DNA MMR systems, microsatellite instability and antioxidant activity variations in two species of wild bats: Myotis velifer and Desmodus rotundus, as possible factors associated with longevity

Abstract

The accumulation of oxidative damage to biomolecules, such as DNA, is known to induce alterations in the cell's mechanisms and structure that might lead to the aging process. DNA mismatch repair system (MMR) corrects base mismatches generated during DNA replication that have escaped the proofreading process. In addition, antioxidant enzymes can reduce reactive oxygen species effects in order to protect cells from oxidizing damage. In order to determine the importance of these associated factors during the aging process, in this study, levels of MMR proteins MSH2 and MLH1, as well as microsatellite markers, were compared in liver, lung, and brain of juvenile, adult, and old, both female and male, individuals from two species of wild bats: the short-lived Myotis velifer and the longer lived Desmodus rotundus. Catalase, glutathione peroxidase, and superoxide dismutase were also analyzed to determine if the antioxidant protection correlates negatively with DNA damage. Antioxidant activities were higher in the longer lived D. rotundus than in M. velifer. Furthermore, old M. velifer but not old D. rotundus bats had reduced MMR levels and increased microsatellite instability. Therefore, although our results correlate the reduced MMR efficiency, the deficient antioxidant activity, and the increase in DNA damage with the aging process, this is not always true for all living organisms.

Fig. 1

Levels of MMR proteins in Myotis velifer. The figure shows representative blot and densitometry performed for MSH2 levels in a liver, b lung, and c brain as well as MLH1 levels from d liver, e lung, and f brain. MMR protein levels were compared between age and gender groups. Relative optic density was normalized against juvenile animals as control. Each point represents the mean ± S.D. of five determinations performed in independent donor animals. Statistical significance with respect to control (juvenile group) (a) or adult (b) p < 0.05 was considered. Letter c stands for statistical significance between genders (p < 0.05). MSH2 protein weight= 100 kDa; MLH1 protein weight= 85 kDa; actin protein weight= 42 kDa

Fig. 2

Levels of MMR proteins in Desmodus rotundus. The figure shows representative blot and densitometry performed for MSH2 levels in a liver, b lung, and c brain as well as MLH1 levels from d liver, e lung, and f brain. MMR protein levels were compared between age and gender groups. Relative optic density was normalized against juvenile animals as control. Each point represents the mean ± S.D. of five determinations performed in independent donor animals. Statistical significance with respect to control (juvenile group) (a) or adult (b) p < 0.05 was considered. Letter c stands for statistical significance between genders (p < 0.05). MSH2 protein weight= 100 kDa; MLH1 protein weight= 85 kDa; actin protein weight= 42 kDa

Fig. 3

Microsatellite markers in Myotis velifer. The figure shows representative images and densitometry performed for microsatellite MS3DO2 levels in a liver, b lung, and c brain as well as MS3EO2 levels from d liver, e lung, and f brain. Microsatellite levels were compared between age and gender groups. Relative optic density was normalized against juvenile animals as control. Each point represents the mean ± S.D. of five determinations performed in independent donor animals. Statistical significance with respect to control (juvenile group) (a) or adult (b) p < 0.05 was considered. Letter c) stands for statistical significance between genders (p < 0.05). MS3DO2 weight= 229 pb; MS3EO2 weight= 409 pb; actin weight= 150 pb

Fig. 4

Microsatellite markers in Desmodus rotundus. The figure shows representative images and densitometry performed for microsatellite DESMOO levels in a liver, b lung, and c brain as well as DESMO1 levels from d liver, e lung, and f brain. Microsatellite levels were compared between age and gender groups. Relative optic density was normalized against juvenile animals as control. Each point represents the mean ± S.D. of five determinations performed in independent donor animals. Statistical significance with respect to control (juvenile group) (a) or adult (b) p < 0.05 was considered. Letter c stands for statistical significance between genders (p < 0.05). DESMOO weight= 200 pb; DESMO1 weight= 300 pb; actin weight= 150 pb

Fig. 5

Myotis velifer comparison between MMR levels and MSI. The figures shows comparisons between MSI levels against MMR proteins levels found in a liver, b lung, and c brain as well as comparing MSI levels against CAT activity levels from d liver, e lung, and f brain in female (F) and male (M) bats of Myotis velifer

Fig. 6

Desmodus rotundus comparison between MMR levels and microsatellite instability. The figures shows comparisons between MSI levels against MMR proteins levels found in a liver, b lung, and c brain as well as comparing MSI levels against CAT activity levels from d liver, e lung, and f brain in female (F) and male (M) bats of Desmodus rotundus