South American leaf blight intensity evaluated in six clones of young and adult rubber trees in the Vale do Ribeira region, Sao Paulo state, Brazil

Rubber tree clones present different intensity of symptoms, depending on their age. This is mostly clearly seen in the presence or absence of old leaves with ascopores, corresponding to flows of new and susceptible leaves. The objective of this work was to evaluate the intensity of symptoms of south American leaf blight (SALB) in six rubber tree clones, one and eight years old, in the Vale do Ribeira region, Sao Paulo state. The results Showed that clones FX 3864, RRIM 600, IAN 873 and IAN 717 Suffered more attacks when young, and RRIM 600, IAN 717 and FX 3864 when adult. The clone IAN 873 showed the smallest amounts of disease in the adult phase, due to uniform change in the leaves and a compact flow of new leaves, which happened during a season that was unfavorable to pathogen infection, presenting the phenomenon of avoidance or evasion in time.

Culture-Independent Assessment of Rhizobiales-Related Alphaproteobacteria and the Diversity of Methylobacterium in the Rhizosphere and Rhizoplane of Transgenic Eucalyptus

The rhizosphere is an ecosystem exploited by a variety of organisms involved in plant health and environmental sustainability. Abiotic factors influence microorganism-plant interactions, but the microbial community is also affected by expression of heterologous genes from host plants. In the present work, we assessed the community shifts of Alphaproteobacteria phylogenetically related to the Rhizobiales order (Rhizobiales-like community) in rhizoplane and rhizosphere soils of wild-type and transgenic eucalyptus. A greenhouse experiment was performed and the bacterial communities associated with two wild-type (WT17 and WT18) and four transgenic (TR-9, TR-15, TR-22, and TR-23) eucalyptus plant lines were evaluated. The culture-independent approach consisted of the quantification, by real-time polymerase chain reaction (PCR), of a targeted subset of Alphaproteobacteria and the assessment of its diversity using PCR-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone libraries. Real-time quantification revealed a lesser density of the targeted community in TR-9 and TR-15 plants and diversity analysis by principal components analysis, based on PCR-DGGE, revealed differences between bacterial communities, not only between transgenic and nontransgenic plants, but also among wild-type plants. The comparison between clone libraries obtained from the transgenic plant TR-15 and wild-type WT17 revealed distinct bacterial communities associated with these plants. In addition, a culturable approach was used to quantify the Methylobacterium spp. in the samples where the identification of isolates, based on 16S rRNA gene sequences, showed similarities to the species Methylobacterium nodulans, Methylobacterium isbiliense, Methylobacterium variable, Methylobacterium fujisawaense, and Methylobacterium radiotolerans. Colonies classified into this genus were not isolated from the rhizosphere but brought in culture from rhizoplane samples, except for one line of the transgenic plants (TR-15). In general, the data suggested that, in most cases, shifts in bacterial communities due to cultivation of transgenic plants are similar to those observed when different wild-type cultivars are compared, although shifts directly correlated to transgenic plant cultivation may be found.

Phenolic composition of South American red wines classified according to their antioxidant activity, retail price and sensory quality

In this study, 73 South American red wines (Vitis vinifera) from 5 varietals were classified based on sensory quality, retail price and antioxidant activity and characterised in relation to their phenolic composition. ORAC and DPPH assays were assessed to determine the antioxidant activity, and sensory analysis was conducted by seven professional tasters using the Wine Spirits Education Trust`s structured scales. The use of multivariate statistical techniques allowed the identification of wines with the best combination of sensory characteristics, price and antioxidant activity. The most favourable varieties were Malbec, Cabernet Sauvignon, and Syrah produced in Chile and Argentina. Conversely, Pinot Noir wines displayed the lowest sensory characteristics and antioxidant activity. These results suggest that the volatile compounds may be the main substances responsible for differentiating red wines on the basis of sensory evaluation. (C) 2011 Elsevier Ltd. All rights reserved.

Microcystins in South American aquatic ecosystems: Occurrence, toxicity and toxicological assays

The acute poisoning of chronic renal patients during hemodialysis sessions in 1996 in Caruaru City (Pernambuco State, Brazil) stimulated an intensive search for the cause of this severe complication. This search culminated in the identification of microcystins (MC), hepatotoxic cyclic heptapeptides produced by cyanobacteria, as the causative agents. More than ten years later, additional research data provides us with a better understanding of the factors related to cyanobacterial bloom occurrence and production of MC in Brazil and other South American countries. The contamination of water bodies and formation of toxic blooms remains a very serious concern, especially in countries in which surface water is used as the main source for human consumption. The purpose of this review is to highlight the discoveries of the past 15 years that have brought South American researchers to their current level of understanding of toxic cyanobacteria species and that have contributed to their knowledge of factors related to MC production, mechanisms of action and consequences for human health and the environment. (C) 2010 Elsevier Ltd. All rights reserved.

