and reduced vents exhaling from the cooler, serpentinizing crust some distance from the heads of the plumes. When encountering the alkaline effluents, the iron from the plume head vents precipitated out, forming mounds likely surrounded by voluminous exhalative deposits similar to the banded iron formations known from the Archean. These mounds and the surrounding sediments, comprised micro or nano-crysts of the variable valence FeII/FeIII oxyhydroxide known as green rust. The precipitation of green rust, along with subsidiary iron sulfides and minor concentrations of nickel, cobalt, and molybdenum in the environment at the alkaline springs, may have established both the key bio-syntonic disequilibria and the means to properly make use of them-the elements needed to effect the essential inanimate-to-animate transitions that launched life. Specifically, in the submarine alkaline vent model for the emergence of life, it is first suggested that the redox-flexible green rust micro- and nano-crysts spontaneously precipitated to form barriers to the complete mixing of carbonic ocean and alkaline hydrothermal fluids. These barriers created and maintained steep ionic disequilibria. Second, the hydrous interlayers of green rust acted as engines that were powered by those ionic disequilibria and drove essential endergonic reactions. There, aided by sulfides and trace elements acting as catalytic promoters and electron transfer agents, nitrate could be reduced to ammonia and carbon dioxide to formate, while methane may have been oxidized to methyl and formyl groups. Acetate and higher carboxylic acids could then have been produced from these C1 molecules and aminated to amino acids, and thence oligomerized to offer peptide nests to phosphate and iron sulfides, and secreted to form primitive amyloid-bounded structures, leading conceivably to protocells.
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Affiliation(s)
- Michael J Russell
- Planetary Chemistry and Astrobiology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA.
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24
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Affiliation(s)
- Lars Witting
- Greenland Inst. of Natural Resources; Box 570, DK-3900 Nuuk Greenland Denmark
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25
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Branscomb E, Russell MJ. Frankenstein or a Submarine Alkaline Vent: Who Is Responsible for Abiogenesis?: Part 1: What is life-that it might create itself? Bioessays 2018; 40:e1700179. [PMID: 29870581 DOI: 10.1002/bies.201700179] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 04/16/2018] [Indexed: 12/13/2022]
Abstract
Origin of life models based on "energized assemblages of building blocks" are untenable in principle. This is fundamentally a consequence of the fact that any living system is in a physical state that is extremely far from equilibrium, a condition it must itself build and sustain. This in turn requires that it carries out all of its molecular transformations-obligatorily those that convert, and thereby create, disequilibria-using case-specific mechanochemical macromolecular machines. Mass-action solution chemistry is quite unable to do this. We argue in Part 2 of this series that this inherent dependence of life on disequilibria-converting macromolecular machines is also an obligatory requirement for life at its emergence. Therefore, life must have been launched by the operation of abiotic macromolecular machines driven by abiotic, but specifically "life-like", disequilibria, coopted from mineral precipitates that are chemically and physically active. Models grounded in "chemistry-in-a-bag" ideas, however energized, should not be considered.
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Affiliation(s)
- Elbert Branscomb
- Carl R. Woese Institute for Genomic Biology and Department of Physics, University of Illinois, Urbana, IL, 61801, USA
| | - Michael J Russell
- Planetary Chemistry and Astrobiology, Jet Propulsion Laboratory California Institute of Technology, Pasadena, CA, 91109-8099, USA
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Abstract
PURPOSE OF REVIEW The influence of gut bacteria upon host physiology is increasingly recognized, but mechanistic links are lacking. Diseases of energetic imbalance such as obesity and diabetes represent major risk factors for cardiovascular diseases such as hypertension. Thus, here, we review current mechanistic contributions of the gut microbiota to host energetics. RECENT FINDINGS Gut bacteria generate a multitude of small molecules which can signal to host tissues within and beyond the gastrointestinal tract to influence host physiology, and gut bacteria can also influence host digestive efficiency by altering the bioavailability of polysaccharides, yet the quantitative energetic effects of these processes remain unclear. Recently, our team has demonstrated that gut bacteria constitute a major anaerobic thermogenic biomass, which can quantitatively account for obesity. Quantitative understanding of the mechanisms by which gut bacteria influence energy homeostasis may ultimately inform the relationship between gut bacteria and cardiovascular dysfunction.
