Medaka fish exhibits longevity gender gap,a natural drop in estrogen and telomere shortening during aging: a unique model for studying sex-dependent longevity

Introduction

Females having a longer telomere and lifespan than males have been documented in many animals. Such linkage however has never been reported in fish. Progressive shortening of telomere length is an important aging mechanism. Mounting in vitro evidence has shown that telomere shortening beyond a critical length triggered replicative senescence or cell death. Estrogen has been postulated as a key factor contributing to maintenance of telomere and sex-dependent longevity in animals. This postulation remains unproven due to the lack of a suitable animal system for testing. Here, we introduce a teleost model, the Japanese medaka Oryzias latipes, which shows promise for research into the molecular mechanism(s) controlling sex difference in aging.

Results

Using the medaka, we demonstrate for the first time in teleost that (i) sex differences (female?>?male) in telomere length and longevity also exist in fish, and (ii) a natural, ‘menopause’-like decline of plasma estrogen was evident in females during aging. Estrogen levels significantly correlated with telomerase activity as well as telomere length in female organs (not in males), suggesting estrogen could modulate telomere length via telomerase activation in a sex -specific manner. A hypothetical in vivo ‘critical’ terminal restriction fragment (TRF, representing telomere) length of approximately 4 kb was deduced in medaka liver for prediction of organismal mortality, which is highly comparable with that for human cells. An age conversion model was also established to enable age translation between medaka (in months) and human (in years). These novel tools are useful for future research on comparative biology of aging using medaka.

Conclusion

The striking similarity in estrogen profile between aging female O. latipes and women enables studying the influence of “postmenopausal” decline of estrogen on telomere and longevity without the need of invasive ovariectomy. Medaka fish is advantageous for studying the direct effect of increased estrogen on telomere length and longevity without the breast cancer complications reported in rodents. The findings strongly support the notion that O. latipes is a unique non-mammalian model for validation of estrogenic influence on telomere and longevity in vertebrates. This laboratory model fish is of potential significance for deciphering the ostensibly conserved mechanism(s) of sex-associated longevity in vertebrates.

     

Variation of soil respiration and its components in hemiboreal Norway spruce stands of different ages

Aims

Understanding the linkage of soil respiration (Rs) with forest development is essential for long-term C cycle models. We estimated the variation and temperature sensitivity (Q₁₀ value) of Rs and its hetero-, (Rh) and autotrophic (Ra) components in relation to abiotic and biotic factors in Norway spruce stands of different ages, and the effect of trenching on microbial and soil characteristics.

Methods

Trenching method was used to partition Rs into Rh and Ra. Ingrowth core method was used to estimate fine root production. Soil microbial biomass was measured using manometric respirometers.

Results

Rs varied in differently aged stands demonstrating non-linear response to development stage. The variation of Rs was explained by changes in biotic factors rather than by changes in soil microclimate. Rh was more sensitive to Ts than Rs or Ra. After 4 years of trenching soil pH, N, SOM and dehydrogenase activity were significantly changed in trenched plots compared to control plots.

Conclusions

Different Q₁₀ values of Rh and Ra in stands of different ages indicate the importance of Rs partitioning. Trenching should be used during a limited number of years because of the possible changes in chemical characteristics of soil and in the activity of soil microbial community.

     

Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.     

A critical review on brain and heart axis response in COVID-19 patients: Molecular mechanisms,mediators, biomarkers,and therapeutics

Since the outbreak of highly virulent coronaviruses, significant interest was assessed to the brain and heart axis (BHA) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-affected patients. The majority of clinical reports accounted for unusual symptoms associated with SARS-CoV-2 infections which are of the neurological type, such as headache, nausea, dysgeusia, anosmia, and cerebral infarction. The SARS-CoV-2 enters the cells through the angiotensin-converting enzyme (ACE-2) receptor. Patients with prior cardiovascular disease (CVD) have a higher risk of COVID-19 infection and it has related to various cardiovascular (CV) complications. Infected patients with pre-existing CVDs are also particularly exposed to critical health outcomes. Overall, COVID-19 affected patients admitted to intensive care units (ICU) and exposed to stressful environmental constraints, featured with a cluster of neurological and CV complications. In this review, we summarized the main contributions in the literature on how SARS-CoV-2 could interfere with the BHA and its role in affecting multiorgan disorders. Specifically, the central nervous system involvement, mainly in relation to CV alterations in COVID-19-affected patients, is considered. This review also emphasizes the biomarkers and therapy options for COVID-19 patients presenting with CV problems.