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Brevetoxin Metabolism and Physiology - A Freshwater Model of Morbidity in Endangered Sea Turtles
Title
Brevetoxin Metabolism and Physiology - A Freshwater Model of Morbidity in Endangered Sea Turtles.
Creator
Cocilova, Courtney Christine, Milton, Sarah L., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
The dinoflagellate Karenia brevis is one organism responsible for harmful algal blooms (HABs) that severely impact marine life. K. brevis produces a suite of neurotoxins referred to as brevetoxins (PbTx) which bind to voltage-gated sodium channels (VGSCs) in excitable tissues, affecting cellular permeability leading to a suite of symptoms and potentially cell death. Brevetoxicosis is difficult to treat in sea turtles as the physiological impacts have not been investigated and the magnitude...
Show moreThe dinoflagellate Karenia brevis is one organism responsible for harmful algal blooms (HABs) that severely impact marine life. K. brevis produces a suite of neurotoxins referred to as brevetoxins (PbTx) which bind to voltage-gated sodium channels (VGSCs) in excitable tissues, affecting cellular permeability leading to a suite of symptoms and potentially cell death. Brevetoxicosis is difficult to treat in sea turtles as the physiological impacts have not been investigated and the magnitude and duration of brevetoxin exposure are generally unknown. Due to their threatened and endangered status, experimental exposures cannot be performed to determine the fate of brevetoxin in sea turtle tissues, making it difficult to design appropriate treatments. The freshwater turtle, Trachemys scripta, was utilized as a model for brevetoxin exposure in turtles. Turtles were exposed to intratracheal instillation (10.53μg/kg) or oral dosing (33.48μg/kg) of PbTx-3 3x weekly over a period of 2-4 weeks. Tissues and fluids were collected for ELISA to determine PbTx-3 uptake and distribution, routes of excretion and rates of clearance (1h-1wk post-exposure). Tissues were also preserved for histopathology. Primary turtle neuronal cell cultures were exposed to PbTx-3 in the presence and absence of various agonists and antagonists to determine brevetoxin’s mode of action. PbTx-3 was widely distributed in all tissues and fluids following both intratracheal and oral exposures, but was largely cleared from the system within 24 hours; PbTx-3 moved into the bile and feces over 48h post exposure indicating that this is the main route of excretion. While exposed animals showed clear behavioral symptoms of toxicity including muscle twitching, swimming in circles, and ataxia, there was no evident tissue pathology. Despite the evident behavioral effects, turtle neurons are surprisingly resistant to PbTx-3, with an EC50 significantly higher than is seen in mammalian neurons. While PbTx-3 exposure resulted in significant Ca2+ influx, various antagonists prevented Ca2+ influx when added with PbTx-3 confirming the mechanism of action through VGSCs. Upregulation of Hsp72 in the turtle brain could be enhancing cell survival. Based on results, intralipid treatment post PbTx-3 exposure rapidly decreases symptoms and proves to be a suitable treatment for toxin exposure.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004812
Subject Headings
Sea turtles--Mortality., Sea turtles--Physiology., Marine toxins., Neurotoxic agents--Analysis.
Format
Document (PDF)
Developmental Morphology of Flippers in Sea Turtles and Penguins
Title
Developmental Morphology of Flippers in Sea Turtles and Penguins.
Creator
Kwong, Grace W., Wyneken, Jeanette, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
There are no modem anatomical studies of flipper development or particularly any examining limb formation across distantly related taxa converging on similar flipper morphology. This study compares and contrasts the development of flippers in sea turtle (Caretta caretta) and penguin (Spheniscus demersus , Eudyptula minor) embryos. Embryos were fixed, cleared and stained for cartilage anlagen, and prepared as whole mounts. Skeletal elements forming the flipper and changes in their growth rates...
Show moreThere are no modem anatomical studies of flipper development or particularly any examining limb formation across distantly related taxa converging on similar flipper morphology. This study compares and contrasts the development of flippers in sea turtle (Caretta caretta) and penguin (Spheniscus demersus , Eudyptula minor) embryos. Embryos were fixed, cleared and stained for cartilage anlagen, and prepared as whole mounts. Skeletal elements forming the flipper and changes in their growth rates were described across developmental stages. Results suggest skeletal elements contribute differently to sea turtle and penguin flipper blades and there are significant differences in bone shape and growth patterns. Greater proportional increases in lengths and areas were found in sea turtles elements compared to penguins. Sea turtles appear to depend on a pathway resulting in elongation of distal elements to build a flipper, whereas penguin limbs undergo flattening and expansion of fewer elements to meet a similar structural goal.
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Date Issued
2006
PURL
http://purl.flvc.org/fau/fd/FA00000784
Subject Headings
Sea turtles--Physiology, Sea turtles--Morphology, Penguins--Morphology, Animal locomotion, Marine ecology
Format
Document (PDF)