Metabolomics Highlights Different Life History Strategies of White and Brown Rot Wood-Degrading Fungi.

White and brown rot fungi efficiently deconstruct lignocellulose in wood, Earth's largest pool of aboveground biotic carbon and an important natural resource. Despite its vital importance, little is known about the metabolomic signatures among fungal species and nutritional modes (rot types). In this study, we used GC-MS metabolomics in solid wood substrates (in planta) to compare brown rot fungi (Rhodonia placenta and Gloeophylum trabeum) and white rot fungi (Trametes versicolor and Pleurotus ostreatus) at two decay stages (earlier and later), finding identifiable patterns for brown rot fungi at later decay stages. These patterns occurred in highly reducing environments that were not observed in white rot fungi. Metabolomes measured among the two white rot fungi were notably different, but we found a potential biomarker compound, galactitol, that was characteristic to white rot taxa. In addition, we found that white rot fungi were more efficient at catabolizing phenolic compounds that were originally present in wood. Collectively, white rot fungi were characterized by measured sugar release relative to higher carbohydrate solubilization by brown rot fungi, a distinction in soluble sugar availability that might shape success in the face of "cheater" competitors. This need to protect excess free sugars may explain the differentially high brown rot fungal production of pyranones and furanones, likely linked to an expansion of polyketide synthase genes. IMPORTANCE Despite the ecological and economic importance of wood-degrading fungi, little is known about the array of metabolites that fungi produce during wood decomposition. This study provides an in-depth insight into the wood decomposition process by analyzing and comparing the changes of >100 compounds produced by fungi with metabolic distinct nutritional modes (white and brown rot fungi) at different decay stages. We found a unique pattern of metabolites that correlated well with brown rot (carbohydrate selective mode) in later decay. These compounds were in line with some of the physiochemical and genetic features previously seen in these fungi such as a faster sugar release, lower pH, and the expansion of polyketide-synthase genes compared to white rot fungi (lignin-degrading mode). This study provides spatiotemporally resolved mechanism insights as well as critical groundwork that will be valuable for studies in basic biology and ecology, as well as applied biomass deconstruction and bioremediation.

Retraction: Pressure-Induced Superconducting State of Europium Metal at Low Temperatures [Phys. Rev. Lett. 102, 197002 (2009)].

Retraction of DOI: 10.1103/PhysRevLett.102.197002.

Pressure-Induced Superconductivity in Elemental Ytterbium Metal.

Ytterbium (Yb) metal is divalent and nonmagnetic (4f^{14} configuration). Under pressure its valence increases significantly leading to the expectation that magnetic instabilities and other highly correlated electron effects may appear before a stable trivalent state is reached (4f^{13} configuration). We carried out electrical resistivity and ac magnetic susceptibility measurements to 179 GPa over the temperature range 1.4-295 K. No evidence for magnetic order is observed. However, Yb becomes a superconductor at 86 GPa with T_{c}≃1.4 K, increasing to 4.6 K at 179 GPa. X-ray absorption spectroscopy shows that Yb remains mixed valent to at least 125 GPa, pointing to an active role of f electrons in the emergence of superconductivity in this simple, elemental solid.

Spontaneous symmetry breaking by charge stripes in the high pressure phase of superconducting La1.875Ba0.125CuO4.

In those cases where charge-stripe order has been observed in cuprates, the crystal structure is such that the average rotational symmetry of the CuO2 planes is reduced from fourfold to twofold. As a result, one could argue that the reduced lattice symmetry is essential to the existence of stripe order. We use pressure to restore the average fourfold symmetry in a single crystal of La1.875Ba0.125CuO4, and show by x-ray diffraction that charge-stripe order still occurs. Thus, electronically driven stripe order can spontaneously break the lattice symmetry.

Enhancement of the critical temperature of HgBa2CuO(4+δ) by applying uniaxial and hydrostatic pressure: implications for a universal trend in cuprate superconductors.

It is well known that the superconducting transition temperature (T(c)) of cuprate superconductors can be enhanced by varying certain structural and electronic parameters, such as the flatness of the CuO2 planes or their doping level. We determine the uniaxial and hydrostatic pressure derivatives of T(c) in the structurally simple tetragonal compound HgBa2CuO(4+δ) near optimal doping. Our results provide experimental evidence for two further methods to enhance T(c): (i) reducing the area of the CuO2 planes, and (ii) increasing the separation of the CuO2 planar groups. T(c) is found to couple much more strongly to the ratio c/a of the lattice constants than to the unit cell volume. A comparison with prior results for structurally more complicated cuprates reveals a general trend of uniaxial pressure derivatives with T(c).