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27
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Rediscovering and Reviving Old Observations and Explanations of Metabolic Scaling in Living Systems. SYSTEMS 2018. [DOI: 10.3390/systems6010004] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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28
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Maske H, Cajal-Medrano R, Villegas-Mendoza J. Substrate-Limited and -Unlimited Coastal Microbial Communities Show Different Metabolic Responses with Regard to Temperature. Front Microbiol 2017; 8:2270. [PMID: 29218033 PMCID: PMC5703737 DOI: 10.3389/fmicb.2017.02270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 11/03/2017] [Indexed: 11/29/2022] Open
Abstract
Bacteria are the principal consumers of dissolved organic carbon (DOC) in the ocean and predation of bacteria makes organic carbon available to higher trophic levels. The efficiency with which bacteria convert the consumed carbon (C) into biomass (i.e., carbon growth efficiency, Y) determines their ecological as well as biogeochemical role in marine ecosystems. Yet, it is still unclear how changes in temperature will affect Y and, hence, the transfer of consumed C to higher trophic levels. Here, we experimentally investigated the effect of temperature on metabolic functions of coastal microbial communities inoculated in both nutrient-limited chemostats and nutrient–unlimited turbidostats. We inoculated chemostats and turbidostats with coastal microbial communities into seawater culture medium augmented with 20 and 100 μmol L−1 of glucose respectively and measured CO2 production, carbon biomass and cell abundance. Chemostats were cultured between 14 and 26°C and specific growth rates (μ) between 0.05 and 6.0 day−1, turbidostats were cultured between 10 and 26°C with specific growth rates ranging from 28 to 62 day−1. In chemostats under substrate limitation, which is common in the ocean, the specific respiration rate (r, day−1) showed no trend with temperature and was roughly proportional to μ, implying that carbon growth efficiency (Y) displayed no tendency with temperature. The response was very different in turbidostats under temperature-limited, nutrient-repleted growth, here μ increased with temperature but r decreased resulting in an increase of Y with temperature (Q10: 2.6). Comparison of our results with data from the literature on the respiration rate and cell weight of monospecific bacteria indicates that in general the literature data behaved similar to chemostat data, showing no trend in specific respiration with temperature. We conclude that respiration rates of nutrient-limited bacteria measured at a certain temperature cannot be adjusted to different temperatures with a temperature response function similar to Q10 or Arrhenius. However, the cellular respiration rate and carbon demand rate (both: mol C cell−1 day−1) show statistically significant relations with cellular carbon content (mol C cell−1) in chemostats, turbidostats, and the literature data.
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Affiliation(s)
- Helmut Maske
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Mexico
| | - Ramón Cajal-Medrano
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Mexico.,Facultad de Ciencias Marinas, Universidad Autónoma de Baja California (UABC), Ensenada, Mexico
| | - Josué Villegas-Mendoza
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California (UABC), Ensenada, Mexico
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29
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Witting L. The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals. Ecol Evol 2017; 7:9098-9118. [PMID: 29152201 PMCID: PMC5677505 DOI: 10.1002/ece3.3432] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 06/07/2017] [Indexed: 12/28/2022] Open
Abstract
I show that the natural selection of metabolism and mass can select for the major life‐history and allometric transitions that define lifeforms from viruses, over prokaryotes and larger unicells, to multicellular animals. The proposed selection is driven by a mass‐specific metabolism that is selected as the pace of the resource handling that generates net energy for self‐replication. An initial selection of mass is given by a dependence of mass‐specific metabolism on mass in replicators that are close to a lower size limit. A sublinear maximum dependence selects for virus‐like replicators, with no intrinsic metabolism, no cell, and practically no mass. A superlinear dependence selects for prokaryote‐like self‐replicating cells, with asexual reproduction and incomplete metabolic pathways. These self‐replicators have selection for increased net energy, and this generates a gradual unfolding of population‐dynamic feed‐back selection from interactive competition. The incomplete feed‐back selects for larger unicells with more developed metabolic pathways, and the completely developed feed‐back for multicellular animals with sexual reproduction. This model unifies the natural selection of lifeforms from viruses to multicellular animals, and it provides a parsimonious explanation where allometries and major life histories evolve from the natural selection of metabolism and mass.
