Silicon cycled by tropical forest trees: effects of species,elevation and parent material on Mount Kinabalu,Malaysia

Plant and Soil - We aimed to compare uptake and litter flux of silicon (Si) across tropical tree species and sites on Mt. Kinabalu, Borneo. Si flux components were measured at eight plots in...     

Creatine kinase isoenzyme activity during and after an ultra-distance (200 km) run

It is commonly assumed that creatine kinase (CK) activity in plasma is related to the state of an inflammatory response at 24-48 h, and also it has shown biphasic patterns after a marathon run. No information is available on CK isoenzymes after an ultra-marathon run. The purpose of the present study is to examine the CK isoenzymes after a 200 km ultra-marathon run and during the subsequent recovery. Blood samples were obtained during registration 1 2 h before the 200-km race and during the race at 100 km, 150 km and at the end of 200 km, as well as after a 24 h period of recovery. Thirty-two male ultra-distance runners participated in the study. Serum CPK showed a marked increase throughout the race and 24 h recovery period (p < 0.001). Serum CK during the race occurs mostly in the CK-MM isoform and only minutely in the CK-MB isoform and is unchanged in the CK-BB isoform. High-sensitivity C-reactive protein (hs-CRP), oestradiol, AST and ALT increased significantly from the pre-race value at 100 km and a further increase took place by the end of the 200 km run. The results of our study demonstrate a different release pattern of creatine kinase after an ultra-distance (200 km) run compared to the studies of marathon running and intense eccentric exercise, and changes in several biomarkers, indicative of muscle damage during the race, were much more pronounced during the latter half (100–200 km) of the race. However, the increases in plasma concentration of muscle enzymes may reflect not only structural damage, but also their rate of clearance.     

Novel subdomains of the mouse olfactory bulb defined by molecular heterogeneity in the nascent external plexiform and glomerular layers

Background  

In the mouse olfactory system, the role of the olfactory bulb in guiding olfactory sensory neuron (OSN) axons to their targets is poorly understood. What cell types within the bulb are necessary for targeting is unknown. What genes are important for this process is also unknown. Although projection neurons are not required, other cell-types within the external plexiform and glomerular layers also form synapses with OSNs. We hypothesized that these cells are important for targeting, and express spatially differentially expressed guidance cues that act to guide OSN axons within the bulb.     

Involvement of calcium ion in the stimulated shoot elongation of arrowhead tubers under anaerobic conditions

Shoot elongation of arrowhead (Sagittaria pygmaea Miq.) tubers was stimulated in anaerobic conditions. The anaerobic elongation was attributed to stimulation of cell elongation in the middle of the shoots. The anaerobic elongation of the shoots was severely inhibited by ethylene glycol bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA). The EGTA inhibition was completely nullified by exogenous CaCl2, which acts as an enhancer of anaerobic elongation. Moreover, calcium channel blockers, verapamil, diltiazem and LaCl3, inhibited the anaerobic elongation enhanced by CaCl2. These results showed that calcium plays an important role in stimulating the elongation in anaerobic conditions. Incorporation of 45Ca into the shoot tissues was measured to determine the involvement of calcium uptake in anaerobic elongation. Incorporation of 45Ca into the cell sap, which was collected from frozen and thawed shoots after thorough washing with LaCl3, was significantly stimulated in anaerobic conditions. Verapamil and diltiazem prevented the stimulation of 45Ca incorporation in anaerobic conditions. These results suggest that calcium uptake from the medium serves to enhance shoot elongation of arrowhead tubers under anaerobic conditions.     

Isolation of two populations of sperm cells and microelectrophoresis of pairs of sperm cells from pollen tubes of tobacco (Nicotiana tabacum)

Prior research has indicated that the two sperm cells of Nicotiana tabacum are dimorphic, suggesting that they may participate in preferential fertilization during in vivo fusion with the egg and central cells. To probe the mechanism of potential preferential fertilization in this plant, it will be necessary to use modern sensitive molecular techniques. For this purpose, two individual populations of two sperm cells, constituting the Svn (associated with the vegetative nucleus) and Sua (unassociated with the vegetative nucleus), were isolated in the thousands from tobacco pollen tubes with a micromanipulator as a preliminary step toward research on gametic recognition using molecular techniques. Microelectrophoresis of paired sperm cells from a single pollen tube was conducted at different developmental stages. Sperm cells isolated from 1-, 2-, 3- and 4-cm stylar lengths migrated to the negative pole, with the Sua displaying significantly greater electrophoretic mobility than the Svn, reflecting a more positively charged cell surface on the Sua. The sperm cells isolated from 1-cm style are very sensitive to electron potential in an electrophoretic field, presumably reflecting that they are still in a young state. Differences in cell surface charge between the Sua and Svn may be related with cell fate during fertilization. Supported by National Natural Science Foundation of CHINA (30170060)     

