Avian and Poultry Biology Reviews 16 (1), 2005
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INTRODUCTION
Endocrine
Disrupting Chemicals
Mary Ann Ottingera, Kristin E
Bruggerb and Leslie Touartc
a Department of Animal and
Avian Sciences,
bDuPont, Crop Protection
Products, SHRC Buildling 3115,
cUSEPA,
OPPTS/Of®ce of Science Coordination and Policy, 1200 Pennsylvania Avenue, N.W.,
Washington, DC20460, USA
The
papers in this dedicated issue of Poultry and Avian Biology
Reviews encompass topics that are
important in addressing the challenges of
characterizing the biological consequences of exposure to
endocrine active environmental chemicals.
These chemicals, termed endocrine disrupting chemicals
(EDCs)
have emerged as a critical issue for humans and wildlife as they are now
ubiquitous in
our environment and their effects are somewhat uncertain.
Several of the papers in this volume are
based on presentations given at the annual meeting of
the Society for Environmental Toxicology and
Chemistry
held in
in Avian Endocrine Testing at the Population
Level" focused on the effects of EDCs on avian species and
on methods for reliable detection and
characterization of the impact of speci®c chemicals.
Additionally,
we were fortunate to include papers from distinguished colleagues also working
in this
area and together the volume promises to cover a range
of important topics and concerns as well as
provide the background for understanding the breadth
of this issue.
--------------------------
Developmental
Toxicity in Japanese Quail Exposed to Hydroxylated Metabolites of PCBs in ovo
Krister Halldina*, AÊ ke Bergmana, Ingvar Brandta and BjoÈrn
BrunstroÈma
aDepartment
of Environmental Toxicology, Centre for Reproductive Biology in Uppsala (CRU),
Uppsala University, NorbyvaÈgen 18A, SE-75236 Uppsala, Sweden
bDepartment of Environmental
Chemistry,
ABSTRACT
Hydroxylatedmetabolites
of polychlorinated biphenyls (OH-PCBs) are present in plasma fromhumans,mammals, birds and fish.
Some
OH-PCBs compete with thyroxin for binding to the transport protein
transthyretin, possibly disturbing thyroid hormone
homeostasis. Furthermore, some OH-PCBs have shown
estrogenic activity. OH-PCBs have been found in unincubated avian
eggs, showing thatmaternal transfer of OH-PCBs occurs
in birds.However, studies on the toxicity in birds are lacking.Toinvesti-
gate possible effects of OH-PCBs on embryo
development, sexual differentiation, and the thyroid hormone systemwe adminis-
tered
2,3,30,40,5-pentachloro-4-biphenylol (4-OH-CB107; 750, 325 and 162.5 mgyegg)
and 2,20,3,40,5,50,6-heptachloro-4-
biphenylol (4-OH-CB187; 750,162.5 and 40 mgyegg)
toJapanese quail eggs via yolk injection.The major finding was that both
compounds caused a relatively high embryo lethality.
Embryos that survived the first days after administration appeared unaf-
fected, since no weight differences in hatchlings were
found and no differences in weight gain, reproductive variables or
plasma thyroid hormone concentrations were detected in
adults. The mechanism behind the lethality of 4-OH-CB107 and 4-
OH-CB187
in early embryos is unknown.The fact that both compounds aremajor PCB
metabolites inhuman plasma andinwild-
life, including avian eggs, warrants further studies
on their biological effects.
Keywords:
hydroxylated PCB, Japanese quail, embryo, development, endocrine disruption,
sexual behavior,
thyroid hormone
-------------------------
Biomarkers
for the Assessment of Avian Thyroid Disruption by Chemical Contaminants
F.M. Anne McNabb*
Department
of Biology, Virginia Tech.,
ABSTRACT
My
laboratory has evaluated several biomarkers for their sensitivity in detecting
thyroid disrupting effects of chemicals in birds.
The
biomarkers considered are ones that may be classed as effects biomarkers of
thyroid alterations, effects biomarkers of
target organ alterations and exposure biomarkers based
on mechanisms of action of thyroid disruptors. Our studies are based
on two types of thyroid disruptor chemicals,
ammoniumperchlorate and polychlorinated biphenyls, and their effects on thyroid
function of bobwhite quail, mallard ducks and herring gulls.
The most sensitive biomarker of altered thyroid function is thyroid
glandT4 content.
Large amounts of hormone storage are aunique feature of thyroid function and
hormone release fromthyroidal
stores to the circulation is the first response to
decreases in hormone synthesis or increases in hormone excretion. In contrast
to thyroidalT4 content,
plasmaT4 concentrations (an indicator of organismal thyroid status) and thyroid
weight (an indicator of
hypothalamic-pituitary-thyroid
axis activation) are relatively insensitive indicators of thyroid
disruption.The biomarkers of expo-
sure, target organ alterations and mechanismof
actionindicators thatwe evaluatedwere less sensitive than those thatmeasured
some aspect of thyroid function.