Relaxation evoked by extracellular Ca(2+) in rat aorta is nerve-independent and involves sarcoplasmic reticulum and L-type Ca(2+) channell

The perivascular nerve network expresses a Ca(2+) receptor that is activated by high extracellular Ca(2+) concentrations and causes vasorelaxation in resistance arteries. We have verified the influence of perivascular nerve fibers on the Ca(2+)-induced relaxation in aortic rings. To test our hypothesis, either pre-contracted aortas isolated from rats after sensory denervation with capsaicin or aortic rings acutely denervated with phenol were stimulated to relax with increasing extracellular Ca(2+) concentration. We also studied the role of the endothelium on the Ca(2+)-induced relaxation, and we verified the participation of endothelial/nonendothelial nitric oxide and cyclooxygenise-arachidonic acid metabolites. Additionally, the role of the sarcoplasmic reticulum, K(+) channels and L-type Ca(2+) channels on the Ca(2+)-induced relaxation were evaluated. We have observed that the Ca(2+)-induced relaxation is completely nerve independent, and it is potentiated by endothelial nitric oxide (NO). In endothelium-denuded aortic rings, indomethacin and AH6809 (PGF(2 alpha) receptor antagonist) enhance the relaxing response to Ca(2+). This relaxation is inhibited by thapsigargin and verapamil, while was not altered by tetraethylammonium. In conclusion, we have shown that perivascular nervous fibers do not participate in the Ca(2+)-induced relaxation, which is potentiated by endothelial NO. In endothelium-denuded preparations, indomethacin and AH6809 enhance the relaxation induced by Ca(2+). The relaxing response to Call was impaired by verapamil and thapsigargin, revealing the importance of L-type Ca(2+) channels and sarcoplasmic reticulum in this response. (c) 2008 Elsevier Inc. All rights reserved.

ATP-induced apoptosis involves a Ca(2+)-independent phospholipase A(2) and 5-lipoxygenase in macrophages

Macrophages express P2X(7) and other nucleotide (P2) receptors, and display the phenomena of extracellular ATP (ATP(e))-induced P2X(7)-dependent membrane permeabilization and cell death by apoptosis and necrosis. P2X7 receptors also cooperate with toll-like receptors (TLRs) to induce inflammasome activation and IL-1 beta secretion. We investigated signaling pathways involved in the induction of cell death by ATP, in intraperitoneal murine macrophages. Apoptosis (hypodiploid nuclei) and necrosis (LDH release) were detected 6 h after an induction period of 20 min in the presence of ATP Apoptosis was blocked by caspase 3 and caspase 9 inhibitors and by cyclosporin A. The MAPK inhibitors PD-98059, SB-203580 and SB-202190 provoked no significant effect oil apoptosis, but SB-203580 blocked LDH release. Neither apoptosis nor necrosis was inhibited when both intra- and extracellular Ca(2+) were chelated during the induction period. Mepacrine, a generic PLA(2) inhibitor and BEL, an inhibitor of Ca(2+)-independent PLA(2) (iPLA(2)) blocked apoptosis, while pBPB and AACOOPF(3). inhibitors of secretory and Ca(2+)-dependent PLA(2) respectively, had no significant effect. Cycloxygenase inhibitors had no effect on apoptosis, while the inhibitors of lipoxygenase (LOX) and leukotriene biosynthesis nordihydroguaiaretic acid (NDGA), zileuton, AA-861, and MK-886 significantly decreased apoptosis. Neither NDGA nor MK-886 blocked apoptosis of 5-LOX(-/-) macrophages. CP-105696 and MK-571, antagonists of leukotriene receptors, had no significant effect on apoptosis. None of the inhibitors of PLA(2) and LOX/leukotriene pathway had a significant inhibitory effect on LDH release. Our results indicate that a Ca(2+) -independent step involving an iPLA(2) and 5-LOX are involved in the triggering of apoptosis but not necrosis by P2X7 in macrophages. (C) 2008 Elsevier Inc. All rights reserved.

