Aging in Birds

DNA damage (8-OHdG) and telomere length in captive Psittacidae birds with different longevity

Aging is a complex process influenced by internal and external factors. Oxidative stress damages DNA, leading to 8-hydroxy-2' deoxyguanosine formation (8-OHdG). Telomere shortening is considered a biomarker of aging and oxidative stress may enhance its attrition. The ability to manage and repair oxidative stress varies among species and life histories. Avian species, such as Psittacidae birds, exhibit exceptional lifespans despite their physiological characteristics that might suggest otherwise. This study investigates 8-OHdG levels in serum samples from long- and short-lived birds of the order Psittaciformes, examining their relationship with telomere length and antioxidant capacity based on lifespan strategies. Among 43 individuals analyzed 26 belonged to the "long-lived species" group and 17 belonged to the "short-lived species" one. Relative telomere length (rTL) was measured in DNA isolated from whole blood by qPCR, and oxidative stress markers, such as Total Antioxidant Capacity (TAC) and 8-OHdG, were determined by spectrophotometry in serum samples. Long-lived birds had longer rTL than short-lived ones [1.308 ± 0.11 vs. 0.565 ± 0.13, (p < 0.001)]. On the contrary, short-lived birds showed more DNA damage than their counterparts [3.847 ± 0.351 vs. 2.012 ± 0.308, respectively, (p < 0.001)]. Old birds had shorter rTL than young ones, for both longevity groups (p < 0.001). Although no correlation was found between 8-OHdG levels and age, nor 8-OHdG and telomere length, long-lived birds exhibited 75.42-unit increased TAC levels when increased 8-OHdG concentrations (p = 0.046). These findings highlight distinct patterns of telomere length and oxidative stress influenced by lifespan strategies among avian longevity groups.

An approach to the effects of longevity, sexual maturity, and reproduction on telomere length and oxidative stress in different Psittacidae species

Introduction: Aging is a multifactorial process that includes molecular changes such as telomere shortening. Telomeres shorten progressively with age in vertebrates, and their shortening rate has a significant role in determining the lifespan of a species. However, DNA loss can be enhanced by oxidative stress. The need for novel animal models has recently emerged as a tool to gather more information about the human aging process. Birds live longer than other mammals of the same size, and Psittacidae species are the most persevering of them, due to special key traits. Methods: We aimed to determine telomere length by qPCR, and oxidative stress status using colorimetric and fluorescence methods in different species of the order Psittaciformes with different lifespans. Results: We found that telomeres shorten with age for both long- and short-lived birds (p < 0.001 and p = 0.004, respectively), with long-lived birds presenting longer telomeres than short-lived ones (p = 0.001). In addition, short-lived birds accumulated more oxidative stress products than long-lived birds (p = 0.013), who showed a better antioxidant capacity (p < 0.001). Breeding was found related to telomere shortening in all species (p < 0.001 and p = 0.003 for long- and short-lived birds). Short-lived birds, especially breeding females, increased their oxidative stress products when breeding (p = 0.021), whereas long-lived birds showed greater resistance and even increased their antioxidant capacity (p = 0.002). Conclusion: In conclusion, the relationship between age and telomere length in Psittacidae was verified. The influence of breeding increased cumulative oxidative damage in short-lived species, while long-lived species may counteract this damage.

Do the diverse environments of Baltic coastal zone affect hematological and biochemical alterations in the blood of mute swans (Cygnus olor)?

Based on studies of the wintering population of mute swans in large urban agglomerations, it is possible to identify and infer the impact of environmental pollution in coastal regions near Baltic Sea on the physiological and biochemical changes in the blood of waterfowls. Hematological and biochemical changes in the blood in relation to chemical elements in their feathers are a useful tool for general ecophysiological conclusions. Hematological changes and blood chemistry in Mute Swan Cygnus olor is particularly environmentally dependent, therefore we examined hematological picture (red blood cells RBC, white blood cells WBC, heterophiles, eosinophils, basophils, monocytes, lymphocytes, hemoglobin, heterophile to lymphocyte ratio H/L, biochemical indicators (glucose, uric acid, total cholesterol, triglycerides, calcium, inorganic phosphorus, magnesium, total protein), stability of erythrocyte membranes, concentration of Ca, P, Mg in the blood, concentration of Al, Zn, Rh, Cu, Ru, Fe, Pb in feathers, in wintering population of 172 mute swans of different age (juvenile, adult) and gender, in three coastal types of areas of Southern Polish zone of Baltic Sea (Słupsk, Gdynia, Sopot). Percentage of changes in the morphological indices in the blood of mute swans with three independent characteristics (environment, sex, age) revealed that hemoglobin content exhibited the highest value (R² = 53.8%) in the analysis of morphological indices; the effect of RBC, WBC, and basophils was much lower (WBC > RBC > basophils). Male and female erythrocytes from the coastal of Gdynia were more fragile than those of birds from coasts of Sopot and Słupsk. We found that osmotic fragility is altered in juvenile swans from Słupsk area and males from Gdynia area. The consequence was a higher level of hemolyzed erythrocytes in their blood. The effect of type of environment, age-, and sex-related impact on hematological indices and biomarkers of biochemical alterations in the blood of swans and comparison of these data with bioaccumulation of chemical elements in feathers of swans inhabiting 3 types of environment of Baltic coastal zone show significant differences in the hematological and biochemical indices. Albumins and globulins maintain the blood cations balance, however, changes in their concentrations in the blood suggest an impact on physiological mechanisms and body condition of swans.

