Antimutagenicity and antigenotoxicity of Aloe arborescens Miller and Aloe barbadensis Miller in Aspergillus nidulans and Wistar rats

Medicinal plants such as Aloe arborescens Miller and Aloe barbadensis Miller are used by the general population to treat various diseases. Therefore, the aim of this study was to evaluate the antimutagenicity of these two species using a methG1 system in Aspergillus nidulans and the comet assay in rats. The animals were treated with the plants at concentrations of 360 and 720 mg/kg body weight (1 and 2, respectively) by gavage for 14 days, followed by the administration of etoposide on treatment day 8. Blood samples were prepared for analysis of DNA damage. For the test in A. nidulans, the biA1methG1 lineage conidia were treated for 4 h with both plant species at concentrations of 4 and 8% (w/v). Then, they were washed and plated on a selective medium for frequency analysis of survival and mutation. The results of the comet assay showed that both plants were antigenotoxic compared to etoposide, which was not a typical response of methG1 systems, where only the highest concentration of plant extracts usually exhibit beneficial effects. This study demonstrates the potential antigenotoxicity and antimutagenicity of the Aloe plants tested and, therefore, supports their use as a form of preventive therapy and for health maintenance by the population.

In situ analysis of apoptosis in Aspergillus nidulans with ethidium bromide and acridine orange

Apoptosis and necrosis are among several types of cell death. We stained the nuclei of Aspergillus nidulans grown in micro-colonies with ethidium bromide and acridine orange to detect in situ apoptosis. Suspensions of conidia from 5-day-old colonies of the A. nidulans strains biA1methG1, G422, CLC100, and CLB3 were each put into two tubes. The suspension of one tube was irradiated with ultraviolet light for 20 s, whereas the other tube was not exposed to irradiation. The two suspensions were inoculated in complete liquid medium and 50-µL samples were placed on sterilized cover slips, spread on the surface of solid culture media on Petri dishes. After the micro-colonies were formed, the material on the cover slips was stained with ethidium bromide and acridine orange, placed on the lamina and observed under a fluorescence microscope. This staining method was efficient in discriminating normal nuclei from those going apoptosis and necrosis. Results have shown that irradiation provokes apoptosis but does not induce necrosis. There were no differences between the three strains and all data were considered to be statistically significant.

Genome of Herbaspirillum seropedicae strain SmR1, a specialized diazotrophic endophyte of tropical grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme--GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species.