Increased Receptor for Advanced Glycation Endproducts Immunocontent in the Cerebral Cortex of Vitamin A-Treated Rats

Vitamin A, beyond its biological role, is an alternative choice in treating some life threatening pathologies, for instance leukemia and immunodeficiency. On the other hand, vitamin A therapy at moderate to high doses has caused concern among public health researchers due to the toxicological aspect resulting from such habit. It has been described hepatotoxicity, cognitive disturbances and increased mortality rates among subjects ingesting increased levels of vitamin A daily. Then, based on the previously reported data, we investigated here receptor for advanced glycation endproducts (RAGE) immunocontent and oxidative damage levels in cerebral cortex of vitamin A-treated rats at clinical doses (1,000–9,000 IU/kg day⁻¹). RAGE immunocontent, as well as oxidative damage levels, were observed increased in cerebral cortex of vitamin A-treated rats. Whether increased RAGE levels exert negative effects during vitamin A supplementation it remains to be investigated, but it is very likely that deleterious consequences may arise from such alteration.     

Patterns of genetic diversity in southern and southeastern Araucaria angustifolia (Bert.) O. Kuntze relict populations

Habitat fragmentation and a decrease in population size may lead to a loss in population genetic diversity. For the first time, the reduction in genetic diversity in the northernmost limit of natural occurence (southeastern Brazil) of Araucaria angustifolia in comparison with populations in the main area of the species continuous natural distribution (southern Brazil), was tested. The 673 AFLPs markers revealed a high level of genetic diversity for the species (Ht = 0.27), despite anthropogenic influence throughout the last century, and a decrease of H in isolated populations of southeastern Brazil (H = 0.16), thereby indicating the tendency for higher genetic diversity in remnant populations of continuous forests in southern Brazil, when compared to natural isolated populations in the southeastern region. A strong differentiation among southern and southeastern populations was detected (AMOVA variance ranged from 10%-15%). From Bayesian analysis, it is suggested that the nine populations tested form five "genetic clusters" (K = 5). Five of these populations, located in the northernmost limit of distribution of the species, represent three "genetic clusters". These results are in agreement with the pattern of geographic distribution of the studied populations.     

Acute exercise boosts cell proliferation and the heat shock response in lymphocytes: correlation with cytokine production and extracellular-to-intracellular HSP70 ratio

Exercise stimulates immune responses, but the appropriate “doses” for such achievements are unsettled. Conversely, in metabolic tissues, exercise improves the heat shock (HS) response, a universal cytoprotective response to proteostasis challenges that are centred on the expression of the 70-kDa family of intracellular heat shock proteins (iHSP70), which are anti-inflammatory. Concurrently, exercise triggers the export of HSP70 towards the extracellular milieu (eHSP70), where they work as pro-inflammatory cytokines. As the HS response is severely compromised in chronic degenerative diseases of inflammatory nature, we wondered whether acute exercise bouts of different intensities could alter the HS response of lymphocytes from secondary lymphoid organs and whether this would be related to immunoinflammatory responses. Adult male Wistar rats swam for 20 min at low, moderate, high or strenuous intensities as per an overload in tail base. Controls remained at rest under the same conditions. Afterwards, mesenteric lymph node lymphocytes were assessed for the potency of the HS response (42 °C for 2 h), NF-κB binding activity, mitogen-stimulated proliferation and cytokine production. Exercise stimulated cell proliferation in an “inverted-U” fashion peaking at moderate load, which was paralleled by suppression of NF-κB activation and nuclear location, and followed by enhanced HS response in relation to non-exercised animals. Comparative levels of eHSP70 to iHSP70 (H-index) matched IL-2/IL-10 ratios. We conclude that exercise, in a workload-dependent way, stimulates immunoinflammatory performance of lymphocytes of tissues far from the circulation and this is associated with H-index of stress response, which is useful to assess training status and immunosurveillance balance.     

MODULAR: software for the autonomous computation of modularity in large network sets

Many ecological systems can be represented as networks of interactions. A key feature in these networks is their organization into modules, which are subsets of tightly connected elements. We introduce MODULAR to perform rapid and autonomous calculation of modularity in network sets. MODULAR reads a set of files representing unipartite or bipartite networks, and identifies modules using two different modularity metrics widely used in the ecological networks literature. To estimate modularity, the software offers five optimization methods to the user. The software also includes two null models commonly used in studies of ecological networks to verify how the degree of modularity differs from two distinct theoretical benchmarks.     