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Affiliation(s)
- Lars Witting
- Greenland Institute of Natural Resources Nuuk Greenland
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30
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Witting L. The natural selection of metabolism and mass selects allometric transitions from prokaryotes to mammals. Theor Popul Biol 2017; 117:23-42. [DOI: 10.1016/j.tpb.2017.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 07/31/2017] [Accepted: 08/21/2017] [Indexed: 11/30/2022]
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31
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Applying allometric theory to fungi. ISME JOURNAL 2017; 11:2175-2180. [PMID: 28708128 DOI: 10.1038/ismej.2017.86] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/15/2017] [Accepted: 04/25/2017] [Indexed: 11/08/2022]
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32
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Kempes CP, van Bodegom PM, Wolpert D, Libby E, Amend J, Hoehler T. Drivers of Bacterial Maintenance and Minimal Energy Requirements. Front Microbiol 2017; 8:31. [PMID: 28197128 PMCID: PMC5281582 DOI: 10.3389/fmicb.2017.00031] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 01/05/2017] [Indexed: 11/13/2022] Open
Abstract
Microbes maintain themselves through a variety of processes. Several of these processes can be reduced or shut down entirely when resource availability declines. In pure culture conditions with ample substrate supply, a relationship between the maximum growth rate and the energy invested in maintenance has been reported widely. However, at the other end of the resources spectrum, bacteria are so extremely limited by energy that no growth occurs and metabolism is constrained to the most essential functions only. These minimum energy requirements have been called the basal power requirement. While seemingly different from each other, both aspects are likely components of a continuum of regulated maintenance processes. Here, we analyze cross-species tradeoffs in cellular physiology over the range of bacterial size and energy expenditure and determine the contributions to maintenance metabolism at each point along the size-energy spectrum. Furthermore, by exploring the simplest bacteria within this framework– which are most affected by maintenance constraints– we uncover which processes become most limiting. For the smallest species, maintenance metabolism converges on total metabolism, where we predict that maintenance is dominated by the repair of proteins. For larger species the relative costs of protein repair decrease and maintenance metabolism is predicted to be dominated by the repair of RNA components. These results provide new insights into which processes are likely to be regulated in environments that are extremely limited by energy.
