Study of Effects of Dopamine on Embryonic Cardiovascular Development in Zebrafish

Zebrafish share genetic similarities to human and have served as an effective animal model to study a wide range of biological processes in human. Dopamine is a neurotransmitter that plays a central role in brain functions. However, the role of dopamine in the development of cardiovascular system and heart function is less clear. In this study, we used a transgenic zebrafish with a cardiac protein (Flk1) fused with green fluorescence protein (GFP) that enables us to directly visualize the Flk1 cardiac protein, and developing cardiovascular system in developing zebrafish embryos, and studied the effects of their development in the presence of various concentrations of dopamine. We characterized the dependence of heart rates, hatching and phenotypes of developed zebrafish upon the concentration of dopamine in vivo in real time using optical and fluorescence microscopy. Our results show the high dependence of cardiovascular development and heart function of developing embryos upon the concentration of dopamine

Aging Study through Fin Regeneration in Zebrafish

Zebrafish (Danio rerio) are an emerging model for studying human aging. Zebrafish share similar senescence patterns and many homologous genes with humans. They also have extensive regeneration capacities, such as the ability to repair heart tissue and regrow entire fins. Their shared biological traits and the capacity for tissue regeneration lend promise to future biomedical research. Yet, as a novel model for gerontology, a better understanding of the relationship between Zebrafish age and the human age equivalent is needed. Zebrafish live a maximum of 66 months, but rarely make it to that age. Using the tMax formula, it may be estimated that one zebrafish year is approximately equivalent to 22 human years. This calculation is supported by anecdotal and observed evidence, however a more substantial correlation is needed. We have studied age-dependent regeneration capabilities of zebrafish by amputation of the caudal fin (tail fin) in different age groups of zebrafish and observation of the rate at which it fully regenerates. We aim to more firmly establish the major life stages of the Zebrafish and understand their unique regeneration capabilities. We will further our research to study the roles which blastema cells play in fin regeneration as well as to find genes and gene products responsible for the changes in regeneration rates and seek out human counterparts to these to design regenerative medicine

Host-defense piscidin peptides as antibiotic adjuvants against Clostridioides difficile.

The spore-forming intestinal pathogen Clostridioides difficile causes multidrug resistant infection with a high rate of recurrence after treatment. Piscidins 1 (p1) and 3 (p3), cationic host defense peptides with micromolar cytotoxicity against C. difficile, sensitize C. difficile to clinically relevant antibiotics tested at sublethal concentrations. Both peptides bind to Cu2+ using an amino terminal copper and nickel binding motif. Here, we investigate the two peptides in the apo and holo states as antibiotic adjuvants against an epidemic strain of C. difficile. We find that the presence of the peptides leads to lower doses of metronidazole, vancomycin, and fidaxomicin to kill C. difficile. The activity of metronidazole, which targets DNA, is enhanced by a factor of 32 when combined with p3, previously shown to bind and condense DNA. Conversely, the activity of vancomycin, which acts at bacterial cell walls, is enhanced 64-fold when combined with membrane-active p1-Cu2+. As shown through microscopy monitoring the permeabilization of membranes of C. difficile cells and vesicle mimics of their membranes, the adjuvant effect of p1 and p3 in the apo and holo states is consistent with a mechanism of action where the peptides enable greater antibiotic penetration through the cell membrane to increase their bioavailability. The variations in effects obtained with the different forms of the peptides reveal that while all piscidins generally sensitize C. difficile to antibiotics, co-treatments can be optimized in accordance with the underlying mechanism of action of the peptides and antibiotics. Overall, this study highlights the potential of antimicrobial peptides as antibiotic adjuvants to increase the lethality of currently approved antibiotic dosages, reducing the risk of incomplete treatments and ensuing drug resistance