Vacuolar control of subcellular cation distribution is a key parameter in the adaptation of Debaryomyces hansenii to high salt concentrations.

Debaryomyces hansenii is a halotolerant and Na+-includer yeast that can be isolated from different food and low-water activity products. It has also been defined as a marine-occurring yeast but key aspects for this salt tolerant behavior are far from being understood. Here, we searched for clues helping to elucidate the basis of this ability. Our results on growth, Rb+ transport, total K+ and Na+ content and vacuolar fragmentation are compatible with a yeast species adapted to cope with salt stress. On the other hand, we confirmed the existence of D. hansenii strategies that are generally observed in sensitive organisms, such as the production of glycerol as a compatible solute and the efficient vacuolar sequestration of Na+. We propose a striking role of D. hansenii vacuoles in the maintenance of constant cytosolic K+ values, even in the presence of extracellular Na+ concentration values more than two orders of magnitude higher than extracellular K+. Finally, the ability to deal with cytosolic Na+ levels significantly higher than those found in S. cerevisiae, shows the existence of important and specific salt tolerance mechanisms and determinants in D. hansenii.

Dorfman-Chanarin syndrome.

A four-year-old girl was brought to the dermatology outpatient department with scaling all over the body since birth. She had history of episodic vomiting and abdominal distension. A dermatological diagnosis of lamellar ichthyosis was made. Abdominal examination revealed a nontender hepatomegaly, fatty liver on ultrasonography and deranged liver function tests. Peripheral blood smear showed lipid vacuoles in the granulocytes consistent with Jordans' anomaly. Similar lipid vacuoles were seen in the basal layer in skin biopsy. An inflammatory infiltrate, moderate fibrosis in the portal tract and diffuse severe fatty change in hepatocytes were seen in liver biopsy. The patient was diagnosed as a case of Dorfman-Chanarin syndrome.

Translocation of zinc from vacuole to nucleus during yeast meiosis.

A novel staining procedure employing the UV fluorochrome DAPI (4',6-diamidino-2-phenylindole X 2HCl) and dithizone (diphenylthiocarbazone) was developed for microcytochemical determination of sites of zinc localization in Saccharomyces cerevisiae Hansen. In vegetative cells vacuolar polyphosphate bodies stained with dithizone, whereas in sporulating cells nucleoli and centriolar plaques were dithizone-positive. Hence, dithizone not only permitted localization of zinc but also indicated zinc translocation from vacuolar to nuclear compartments during differentiation from the vegetative to sporulated state.