Regeneration following tissue damage often necessitates a mechanism for cellular reprogramming , so that surviving cells can give rise to all cell types originally found in the damaged tissue. This process, if unchecked, can also generate cell types that are inappropriate for a given location. We conducted a screen for genes that negatively regulate the frequency of notum-towing transformations following genetic ablation and regeneration of the wing pouch, from which we identified mutations in the transcriptional co-repressor C-terminal Binding Protein (CtBP). When CtBP function is reduced, ablation of the pouch can activate the JNK/AP-1 and JAK/STAT pathways in the notum to destabilize cell fates. Ectopic expression of Wingless and Dilp8 precede the formation of the ectopic pouch, which is subsequently generated by recruitment of both anterior and posterior cells near the compartment boundary. Thus, CtBP stabilizes cell fates following damage by opposing the destabilizing effects of the JNK/AP-1 and JAK/STAT pathways.

The gastrointestinal epithelial layer forms a physical and biochemical barrier that maintains the segregation between host and intestinal microbiota. The integrity of this barrier is critical in maintaining homeostasis in the body and its dysfunction is linked to a variety of illnesses, especially inflammatory bowel disease. Gut microbes, and particularly probiotic bacteria, modulate the barrier integrity by reducing gut permeability and reinforcing tight junctions. Probiotic Escherichia coli Nissle 1917 (EcN) is a good colonizer of the human gut with proven therapeutic efficacy in the remission of ulcerative colitis in humans. EcN positively modulates the intestinal epithelial barrier through upregulation and redistribution of the tight junction proteins ZO-1, ZO-2 and claudin-14. Upregulation of claudin-14 has been attributed to the secreted protein TcpC. Whether regulation of ZO-1 and ZO-2 is mediated by EcN secreted factors remains unknown. The aim of this study was to explore whether outer membrane vesicles (OMVs) released by EcN strengthen the epithelial barrier. This study includes other E. coli strains of human intestinal origin that contain the tcpC gene, such as ECOR63. Cell-free supernatants collected from the wild-type strains and from the derived tcpC mutants were fractionated into isolated OMVs and soluble secreted factors. The impact of these extracellular fractions on the epithelial barrier was evaluated by measuring transepithelial resistance and expression of several tight junction proteins in T-84 and Caco-2 polarized monolayers. Our results show that the strengthening activity of EcN and ECOR63 does not exclusively depend on TcpC. Both OMVs and soluble factors secreted by these strains promote upregulation of ZO-1 and claudin-14, and down-regulation of claudin-2. The OMVs-mediated effects are TcpC-independent. Soluble secreted TcpC contributes to the upregulation of ZO-1 and claudin-14, but this protein has no effect on the transcriptional regulation of claudin-2. Thus, in addition to OMVs and TcpC, other active factors released by these microbiota strains contribute to the reinforcement of the epithelial barrier.

Among the palette of previously described fluorescent organic molecules, coumarins are ideal candidates for developing cellular and molecular imaging tools due to their high cell permeability and minimal perturbation of living systems. However, blue-to-cyan fluorescence emission is usually difficult in in vivo applications due to the inherent toxicity and poor tissue penetration of short visible light wavelengths. Here, we introduce a new family of coumarin-based fluorophores, nicknamed COUPY, with promising photophysical properties, including emission in the far-red/near-infrared (NIR) region, large Stokes shifts, high photostability, and excellent brightness. COUPY fluorophores were efficiently synthesized in only three linear synthetic steps from commercially available precursors, with the N-alkylation of a pyridine moiety being the key step at the end of the synthetic route, as it allows for the tuning of the photophysical properties of the resulting dye. Owing to their low molecular weights, COUPY dyes show excellent cell permeability and accumulate selectively in nucleoli and/or mitochondria of HeLa cells, as their far-red/NIR fluorescence emission is easily detected at a concentration as low as 0.5 μM after an incubation of only 20 min. We anticipate that these coumarin scaffolds will open a way to the development of novel coumarin-based far-red to NIR emitting fluorophores with potential applications for organelle imaging and biomolecule labeling.

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BackgroundRegeneration is the ability of an organism to rebuild a body part that has been damaged or amputated, and can be studied at the molecular level using model organisms. Drosophila imaginal discs, which are the larval primordia of adult cuticular structures, are capable of undergoing regenerative growth after transplantation and in vivo culture into the adult abdomen.ResultsUsing expression profile analyses, we studied the regenerative behaviour of wing discs at 0, 24 and 72 hours after fragmentation and implantation into adult females. Based on expression level, we generated a catalogue of genes with putative role in wing disc regeneration, identifying four classes: 1) genes with differential expression within the first 24 hours; 2) genes with differential expression between 24 and 72 hours; 3) genes that changed significantly in expression levels between the two time periods; 4) genes with a sustained increase or decrease in their expression levels throughout regeneration. Among these genes, we identified members of the JNK and Notch signalling pathways and chromatin regulators. Through computational analysis, we recognized putative binding sites for transcription factors downstream of these pathways that are conserved in multiple Drosophilids, indicating a potential relationship between members of the different gene classes. Experimental data from genetic mutants provide evidence of a requirement of selected genes in wing disc regeneration.ConclusionsWe have been able to distinguish various classes of genes involved in early and late steps of the regeneration process. Our data suggests the integration of signalling pathways in the promoters of regulated genes.

Photodynamic therapy (PDT) for cancer treatment has drawn increased attention over the last decades. Herein, we introduce a novel family of low-molecular-weight coumarins as potential PDT anticancer tools. Through a systematic study with a library of 15 compounds, we have established a detailed structure–activity relationship rationale, which allowed the selection of three lead compounds exhibiting effective in vitro anticancer activities upon visible-light irradiation in both normoxia and hypoxia (phototherapeutic indexes up to 71) and minimal toxicity toward normal cells. Acting as excellent theranostic agents targeting mitochondria, the mechanism of action of the photosensitizers has been investigated in detail in HeLa cells. The generation of cytotoxic reactive oxygen species, which has been found to be a major contributor of the coumarins’ phototoxicity, and the induction of apoptosis and/or autophagy have been identified as the cell death modes triggered after irradiation with low doses of visible light.

The lack of correlation between BIC and ISQ values suggests that ISQ as determined by RFA is not able to identify the relationship between RF and histomorphometrical data.

Symbiotic interactions between ascidians (sea-squirts) and microbes are poorly understood. Here we characterized the cyanobacteria in the tissues of 8 distinct didemnid taxa from shallow-water marine habitats in the Bahamas Islands by sequencing a fragment of the cyanobacterial 16S rRNA gene and the entire 16S–23S rRNA internal transcribed spacer region (ITS) and by examining symbiont morphology with transmission electron (TEM) and confocal microscopy (CM). As described previously for other species, Trididemnum spp. mostly contained symbionts associated with the Prochloron-Synechocystis group. However, sequence analysis of the symbionts in Lissoclinum revealed two unique clades. The first contained a novel cyanobacterial clade, while the second clade was closely associated with Acaryochloris marina. CM revealed the presence of chlorophyll d (chl d) and phycobiliproteins (PBPs) within these symbiont cells, as is characteristic of Acaryochloris species. The presence of symbionts was also observed by TEM inside the tunic of both the adult and larvae of L. fragile, indicating vertical transmission to progeny. Based on molecular phylogenetic and microscopic analyses, Candidatus Acaryochloris bahamiensis nov. sp. is proposed for this symbiotic cyanobacterium. Our results support the hypothesis that photosymbiont communities in ascidians are structured by host phylogeny, but in some cases, also by sampling location.