Aging extension and modifications of lipid metabolism in the monogonont rotifer Brachionus koreanus under chronic caloric restriction

Abstract

To examine the interrelationship of aging extension and modification of lipid metabolism under chronic caloric restriction (CCR; reduced concentration of the green algae Tetraselmis suecica) in the monogonont rotifer Brachionus koreanus, we assessed life cycle parameters, fatty acid composition, and expression of sirtuin and genes related to lipid metabolism. B. koreanus in the 5% T. suecica group showed an increased life span but decreased reproduction. Based on this finding, we chose 5% T. suecica for further experiments and compared the data with those for 100% T. suecica. Upregulation of sirtuin gene expression was observed under CCR. In addition, despite the reduction in the amount of total fatty acid (FA) and the area of triacylglycerol, increases in the ratios of saturated fatty acid and monounsaturated fatty acid (MUFA) to total FA in 5%-exposed B. koreanus were observed. Furthermore, mRNA expression analysis confirmed that CCR promoted the synthesis of MUFA through Δ9 desaturase. Moreover, expression of the docosahexaenoic acid (DHA) synthesizing gene Δ4 desaturase was also upregulated, together with DHA content. These data suggest that CCR modified protein acetylation and lipid metabolism, leading to a decrease in reproduction and consequently resulting in life span extension.The energy trade-off between life span and reproduction is commonly observed in most animal taxa 1 . This phenomenon can be affected by various abiotic and biotic factors, such as temperature 2,3 , pH 4 , and metabolic changes 5 . Among them, chronic caloric restriction (CCR) is a well-known regulator leading to an energy trade-off in various organisms such as mice 6-8 , the grasshopper Romalea microptera 9 , the nematode Caenorhabditis elegans 10 , and the rotifer Brachionus manjavacas 11 . Based on previous findings, a simple hypothesis to explain this phenomenon is that this is one of the strategies organisms use to overcome unfavorable changes in their surrounding environment.Many studies on the mechanisms of prolonging life span have focused on protein deacetylase. From yeast to human, life span is regulated by protein modification 12,13 . In particular, the gene encoding sirtuin, one of the protein deacetylases, is a well-known marker of life span regulation 14 . Sirtuin genes were initially identified as transcription-silencing protein deacetylases in yeast. Calorie restriction was shown to extend life span through upregulation of yeast sirtuin genes 15,16 . In addition, upregulation of sirtuin2 was reported to extend life span in the fruit fly Drosophila melanogaster 17 , although there is still some controversy regarding this finding 18 . In mammals, seven sirtuin genes have been identified, and sirtuin1 was found to have a similar function to sirtuin2 in yeast in terms of longevity 19 . Therefore, study of the function of sirtuin genes is important in relation to life span.

Tributyltin Affects Retinoid X Receptor-Mediated Lipid Metabolism in the Marine Rotifer Brachionus koreanus

“…However, at lower concentrations (0.1, 0.5, and 1 μg/L), TBT did not induce significant changes compared to the control. In general, lifespan and reproduction show an inverse relationship in rotifers under moderately toxic conditions, which aligns with the costs of reproduction hypothesis. − As one of the survival strategies, rotifers extended their lifespan under moderate toxic environment for future reproduction. However, in this study, severe toxic effects were observed only at 5 μg/L TBT, indicating that the 5 μg/L TBT exposure condition is so toxic that B.…”

Enhancement of Intracellular Accumulation of Copper by Biogenesis of Lipid Droplets in Saccharomyces cerevisiae Revealed by Transcriptomic Analysis

“…65,66 However, the actual roles of HSP12 and POR1 in the copper resistance and copper uptake ability of S. cerevisiae are yet not revealed. A lower level of intracellular copper and the in turn upregulation of metal transporters were reported in S. cerevisiae under the calorie restriction, 67 while reduction in the triacylglycerol level was found in the monogonont rotifer Brachionus koreanus under the chronic caloric restriction, 68 implying the possible connection of lipid metabolism with copper metabolism. In this study, no obvious differences in copper resistance and transcription levels of HSP12 or POR1 were observed between the mutant H247 and the reference strain Cu-5.…”

Ultraviolet irradiation increases size of the first clutch but decreases longevity in a marine copepod

“…Although diet may have had an influence on the ability of female copepods to defend against harmful UV irradiation in our study, it is unlikely that the observed effects herein are due to diet, provided that all females were supplied ad libitum access to the same algae throughout the study (see Lee et al, 2018 for how caloric restriction may influence the life history of aquatic organisms). Furthermore, UV radiation is necessary for endogenous vitamin D production; an induced increase in vitamin D via UV irradiation in Daphnia has been shown to increase fecundity (Connelly et al, 2015).…”