Evolution of Anaerobic Energy Metabolism-Free-Samples for Students

Question: Discuss about the Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes. Answer: Introduction Information on whether mitochondria are present and function in eukaryotes living in anaerobic environments has been unclear(Hjort, Goldberg, Tsaousis, Hirt, Embley, 2010). However, documented research into the phylogenetic distribution, biochemistry, and evolutionary importance of organelles participating in the formation of ATP in eukaryotes which inhabit those conditions continues to increase in volume(Gawryluk, Kamikawa, Stairs, Silberman, Brown, Roger, 2016). Anaerobic mitochondria function anaerobically and use compounds beside oxygen as the final electron acceptor(Mller, et al., 2012). The advances in the research have led to the conclusion that eukaryotic groups have an organelle with an origin unique to mitochondria, which has reproduced the origin of mitochondria to that of established eukaryotic groups(Mller, et al., 2012). The phylogeny of eukaryotic aerobes and anaerobes also interleaves around the eukaryotic groups diversity thereby disproving the belief that there ex ists a distinction between eukaryotic aerobes and their anaerobic counterparts(Mller, et al., 2012). Experimentation The article selected documented research that has been previously done on the topic and links the findings to an updated phylogenetic framework. This is done to give a comparative picture that highlights the uniformity among mitochondrial energy metabolic pathways that are not dependent on oxygen among the many eukaryotic lineages without blurring any distinctions(Makiuchi Nozaki, 2014). Therefore, findings on topics such as energy metabolism in anaerobic protists, hydrogenosomes, anaerobic mitochondria, Giardia intestinalis, Entamoeba histolytica, Trichomonas vaginalis and Tritrichomonas foetus were covered(Mller, et al., 2012). The function of mitochondria in parasites was gathered from various articles and reference materials. Results and Discussion Since the article was based on a review of previous research conducted in the field of anaerobic metabolism of eukaryotes, the findings presented comprised of systematic summaries of relevant knowledge. The information presented discussed the energy metabolism in anaerobic protists, hydrogenosomes, anaerobic mitochondria, Giardia intestinalis, Entamoeba histolytica, Trichomonas vaginalis and Tritrichomonas foetus, and function of mitochondria in parasites(Mller, et al., 2012). Article Critique The authors reviewed current biochemical information on enzymes and pathways taken by eukaryotes during anaerobic metabolism and identified the products that are generated in the anaerobic habitats (Mller, et al., 2012). Special attention was paid to the biochemical roles that the mitochondria in these organisms play in the anaerobic synthesis of ATP. The paper presents the metabolic maps of compartmentalized energy metabolism from 16 organisms (Mller, et al., 2012). However, the research does not report on any enzyme specialized in anaerobic metabolism, which are unique to any of the known six lineages of eukaryotes since genes found in a group are also present in another group (Mller, et al., 2012). This review was aimed at surveying the energy metabolism, particularly that of mitochondria in anaerobic eukaryotes in their life cycles. The study also focused on organisms such as metazoans, from which adequate biochemical information exists on the primary enzyme function, and the products excreted to facilitate the presentation of the metabolic maps (Mller, et al., 2012). The review covered protists and metazoans but did not consider metazoans capable of withstanding temporary hypoxia or anoxia in lactate, ethanol, and other fermentations (Mller, et al., 2012). The review centered on metabolic pathways specific to anaerobic eukaryotes and their mitochondria. The authors linked various research findings to create their review and offer an update of the phylogenetic framework. Definitions of various phenomena and processes have also been edited to fit the objectives of the paper. For example, eukaryotes in the paper refer to heterotrophs or growth of that nature because the authors did not consider photosynthetic synthesis of ATP in the paper. Therefore, the chief synthesis of ATP in eukaryotes was determined to be the oxidation of already reduced carbon compounds(Stairs, Leger, Roger, 2015). The eukaryotes considered in the paper were also those that lived in fully oxic environments and do not use oxygen for oxidative phosphorylation. Even in oxygen, such