Background Thevetia peruviana (Pers.) K. Schum or Cascabela peruviana (L.) Lippold (commonly known as ayoyote, codo de fraile, lucky nut, or yellow oleander), native to Mexico and Central America, is a medicinal plant used traditionally to cure diseases like ulcers, scabies, hemorrhoids and dissolve tumors. The purpose of this study was to evaluate the cytotoxic, antiproliferative and apoptotic activity of methanolic extract of T. peruviana fruits on human cancer cell lines.MethodsThe cytotoxic activity of T. peruviana methanolic extract was carried out on human breast, colorectal, prostate and lung cancer cell lines and non-tumorigenic control cells (fibroblast and Vero), using the MTT assay. For proliferation and motility, clonogenic and wound-healing assays were performed. Morphological alterations were monitored by trypan blue exclusion, as well as DNA fragmentation and AO/EB double staining was performed to evaluate apoptosis. The extract was separated using flash chromatography, and the resulting fractions were evaluated on colorectal cancer cells for their cytotoxic activity. The active fractions were further analyzed through mass spectrometry.ResultsThe T. peruviana methanolic extract exhibited cytotoxic activity on four human cancer cell lines: prostate, breast, colorectal and lung, with values of IC50 1.91 ± 0.76, 5.78 ± 2.12, 6.30 ± 4.45 and 12.04 ± 3.43 μg/mL, respectively. The extract caused a significant reduction of cell motility and colony formation on all evaluated cancer cell lines. In addition, morphological examination displayed cell size reduction, membrane blebbing and detachment of cells, compared to non-treated cancer cell lines. The T. peruviana extract induced apoptotic cell death, which was confirmed by DNA fragmentation and AO/EB double staining. Fractions 4 and 5 showed the most effective cytotoxic activity and their MS analysis revealed the presence of the secondary metabolites: thevetiaflavone and cardiac glycosides.Conclusion T. peruviana extract has potential as natural anti-cancer product with critical effects in the proliferation, motility, and adhesion of human breast and colorectal cancer cells, and apoptosis induction in human prostate and lung cancer cell lines, with minimal effects on non-tumorigenic cell lines.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-017-1727-y) contains supplementary material, which is available to authorized users.

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The phylum Actinobacteria constitutes one of the largest and anciently divergent phyla within the Bacteria domain. Actinobacterial diversity has been thoroughly researched in various environments due to its unique biotechnological potential. Such studies have focused mostly on soil communities, but more recently marine and extreme environments have also been explored, finding rare taxa and demonstrating dispersal limitation and biogeographic patterns for Streptomyces. To test the distribution of Actinobacteria populations on a small scale, we chose the extremely oligotrophic and biodiverse Cuatro Cienegas Basin (CCB), an endangered oasis in the Chihuahuan desert to assess the diversity and uniqueness of Actinobacteria in the Churince System with a culture-dependent approach over a period of three years, using nine selective media. The 16S rDNA of putative Actinobacteria were sequenced using both bacteria universal and phylum-specific primer pairs. Phylogenetic reconstructions were performed to analyze OTUs clustering and taxonomic identification of the isolates in an evolutionary context, using validated type species of Streptomyces from previously phylogenies as a reference. Rarefaction analysis for total Actinobacteria and for Streptomyces isolates were performed to estimate species’ richness in the intermediate lagoon (IL) in the oligotrophic Churince system. A total of 350 morphologically and nutritionally diverse isolates were successfully cultured and characterized as members of the Phylum Actinobacteria. A total of 105 from the total isolates were successfully subcultured, processed for DNA extraction and 16S-rDNA sequenced. All strains belong to the order Actinomycetales, encompassing 11 genera of Actinobacteria; the genus Streptomyces was found to be the most abundant taxa in all the media tested throughout the 3-year sampling period. Phylogenetic analysis of our isolates and another 667 reference strains of the family Streptomycetaceae shows that our isolation effort produced 38 unique OTUs in six new monophyletic clades. This high biodiversity and uniqueness of Actinobacteria in an extreme oligotrophic environment, which has previously been reported for its diversity and endemicity, is a suggestive sign of microbial biogeography of Actinobacteria and it also represents an invaluable source of biological material for future ecological and bioprospecting studies.