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Affiliation(s)
| | | | | | | | - Jan Amend
- Department of Earth Sciences, University of Southern CaliforniaLos Angeles, CA, USA; Department of Biological Sciences, University of Southern CaliforniaLos Angeles, CA, USA
| | - Tori Hoehler
- NASA Ames Research Center Moffett Field, CA, USA
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33
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Meyer-Vernet N, Rospars JP. Maximum relative speeds of living organisms: Why do bacteria perform as fast as ostriches? Phys Biol 2016; 13:066006. [DOI: 10.1088/1478-3975/13/6/066006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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34
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García FC, García-Martín EE, Taboada FG, Sal S, Serret P, López-Urrutia Á. The allometry of the smallest: superlinear scaling of microbial metabolic rates in the Atlantic Ocean. ISME JOURNAL 2015; 10:1029-36. [PMID: 26636550 PMCID: PMC5029206 DOI: 10.1038/ismej.2015.203] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/27/2015] [Accepted: 10/04/2015] [Indexed: 11/24/2022]
Abstract
Prokaryotic planktonic organisms are small in size but largely relevant in marine biogeochemical cycles. Due to their reduced size range (0.2 to 1 μm in diameter), the effects of cell size on their metabolism have been hardly considered and are usually not examined in field studies. Here, we show the results of size-fractionated experiments of marine microbial respiration rate along a latitudinal transect in the Atlantic Ocean. The scaling exponents obtained from the power relationship between respiration rate and size were significantly higher than one. This superlinearity was ubiquitous across the latitudinal transect but its value was not universal revealing a strong albeit heterogeneous effect of cell size on microbial metabolism. Our results suggest that the latitudinal differences observed are the combined result of changes in cell size and composition between functional groups within prokaryotes. Communities where the largest size fraction was dominated by prokaryotic cyanobacteria, especially Prochlorococcus, have lower allometric exponents. We hypothesize that these larger, more complex prokaryotes fall close to the evolutionary transition between prokaryotes and protists, in a range where surface area starts to constrain metabolism and, hence, are expected to follow a scaling closer to linearity.
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Affiliation(s)
- Francisca C García
- Centro Oceanográfico de Gijón, Instituto Español de Oceanografía, Gijón, Spain
| | - Enma Elena García-Martín
- Universidad de Vigo, Departamento de Ecología y Biología Animal, Carretera Colegio Universitario, Vigo, Spain
| | | | - Sofía Sal
- Centro Oceanográfico de Gijón, Instituto Español de Oceanografía, Gijón, Spain
| | - Pablo Serret
- Universidad de Vigo, Departamento de Ecología y Biología Animal, Carretera Colegio Universitario, Vigo, Spain.,Estación de Ciencias Marinas de Toralla, Universidad de Vigo, Toralla Island, Vigo, Spain
| | - Ángel López-Urrutia
- Centro Oceanográfico de Gijón, Instituto Español de Oceanografía, Gijón, Spain
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35
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Abstract
A microbe's growth rate helps to set its ecological success and its contribution to food web dynamics and biogeochemical processes. Growth rates at the community level are constrained by biomass and trophic interactions among bacteria, phytoplankton, and their grazers. Phytoplankton growth rates are approximately 1 d(-1), whereas most heterotrophic bacteria grow slowly, close to 0.1 d(-1); only a few taxa can grow ten times as fast. Data from 16S rRNA and other approaches are used to speculate about the growth rate and the life history strategy of SAR11, the most abundant clade of heterotrophic bacteria in the oceans. These strategies are also explored using genomic data. Although the methods and data are imperfect, the available data can be used to set limits on growth rates and thus on the timescale for changes in the composition and structure of microbial communities.
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Affiliation(s)
- David L Kirchman
- School of Marine Science and Policy, University of Delaware, Lewes, Delaware 19958;
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36
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Beratan DN, Liu C, Migliore A, Polizzi NF, Skourtis SS, Zhang P, Zhang Y. Charge transfer in dynamical biosystems, or the treachery of (static) images. Acc Chem Res 2015; 48:474-81. [PMID: 25307316 PMCID: PMC4333612 DOI: 10.1021/ar500271d] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
The image is not the thing. Just as a pipe rendered
in an oil painting cannot be smoked, quantum mechanical coupling pathways
rendered on LCDs do not convey electrons. The aim of this Account
is to examine some of our recent discoveries regarding biological
electron transfer (ET) and transport mechanisms that emerge when one
moves beyond treacherous static views to dynamical frameworks. Studies over the last two decades introduced both atomistic detail
and macromolecule dynamics to the description of biological ET. The
first model to move beyond the structureless square-barrier tunneling
description is the Pathway model, which predicts how protein secondary
motifs and folding-induced through-bond and through-space tunneling
gaps influence kinetics. Explicit electronic structure theory is applied
routinely now to elucidate ET mechanisms, to capture pathway interferences,
and to treat redox cofactor electronic structure effects. Importantly,
structural sampling of proteins provides an understanding of how dynamics
may change the mechanisms of biological ET, as ET rates are exponentially
sensitive to structure. Does protein motion average out tunneling
pathways? Do conformational fluctuations gate biological ET? Are transient
multistate resonances produced by energy gap fluctuations? These questions
are becoming accessible as the static view of biological ET recedes
and dynamical viewpoints take center stage. This Account introduces
ET reactions at the core of bioenergetics, summarizes our team’s
progress toward arriving at an atomistic-level description, examines
how thermal fluctuations influence ET, presents metrics that characterize
dynamical effects on ET, and discusses applications in very long (micrometer
scale) bacterial nanowires. The persistence of structural effects
on the ET rates in the face of thermal fluctuations is considered.
