Congress Abstracts - Society for Developmental Biology

TACC3 was localized around the DNA at metaphase I and II stages, concentrated tightly to the spindles, surrounding the
chromosomes. Levels of TACC3 expression reduced after fertilization and TACC3 was undetectable after pronuclei formation. In
addition, TACC3 expression was monitored after inhibition of Aurora-A kinase which is a protein proposed to phosphorylate TACC3
for its proper recruitment on the microtubules. After Aurora-A kinase inhibition, formation of meiotic spindle and chromosome
alignment became impaired, polar body extrusion of oocytes was reduced and as progression of meiosis was distorted, oocytes
exhibited reduced developmental competence. It is concluded that TACC3 has a direct function in oocyte meiosis and proper spindle
assembly.
Program/Abstract # 172
Morphologic and molecular markers indicate developmental maturation-competence of mouse and human oocytes
Levi, Mattan (Tel Aviv University, Israel); Shulman, Adrian; Ghetler, Yehudith (IVF Unit, Meir Medical Center, Israel); Shalgi, Ruth
(Tel Aviv University, Israel)
Background: Developmental maturation competence of mouse oocytes is correlated with central germinal vesicle (GV) and regulated
by microtubules (MTs) and the presence of a chromatin ring. Fyn kinase is localized at the spindle and cortex of mouse oocytes and
regulates oocyte maturation and MTs stabilization. The aim of the current study was to examine whether the position of the GV in
mouse and human oocytes correlates with molecular and morphologic parameters as well as with maturation-competence. Methods:
The spatial localization of GV and nucleolus, presence of a chromatin ring, localization of Fyn, MTs density and oocyte maturation
were assessed in 153 human oocytes, 418 oocytes of young mice (2 months old) and 146 oocytes of old mice (12 months old) by
confocal laser scanning microscope or differential interference contrast optics. Results: GV location was peripheral and ageindependent
in most of the human oocytes but age-dependent in mice oocytes; it was central in most of the young-mice oocytes and
peripheral in most of the old-mice oocytes. Central GV, whether in human or mouse oocytes, correlated with central nucleolus,
absence of Fyn at the GV, dense MTs network and high maturation competence; whereas peripheral GV correlated with peripheral
nucleolus, presence of Fyn at the GV, flimsy MTs network and low maturation competence. No correlation was observed between GV
position and presence of chromatin ring. Conclusion: Our results suggest that the central location of GV within the oocytes, absence of
Fyn at the GV and presence of thick filamentous MTs at the ooplasm, can serve as predictors of successful developmental maturation
and provide new insights for clinical in vitro maturation treatment.
Program/Abstract # 173
Oct4 is a useful marker for understanding PGC migration in Monodelphis domestica
Wright, Amelia; Cruz, Yolanda (Oberlin College, USA)
No satisfactory method or reliable marker currently exists for detecting primordial germ cells (PGCs) in marsupial embryos. Oct4, a
cellular pluripotency marker, has been used extensively in mouse studies to track PGC migration during embryonic development.
Oct4 is expressed in mouse tissues throughout prenatal development, but is restricted to the inner cell mass (ICM) at the blastocyst
stage and to the epiblast after implantation. PGCs are specified from the epiblast at E7.0 and remain pluripotent through adulthood.
We tested the hypothesis that Oct4 could be used as a PGC marker in the lab opossum, Monodelphis domestica, to track PGC
migration in marsupial embryos. M. domestica is an excellent marsupial model for studying PGC migration due to its short gestation
period and accessible embryos that lie free in the uterine cavity until day 13 of a 15-day gestation. Avidin-biotin-enhanced
immunohistochemical analysis was used to detect Oct4 in opossum embryos of equivalent developmental stages to mouse E7.0
through E9.0. Our results indicate that Oct4-positive cells are detectable in day-10 through day-12 opossum embryos, in precisely the
regions where PGCs would be located in developmentally equivalent stages of mouse. Thus, Oct4 appears to be a useful marker for
tracking the migration of marsupial PGCs during embryogenesis. More importantly, our findings are consistent with the emerging role
of Oct4 in maintenance of cellular pluripotency in the mammalian germ line.
Program/Abstract # 174
Oct60 is involved in the PGC formation as a germplasm component
Morichika, Keisuke; Shimada, Keigo (Rikkyo University, Japan); Kubo, Hideo (Tokyo Metropolitan Institute of Medical Science,
Japan); Kinoshita, Tsutomu (Rikkyo University, Japan)
Primordial germ cells (PGCs) are germline cells that are specified from early embryogenesis. In mammal, Oct3/4 is expressed
ubiquitously after fertilization. The expression of Oct3/4 is restricted in the inner cell mass at blastocyst stage, and thereafter detected
only in PGCs. It is known that Oct3/4 conditional KO mouse showed depletion of germ cells. Oct3/4 belongs to transcriptional factor
of POU family class V. In Xenopus, three POU class V genes, Oct60, Oct25 and Oct91 are expressed in different manner. Oct60 is
maternally expressed in oocyte, but their role in PGC formation remains unknown. In this study, we examined a role of Oct60 in PGC
formation. In order to examine the gene expression of PGC, synthesized RNAs of Venus-DEADSouth 3’UTR were injected into
vegetal cortex of one-cell stage embryo, and GFP-positive PGCs were isolated form dissociated cells of endodermal region. RT-PCR
analysis showed that among three POU-V genes, Oct60 is specifically expressed in PGC. Immunocytochemical examination
demonstrated that Oct60 protein is localized in germ plasm and PGCs after gastrulation. To clarify the role of Oct60 in PGC
formation, we injected mRNA of Oct60 into vegetal cortex of one-cell-stage embryo. Overexpression of Oct60 caused the upregulation
of PGC marker gene DEADEnd1 and the down-regulation of pan-endodermal marker Sox17α at gastrula stage. In addition,
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