Does oxidative stress shorten telomeres?

Abstract

Oxidative stress shortens telomeres in cell culture, but whether oxidative stress explains variation in telomere shortening in vivo at physiological oxidative stress levels is not well known. We therefore tested for correlations between six oxidative stress markers and telomere attrition in nestling birds (jackdaws Corvus monedula) that show a high rate of telomere attrition in early life. Telomere attrition was measured between ages 5 and 30 days, and was highly variable (average telomere loss: 323 bp, CV = 45%). Oxidative stress markers were measured in blood at age 20 days and included markers of oxidative damage (TBARS, dROMs and GSSG) and markers of antioxidant protection (GSH, redox state, uric acid). Variation in telomere attrition was not significantly related to these oxidative stress markers (|r| ≤ 0.08, n = 87). This finding raises the question whether oxidative stress accelerates telomere attrition in vivo The accumulation of telomere attrition over time depends both on the number of cell divisions and on the number of base pairs lost per DNA replication and, based on our findings, we suggest that in a growing animal cell proliferation, dynamics may be more important for explaining variation in telomere attrition than oxidative stress.

Keywords: development; molecular ecology; nestlings; somatic damage; telomere attrition.

Figure 1.

Telomere length at age 30 days plotted against telomere length at age 5 days in jackdaw nestlings (r = 0.97, n = 87). The dashed line represents equal values of day 5 and 30 telomere lengths and hence the distance below this line reflects the telomere shortening.

Figure 2.

Association between oxidative stress variables and telomere shortening (n = 87). The oxidative stress variables were transformed to a standard normal distribution and units on the x-axis therefore represent standard deviations. d-ROMS and uric acid were corrected for plasma triglycerides and handling time, respectively (see the electronic supplementary material SI for details). The Pearson correlation coefficients (r) are based on the data as shown, but p-values are from the mixed models. (Online version in colour.)