Zinc and cadmium contamination in an Avicennia schaueriana mangrove environment: Mass balance and tissue distribution.

The leachate pond of a Zn processing plant in Rio de Janeiro, Brazil, released Zn and Cd into a mangrove during three decades. Soil, root, stems, leaves and phloem bark samples of Avicenna schaueriana from the mangrove were collected and analyzed. Zn and Cd levels were measured by atomic absorption and were much more concentrated in soil at 76 kg/ha and 424 kg/ha respectively than in the trees (272.

Tremella saccharicola f.a., sp. nov., a novel tremellaceous yeast species isolated from tropical regions.

Ten strains representing a single anamorphic novel yeast species were isolated from the external surface (DMKU-SP23 and DMKU-SP40) and tissue (DMKU-SE89, DMKU-SE99, DMKU-SE100 and DMKU-SE147) of sugarcane leaves in Thailand, and phylloplane (IMUFRJR 52034) and rhizoplane (IMUFRJ 52036 and 52037) of sugarcane and associated soil (IMUFRJ 52035) in Brazil. These strains showed zero to two nucleotide substitutions in the sequences of the D1/D2 region of the LSU rRNA gene and zero to three nucleotide substitutions in the internal transcribed spacer (ITS) region. Tremella globispora was the most closely related species, but with 1.

Force field development phase II: Relaxation of physics-based criteria… or inclusion of more rigorous physics into the representation of molecular energetics.

In the previous paper, we reviewed the origins of energy based calculations, and the early science of FF development. The initial efforts spanning the period from roughly the early 1970s to the mid to late 1990s saw the development of methodologies and philosophies of the derivation of FFs. The use of Cartesian coordinates, derivation of the H-bond potential, different functional forms including diagonal quadratic expressions, coupled valence FFs, functional form of combination rules, and out of plane angles, were all investigated in this period.

Biomolecular force fields: where have we been, where are we now, where do we need to go and how do we get there?

In this perspective, we review the theory and methodology of the derivation of force fields (FFs), and their validity, for molecular simulations, from their inception in the second half of the twentieth century to the improved representations at the end of the century. We examine the representations of the physics embodied in various force fields, their accuracy and deficiencies. The early days in the 1950s and 60s saw FFs first introduced to analyze vibrational spectra.

Diversity of Quaternary Structures Regulates Nuclear Receptor Activities.

Nuclear receptors (NRs) form homo- and/or heterodimers as central scaffolds of multiprotein complexes, which activate or repress gene transcription to regulate development, homeostasis, and metabolism. Recent studies on NR quaternary structure reveal novel mechanisms of receptor dimerization, the existence of tetrameric chromatin-bound NRs, and previously unanticipated protein-protein/protein-DNA interactions.