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High mitochondrial densities in the hearts of Antarctic icefishes are maintained by an increase in mitochondrial size rather than mitochondrial biogenesis.
J Exp Biol. 2008 Aug; 211(Pt 16):2638-46.JE

Abstract

We investigated the molecular mechanisms regulating differences in mitochondrial volume density between heart ventricles of Antarctic notothenioids that vary in the expression of hemoglobin (Hb) and myoglobin (Mb). In mammals, peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) and nuclear respiratory factor 1 (NRF-1) stimulate mitochondrial biogenesis and maintain mitochondrial density in muscle tissues. We hypothesized that these factors would also maintain mitochondrial density in the hearts of Antarctic notothenioids. The percent cell volume occupied by mitochondria is significantly lower in hearts of the red-blooded notothenioid Notothenia coriiceps (18.18+/-0.69%) in comparison with those of the icefish Chaenocephalus aceratus (36.53+/-2.07%), which lacks both Hb and cardiac Mb. Mitochondrial densities are not different between hearts of N. coriiceps and Chionodraco rastrospinosus, which lacks Hb, but whose heart expresses Mb. Despite differences in mitochondrial volume density between hearts of N. coriiceps and C. aceratus, the levels of transcripts of the genes encoding PGC-1alpha, NRF-1 and citrate synthase, and the copy number of mitochondrial DNA do not differ. Our results indicate that the high mitochondrial densities in hearts of C. aceratus may result from an increase in organelle size. The surface-to-volume ratio of mitochondria from N. coriiceps is 1.9-fold greater than that of mitochondria from C. aceratus. In addition, the levels of PGC-1alpha correlate with mitochondrial density in muscle tissues of notothenioids possessing mitochondria of similar size and morphology. Finally, the levels of PGC-1alpha are 4.6-fold higher in the aerobic pectoral adductor muscle in comparison with the glycolytic skeletal muscle of N. coriiceps. The potential physiological significance of an increase in mitochondrial size in hearts of Antarctic icefishes is discussed.

Authors+Show Affiliations

University of Alaska, Fairbanks, Institute of Arctic Biology, PO Box 757000, Fairbanks, AK 99775, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

18689417

Citation

Urschel, Matthew R., and Kristin M. O'Brien. "High Mitochondrial Densities in the Hearts of Antarctic Icefishes Are Maintained By an Increase in Mitochondrial Size Rather Than Mitochondrial Biogenesis." The Journal of Experimental Biology, vol. 211, no. Pt 16, 2008, pp. 2638-46.
Urschel MR, O'Brien KM. High mitochondrial densities in the hearts of Antarctic icefishes are maintained by an increase in mitochondrial size rather than mitochondrial biogenesis. J Exp Biol. 2008;211(Pt 16):2638-46.
Urschel, M. R., & O'Brien, K. M. (2008). High mitochondrial densities in the hearts of Antarctic icefishes are maintained by an increase in mitochondrial size rather than mitochondrial biogenesis. The Journal of Experimental Biology, 211(Pt 16), 2638-46. https://doi.org/10.1242/jeb.018598
Urschel MR, O'Brien KM. High Mitochondrial Densities in the Hearts of Antarctic Icefishes Are Maintained By an Increase in Mitochondrial Size Rather Than Mitochondrial Biogenesis. J Exp Biol. 2008;211(Pt 16):2638-46. PubMed PMID: 18689417.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - High mitochondrial densities in the hearts of Antarctic icefishes are maintained by an increase in mitochondrial size rather than mitochondrial biogenesis. AU - Urschel,Matthew R, AU - O'Brien,Kristin M, PY - 2008/8/12/pubmed PY - 2008/10/10/medline PY - 2008/8/12/entrez SP - 2638 EP - 46 JF - The Journal of experimental biology JO - J. Exp. Biol. VL - 211 IS - Pt 16 N2 - We investigated the molecular mechanisms regulating differences in mitochondrial volume density between heart ventricles of Antarctic notothenioids that vary in the expression of hemoglobin (Hb) and myoglobin (Mb). In mammals, peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) and nuclear respiratory factor 1 (NRF-1) stimulate mitochondrial biogenesis and maintain mitochondrial density in muscle tissues. We hypothesized that these factors would also maintain mitochondrial density in the hearts of Antarctic notothenioids. The percent cell volume occupied by mitochondria is significantly lower in hearts of the red-blooded notothenioid Notothenia coriiceps (18.18+/-0.69%) in comparison with those of the icefish Chaenocephalus aceratus (36.53+/-2.07%), which lacks both Hb and cardiac Mb. Mitochondrial densities are not different between hearts of N. coriiceps and Chionodraco rastrospinosus, which lacks Hb, but whose heart expresses Mb. Despite differences in mitochondrial volume density between hearts of N. coriiceps and C. aceratus, the levels of transcripts of the genes encoding PGC-1alpha, NRF-1 and citrate synthase, and the copy number of mitochondrial DNA do not differ. Our results indicate that the high mitochondrial densities in hearts of C. aceratus may result from an increase in organelle size. The surface-to-volume ratio of mitochondria from N. coriiceps is 1.9-fold greater than that of mitochondria from C. aceratus. In addition, the levels of PGC-1alpha correlate with mitochondrial density in muscle tissues of notothenioids possessing mitochondria of similar size and morphology. Finally, the levels of PGC-1alpha are 4.6-fold higher in the aerobic pectoral adductor muscle in comparison with the glycolytic skeletal muscle of N. coriiceps. The potential physiological significance of an increase in mitochondrial size in hearts of Antarctic icefishes is discussed. SN - 0022-0949 UR - https://www.unboundmedicine.com/medline/citation/18689417/High_mitochondrial_densities_in_the_hearts_of_Antarctic_icefishes_are_maintained_by_an_increase_in_mitochondrial_size_rather_than_mitochondrial_biogenesis_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=18689417 DB - PRIME DP - Unbound Medicine ER -