Tag Archives: #biologicalage

New, Highly Precise ‘Clock’ Can Measure Biological Age (Biology)

Using the model organism Caenorhabditis elegans, researchers at the University of Cologne have developed an ‘aging clock’ that reads the biological age of an organism directly from its gene expression, the transcriptome. Bioinformatician David Meyer and geneticist Professor Dr Björn Schumacher, director of the Institute for Genome Stability in Aging and Disease at the CECAD Cluster of Excellence in Aging Research and the Center for Molecular Medicine Cologne (CMMC), describe their so-called BiT age (binarized transcriptomic aging clock) in the article ‘BiT age: A transcriptome based aging clock near the theoretical limit of accuracy’ in Aging Cell.

We are all familiar with chronological age – our age since birth. But biological age can differ from it, at times significantly. Everyone ages differently. Scientists can use aging clocks to determine an organism’s biological age. Until now, aging clocks such as Horvath’s epigenetic clock have been based on the pattern of methylations, small chemical groups that attach to DNA and change with age. Using the transcriptome, the new clock takes into consideration the set of genes that are read from DNA (messenger RNA) to make proteins for the cell.

Until now, the transcriptome was considered too complex to indicate age. Sometimes genes transcribe a particularly large amount of mRNA, sometimes less. Hence, so far it has not been possible to develop precise aging clocks based on gene activity. Meyer and Schumacher’s new approach uses a mathematical trick to eliminate the differences in gene activity. The binarized transcriptome aging clock divides genes into two groups – ‘on’ or ‘off’ – thus minimizing high variation. This makes aging predictable from the transcriptome. ‘Surprisingly, this simple procedure allows very accurate prediction of biological age, close to the theoretical limit of accuracy. Most importantly, this aging clock also works at high ages, which were previously difficult to measure because the variation in gene activity is particularly high then,’ said Meyer.

BiT age is based exclusively on approximately 1,000 different transcriptomes of C. elegans, for which the lifespan is precisely known. Model organisms such as the nematode provide a controllable view of the aging process, allowing biomarkers to be discovered and the effects of external influences such as UV radiation or nutrition on longevity to be studied.

The new aging clock allows researchers to accurately predict the pro- and anti-aging effects of gene variants and various external factors in the nematode at a young age. The aging clock also showed that genes of the immune response as well as signalling in neurons are significant for the aging process. ‘BiT age can also be applied to predict human age quickly and with very high accuracy. Measuring biological age is important to determine the influence of environment, diet or therapies on the aging process and the development of age-related diseases. This clock could therefore find wide application in aging research. Since BiT age is based purely on gene activity, it can basically be applied to any organism,’ Schumacher explained.


Reference: Meyer, D.H. and Schumacher, B. (2021), BiT age: A transcriptome‐based aging clock near the theoretical limit of accuracy. Aging Cell e13320. https://doi.org/10.1111/acel.13320


Provided by University of Cologne

Prenatal Thyroid Hormones Influence ‘Biological Age’ At Birth (Biology)

The environment provided by the mother during embryo development has major consequences on later-life health and lifespan. This can arise through effects on cellular ageing which is often estimated with the length of telomeres. Telomeres are the protective end caps of chromosomes and their length is a marker of ‘biological age’.

Flycatcher egg being illuminated in order to inject thyroid hormones specifically into the egg yolk. ©Tom Sarraude

While telomeres normally shorten with age, short telomeres at a given age predict higher disease and mortality risks. Prenatal exposure to maternal stress hormones as well as instability during embryo development have previously been found to result in short telomeres, i.e. accelerated cellular ageing.

A new study funded by the Academy of Finland and the Turku Collegium for Science and Medicine manipulated prenatal exposure to maternal thyroid hormones using egg injection in an avian model.

“The telomere biology of humans is closer to the telomere biology of birds than those of traditional laboratory models. In both human and birds, telomere length is measured in a minimally-invasive way from small blood samples,” says Collegium Researcher Antoine Stier from the University of Turku (Finland), the main author of the research article.

While authors of the study had reasons to expect shorter telomeres in chicks born from eggs injected with thyroid hormones, they were quite surprised to find that those chicks actually exhibited longer telomeres right after birth.

“Based on the natural decline of telomere length observed with age in the same collared flycatcher population, we estimated that chicks hatching from thyroid hormones injected eggs were approximately 4 years ‘younger at birth’ than chicks hatched from control eggs,” adds Collegium Researcher Suvi Ruuskanen.

Although the molecular mechanisms underlying such effects remain to be discovered, the new findings suggest that prenatal thyroid hormones might have a role in setting the ‘biological age’ at birth.

“Considering the interest and controversies surrounding gene therapy trials in humans to elongate telomeres as an anti-ageing therapy, this discovery opens potential avenues to better understand the influence of telomere elongation in animal models,” Stier says.

The study was conducted on a long-term monitored population of wild collared flycatcher breeding in Gotland island, and relied on extensive collaborations with the University of Uppsala (Sweden), Lyon, Glasgow and Aberdeen.

References: Antoine Stier , Bin-Yan Hsu , Coline Marciau , Blandine Doligez , Lars Gustafsson , Pierre Bize and Suvi Ruuskanen, “Born to be young? Prenatal thyroid hormones increase early-life telomere length in wild collared flycatcher”, Royal Society Publishing, 2020. doi: https://doi.org/10.1098/rsbl.2020.0364 https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0364

Provided by University of Turku