Award Date

August 2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Committee Member

Allyson Hindle

Second Committee Member

Sean Neiswenter

Third Committee Member

Mo Weng

Fourth Committee Member

Gary Kleiger

Number of Pages

153

Abstract

Increasing temperatures with the potential for heat stress is among the future threats facing many mammals. Cellular mechanisms to maintain homeostasis in the face of heat stress likely differ across species based on naturally tolerated intracellular variability. In some mammals, the homeostatic set point in cells has a narrow range. Other species tolerate more varied intracellular conditions, including in temperature. Heat stress responses of cultured dermal fibroblasts from several mammals were compared to detect cell proliferation and cellular death (chapter 2). Cells from heat- tolerant species (13-lined ground squirrel, dromedary camel, round-tailed ground squirrel, and white-tailed antelope squirrel) were compared with cells from species with narrow observed body temperature ranges (human, rat, and southern white rhinoceros) to determine whether cell stress responses were consistent with known physiological flexibility. Consistent with predictions from organismal phenotypes, fibroblasts of presumed heat tolerant mammals were able to maintain cell proliferation at 41°C over many days compared to fibroblasts from heat sensitive mammals. Organismal phenotypes were not, however, consistent with cellular death levels. The mechanisms in response to heat stress were investigated to detect protein abundance and heat- stress gene expression patterns (HSF1, ERN1, PRKAA2, and CDKN1A) underlying resilience to heat stress versus patterns reflecting sensitivity (chapter 3). Immediate induction of ERN1 in the dromedary camels were identified. This study also identified patterns in HSF1 expression in rats, ERN1 expression in the southern white rhinoceros, PRKAA2 expression in the round-tailed ground squirrels, southern white rhinoceros and rat, and CDKN1A expression in the southern white rhinoceros over shorter scaled time durations of heat exposure at 41°C. Cells from rat, antelope ground squirrel, and 13- lined ground squirrel were analyzed via proteomics following a 6- and 24h heat exposure. Differentially expressed proteins provided better insight into species-specific response mechanisms to heat stress.

Controlled Subject

Mammals; Cellular control mechanisms; Homeostasis; Deserts

Disciplines

Biology

File Format

pdf

File Size

3930 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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