Genetic dissection of Al tolerance QTLs in the maize genome by high density SNP scan

Background

Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.

Results

Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al³⁺ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.

Conclusions

High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users.     

Susceptibility of different populations of ticks to entomopathogenic fungi

This study aimed to evaluate the in vitro effect of the entomopathogenic fungi Metarhizium anisopliae sensu lato (s.l.) and Beauveria bassiana sensu lato (s.l.) on two distinct populations of Rhipicephalus microplus, from two different experimental farms. Bioassays were performed with engorged females, eggs and larvae. Fungal infection was evaluated based on biological parameters of treated engorged females, percentage of hatch from treated eggs, and percentage of mortality and mean lethal time (LT90) of treated larvae. When the treatments were compared between the two populations, there were significant differences in the following parameters: pre-oviposition period, hatching period and egg production index. Moreover, the results showed that B. bassiana s.l., isolate Bb 986, was more virulent than M. anisopliae s.l., isolate 959, for engorged females, showing a control percentage of 49%. In the bioassay with eggs, the hatching percentage ranged from 3.1% to 49.5% in one population and from 3.4% to 42.7% in the other, with no significant difference between the two populations. In the bioassay with unfed larvae, the mortality percentage ranged from 91.8% to 98.7% in one population and from 71.0% to 94.0% in the other. The LT(90) varied from 19.52 to 27.51 days in one of the populations and 22.89 to 37.31 days in the other. These results suggest that populations of R. microplus show distinct variation in their susceptibility to B. bassiana s.l. and M. anisopliae s.l.     

Comparison Between Etest and Broth Microdilution Methods for Testing Itraconazole-Resistant <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> Susceptibility to Antifungal Combinations

The checkerboard broth microdilution assay (BMD) is the most frequently used method for the in vitro evaluation of drug combinations. However, its use to evaluate the effect of antifungal drugs on filamentous fungi is sometimes associated with endpoint-reading difficulties, and different degrees of interaction are assigned to the same drug combination. We evaluated combinations of the azoles, itraconazole, posaconazole, and voriconazole, with the echinocandins, anidulafungin, caspofungin, and micafungin, against 15 itraconazole-resistant Aspergillus fumigatus clinical strains via the checkerboard BMD and Etest assay. Readings after 24 and 48 h, considering the two reading endpoints, the minimum inhibitory concentration (MIC) and minimum effective concentration (MEC), were performed for both methods. Our results showed that the correlation coefficients between the BMD and Etest methods were quite diverse to the drug combinations tested. The highest correlation coefficients of the Etest with the BMD assays (MEC and MIC reading) were the Etest-MIC reading at 24 h and the Etest-MEC reading at 48 h. Improvements in experimental conditions may increase the correlation between the two methods and ensure that Etest assay can be safely used in the evaluation of antifungal combinations against Aspergillus species.     

Using genetic diversity and mating system parameters estimated from genetic markers to determine strategies for the conservation of <Emphasis Type="Italic">Araucaria angustifolia</Emphasis> (Bert.) O. Kuntze (Araucariaceae)

In order to understand the impacts of forest fragmentation on Araucaria angustifolia populations, we evaluated the genetic diversity and mating system using SSR markers and open-pollinated seeds from four populations of varying sizes and spatial isolation, in and around one of the best-conserved Araucaria Forest remnants in Southern Brazil. The four population types of A. angustifolia include: (1) a continuous forest; (2) a physically isolated cluster located 2 km from the continuous forest; (3) an open population in a field located between the cluster and continuous forest; and (4) a fragment on a private property located 5 km from the cluster. Approximately 28 seeds were collected from ten reproductive trees in each population. We found higher amounts of alleles (113) and exclusive alleles (25) in the continuous forest than in the other populations. The multilocus paternity correlation was significantly higher and effective number of pollen donors was significantly lower in the private population, decreasing the diversity and consequently the variance effective size of families sampled from that population. However, despite its isolation from the other studied fragments, the private population had the second highest number of alleles as well as unique alleles from the other populations. Therefore, strategies for A. angustifolia conservation should focus not only on larger populations, such as those found in protected areas, but also include smaller and isolated fragments on private properties as these populations are able to maintain high levels of genetic diversity and functional connectivity between isolated stands across a landscape.