Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

Background

The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl₄) in rats.

Results

The animals were divided into four groups with six rats in each group. CCl₄ (0.125 mL kg^-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg^-1 body wt.) was given by gavage 7 days before the CCl₄ injection. Bixin prevented the liver damage caused by CCl₄, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl₄ by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.

Conclusion

Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl₄ is related to the antioxidant activity of the compound.     

Ethylene Modulates the Developmental Plasticity and the Growth Balance Between Shoot and Root Systems in the In Vitro Grown Epiphytic Orchid Catasetum fimbriatum

The epiphytic habitat is potentially one of the most stressful environments for plants, making the effective developmental control in response to external cues critical for epiphyte survival. Because ethylene mediates several abiotic stresses in plants, here, we have examined the ethylene influence in both shoot and root systems of the epiphytic orchid Catasetum fimbriatum. Under controlled conditions, ethylene production was quantified during an entire growth cycle of C. fimbriatum development in vitro, while treatments modulating either ethylene concentration or perception were carried out over the early growth phase of these plants. After treatments, growth measurements and histological features were studied in both shoot and root tissues. Ethylene production showed a decreasing trend over the period of organ elongation; however, it increased considerably when leaves were shed, and a new axillary bud was initiating. The early exposure of young plants to higher concentrations of ethylene triggered morphogenic responses that included root hair formation instead of velamen, and a combination of inhibitory effects (decreases in both stem enlargement and cellular/organ elongation) and inductive effects (increases in leaf and root formation, bud initiation and cellular thickening) on plant growth, which favored biomass allocation to roots. Conversely, inhibition of ethylene perception over the plant growth phase generally resulted in the opposite morphogenic responses. Our data indicate that periodic variations in ethylene concentration and/or sensitivity seem to modulate several developmental features in shoot and root systems of C. fimbriatum which could have adaptive significance during the growing phase of this epiphytic orchid.     

Genetic diversity,spatial genetic structure and realised seed and pollen dispersal of Himatanthus drasticus (Apocynaceae) in the Brazilian savanna

We assessed the pollen and seed dispersal patterns, genetic diversity, inbreeding and spatial genetic structure of Himatanthus drasticus (Apocynaceae), a tree native to the Brazilian Savanna (Cerrado) that is heavily exploited for its medicinal latex. The study was conducted in the Araripe National Forest, Ceará State, Brazil. Within a one-hectare plot, samples were collected from all adult trees, adult trees located in the immediate vicinity of the plot, and seedlings. All sampled individuals were mapped and genotyped using microsatellite markers. High levels of polymorphism and significant levels of inbreeding were found, which indicates that self-fertilisation and mating among relatives occur in this population. Both the adults and seedlings had significant spatial genetic structure up to ~40 m and our results confirmed the occurrence of isolation by distance. Pollen and seeds were dispersed over short distances and immigration of pollen and seeds into the plot was estimated at 13 and 9 %, respectively. Taking into consideration the degree of inbreeding, relatedness, intrapopulation spatial genetic structure and pollen dispersal distance, we recommend collecting seeds from a large number of trees spaced at least 150 m apart to avoid collecting seeds from related individuals and an overlap of pollen pools among seed trees.     

Regulation of TrkB receptor translocation to lipid rafts by adenosine A2A receptors and its functional implications for BDNF-induced regulation of synaptic plasticity

Brain-derived neurotrophic factor (BDNF) signalling is critical for neuronal development and transmission. Recruitment of TrkB receptors to lipid rafts has been shown to be necessary for the activation of specific signalling pathways and modulation of neurotransmitter release by BDNF. Since TrkB receptors are known to be modulated by adenosine A_2A receptor activation, we hypothesized that activation of A_2A receptors could influence TrkB receptor localization among different membrane microdomains. We found that adenosine A_2A receptor agonists increased the levels of TrkB receptors in the lipid raft fraction of cortical membranes and potentiated BDNF-induced augmentation of phosphorylated TrkB levels in lipid rafts. Blockade of the clathrin-mediated endocytosis with monodansyl cadaverine (100 μM) did not modify the effects of the A_2A receptor agonists, but significantly impaired BDNF effects on TrkB recruitment to lipid rafts. The effect of A_2A receptor activation in TrkB localization was mimicked by 5 μM forskolin, an adenylyl cyclase activator. Also, it was blocked by the PKA inhibitors Rp-cAMPs and PKI-(14-22) and by the Src-family kinase inhibitor PP2. Moreover, removal of endogenous adenosine or disruption of lipid rafts reduced BDNF stimulatory effects on glutamate release from cortical synaptosomes. Lipid raft integrity was also required for the effects of BDNF upon hippocampal long-term potentiation at CA1 synapses. Our data demonstrate, for the first time, a BDNF-independent recruitment of TrkB receptors to lipid rafts, induced by the activation of adenosine A_2A receptors, with functional consequences for TrkB phosphorylation and BDNF-induced modulation of neurotransmitter release and hippocampal plasticity.     

