Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus)
text Survival of teleost larvae requires growth and development which depend upon endocrine processes. In this dissertation I have examined the ontogeny of elements of the thyroid hormone (TH) and corticosteroid (CS) systems in red drum (Sciaenops ocellatus). Basal cortisol production was first dete...
Main Author: | |
---|---|
Other Authors: | |
Language: | English |
Published: |
2008
|
Subjects: | |
Online Access: | http://hdl.handle.net/2152/17730 |
id |
ftunivtexas:oai:repositories.lib.utexas.edu:2152/17730 |
---|---|
record_format |
openpolar |
spelling |
ftunivtexas:oai:repositories.lib.utexas.edu:2152/17730 2023-05-15T18:05:58+02:00 Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) Applebaum, Scott Lee, 1974- Nunez, B. Scott 2008-08 electronic application/pdf http://hdl.handle.net/2152/17730 eng eng http://hdl.handle.net/2152/17730 Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. Red drum--Larvae--Endocrinology Thyroid hormones--Receptors Glucocorticoids--Receptors Atrazine--Physiological effect Red drum--Larvae--Effect of stress on Stress (Physiology)--Endocrine aspects Messenger RNA 2008 ftunivtexas 2020-12-23T22:00:42Z text Survival of teleost larvae requires growth and development which depend upon endocrine processes. In this dissertation I have examined the ontogeny of elements of the thyroid hormone (TH) and corticosteroid (CS) systems in red drum (Sciaenops ocellatus). Basal cortisol production was first detected 3 days post-hatch (DPH) and a cortisol stress response was present from 6 DPH forward. Changes in steroidogenic enzyme mRNA (CYP11B and CYP21) levels did not correlate with these events. The time necessary to reach peak cortisol levels as well as return to basal levels declined as larvae developed. A second set of studies examined ontogenetic patterns in levels of mRNAs encoding thyroid (soTR[alpha] and soTR[beta]) and corticosteroid (soGR) hormone receptors and assessed the regulation of these mRNAs by exogenous triiodothyronine (T3) and cortisol. soTR[alpha], soTR[beta] and soGR were expressed in all stages of red drum examined. soTR[alpha] levels increased during the time when surging TH levels have been reported. soTR[beta] levels did not differ significantly during development. soGR levels were strongly correlated with those of soTR[alpha]. T3 up-regulated soTR[alpha] and soTR[beta] levels in 7 DPH, but not older larvae. Cross-regulation of receptor mRNAs by exogenous treatment with T3 or cortisol was not observed. Finally, I assessed the influence of a common herbicide, atrazine, on receptor mRNA, TH levels and growth of red drum. In two experiments, red drum exposed to environmentally relevant levels of atrazine did not alter hormone receptor mRNA levels, or TH content. However, atrazine did depress growth in some instances. In conclusion, the expression patterns of hormone receptor mRNA in embryos suggests receptor proteins could be activated by maternal hormones prior to the onset of endogenous hormone production. A correlation between soTR[alpha] and soGR mRNA levels suggests coordinated function of TH and CS systems, although regulatory interactions between these systems were not evident under the conditions in this study. Patterns in soTR[alpha] and soTR[beta] mRNA levels support an important role for TH in the larval to juvenile transformation of red drum larvae. The results also support growing evidence indicating atrazine exposure effects larval growth and may impact their survival in the wild. Marine Science Other/Unknown Material Red drum Sciaenops ocellatus The University of Texas at Austin: Texas ScholarWorks |
institution |
Open Polar |
collection |
The University of Texas at Austin: Texas ScholarWorks |
op_collection_id |
ftunivtexas |
language |
English |
topic |
Red drum--Larvae--Endocrinology Thyroid hormones--Receptors Glucocorticoids--Receptors Atrazine--Physiological effect Red drum--Larvae--Effect of stress on Stress (Physiology)--Endocrine aspects Messenger RNA |
spellingShingle |
Red drum--Larvae--Endocrinology Thyroid hormones--Receptors Glucocorticoids--Receptors Atrazine--Physiological effect Red drum--Larvae--Effect of stress on Stress (Physiology)--Endocrine aspects Messenger RNA Applebaum, Scott Lee, 1974- Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
topic_facet |
Red drum--Larvae--Endocrinology Thyroid hormones--Receptors Glucocorticoids--Receptors Atrazine--Physiological effect Red drum--Larvae--Effect of stress on Stress (Physiology)--Endocrine aspects Messenger RNA |
description |
text Survival of teleost larvae requires growth and development which depend upon endocrine processes. In this dissertation I have examined the ontogeny of elements of the thyroid hormone (TH) and corticosteroid (CS) systems in red drum (Sciaenops ocellatus). Basal cortisol production was first detected 3 days post-hatch (DPH) and a cortisol stress response was present from 6 DPH forward. Changes in steroidogenic enzyme mRNA (CYP11B and CYP21) levels did not correlate with these events. The time necessary to reach peak cortisol levels as well as return to basal levels declined as larvae developed. A second set of studies examined ontogenetic patterns in levels of mRNAs encoding thyroid (soTR[alpha] and soTR[beta]) and corticosteroid (soGR) hormone receptors and assessed the regulation of these mRNAs by exogenous triiodothyronine (T3) and cortisol. soTR[alpha], soTR[beta] and soGR were expressed in all stages of red drum examined. soTR[alpha] levels increased during the time when surging TH levels have been reported. soTR[beta] levels did not differ significantly during development. soGR levels were strongly correlated with those of soTR[alpha]. T3 up-regulated soTR[alpha] and soTR[beta] levels in 7 DPH, but not older larvae. Cross-regulation of receptor mRNAs by exogenous treatment with T3 or cortisol was not observed. Finally, I assessed the influence of a common herbicide, atrazine, on receptor mRNA, TH levels and growth of red drum. In two experiments, red drum exposed to environmentally relevant levels of atrazine did not alter hormone receptor mRNA levels, or TH content. However, atrazine did depress growth in some instances. In conclusion, the expression patterns of hormone receptor mRNA in embryos suggests receptor proteins could be activated by maternal hormones prior to the onset of endogenous hormone production. A correlation between soTR[alpha] and soGR mRNA levels suggests coordinated function of TH and CS systems, although regulatory interactions between these systems were not evident under the conditions in this study. Patterns in soTR[alpha] and soTR[beta] mRNA levels support an important role for TH in the larval to juvenile transformation of red drum larvae. The results also support growing evidence indicating atrazine exposure effects larval growth and may impact their survival in the wild. Marine Science |
author2 |
Nunez, B. Scott |
author |
Applebaum, Scott Lee, 1974- |
author_facet |
Applebaum, Scott Lee, 1974- |
author_sort |
Applebaum, Scott Lee, 1974- |
title |
Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
title_short |
Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
title_full |
Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
title_fullStr |
Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
title_full_unstemmed |
Regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (Sciaenops ocellatus) |
title_sort |
regulation of elements of the thyroid hormone and corticosteroid systems by stress, hormone treatment, and atrazine during ontogeny of red drum (sciaenops ocellatus) |
publishDate |
2008 |
url |
http://hdl.handle.net/2152/17730 |
genre |
Red drum Sciaenops ocellatus |
genre_facet |
Red drum Sciaenops ocellatus |
op_relation |
http://hdl.handle.net/2152/17730 |
op_rights |
Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
_version_ |
1766177521502519296 |