organisms are able to use it as a terminal acceptor or ignore it(Thiergart, Landan, Marc Schenk, 2012). In some sections of the paper, eukaryotes that do not require oxygen in their core energy metabolism were referred to as being anaerobic. The various definitions of similar or identical components open the paper for lots of interpretations and increases the chances of confusion. The definitions could be said to have been used discriminately to only serve the objectives of the writers. The metabolic pathways in eukaryote anaerobes section was extensive and thorough. The information was presented systematically and easy to follow the train of thought from one section to the next. The focus was drawn towards the major metabolic pathways and the key end products. This implies that the intermediary products were not considered and would thus require someone reading the paper to be familiar with the processes or products to follow the processes. Many of the organisms covered in the paper had life cycles that had huge stage-defined differences in their energy metabolism. Presentation of the pathways in a phylogenetic approach based on the six super groups limited the amount of information presented. For example, the functional information concerning loriciferan organelles was not provided same as the lineages that did not have organelles of mitochondrial origin(Esposti, Cortez, Lozano, Rasmussen, Nielsen, Romero, 2016). The implication on research is that more information needs to be provided in future studies to control or correct for new information from research(Leger, Gawryluk, Gray, Roger, 2013). As noted by the authors, previous research had presented the flow of electrons from NAD(P)H to H2 in one of the figures was inaccurate because it was not favorable energetically and not likely to be correct(Hug, Stechmann, Roger, 2010). Conclusion Extensive research has only managed to uncover similar basic sets of genes and enzymes involved in anaerobic metabolism of energy among the known primary lineages. There is unity in eukaryotic anaerobic energy metabolism in the main ancestries alluding to one origin and common ancestry. The advances in the research have led to the conclusion that eukaryotic groups have an organelle with an origin unique to mitochondria, which has reproduced the source of mitochondria to that of established groups of eukaryotes. The authors reviewed documented biochemical information on enzymes and pathways taken by eukaryotes during anaerobic metabolism and identified the products that are generated in the anaerobic habitats. The review covered protists and metazoans and not metazoans capable of withstanding short-term hypoxia or anoxia in ethanol, lactate, and other fermentations. References Esposti, M. D., Cortez, D., Lozano, L., Rasmussen, S., Nielsen, H. B., Romero, E. M. (2016). Alpha proteobacterial ancestry of the [Fe-Fe]-hydrogenases in anaerobic eukaryotes. Biology Direct, 11:34. Gawryluk, R., Kamikawa, R., Stairs, C., Silberman, J., Brown, M., Roger, A. (2016). The Earliest Stages of Mitochondrial Adaptation to Low Oxygen Revealed in a Novel Rhizarian. Current Biology, 26(20), 2729-2738. Hjort, K., Goldberg, A. V., Tsaousis, A. D., Hirt, R. P., Embley, M. (2010). Diversity and reductive evolution of mitochondria among microbial eukaryotes. Philosophical Transactions of the Royal Society of Biology, DOI: 10.1098/rstb.2009.0224. Hug, L. A., Stechmann, A., Roger, A. J. (2010). Phylogenetic Distributions and Histories of Proteins Involved in Anaerobic Pyruvate Metabolism in Eukaryotes. Molecular Biology and Evolution, 27(2), 311-324. Leger, M. M., Gawryluk, R. M., Gray, M. W., Roger, A. J. (2013). Evidence for a Hydrogenosomal-Type Anaerobic ATP Generation Pathway in Acanthamoeba castellanii. PLOS ONE, https://doi.org/10.1371/journal.pone.0069532. Makiuchi, T., Nozaki, T. (2014). Highly divergent mitochondrion-related organelles in anaerobic parasitic protozoa. Biochimie, 100, 3-17. Mller, M., Mentel, M., Hellemond, J. J., Henze, K., Woehle, C., Gould, S. B., et al. (2012). Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes. Microbiology and Molecular Biology Reviews, 76(2): 444-495. Stairs, C. W., Leger, M. M., Roger, A. J. (2015). Diversity and origins of anaerobic metabolism in mitochondria and related organelles. Philosophical Transactions of the Royal Society of Biology, DOI: 10.1098/rstb.2014.0326. Thiergart, T., Landan, G., Marc Schenk, T. D. (2012). An Evolutionary Network of Genes Present in the Eukaryote Common Ancestor Polls Genomes on Eukaryotic and Mitochondrial Origin. Genome Biology and Evolution, 4(4), 466-485.