BackgroundPseudomonas syringae pv. phaseolicola is a Gram-negative plant-pathogenic bacterium that causes "halo blight" disease of beans (Phaseolus vulgaris L.). This disease affects both foliage and pods, and is a major problem in temperate areas of the world. Although several bacterial genes have been determined as participants in pathogenesis, the overall process still remains poorly understood, mainly because the identity and function of many of the genes are largely unknown. In this work, a genomic library of P. syringae pv. phaseolicola NPS3121 was constructed and PCR amplification of individual fragments was carried out in order to print a DNA microarray. This microarray was used to identify genes that are differentially expressed when bean leaf extracts, pod extracts or apoplastic fluid were added to the growth medium.ResultsTranscription profiles show that 224 genes were differentially expressed, the majority under the effect of bean leaf extract and apoplastic fluid. Some of the induced genes were previously known to be involved in the first stages of the bacterial-plant interaction and virulence. These include genes encoding type III secretion system proteins and genes involved in cell-wall degradation, phaseolotoxin synthesis and aerobic metabolism. On the other hand, most repressed genes were found to be involved in the uptake and metabolism of iron.ConclusionThis study furthers the understanding of the mechanisms involved, responses and the metabolic adaptation that occurs during the interaction of P. syringae pv. phaseolicola with a susceptible host plant.

23Herein we describe the Archaea diversity in a shallow pond in the Cuatro Ciénegas Basin (CCB), 24Northeast Mexico, with fluctuating hypersaline conditions containing elastic microbial mats that 25 can form small domes where their anoxic inside reminds us of the characteristics of the Archaean 26Eon, rich in methane and sulfur gases; thus, we named this site the Archaean Domes (AD). These 27 domes only form after heavy rains that are rare in the Chihuahuan desert. CCB is a unique oasis 28 with hundreds of ponds, containing endemic species of animals, plants and highly diverse and 29 unique microbial communities, despite its very biased stoichiometry, due mostly to extreme low 30 phosphorus content (soils, water columns and sediments). This extreme oligotrophy has favored 31 survival of ancestral microorganisms. Whole metagenome sequencing approach was performed for 32 this unusual site in three different seasons to assess the extent of the Archaea biodiversity, with a 33 focus on extremophiles, since members of the Archaea had been underrepresented in different study 34 sites within the oasis. We found a highly diverse Archaea community compassing ~5% of the 35 metagenomes. The archaeal portion in all three metagenomes maintained its abundance and most of 36 the strains showed to form a resilient core during three seasonal samplings (2016-2017), despite 37 environmental fluctuations. However, relative abundances of all 230 archaeal OTUs (defined using 38 a 97% cutoff) were low enough (<0.1%) to be considered part of the rare biosphere. AD finding and 39 their description within CCB confirms that this particular pond is the most diverse for Archaea that 40we are aware of and opens new paths for understanding the forces that once drove and keep shaping 41 microbial community assemblage. 42 43 44 45 . CC-BY-NC-ND 4.0 International license is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/766709 doi: bioRxiv preprint Archaea domain remains largely unexplored [14] along with a diverse metabolism [15, 16], 64 unveiling new processes and key features involving microbes and community structure.65 Cuatro Cienegas Basin (CCB) is an endangered oasis within the northern zone of the 66 Chihuahuan Desert in Mexico, characterized by an extremely unbalanced nutrient stoichiometry of 67 the area (N:P = 159:1), similar to the conditions of the Precambrian sea [17-21]. Strikingly, despite 68 . CC-BY-NC-ND 4.0 International license is made available under aThe copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/766709 doi: bioRxiv preprint this nutrient deficiency CCB is considered a biodiversity hotspot for macroorganisms [22] and one 69 of the most diverse sites for microorganisms in the world [23][24][25][26][27]; this microbial biodiversity is 70 mirrored by its extreme diversity in virus [28]. CCB biodiversity is believed to have evolved as a 71result of a long time en...