Karyotype evolution in South American subterranean rodents Ctenomys magellanicus (Rodentia: Octodontidae): chromosome rearrangements and (TTAGGG)n telomeric sequence localization in 2n=34 and 2n=36 chromosomal forms

Ctenomys is the most numerous genus of South American subterranean rodents and one of the most karyotypically diverse clades of mammals known. Ctenomys magellanicus is the southernmost species of the group and the only one living in Isla Grande de Tierra del Fuego (Argentina). This species presents two chromosomal forms, i.e. 2n=34, and 2n=36 (FN=68). Recent studies suggest that genetic divergence between both karyotypic forms resulted from a chromosomal speciation process. In order to identify the chromosomal rearrangement involved in the process of karyotype evolution in this species, we used chromosome banding techniques and fluorescence in situ hybridization with a telomeric probe to metaphase chromosomes of the two chromosomal forms of Ctenomys magellanicus. Chromosome analysis of Giemsa-stained and G-banding preparations showed that Cm34 and Cm36 karyotypes differ in one rearrangement involving chromosomes A9 from Cm34 and B12 and B17 from Cm36. In addition FISH analysis showed that all of the chromosomes from both chromosomal forms exhibit a telomeric-only distribution pattern of the (TTAGGG)n sequence, indicating that none of the chromosomal forms of Ctenomys magellanicus has true telocentric chromosomes. Our results suggest that a chromosome fission event would have occurred during the process of karyotype evolution in this species.     

In Vitro Trypanocidal Activity of Macela (Achyrocline satureioides) Extracts against Trypanosoma evansi

The aim of this study was to verify the trypanocidal effectiveness of aqueous, methanolic, and ethanolic extracts of Achyrocline satureioides against Trypanosoma evansi in vitro. A. satureioides extracts, known as macela, were used on trypomastigotes at different concentrations (1, 5, 10, 50, 100, 500, and 1,000 µg/ml) and exposure times (0, 1, 3, 6, and 9 hr). A dose-dependent effect was observed when the 3 extracts were tested. The concentrations of 1, 5, and 10 µg/ml were not able to kill trypomastigotes until 3 hr after exposure, and the highest concentrations (500 and 1,000 µg/ml) were able to kill all trypomastigotes after 1 hr. When the time of exposure was increased up to 9 hr, the concentrations at 50 and 100 µg/ml were 100% effective to 3 extracts. The chemical analysis of the extracts revealed the presence of flavonoids, a trypanocidal compound already described. Based on the results, we can conclude that the A. satureioides extracts exhibit trypanocidal effects.     

Occurrence of Stiretrus decastigmus (Herrich-Schaeffer) (Hemiptera: Pentatomidae) Preying on Microtheca semilaevis Stal (Coleoptera: Chrysomelidae)

Microtheca semilaevis Stal is a phythophagous insect associated to Brassicaceae, and frequently occurs with other species of beetles, such as Microtheca ochroloma Stal. Despite its importance to organic farmers, there is no information in the Brazilian literature about its natural enemies. Stiretrus decastigmus (Herrich-Schaeffer) was first found and here reported preying an adult of M. semilaevis in Chinese cabbage in Santa Maria, RS, Brazil (29°43??28??S, 53°43??19??W).     

Creatine nanoliposome reverts the HPA-induced damage in complex II–III activity of the rats’ cerebral cortex

Molecular Biology Reports - Phenylketonuria (PKU) is a metabolic disorder accumulating phenylalanine (Phe) and its metabolites in plasma and tissues of the patients. Regardless of the mechanisms,...     

Invasion ecology applied to inoculation of plant growth promoting bacteria through a novel SIMPER-PCA approach

Plant and Soil - Plant growth promoting bacteria (PGPB) have been used on crops for years, but inoculants that are efficient in some locations may not be efficient in others. Here, we applied...     

Relationship Between In Vitro Enhanced Nitrogenase Activity of an Azospirillum brasilense Sp7 Mutant and Its Growth-Promoting Activities In Situ

In this work, we further analyzed an Azospirillum brasilense Sp7 mutant (Sp7::Tn5-33) showing a pleiotrophic phenotype due to a Tn5 insertion into an open reading frame of 840 bp (orf280). The deduced amino acid sequence of this region has high similarity to a family of universal stress proteins. Because the most interesting property exhibited by the Sp7::Tn5-33 mutant was an enhanced in vitro nitrogen fixation activity, we addressed the question of whether it could benefit the host plant. We found that the increased nitrogenase activity at the free-living state of the mutant bacterium was correlated with an increased production of the nitrogenase reductase protein (NifH), in amounts approximately 1.5 times higher than the wild type. The mutant strain exhibited the same level of auxin production and the same colonization pattern of wheat roots as the wild type. We also observed that Sp7::Tn5-33 increased the total plant dry weight, although the N content did not differ significantly between wheat plants inoculated with mutant or wild-type strains.     

