A biophysical characterization of the iron coordination environment in wheat germ peroxidase

 The heme protein wheat germ peroxidase (isoenzyme C₂) and its cyanide-inhibited form have been investigated by means of electronic, CD and paramagnetic NMR spectroscopy. The data indicate a protein environment of the active site distinct from that of horseradish peroxidase (HRP), with a larger solvent accessibility. The iron is pentacoordinated at neutral and low pH, whereas a hydroxyl anion may be bound at alkaline pH. The fifth axial ligand is a His residue with a partial anionic character, as found in other peroxidases. A spin equilibrium is observed at high enzyme concentrations. Received: 17 September 1996 / Accepted: 10 January 1997     

Unravelling the coordination between leaf and stem economics spectra through local and global scale approaches

The existence of a coordination between leaf and stem economic spectra in woody species has been postulated repeatedly in the literature, with contrasting results. Here, we postulated that this coordination is conditioned by climate factors, being stronger in stressful environments. To test this hypothesis we explored the coordination between leaf and stem economic spectra in a seasonally dry forest in central Argentina and at the global scale, we analysed if the outcome of their coordination varies along a climatic gradient. At the local scale, we characterized leaf and stem economic spectra in 37 woody species by measuring six leaf and stem functional traits related to resource acquisition and use, and two functional traits used as proxies of water transport and use capacities. At the global scale, a meta‐regression was performed to analyse if the outcome of the coordination among leaf and stem traits varies along gradients of the mean precipitation of the driest quarter and of the minimum temperature of the coldest month. At the local scale, we observed a high integration among the measured leaf and stem traits, and this coordination seemed to be linked to hydraulic properties. At the global scale, we found not only that the overall weighted mean effect size of the correlation between specific leaf area and wood density was significant and negative but also that the coordination between leaf and stem traits seemed to be shaped by climate and tends to become stronger under harsh climate conditions. Furthermore, although our results seem to suggest that their coordination is context‐dependent, alternative strategies could be observed under stressful conditions.     

An illustrated key to the genera and subgenera of the Recent azooxanthellate Scleractinia (Cnidaria,Anthozoa), with an attached glossary

The 120 presently recognized genera and seven subgenera of the azooxanthellate Scleractinia are keyed using gross morphological characters of the corallum. All genera are illustrated with calicular and side views of coralla. All termes used in the key are defined in an illustrated glossary. A table of all species-level keys, both comprehensive and faunistic, is provided covering the last 40 years.     

De Novo Generation of Infectious Prions In Vitro Produces a New Disease Phenotype

Prions are the proteinaceous infectious agents responsible for Transmissible Spongiform Encephalopathies. Compelling evidence supports the hypothesis that prions are composed exclusively of a misfolded version of the prion protein (PrP^Sc) that replicates in the body in the absence of nucleic acids by inducing the misfolding of the cellular prion protein (PrP^C). The most common form of human prion disease is sporadic, which appears to have its origin in a low frequency event of spontaneous misfolding to generate the first PrP^Sc particle that then propagates as in the infectious form of the disease. The main goal of this study was to mimic an early event in the etiology of sporadic disease by attempting de novo generation of infectious PrP^Sc in vitro. For this purpose we analyzed in detail the possibility of spontaneous generation of PrP^Sc by the protein misfolding cyclic amplification (PMCA) procedure. Under standard PMCA conditions, and taking precautions to avoid cross-contamination, de novo generation of PrP^Sc was never observed, supporting the use of the technology for diagnostic applications. However, we report that PMCA can be modified to generate PrP^Sc in the absence of pre-existing PrP^Sc in different animal species at a low and variable rate. De novo generated PrP^Sc was infectious when inoculated into wild type hamsters, producing a new disease phenotype with unique clinical, neuropathological and biochemical features. Our results represent additional evidence in support of the prion hypothesis and provide a simple model to study the mechanism of sporadic prion disease. The findings also suggest that prion diversity is not restricted to those currently known, and that likely new forms of infectious protein foldings may be produced, resulting in novel disease phenotypes.     

High-density genetic mapping for coffee leaf rust resistance

Coffee leaf rust caused by the fungus Hemileia vastatrix causes considerable economic losses for coffee producers. Although agrochemical products can provide sufficient disease control, the use of resistant cultivars is a safer alternative. This resistance may be constrained by one or a few genetic factors, mainly those found in material originating from interspecific hybrids. In this study, the genetic analysis of an F ₂ population consisting of 224 plants derived from a crossing of Híbrido de Timor UFV 427-15 (resistant) with Catuaí Amarelo IAC 30 (susceptible) showed that a dominant gene confers the resistance of coffee to race II of H. vastatrix. From a genetic map saturated with 25 amplified fragment length polymorphism (AFLP) markers linked to the resistance gene, we developed a high-density genetic map with six sequence-characterized amplified region (SCAR) markers delimiting a chromosomal region of 9.45 cM and flanking the dominant gene at 0.7 and 0.9 cM. This is the first saturated and high-density genetic map obtained from this region containing the resistance gene. The results of this study are of great importance for the introduction of molecular markers for marker-assisted selection; they will also facilitate studies related to the cloning, structure, and function of race-specific genes involved in the resistance of coffee trees to H. vastatrix.     

