Onset of meiosis in the chicken embryo; evidence of a role for retinoic acid

Smith, Craig A.; Roeszler, Kelly N.; Bowles, Josephine; Koopman, Peter; Sinclair, Andrew H.

doi:10.1186/1471-213x-8-85

Cited by 136 publications

(184 citation statements)

References 36 publications

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“…cSYCP1 and cSYCP2 were initially expressed on E6.0 in both testis and ovary, whereas cSYCP3 was initially expressed on E6.0 in females and on E8.0 in males. The onset of meiosis in chickens occurs first in female gonads on E15.5 (Smith et al 2008). The duration-dependent expression of cSYCP family members in the present study calls into question the idea that cSYCP family members are specific to meiotic prophase I or are initially expressed only after pre-meiotic development of germ cells.…”

Section: Discussionmentioning

confidence: 38%

“…The same RNA samples were hybridised with probes made from the endogenous housekeeping gene, chicken glyceraldehyde-3-phosphate dehydrogenase (cGAPDH) for normalisation. numerous in the female gonad (Hughes 1963, Smith et al 2008. In male chickens, PGCs undergo mitotic arrest: they stop dividing and remain as pro-spermatogonia at the G1 stage of the cell cycle until hatching (Kirby & Froman 2000, Smith et al 2008.…”

Section: Discussionmentioning

confidence: 99%

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Expression pattern of meiosis associated SYCP family members during germline development in chickens

Zheng

Rengaraj²,

Choi³

et al. 2009

Reproduction

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Synaptonemal complexes (SCs) are associated with synapsis of homologous chromosomes, chiasmata distribution, recombination and segregation of chromosomes during the extended prophase of meiosis I. Three isoforms of SC proteins, SYCP1, SYCP2 and SYCP3, were identified as the structural proteins of SCs, and may be involved in the assembly and disassembly of SCs. The aim of this present study is to determine the pattern of expression of chicken homologues of SYCP family members during ovarian and testicular development. Protein sequence analysis using CLUSTAL X revealed that the sequences and potential phosphorylation sites of chicken SYCP family proteins were highly conserved with mammalian homologues of SYCP family proteins. Quantitative real-time-PCR and in situ hybridisation analysis revealed that chicken SYCP family members were differentially expressed during ovarian and testicular development. During ovarian development, all chicken SYCP family members were detected in primordial germ cells (PGCs) until embryonic day (E) 8.0; the expression continued in proliferating pre-meiotic oogonia until E15.5 and was upregulated in meiotic prophase I oocytes until hatching. After hatching, all chicken SYCP family members were detected at a low level until 24-weeks-old. During testicular development, all chicken SYCP family members were detected in PGCs until E13.0; the expression continued in pro-spermatogonia and proliferating spermatogonia for up to 8 weeks, and was upregulated in meiotic prophase I spermatocytes in adults. Our data demonstrate the expression pattern of meiosis associated SYCP family members during ovarian and testicular development in chickens.

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Section: Discussionmentioning

confidence: 38%

Section: Discussionmentioning

confidence: 99%

Expression pattern of meiosis associated SYCP family members during germline development in chickens

Zheng

Rengaraj²,

Choi³

et al. 2009

Reproduction

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“…In the female embryo, miR181a* expression was down-regulated gradually as female embryonic gonads developed; however, the NR6A1 transcript was increased dramatically, particularly around day 13.5. Smith et al (39) reported that germ cells in the chicken female gonad initiate meiosis at around E12.5, at which time STRA8 is up-regulated in the female left gonad. In contrast to the female embryo, miR181a* was highly expressed in male embryonic gonads; however, NR6A1 expression was suppressed after E13.5 (39).…”

Section: Specific Analysis Of the Target Gene Transcript For The Regumentioning

confidence: 99%

“…Smith et al (39) reported that germ cells in the chicken female gonad initiate meiosis at around E12.5, at which time STRA8 is up-regulated in the female left gonad. In contrast to the female embryo, miR181a* was highly expressed in male embryonic gonads; however, NR6A1 expression was suppressed after E13.5 (39). Thus, we propose that miR-181a* and NR6A1 could be closely related to the regulatory pathways of meiotic differentiation in chicken PGCs.…”

Section: Specific Analysis Of the Target Gene Transcript For The Regumentioning

confidence: 99%

MicroRNA-mediated posttranscriptional regulation is required for maintaining undifferentiated properties of blastoderm and primordial germ cells in chickens

