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. 2011 Apr;34(2):315-22.
doi: 10.1590/s1415-47572011000200025. Epub 2011 Apr 1.

Anoxia- and hypoxia-induced expression of LDH-A* in the Amazon Oscar, Astronotus crassipinis

Vera Maria Fonseca Almeida-Val  1 , Alice Reis Oliveira, Maria de Nazaré Paula da Silva, Monica Stropa Ferreira-Nozawa, Roziete Mendes Araújo, Adalberto Luis Val, Sérgio Ricardo Nozawa
Affiliations

Anoxia- and hypoxia-induced expression of LDH-A* in the Amazon Oscar, Astronotus crassipinis

Vera Maria Fonseca Almeida-Val et al. Genet Mol Biol. 2011 Apr.

Abstract

Adaptation or acclimation to hypoxia occurs via the modulation of physiologically relevant genes, such as erythropoietin, transferrin, vascular endothelial growth factor, phosphofructokinase and lactate dehydrogenase A. In the present study, we have cloned, sequenced and examined the modulation of the LDH-A gene after an Amazonian fish species, Astronotus crassipinis (the Oscar), was exposed to hypoxia and anoxia. In earlier studies, we have discovered that adults of this species are extremely tolerant to hypoxia and anoxia, while the juveniles are less tolerant. Exposure of juveniles to acute hypoxia and anoxia resulted in increased LDH-A gene expression in skeletal and cardiac muscles. When exposed to graded hypoxia juveniles show decreased LDH-A expression. In adults, the levels of LDH-A mRNA did not increase in hypoxic or anoxic conditions. Our results demonstrate that, when given time for acclimation, fish at different life-stages are able to respond differently to survive hypoxic episodes.

Keywords: Amazon; LDH-A; RT-PCR; anoxia; fishes; gene expression; hypoxia.

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Figures

Figure 1
Figure 1
Autoradiography and estimated relative expression of RNA in white muscle (top) and in heart (bottom) of juvenile Astronotus crassipinis under different oxygen levels and hybridized with LDH-A and rRNA probes. Fish were exposed to normoxia, hypoxia (8.5 kPa and 4.2 kPa) and anoxia (0.0 kPa).
Figure 2
Figure 2
LDH-A expression in white muscle and heart of juvenile and adult Astronotus crassipinis under normoxia and after 30 min of anoxia exposure.
Figure 3
Figure 3
Expression of LDH-A in the muscle of juvenile Astronotus crassipinis exposed to normoxia, hypoxia (17 kPa and 0.9 kPa) and anoxia for 8 h.
See this image and copyright information in PMC

References

    1. Almeida-Val VMF, Val AL. Evolutionary trends of LDH isozymes in fishes. Comp Biochem Physiol. 1993;105:21–28.
    1. Almeida-Val VMF, Val AL, Hochachka PW. Hypoxia tolerance in Amazon fishes: Status of an under-explored biological “goldmine”. In: Hochachka PW, Lutz PL, Sick T, Rosenthal M, Van den Thillart G, editors. Surviving Hypoxia: Mechanisms of Control and Adaptation. CRC Press; Boca Raton: 1993. pp. 435–445.
    1. Almeida-Val VMF, Farias IP, Silva MNP, Duncan WP. Biochemical adjustments to hypoxia in Amazon Cichlids. Braz J Med Biol Res. 1995;28:1257–1263. - PubMed
    1. Almeida-Val VMF, Val AL, Walker I. Long- and short-term adaptation of amazon fishes to varying O2 levels: Intra-specific phenotypic plasticity and interspecific variation. In: Val AL, Almeida-Val VMF, editors. Biology of Tropical Fishes. Editora do INPA; Manaus: 1999a. pp. 185–206.
    1. Almeida-Val VMF, Paula-Silva MN, Duncan WP, Lopes NP, Val AL. Increase of anaerobic potential during growth of an Amazonian cichlid, Astronotus ocellatus. Survivorship and LDH regulation after hypoxia exposure. In: Val AL, Almeida-Val VMF, editors. Biology of Tropical Fishes. Editora do INPA; Manaus: 1999b. pp. 437–448.

Internet Resources

    1. Chippari-Gomes AR, Val AL, Almeida-Val VMF. Comparative responses of closely related cichlids to graded hypoxia. International Congress on the Biology of Fish, Vancouver. Responses of Fish to Aquatic Hypoxia. 2002. pp. 9–13. ( http://www-heb.pac.dfo-mpo.gc.ca/congress/2002/Hypoxia/Chippari-Gomes.pdf).

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