Investigations into the Mechanism of 2,3-Dimercaptopropanol Neurotoxicity

2,3 dimercaptopropanol (BAL), is a dithiol chelating agent, used for the treatment of heavy metal intoxication; however, this compound has low therapeutic efficacy and in some situations may cause neurotoxic effects. In experimental models, administration of high doses of BAL produces seizures that culminate in animal death. However, investigations on the modulation of neurotransmitter system(s) involved in BAL-induced seizures are still lacking in the literature. In the present study, the neurotoxicity of BAL, as measured by the manifestation of seizures was examined and the modulation of glutamatergic and GABAergic receptors and ion channels potentially involved in BAL-induced seizures was investigated. The results demonstrated that BAL (18.6 mg/kg) induced seizures and all mice died within one day. GABAergic allosteric modulators (3 or 12 mg/kg diazepam and 50 mg/kg phenobarbital) blocked the appearance of seizure and reduced almost completely the death caused by BAL. Carbamazepine (5 mg/kg) significantly reduced the incidence of BAL-induced seizures, while sodium valproate and MK-801 were not effective in reducing the incidence of seizures. Valproate (300 mg/kg) and MK-801(0.5 mg/kg) prolonged the latencies for onset of seizures; however, all animals died within one day after BAL administration. High doses of ZnCl₂ (135 mg/kg) blocked the appearance of seizures episodes, but no animal survived more than one day. The content of total non-protein—SH in brain of mice treated with 18.6 and 124 mg/kg BAL increased from 0.9 ± 0.3 nmol/g (control animals) to 1.7 ± 0.3 and 3.5 ± 0.8 nmol/g, respectively. In vitro, 0.1–1 mM concentrations of BAL inhibited [³H]glutamate and [³H]MK-801 binding, but increased the binding of [³H]muscimol to brain synaptic plasma membrane. The results reported here demonstrate that GABAergic allosteric modulators (diazepam and phenobarbital) and carbamazepine, a compound that acts by prolonging the recovery of voltage-activated ion channels from inactivation, are able to abolish BAL-induced seizures, while the NMDA antagonist (MK-801) prolonged the latencies for onset of seizures suggesting that modulators of this subtype of glutamate receptor have a modest role on BAL-induced seizures. The results of the present study suggest that allosteric modulators of GABAergic system and carbamazepine, a voltage-gated Na⁺-channel antagonist, should be considered for the treatment of animals or patients intoxicated with BAL.     

Maturation of Anthurium andraeanum cv. Eidibel somatic embryos from nodal segments

Maturation of somatic embryos of Anthurium andraeanum cv. Eidibel from embryogenic callus was evaluated. Following induction of embryogenic calli from nodal segments, tissues were transferred to 125-mL Erlenmeyer flasks containing 25 mL liquid medium, with 0, 4.52, or 9.05 μM 2,4-dichlorophenoxyacetic acid and 0, 0.47, or 2.32 μM kinetin. Callus cultures were maintained in a dark growth room at 25?±?2°C. At 45 d, the mass of embryogenic calli, number of primary and secondary somatic embryos, and percentage browning were evaluated. Nonparametric tests were used to evaluate color, texture, and somatic embryo development. The highest yield of somatic embryos was in the medium with 0.47 μM kinetin. Calli were friable, with a lower yield of secondary somatic embryos, and have minimal browning. Histology revealed polar globular somatic embryos and mature somatic embryos with defined apical and root meristematic zones, axillary buds, and primary leaves. These are important features for converting somatic embryos into plantlets.     

Diphenyl diselenide and diphenyl ditelluride differentially affect delta-aminolevulinate dehydratase from liver, kidney, and brain of mice

In the present study, the inhibitory effect of diphenyl diselenide and diphenyl ditelluride after in vitro, acute (a single dose), or chronic exposure (14 doses) was examined in mice 24 hours after the last administration. In vitro, diphenyl diselenide, and diphenyl ditelluride inhibited delta-aminolevulinate dehydratase (delta-ALA-D) from brain, liver, and kidney with a similar potency (IC50 5-10 microM), and at 120 microM, they increased the rate of dithiothreitol (DTT) and reduced glutathione (GSH) oxidation. After a single dose (sc), diphenyl diselenide (1 mmol/kg) inhibited the liver (22%, p < 0.01) and brain (27%, p < 0.01) delta-ALA-D, but it did not inhibit the kidney enzyme. After a single dose (sc), diphenyl ditelluride (0.5 mmol/kg) inhibited liver (46%, p < 0.01), kidney (21%, p < 0.05), and brain (39%, p < 0.01) delta-ALA-D. Chronic exposure to diphenyl diselenide (0.125 and 0.250 mmol/kg) caused significant (p < 0.05) increase in liver and liver-to-body weight ratio and inhibited liver (40 and 60%, respectively) and brain (21 and 40%, respectively) delta-ALA-D. Kidney delta-ALA-D was not inhibited significantly after exposure to diphenyl diselenide. Total nonprotein - SH concentration was decreased only in liver of animals exposed for 14 days to selenide. Chronic exposure to diphenyl ditelluride (0.010 and 0.025 mmol/kg) caused significant (p < 0.05) inhibition of liver (28 and 42%, respectively) and brain (23 and 54%, respectively) delta-ALA-D. Kidney delta-ALA-D was not inhibited significantly by diphenyl ditelluride. Total nonprotein--SH concentration was decreased to a different extent after acute or chronic treatment with diphenyl ditelluride depending on analyzed tissue. Hemoglobin content was decreased significantly by 17 and 22% after chronic treatment with 0.125 and 0.25 mmol/kg diphenyl diselenide, respectively. Chronic exposure to 0.010 mmol/kg diphenyl ditelluride caused a reduction of 17% in hemoglobin content that tended to be significant (p < 0.10). These results suggest that delta-ALA-D inhibition after exposure to organochalcogens may perturb heme-dependent metabolic pathway and contribute to the toxicological properties of these compounds.