Graduation Year

2021

Graduation Month

May

Document Type

Thesis

Degree Name

Bachelor of Science

School or Department

Biological Sciences, Division of

Major

Biology – Human Biological Sciences

Faculty Mentor

Zachary A. Cheviron

Faculty Mentor Department

Biological Sciences, Division of

Keywords

Hypoxia, plasticity, placenta, high-elevation

Subject Categories

Other Ecology and Evolutionary Biology

Abstract

High altitude residence causes fetal growth restriction (FGR) during pregnancy in lowland mammals. Highland-adapted mammals do not experience this altitude-dependent FGR, suggesting that adaptation to altitude has produced some protective mechanisms. However, the specific mechanisms by which highland-adapted mammals preserve fetal growth at altitude remain unknown. We hypothesized that highland-adapted populations protect fetal growth through structural changes to the placenta that increase surface area for nutrient and gas exchange. We tested this hypothesis using deer mice (Peromyscus maniculatus), from populations native to low [400 m, Lincoln, NE] and high [4300 m, Mt. Evans, CO] altitudes. We predicted structural adaptation would occur via increases to the relative size of the labyrinth zone (LZ), the layer within the rodent placenta where nutrient and gas exchange occur. Placentas were collected from lowland and highland deer mice undergoing pregnancy under normoxia or hypoxia (60 kPa) to understand how hypoxia-dependent structural plasticity might interact with adaptive remodeling of the placenta (N = 5-7 per strain and treatment). Using immunohistochemistry, we quantified the size of each placenta zone. Our preliminary results show that highlanders have relatively larger placental arteries and LZs under both normoxia and hypoxia (P < 0.05 in generalized linear mixed model), suggesting that blood delivery and area for exchange (as determined by the LZ size) may protect fetal growth in highlanders. Future work will pair histological characterization of placental structure with transcriptomics to guide a mechanistic understanding of how placentation constrains to fetal growth under hypoxia.

Honors College Research Project

Yes

GLI Capstone Project

no

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© Copyright 2021 Hannah C. Johnson, Kathryn Wilsterman, Jeffrey M. Good, and Zachary A. Cheviron