A function for the calponin family member NP25 in neurite outgrowth

The neuronal protein 25 (NP25), a member of the calponin (CaP) protein family, has previously been identified as neuron-specific protein in the adult rat brain. Here, we show an early onset of NP25 expression in the chick embryo neural tube. NP25 represents, together with NeuroM, one of the earliest markers for postmitotic neurons. To elucidate its function in the developing nervous system, NP25 was overexpressed in E5 and E9 sensory neurons, E7 sympathetic neurons and PC12 cells that show different endogenous NP25 expression levels. Whereas E5 and E9 sensory neurons and PC12 cells, which express low endogenous levels of NP25, responded by enhanced neurite outgrowth, a reduction of neurite length was observed in sympathetic neurons, which already express high endogenous levels of NP25. Knockdown of NP25 in sensory neurons using NP25 siRNA resulted in shorter neurites, whereas reduction of NP25 expression in sympathetic neurons led to increased neurite length. These results suggest a dynamic function for NP25 in the regulation of neurite growth, with an optimal level of NP25 required for maximal growth.     

Mother plant age and seasonal influence on in vitro propagation of <Emphasis Type="Italic">Quercus euboica</Emphasis> Pap., an endemic,rare and endangered oak species of Greece

A micropropagation method for Quercus euboica Pap. was developed. Nodal explants from seedlings gave higher multiplication rates than explants from adult plants. Cultures initiated at the beginning of May produced the highest percentage of shoot forming explants and multiplication rate. Woody Plant Medium (WPM) salts, with 100 mg l⁻¹ myoinositol, 1 mg l⁻¹ thiamine, 0.5 mg l⁻¹ pyridoxine, 0.5 mg l⁻¹ nicotinic acid and 3% sucrose was used as basal medium and several cytokinins at various concentrations were evaluated for their effect on shoot multiplication. The highest shoot multiplication rate was obtained with 4.44 μΜ BA. IBA at 9.84 μΜ in the culture medium during the first week of culture, and if followed by culture in hormone-free medium, gave the best rooting results. Darkness at the beginning of the rooting period did not improve rooting. The use of plastic wrap as a cover material of the culture vessels enhanced rooting percentage and root number. Plantlets acclimatized ex vitro in soil from the natural environment of the species survived at a higher percentage (up to 93%) and had more vigorous growth than plantlets grown in a compost–perlite (2:1 v/v) medium (up to 36%).     

Neurofibromin 1 Is a miRNA Target in Neurons

Mutations of the neurofibromin 1 gene cause neurofibromatosis type 1, a disease in which learning and behavioral abnormalities are common. The disease is completely penetrant but shows variable phenotypic expression in patients. The repertoire of regulatory interactions utilized by neurons to control neurofibromin 1 expression is poorly understood. Here, we examined the contribution of microRNAs into this regulatory network. Using reporter assays, we provided evidence that miR-128 and to a lesser extent miR-137 and miR-103 reduced neurofibromin 1 reporter levels through specific binding to Nf1 3′-UTR. Mutations in all three predicted binding sites eliminated the reporter response. MiR-128 and miR-137, unlike miR-103 that showed a more ubiquitous expression, were predominantly expressed in brain with a distribution that resembled neurofibromin 1 expression in different tissues as well as during the course of neuronal development. In the nervous system, all three microRNAs showed highest expression in neurons and least in Schwann cells and astrocytes. Overexpression of miR-128 alone or with miR-103 and miR-137 significantly reduced endogenous neurofibromin 1 protein levels, while antisense inhibition of these microRNAs enhanced translation of endogenous neurofibromin 1 and reporter in primary cultures of hippocampal neurons. These findings revealed a significant additional mechanism by which neurofibromin 1 is regulated in neurons and implicated new candidates for the treatment of multifarious neurofibromatosis type 1 cognitive symptoms.     