Finally, the flickering resonance (FR) view of charge transfer is
presented to examine how fluctuations control low-barrier transport
among multiple groups in van der Waals contact. FR produces exponential
distance dependence in the absence of tunneling; the exponential character
emerges from the probability of matching multiple vibronically broadened
electronic energies within a tolerance defined by the rms coupling
among interacting groups. FR thus produces band like coherent transport
on the nanometer length scale, enabled by conformational fluctuations.
Taken as a whole, the emerging context for ET in dynamical biomolecules
provides a robust framework to design and interpret the inner workings
of bioenergetics from the molecular to the cellular scale and beyond,
with applications in biomedicine, biocatalysis, and energy science.
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Shibata K, Amemiya T, Itoh K. Effects of oxytetracycline on populations and community metabolism of an aquatic microcosm. Ecol Res 2014. [DOI: 10.1007/s11284-014-1128-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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39
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Succession of cable bacteria and electric currents in marine sediment. ISME JOURNAL 2014; 8:1314-22. [PMID: 24451206 DOI: 10.1038/ismej.2013.239] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/12/2013] [Accepted: 12/04/2013] [Indexed: 11/08/2022]
Abstract
Filamentous Desulfobulbaceae have been reported to conduct electrons over centimetre-long distances, thereby coupling oxygen reduction at the surface of marine sediment to sulphide oxidation in sub-surface layers. To understand how these 'cable bacteria' establish and sustain electric conductivity, we followed a population for 53 days after exposing sulphidic sediment with initially no detectable filaments to oxygen. After 10 days, cable bacteria and electric currents were established throughout the top 15 mm of the sediment, and after 21 days the filament density peaked with a total length of 2 km cm(-2). Cells elongated and divided at all depths with doubling times over the first 10 days of <20 h. Active, oriented movement must have occurred to explain the separation of O2 and H2S by 15 mm. Filament diameters varied from 0.4-1.7 μm, with a general increase over time and depth, and yet they shared 16S rRNA sequence identity of >98%. Comparison of the increase in biovolume and electric current density suggested high cellular growth efficiency. While the vertical expansion of filaments continued over time and reached 30 mm, the electric current density and biomass declined after 13 and 21 days, respectively. This might reflect a breakdown of short filaments as their solid sulphide sources became depleted in the top layers of the anoxic zone. In conclusion, cable bacteria combine rapid and efficient growth with oriented movement to establish and exploit the spatially separated half-reactions of sulphide oxidation and oxygen consumption.
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Oxygen consumption rates of bacteria under nutrient-limited conditions. Appl Environ Microbiol 2013; 79:4921-31. [PMID: 23770901 DOI: 10.1128/aem.00756-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many environments on Earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. To better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. The oxygen consumption and population density of batch cultures of Escherichia coli K-12, Shewanella oneidensis MR-1, and Marinobacter aquaeolei VT8 were tracked for up to 200 days. The oxygen consumption per CFU (QO2) declined by more than 2 orders of magnitude for all three strains as they transitioned from nutrient-abundant log-phase growth to the nutrient-limited early stationary phase. The large reduction in QO2 from growth to stationary phase suggests that nutrient availability is an important factor in considering environmental respiration rates. Following the death phase, during the long-term stationary phase (LTSP), QO2 values of the surviving population increased with time and more cells were respiring than formed colonies. Within the respiring population, a subpopulation of highly respiring cells increased in abundance with time. Apparently, as cells enter LTSP, there is a viable but not culturable population whose bulk community and per cell respiration rates are dynamic. This result has a bearing on how minimal energy requirements are met, especially in nutrient-limited environments. The minimal QO2 rates support the extension of Kleiber's law to the mass of a bacterium (100-fg range).