Involvement of plasma membrane H+-ATPase in anoxic elongation of stems in pondweed (Potamogeton distinctus) turions

? Pondweed (Potamogeton distinctus) turions can elongate in the absence of O(2). Alcoholic fermentation serves to produce energy for anoxic elongation via the breakdown of starch stored in cells. However, the mechanism of cell growth during anoxic elongation is not fully understood. ? Changes in pH, H(+) equivalent and lactate content of the incubation medium were measured during anoxic elongation. The effects of fusicoccin (FC), indole-3-acetic acid (IAA), vanadate, erythrosine B and K(+) channel blockers on anoxic elongation were examined. Cytoplasmic pH and vacuolar pH were measured by (31)P nuclear magnetic resonance (NMR) spectroscopy. ? Acidification of the incubation medium occurred during anoxic elongation. The contribution of CO(2) and lactic acid was not sufficient to explain the acidification. FC and IAA enhanced the elongation of stem segments. Vanadate and erythrosine B inhibited anoxic elongation. Acid growth of notched segments was observed. The activity of plasma membrane H(+)-ATPase extracted from pondweed turions was increased slightly in anoxic conditions, but that from pea epicotyls sensitive to anoxic conditions was decreased by incubation in anoxic conditions. Both the cytoplasmic pH and vacuolar pH of pondweed turion cells chased by (32)P NMR spectroscopy were stabilized during a short period < 3 h after anoxic conditions. ? We propose that the enhancement of H(+) extrusion by anoxic conditions induces acidification in the apoplast and may contribute to the stabilization of pH in the cytoplasm.     

Deletion of Hypoxia-Inducible Factor-1α in Adipocytes Enhances Glucagon-Like Peptide-1 Secretion and Reduces Adipose Tissue Inflammation

It is known that obese adipose tissues are hypoxic and express hypoxia-inducible factor (HIF)-1α. Although some studies have shown that the expression of HIF-1α in adipocytes induces glucose intolerance, the mechanisms are still not clear. In this study, we examined its effects on the development of type 2 diabetes by using adipocyte-specific HIF-1α knockout (ahKO) mice. ahKO mice showed improved glucose tolerance compared with wild type (WT) mice. Macrophage infiltration and mRNA levels of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor α (TNFα) were decreased in the epididymal adipose tissues of high fat diet induced obese ahKO mice. The results indicated that the obesity-induced adipose tissue inflammation was suppressed in ahKO mice. In addition, in the ahKO mice, serum insulin levels were increased under the free-feeding but not the fasting condition, indicating that postprandial insulin secretion was enhanced. Serum glucagon-like peptide-1 (GLP-1) levels were also increased in the ahKO mice. Interestingly, adiponectin, whose serum levels were increased in the obese ahKO mice compared with the obese WT mice, stimulated GLP-1 secretion from cultured intestinal L cells. Therefore, insulin secretion may have been enhanced through the adiponectin-GLP-1 pathway in the ahKO mice. Our results suggest that the deletion of HIF-1α in adipocytes improves glucose tolerance by enhancing insulin secretion through the GLP-1 pathway and by reducing macrophage infiltration and inflammation in adipose tissue.     

A set of external reference controls/probes that enable quality assurance between different microarray platforms

RNA external standards, although important to ensure equivalence across many microarray platforms, have yet to be fully implemented in the research community. In this article, a set of unique RNA external standards (or RNA standards) and probe pairs that were added to total RNA in the samples before amplification and labeling are described. Concentration–response curves of RNA external standards were used across multiple commercial DNA microarray platforms and/or quantitative real-time polymerase chain reaction (RT–PCR) and next-generation sequencing to identify problematic assays and potential sources of variation in the analytical process. A variety of standards can be added in a range of concentrations spanning high and low abundances, thereby enabling the evaluation of assay performance across the expected range of concentrations found in a clinical sample. Using this approach, we show that we are able to confirm the dynamic range and the limit of detection for each DNA microarray platform, RT–PCR protocol, and next-generation sequencer. In addition, the combination of a series of standards and their probes was investigated on each platform, demonstrating that multiplatform calibration and validation is possible.