Science

Role of the ZO-1 ZU5 Domain in Regulating Cingulin Organization at Epithelial Tight Junctions 

Joauna Carter
Trinity University

Epithelial tissues rely on tight junctions to maintain barrier function. The scaffolding protein ZO-1 recruits cingulin through its ZU5 domain, but the specific amino acids responsible for this interaction remain unknown. We hypothesized that mutations within the ZO-1 ZU5 hydrophobic pocket would alter cingulin recruitment to epithelial tight junctions. Madin-Darby Canine Kidney epithelial cells expressing enhanced green fluorescent protein-tagged ZO-1 rescue constructs were immunostained for cingulin and imaged by confocal microscopy. A full-length ZO-1 rescue construct and a triple hydrophobic-pocket mutant were compared using fluorescence line-scan analysis to quantify cingulin localization. Full-length ZO-1 rescue cells exhibited higher corrected peak cingulin fluorescence at enhanced green fluorescent protein-positive junctions, consistent with more efficient recruitment or stabilization of cingulin at tight junctions. In contrast, induction of the triple hydrophobic-pocket mutant did not produce a similar increase in cingulin fluorescence, suggesting that these residues contribute to efficient cingulin recruitment. These findings establish a quantitative approach for evaluating cingulin localization and provide a foundation for identifying the amino acid residues within the ZO-1 ZU5 domain that regulate the ZO-1–cingulin interaction and epithelial tight junction organization.

Investigating The Influence of Entomoplasma Mollicutes on Winter Firefly Health

Edyn Saavedra
University of Texas at Arlington

Gut microbes can play key roles in host health. Mollicutes is a class of diverse bacteria that vary in symbiotic relationships, ranging from beneficial to parasitic in plants, marine life, and insects. The mollicute Entomoplasma corruscae is species-specific to the Winter Firefly Photinus corruscus and putatively functions as a beneficial symbiont. With fireflies holding cultural significance, inferring the effects of symbionts in fireflies can improve our understanding of firefly survivability in the wild. We hypothesized that E. corruscae plays a beneficial role in Winter Firefly health and predict that fireflies harboring a high abundance of these mollicutes will (1) survive longer, and (2) gain more weight over time. In this experiment we separated nearly 200 fireflies into three groups and exposed them to different dietary treatments: antibiotics, mollicute isolates, and control. An E. corruscae strain was grown in the lab and used in the mollicute treatment. After two months of treatment, our quantitative PCR results indicate that the abundance of mollicutes was drastically reduced through antibiotic ingestion, but remained high in fireflies exposed to a mollicute or control diet. Yet, firefly survival and weight did not differ across treatments. In conclusion, E. corruscae may not directly be involved in host survival and may derive greater benefits from the host than it provides in return. Further studies are needed to understand the function of E. corruscae and its relationship with Winter Fireflies, especially in more challenging conditions.

Emilio Gutierrez