Cyanobacteria from terrestrial and marine sources contain apoptogens able to overcome chemoresistance in acute myeloid leukemia cells

Statistical Inferences Applying Non-Parametric Data on Cyanobacterial Investigations: Contributions to Water Quality and New Trends under Global Changes on Portuguese Freshwater Ecosystems

Cyanobacteria are a bloom-forming ancient group of photosynthetic prokaryotes. A rise in temperature is a major contributor to its massive proliferation, namely on freshwater ecosystems, with social and economic impacts. Thus, reliable and cost-effective tools can permit the fast surveillance and assessment of temperature effects on potentially toxic cyanobacteria distribution and impacts. The occurrence of three potentially toxic cyanobacteria species was assessed on seven sampling points across three sampling years. Moreover, the association between the occurrence of those cyanobacteria species with climate change events was addressed. Here, we combined molecular and statistical methods to study the impacts of temperature on the occurrence of three globally occurring cyanotoxin-producing cyanobacteria species—Microcystis aeruginosa (microcystins), Raphidiopsis raciborskii (cylindrospermopsins and saxitoxins) and Planktothrix agardhii (microcystins and saxitoxins). Samples were collected on seven European temperate freshwater systems located on the North and Centre regions of Portugal, across three distinct sampling years with distinct ranges of air temperature. Data support that M. aeruginosa is still a common inhabitant of Portuguese freshwater ecosystems and a new trend was found on R. raciborskii recent invasion and establishment on the colder north ecosystems of Portugal. Additionally, the highest frequency of detection of both cyanobacteria was associated with warmer years. P. agardhii also revealed a new trend, being reported for the first time on North and Centre Regions of Portugal, however with no statistical relation with air temperature, demonstrating a higher ecological fitness. Distinct profiles of the statistical analysis on the three tested cyanobacteria species contribute to deepen the studies on other species as well as of our analyzed species on a global level. This assessment may help to anticipate possible repercussions on water quality and public health due to most probable alterations on cyanotoxins profile given the ecological fitness established among air temperature and PCR detection of potentially toxic cyanobacteria.

Promising Activities of Marine Natural Products against Hematopoietic Malignancies

According to the WHO classification of tumors, more than 150 typologies of hematopoietic and lymphoid tumors exist, and most of them remain incurable diseases that require innovative approaches to improve therapeutic outcome and avoid side effects. Marine organisms represent a reservoir of novel bioactive metabolites, but they are still less studied compared to their terrestrial counterparts. This review is focused on marine natural products with anticancer activity against hematological tumors, highlighting recent advances and possible perspectives. Until now, there are five commercially available marine-derived compounds for the treatment of various hematopoietic cancers (e.g., leukemia and lymphoma), two molecules in clinical trials, and series of compounds and/or extracts from marine micro- and macroorganisms which have shown promising properties. In addition, the mechanisms of action of several active compounds and extracts are still unknown and require further study. The continuous upgrading of omics technologies has also allowed identifying enzymes with possible bioactivity (e.g., l-asparaginase is currently used for the treatment of leukemia) or the enzymes involved in the synthesis of bioactive secondary metabolites which can be the target of heterologous expression and genetic engineering.

Luciferase reporter assay for small-molecule inhibitors of MIR92b-3p function: Screening cyanopeptolins produced by Nostoc from the Baltic Sea

We developed a cell sensor that detects the liver cancer-specific microRNA MIR92b-3p, involved in hepatocellular carcinoma development and hepatitis C virus infection. To validate our small-molecule screen that employs a Huh7 human hepatoma cell line stably transfected with a pmirGLO vector containing dual luciferase reporters, we used i) a MIR92b-3p antisense or a MIR92b-3p mimicking agent (concentrations from 0.1 pM to 100 nM), ii) expression of XIST, a long non-coding RNA that is a cellular target of MIR92b, and iii) ectopic expression of Luc2 luciferase. This reporter system was used to test four cyanopeptolins from a de novo library of peptides that were isolated from the Baltic Sea cyanobacteria Nostoc edaphicum strain CCNP1411. Exposure of the Huh7-pmirGLO-MIR92b-3p cells to increasing concentrations (from 10 nM to 100 μM) of the cyanopeptolins and microcystin-LR (MC-LR; a treatment control) did not lead to a dose-dependent restoration of the luciferase signal. Instead, when the reporter cells were treated with MC-LR, the luciferase signal decreased markedly, most likely due to non-target, toxic effects of MC-LR on the cells. Although the first use of this reporter system to screen selected Nostoc peptides did not identify inhibitors of MIR92b, this method provides a means to identify functional miRNA regulators and could be readily extended to other compounds.

