ROGERSIOMYCES,A NEW GENUS IN THE FILOBASIDIACEAE (HOMOBASIDIOMYCETES) FROM AN AQUATIC HABITAT

Rogersiomyces okefenokeensis gen. et sp. n. is a Homobasidiomycete described in the Filobas-idiaceae. It is characterized by gymnocarpous basidiocarps composed of fasciculate or loose synnematous holobasidia. The basidia are characteristically obclavate with prominent, truncate sterigmata and function as apobasidia. The basidiospores are borne symmetrically, are nonapiculate, and germinate directly to form mycelium or occasionally by repetition. Some examples are presented to illustrate an apparent correlation of apobasidia with an adaptation to aquatic habitats.     

Storage behavior of Typha latifolia pollen at low water contents: Interpretation on the basis of water activity and glass concepts

Germplasm must be stored under optimal conditions to maximize longevity and efficiently maintain genetic resources. In order to identify optimal storage conditions, we investigated the effects of temperature (−5 to 45°C) and water content (<0.17 g H₂O g⁻¹ dry weight) on longevity of Typha latifolia L. pollen. Longevity was highest at water contents corresponding to storage relative humidity (RH) of 11‐15% which corresponded to the shoulder of water sorption isotherms. Also coinciding with this shoulder were abrupt changes in heat capacity of water present in the pollen. Consistent with changes in isotherms with temperature and the concept of critical RH for storage, optimum water contents increased with decreasing temperature. An attempt was made to explain the aging behavior according to the glass concept. The water content‐temperature combinations of optimal storage were found to be below the glass transition curve, indicating that optimum storage conditions are achieved when intracellular glasses are present. We also found a change in activation energy of aging in Arrhenius plots around T_g, demonstrating a change in aging kinetics when the glassy state is lost. We concluL that T_g curves cannot be used solely to predict precise conditions of optimum storage, but might be useful for predictions of storage longevity above optimum water contents. The data imply that too much drying reduces longevity and should be avoided, particularly when cryogenic storage is considered.     

Theoretical models of cellular dielectrophoresis

Dielectrophoresis, the motion of neutral particles induced by a non-uniform electric field, is useful in separating and comparing single-celled organisms. The rate of dielectrophoretic collection in a region of higher field, called the “yield”, depends strongly upon the physiological state of the organism, upon the frequency of the field, and upon the conductivity of the suspending medium. The resulting yield spectrum is complex.     

Prevention by uncouplers of lipophilic chelator inhibition at three sites of mitochondrial electron transport

Inhibition of coupled electron transport in mitochondrial cristae by hydrophobic chelators such as bathophenanthroline is partially prevented by uncoupling agents such as carbonylcyanide-m-chlorophenyl hydrazone. Reversal of inhibition is observed in all three sections of the electron transport chain where energy coupling occurs. Sites inhibited by hydrophilic bathophenanthroline sulfonate or orthophenanthroline do not show uncoupler relief of inhibition. We conclude that a buried non-heme iron or copper protein is closely associated with each energy coupling site.