Profiling the changes in signaling pathways in ascorbic acid/β‐glycerophosphate‐induced osteoblastic differentiation

Despite numerous reports on the ability of ascorbic acid and β‐glycerophosphate (AA/β‐GP) to induce osteoblast differentiation, little is known about the molecular mechanisms involved in this phenomenon. In this work, we used a peptide array containing specific consensus sequences (potential substrates) for protein kinases and traditional biochemical techniques to examine the signaling pathways modulated during AA/β‐GP‐induced osteoblast differentiation. The kinomic profile obtained after 7 days of treatment with AA/β‐GP identified 18 kinase substrates with significantly enhanced or reduced phosphorylation. Peptide substrates for Akt, PI3K, PKC, BCR, ABL, PRKG1, PAK1, PAK2, ERK1, ERBB2, and SYK showed a considerable reduction in phosphorylation, whereas enhanced phosphorylation was observed in substrates for CHKB, CHKA, PKA, FAK, ATM, PKA, and VEGFR‐1. These findings confirm the potential usefulness of peptide microarrays for identifying kinases known to be involved in bone development in vivo and in vitro and show that this technique can be used to investigate kinases whose function in osteoblastic differentiation is poorly understood. J. Cell. Biochem. 112: 71–77, 2011. © 2010 Wiley‐Liss, Inc.     

Synchrotron X-ray imaging via ultra-small-angle scattering: principles of quantitative analysis and application in studying bone integration to synthetic grafting materials

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic β-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.     

Lactobacillus salivarius A3iob Reduces the Incidence of Varroa destructor and Nosema Spp. in Commercial Apiaries Located in the Northwest of Argentina

Lactobacillus salivarius A3iob was administered to productive colonies belonging to commercial apiaries of small beekeepers (around 30–50 hives each one), from four departments of the province of Jujuy (Argentina): Yala, Tilquiza, El Carmen, and Los Alisos. The incidence of Varroa destructor and Nosema spp., before and after winter, was monitored during 2 years of study (2014–2015). Depending on the geographical location of each apiary and the application time, a monthly dose of the bacteria (10⁵ CFU/mL) reduced the levels of varroasis between 50 and 80%. Interestingly, L. salivarius A3iob cells remitted the percentage of the mites to undetectable values in an apiary treated with flumethrin (at Yala, Yungas region).

On the other hand, the spore levels of Nosema spp. in the lactobacilli-treated colonies also depended on the apiary and the year of application, but a significant decrease was mainly observed in the post-winter period. However, at Rivera (El Carmen’s department), no significant changes were detected in both parameters.

These results obtained after 2 years of work suggest that delivering L. salivarius A3iob cells to the bee colonies can become a new eco-friendly tool to cooperate with the control of these bees’ pests.

     

Glutathione Reductase-null Malaria Parasites Have Normal Blood Stage Growth but Arrest during Development in the Mosquito

Malaria parasites contain a complete glutathione (GSH) redox system, and several enzymes of this system are considered potential targets for antimalarial drugs. Through generation of a γ-glutamylcysteine synthetase (γ-GCS)-null mutant of the rodent parasite Plasmodium berghei, we previously showed that de novo GSH synthesis is not critical for blood stage multiplication but is essential for oocyst development. In this study, phenotype analyses of mutant parasites lacking expression of glutathione reductase (GR) confirmed that GSH metabolism is critical for the mosquito oocyst stage. Similar to what was found for γ-GCS, GR is not essential for blood stage growth. GR-null parasites showed the same sensitivity to methylene blue and eosin B as wild type parasites, demonstrating that these compounds target molecules other than GR in Plasmodium. Attempts to generate parasites lacking both GR and γ-GCS by simultaneous disruption of gr and γ-gcs were unsuccessful. This demonstrates that the maintenance of total GSH levels required for blood stage survival is dependent on either de novo GSH synthesis or glutathione disulfide (GSSG) reduction by Plasmodium GR. Our studies provide new insights into the role of the GSH system in malaria parasites with implications for the development of drugs targeting GSH metabolism.