%0 Journal Article %J Gene %D 2014 %T The Jumonji gene family in Crassostrea gigas suggests evolutionary conservation of Jmj-C histone demethylases orthologues in the oyster gametogenesis and development. %A Alexandre Fellous %A Pascal Favrel %A Guo, Ximing %A Guillaume Rivière %K Animals %K Base Sequence %K Conserved Sequence %K Crassostrea %K Evolution, Molecular %K Gametogenesis %K Gene Expression Regulation, Developmental %K Jumonji Domain-Containing Histone Demethylases %K Molecular Sequence Data %K Multigene Family %K RNA, Messenger %X

Jumonji (Jmj) proteins are histone demethylases, which control the identity of stem cells. Jmj genes were characterized from plants to mammals where they have been implicated in the epigenetic regulation of development. Despite the Pacific oyster Crassostrea gigas representing one of the most important aquaculture resources worldwide, the molecular mechanisms governing the embryogenesis and reproduction of this lophotrochozoan species remain poorly understood. However, annotations in the C. gigas EST library suggested the presence of putative Jumonji genes, raising the question of the conservation of this family of histone demethylases in the oyster. Using Primer walking, 5'-RACE PCR and in silico analyses, we characterized nine Jumonji orthologues in the oyster, called Cg-Jmj, bearing conserved domains critical for putative histone demethylase activity. Phylogenic analyses revealed that oyster Jumonji cluster into two distinct groups: 'single-domain Jmj' and 'multi-domain Jmj', and define 8 subgroups corresponding to each cognate orthologues in metazoans. RT-qPCR investigations showed specific regulations of Cg-Jmj mRNAs during the early development and along the reproduction cycle. Furthermore, in situ and in toto hybridizations indicate that oyster Jumonji genes are transcribed mostly within the gonad in adult oysters whereas they display a ubiquitous expression during embryonic and larval development. Our study demonstrates the presence of nine Jumonji orthologues in the oyster C. gigas. Their domain conservation and their expression profile suggest an implication during reproduction and development, questioning about the epigenetic regulation by histone methylation in lophotrochozoans.

%B Gene %V 538 %P 164-75 %8 2014 Mar 15 %G eng %N 1 %R 10.1016/j.gene.2013.12.016 %0 Journal Article %J Gen Comp Endocrinol %D 2014 %T Neuroendocrine gene expression reveals a decrease in dopamine D2B receptor with no changes in GnRH system during prepubertal metamorphosis of silvering in wild Japanese eel. %A Jeng, Shan-Ru %A Wen-Shiun Yueh %A Pen, Yi-Ting %A Lee, Yan-Horn %A Chen, Guan-Ru %A Sylvie Dufour %A Chang, Ching-Fong %K Animals %K Cells, Cultured %K Dopamine %K Eels %K Female %K Follicle Stimulating Hormone, beta Subunit %K Gene Expression Regulation %K Gonadotropin-Releasing Hormone %K Immunoblotting %K Immunoenzyme Techniques %K Luteinizing Hormone, beta Subunit %K Metamorphosis, Biological %K Neurosecretory Systems %K Oocytes %K Ovary %K Real-Time Polymerase Chain Reaction %K Receptors, Dopamine D2 %K Reproduction %K Reverse Transcriptase Polymerase Chain Reaction %K RNA, Messenger %K Sexual Maturation %K Skin Pigmentation %X

Silvering is a prepubertal metamorphosis preparing the eel to the oceanic reproductive migration. A moderate gonad development occurs during this metamorphosis from the sedentary yellow stage to the migratory silver stage. The aim of this study was to elucidate the molecular aspects of various endocrine parameters of BPG axis at different ovarian developmental stages in wild yellow and silver female Japanese eels. The GSI of the sampled female eels ranged between 0.18 and 2.3%, corresponding to yellow, pre-silver and silver stages. Gonad histology showed changes from previtellogenic oocytes in yellow eels to early vitellogenic oocytes in silver eels. Both serum E2 and T concentrations significantly increased with ovarian development indicating a significant activation of steroidogenesis during silvering. In agreement with previous studies, significant increases in pituitary gonadotropin beta subunits FSH-β and LH-β transcripts were also measured by qPCR, supporting that the activation of pituitary gonadotropin expression is likely responsible for the significant ovarian development observed during silvering. We investigated for the first time the possible brain neuroendocrine mechanisms involved in the activation of the pituitary gonadotropic function during silvering. By analyzing the expression of genes representative of the stimulatory GnRH control and the inhibitory dopaminergic control. The transcript levels of mGnRH and the three GnRH receptors did not change in the brain and pituitary between yellow and silver stages, suggesting that gene expression of the GnRH system is not significantly activated during silvering. The brain transcript levels of tyrosine hydroxylase, limiting enzyme of DA synthesis did not change during silvering, indicating that the DA synthesis activity was maintained. In contrast, a significant decrease in DA-D2B receptor expression in the forebrain and pituitary was observed, with no changes in DA-D2A receptor. The decrease in the pituitary expression of DA-D2BR during silvering would allow a reduced inhibitory effect of DA. We may raise the hypothesis that this regulation of D2BR gene expression is one of the neuroendocrine mechanisms involved in the slight activation of the pituitary gonadotropin and gonadal activity that occur at silvering.

%B Gen Comp Endocrinol %V 206 %P 8-15 %8 2014 Sep 15 %G eng %R 10.1016/j.ygcen.2014.08.001