Direct versus indirect facilitation (herbivore mediated) among woody plants in a semiarid Chaco forest: A spatial association approach

In arid environments, direct facilitation (microhabitat amelioration) and indirect facilitation (‘associational resistance’ via protection from herbivory) among plants of different species may act simultaneously. Little is known about their relative effects. One way to disentangle the effects is by evaluating spatial associations. We examined the relative importance of these two mechanisms of facilitation in the semiarid Chaco vegetation of north‐central Argentina, through an eight‐way observational study in which we quantified the degree of spatial association between saplings of each of two key tree species, Schinopsis lorentzii (Anacardiaceae) and Aspidosperma quebracho‐blanco (Apocynaceae), with shrub neighbours either possessing spines or without spines and in both an ungrazed site and a site with a long history of cattle grazing. We analysed data across 400 subparcels at each site with spatial analysis by distance indices. Saplings of both tree species showed positive spatial associations with spiny shrubs in the grazed site but not in the ungrazed site, and never with non‐spiny shrubs. This result suggests that spiny shrubs may indeed provide associational resistance for saplings of key tree species in grazed habitats in these dry subtropical forests, that is, that indirect facilitation may predominate over direct facilitation. If confirmed by experimental studies, this result can have implications for the silvopastoral management of rapidly expanding ranches in the semiarid Chaco, where current practice includes the near elimination of native shrubs.     

Association of 25-Hydroxyvitamin D status and genetic variation in the vitamin D metabolic pathway with FEV1 in the Framingham Heart Study

Background

Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.

Methods

We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV₁) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV₁ in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV₁ in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.

Results

We found a positive cross-sectional association between 25(OH)D and FEV₁ in FHS Offspring and Third Generation participants (P = 0.004). There was little or no association between 25(OH)D and longitudinal change in FEV₁ in Third Generation participants (P = 0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV₁ (gene-based P < 0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV₁ in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P = 0.09).

Conclusions

Serum 25(OH)D status was associated with cross-sectional FEV₁, but not longitudinal change in FEV₁. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV₁ and is a promising candidate gene for further studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0238-y) contains supplementary material, which is available to authorized users.     

Alpha sarcoglycan is required for FGF-dependent myogenic progenitor cell proliferation in vitro and in vivo

Mice deficient in α-sarcoglycan (Sgca-null mice) develop progressive muscular dystrophy and serve as a model for human limb girdle muscular dystrophy type 2D. Sgca-null mice suffer a more severe myopathy than that of mdx mice, the model for Duchenne muscular dystrophy. This is the opposite of what is observed in humans and the reason for this is unknown. In an attempt to understand the cellular basis of this severe muscular dystrophy, we isolated clonal populations of myogenic progenitor cells (MPCs), the resident postnatal muscle progenitors of dystrophic and wild-type mice. MPCs from Sgca-null mice generated much smaller clones than MPCs from wild-type or mdx dystrophic mice. Impaired proliferation of Sgca-null myogenic precursors was confirmed by single fiber analysis and this difference correlated with Sgca expression during MPC proliferation. In the absence of dystrophin and associated proteins, which are only expressed after differentiation, SGCA complexes with and stabilizes FGFR1. Deficiency of Sgca leads to an absence of FGFR1 expression at the membrane and impaired MPC proliferation in response to bFGF. The low proliferation rate of Sgca-null MPCs was rescued by transduction with Sgca-expressing lentiviral vectors. When transplanted into dystrophic muscle, Sgca-null MPCs exhibited reduced engraftment. The reduced proliferative ability of Sgca-null MPCs explains, at least in part, the severity of this muscular dystrophy and also why wild-type donor progenitor cells engraft efficiently and consequently ameliorate disease.     

Microsatellite Markers Reveal Genetic Variation within Sclerotinia sclerotiorum Populations in Irrigated Dry Bean Crops in Brazil

Microsatellites are powerful markers to infer population genetic parameters. We used 10 microsatellite loci to characterize the genetic diversity and structure of 79 samples of Sclerotinia sclerotiorum isolated from four Brazilian dry bean populations and observed that eight of them were polymorphic within populations. We identified 102 different haplotypes ranging from 6 to 18 per locus. Analyses based on genetic diversity and fixation indices indicated variability among and within populations of 28.79% (F_ST = 28793) and 71.21%, respectively. To examine genetic relatedness among S. sclerotiorum isolates, we used internal spacer (ITS1‐5.8S‐ITS2) restriction fragment length polymorphism (PCR‐RFLP) and sequencing analysis. PCR‐RFLP analysis of these regions failed to show any genetic differences among isolates. However, we detected variability within the sequence, which does not support the hypothesis of clonal populations within each population. High variability within and among populations may indicate the introduction of new genotypes in the areas analysed, in addition to the occurrence of clonal and sexual reproduction in the populations of S. sclerotiorum in the Brazilian Cerrado.     