Keywords:
biomarkers, thyroid disruption, thyroid hormones, birds, perchlorate, PCBs
Suitability
of Some Additional Parameters in Reproduction Studies in Japanese Quail: Preliminary Experience
B.Selzsama*, L. Niemanna, C. Gerickeb and
aFederal Institute for
Risk Assessment,
bChariteÂ
UniversitaÈtsmedizin
ABSTRACT
Against
the background of ongoing discussions about the proposal for a newOECDguideline
for testing reproduction toxicity in
birds (OECD, 2000) andabout the best-suited test
designfor anaviantwo-generationtest, the inclusionofadditionalparameters
and methods is widely discussed. In one-generation
studies in Japanese quail (Coturnix coturnix japonica), we investigated a
number of these new endpoints such as spermatid count,
hormone concentrations (estradiol, LH, progesterone, testosterone,
T3,T4) and sex distribution in14-day old chicks.Data on these
parameters are presentedwith particular regard to untreated ani-
mals to show the physiological range and their
suitability is discussed.The regular determination of spermatid count,
serumcon-
centrations of testosterone (both sexes), estradiol
(in females only) and sex ratio is recommended as these variables provide
promising measurement endpoints.
Keywords:
Japanese quail, reproduction, spermatid count, hormones, sex ratio
In vivo and in vitro
Screening of Endocrine Disrupting Chemicals with Estrogenic activity in
Japanese Quail
Kiyoshi Shimadaa*, Yonju Haa, Akira Tsukadaa, Noboru Saitoa, Shinobu Maekawab, Makoto Nishizukab and Masayoshi
Imagawab
aLaboratory of Animal
Physiology, Graduate School of Bioagricultural Sciences,
bDepartment of Molecular
Biology, Graduate School of Pharmaceutical Sciences,
ABSTRACT
This
reviewpaper describes the (1) establishment of anin vitro method for screening
endocrine disrupting chemicalswith estro-
genic activity and (2) study on effects of nonylphenol
(NP) and octylphenol (OP) onmRNA expression of vitellogenin (VTG) II
and very low density lipoprotein (apoVLDL) II in the
liver of quail embryos. For in vitro screening, the cDNA of the ligand binding
domain of quail estrogen receptor (ER) a or
quail b was ligated into the gluthathione S-transferase expression vector and
expressed in E. coli.The fusion protein was used for
competitive enzyme immunoassay. Of the 20 compounds examined, nine
and five showed binding to ERa and ERb,
respectively. NP and OP showed the highest binding to ERa, and
bisphenol-A to
ER b, with
binding affinities relative to that of diethylstilbesterol (DES; 10ÿ9M) of
6% and 6.7%, respectively. For the in vivo
study, quail fertile eggs were treatedwith a single
injection of eitherNPorOP (10 and100 nmoleyegg,
in 20 ml) on day13 of incu-
bation.VTGII and apoVLDLIImRNA levels on day 15 of
incubation were determined by RT-PCR. Aweak but distinct expression
ofVTGII and ApoVLDLIImRNAwas observed after NPandOP,
indicating thatNPandOP could be endocrine disruptors in birds.
Keywords:
endocrine disrupters, estrogen receptor, competitive enzyme immunoassay
Endocrine
Disruption in Avian Reproduction: the Histological Analysis
Yukinori
Yoshimura* and Masanori Fujita
ABSTRACT
It is
important to determine the endpoints of endocrine disruption in birds.This
paper describes the effects of estrogenic chemi-
cals on the structure and function of avian
reproductive organs. No structural and functional abnormalities in reproductive
organs were identified in males or females orally
administered diethylstilbestrol (DES; 0.1mg or 1mgyl in
drinkingwater) from
birth to sexual maturation, although sexual maturation
was delayed in males. The most significant effects caused by in or on
ovo exposure to DESwere malformations of the
reproductive organs including feminizationwith ovotestes inmales and reten-
tion of the right-side oviduct in females.The
abnormalities becamemore pronounced in the adult phase, namely disorganization
of the seminiferous epithelium and reduced
development of epididymal tubules in males, and a failure of yellow follicles
to
grow and occlusion of the right-side oviduct in
females. Nonylphenol injected into laying birds was identified in the egg yolk,
suggesting that chemicals circulating in the blood
contaminate eggs.The contamination of eggs could affect the physiological
functions of offspring because it was evident that the
male offspring obtained from the hens orally administered DES had ovo-
testes.The sensitivity to endocrine disruptors may be
greater in the embryonic phase than post-hatching phase. It is suggested
that analyses of the effects of endocrine disruptors
on reproductive organs should include not only immature individuals but
also adult birds which have been raised from treated
embryos or the offspring of treated birds. The histological analysis of
abnormalities in the gonads and genital tracts may
enable one to judge the significant endpoints of endocrine disruption.
Keywords:
estrogenic chemicals, malformation of reproductive organs, histological
observations, effects on
offspring, Japanese quail