Dominant Root Associated Fungi (RAF) from Drynaria quercifolia L. either Induce or Retard Growth of PSB Rc10 Rice (Oryza sativa L.) in Gibberellic Acid-Inhibited Medium

The testing and use of microorganisms for in vitro growth promotion of agriculturally significant crops such as rice has increased but remains underexploited. The current study aims to explore growth-enhancing mechanisms of dominant root-associated fungi (RAF) isolates from Drynaria quercifolia and test their effects on rice. The most abundant RAF on five tree-collection sites were cultured in vitro. Genomic DNA of the RAF were extracted and the ITS (internal transcribed spacer) region of the 18S ribosomal DNA (rDNA) were sequenced and molecularly identified. Two RAF isolates significantly increased the plant shoot/total length (Meyerozyma guilliermondii: 10.29±4.18/13.46±4.18 cm; Trichoderma simmonsii: 10.33±1.38/13.23+1.58 cm), shoot/total fresh weight (Meyerozyma guilliermondii: 57.33±15.76/71.00±16.10 mg; Trichoderma simmonsii: 63.22±12.23/76.00±10.67 mg) and shoot/total dry weight (Meyerozyma guilliermondii: 16.99±6.74/22.78±7.41 mg; Trichoderma simmonsii: 16.89±3.33/23.11±5.30 mg) weight compared to the negative control. These results possibly show the ability of the two isolates to produce the hormone gibberellic acid. On the other hand, three of the RAF isolates did not significantly increase seedling growth and biomass. The Trichoderma yunnanense (shoot: 0.36±0.16 cm; total: 0.53±0.20 cm), unidentified Mucoromycotina isolate F5P1RAF16 (shoot: 1.87±0.59 cm; total: 2.12±0.58 cm) and the unidentified Mucoromycotina isolate F9P2RAF21 (shoot: 3.26±1.56 cm; total: 5.19±2.00 cm) approximated the growth of rice seedlings inoculated with broth and water negative control (shoot: 4.40+2.27 cm; total: 6.38+2.28 cm). This possibly indicates the inability of these isolates to produce GA or their potential ability to produce growth-retarding metabolites. Preliminary data from this study reveal potential growth-promoting capacity of RAF isolates on rice

Amyloid-b peptide on sialyl-LewisX-selectin-mediated membrane tether mechanics at the cerebral endothelial cell surface

Increased deposition of amyloid-b peptide (Ab) at the cerebral endothelial cell (CEC) surface has been implicated in enhancement of transmigration of monocytes across the brain blood barrier (BBB) in Alzheimer’s disease (AD). In this study, quantitative immunofluorescence microscopy (QIM) and atomic force microscopy (AFM) with cantilevers biofunctionalized by sialyl-Lewisx (sLex) were employed to investigate Ab-altered mechanics of membrane tethers formed by bonding between sLex and p-selectin at the CEC surface, the initial mechanical step governing the transmigration of monocytes. QIM results indicated the ability for Ab to increase p-selectin expression at the cell surface and promote actin polymerization in both bEND3 cells (immortalized mouse CECs) and human primary CECs. AFM data also showed the ability for Ab to increase cell stiffness and adhesion probability in bEND3 cells. On the contrary, Ab lowered the overall force of membrane tether formation (Fmtf), and produced a bimodal population of Fmtf, suggesting subcellular mechanical alterations in membrane tethering. The lower Fmtf population was similar to the results obtained from cells treated with an F-actin-disrupting drug, latrunculin A. Indeed, AFM results also showed that both Ab and latrunculin A decreased membrane stiffness, suggesting a lower membrane-cytoskeleton adhesion, a factor resulting in lower Fmtf. In addition, these cerebral endothelial alterations induced by Ab were abrogated by lovastatin, consistent with its anti-inflammatory effects. In sum, these results demonstrated the ability for Ab to enhance p-selectin expression at the CEC surface and induce cytoskeleton reorganization, which in turn, resulted in changes in membrane-cytoskeleton adhesion and membrane tethering, mechanical factors important in transmigration of monocytes through the BBB.This work was supported by Alzheimer Association Grant NIRG-06-24448; NIH Grant 1P01 AG18357, R21NS052385, 5R21AG032579 and in part by 1P01HL095486 and AHA 0835676N; ‘‘Bolashak’’ scholarship and Ministry of Education and Science of the Republic of Kazakhstan 1029/GF2. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Soluble aggregates of the amyloid-β peptide are trapped by serum albumin to enhance amyloid-β activation of endothelial cells

<p>Abstract</p> <p>Background</p> <p>Self-assembly of the amyloid-β peptide (Aβ) has been implicated in the pathogenesis of Alzheimer's disease (AD). As a result, synthetic molecules capable of inhibiting Aβ self-assembly could serve as therapeutic agents and endogenous molecules that modulate Aβ self-assembly may influence disease progression. However, increasing evidence implicating a principal pathogenic role for small soluble Aβ aggregates warns that inhibition at intermediate stages of Aβ self-assembly may prove detrimental. Here, we explore the inhibition of Aβ_1–40self-assembly by serum albumin, the most abundant plasma protein, and the influence of this inhibition on Aβ_1–40activation of endothelial cells for monocyte adhesion.</p> <p>Results</p> <p>It is demonstrated that serum albumin is capable of inhibiting in a dose-dependent manner both the formation of Aβ_1–40aggregates from monomeric peptide and the ongoing growth of Aβ_1–40fibrils. Inhibition of fibrillar Aβ_1–40aggregate growth is observed at substoichiometric concentrations, suggesting that serum albumin recognizes aggregated forms of the peptide to prevent monomer addition. Inhibition of Aβ_1–40monomer aggregation is observed down to stoichiometric ratios with partial inhibition leading to an increase in the population of small soluble aggregates. Such partial inhibition of Aβ_1–40aggregation leads to an increase in the ability of resulting aggregates to activate endothelial cells for adhesion of monocytes. In contrast, Aβ_1–40activation of endothelial cells for monocyte adhesion is reduced when more complete inhibition is observed.</p> <p>Conclusion</p> <p>These results demonstrate that inhibitors of Aβ self-assembly have the potential to trap small soluble aggregates resulting in an elevation rather than a reduction of cellular responses. These findings provide further support that small soluble aggregates possess high levels of physiological activity and underscore the importance of resolving the effect of Aβ aggregation inhibitors on aggregate size.</p

Biosynthesis, isolation and characterization of 57Fe-enriched Phaseolus vulgaris ferritin after heterologous expression in Escherichia coli

10.1007/s00216-007-1691-3Analytical and Bioanalytical Chemistry390153-59ABCN