Site-specific immobilization of a (His)6-tagged acetylcholinesterase on nickel nanoparticles for highly sensitive toxicity biosensors

This paper reports site-specific affinity immobilization of (His)6-tagged acetylcholinesterase (AChE) onto Ni/NiO nanoparticles for the development of an electrochemical screen-printed biosensor for the detection of organophosphate pesticides. The method is based on the specific affinity binding of the His-tagged enzyme to oxidized nickel nanoparticle surfaces in the absence of metal chelators. This approach allows stable and oriented attachment of the enzyme onto the oxidized nickel through the external His residue in one-step procedure, allowing for fast and sensitive detection of paraoxon in the concentration range from 10⁻⁸ to 10⁻¹³ M. A detection limit of 10⁻¹² M for paraoxon was obtained after 20 min incubation. This method can be used as a generic approach for the immobilization of other His-tagged enzymes for the development of biosensors.     

Anti-tumour and anti-angiogenetic effects of zoledronic acid on human non-small-cell lung cancer cell line

Objectives: Although emerging data suggest that zoledronic acid (Zol) may have different anti‐tumour activities against a broad range of cancers, its effects on lung cancer remain largely unknown. The aim of this study was to evaluate in vitro the anti‐tumoural and anti‐angiogenetic effect of zoledronic acid in non‐small‐cell lung cancer (NSCLC) cells. Material and methods: We treated A549 NSCLC cells with zoledronic acid to investigate survival, cell cycle activity, anti‐angiogenic activity and apoptotic responses to it. Results: We observed that highest Zol concentration (100 μm ) caused arrest in G1 phase of the cell cycle and also induced different percentages of apoptosis in presence (0.9% versus 4.4%) or absence (2.4% versus 28.5%) of serum (P = 0.0001). Zol concentration from 5 to 100 μm for 2 days induced significant concentration‐dependent cell death in adherent cells. Furthermore, Zol (10–100 μm ) induced dose‐dependent reduction both of mRNA and protein expression of VEGF associated with parallel decrease in VEGF secretion in the culture medium. Conclusion: Taken together, these results support a possible anti‐cancer and anti‐angiogenetic activity of Zol. Our data may not only provide a basis for the clinical use of this drug as preventive agent of bone metastases but also suggest that Zol deserves attention as an anti‐cancer agent in non‐small‐cell lung cancer.     

Amyrin esters induce cell death by apoptosis in HL-60 leukemia cells

Four derivatives of an α,β-amyrin mixture were synthesized by acylation with appropriate anhydrides. The structures of the compounds were confirmed by means of IR and (1)H and (13)C NMR. The compounds were screened for cytotoxic activity using four human tumor cell lines (HL-60, MDAMB-435, SF-295 and HCT-8) and normal peripheral blood mononuclear cells (PBMC). 3-O-Carboxymaleinate of α,β-amyrin (3a/3b) were found to be the only active compounds of the series (high cytotoxicity), showing IC(50) values ranging from 1.8 to 3μM. In PBMC, 3a/3b were not toxic, suggesting selectivity for tumor cells. To better understand the mechanism of action involved in the cytotoxicity of 3a/3b, HL-60 cells treated with 3a/3b were examined for morphological changes, DNA fragmentation, cell cycle perturbation, externalization of phosphatidylserine and activation of caspases 3/7, with doxorubicin serving as the positive control. The results indicate that the cytotoxicity of 3a/3b involves the induction of cell death by apoptosis.     

Cl-IB-MECA enhances TNF-α release in peritoneal macrophages stimulated with LPS

Adenosine receptor A3 (A3R) belongs to the Gi/Gq-coupled receptor family, that leads to the intracellular cAMP reduction and intracellular calcium increase, respectively. A3R is widely expressed and it can play a crucial role in many patho-physiological conditions, including inflammation. Here we investigate the effect of Cl-IB-MECA, A3R agonist, on the production of TNF-α. We found that Cl-IB-MECA enhances LPS-induced TNF-α release in peritoneal macrophages. This effect is reduced by MRS1191, A3R antagonist and by forskolin, activator of adenylyl cyclase. pIκBα increased in LPS+Cl-IB-MECA-treated macrophages, while total IκB kinase-β (IKKβ) reduced. Indeed, p65NF-κB nuclear translocation increased in cells treated with LPS+Cl-IB-MECA. Moreover, IMD 0354, IKKβ inhibitor, significantly abrogated the effect of Cl-IB-MECA on TNF-α release. Inhibition of protein kinase C (PKC) significantly reduced Cl-IB-MECA-induced TNF-α release in LPS-stimulated macrophages. Furthermore, LY-294002, PI3K inhibitor, reduced the TNF-α production enhanced by Cl-IB-MECA, although the phosphorylation status of Akt did not change in cells treated with LPS+Cl-IB-MECA than LPS alone. In summary, these data show that Cl-IB-MECA is able to enhance TNF-α production in LPS-treated macrophages in an NF-κB- dependent manner.