Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations

Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker''s yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels.     

Nitric Oxide as a Key Gasotransmitter in Fruit Postharvest: An Overview

Currently, the field of postharvest technology is a growing research area of particular interest since the increase in world population and the need to satisfy its nutritional requirements. These aspects establish a demand to produce fruits with high market quality while minimizing the losses from production to consumption stages. In the past few years, nitric oxide (NO) has emerged as a novel gasotransmitter to improve fruit postharvest shelf-life, owing to its influence on physiological processes (including fruit ripening) and on acclimation responses to stress conditions. In this review, we summarize some of the research related to the effects of NO exposure on different fruits with the aim to extend postharvest shelf-life and quality. The protection against chilling injury and postharvest diseases are addressed. The mechanisms of NO action and its interactions with other phytohormones are analyzed. Finally, the potential use of NO donors (and other strategies destined to enhance its levels) with a technological scope is also discussed.