Effect of a Pool of Peptides Isolated from Crotalus durissus terrificus (South American Rattlesnake) Venom on Glucose Levels of Mice Fed on a High-Fat Diet

This study investigated the effect of a pool of peptides, isolated from venom of Crotalus durissus terrificus (South American rattlesnake) on glucose concentration in C57BL/6 mice fed on a high-fat diet for 6 weeks. The pool of peptides (molecular mass around of 10 kDa) was obtained using a MidJet apparatus with a cartridge of 10 KDa. The peptide pool was injected intraperitoneally in mice in a single dose (0.5 mg/animal) or multiple doses (0.2 mg/dose). After predetermined times (30, 60, 90 and 120 min) post injections, venous blood samples were collected for enzymatic measurement of serum glucose using a commercial glucose kit (glucose oxidase method). High-fat fed mice showed an increase in blood glucose concentration, in comparison with mice fed on the chow diet. Thirty minutes after a single dose of the peptide pool, high-fat fed animals showed a significant decrease (similar to 47%) in glycemia. However, the glucose level increased again at 60 and 120 min. Conversely, after multiple injections of the pool of peptides administered every 30 min, the blood glucose concentration in the high-fat mice was significantly decreased (similar to 37%) and remained at low levels until 120 min. These results suggest that the tested pool of peptides from Crotalus durissus terrificus contained a peptide (or peptides) with a beneficial role on glucose-lowering action of high-fat fed mice.

The effects of Australian tall poppy attitudes on American value based leadership theory

A survey study of twenty-two Australian CEOs and their subordinates assessed relationships between Australian leader motives, Australian value based leader behaviour, subordinate tall poppy attitudes and subordinate commitment, effectiveness, motivation and satisfaction (CEMS). On the whole, the results showed general support for value based leadership processes. Subsequent regression analyses of the second main component of Value Based Leadership Theory, value based leader behaviour, revealed that the collectivistic, inspirational, integrity and visionary behaviour sub-scales of the construct were positively related with subordinate CEMS. Although the hypothesis that subordinate tall poppy attitudes would moderate value based leadership processes was not clearly supported, subsequent regression analyses found that subordinate tall poppy attitudes were negatively related with perceptions of value based leader behaviour and CEMS. These findings suggest complex relationships between the three constructs, and the proposed model for the Australian context is accordingly amended. Overall, the research supports the need to consider cultural-specific attitudes in management development.

Insufficiently active Australian college students: Perceived personal, social, and environmental influences

Background. A sustainable pattern of participation in physical activity is important in the maintenance of health and prevention of disease, College students are in transition from an active youth to a more sedentary adult behavior pattern. Methods. We assessed self-reported physical activity and other characteristics in a sample of 2,729 male and female students (median age was 20 years) recruited from representative courses and year levels at four Australian College campuses. They were categorized as sufficiently or insufficiently active, using estimates of energy expenditure (kcal/week) derived from self-reported physical activity, Personal factors (self-efficacy, job status, enjoyment), social factors (social support from family/friends), and environmental factors (awareness of facilities, gym membership) were also assessed. Results. Forty-seven percent of females and 32% of males were insufficiently active. For females, the significant independent predictors of being insufficiently active were lower social support from family and friends, lower enjoyment of activity, and not working. For males, predictors were lower social support from family and friends, lower enjoyment of activity, and being older. Conclusions. Factors associated with physical activity participation (particularly social support from family and friends) can inform physical activity strategies directed at young adults in the college setting. (C) 1999 American Health Foundation and Academic Press.

Structure-activity studies of conantokins as human N-methyl-D-aspartate receptor modulators

The activities of conantokin-G (con-G), conantokin-T (con-T), and several novel analogues have been studied using polyamine enhancement of [H-3]MK-801 binding to human glutamate-N-methyl-D-aspartate (NMDA) receptors, and their structures have been examined using CD and H-1 NMR spectroscopy. The potencies of con-G[A7], con-G, and con-T as noncompetitive inhibitors of spermine-enhanced [H-3]MK-801 binding to NMDA receptor obtained from human brain tissue are similar to those obtained using rat brain tissue. The secondary structure and activity of con-G are found to be highly sensitive to amino acid substitution and modification. NMR chemical shift data indicate that con-G, con-G[D8,D17], and con-G[A7] have similar conformations in the presence of Ca2+. This consists of a helix for residues 2-16, which is kinked in the vicinity of Gla10. This is confirmed by 3D structure calculations on con-G[A7]. Restraining this helix in a linear form (i.e., con-G[A7,E10-K13]) results in a minor reduction in potency. Incorporation of a 7-10 salt-bridge replacement (con-G[K7-E10]) prevents helix formation in aqueous solution and produces a peptide with low potency. Peptides with the Leu5-Tyr5 substitution also have low potencies (con-G[Y5,A7] and con-G[Y5,K7]) indicating that Leu5 in con-G is important for full antagonist behavior. We have also shown that the Gla-Ala7 substitution increases potency, whereas the Gla-Lys7 substitution has no effect. Con-G and con-G[K7] both exhibit selectivity between NMDA subtypes from mid-frontal and superior temporal gyri, but not between sensorimotor and mid-frontal gyri. Asn8 and/or Asn17 appear to be important for the ability of con-G to function as an inhibitor of polyamine-stimulated [3H]MK-801 binding, but not in maintaining secondary structure. The presence of Ca2+ does not increase the potencies of con-G and con-T for NMDA receptors but does stabilize the helical structures of con-G, con-G[D8,D17], and, to a lesser extent, con-G[A7]. The NMR data support the existence of at least two independent Ca2+-chelating sites in con-G, one involving Gla7 and possibly Gla3 and the other likely to involve Gla10 and/or Gla14.