Bird evolution by insulin resistance

Drift of oxygen concentrations in the atmosphere was one of the main drivers of the evolution of vertebrates. The drop in oxygen concentrations at the Permian-Triassic (PT) boundary may have been the biggest challenge to vertebrates. This hypoxic condition forced theropods to lose certain genes to maximize their efficiency of oxygen usage. Recent studies show that omentin and insulin-sensitive glucose transporter 4 (GLUT4) are missing in the bird genome. Since these gene products play essential roles in maintaining insulin sensitivity, this loss forced theropods to become insulin resistant. Insulin resistance may have been the key to allowing theropods to become hyperathletic under hypoxic conditions and to outcompete mammals during the Triassic period. A second challenge was the gradual increase in oxygen concentrations during the late Jurassic, Cretaceous, and Tertiary periods when reactive oxygen species (ROS) leakage from mitochondria became a problem. Since the simplest solution was the expansion of body size, some theropods became bigger to reduce ROS leakage per volume. Another solution was the development of a constitutively active countermeasure against ROS. A recent study shows that Neoaves have constitutively active nuclear factor erythroid 2-related factor 2 (NRF2) due to deletion of the C-terminal part of the KEAP1 protein, thus allowing Neoaves to express antioxidant enzymes to overcome ROS leakage.

Fewer Exposed Lysine Residues May Explain Relative Resistance of Chicken Serum Albumin to In Vitro Protein Glycation in Comparison to Bovine Serum Albumin

Protein glycation and formation of advanced glycation end products is associated with several diseases resulting from high blood glucose concentrations. Plasma albumin is directly exposed to circulating glucose concentrations and is therefore at greater risk of glycation than hemoglobin. As plasma glucose concentrations in birds are 1.5-2 times higher than mammals of similar mass, avian albumin may be particularly at risk of glycation. Thus, the goal of the present study was to compare the in vitro formation of glycated albumin in chicken serum albumin (CSA) and bovine serum albumin (BSA) exposed to a range of glucose concentrations over a 16-week period. The level of glycation for CSA and BSA was quantified using boronate affinity columns to separate glycated albumin from non-glycated albumin and calculating the difference in protein concentration of each sample. The results indicate that CSA is glycated to a lesser degree than BSA when the albumins are exposed to increasing concentrations of glucose (38.8-500 mM). This was most apparent at week sixteen (500 mM glucose) where BSA expressed a higher degree of glycation (37.8 ± 0.76%) compared to CSA (19.7 ± 1.06%, P < 0.05). Additionally, percent glycation at week sixteen was significantly higher than the glucose-free solutions for both BSA and CSA, indicating that glycation is glucose-dependent. Analyses of the protein structures suggest that the relative resistance of CSA to glycation may be due to fewer lysine residues and variations in protein folding that shield more lysine residues from the plasma. Moreover, comparisons of reconstructed ancestral albumin sequences show that the ancestor of birds had 6-8 fewer lysine residues compared to that of mammals.

Bacteria in the ageing gut: did the taming of fire promote a long human lifespan?

Unique among animals as they evolved towards Homo sapiens, hominins progressively cooked their food on a routine basis. Cooked products are characterized by singular chemical compounds, derived from the pervasive Maillard reaction. This same reaction is omnipresent in normal metabolism involving carbonyls and amines, and its products accumulate with age. The gut microbiota acts as a first line of defence against the toxicity of cooked Maillard compounds, that also selectively shape the microbial flora, letting specific metabolites to reach the blood stream. Positive selection of metabolic functions allowed the body of hominins who tamed fire to use and dispose of these age-related compounds. I propose here that, as a hopeful accidental consequence, this resulted in extending human lifespan far beyond that of our great ape cousins. The limited data exploring the role of taming fire on the human genetic setup and on its microbiota is discussed in relation with ageing.