Journal of the South Carolina Academy of Science最新文献

Infectious diseases caused by drug-resistant microorganisms have become a major contributor for human morbidity and mortality. To overcome such threats, we have developed various antimicrobial agents using natural product derivatives and metallopolymers. Abundant biomass such as resin acids can be utilized to prepare cationic polymers for inhibiting a variety of bacteria. These polymers have been used in solution as well as surfaces as antimicrobial materials with low cytotoxicity. In addition, a class of charged metallopolymers have been developed to kill superbugs such as MRSA.

Zebrafish are a highly-valued model organism used for developmental biology research. Zebrafish can be used for genetic manipulation and hence, many mutant and transgenic lines exist. It is impractical to maintain lines of adult zebrafish, due to resource constraints and the need to continuously produce new generations. Therefore, a practical way to preserve zebrafish lines is to freeze sperm and retrieve lines using in vitro fertilization of fresh eggs. Most existing in vitro protocols used by research labs have a wide variety of fertilization rates (ranging from 0% to >90%). Due to this variability, lines may be at risk of not being regenerated, and may be permanently lost. For this project, aspects of existing published sperm collection protocols were tested and modified, with the goal of improving the proportion of males giving quality ejaculate. Males were tested for production of ejaculate by housing fish either in groups or in separate, individual tanks the night before sperm collection. The effect of age of male zebrafish and genetic background (5D and AB lines) on production of quality ejaculate was also tested. Isolating males before sperm collection significantly increased the proportion of individuals producing quality ejaculate. The proportion of fish that gave quality ejaculate samples did not co-vary with age between 17-68 weeks. Overall, AB fish were significantly more likely to give quality ejaculate samples compared to 5D fish. Based on this study, we strongly recommend separating male fish before sperm collection to improve the likelihood of obtaining samples. Our results indicate that AB fish give proportionately better samples than 5D fish, and this does not vary with age between 17-68 weeks.

Despite the significant impacts on human health caused by neurodegeneration, our understanding of the degeneration process is incomplete. The nematode Caenorhabditis elegans is emerging as a genetic model organism well suited for identification of conserved cellular mechanisms and molecular pathways of neurodegeneration. Studies in the worm have identified factors that contribute to neurodegeneration, including excitotoxicity and stress due to reactive oxygen species (ROS). Disruption of the gene unc-68, which encodes the ryanodine receptor, abolishes excitotoxic cell death, indicating a role for calcium (Ca²⁺) signaling in neurodegeneration. We tested the requirement for unc-68 in ROS-mediated neurodegeneration using the genetically encoded photosensitizer KillerRed. Upon illumination of KillerRed expressing animals to produce ROS, we observed similar levels of degeneration in wild-type and unc-68 mutant strains. Our results indicate that ROS-mediated cell death is independent of unc-68 and suggest multiple molecular pathways of neurodegeneration.