Lee

Hwang

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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MicroRNAs (miRNAs) play a critical role in determining the differentiation fate of pluripotent stem cells and germ cells in mammals. However, the mechanism(s) of miRNA-mediated posttranscriptional regulation with regard to lineage specification and differentiation in chick development require further investigation. Therefore, we conducted miRNA expression profiling to explore specific miRNA signatures in undifferentiated blastoderm and primordial germ cells (PGCs). We identified seven miRNAs that are highly expressed in blastoderm and 10 that are highly expressed in PGCs. In this study, miR-302a and miR-456 for blastoderm and miR-181a* for PGCs were analyzed further for their target transcripts and regulatory pathways. Both miR-302a and miR-456 bound directly to the sex-determining region Y box 11 transcript and could act as posttranscriptional coregulators to maintain the undifferentiated state of the chicken blastoderm through the suppression of somatic gene expression and differentiation. Moreover, miR-181a* showed a bifunctional role in PGCs by binding to two different transcripts. miR-181a* inhibited the somatic differentiation of PGCs by silencing homeobox A1 expression. Additionally, miR-181a* prevented PGCs from entering meiosis through the repression of the nuclear receptor subfamily 6, group A, member 1 transcript. Collectively, our data demonstrate that in chickens miRNAs intrinsically regulate the differentiation fate of blastoderms and PGCs and that the specific timing of germ cell meiosis is controlled through miRNA expression.A t stage X, the chicken blastoderm consists of 40,000-60,000 undifferentiated embryonic cells and is able to develop pluripotent stem cells through in vitro culture (1). During chicken germline development, primordial germ cells (PGCs) first appear from the epiblast in the blastoderm and translocate to the hypoblast area of the pellucida (2, 3). During gastrulation, PGCs circulate through the vascular system and settle down in the gonadal anlagen. Such a differentiation pathway, including germ cell lineage during chicken embryo development, is a systematic process, governed by the concerted action of multiple unknown regulatory mechanisms (4-6).MicroRNAs (miRNAs) are small, noncoding RNAs ranging from 18 to 23 nucleotides that posttranscriptionally regulate gene expression in various tissues and cell types. Typically, miRNAs act as specific regulators of gene expression and are capable of controlling the fate of cells in a time-and tissue-specific manner (7, 8) through regulation of cellular differentiation, in addition to developmental patterning and morphogenesis (9-11). To date, several miRNA profiles have been classified as ESC-specific miRNAs, including miR-290-295 and miR-302-367 clusters (12, 13). However, both the miRNA expression profiling and posttranscriptional gene regulation for lineage specification, commitment, and differentiation during chicken embryo development remain largely uninvestigated. It has been shown recently that miRNA biogenesis and specific expr...

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“…Evidence is mounting that RA may trigger entry into meiosis not just in mouse and rat, as detailed above, but also in chickens (Smith et al 2008) and amphibians (Wallacides et al 2009). Although a role for RA in initiating meiosis in humans has not been demonstrated so far, an anterior site of meiosis initiation -originating near the rete ovarii which connects the gonad and mesonephros -is observed in many mammalian species including humans (Byskov 1975, Bendsen et al 2006.…”

Section: How Does Ra Work Its Magic?mentioning

confidence: 99%

Sex determination in mammalian germ cells: extrinsic versus intrinsic factors

Bowles

Koopman²

2010

Reproduction

Self Cite

107

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Mammalian germ cells do not determine their sexual fate based on their XX or XY chromosomal constitution. Instead, sexual fate is dependent on the gonadal environment in which they develop. In a fetal testis, germ cells commit to the spermatogenic programme of development during fetal life, although they do not enter meiosis until puberty. In a fetal ovary, germ cells commit to oogenesis by entering prophase of meiosis I. Although it was believed previously that germ cells are pre-programmed to enter meiosis unless they are actively prevented from doing so, recent results indicate that meiosis is triggered by a signaling molecule, retinoic acid (RA). Meiosis is avoided in the fetal testis because a male-specifically expressed enzyme actively degrades RA during the critical time period. Additional extrinsic factors are likely to influence sexual fate of the germ cells, and in particular, we postulate that an additional male-specific fate-determining factor or factors is involved. The full complement of intrinsic factors that underlie the competence of gonadal germ cells to respond to RA and other extrinsic factors is yet to be defined.

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Onset of meiosis in the chicken embryo; evidence of a role for retinoic acid

Cited by 136 publications

References 36 publications

Expression pattern of meiosis associated SYCP family members during germline development in chickens

Expression pattern of meiosis associated SYCP family members during germline development in chickens

MicroRNA-mediated posttranscriptional regulation is required for maintaining undifferentiated properties of blastoderm and primordial germ cells in chickens

Sex determination in mammalian germ cells: extrinsic versus intrinsic factors

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