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Abstract
A great number of the bacteria and archaea on Earth are found in subsurface environments in a physiological state that is poorly represented or explained by laboratory cultures. Microbial cells in these very stable and oligotrophic settings catabolize 10⁴- to 10⁶-fold more slowly than model organisms in nutrient-rich cultures, turn over biomass on timescales of centuries to millennia rather than hours to days, and subsist with energy fluxes that are 1,000-fold lower than the typical culture-based estimates of maintenance requirements. To reconcile this disparate state of being with our knowledge of microbial physiology will require a revised understanding of microbial energy requirements, including identifying the factors that comprise true basal maintenance and the adaptations that might serve to minimize these factors.
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Buchholz F, Lerchner J, Mariana F, Kuhlicke U, Neu TR, Harms H, Maskow T. Chip-calorimetry provides real time insights into the inactivation of biofilms by predatory bacteria. BIOFOULING 2012; 28:351-362. [PMID: 22509741 DOI: 10.1080/08927014.2012.673593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Control or removal of undesired biofilms has frequently been found to be quite difficult. In addition to biocidal or antibiotic chemicals or materials designed to prevent biofouling, biological control agents appear to be promising. Reports of bacterial predators eradicating biofilms or eliminating pathogens motivate a more systematic screening of biofilm-eliminating bacterial predators. Unfortunately, the analysis of the eradication process is demanding. In the present study, chip-calorimetry was applied to monitor the elimination of Pseudomonas sp. biofilms by Bdellovibrio bacteriovorus. The method uses metabolic heat as a real-time parameter for biofilm activity. The method is non-invasive, fast and convenient due to real-time data acquisition. In addition, heat-production data can reveal information about the energetics of the predator-prey interaction. The calorimetric results were validated by confocal laser scanning microscopy. The approach described may be useful for the screening of biofilm susceptibility to different predators.
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Affiliation(s)
- F Buchholz
- Department of Environmental Microbiology, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany
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Lane N. Energetics and genetics across the prokaryote-eukaryote divide. Biol Direct 2011; 6:35. [PMID: 21714941 PMCID: PMC3152533 DOI: 10.1186/1745-6150-6-35] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Accepted: 06/30/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND All complex life on Earth is eukaryotic. All eukaryotic cells share a common ancestor that arose just once in four billion years of evolution. Prokaryotes show no tendency to evolve greater morphological complexity, despite their metabolic virtuosity. Here I argue that the eukaryotic cell originated in a unique prokaryotic endosymbiosis, a singular event that transformed the selection pressures acting on both host and endosymbiont. RESULTS The reductive evolution and specialisation of endosymbionts to mitochondria resulted in an extreme genomic asymmetry, in which the residual mitochondrial genomes enabled the expansion of bioenergetic membranes over several orders of magnitude, overcoming the energetic constraints on prokaryotic genome size, and permitting the host cell genome to expand (in principle) over 200,000-fold. This energetic transformation was permissive, not prescriptive; I suggest that the actual increase in early eukaryotic genome size was driven by a heavy early bombardment of genes and introns from the endosymbiont to the host cell, producing a high mutation rate. Unlike prokaryotes, with lower mutation rates and heavy selection pressure to lose genes, early eukaryotes without genome-size limitations could mask mutations by cell fusion and genome duplication, as in allopolyploidy, giving rise to a proto-sexual cell cycle. The side effect was that a large number of shared eukaryotic basal traits accumulated in the same population, a sexual eukaryotic common ancestor, radically different to any known prokaryote. CONCLUSIONS The combination of massive bioenergetic expansion, release from genome-size constraints, and high mutation rate favoured a protosexual cell cycle and the accumulation of eukaryotic traits. These factors explain the unique origin of eukaryotes, the absence of true evolutionary intermediates, and the evolution of sex in eukaryotes but not prokaryotes. REVIEWERS This article was reviewed by: Eugene Koonin, William Martin, Ford Doolittle and Mark van der Giezen. For complete reports see the Reviewers' Comments section.
