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Reproduction and development in Daph...

Kashian, Donna Rebecca.

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Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification./
Author:	Kashian, Donna Rebecca.
Description:	92 p.
Notes:	Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 1741.
Contained By:	Dissertation Abstracts International63-04B.
Subject:	Biology, Zoology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3049341
ISBN:	0493638865

Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification.
Kashian, Donna Rebecca.

Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification. - 92 p.

Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 1741.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2002.

<italic>Daphnia</italic> are frequently used in ecotoxicology to establish human and environmental health standards. <italic>Daphnia</italic> are model organisms due to their small size, short life cycle, ubiquitous distribution in surface waters, and key ecological role in aquatic food chains. Although <italic> Daphnia</italic> are routinely used in pesticide testing, standard <italic> Daphnia</italic> toxicity tests were developed before the knowledge or concern existed regarding chemicals that disrupt normal development and endocrine function of wildlife and humans. Thus, it is important to determine whether <italic> Daphnia</italic> can be used as efficient screens for these chemicals, and to establish their sensitivity to these compounds. Therefore, I modified the standard <italic>Daphnia</italic> bioassay to include sublethal endpoints likely to reflect endocrine related impairments (i.e. sex determination, growth rate, fecundity), and investigated the role of detoxification enzymes in <italic> Daphnia</italic>. First, vertebrate hormones were screened to compare developmental responses of <italic>Daphnia</italic> to similar responses observed in vertebrate systems. Natural and synthetic vertebrate hormones assayed included β-estradiol, gonadotropin, hydrocortisone, insulin, melatonin, progesterone, somatostatin, testosterone, thyroxine, ICI-182,780 (antiestrogen), R-1881 (androgen) and diethylstilbestrol (estrogenic). Second, I assayed several pesticides reported as having endocrine disrupting activity in vertebrate systems: o<super>′ </super>p<super>′</super>-DDT, Di-<italic>n</italic>-butyl phthalate, toxaphene (estrogenic); p<super>′</super>p-DDE, linuron (androgenic); acetochlor, alachlor, metribuzin (thyroid activity); 2,4-D (lutenizing hormone activity). I also evaluated pesticides with unknown effects on vertebrate endocrine systems: chlorosulfuran, cyanazine, diflubenzuron, metolachlor and diquat. Finally, I established the potential for <italic>Daphnia</italic> to acclimate to a model chemical (the insecticide toxaphene) <italic>via</italic> P-450 detoxification enzymes.

ISBN: 0493638865Subjects--Topical Terms:

1018632
Biology, Zoology.

Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification.
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100 1 $a Kashian, Donna Rebecca. $3 1251288
245 1 0 $a Reproduction and development in Daphnia: The role of hormones, pesticides and detoxification.
300 $a 92 p.
500 $a Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 1741.
500 $a Supervisor: Stanley I. Dodson.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2002.
520 $a <italic>Daphnia</italic> are frequently used in ecotoxicology to establish human and environmental health standards. <italic>Daphnia</italic> are model organisms due to their small size, short life cycle, ubiquitous distribution in surface waters, and key ecological role in aquatic food chains. Although <italic> Daphnia</italic> are routinely used in pesticide testing, standard <italic> Daphnia</italic> toxicity tests were developed before the knowledge or concern existed regarding chemicals that disrupt normal development and endocrine function of wildlife and humans. Thus, it is important to determine whether <italic> Daphnia</italic> can be used as efficient screens for these chemicals, and to establish their sensitivity to these compounds. Therefore, I modified the standard <italic>Daphnia</italic> bioassay to include sublethal endpoints likely to reflect endocrine related impairments (i.e. sex determination, growth rate, fecundity), and investigated the role of detoxification enzymes in <italic> Daphnia</italic>. First, vertebrate hormones were screened to compare developmental responses of <italic>Daphnia</italic> to similar responses observed in vertebrate systems. Natural and synthetic vertebrate hormones assayed included β-estradiol, gonadotropin, hydrocortisone, insulin, melatonin, progesterone, somatostatin, testosterone, thyroxine, ICI-182,780 (antiestrogen), R-1881 (androgen) and diethylstilbestrol (estrogenic). Second, I assayed several pesticides reported as having endocrine disrupting activity in vertebrate systems: o<super>′ </super>p<super>′</super>-DDT, Di-<italic>n</italic>-butyl phthalate, toxaphene (estrogenic); p<super>′</super>p-DDE, linuron (androgenic); acetochlor, alachlor, metribuzin (thyroid activity); 2,4-D (lutenizing hormone activity). I also evaluated pesticides with unknown effects on vertebrate endocrine systems: chlorosulfuran, cyanazine, diflubenzuron, metolachlor and diquat. Finally, I established the potential for <italic>Daphnia</italic> to acclimate to a model chemical (the insecticide toxaphene) <italic>via</italic> P-450 detoxification enzymes.
520 $a This modified assay was more sensitive than those classically used for <italic> Daphnia</italic> in ecotoxicology, detecting sublethal but ecologically relevant effects. The use of <italic>Daphnia</italic> as a model system in both toxicological and ecological studies is therefore warranted; however, the inconsistencies observed in the response of <italic>Daphnia</italic> to vertebrate hormones suggest that care must be taken in extrapolating results in which daphnid biology is not comparable to that of vertebrates. This research demonstrates that the standard approach of pesticides screening using <italic>Daphnia</italic> can be augmented to include additional parameters that reflect endocrine related processes and account for the potential of acclimation.
590 $a School code: 0262.
650 4 $a Biology, Zoology. $3 1018632
650 4 $a Health Sciences, Toxicology. $3 1017752
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710 2 0 $a The University of Wisconsin - Madison. $3 626640
773 0 $t Dissertation Abstracts International $g 63-04B.
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790 1 0 $a Dodson, Stanley I., $e advisor
791 $a Ph.D.
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856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3049341