Yashin AI et al. (2001) Mech Ageing Dev "Ageing and survival after different doses of heat shock: the results of analysis of data from stress experiments with the nematode worm Caenorhabditis elegans."

Boyko SI, Johnson TE, Yashin AI, Novoseltsev VN, Cypser JR, Michalski AI

[Mech Ageing Dev, 2001]

Stress experiments performed on a population of sterilised nematode worms (Caenorhabditis elegans) show a clear hormesis effect after short exposure and clear debilitation effects after long exposure to heat shock. An intermediate duration of exposure results in a mixture of these two effects. In this latter case the survival curves for populations in the stress and control groups intersect. In this paper we develop an adaptation model of stress and apply it to the analysis of survival data from three such stress experiments. We show that the model can be used to explain empirical age-patterns of mortality and survival observed in these experiments. We discuss possible biological mechanisms involved in stress response and directions for further research.

Yashin AI et al. (2002) J Gerontol A Biol Sci Med Sci "Heat shock changes the heterogeneity distribution in populations of Caenorhabditis elegans: does it tell us anything about the biological mechanism of stress response?"

Yashin AI, Michalski AI, Boyko SI, Johnson TE, Cypser JW, Novoseltsev VN

[J Gerontol A Biol Sci Med Sci, 2002]

In this paper we analyze Survival data of populations of sterilized nematodes. Caenorhabditis elegans. exposed to heat shocks of different duration at the beginning of their adult lives. There are clear hormesis effects after short exposure to heat and clear debilitation effects after long exposure. Intermediate durations result in a mixture of these two effects. In this latter case. the survival curves for the control and experimental populations intersect. We show that observed effects may be explained by using a model of discrete heterogeneity. According to this model. each Population of worms in the experiment is a mixture of subcohorts of frail, normal. and robust individuals: exposure to heat changes the initial proportion of worms in the subcohorts (heterogeneity distribution): and these changes depend on the duration Of exposure. In other words, exposure to heat does not influence mortality rates (survival functions) in the subcohorts but does cause individuals to move from one subcohort to another. In a biological interpretation of this finding we hypothesize that. when coping with stress. the organisms of storms use several lines of defense. Switching these lines of ana off in response to stress in individual organisms Generates the spectrum of observed survival effects at the population level. We discuss possible molecular biological mechanisms of stress response and directions for further research.

Zhang J et al. (2022) Environ Toxicol Pharmacol "Reproductive toxicities of ofloxacin and norfloxacin on Caenorhabditis elegans with multi-generational oscillatory effects and trans-generational residual influences."

Yu Z, Zheng Y, Zhang J

[Environ Toxicol Pharmacol, 2022]

The reproductive toxicities over generations are essential to assess the long-term impacts environmental fluoroquinolone antibiotics (FQs). In the present study, the multi-generational effects of ofloxacin (OFL) and norfloxacin (NOR) on reproduction were studied on Caenorhabditis elegans from 9 successive generations (F1-F9). Results showed that OFL showed no effects in F1, stimulation in F2 to F4, and inhibition F5 to F9. The effects of NOR also showed oscillation between stimulation and inhibition across generations. Further biochemical analysis demonstrated that the reproductive toxicities of OFL and NOR were more closely connected with total cholesterol (TCHO), progesterone (P) and testosterone (T), than major sperm protein (MSP) and vitellogenin (Vn). Moreover, OFL and NOR also showed significant trans-generational reproductive toxicities in T4 and T4', the great-grand-daughter of F1 and F9. Differences between T4 and T4' and between OFL and NOR, indicated influences of multi-generational exposure and urged more exploration on different mechanisms between FQs.

Wang L et al. (2022) Sci Total Environ "Hormone-mediated multi- and trans-generational reproductive toxicities of 1-ethyl-3-methylimidazolium hexafluorophosphate on Caenorhabditis elegans."

Wu D, Wang L, Yu Z, Huang S, Zhang J

[Sci Total Environ, 2022]

Ionic liquids (ILs) are emergent pollutants and their reproductive toxicities show hormesis, earning attentions on their environmental risk. Yet, their reproductive effects over generations and the mechanisms were seldom explored. In the present study, the reproductive effects of 1-ethyl-3-methylimidazolium hexafluorophosphate ([C₂mim]PF₆) on Caenorhabditis elegans were measured in 11 continuously exposed generations (F1 to F11) to explore the multi-generational effects, and also in the non-exposed generations of F1 and F11 (i.e., their great-grand-daughters, T4 and T4') to explore the trans-generational effects. In multi-generational reproductive effects, there were concentration-dependent hormetic effects with hazard-benefit alteration between low and high concentrations (e.g., in F3). There were also generation-dependent hormetic effects with hazard-benefit alterations over generations (e.g., between F4 and F5, between F8 and F9, and between F10 and F11). Meanwhile, the results also showed benefit-hazard alteration between F2 and F3, between F6 and F7, and between F9 and F10. Trans-generational effects showed common inhibitions in T4 and T4' at both low and high concentrations. In the biochemical analysis, hormones and hormone-like substances including progesterone (P), estradiol (E2), prostaglandin (PG) and testosterone (T) showed multi- and trans-generational changes with inhibition and stimulation, which contributed to the reproductive outcomes in each generation. Such contribution was also observed in the hormones' precursor cholesterol and the proteins that are essential for reproduction including vitellogenin (Vn) and major sperm protein (MSP). Moreover, the biochemicals showed significant involvement in the connection among generations. Furthermore, the multi- and trans-generational effects of [C₂mim]PF₆ and histidine showed similar modes of actions despite some differences, implying the contribution of their shared imidazole structure.