Abstracts - Society for Developmental Biology

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food packaging and dentistry, is often exposed in life. Animal studies indicate that exposure to BPA may affect brain and
testis gonocytes development in embryos. However the detailed phenotypes and pathogenetic degree according to exposure
time, especially with regard to the sex relative hormone of brain, testis gonocytes and sperm analysis have not been
clarified. We therefore studied developmental retardation of brain, testis gonocytes according to BPA exposure time. And
we confirmed them with tissue, sex relative hormone level and sperm analysis. We orally injected with 20 μg/kg of BPA
dissolved in sesame oil to pregnant female rat and 200 μg/kg to newborn male rat by period which is embryonic day 0,
embryonic day 12 and neonatal to postnatal day (PND) 20. Histological characteristics of male rat brain and testis
gonocytes were processed immunohistochemistry and hormone was measured serum hormone level by radioimmunoassay
and AR, GnRH-R, FSH, LHβ, ERα,β mRNA expression by quantitative RT-PCR at PND 20. And we measured sperm
motility and number by computer assisted sperm analysis (CASA) at 8 weeks. In this study, we confirmed differences of
development of brain and testis gonocytes according to BPA exposure time. And we also confirmed differences of sex
relative hormone level and reduction of reproductive capacity according to development of brain and testis gonocytes. As
BPA has been exposed human populations, further studies are warranted to assess the effects of BPA on human fertility.
Program/Abstract # 153
Requirement of Co-Smad independent BMP canonical Smad signaling for the specification process of the anterior
rhombic lip during cerebellum development
Kwan, Kin Ming; Tong, Ka Kui, The Chinese University of Hong Kong School of Life Sciences, Shatin, Hong Kong
Cerebellum is an important organ in the central nervous system for coordinating body movement and balancing. Its
development involves complicated cellular and molecular events controlled by various signaling pathways. Bone
morphogenetic protein (BMP) has showed to be involved in these processes.However, the detail molecular mechanism of
the Smad proteins usage, the downstream mediator of BMP signaling pathway, is not clear. In this study, we utilized the
En1-driven Cre to conditionally inactivate Smad1, Smad5 and Smad4 in the mouse embryonic cerebellum. Our results
demonstrated that Smad1and Smad5 are required in a functional redundant manner for the specification process of the
anterior rhombic lip (ARL) during cerebellum development. Inactivation of both Smad1 and Smad5 resulted in the
reduction of granule cell precursor numberand the loss of nuclear transitory zone leading to the loss of parts of deep
cerebellar nuclei. In addition, the migration of Purkinje cells was also affected. Surprisingly, inactivation of Smad4 only
resulted in mild cerebellar defects. The Msx2 expression in the ARL was not abolished suggesting that R-Smads were still
transcriptional active in the absence of Smad4. Thus, our results support a co-Smad independency in the BMP signaling
during the cerebellum development and challenge our current understanding of the BMP canonical Smad signaling.
Program/Abstract # 154
Embryonic DNA repair and gender are risk factors in ethanol embryopathies in oxoguanine glycosylase 1 (OGG1)
knockout mice: A role for oxidatively damaged DNA and protection by a free radical spon trapping agent
Miller, Lutfiya; Wells, Peter, University of Toronto, Toronto, Canada
Reactive oxygen species (ROS) have been implicated in the mechanism of Fetal Alcohol Spectrum Disorders (FASD). To
determine the involvement of ROS-mediated embryonic oxidative DNA damage, DNA repair-deficient oxoguanine
glycosylase 1 (OGG1) knockout (KO), heterozygous (HET) or wild-type (WT) embryos were exposed in culture to ethanol
(EtOH) (2 or 4 mg/ml) on gestational day (GD) 9 (plug = GD 1), with or without pretreatment with the free radical spin
trap phenylbutylnitrone (PBN) (0.125 mM). Visceral yolk-sacs were genotyped for DNA repair status and gender. EtOH
caused a concentration-dependent decrease in anterior neuropore closure (ANC), somite development, turning, crownrump
length, yolk sac diameter and head length (p < 0.001) in all 3 ogg1 genotypes, with a further ogg1 gene-dependent
decrease in KO embryos for ANC, somite development, turning, crown-rump length and head length (p < 0.05), and a
genotype-dependent correlation between head length and ANC(p < 0.01). PBN pretreatment blocked most EtOH
embryopathies (p < 0.001), although slightly so in KO embryos. Oxidatively damaged DNA determined as8-oxo-2’-
deoxyguanosine (8-oxodG), which is repaired by OGG1, was measured in single GD 11 embryos 6 hours after maternal
EtOH treatment (4 g/kg ip). Preliminary data suggest that EtOH-initiated 8-oxodG was greater in KO embryos. Head
length and ANC were reduced in female embryos independent of treatment or ogg1 genotype, whereas the ratio of female
to male KOs was increased compared to HET and WT embryos (p < 0.001). These results suggest that ROS-initiated
embryonic DNA oxidation is involved in EtOH embryopathies, and embryonic DNA repair status and gender may be
determinants of embryopathic risk. (Support: CIHR)
Program/Abstract # 155
Valproic acid induces p53 activation via hyperacetylation and increases cellular apoptosis leading to limb