Minimizing the biodiversity impact of Neotropical oil palm development

Oil palm agriculture is rapidly expanding in the Neotropics, at the expense of a range of natural and seminatural habitats. A key question is how this expansion should be managed to reduce negative impacts on biodiversity. Focusing on the Llanos of Colombia, a mixed grassland–forest system identified as a priority zone for future oil palm development, we survey communities of ants, dung beetles, birds and herpetofauna occurring in oil palm plantations and the other principal form of agriculture in the region – improved cattle pasture – together with those of surrounding natural forests. We show that oil palm plantations have similar or higher species richness across all four taxonomic groups than improved pasture. For dung beetles, species richness in oil palm was equal to that of forest, whereas the other three taxa had highest species richness in forests. Hierarchical modelling of species occupancy probabilities indicated that oil palm plantations supported a higher proportion of species characteristic of forests than did cattle pastures. Across the bird community, occupancy probabilities within oil palm were positively influenced by increasing forest cover in a surrounding 250 m radius, whereas surrounding forest cover did not strongly influence the occurrence of other taxonomic groups in oil palm. Overall, our results suggest that the conversion of existing improved pastures to oil palm has limited negative impacts on biodiversity. As such, existing cattle pastures of the Colombian Llanos could offer a key opportunity to meet governmental targets for oil palm development without incurring significant biodiversity costs. Our results also highlight the value of preserving remnant forests within these agricultural landscapes, protecting high biodiversity and exporting avian ‘spill‐over’ effects into oil palm plantations.     

Differences in bacterial diversity of host-associated populations of Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae) in pecan and water hickory

Host‐associated differentiation (HAD) is the presence of genetically divergent, host‐associated populations. It has been suggested that microbial symbionts of insect herbivores may play a role in HAD by allowing their insect hosts to use different plant species. The objective of this study was to document if host‐associated populations of Phylloxera notabilis Pergande (Hemiptera: Phylloxeridae) in pecan and water hickory corresponded with differences in the composition of their associated bacteria. To test this hypothesis, we characterized the symbionts present in P. notabilis associated with these two tree species through metagenomic analyses using 454 sequencing. Differences in bacterial diversity were found between P. notabilis populations associated with pecan and water hickory. The bacteria, Pantoea agglomerans and Serratia marcescens, were absent in the P. notabilis water hickory population, whereas both species accounted for more than 69.72% of bacterial abundance in the pecan population.     

Interplay between RAGE, CD44, and focal adhesion molecules in epithelial-mesenchymal transition of alveolar epithelial cells

Fibrosis of the lung is characterized by the accumulation of myofibroblasts, a key mediator in the fibrogenic reaction. Cumulative evidence indicates that epithelial-mesenchymal transition (EMT), a process whereby epithelial cells become mesenchyme-like, is an important contributing source for the myofibroblast population. Underlying this phenotypical change is a dramatic alteration in cellular structure. The receptor for advanced glycation end-products (RAGE) has been suggested to maintain lung homeostasis by mediating cell adhesion, while the family of ezrin/radixin/moesin (ERM) proteins, on the other hand, serve as an important cross-linker between the plasma membrane and cytoskeleton. In the present investigation, we tested the hypothesis that RAGE and ERM interact and play a key role in regulating EMT-associated structural changes in alveolar epithelial cells. Exposure of A549 cells to inflammatory cytokines resulted in phosphorylation and redistribution of ERM to the cell periphery and localization with EMT-related actin stress fibers. Simultaneously, blockade of Rho kinase (ROCK) signaling attenuated these cytokine-induced structural changes. Additionally, RAGE expression was diminished after cytokine stimulation, with release of its soluble isoform via a matrix metalloproteinase (MMP)-9-dependent mechanism. Immunofluorescence microscopy and coimmunoprecipitation revealed association between ERM and RAGE under basal conditions, which was disrupted when challenged with inflammatory cytokines, as ERM in its activated state complexed with membrane-linked CD44. Dual-fluorescence immunohistochemistry of patient idiopathic pulmonary fibrosis (IPF) tissues highlighted marked diminution of RAGE in fibrotic samples, together with enhanced levels of CD44 and double-positive cells for CD44 and phospho (p)ERM. These data suggest that dysregulation of the ERM-RAGE complex might be an important step in rearrangement of the actin cytoskeleton during proinflammatory cytokine-induced EMT of human alveolar epithelial cells.     

