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Environmentally Sensitive Transcription Factors in the Prolactin Cell, Gill and Kidney of Mozambique Tilapia (Oreochromis mossambicus).

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Environmentally Sensitive Transcription Factors in the Prolactin Cell, Gill and Kidney of Mozambique Tilapia (Oreochromis mossambicus)./
Author:	Tharindu Malintha, Gardi Hewage.
Description:	1 online resource (155 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Animal sciences. -
Online resource:	click for full text (PQDT)
ISBN:	9798380405478

Environmentally Sensitive Transcription Factors in the Prolactin Cell, Gill and Kidney of Mozambique Tilapia (Oreochromis mossambicus).
Tharindu Malintha, Gardi Hewage.

Environmentally Sensitive Transcription Factors in the Prolactin Cell, Gill and Kidney of Mozambique Tilapia (Oreochromis mossambicus). - 1 online resource (155 pages)

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--University of Hawai'i at Manoa, 2023.

Includes bibliographical references

In this thesis, I investigated the molecular mechanisms underlying the transduction of two fundamental sensory modalities, osmoreception and thermosensitivity, in fish. The scope and depth of this investigation was facilitated by employing a tractable study model of high physiological relevance in changing environments, the euryhaline Mozambique tilapia, Oreochromis mossambicus. The pituitary hormone prolactin (Prl) plays a fundamental role during acclimation to fresh water (FW) in euryhaline fishes by promoting ion uptake and retention in osmoregulatory epithelia. Consistent with this role, tilapia Prl cells are sensitive to variations in extracellular osmolality, responding by increasing cell volume and intracellular Ca2+ concentration when osmolality falls. I characterized the activation of transcription factor modules (TFM) from Prl cells following osmotic stimulation and found that their responses were also dependent on the acclimation history of the fish. TFM's such as pituitary transcription factor 1 (Pit1), were strongly activated by hyposmotic stimuli, while others, such as HMG box-containing protein 1 (SORY_PAX3), a known transcriptional repressor, was activated in response to hyperosmotic stimuli, indicating the presence of molecular mechanisms that both enhance and attenuate prl177 and prl188 transcription in response to osmotic stimuli.Following the recent discovery that a rise in temperature also stimulates Prl release, I tested the involvement of osmosensitve TFMs in Prl cells incubated in temperatures ranging from 20 ℃ to 32 ℃ and found that low temperature inhibits the response of Prl cells to hyposmotic media. Interstingly, TFM transcripts that typically increase with a hyposmotic stimulus were generally downregulated with a rise in temperature. Last, gill and kidney are two of the main osmoregulatory tissues in fish, and targets of Prl's actions during salinity acclimation. I employed a comparative RNA-seq approach to characterize transcriptional responses of branchial and renal gene networks involved in FW- and seawater (SW)- acclimation. Focusing on the Prl signaling pathway, I identified a number of targets co-expressed with the prl receptor (prlr1) transcripts in FW-acclimated tilapia. These included genes encoding downstream signalling proteins and transcription factors such as jakmip, stat5b, mknk2b, junbb, socs2 and cish. By contrast, in SW-acclimated tilapia, genes associated with a pathway leading to the synthesis of myo-inositol, a metabolite that protects against hyperosmotic stress, were highly expressed in the gill, while stanniocalcin, a hypocalcaemic hormone, was activated in the kidney.Together, these findings shed light into the molecular mechanisms underlying the transcriptional regulation of prls by environmental osmotic and thermal stimuli. The discussion of the complex interaction between activators and repressors of transcription in Prl cells is extended to target tissues, where direct responses to environmental stimuli are integrated with hormonal action to optimize acclimation to FW and SW environments.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380405478Subjects--Topical Terms:

1178863
Animal sciences.
Subjects--Index Terms:

Comparative endocrinologyIndex Terms--Genre/Form:

554714
Electronic books.

Environmentally Sensitive Transcription Factors in the Prolactin Cell, Gill and Kidney of Mozambique Tilapia (Oreochromis mossambicus).
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