Solvent Effects on Equilibrium Position and Initial Rate of Lipase-catalyzed Esterification Reactions in Organic Solvents: Experimental Results and Prediction Capabilities

The solvent effect on the equilibrium position and the initial rate of esterification of 1-hexanol with acetic acid catalyzed by a lipase has been experimentally investigated. A variety of non-polar and polar solvents have been considered and the results obtained indicate that the solvent effect on the equilibrium conversion is very important compared to that for transesterification reactions. A theoretically sound methodology using the group-contribution UNIFAC model for the prediction of solvent effects on the equilibrium position of enzymatic reactions is presented and it is applied to the reaction of 1-hexanol with acetic acid as well as to a similar reaction from the literature. The results obtained are better than those from empirical methods proposed in the literature such as correlations with the octanol-water partition coefficient of the solvent, as well as the solubility of water in the solvent. Moreover, the proposed methodology can be used for the determination of the equilibrium constant of the reaction. For the prediction of the solvent effect on the initial rate of enzymatic reactions it is found that it is more accurately determined using the product of the activities of the reactants, which can be predicted by the UNIFAC model, than the octanol-water partition coefficient of the solvent or the solubility of water in the solvent.     

Bacillus subtilis QST 713 Confers Protection to Tomato Plants Against Pseudomonas syringae pv tomato and Induces Plant Defence‐related Genes

Bacterial speck, caused by Pseudomonas syringae pv. tomato (Pst), is an economically important disease of tomato, resulting in yield loss of marketable fruit. Management of bacterial speck is a challenge in commercial production fields due to the limited efficacy of current disease management strategies, as the pathogen acquires resistance to antibiotics and fixed copper bactericides and host resistance has not proven durable. Therefore, it is essential to develop alternative disease management strategies, like biological control. In this study, the efficacy of the commercially available biocontrol agent Bacillus subtilis QST 713 along with copper hydroxide was tested against Pst under greenhouse conditions. QST 713 reduced significantly disease severity and incidence compared to control and the copper hydroxide treatment; subsequently, the Pst population was lower in the QST 713‐treated plants compared to control. In parallel, QST 713 and copper hydroxide increased plant height compared to control and mock plants. Furthermore, the quantitative PCR analysis of PR1a, PR1b and Pin2 expression suggests a positive role for Pin2 in the plant protective activity of QST 713, as Pin2 expression was significantly higher in the QST 713‐treated plants challenged with Pst compared to the control Pst‐inoculated plants.     

Depolarisation causes reciprocal changes in GFR(alpha)-1 and GFR(alpha)-2 receptor expression and shifts responsiveness to GDNF and neurturin in developing neurons

GDNF and neurturin are structurally related neurotrophic factors that promote the survival of many different kinds of neurons and influence axonal and dendritic growth and synaptic function. These diverse effects are mediated via multicomponent receptors consisting of the Ret receptor tyrosine kinase plus one of two structurally related GPI-linked receptors, GFR(alpha)-1 and GFR(alpha)-2. To ascertain how the expression of these receptors is regulated during development, we cultured embryonic neurons under different experimental conditions and used competitive RT/PCR to measure the levels of the mRNAs encoding these receptors. We found that depolarising levels of KCl caused a marked increase in GFR(alpha)-1 mRNA and a marked decrease in GFR(&agr;)-2 mRNA in sympathetic, parasympathetic and sensory neurons. These changes were accompanied by increased responsiveness to GDNF and decreased responsiveness to neurturin, and were inhibited by L-type Ca(2+) channel antagonists, suggesting that they were due to elevated intracellular free-Ca(2+). There was no consistent effect of depolarising levels of KCl on ret mRNA expression, and neither GDNF nor neurturin significantly affected receptor expression. These results show that depolarisation has marked and opposing actions on the expression of GFR(&agr;)-1 and GFR(&agr;)-2, which are translated into corresponding changes in neuronal responsiveness to GDNF and neurturin. This provides evidence for a mechanism of regulating the neurotrophic factor responses of neurons by neural activity that has important implications for structural and functional plasticity in the developing nervous system.