Clonal variation for shoot ontogenetic heteroblasty in maritime pine (Pinus pinaster Ait.)

Pine seedling shoots undergo sharp heteroblastic changes during the early ontogenetic stages. The rate of these changes has been seen to vary between species and provenances within species, but there is a marked lack of information about its genetic control at the lower hierarchical levels. We used clonal replicates of maritime pine to determine broad-sense heritability of shoot ontogenetic heteroblasty and its correlation to rooting ability. We applied a simple ontogenetic index based on the proportion of basal nodes with secondary needles in rooted cuttings of 15 clones from 9 environmentally contrasting origins. We found a high clonal heritability for shoot ontogenetic index and a moderately high heritability for rooting ability, but both genetic and phenotypic correlations between these two traits were weak and non-significant. These results indicate that both developmental phenomena are genetically controlled, but not strictly associated in this species.     

Assessment of dopamine D₁ receptor affinity and efficacy of three tetracyclic conformationally-restricted analogs of SKF38393

To assess the effect of conformational mobility on receptor activity, the β-phenyl substituent of dopamine D(1) agonist ligands of the phenylbenzazepine class, (±)-6,6a,7,8,9,13b-hexahydro-5H-benzo[d]naphtho[2,1-b]azepine-11,12-diol (8), and its oxygen and sulfur bioisosteres 9 and 10, respectively, were synthesized as conformationally-restricted analogs of SKF38393, a dopamine D(1)-selective partial agonist. Compounds trans-8b, 9, and 10 showed binding affinity comparable to that of SKF38393, but functionally, they displayed only very weak agonist activity. These results suggest that the conformationally-restricted structure of the analogs cannot adopt a binding orientation that is necessary for agonist activity.     

Ferritins, bacterial virulence and plant defence

The enterobacterial pathogen Erwinia chrysanthemi causes soft rot diseases on a wide range of plants, including the model plant Arabidopsis thaliana. This bacterium proliferates in the host by secreting a set of pectin degrading enzymes responsible for symptom development. In addition, survival of this bacterium in planta requires two high-affinity iron acquisition systems mediated by siderophores and protective systems against oxidative damages, suggesting the implication by both partners of accurate mechanisms controlling their iron homeostasis under conditions of infection. In this review, we address this question and we show that ferritins both from the pathogen and the host are subtly implicated in the control of this interplay.     

Negative regulation of cadmium tolerance in Arabidopsis by MMDH2

Plant Molecular Biology - MMDH2 gene negatively regulates Cd tolerance by modulating reactive oxygen species (ROS) levels and the ROS-mediated signaling, thus, affecting the expression of PDR8. The...     

Whole cell nuclear magnetic resonance characterization of two photochemically active states of the photosynthetic reaction center in heliobacteria

Applying photo-CIDNP (photochemically induced dynamic nuclear polarization) MAS (magic-angle spinning) nuclear magnetic resonance to whole cells of Heliobacillus (Hb.) mobilis, we demonstrate that heliobacterial reaction centers are operational in two different states as indicated by the occurrence of a light-induced spin-correlated radical pair. A culture maintained anaerobically is called "Braunstoff" (German for "brown substance"). After exposure to oxygen, Braunstoff is converted to "Grünstoff" ("green substance") as indicated by a color change due to the conversion of BChl g to Chl a(F). It is shown that electron transfer occurs symmetrically via both branches of cofactors in both forms. The donor and acceptor cofactors remain identical and unchanged upon conversion, while the intermediate accessory cofactors are transformed from BChl g to Chl a(F). The donor triplet state in Braunstoff is localized on the special pair donor and lives for 100 μs, demonstrating the absence of nearby carotenoids. In Grünstoff, the donor triplet becomes mobile and appears to be formed on an accessory cofactor.     

Comprehensive determination of protein tyrosine pKa values for photoactive yellow protein using indirect 13C NMR spectroscopy

Upon blue-light irradiation, the bacterium Halorhodospira halophila is able to modulate the activity of its flagellar motor and thereby evade potentially harmful UV radiation. The 14 kDa soluble cytosolic photoactive yellow protein (PYP) is believed to be the primary mediator of this photophobic response, and yields a UV/Vis absorption spectrum that closely matches the bacterium's motility spectrum. In the electronic ground state, the para-coumaric acid (pCA) chromophore of PYP is negatively charged and forms two short hydrogen bonds to the side chains of Glu-46 and Tyr-42. The resulting acid triad is central to the marked pH dependence of the optical-absorption relaxation kinetics of PYP. Here, we describe an NMR approach to sequence-specifically follow all tyrosine side-chain protonation states in PYP from pH 3.41 to 11.24. The indirect observation of the nonprotonated ¹³C_γ resonances in sensitive and well-resolved two-dimensional ¹³C-¹H spectra proved to be pivotal in this effort, as observation of other ring-system resonances was hampered by spectral congestion and line-broadening due to ring flips. We observe three classes of tyrosine residues in PYP that exhibit very different pK_a values depending on whether the phenolic side chain is solvent-exposed, buried, or hydrogen-bonded. In particular, our data show that Tyr-42 remains fully protonated in the pH range of 3.41–11.24, and that pH-induced changes observed in the photocycle kinetics of PYP cannot be caused by changes in the charge state of Tyr-42. It is therefore very unlikely that the pCA chromophore undergoes changes in its electrostatic interactions in the electronic ground state.     

