No Evidence for Trade-Offs Between Lifespan, Fecundity, and Basal Metabolic Rate Mediated by Liver Fatty Acid Composition in Birds

The fatty acid composition of biological membranes has been hypothesised to be a key molecular adaptation associated with the evolution of metabolic rates, ageing, and life span – the basis of the membrane pacemaker hypothesis (MPH). MPH proposes that highly unsaturated membranes enhance cellular metabolic processes while being more prone to oxidative damage, thereby increasing the rates of metabolism and ageing. MPH could, therefore, provide a mechanistic explanation for trade-offs between longevity, fecundity, and metabolic rates, predicting that short-lived species with fast metabolic rates and higher fecundity would have greater levels of membrane unsaturation. However, previous comparative studies testing MPH provide mixed evidence regarding the direction of covariation between fatty acid unsaturation and life span or metabolic rate. Moreover, some empirical studies suggest that an n-3/n-6 PUFA ratio or the fatty acid chain length, rather than the overall unsaturation, could be the key traits coevolving with life span. In this study, we tested the coevolution of liver fatty acid composition with maximum life span, annual fecundity, and basal metabolic rate (BMR), using a recently published data set comprising liver fatty acid composition of 106 avian species. While statistically controlling for the confounding effects of body mass and phylogeny, we found no support for long life span evolving with low fatty acid unsaturation and only very weak support for fatty acid unsaturation acting as a pacemaker of BMR. Moreover, our analysis provided no evidence for the previously reported links between life span and n-3 PUFA/total PUFA or MUFA proportion. Our results rather suggest that long life span evolves with long-chain fatty acids irrespective of their degree of unsaturation as life span was positively associated with at least one long-chain fatty acid of each type (i.e., SFA, MUFA, n-6 PUFA, and n-3 PUFA). Importantly, maximum life span, annual fecundity, and BMR were associated with different fatty acids or fatty acid indices, indicating that longevity, fecundity, and BMR coevolve with different aspects of fatty acid composition. Therefore, in addition to posing significant challenges to MPH, our results imply that fatty acid composition does not pose an evolutionary constraint underpinning life-history trade-offs at the molecular level.

Novel Method for Early Detection and Classification of Neuro Degenerative Disorder Amyotrophic Lateral Sclerosis

The most common progressive neurodegenerative disorder in the fetal nature is amyotrophic lateral sclerosis (ALS). The ALS incidence is approximately 2 per 100 000, with the maximum life span being two to three years after the start of symptomatic growth. However, premature identification may increase the lives of the impacted people. EEG is the most convenient and cheapest technique for measuring brain electrical activity. Automated EEG can be used as the coherent identification biomarker technique which is always connected with fronto-temporal dementia (FTD) in seconds to detect ALS in previous phases of growth. The EEG spatial assessment will show spatial and behavioral structure changes in the fundamental cellular network resulting from FTD and may produce prospective biomarkers for premature identification of ALS. The use of the Dual Tree Complex Wavelet Transformation (DTCWT) technique has developed a novel algorithm. DTCWT can solve the abbreviation of current EEG removal functionality techniques. The spectral leakage is reduced by a ideal rebuilding of the DTCWT measurements, so the suggested algorithm has led to an effective and coherent ALS ranking with a Neural Network (NN). For analyzes, eight EEG datasets, each of the Normal Group and Subject were used, and spectral EEG analysis provided a source of definite biomarkers. The proposed algorithm produced 100 percentage accuracy with respect to the dataset considered in this analysis.

Life span bias explains live–dead discordance in abundance of two common bivalves

Life span bias potentially alters species abundance in death assemblages through the overrepresentation of short-lived organisms compared with their long-lived counterparts. Although previous work found that life span bias did not contribute significantly to live–dead discordance in bivalve assemblages, life span bias better explained discordance in two groups: longer-lived bivalve species and species with known life spans. More studies using local, rather than global, species-wide life spans and mortality rates would help to determine the prevalence of life span bias, especially for long-lived species with known life spans. Here, we conducted a field study at two sites in North Carolina to assess potential life span bias between Mercenaria mercenaria and Chione elevata, two long-lived bivalve species that can be aged directly. We compared the ability of directly measured local life spans with that of regional and global life spans to predict live–dead discordance between these two species. The shorter-lived species (C. elevata) was overrepresented in the death assemblage compared with its live abundance, and local life span data largely predicted the amount of live–dead discordance; local life spans predicted 43% to 88% of discordance. Furthermore, the global maximum life span for M. mercenaria resulted in substantial overpredictions of discordance (1.4 to 1.6 times the observed live–dead discordance). The results of this study suggest that life span bias should be considered as a factor affecting proportional abundances of species in death assemblages and that using life span estimates appropriate to the study locality improves predictions of discordance based on life span compared with using global life span estimates.