Mechanisms of phosphate solubilization by fungal isolates when exposed to different P sources

The use of phosphate-solubilizing fungi is a promising biotechnological strategy in the management of phosphorus (P) fertilization, as it enables the utilization of rock phosphates (RP) or the recovery of P fixed in soil particles. The objective of our study was to evaluate fungal isolates for mechanisms of solubilization of P-bearing compounds, such as AlPO₄, FePO₄, Ca₃(PO₄)₂, Araxá RP, and Catalão RP. Four fungal isolates obtained from Brazilian soils were characterized in liquid media: Aspergillus niger FS1, Penicillium canescens FS23, Eupenicillium ludwigii FS27, and Penicillium islandicum FS30. A. niger FS1 was the only isolate able to solubilize all of the P sources, solubilizing 71, 36, 100, and 14 % of the P from AlPO₄, FePO₄, Ca₃(PO₄)₂, and RPs, respectively. Medium acidification was an effective solubilization mechanism, particularly for Ca₃(PO₄)₂. The other P sources were mainly solubilized through organic acids produced by the fungi. Oxalic acid, produced exclusively by A. niger FS1, and citric acid were decisive factors in the solubilization of AlPO₄ and FePO₄. Penicillium isolates produced more gluconic acid than A. niger FS1 in all treatments. However, this higher production did not result in higher solubilization for any of the P sources, showing that gluconic acid contributes little to the solubilization of the P sources evaluated. The higher capacity of medium acidification and the production of organic acids with stronger metal-complexation activity are characteristics that confer to A. niger FS1 a wider action on insoluble P sources. Consequently, this isolate qualifies as a promising candidate for application in the management of P fertilization.     

Ultrastructure and Immunofluorescence of the midgut of Bombus morio (Hymenoptera: Apidae: Bombini)

Bumblebees are widely distributed across the world and have great economic and ecological importance as pollinators in the forest as well as in agriculture. The insect midgut consists of three cell types, which play various important roles in digestion, absorption, and hormone production. The present study characterized the anterior and posterior midgut regions of the bumblebee, Bombus morio. The digestive, regenerative and endocrine cells in the midgut showed regional differences in their number, nuclear size, as well as the size of the striated border. Ultrastructurally, the digestive cells contained many mitochondria and long microvilli; however, in the anterior midgut region, these cells showed dilated basal labyrinths with a few openings for the hemocoel, whereas the labyrinths of the basal posterior region remained inverse characteristics. Thus, the characterization of the midgut of B. morio supported an ecto-endoperitrophic circulation, contributing to a better understanding of the digestive process in this bee.     

Quantitative analysis of race-specific resistance to Colletotrichum lindemuthianum in common bean

Molecular genetic maps continue to play a major role in breeding of crop species. The common bean genetic map of the recombinant inbred line population IAC-UNA × CAL 143 (UC) has been used to detect loci controlling important agronomic traits in common bean. In the current study, new microsatellite markers were added to the UC map and the linkage analysis was refined using current genomic resources of common bean, in order to identify quantitative resistance loci (QRL) associated with different races of the anthracnose pathogen. A single race inoculation was conducted in greenhouse using four plants per plot. Both race-specific and joint-adjusted disease severity means, obtained from linear-mixed model, were used to perform multiple interval mapping (MIM) and multi-trait MIM (MTMIM). In total, 13 and 11 QRL were identified by MIM and MTMIM analyses, respectively; with nine being observed in both analyses. ANT02.1^UC and ANT07.1^UC showed major effects on resistance both for MIM and MTMIM. Common major QRL for resistance to the three anthracnose races were expected, since high genetic pairwise-correlation was observed between the race-specific and joint-adjusted disease severity means. Therewith, both ANT02.1 and ANT07.1 can be regarded as valuable targets for marker-assisted selection; and so, putative genes potentially involved in the resistance response were identified in these QRL regions. Minor effect QRL were also observed, showing differential affects either on race-specific or multi-trait analyses and may play a role on durable horizontal resistance. These results contribute to a better understanding of the host-pathogen interaction and to breeding for enhancing resistance to Colletotrichum lindemuthianum in common bean.