Plant latex and first-instar monarch larval growth and survival on three North American milkweed species

First-instar larvae of the monarch butterfly, Danaus plexippus, a milkweed specialist, generally grew faster and survived better on leaves when latex flow was reduced by partial severance of the leaf petiole. The outcome depended on milkweed species and was related to the amount of latex produced. The outcome also may be related to the amount of cardenolide produced by the plants as a potential chemical defense against herbivory. Growth was more rapid, but survival was similar on partially severed compared with intact leaves of the high-latex/low-cardenolide milkweed, Asclepias syriaca, whereas both growth and survival were unaffected on the low-latex/low-cardenolide milkweed A. incarnata. On the low-latex/low-cardenolide milkweed A. tuberosa, both growth and survival of larvae were only marginally affected. These results contrast sharply to previous results with the milkweed, A. humistrata, in Florida, which has both high latex and high cardenolide. Larval growth and survival on A. humistrata were both increased by partially severing leaf petioles. Larval growth rates among all four milkweed species on leaves with partially severed petioles were identical, suggesting that latex and possibly the included cardenolides are important in first-instar monarch larval growth, development, and survivorship.

Novel murine myeloid cell lines that exhibit a differentiation switch in response to IL-3 or GM-CSF, or to different constitutively active mutants of the CM-CSF receptor beta subunit

Several activating mutations have recently been described in the common beta subunit for the human interleukin(IL)-3, IL-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors (h beta c), Two of these, FI Delta and 1374N, result, respectively, in a 37-amino acid duplication and an isoleucine-to-asparagine substitution in the extracellular domain. A third, V449E, leads to valine-to-glutamic acid substitution in the transmembrane domain. Previous studies have shown that when expressed in murine hemopoietic cells in vitro, the extracellular mutants can confer factor independence on only the granulocyte-macrophage lineage while the transmembrane mutant can do so to all cell types of the myeloid and erythroid compartments. To further study the signaling properties of the constitutively active hpc mutants, we have used novel murine hemopoietic cell lines, which we describe in this report. These lines, FDB1 and FDB2, proliferate in murine IL-3 and undergo granulocyte-macrophage differentiation in response to murine GM-CSF, We find that while the transmembrane mutant, V449E, confers factor-independent proliferation on these cell lines, the extracellular hpc mutants promote differentiation. Hence, in addition to their ability to confer factor independence on distinct cell types, transmembrane and extracellular activated h beta c mutants deliver distinct signals to the same cell type. Thus, the FDB cell lines, in combination with activated h beta c mutants, constitute a powerful new system to distinguish between signals that determine hemopoietic proliferation or differentiation. (C) 2000 by The American Society of Hematology.

Percolative fragmentation of char particles during gasification

Percolative fragmentation was confirmed to occur during gasification of three microporous coal chars. Indirect evidence obtained by the variation of electrical resistivity (ER) with conversion was supported by direct observation of numerous fragments during gasification. The resistivity increases slowly at low conversions and then sharply after a certain conversion value, which is a typical percolation phenomenon suggesting the occurrence of internal fragmentation at high conversion. Two percolation models are applied to interpret the experimental data and determine the percolation threshold. A percolation threshold of 0.02-0.07 was found, corresponding to a critical conversion of 92-96% for fragmentation. The electrical resistivity variation at high conversions is found to be very sensitive to diffusional effects during gasification. Partially burnt samples with a narrow initial particle size range were also observed microscopically, and found to yield a large number of small fragments even when the particles showed no disintegration and chemical control prevailed. It is proposed that this is due to the separation of isolated clusters from the particle surface. The particle size distribution of the fragments was essentially independent of the reaction conditions and the char type, and supported the prediction by percolation theory that the number fraction distribution varies linearly with mass in a log-log plot. The results imply that perimeter fragmentation would occur in practical combustion systems in which the reactions are strongly diffusion affected.