Biology ETDs

Publication Date

Fall 11-10-2020

Abstract

Conquering land was an apex moment in the evolution of vertebrates. Physiologically, the first vertebrates to transition to life on land had to adapt in order to survive in an oxygen-rich environment where gravitational forces and limited water prevailed. Several extant vertebrates including anurans and lungfish, survive droughts by undergoing aestivation. Unfavorable environmental conditions trigger lungfish to aestivate. Aestivation is a process of metabolic torpor wherein the fish will encase itself in a mucus cocoon and not move until favorable environmental conditions (food and water) are reintroduced. Aestivation can be reproduced in laboratory settings and, thus, lungfish can be used as a model to investigate the transition from aquatic to terrestrial life. Once in their cocoon, lungfish are immobile and therefore cannot escape pathogens present in the external environment. Moreover, metabolic torpor means limited energy to fight infection. Clearly, aestivation poses a challenge to the vertebrate immune system as we know it and lungfish must have evolved unique solutions to overcome such challenges. The goal of this dissertation is to characterize the unique innovations of the mucosal immune system of lungfish in water and land. The findings presented here reveal drastic adaptations in the immune system of free-swimming lungfish that serve them during the aestivating phase. Additionally, the lungfish cocoon appears as an outer body living tissue that traps bacteria during life on land. Combined, this body of work reveals previously unknown mechanisms by which vertebrates overcome the problem of fighting pathogens during metabolic torpor.

Keywords

Aestivation, Mucosal Immunity, Lungfish

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

Irene Salinas

Second Committee Member

Eric Y. Denkers

Third Committee Member

Christopher A. Johnston

Fourth Committee Member

Chris T. Amemiya

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