Search for the genes involved in oocyte maturation and early embryo development in the hen

<p>Abstract</p> <p>Background</p> <p>The initial stages of development depend on mRNA and proteins accumulated in the oocyte, and during these stages, certain genes are essential for fertilization, first cleavage and embryonic genome activation. The aim of this study was first to search for avian oocyte-specific genes using an <it>in silico </it>and a microarray approaches, then to investigate the temporal and spatial dynamics of the expression of some of these genes during follicular maturation and early embryogenesis.</p> <p>Results</p> <p>The <it>in silico </it>approach allowed us to identify 18 chicken homologs of mouse potential oocyte genes found by digital differential display. Using the chicken Affymetrix microarray, we identified 461 genes overexpressed in granulosa cells (GCs) and 250 genes overexpressed in the germinal disc (GD) of the hen oocyte. Six genes were identified using both <it>in silico </it>and microarray approaches. Based on GO annotations, GC and GD genes were differentially involved in biological processes, reflecting different physiological destinations of these two cell layers. Finally we studied the spatial and temporal dynamics of the expression of 21 chicken genes. According to their expression patterns all these genes are involved in different stages of final follicular maturation and/or early embryogenesis in the chicken. Among them, 8 genes (<it>btg4</it>, <it>chkmos</it>, <it>wee</it>, <it>zpA</it>, <it>dazL</it>, <it>cvh</it>, <it>zar1 </it>and <it>ktfn) </it>were preferentially expressed in the maturing occyte and <it>cvh</it>, <it>zar1 </it>and <it>ktfn </it>were also highly expressed in the early embryo.</p> <p>Conclusion</p> <p>We showed that <it>in silico </it>and Affymetrix microarray approaches were relevant and complementary in order to find new avian genes potentially involved in oocyte maturation and/or early embryo development, and allowed the discovery of new potential chicken mature oocyte and chicken granulosa cell markers for future studies. Moreover, detailed study of the expression of some of these genes revealed promising candidates for maternal effect genes in the chicken. Finally, the finding concerning the different state of rRNA compared to that of mRNA during the postovulatory period shed light on some mechanisms through which oocyte to embryo transition occurs in the hen.</p

Protein expression reveals a molecular sexual identity of avian primordial germ cells at pre-gonadal stages

International audienceIn poultry, in vitro propagated primordial germ cells (PGCs) represent an important tool for the cryopreservation of avian genetic resources. However, several studies have highlighted sexual differences exhibited by PGCs during in vitro propagation, which may compromise their reproductive capacities. To understand this phenomenon, we compared the proteome of pregonadal migratory male (ZZ) and female (ZW) chicken PGCs propagated in vitro by quantitative proteomic analysis using a GeLC-MS/MS strategy. Many proteins were found to be differentially abundant in chicken male and female PGCs indicating their early sexual identity. Many of the proteins more highly expressed in male PGCs were encoded by genes localised to the Z sex chromosome. This suggests that the known lack of dosage compensation of the transcription of Z-linked genes between sexes persists at the protein level in PGCs, and that this may be a key factor of their autonomous sex differentiation. We also found that globally, protein differences do not closely correlate with transcript differences indicating a selective translational mechanism in PGCs. Male and female PGC expressed protein sets were associated with differential biological processes and contained proteins known to be biologically relevant for male and female germ cell development, respectively. We also discovered that female PGCs have a higher capacity to uptake proteins from the cell culture medium than male PGCs. This study presents the first evidence of an early predetermined sex specific cell fate of chicken PGCs and their sexual molecular specificities which will enable the development of more precise sex-specific in vitro culture conditions for the preservation of avian genetic resources

Search for the genes involved in oocyte maturation and early embryo development in the hen-0

cells (GCs). Inside the oocyte, the perivitelline membrane is covered by extra-embryonic RNA. At the top of the oocyte, the germinal disc (GD) is visible. The GD with the overlying GCs constituted the germinal disc region (GDR). Two hatched area represent two different samples used in this study. The GDR comprises the GD and the lowest possible number of GCs, and GCs comprises by the GCs located in the vicinity of the GDR. Both samples are localized on the apical part of the oocyte.<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p

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O biological replicates. Total GDR and GC RNA from different preovulatory follicles (F1 to F6), and total GDR RNA from just ovulated oocytes and early embryos at 6.5 h, 12 h, 24 h, 36 h and 48 h post ovulation were extracted as described in the . Unsupervised hierarchical clustering of biological samples was performed using Cluster 3.0 software as described in the . Node correlation thresholds are indicated.<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p

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(L), heart (H), skin (S), brain (B), pectoralis muscle (M), lung (Lu) and pituitary gland (Pg) and real time PCR was performed as described in the . Ribosomic RNA 18S was used as a reporter gene. The negative control (water) is indicated as (C-). The results represent the means ± SEM. The same letters indicate that differences were not significant. Different letters indicate that differences were significant (p < 0.05).<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p

Search for the genes involved in oocyte maturation and early embryo development in the hen-2

Esents the total number of overexpressed genes in one comparison. The overlapping areas represent overexpressed genes common for different comparisons. Genes identified by the approach and found to be overexpressed in different comparisons on the chips are indicated.<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p

Search for the genes involved in oocyte maturation and early embryo development in the hen-1

Circle represents the total number of differentially expressed genes in one comparison. The overlapping areas represent differentially expressed genes common for different comparisons.<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p

Search for the genes involved in oocyte maturation and early embryo development in the hen-7

O biological replicates. Total GDR and GC RNA from different preovulatory follicles (F1 to F6), and total GDR RNA from just ovulated oocytes and early embryos at 6.5 h, 12 h, 24 h, 36 h and 48 h post ovulation were extracted as described in the . Supervised hierarchical clustering of genes was performed using Cluster 3.0 software as described in the . Five clusters are shown (C1 to C5). Node correlation thresholds are indicated for each cluster.<p><b>Copyright information:</b></p><p>Taken from "Search for the genes involved in oocyte maturation and early embryo development in the hen"</p><p>http://www.biomedcentral.com/1471-2164/9/110</p><p>BMC Genomics 2008;9():110-110.</p><p>Published online 29 Feb 2008</p><p>PMCID:PMC2322995.</p><p></p