An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus)
Thesis (M.Sc. )--Memorial University of Newfoundland, 1997. Biology Bibliography: leaves 77-80. The remarkable cryptic patterning capability of flatfish gives rise to important questions about the regulatory processes which must be involved in the differential control of melanophores. Winter flounde...
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ftmemorialunivdc:oai:collections.mun.ca:theses4/16134 2023-05-15T17:23:27+02:00 An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) Mayo, Dennis Joseph, 1969- Memorial University of Newfoundland. Dept. of Biology 1996 x, 80 leaves : ill. Image/jpeg; Application/pdf http://collections.mun.ca/cdm/ref/collection/theses4/id/16134 Eng eng Electronic Theses and Dissertations (7.66 MB) -- http://collections.mun.ca/PDFs/theses/Mayo_DennisJoseph.pdf http://collections.mun.ca/cdm/ref/collection/theses4/id/16134 The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries Winter flounder--Color Melanophores Text Electronic thesis or dissertation 1996 ftmemorialunivdc 2015-08-06T19:21:05Z Thesis (M.Sc. )--Memorial University of Newfoundland, 1997. Biology Bibliography: leaves 77-80. The remarkable cryptic patterning capability of flatfish gives rise to important questions about the regulatory processes which must be involved in the differential control of melanophores. Winter flounder, Pleuronectes americanus, possess three distinct pattern components on its dark upper (ocular) surface that are important for cryptic patterning. These are the white spot, general background and dark band components that display differential chromatic responsiveness which has been studied using electrophysiological and pharmacological methods in the current work. -- In vitro experiments with K+ rich aggregating fluid (AF) or noradrenaline and phentolamine demonstrate that α-adrenoceptors mediate melanosome aggregation. -- Studies examining the effects of increasing concentrations of prazosin and yohimbine on melanosome aggregation evoked by electrical stimulation indicate that both α1- and α2-adrenoceptors play a role in melanosome aggregation, but there is a predominance of the latter. Experiments with atenolol suggest that there may be some β-adrenoceptor synergism involved in pigment aggregation. -- Topical application of low concentrations of soproterenol and noradrenaline enhance rates of in vitro melanosome dispersion in balanced salt solution which could be depressed with propranolol and suggests β-adrenoceptor mediation. The subtype of this adrenoceptor appears to be most likely the β2 conformation based on studies with terbutaline. Denervation of scale slips in 6-OH dopamine followed by incubation in a high concentration of isoproterenol and propranolol results in complete melanosome aggregation. Incubation of denervated scale slips in the same concentration of isoproterenol and phentolamine results in the blockade of pigment aggregation. This study shows that α- and β2-adrenoceptors play roles in pigment aggregation and dispersion respectively and that the melanophore response that is initiated is dependent upon neurotransmitter concentration. High concentrations of noradrenaline or isoproterenol evoke melanosome aggregation via α-adrenoceptors while low concentrations induce melanosome dispersion via β2-adrenoceptors. Thesis Newfoundland studies University of Newfoundland Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
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Open Polar |
collection |
Memorial University of Newfoundland: Digital Archives Initiative (DAI) |
op_collection_id |
ftmemorialunivdc |
language |
English |
topic |
Winter flounder--Color Melanophores |
spellingShingle |
Winter flounder--Color Melanophores Mayo, Dennis Joseph, 1969- An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
topic_facet |
Winter flounder--Color Melanophores |
description |
Thesis (M.Sc. )--Memorial University of Newfoundland, 1997. Biology Bibliography: leaves 77-80. The remarkable cryptic patterning capability of flatfish gives rise to important questions about the regulatory processes which must be involved in the differential control of melanophores. Winter flounder, Pleuronectes americanus, possess three distinct pattern components on its dark upper (ocular) surface that are important for cryptic patterning. These are the white spot, general background and dark band components that display differential chromatic responsiveness which has been studied using electrophysiological and pharmacological methods in the current work. -- In vitro experiments with K+ rich aggregating fluid (AF) or noradrenaline and phentolamine demonstrate that α-adrenoceptors mediate melanosome aggregation. -- Studies examining the effects of increasing concentrations of prazosin and yohimbine on melanosome aggregation evoked by electrical stimulation indicate that both α1- and α2-adrenoceptors play a role in melanosome aggregation, but there is a predominance of the latter. Experiments with atenolol suggest that there may be some β-adrenoceptor synergism involved in pigment aggregation. -- Topical application of low concentrations of soproterenol and noradrenaline enhance rates of in vitro melanosome dispersion in balanced salt solution which could be depressed with propranolol and suggests β-adrenoceptor mediation. The subtype of this adrenoceptor appears to be most likely the β2 conformation based on studies with terbutaline. Denervation of scale slips in 6-OH dopamine followed by incubation in a high concentration of isoproterenol and propranolol results in complete melanosome aggregation. Incubation of denervated scale slips in the same concentration of isoproterenol and phentolamine results in the blockade of pigment aggregation. This study shows that α- and β2-adrenoceptors play roles in pigment aggregation and dispersion respectively and that the melanophore response that is initiated is dependent upon neurotransmitter concentration. High concentrations of noradrenaline or isoproterenol evoke melanosome aggregation via α-adrenoceptors while low concentrations induce melanosome dispersion via β2-adrenoceptors. |
author2 |
Memorial University of Newfoundland. Dept. of Biology |
format |
Thesis |
author |
Mayo, Dennis Joseph, 1969- |
author_facet |
Mayo, Dennis Joseph, 1969- |
author_sort |
Mayo, Dennis Joseph, 1969- |
title |
An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
title_short |
An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
title_full |
An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
title_fullStr |
An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
title_full_unstemmed |
An in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (Pleuronectes americanus) |
title_sort |
in vitro study of α and β adrenoreceptors in melanosome differential aggregation and dispersion associated with cryptic patterning in winter flounder (pleuronectes americanus) |
publishDate |
1996 |
url |
http://collections.mun.ca/cdm/ref/collection/theses4/id/16134 |
genre |
Newfoundland studies University of Newfoundland |
genre_facet |
Newfoundland studies University of Newfoundland |
op_source |
Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries |
op_relation |
Electronic Theses and Dissertations (7.66 MB) -- http://collections.mun.ca/PDFs/theses/Mayo_DennisJoseph.pdf http://collections.mun.ca/cdm/ref/collection/theses4/id/16134 |
op_rights |
The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. |
_version_ |
1766112450473623552 |