Mitochondria: aerobic and anaerobic design—lessons from molluscs and fishes

Biochemistry and Evolution of Anaerobic Energy Metabolism in Eukaryotes

“…ATP generation by these pathways is equivalent to that of lactate formation, with 2 mol ATP per mol glucose degraded. The suggested advantage of the opine pathways is that the anaerobic opine end products are less acidic than lactate, and, because 1 amino acid is consumed for each opine synthesized, these end products are produced in an osmotically neutral process that reduces the os-motic stress associated with the accumulation of lactate (24). The enormous amino acid pools maintained by mollusks for osmotic balance are the source of amino acids for this process.…”

“…With regard to the problematic circumstance that H 2 production from NAD(P)H is sketched, see the text. Abbreviations: Fd, ferredoxin; [2], acetate:succinate CoA-transferase; [3], succinyl-CoA synthetase; [4], hydrogenase; [5], malic enzyme; [8], fumarase; [9], pyruvate kinase; [10], phosphoenolpyruvate carboxykinase (ATP dependent); [11], malate dehydrogenase; [12], lactate dehydrogenase; [22], pyruvate:formate lyase; [23], NAD(P)H:ferredoxin oxidoreductase; [24], fumarate reductase (soluble); [25], alcohol dehydrogenase E. The photograph shows Piromyces sp. E2; the fluorescing region (sporangia and hyphae) is ca.…”

“…The 51-and 24-kDa subunits of complex I (209) have so far not been identified in T. foetus. Cytosolic succinate production through soluble fumarate reductase is lacking in metronidazole-resistant Tritrichomonas foetus strains (256 [5], malic enzyme; [8], fumarase; [9], pyruvate kinase; [11], malate dehydrogenase; [17], phosphoenolpyruvate carboxykinase (GTP dependent); [18], alanine aminotransferase; [24], fumarate reductase (soluble); [32], pyruvate decarboxylase; [34], alcohol dehydrogenase (NADPH dependent); [49], glycerol-3-phosphate dehydrogenase; [50], glycerol-3-phosphatase. The photograph shows Tritrichomonas foetus at the trophozoite stage, with a length of ca.…”

“…The respiratory chain contains not only an alternative oxidase and glycerol-3-phosphate dehydrogenase but also an alternative rotenone-insensitive NADH dehydrogenase (90). Abbreviations: CI to CIV, respiratory complexes I to IV; UQ, ubiquinone; C, cytochrome c; A, ATPase; AOX, alternative oxidase; AN, alternative, rotenone-insensitive NADH dehydrogenase; GPDH, glycerol-3-phosphate dehydrogenase; G3P, glycerol-3-phosphate; DHAP, dihydroxyacetone phosphate; GAP, glyceraldehyde-3-phosphate; PGA, 3-phosphoglycerate; [2A], acetate:succinate CoA-transferase (subfamily 1A); [3], succinyl-CoA synthetase; [5], malic enzyme; [6], pyruvate dehydrogenase complex; [8], fumarase; [9], pyruvate kinase; [10], phosphoenolpyruvate carboxykinase (ATP dependent); [11], malate dehydrogenase; [18], alanine aminotransferase; [24], fumarate reductase (soluble, NADH dependent); [42], ␣-ketoglutarate dehydrogenase; [43], citrate synthase.…”

Glutamine accumulation and up-regulation of glutamine synthetase activity in the swamp eel,Monopterus albus(Zuiew), exposed to brackish water

“…The first advantage is that accumulated glutamine could act as a precursor for the synthesis of physiologically important molecules such as purines, pyrimidines and mucopolysaccharides upon returning to freshwater. Studies have found that glutamine may be utilized by some teleosts as an oxidative substrate for red muscle mitochondria (Chamberlin et al, 1991;Chamberlin and Ballantyne, 1992;Mommsen et al, 2003;Ballantyne, 2004). Therefore, another possible advantage is that the accumulated glutamine may also serve as an alternative energy source for M. albus upon returning to favourable ambient conditions.…”