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Affiliation(s)
- Nick Lane
- Department of Genetics, Evolution and Environment, University College London, London, UK.
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Abstract
During the 13 years since it was first advanced, the fractal network theory (FNT), an analytic theory of allometric scaling, has been subjected to a wide range of methodological, mathematical and empirical criticisms, not all of which have been answered satisfactorily. FNT presumes a two-variable power-law relationship between metabolic rate and body mass. This assumption has been widely accepted in the past, but a growing body of evidence during the past quarter century has raised questions about its general validity. There is now a need for alternative theories of metabolic scaling that are consistent with empirical observations over a broad range of biological applications. In this article, we briefly review the limitations of FNT, examine the evidence that the two-variable power-law assumption is invalid, and outline alternative perspectives. In particular, we discuss quantum metabolism (QM), an analytic theory based on molecular-cellular processes. QM predicts the large variations in scaling exponent that are found empirically and also predicts the temperature dependence of the proportionality constant, issues that have eluded models such as FNT that are based on macroscopic and network properties of organisms.
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Affiliation(s)
- Paul S Agutter
- Theoretical Medicine and Biology Group, 26 Castle Hill, Glossop, Derbyshire SK13 7RR, UK.
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Unanticipated consequences of logarithmic transformation in bivariate allometry. J Comp Physiol B 2011; 181:841-9. [DOI: 10.1007/s00360-011-0565-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 02/14/2011] [Accepted: 02/23/2011] [Indexed: 10/18/2022]
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Kaiyala KJ, Ramsay DS. Direct animal calorimetry, the underused gold standard for quantifying the fire of life. Comp Biochem Physiol A Mol Integr Physiol 2011; 158:252-64. [PMID: 20427023 PMCID: PMC3920988 DOI: 10.1016/j.cbpa.2010.04.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 04/16/2010] [Accepted: 04/18/2010] [Indexed: 11/25/2022]
Abstract
Direct animal calorimetry, the gold standard method for quantifying animal heat production (HP), has been largely supplanted by respirometric indirect calorimetry owing to the relative ease and ready commercial availability of the latter technique. Direct calorimetry, however, can accurately quantify HP and thus metabolic rate (MR) in both metabolically normal and abnormal states, whereas respirometric indirect calorimetry relies on important assumptions that apparently have never been tested in animals with genetic or pharmacologically-induced alterations that dysregulate metabolic fuel partitioning and storage so as to promote obesity and/or diabetes. Contemporary obesity and diabetes research relies heavily on metabolically abnormal animals. Recent data implicating individual and group variation in the gut microbiome in obesity and diabetes raise important questions about transforming aerobic gas exchange into HP because 99% of gut bacteria are anaerobic and they outnumber eukaryotic cells in the body by ∼10-fold. Recent credible work in non-standard laboratory animals documents substantial errors in respirometry-based estimates of HP. Accordingly, it seems obvious that new research employing simultaneous direct and indirect calorimetry (total calorimetry) will be essential to validate respirometric MR phenotyping in existing and future pharmacological and genetic models of obesity and diabetes. We also detail the use of total calorimetry with simultaneous core temperature assessment as a model for studying homeostatic control in a variety of experimental situations, including acute and chronic drug administration. Finally, we offer some tips on performing direct calorimetry, both singly and in combination with indirect calorimetry and core temperature assessment.
