Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth

Abstract

In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed 15N-enriched algae (0.4–5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies.

Isotope effect of 13C‑enriched testosterone on human cells

“…It is considered that the enrichment of a heavy isotope attenuates the biochemical reaction rate and delays the growth of an organism due to the kinetic isotope effect (2,(32)(33)(34). This view was supported by the findings of the present study using 13 C-enriched testosterone at physiological concentrations; 13 C-enriched testosterone on the alkaline phosphatase level of human osteoblasts.…”

Age-related decline in metabolite heavy isotope content in rodent organs

“…We found an overall trend of decline, which occurred when yeast cells get old, and elevating the HIC for hydrogen through heavy water feeding extended yeast lifespan by 84%. Our observation echoed the results of a previous study, which demonstrated that transient heavy water treatment extended lifespan in fruit flies, and more recently, another study showing that 15 N-enriched food extended lifespan in rotifers (Gorokhova, 2017;Hammel et al, 2013). These studies suggest that HIC elevation may produce a universal prolongevity effect, but before we could address this directly in mammalian animals, it is still unclear whether an overall HIC decline exists in mammals and for practical reason, whether HIC manipulation would promote longevity in model animals that are closer to human in biology.…”

Observations on Biological Effects of Carbon-13, Based on the Effects of 13C-Testosterone on Growth of Human Osteoblasts, Human Aortic Endothelial Cells, and Human Umbilical Vein Endothelial Cells in Vitro

“…It has been generally believed that enrichment of heavy isotope slow down the biochemical reaction rate and retard the growth of organism because of kinetic isotope effect [24][25][26][27][28]. This common view was supported by only a part of our findings.…”