title: Scaling effects on hypoxia tolerance in the Amazon fish Astronotus ocellatus (Perciformes: Cichlidae): contribution of tissue enzyme levels.
abstract: Astronotus ocellatus is one of the most hypoxia tolerant fish of the Amazon; adult animals can tolerate up to 6 h of anoxia at 28 degrees C. Changes in energy metabolism during growth have been reported in many fish species and may reflect the way organisms deal with environmental constraints. We have analyzed enzyme levels (lactate dehydrogenase, LDH: EC 1.1.1.27; and malate dehydrogenase, MDH: EC 1.1.1.37) in four different tissues (white muscle, heart, liver, and brain) from different-sized animals. Both enzymes correlate with body size, increasing the anaerobic potential positively with growth. To our knowledge, this is the first description of scaling effects on hypoxia tolerance and it is interesting to explore the fact that hypoxia survivorship increases due to combining effects of suppressing metabolic rates and increasing anaerobic power as fish grow.
authors.affiliation: National Institute for Amazon Research (INPA), Manaus AM, Brazil. veraval@inpa.gov.br
authors.forename: V M
authors.initials: VM
authors.lastname: Almeida-Val
authors.forename: A L
authors.initials: AL
authors.lastname: Val
authors.forename: W P
authors.initials: WP
authors.lastname: Duncan
authors.forename: F C
authors.initials: FC
authors.lastname: Souza
authors.forename: M N
authors.initials: MN
authors.lastname: Paula-Silva
authors.forename: S
authors.initials: S
authors.lastname: Land
mesh_terms: D000818:Animals; D001835:Body Weight; D001921:Brain / Q000201:enzymology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000378:metabolism*; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D010100:Oxygen / Q000502:physiology*; D010471:Perches / Q000502:physiology*; D012621:Seasons; D013223:Statistics as Topic; D014020:Tissue Extracts
chemical_list: D014020:Tissue Extracts; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D010100:Oxygen