Monoorganobismuth(III) dithiocarboxylates: Synthesis, structures and their utility as molecular precursors for the preparation of Bi2S3 films and nanocrystals

Synthesis of a series of monoorganobismuth dithiocarboxylate complexes, [RBi(S₂CAr)₂] (R = Me, Ph, tol; Ar = Ph, tol), has been reported. They have been characterized by elemental analyses and spectroscopic methods. Molecular structures of [RBi(S₂Ctol)₂] (R = Me or Ph) have been established by single crystal X-ray diffraction studies. The bismuth atom in these complexes adopts a square pyramidal configuration with the R group at the apical position. In the solid state, these complexes show supra-molecular association devoid of Bi?S secondary interactions. Thermolysis of [RBi(S₂Ctol)₂] (R = Me or Ph) in refluxing diphenylether yielded Bi₂S₃ nanocrystals which were characterized by XRD, EDAX and SEM. The complex [PhBi(S₂Ctol)₂] has been employed for deposition of thin films of Bi₂S₃ by AACVD.     

Human ClC-3 is not the swelling-activated chloride channel involved in cell volume regulation

Volume regulation is essential for normal cell function. A key component of the cells' response to volume changes is the activation of a channel, which elicits characteristic chloride currents (I(Cl, Swell)). The molecular identity of this channel has been controversial. Most recently, ClC-3, a protein highly homologous to the ClC-4 and ClC-5 channel proteins, has been proposed as being responsible for I(Cl, Swell). Subsequently, however, other reports have suggested that ClC-3 may generate chloride currents with characteristics clearly distinct from I(Cl, Swell). Significantly different tissue distributions for ClC-3 have also been reported, and it has been suggested that two isoforms of ClC-3 may be expressed with differing functions. In this study we generated a series of cell lines expressing variants of ClC-3 to rigorously address the question of whether or not ClC-3 is responsible for I(Cl, Swell). The data demonstrate that ClC-3 is not responsible for I(Cl, Swell) and has no role in regulatory volume decrease, furthermore, ClC-3 is not activated by intracellular calcium and fails to elicit chloride currents under any conditions tested. Expression of ClC-3 was shown to be relatively tissue-specific, with high levels in the central nervous system and kidney, and in contrast to previous reports, is essentially absent from heart. This distribution is also inconsistent with the previous proposed role in cell volume regulation.     

Cell volume regulation and swelling-activated chloride channels

Maintenance of a constant volume is essential for normal cell function. Following cell swelling, as a consequence of reduction of extracellular osmolarity or increase of intracellular content of osmolytes, animal cells are able to restore their original volume by activation of potassium and chloride conductances. The loss of these ions, followed passively by water, is responsible for the homeostatic response called regulatory volume decrease (RVD). Activation of a chloride conductance upon cell swelling is a key step in RVD. Several proteins have been proposed as candidates for this chloride conductance. The status of the field is reviewed, with particular emphasis on ClC-3, a member of the ClC family which has been recently proposed as the chloride channel involved in cell volume regulation.     

Conservation of the Ustilago maydis effector See1 in related smuts

Ustilago maydis is a biotrophic fungus that induces formation of tumors in maize (Zea mays L). In a recent study we identified See1 (Seedling efficient effector 1) as an U. maydis organ-specific effector required for tumor formation in leaves. See1 is required for U. maydis induced reactivation of plant DNA synthesis during leaf tumor progression. The protein is secreted from biotrophic hyphae and localizes to the cytoplasm and nucleus of plant cell. See1 interacts with maize SGT1, a cell cycle and immune regulator, interfering with its MAPK-triggered phosphorylation. Here, we present new data on the conservation of See1 in other closely related smuts and experimental data on the functionality of See1 ortholog in Ustilago hordei, the causal agent of barley covered smut disease.     

Mannitol production from glycerol by resting cells of Candida magnoliae

Production of mannitol from glycerol by resting cells of Candida magnoliae under aerobic condition was investigated. The resting cells were suspended in aqueous solution of glycerol in Erlenmeyer flasks and incubated on rotary shaker. The samples were analyzed by ion exclusion–HPLC equipped with refractive index and UV detector. The resting cells of C. magnoliae produced mannitol from fructose, sucrose and glycerol but not from glucose. Addition of yeast extract and/or potassium phosphate to the glycerol solution adversely affected its conversion to mannitol. The conversion of glycerol to mannitol was dependent on oxygen availability. Using resting cells, the yield of mannitol was as high as 45%. This is probably the first report of conversion of glycerol to mannitol by osmophilic yeast.     

Ecological impacts of a widespread frost event following early spring leaf‐out

In the spring of 2010, temperatures averaged ~3 °C above the long‐term mean (March–May) across the northeastern United States. However, in mid‐to‐late spring, much of this region experienced a severe frost event. The spring of 2010 therefore provides a case study on how future spring temperature extremes may affect northeastern forest ecosystems. We assessed the response of three northern hardwood tree species (sugar maple, American beech, yellow birch) to these anomalous temperature patterns using several different data sources and addressed four main questions: (1) Along an elevational gradient, how was each species affected by the late spring frost? (2) How did differences in phenological growth strategy influence their response? (3) How did the late spring frost affect ecosystem productivity within the study domain? (4) What are the potential long‐term impacts of spring frost events on forest community ecology? Our results show that all species exhibited early leaf development triggered by the warm spring. However, yellow birch and American beech have more conservative growth strategies and were largely unaffected by the late spring frost. In contrast, sugar maples responded strongly to warmer temperatures and experienced widespread frost damage that resulted in leaf loss and delayed canopy development. Late spring frost events may therefore provide a competitive advantage for yellow birch and American beech at the expense of sugar maple. Results from satellite remote sensing confirm that frost damage was widespread throughout the region at higher elevations (>500 m). The frost event is estimated to have reduced gross ecosystem productivity by 70–153 g C m^?2, or 7–14% of the annual gross productivity (1061 ± 82 g C m^?2) across 8753 km² of high‐elevation forest. We conclude that frost events following leaf out, which are expected to become more common with climate change, may influence both forest composition and ecosystem productivity.