Multimeric system of 99mTc-labeled gold nanoparticles conjugated to c[RGDfK(C)] for molecular imaging of tumor α(v)β(3) expression

Integrin α(V)β(3) plays a critical role in tumor angiogenesis and metastasis. Suitably radiolabeled cyclic RGD peptides can be used for noninvasive imaging of α(V)β(3) expression. The aim of this research was to prepare a multimeric system of technetium-99m-labeled gold nanoparticles conjugated to c[RGDfK(C)] and to evaluate its biological behavior as a potential radiopharmaceutical for molecular imaging of tumor angiogenesis. Hydrazinonicotinamide-GGC (HYNIC-GGC) and c[RGDfK(C)] peptides were synthesized and conjugated to gold nanoparticles (AuNP, 20 nm) by means of spontaneous reaction of the thiol groups of cysteine. The nanoconjugate was characterized by TEM, FT-IR, UV-vis, XPS, and Raman spectroscopy. To obtain (99m)Tc-HYNIC-GGC-AuNP-c[RGDfK(C)] ((99m)Tc-AuNP-RGD), the (99m)Tc-HYNIC-GGC radiopeptide was first prepared and added to 1.5 mL of AuNP solution (1 nM) followed by c[RGDfK(C)] (10 μL, 50 μM) at 18 °C with stirring for 15 min. Radiochemical purity (RP) was determined by size-exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in α(V)β(3) receptor-positive C6 glioma cancer cells. Biodistribution studies were accomplished in athymic mice with C6-induced tumors with blocked and nonblocked receptors, and images were obtained using a micro-SPECT/CT. TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with peptides. RP was 96 ± 2% without postlabeling purification. (99m)Tc-AuNP-RGD showed specific recognition for α(V)β(3) integrins expressed in C6 cells, and 3 h after i.p. administration in mice, the tumor uptake was 8.18 ± 0.57% ID/g. Micro-SPECT/CT images showed evident tumor uptake. (99m)Tc-AuNP-RGD demonstrates properties suitable for use as a target-specific agent for molecular imaging of tumor α(V)β(3) expression.     

Rapid evolution of coral proteins responsible for interaction with the environment

BACKGROUND: Corals worldwide are in decline due to climate change effects (e.g., rising seawater temperatures), pollution, and exploitation. The ability of corals to cope with these stressors in the long run depends on the evolvability of the underlying genetic networks and proteins, which remain largely unknown. A genome-wide scan for positively selected genes between related coral species can help to narrow down the search space considerably. METHODOLOGY/PRINCIPAL FINDINGS: We screened a set of 2,604 putative orthologs from EST-based sequence datasets of the coral species Acropora millepora and Acropora palmata to determine the fraction and identity of proteins that may experience adaptive evolution. 7% of the orthologs show elevated rates of evolution. Taxonomically-restricted (i.e. lineage-specific) genes show a positive selection signature more frequently than genes that are found across many animal phyla. The class of proteins that displayed elevated evolutionary rates was significantly enriched for proteins involved in immunity and defense, reproduction, and sensory perception. We also found elevated rates of evolution in several other functional groups such as management of membrane vesicles, transmembrane transport of ions and organic molecules, cell adhesion, and oxidative stress response. Proteins in these processes might be related to the endosymbiotic relationship corals maintain with dinoflagellates in the genus Symbiodinium. CONCLUSION/RELEVANCE: This study provides a birds-eye view of the processes potentially underlying coral adaptation, which will serve as a foundation for future work to elucidate the rates, patterns, and mechanisms of corals' evolutionary response to global climate change.     

Ursodeoxycholic acid is conjugated with taurine to promote secretin-stimulated biliary hydrocholeresis in the normal rat

Background & Aims

Secretin induces bicarbonate-rich hydrocholeresis in healthy individuals, but not in untreated patients with primary biliary cirrhosis (PBC). Ursodeoxycholic acid (UDCA) – the first choice treatment for PBC – restores the secretin response. Compared with humans, secretin has poor effect in experimental normal-rat models with biliary drainage, although it may elicit hydrocholeresis when the bile-acid pool is maintained. In view of the benefits of UDCA in PBC, we used normal-rat models to unravel the acute contribution of UDCA (and/or taurine-conjugated TUDCA) for eliciting the biliary secretin response.

Methods

Intravascular and/or intrabiliary administration of agonists and inhibitors was performed in normal rats with biliary monitoring. Secretin/bile-acid interplay was analyzed in 3D cultured rat cholangiocytes that formed expansive cystic structures with intralumenal hydroionic secretion.

Results

In vivo, secretin stimulates hydrocholeresis upon UDCA/TUDCA infusion, but does not modify the intrinsic hypercholeretic effect of dehydrocholic acid (DHCA). The former effect is dependent on microtubule polymerization, and involves PKCα, PI3K and MEK pathways, as shown by colchicine (i.p.) and retrograde biliary inhibitors. In vitro, while secretin alone accelerates the spontaneous expansion of 3D-cystic structures, this effect is enhanced in the presence of TUDCA, but not UDCA or DHCA. Experiments with inhibitors and Ca²⁺-chelator confirmed that the synergistic effect of secretin plus TUDCA involves microtubules, intracellular Ca²⁺, PKCα, PI3K, PKA and MEK pathways. Gene silencing also demonstrated the involvement of the bicarbonate extruder Ae2.