Seasonal abundance, number of annual generations, and effect of an entomopathogenic fungus on Phlebotomus papatasi (Diptera: Psychodidae)

The monthly density of the sand fly, Phlebotomus Papatasi Scopoli (Diptera: Psychodidae), was monitored during 2009 at Burg El-Arab, a rural district located close to the Mediterranean coast of Egypt. The number of annual generations and the efficacy of microbial control by the entomopathogenic fungus, Metrahizium anisopliae (Metsch.) Sorok (Ma79), were determined in the laboratory under atmospheric conditions, simulating those of the animal shelters in the study area. We used two collecting techniques; CDC light traps and oiled paper traps, to quantify sand fly density inside houses and in the open field. Adult flies exhibited a seasonal range from April to December. The seasonal pattern was bimodal, with one peak in July and the second one in October. Calculations of the correlation coefficient (r) revealed a significant role of temperature and relative humidity in the monthly abundance of the sand flies in the study area. P. papatasi colony completed seven annual generations under semifield conditions, but the mean developmental time of each immature stage and the mean total duration of development from egg to adult for each generation varied according to the prevailing temperature. The longest generation time was observed in winter (the mean ± SD was 118 ± 11.70 d), and the shortest one occurred at the highest temperatures in summer (the mean ± SD was 25.21 ± 2.04 d). In microbial control studies, the entomopathogenic fungus, M. anisopliae, was used at 15 × 10(8) spores/g food as a standard dose against the second-instar larvae of P. papatasi at the different seasons during 2009. Mortality reached 100% in winter and decreased to 56.0% as the prevailing temperature increased during the summer season.     

Variation of phenolic composition and biological activities in Limoniastrum monopetalum L. organs

Changes in phenolic composition and biological activities were investigated in different Limoniastrum monopetalum L. organs. For that, 80% aqueous acetone extracts were used to estimate total phenolic contents and their antioxidant activities were evaluated using DPPH· and O₂^·− radical scavenging activities and reducing power. The efficiency of organ extracts was tested against human pathogen strains. Ultimately, acid hydrolysis of all organs was subjected to RP-HPLC for phenolic identification. Results showed that flower extracts exhibited the highest polyphenol (65.42 GAE/g DW) and flavonoid (35.36 CE/g DW) contents. Stems were enriched in condensed tannin content (21.4 mg CE/g DW) and displayed the best antiradical activities and the highest reducing power. Besides, stem and gall extracts showed the highest efficiency against pathogenic bacteria as compared with those of flower. Concerning the antifungal test, a slight activity was found in gall extracts. The RP-HPLC showed a difference in phenolic compounds that varied as function of organ. In fact, the major phenolic compound varied as function of organ. Results suggest that L. monopetalum could be a promising source of biomolecules for therapeutic and nutraceutical industries and the difference between organs may be related to their physiological role.     

Olfactory epithelia differentially express neuronal markers

All three olfactory epithelia, the olfactory epithelium proper (OE), the septal organ of Masera (SO), and the vomeronasal organ of Jacobson (VNO) originate from the olfactory placode. Here, their diverse neurochemical phenotypes were analyzed using the immunohistochemical expression pattern of different neuronal markers. The olfactory bulb (OB) served as neuronal control. Neuronal Nuclei Marker (NeuN) is neither expressed in sensory neurons in any of the three olfactory epithelia, nor in relay neurons (mitral/tufted cells) of the OB. However, OB interneurons (periglomerular/granule cells) labeled, as did supranuclear structures of VNO supporting cells and VNO glands. Protein Gene Product 9.5 (PGP9.5 = C-terminal ubiquitin hydrolase L1 = UCHL1) expression is exactly the opposite: all olfactory sensory neurons express PGP9.5 as do OB mitral/tufted cells but not interneurons. Neuron Specific Enolase (NSE) expression is highest in the most apically located OE and SO sensory neurons and patchy in VNO. In contrast, the cytoplasm of the most basally located neurons of OE and SO immunoreacted for Growth Associated Protein 43 (GAP-43/B50). In VNO neurons GAP-43 labeling is also nuclear. In the cytoplasm, Olfactory Marker Protein (OMP) is most intensely expressed in SO, followed by OE and least in VNO neurons; further, OMP is also expressed in the nucleus of basally located VNO neurons. OB mitral/tufted cells express OMP at low levels. Neurons closer to respiratory epithelium often expressed a higher level of neuronal markers, suggesting a role of those markers for neuronal protection against take-over. Within the VNO the neurons show clear apical–basal expression diversity, as they do for factors of the signal transduction cascade. Overall, expression patterns of the investigated neuronal markers suggest that OE and SO are more similar to each other than to VNO.