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Alternative Title

Exploring the connection between connexin dependent bioelectrics and morphogen signaling during axis determination in zebrafish

Publication Date


First Advisor

Michael J.F. Barresi

Document Type

Honors Project

Degree Name

Bachelor of Arts


Biological Sciences


Zebrafish, Bioelectrics, Gap junctions, Connexins, Morphogens, Fgf, Axis determination


Axis determination is a fundamental process that occurs during embryonic development. Differential specification of cell fates across the blastula and gastrula determine where the head, tail, back, and belly will develop. It is readily understood that gradients of biochemical morphogens play a critical signaling role that specify and pattern cell fates during axis determination in the early vertebrate embryo. Such morphogens include members of the Bone Morphogenic Protein (BMP), Fibroblast Growth Factor (FGF), and Nodal families. Their genes are known to be expressed in distinct patterns along the dorsoventral axis in developing zebrafish embryos. Recent evidence suggests that inductive effects of such morphogens may themselves be regulated by different states of membrane potential across tissues. However, no studies to date have examined whether bioelectric signaling regulates the expression and or functions of morphogens in gastrulating embryos. Preliminary studies from our lab suggest that distinct bioelectric patterns may exist prior to the determination of cell fates along the zebrafish axes. To dissect whether bioelectrics may play a superimposing role on the inductive effects of morphogens, we set out to test whether Connexin-mediate bioelectric signaling is essential for early axis determination and whether it operates through FGF signaling. Using a variety of genetic and pharmacological tools to manipulate both connexin and FGF signaling, we show that connexin-mediate bioelectrics is required for proper anterior brain and posterior tail development. Furthermore, we show that proper Fgf8 expression is dependent upon connexin signaling. Our preliminary findings suggest that connexin-dependent bioelectric signaling may regulate FGF expression patterns that have profound impacts on axis determination in zebrafish. Here we propose to take advantage of the high resolution microscopy, and genetic tools of the zebrafish model system to characterize the role that gap junctions play in the differential bioelectric patterns present in the early embryo as well as characterize the nature of bioelectric-mediated morphogenic regulation.


©2021 Janeth Mora-Martinez. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.




45 pages : color illustrations. Includes bibliographical references (pages 42-45)