Hydrogen peroxide-induced oxidative damages in Schizosaccharomyces pombe

Ascorbic acid supplementation suppresses cadmium-derived alterations in the fission yeast Schizosaccharomyces pombe

Cadmium (Cd) a highly toxic environmental pollutant, that does not have any physiological function in the organism, represents a great concern for human health as it can be easily transported from its environmental sources to the food chain. Food, water, and air are the major sources of Cd exposure to the population. Cd-mediated impairments of the basic cellular properties largely depend on its ability to enhance the formation of reactive oxygen species (ROS) and thus triggers oxidative stress to the cell. With the use of fission yeast Schizosaccharomyces pombe (S. pombe) as the model organism, we have analyzed the impact of Cd on the cell growth intensity, as it represents the fundamental feature of all living organisms. Cells were incubated with different Cd concentrations for 3, 6, and 9 hours to investigate the effect of Cd on cell growth in a time and dose-dependent manner. Further possible Cd-derived alterations, as the peroxidation of membrane lipids or the functional impairment of the enzymatic antioxidant protection mechanisms, were investigated by determination of the MDA content and via catalase (CAT) activity detection. Moreover, ascorbic acid (AsA) pre-treatment was subjected to investigate the assumed positive effect of AsA against Cd toxicity. We show here on one hand that cells suffer under the influence of Cd, but on the other hand, they substantially profit from AsA supplementation. Because S. pombe is known to shares many molecular, and biochemical similarities with higher organisms, the effect of AsA in cadmium toxicity elimination might be expected to a similar extent also in other cell types.

Ascorbic acid mitigates cadmium-induced stress, and contributes to ionome stabilization in fission yeast

Cadmium is a highly toxic environmental pollutant which through enhancement of reactive oxygen species (ROS) production triggers oxidative stress to the cell. Cell growth, a fundamental feature of all living organisms is closely connected to the cell shape and homeostasis. As these processes largely depend on cell fitness status and environmental conditions we have analyzed, the impact of different cadmium concentrations and the effect of ascorbic acid (ascorbate, AsA) supplementation on cell growth parameters, cell morphology, and ionome balance maintenance in Schizosaccharomyces pombe. We show that cadmium causes membrane lipid peroxidation resulting in cell shape alterations leading to growth impairment and through mineral elements disequilibrium affects ionome homeostasis in a dose- and time-dependent manner. AsA recognized as one of the most prominent antioxidants, when overdosed, displays considerable pro-oxidant activity, though precise dosing of its supplementation is desired. We present here that AsA under efficacious concentration largely improves cell condition affected by cadmium. Although, we clearly demonstrate the beneficial feature of AsA, further studies are required to fully understand its protective nature on cell homeostasis maintenance under conditions of the broken environment.

Cadmium-Induced Cell Homeostasis Impairment is Suppressed by the Tor1 Deficiency in Fission Yeast

Cadmium has no known physiological function in the body; however, its adverse effects are associated with cancer and many types of organ system damage. Although much has been shown about Cd toxicity, the underlying mechanisms of its responses to the organism remain unclear. In this study, the role of Tor1, a catalytic subunit of the target of rapamycin complex 2 (TORC2), in Cd-mediated effects on cell proliferation, the antioxidant system, morphology, and ionome balance was investigated in the eukaryotic model organism Schizosaccharomyces pombe. Surprisingly, spectrophotometric and biochemical analyses revealed that the growth rate conditions and antioxidant defense mechanisms are considerably better in cells lacking the Tor1 signaling. The malondialdehyde (MDA) content of Tor1-deficient cells upon Cd treatment represents approximately half of the wild-type content. The microscopic determination of the cell morphological parameters indicates the role for Tor1 in cell shape maintenance. The ion content, determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), showed that the Cd uptake potency was markedly lower in Tor1-depleted compared to wild-type cells. Conclusively, we show that the cadmium-mediated cell impairments in the fission yeast significantly depend on the Tor1 signaling. Additionally, the data presented here suggest the yet-undefined role of Tor1 in the transport of ions.

Increase in antioxidant gene transcripts, stress tolerance and biocontrol efficacy of Candida oleophila following sublethal oxidative stress exposure

A pretreatment of the yeast, Candida oleophila, with 5 mM H(2)O(2) for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H(2)O(2)), high temperature (40 °C), and low pH (pH 4). Compared with non-stress-adapted yeast cells, stress-adapted cells exhibited better control of apple fruit infections by Penicillium expansum and Botrytis cinerea and had initially higher growth rates in apple wounds. Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semiquantitative reverse transcription-PCR. Seven antioxidant genes were upregulated. The elevated expression of these genes was associated with less accumulation of reactive oxygen species and a lower level of protein and lipid oxidation under subsequent stresses. These data support the premise that induction of abiotic stress tolerance in biocontrol yeast can improve biocontrol efficacy by upregulation of genes involved in the amelioration of oxidative stress.