Unusual fungal niches.

Fungi are found in all aerobic ecosystems, colonizing a diversity of substrates and performing a wide diversity of functions, some of which are not well understood. Many spices of fungi are cosmopolitan and generalists or habitats. Unusual fungal niches are habitats where extreme conditions would be expected to prevent the development of a mycobiota. In this review we describe five unusual fungal habitats in which fungi occupy poorly understood niches: Antarctic dry valleys, high Arctic glaciers, salt flats and salterns, hypersaline microbial mats and plant trichomes. Yeasts, black yeast-like fungi, melanized filamentous species as well as representatives of Aspergillus and Penicillium seem to be dominant among the mycobiota adapted to cold and saline niches. Plant trichomes appear to be a taxa. The advent of new sequencing technologies is helping to elucidate the microbial diversity in many ecosystems, but more studies are needed to document the functional role of fungi in the microbial communities thriving in these unusual environments.

Periconia variicolor sp. nov., a new species from Puerto Rico.

Periconia variicolor was isolated from water of an evaporation pond used for salt production on the southwestern coast of Puerto Rico. On the basis of cultural and morphological characteristics and ITS sequence it is describe as a new species of Periconia.

Subchronic toxicity study of 1,4-dithiane in the rat.

In a 90-day study, CD strain rats were dosed with 1,4-dithiane by daily gavage at 0, 105, 210, and 420 mg/kg/day (30 rats/sex/dose) in order to calculate a suggested drinking water criterion. No overt toxicity, treatment-related mortality, or ophthalmologic changes were found. Treatment-related decreases were found in female amylase, sorbitol dehydrogenase, and reticulocyte count, and in LDH 1 in both sexes, in LDH 3 in the males, and in LDH 5 in both sexes. Treatment-related increases were found in female liver and in male kidney and male thymus weight. A treatment-related decrease in female brain weight was also found. Significant changes in organ weight of dosed animals compared to control organ weight were observed at the 105 mg/kg/day dose in the spleen of both sexes, female brain, and the male kidneys. Three organs showed compound-related anatomic changes: nose, liver, and kidney. Anisotrophic crystals of undetermined chemical composition were deposited in the olfactory nasal mucosa of both sexes. These crystals were not composed of 1,4-dithiane because 1,4-dithiane is very soluble in ethanol and would not have been present after the slide preparation process. The crystals were present in similar amounts in both sexes of the high and intermediate dose groups. In the low dose group, however, the crystals were present in greater amounts in the females. Crystals were not observed in the control animals. The other treatment-related anatomic abnormalities were eosinophilic cytoplasmic granulation of the convoluted renal tubule cells in the high dose males and minimal hypertrophy of the centrilobular region of the liver in the high dose females. The animal no-observed-effect-level was 105 mg/kg/day. This study reports a novel form of toxicity (deposition of anisotrophic crystals in the olfactory mucosa) from 1,4-dithiane administered by gavage. The chemical composition of the crystals and the absorption, distribution, metabolism, and excretion of 1,4-dithiane are unknown at present.