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Affiliation(s)
- Karl J Kaiyala
- University of Washington, Department of Dental Public Health Sciences, School of Dentistry, Seattle, WA 98195-7475, USA.
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Kaiyala KJ, Schwartz MW. Toward a more complete (and less controversial) understanding of energy expenditure and its role in obesity pathogenesis. Diabetes 2011; 60:17-23. [PMID: 21193735 PMCID: PMC3012169 DOI: 10.2337/db10-0909] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Karl J Kaiyala
- Department of Dental Public Health Sciences, University of Washington, Seattle, USA.
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Abstract
All complex life is composed of eukaryotic (nucleated) cells. The eukaryotic cell arose from prokaryotes just once in four billion years, and otherwise prokaryotes show no tendency to evolve greater complexity. Why not? Prokaryotic genome size is constrained by bioenergetics. The endosymbiosis that gave rise to mitochondria restructured the distribution of DNA in relation to bioenergetic membranes, permitting a remarkable 200,000-fold expansion in the number of genes expressed. This vast leap in genomic capacity was strictly dependent on mitochondrial power, and prerequisite to eukaryote complexity: the key innovation en route to multicellular life.
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Affiliation(s)
- Nick Lane
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London W1E 6BT, UK.
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Giesing ER, Suski CD, Warner RE, Bell AM. Female sticklebacks transfer information via eggs: effects of maternal experience with predators on offspring. Proc Biol Sci 2010; 278:1753-9. [PMID: 21068041 DOI: 10.1098/rspb.2010.1819] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
There is growing evidence that maternal experience influences offspring via non-genetic mechanisms. When female three-spined sticklebacks (Gasterosteus aculeatus) were exposed to the threat of predation, they produced larger eggs with higher cortisol content, which consumed more oxygen shortly after fertilization compared with a control group. As juveniles, the offspring of predator-exposed mothers exhibited tighter shoaling behaviour, an antipredator defence. We did not detect an effect of maternal exposure to predation risk on the somatic growth of fry. Altogether, we found that exposure to an ecologically relevant stressor during egg formation had several long-lasting consequences for offspring, some of which might be mediated by exposure to maternally derived cortisol. These results support the hypothesis that female sticklebacks might influence the development, growth and behaviour of their offspring via eggs to match their future environment.
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Affiliation(s)
- Eric R Giesing
- Natural Resources and Environmental Sciences, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA
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DeLong JP, Okie JG, Moses ME, Sibly RM, Brown JH. Shifts in metabolic scaling, production, and efficiency across major evolutionary transitions of life. Proc Natl Acad Sci U S A 2010; 107:12941-5. [PMID: 20616006 PMCID: PMC2919978 DOI: 10.1073/pnas.1007783107] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The diversification of life involved enormous increases in size and complexity. The evolutionary transitions from prokaryotes to unicellular eukaryotes to metazoans were accompanied by major innovations in metabolic design. Here we show that the scalings of metabolic rate, population growth rate, and production efficiency with body size have changed across the evolutionary transitions. Metabolic rate scales with body mass superlinearly in prokaryotes, linearly in protists, and sublinearly in metazoans, so Kleiber's 3/4 power scaling law does not apply universally across organisms. The scaling of maximum population growth rate shifts from positive in prokaryotes to negative in protists and metazoans, and the efficiency of production declines across these groups. Major changes in metabolic processes during the early evolution of life overcame existing constraints, exploited new opportunities, and imposed new constraints.
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Affiliation(s)
- John P. DeLong
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520
| | - Jordan G. Okie
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
| | - Melanie E. Moses
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
- Department of Computer Science, University of New Mexico, Albuquerque, NM 87131
| | - Richard M. Sibly
- School of Biological Sciences, University of Reading, Reading RG6 6AS, United Kingdom; and
| | - James H. Brown
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
- Santa Fe Institute, Santa Fe, NM 87501
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