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

Abstract

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.

Chromosomal Axis Formation and Meiotic Progression in Chicken Oocytes: A Quantitative Analysis

“…In agreement with these data from classical histological sections, the SC protein SYCP3 is first detectable by immunofluorescence on E15.5 in female chicken gonads [Smith et al, 2008;Zheng et al, 2009]. The only quantitative analysis of chicken oogenesis was performed using histological sections of chicken ovaries from E15 to the day of hatching [Hughes, 1963].…”

The Chromosomes of Birds during Meiosis

“…1 b, c). Subsequently, sequence alignment and expression analyses showed that the 3 major SC proteins SYCP1, SYCP2, and SYCP3 share basic structural features in birds and mammals and are present in chicken gonads at the moment of meiosis [Zheng et al, 2009]. The percentage identity between chicken and mammalian SYCP proteins over the entire alignment indicates different levels of conservation, with the highest similarity for SYCP3 [Zheng et al, 2009].…”

“…Subsequently, sequence alignment and expression analyses showed that the 3 major SC proteins SYCP1, SYCP2, and SYCP3 share basic structural features in birds and mammals and are present in chicken gonads at the moment of meiosis [Zheng et al, 2009]. The percentage identity between chicken and mammalian SYCP proteins over the entire alignment indicates different levels of conservation, with the highest similarity for SYCP3 [Zheng et al, 2009]. In addition to specific SC proteins, the cohesin component SMC3 is also present on the meiotic axes of chickens and other birds from leptotene to late diplotene [Pigozzi, 2008;del Priore and Pigozzi, 2012] and is a component of the chromatin axes of lampbrush bivalents in the period of pre-vitellogenesis [Krasikova et al, 2005].…”

Evolutionary history of the mammalian synaptonemal complex

“…Furthermore, the evolutionary relationship between NO145 and SYCP2 opened additional questions about a potential last common ancestor of both proteins and the point of their separation. It was of avail that the chicken SYCP2 was characterized as the only non-mammalian orthologue just a few years ago (Zheng et al 2009). …”