Changes in microbial biomass,community composition and diversity,and functioning with soil depth in two alpine ecosystems on the Tibetan plateau

Plant and Soil - Plant P acquisition strategies are driven by multiple belowground morphological and physiological traits as well as interactions among these traits. This study aimed to...     

Dimerization and phosphorylation of thyrotropin-releasing hormone receptors are modulated by agonist stimulation

Dimerization and phosphorylation of thyrotropin-releasing hormone (TRH) receptors was characterized using HEK293 and pituitary GHFT cells expressing epitope-tagged receptors. TRH receptors tagged with FLAG and hemagglutinin epitopes were co-precipitated only if they were co-expressed, and 10-30% of receptors were isolated as hemagglutinin/FLAG-receptor dimers under basal conditions. The abundance of receptor dimers was increased when cells had been stimulated by TRH, indicating that TRH either stabilizes pre-existing dimers or increases dimer formation. TRH increased receptor dimerization and phosphorylation within 1 min in a dose-dependent manner. TRH increased phosphorylation of both receptor monomers and dimers, documented by incorporation of (32)P and an upshift in receptor mobility reversed by phosphatase treatment. The ability of TRH to increase receptor phosphorylation and dimerization did not depend on signal transduction, because it was not inhibited by the phospholipase C inhibitor. Receptor phosphorylation required an agonist but was not blocked by the casein kinase II inhibitor apigenin, the protein kinase C inhibitor GF109203X, or expression of a dominant negative form of G protein-coupled receptor kinase 2. TRH receptors lacking most of the cytoplasmic carboxyl terminus formed dimers constitutively but failed to undergo agonist-induced dimerization and phosphorylation. TRH also increased phosphorylation and dimerization of TRH receptors expressed in GHFT pre-lactotroph cells.     

Coordinating cell proliferation and differentiation

Cell proliferation and differentiation are highly coordinated processes during development. Recent studies have revealed that this coordination may result from dual functions residing in the central regulators of proliferation, allowing them to also regulate differentiation. Studies have also shown that some terminally differentiated cells can be made to divide beyond their normal capacity.     

Kv1 potassium channel C-terminus constant HRETE region: arginine substitution affects surface protein level and conductance level of subfamily members differentially

We have shown previously that truncating all of the variable cytoplasmic C-terminus of Kv1.1 potassium channels to G421stop had only a small inhibitory effect on their cell surface conductance density levels and cell surface protein levels. Here we investigated the role of a highly conserved cytoplasmic C-terminal charged region of five amino acids (HRETE) of the S6 transmembrane domain in the protein and conductance expression of Kv1.1, Kv1.2, and Kv1.4 channels. For Kv1.1 we found that E420stop, T419stop, and E418stop showed cell surface conductance densities and cell surface protein levels similar to full length control, whereas R417stop and H416stop exhibited essentially no conductance but their surface protein levels were similar to full length control. A bulky non-negatively charged hydrophilic amino acid at position 417 appeared to be critical for wild type gating of Kv1.1 because R417K and R417Q rescued conductance levels whereas R417A or R417E did not. The R417A mutation in the full length Kv1.1 also exhibited surface protein levels similar to control but it did not exhibit significant conductance. In contrast, mutation of the equivalent arginine to alanine in full length Kv1.2 and Kv1.4 appeared to have little or no effect on channel conductance but rather decreased cell surface protein levels by inducing partial high ER retention. These findings are consistent with the notion that the arginine amino acid in the HRETE region plays a different role in affecting conductance levels or cell surface protein levels of very closely related Kv1 potassium channels.     

Pulmonary type II cell hypertrophy and pulmonary lipoproteinosis are features of chronic IL-13 exposure

Interleukin (IL)-13, a key mediator of Th2-mediated immunity, contributes to the pathogenesis of asthma and other pulmonary diseases via its ability to generate fibrosis, mucus metaplasia, eosinophilic inflammation, and airway hyperresponsiveness. In these studies, we compared surfactant accumulation in wild-type mice and mice in which IL-13 was overexpressed in the lung. When compared with littermate controls, transgenic animals showed alveolar type II cell hypertrophy under light and electron microscopy. Over time, their alveoli also filled with surfactant in a pulmonary alveolar proteinosis pattern. At the same time, prominent interstitial fibrosis occurs. Bronchoalveolar lavage fluid from these mice had a three- to sixfold increase in surfactant phospholipids. Surfactant proteins (SP)-A, -B, and -C showed two- to threefold increases, whereas SP-D increased 70-fold. These results indicate that IL-13 is a potent stimulator of surfactant phospholipid and surfactant accumulation in the lung. IL-13 may therefore play a central role in the broad range of chronic pulmonary conditions in which fibrosis, type II cell hypertrophy, and surfactant accumulation occur.     

Construction of a high density integrated genetic map for cucumber (Cucumis sativus L.)

The high-density consensus map was constructed based on the GY14 × PI 183967 map from an inter-subspecific cross and the extended S94 × S06 map from an intra-subspecific cross. The consensus map was composed of 1,369 loci, including 1,152 SSR loci, 192 SRAP loci, 21 SCAR loci and one STS locus as well as three gene loci of fruit external quality traits in seven chromosomes, and spanned 700.5 cM, of which 682.7 cM (97.5%) were covered by SSR markers. The average genetic distance and physical interval between loci were 0.51 cM and ~268 kbp, respectively. Additionally, the physical position of the sequence-associated markers aligned along the assembled cucumber genome sequence established a relationship between genetic maps and cucumber genome sequence and to a great extent validated the order of markers in individual maps and consensus map. This consensus map with a high marker density and well-ordered markers is a saturated and reliable linkage map for genetic analysis of cucumber or the Cucurbitaceae family of plants.     

Local habitat condition rather than geographic distance determines the genetic structure of Tamarix chinensis populations in Yellow River Delta,China

Tree Genetics &; Genomes - To breed a new variety of coffee (Coffea arabica) requires approximately 25&;nbsp;years due to the long generation time (5–6&;nbsp;years) of this perennial...