Theses and Dissertations

Date of Award

12-1-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

MD Saydur Rahman

Second Advisor

Andrea Contina

Third Advisor

Ying Jia

Abstract

Beta-blockers are extensively used to treat human cardiovascular conditions yet pose significant risks to non-target aquatic organisms. This study aimed to investigate the effects of short-term exposure (one week) to a beta-blocker’s mixture (low-dose: 50 ng/L propranolol and 250 ng/L metoprolol, and high-dose: 250 ng/L propranolol and 650 ng/L metoprolol) in the American oysters. Histopathological assessments revealed structural damage to gills, connective tissues, and digestive glands in both low- and high-dose treatment groups. Additionally, glucose concentration and pH of the extrapallial fluid significantly declined in the high-dose treatment group. Hemocyte density within connective tissues increased proportionally with dosage. The beta-blocker mixture also reduces mucous secretion in tissues. Immunohistochemical results showed significant (P<0.05) upregulation of 3-nitrotyrosine protein expression in tissues. Alongside, exposure to beta-blockers significantly decreased acetylcholinesterase (AChE) expression in oyster tissues. Taken together our findings suggest that beta-blockers induce nitrative stress which alters tissue morphology, disrupts extrapallial fluid homeostasis, and downregulates AChE activity in tissues that may impair physiological functions in oysters.

Comments

Copyright 2024 Andrew Salinas. https://www.proquest.com/docview/3153382584

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