Record longevity of a Spotted Turtle (Clemmys guttata)

Turtles are known for their longevity, but the maximum life span for many species remains unknown. Spotted Turtle (Clemmys guttata) can live for more than 30 years in the wild, but typical or maximum longevity has not been confirmed. As part of a long-term mark–recapture project in Ottawa, Ontario, near the species’ northern limit, an adult female was captured on 27 April 2017. It had first been marked on 11 June 1983, when it was an adult with 17 growth rings on its plastron. Based on the number of growth rings at first capture, and the intervening time, this turtle is a minimum of 51 years old, setting a longevity record for the species. Ten individuals in this population were at least 30 years old when last captured, including a male at least 41 years old. Few of these turtles have grown measurably since being marked in 1983, and it is likely that these minimum ages are underestimates of actual ages.

Life extension in Drosophila melanogasteras a result of development in conditions of high larval density

Aim. To investigate the life expectancy and reproductive activity of Drosophila melanogaster that developed in conditions of increased larval density. Methods. Mean and maximum life span were determined in males and females in the different experimental groups. The reproductive activity was evaluated by counting the total number of eggs laid by one female per day. Results. A significant increase of the mean life span compared to control was observed in adults that hatched from pupae during the first and second days after the beginning of the emergence: males — 24 % and 23.5 %, females — 23.8 % and 29.3 % respectively. The level of reproductive activity (fecundity) is statistically lower in two groups which hatched last. Conclusions. Based on the results obtained, we suggest that development in conditions of increased larval density can lead to increase in the life span of D. melanogaster.Keywords: life span, Drosophila melanogaster, reproductive activity, development.

Development and lifespan duration of Drosophila melanogaster at the larval development under hypoxia and hyperoxia

Various environmental factors can affect metabolic processes, physiological parameters and the lifespan of the whole organism. Since aging can be considered as part of development in accordance with the "developmental theory of aging", we can assume that development duration correlates with adult lifespan. Understanding how organisms react to different concentrations of O2 is an area of intense scientific study. It is known that ambient oxygen level affects body size, growth and development rates, cell cycle duration in Drosophila melanogaster, but data on the impact on lifespan remain controversial. In this study, we studied the influence of hypoxia (10% O2) and hyperoxia (40% O2) at the larval stage of development on the duration of Drosophila development and lifespan. Drosophila kept in atmospheric air (21% O2) was used as control. At the imago stage all the flies were kept in atmospheric air conditions. The results were presented as survival curves and average and maximum lifespan were calculated. The development duration of Drosophila melanogaster, which were kept under hypoxia, increased by one day compared to control and did not change at hyperoxia. Average and maximum life span significantly decreased at hyperoxia (average – by 17% in males and 10% in females, maximum – by 17% in males, p<0,001). Hypoxia in different ways influenced males and females. The average lifespan of males did not significantly change and the maximum – increased by 11% (p<0.001). In females, hypoxia during development led to a decrease in average lifespan by 18% and in maximum life span by 8%. The data obtained during our investigation allow us to conclude that the concentration of oxygen in the environment at the stage of development of Drosophila affects their life expectancy at the stage of imago, which can be explained by epigenetic mechanisms. Hyperoxia at the developmental stage adversely affected the life expectancy of fruit flies, probably due to the adverse effects of free-radical processes. Sex differences in the effects of hypoxia at the developmental stage were revealed. In female flies, it led to negative effects, while in males development under hypoxic conditions extended life span, probably due to the phenomenon of hormesis.

Body size and age structure of the endangered Clark’s lizard (Darevskia clarkorum) populations from two different altitudes in Turkey

We investigated age structure, body size and longevity in two breeding populations ofDarevskia clarkoruminhabiting altitudes ranging from 450 m a.s.l. (Kamilet) to 2250 m a.s.l. (Başyayla) in Turkey by skeletochronology performed on the phalanges. The mean age was found to be 6 years in the Kamilet population and 7 years in the Başyayla population. The maximum life span was 10 years in the lowland population while it was 12 years in the highland population. Age at sexual maturity of both males and females was 1-2 years in the lowland population while it was 2-3 for both sexes in the highland population. Both age and SVL of specimens from the Kamilet population were significantly different between the sexes while age and SVL did not differ significantly between the sexes in Başyayla population. As a conclusion, we observed that the mean age, longevity and age at maturity were increased by altitude while there was a decrease based on the mean SVL in the highland population ofD. clarkorum. Our data on body size, longevity and age at sexual maturity may contribute to conservation efforts for this endangered species.