Winter desiccation and rapid changes in the live fuel moisture content of Calluna vulgaris

<p>Background: Dramatic reductions in early-spring Calluna vulgaris moisture content have been linked to extreme fire hazard and plant die-back.</p> <p>Aims: To investigate spatial and temporal variation in the fuel moisture content of Calluna vulgaris.</p> <p>Methods: Calluna vulgaris plants were sampled in different sites and seasons to examine vertical profiles in moisture content. Live moisture content was monitored throughout autumn 2003 and spring 2004. Changes were compared to trends in temperature, soil resistance and rainfall. The effect of exposure was examined by comparing shoot moisture content in sheltered and exposed locations.</p> <p>Results: Significant spatial and temporal variation in moisture content was observed. In spring rapid fluctuations in moisture coincided with periods of dry weather, low temperatures and frozen ground. Shoots from exposed locations had significantly lower moisture content when the ground was frozen.</p> <p>Conclusions: Significant declines in the live fuel moisture content of Calluna vulgaris are associated with physiological drought caused by cold, clear conditions and frozen ground. Over-winter damage to leaf cuticles reduces the ability of the plant to regulate water loss. Changes in moisture content can be rapid, and managers should be aware of the potential for extreme fire behaviour.</p&gt

The Xenoestrogen Bisphenol A Inhibits Postembryonic Vertebrate Development by Antagonizing Gene Regulation by Thyroid Hormone

Bisphenol A (BPA), a chemical widely used to manufacture plastics, is estrogenic and capable of disrupting sex differentiation. However, recent in vitro studies have shown that BPA can also antagonize T3 activation of the T3 receptor. The difficulty in studying uterus-enclosed mammalian embryos has hampered the analysis on the direct effects of BPA during vertebrate development. This study proposed to identify critical T3 pathways that may be disrupted by BPA based on molecular analysis in vivo. Because amphibian metamorphosis requires T3 and encompasses the postembryonic period in mammals when T3 action is most critical, we used this unique model for studying the effect of BPA on T3-dependent vertebrate development at both the morphological and molecular levels. After 4 d of exposure, BPA inhibited T3-induced intestinal remodeling in premetamorphic Xenopus laevis tadpoles. Importantly, microarray analysis revealed that BPA antagonized the regulation of most T3-response genes, thereby explaining the inhibitory effect of BPA on metamorphosis. Surprisingly, most of the genes affected by BPA in the presence of T3 were T3-response genes, suggesting that BPA predominantly affected T3-signaling pathways during metamorphosis. Our finding that this endocrine disruptor, well known for its estrogenic activity in vitro, functions to inhibit T3 pathways to affect vertebrate development in vivo and thus not only provides a mechanism for the likely deleterious effects of BPA on human development but also demonstrates the importance of studying endocrine disruption in a developmental context in vivo

Fire! : An Exhibition of 100 Texas Artists

Surls introduces the Fire project and its genesis. Includes statements by most of the 100 exhibiting artists

BHLH-PAS proteins in cancer

Mammalian basic HLH (helix–loop–helix)–PER–ARNT–SIM (bHLH–PAS) proteins are heterodimeric transcription factors that sense and respond to environmental signals (such as pollutants) or to physiological signals (for example, hypoxia and circadian rhythms) through their two PAS domains. PAS domains form a generic three-dimensional fold, which commonly contains an internal cavity capable of small-molecule binding and outer surfaces adept at protein–protein interactions. These proteins are important in several pro-tumour and antitumour pathways and their activities can be modulated by both natural metabolites and oncometabolites. Recently determined structures and successful small-moleculescreening programmes are now providing new opportunities to discover selective agonists and antagonists directed against this multitasking family of transcription factors.David C. Bersten, Adrienne E. Sullivan, Daniel J. Peet & Murray L. Whitela