Conclusions

UDCA is conjugated in order to promote secretin-stimulated hydrocholeresis in rats through Ae2, microtubules, intracellular Ca²⁺, PKCα, PI3K, PKA, and MEK.     

Plant–Plant and Plant–Topography Interactions on a Rock Outcrop at High Altitude in Southeastern Brazil1

Plant establishment and growth on rocky outcrops in the Itatiaia massif (2400 m a.s.l.), southeastern Brazil, are limited by lack of soil and by freezing temperatures in winter nights. Mat‐forming species of different sizes and shapes on bare rock provide substrate for other plants to establish. The habitat preference of two geophytes, Stevia camporum (Asteraceae) and Alstroemeria foliosa (Alstroemeriaceae), was compared with regard to their association with the type of mat species and distinct rock topographies. The habitat preference of the mat species in regard to topography was also assessed. We found 1706 ramets of S. camporum and 1317 of A. foliosa in 253 vegetation islands ranging in size from 0.005 to 18.097 m². Mat species in these islands were Fernseea itatiaiae, Vriesea itatiaiae (both Bromeliaceae), Pleurostima gounelleana (Velloziaceae) and/or Campylopus pilifer (Dicranaceae) and other mosses. Mat species were segregated by topography. Geophytes were similarly distributed across types of topography but showed negative interspecific association. S. camporum occurred mostly on the moss‐dominated islands, whereas A. foliosa was more common in P. gounelleana islands. We found geophyte co‐occurrence in larger vegetation islands containing both P. gounelleana and mosses as mat species. Thus, the effect of topography on geophyte segregation was indirect, since topography affects mat species distribution, and the geophyte preference for distinct mat species as substrate resulted in their segregation.     

Drosophila wing-spot test for genotoxic assessment of pollutants in water samples from urban and industrial origin

The Caí River (Rio Grande do Sul, Brazil) is an important watercourse that receives large amounts of industrial and untreated municipal discharges in its lower course. We employed the SMART in Drosophila melanogaster to evaluate the genotoxicity of surface waters collected from Caí sites receiving direct sewage discharge: from Montenegro (Km 52) and from S?o Sebasti?o do Caí (Km 78 and 80), and from two sites under the industrial influence (Km 13.6 and 18.6). The genotoxic analysis included three collections: March, June and September 1999, which were tested at crude sample and at 50 and 25% concentrations. Considering the industrial samples from Km 18.6 and 13.6, collected in March, June and September 1999, they were characterized as not having genetic toxicity. The urban samples collected in March--Km 52, 78 and 80--showed a significant increment in the frequencies of total spots. In Km 52 and 78 the genotoxic effect was associated to both mutational and recombinational events, although for Km 80 the increases observed were mainly related to the occurrence of homologous recombination. Moreover, the Km 80 crude sample from June and all the concentrations analyzed for Km 52 in September were also able to induce mitotic recombination. These effects were only observed in the ST cross, demonstrating the genotoxins present in the urban discharges act by direct interaction with the DNA of the somatic cells. The SMART in D. melanogaster was shown to be highly sensitive to detect genotoxic agents present in the aquatic environment, and must be better exploited for monitoring areas under anthropogenic discharges.     

High-nitrogen compost as a medium for organic container-grown crops

Compost was tested as a medium for organic container-grown crops. Nitrogen (N) loss during composting of separated cow manure (SCM) was minimized using high C/N (wheat straw, WS; grape marc, GM) or a slightly acidic (orange peels, OP) additives. N conservation values in the resultant composts were 82%, 95% and 98% for GM-SCM, OP-SCM and WS-SCM, respectively. Physical characteristics of the composts were compatible with use as growing media. The nutritional contribution of the composts was assessed using cherry tomato (Lycopersicon esculantum Mill.) and by means of incubation experiments. Media were either unfertilized or fertilized with guano (sea-bird manure). Plant responses suggest that N availability is the main variable affecting growth. Unfertilized OP-SCM and WS-SCM supplied the N needed for at least 4 months of plant growth. Root-galling index (GI) of tomato roots and number of eggs of the nematode Meloidogyne javanica were reduced by the composts, with the highest reduction obtained by OP-SCM and WS-SCM, at 50% concentrations. These composts, but not peat, reduced the incidence of crown and root-rot disease in tomato as well as the population size of the causal pathogen, Fusarium oxysporum f. sp. radicis-lycopersici.