Redox-regulation and life-history trade-offs: scavenging mitochondrial ROS improves growth in a wild bird

Velando, A., Noguera, J.C., da Silva, A. e Kim, S.Y., 2019. Redox-regulation and life-history trade-offs: scavenging mitochondrial ROS improves growth in a wild bird. Scientific reports, 9(1), p.2203.

It has been proposed that animals usually restrain their growth because fast growth leads to an increased production of mitochondrial reactive oxygen species (mtROS), which can damage mitochondrial DNA and promote mitochondrial dysfunction. Here, we explicitly test whether this occurs in a wild bird by supplementing chicks with a mitochondria-targeted ROS scavenger, mitoubiquinone (mitoQ), and examining growth rates and mtDNA damage. In the yellow-legged gull Larus michahellis, mitoQ supplementation increased the early growth rate of chicks but did not reduce mtDNA damage. The level of mtDNA damage was negatively correlated with chick mass, but this relationship was not affected by the mitoQ treatment. We also found that chick growth was positively correlated with both mtDNA copy number and the mitochondrial enzymatic activity of citrate synthase, suggesting a link between mitochondrial content and growth. Additionally, we found that mitoQ supplementation increased mitochondrial content (in males), altered the relationship between mtDNA copy number and damage, and downregulated some transcriptional pathways related to cell rejuvenation, suggesting that scavenging mtROS during development enhanced growth rates but at the expense of cellular turnover. Our study confirms the central role of mitochondria modulating life-history trade-offs during development by other mechanisms than mtROS-inflicted damage.

 

Multilocus population analysis of Gavia immer (Aves: Gaviidae) mtDNA reveals low genetic diversity and lack of differentiation across the species breeding range

Bartolomé, C., Maside, X., Camphuysen, K.C., Heubeck, M. & Bao, R., 2011. Multilocus population analysis of Gavia immer (Aves: Gaviidae) mtDNA reveals low genetic diversity and lack of differentiation across the species breeding range. Organisms Diversity & Evolution, 11(4), pp.307-316.


We analyzed the patterns of nucleotide sequence variation at three mitochondrial DNA loci, the noncoding mitochondrial control region and two genes (cytochrome b and cytochrome oxidase I) of Gavia immer in the largest collection of wintering individuals from Southern Europe to date. The sample consisted of 33 birds, oiled during the 2002/2003 Prestige tanker spill and washed ashore on the Galician coast (NW Iberian Peninsula). The aims of the study were to investigate the levels of standing genetic variation in the species, and to identify the geographic origin of these wintering birds. To do this, all available sequences of these loci, mostly from North American specimens collected from both the Atlantic and Pacific coasts, were retrieved from GenBank and included in the analysis. Overall, only 14 genetic variants were detected in the nearly 2 Kb surveyed, which reflects very low levels of nucleotide site diversity in this species. Interestingly, all variants were found at very low frequencies, and there was no indication of any clear subdivision in the G. immer population. This genetic profile is consistent with G. immer being a single panmictic population of small effective population size as compared with other seabirds. These circumstances preclude identification of the breeding regions of these wintering birds relying solely on genetic data. In the light of these results, possible causes, and the genetic and ecological consequences, of this demographic scenario are discussed.