Dereplication of Natural Products with Antimicrobial and Anticancer Activity from Brazilian Cyanobacteria

Cyanobacteria are photosynthetic organisms that produce a large diversity of natural products with interesting bioactivities for biotechnological and pharmaceutical applications. Cyanobacterial extracts exhibit toxicity towards other microorganisms and cancer cells and, therefore, represent a source of potentially novel natural products for drug discovery. We tested 62 cyanobacterial strains isolated from various Brazilian biomes for antileukemic and antimicrobial activities. Extracts from 39 strains induced selective apoptosis in acute myeloid leukemia (AML) cancer cell lines. Five of these extracts also exhibited antifungal and antibacterial activities. Chemical and dereplication analyses revealed the production of nine known natural products. Natural products possibly responsible for the observed bioactivities and five unknown, chemically related chlorinated compounds present only in Brazilian cyanobacteria were illustrated in a molecular network. Our results provide new information on the vast biosynthetic potential of cyanobacteria isolated from Brazilian environments.

Diversity, Cyanotoxin Production, and Bioactivities of Cyanobacteria Isolated from Freshwaters of Greece

Cyanobacteria are a diverse group of photosynthetic Gram-negative bacteria that produce an array of secondary compounds with selective bioactivity against a broad spectrum of organisms and cell lines. In this study, 29 strains isolated from freshwaters in Greece were classified using a polyphasic approach and assigned to Chroococcales, Synechococcales, and Nostocales, representing 11 genera and 17 taxa. There were good agreements between 16S ribosomal RNA (rRNA)-cpcBA-internal genetic spacer (IGS) characterization and morphological features, except for the Jaaginema-Limnothrix group which appears intermixed and needs further elucidation. Methanol extracts of the strains were analyzed for cyanotoxin production and tested against pathogenic bacteria species and several cancer cell lines. We report for the first time a Nostoc oryzae strain isolated from rice fields capable of producing microcystins (MCs) and a Chlorogloeopsis fritschii strain isolated from the plankton of a lake, suggesting that this species may also occur in freshwater temperate habitats. Strains with very high or identical 16S rRNA gene sequences displayed different antibacterial and cytotoxic activities. Extracts from Synechococcus cf. nidulans showed the most potent antibacterial activity against Staphylococcus aureus, whereas Jaaginema sp. strains exhibited potent cytotoxic activities against human colorectal adenocarcinoma and hepatocellular carcinoma cells. Jaaginema Thessaloniki Aristotle University Microalgae and Cyanobacteria (TAU-MAC) 0110 and 0210 strains caused pronounced changes in the actin network and triggered the formation of numerous lipid droplets in hepatocellular carcinoma and green monkey kidney cells, suggesting oxidative stress and/or mitochondrial damage leading to apoptosis.

First use of the WAVE™ disposable rocking bioreactor for enhanced bioproduct synthesis by N2 -fixing cyanobacteria

WAVE™ rocking disposable bioreactors have been successfully utilized for bioproduct development from bacteria, yeast, microalgae, and animal and plant cells but not from cyanobacteria so far. N2 -fixing cyanobacteria represent a prolific bioproducts source with reduced cultivation costs. In this study, 1 L cultures of the N2 -fixing cyanobacterium Anabaena siamensis grown diazotrophically in the WAVE™ bioreactor exhibited increased phosphate consumption and 37-70% higher CO2 fixation rates than those grown in conventional bubbled suspension (BS) batch cultures. This generated 40-80% increased biomass productivities in the WAVE™ bioreactor reaching 60 mg L(-1)  day(-1) when supplemented with 10% CO2 . Consequently, WAVE™ generated 36-153% more protein, lipid, and carbohydrate than BS, including 47-100% increased productivity of phycocyanin and stearidonic acid (SA) with relevant biomedical applications. While the type of culture system (BS or WAVE(TM) ) did not affect the biochemical profile of cyanobacterial biomass, 10% CO2 supplementation induced a significant decrease in fatty acids and phycocyanin contents (mg g(-1)  DW). Therefore, for commercial applications, the CO2 supplementation of WAVE™ should be optimized for each targeted bioproduct separately. This study opens possibilities for upgrading the WAVE™ systems to photobioreactors (PBRs) for bioproduct development from cyanobacteria, with opportunities and challenges critically evaluated herein.