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.

Identification of serum proteome signature of irritable bowel syndrome: Potential utility of the tool for early diagnosis and patient's stratification.

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder with high incidence, and great heterogeneity of symptoms. Numerous factors are correlated with IBS development; however, the pathophysiology is not yet clear. In addition, there is no appropriate diagnostic tool available. The aim of this study was the identification of protein expression alterations in IBS patients compared to healthy individuals. Serum samples from 30 IBS patients (10 with IBS-Diarrhea, 10 IBS-Constipation and 10 IBS-Mixed) and 10 healthy individuals were subjected to proteomic analysis by 2-dimensional gel electrophoresis. Following evaluation of densitometrical data, protein spots exhibiting differential expression among the groups, were further characterized by matrix-assisted laser desorption tandem time-of-flight mass spectrometer and the results were confirmed by Western blot analysis. Eight significantly different expressed proteins were identified. Seven of them were overexpressed in IBS cases and only one was overexpressed in healthy individuals. These proteins were also differently expressed between the three IBS subgroups. IBS-D group overexpressed immunoglobulin light chain Lambda (LAC3) and apolipoprotein E (APOE), IBS-C group overexpressed apolipoprotein H (APOH) and collagen alpha-1 (XIV) chain (COEA1), and IBS-M group and healthy individuals overexpressed retinol-binding protein 4 (RET4). Our results show a different serum protein profile of IBS patients compared to healthy controls. Understanding the role of these eight proteins which are differently expressed in IBS patients, may contribute to a better clarification of IBS pathogenesis and to patient's stratification. SIGNIFICANCE: Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder with high incidence and great heterogeneity of symptoms without any appropriate diagnostic tool available. Eight significantly different expressed proteins were identified. Seven of them were overexpressed in IBS cases and only one was expressed in healthy individuals. These proteins were also differently expressed between the three IBS subgroups. Our results show that there is a different serum proteome signature in IBS compared to healthy individuals, as well as in IBS subgroups that could be used in the future for patient's stratification and as a diagnostic tool.