Pressure-induced superconducting state of europium metal at low temperatures.

Divalent Eu (4f;{7}, J=7/2) possesses a strong local magnetic moment which suppresses superconductivity. Under sufficient pressure it is anticipated that Eu will become trivalent (4f;{6}, J=0) and a weak Van Vleck paramagnet, thus opening the door for a possible superconducting state, in analogy with Am metal (5f;{6}, J=0) which superconducts at 0.79 K. We present ac susceptibility and electrical resistivity measurements on Eu metal for temperatures 1.5-297 K to pressures as high as 142 GPa. At approximately 80 GPa Eu becomes superconducting at T_{c} approximately 1.8 K; T_{c} increases linearly with pressure to 2.75 K at 142 GPa. Eu metal thus becomes the 53rd known elemental superconductor in the periodic table.

Pressure-induced superconductivity in CaLi(2).

A search for superconductivity has been carried out on the hexagonal polymorph of Laves-phase CaLi(2), a compound for which Feng, Ashcroft, and Hoffmann predict highly anomalous behavior under pressure. No superconductivity is observed above 1.10 K at ambient pressure. However, high-pressure ac susceptibility and electrical resistivity studies to 81 GPa reveal bulk superconductivity in CaLi(2) at temperatures as high as 13 K. The normal-state resistivity displays a dramatic increase with pressure.

Enhancement of the critical current density of YBa2Cu3Ox superconductors under hydrostatic pressure.

The dependence of the critical current density Jc on hydrostatic pressure to 0.6 GPa is determined for a single 25 degrees [001]-tilt grain boundary in a bicrystalline ring of nearly optimally doped melt-textured YBa2Cu3Ox. Jc is found to increase rapidly under pressure at +20%/GPa. A new diagnostic method is introduced (pressure-induced Jc relaxation) which reveals a sizable concentration of vacant oxygen sites in the grain boundary region. Completely filling such sites with oxygen anions should lead to significant enhancements in Jc.

Postmenopausal hormone replacement: historical perspectives and current concerns.

Despite continuing evidence of its value, hormone replacement (HR) therapy is used by only a minority of postmenopausal women. Some of this reluctance may stem from concerns about the medicalization of menopause and the labeling of menopause as a state of failure or disease that needs to be treated. These concerns are understandable given the impact of previous efforts to apply erroneous biological models to women's physiology, often to their detriment. Some may assert that current attempts to describe menopause as a state of estrogen deficiency are as wrong as previous explanations that the backing up of menstrual blood required purging and bleeding. However, there is an abundance of research attesting to the value of HR in decreasing such menopausal symptoms as hot flashes and insomnia and in preventing chronic problems, including urogenital atrophy and osteoporosis. In addition, recent research suggests that estrogen may have positive effects on cognition. Questions about HR and breast cancer remain, and several studies have found a small increase in breast cancer among long-term estrogen users. The recent introduction of selective estrogen response modifiers may further increase the safety of HR therapy. Many women worried about breast cancer and other possible estrogenic effects of HR are seeking approaches they consider more natural to managing menopause, turning to such untested remedies as soy supplements and herbs. While awaiting rigorous trials, clinicians can help patients understand the consequences of relying on therapies that have unknown long-term safety and effectiveness.

Hyperthyroidism: diagnosis and management of Graves' disease.

Hyperthyroidism, or thyrotoxicosis, results when the body's tissues are exposed to excessive levels of thyroid hormone. Hyperthyroidism affects 2% of women but only one-tenth as many men. Graves' disease is the most common form of hyperthyroidism, often occurring in young adults. It is an autoimmune disorder with an important genetic component. Hyperthyroidism's hallmarks include goiter and myriad signs and symptoms related to increased metabolic activity in virtually all body tissues. Increased sensitivity to circulating catecholamines adds to the clinical picture. Diagnosed by patient history, physical examination, and laboratory tests, Graves' disease is treated with antithyroid drugs, radioactive iodine, and/or surgery, plus supportive therapy. A good treatment outcome can be expected; long-term follow-up is indicated.

New hydrostatic pressure cell to 90 kilobars for precise electrical and magnetic measurements at low temperatures.

A new type of hydrostatic pressure cell is discussed. It is suitable for precise electrical and magnetic measurements on several samples simultaneously over a wide range of temperature and pressure. Pressures as high as 90 kilobars have thus far been reached in a four-point electrical resistivity measurement. These studies indicate minimal pressure changes upon cooling from 300 to 1 K, good pressure homogeneity, and absence of significant shear stresses.