BackgroundThe geese have strong broodiness and poor egg performance. These characteristics are the key issues that hinder the goose industry development. Yet little is known about the mechanisms responsible for follicle development due to lack of genomic resources. Hence, studies based on high-throughput sequencing technologies are needed to produce a comprehensive and integrated genomic resource and to better understand the biological mechanisms of goose follicle development.Methodology/Principal FindingsIn this study, we performed de novo transcriptome assembly and gene expression analysis using short-read sequencing technology (Illumina). We obtained 67,315,996 short reads of 100 bp, which were assembled into 130,514 unique sequences by Trinity strategy (mean size = 753bp). Based on BLAST results with known proteins, these analyses identified 52,642 sequences with a cut-off E-value above 10−5. Assembled sequences were annotated with gene descriptions, gene ontology and clusters of orthologous group terms. In addition, we investigated the transcription changes during the goose laying/broodiness period using a tag-based digital gene expression (DGE) system. We obtained a sequencing depth of over 4.2 million tags per sample and identified a large number of genes associated with follicle development and reproductive biology including cholesterol side-chain cleavage enzyme gene and dopamine beta-hydroxylas gene. We confirm the altered expression levels of the two genes using quantitative real-time PCR (qRT-PCR).Conclusions/SignificanceThe obtained goose transcriptome and DGE profiling data provide comprehensive gene expression information at the transcriptional level that could promote better understanding of the molecular mechanisms underlying follicle development and productivity.

BackgroundRecent functional studies have demonstrated that the microRNAs (miRNAs) play critical roles in ovarian gonadal development, steroidogenesis, apoptosis, and ovulation in mammals. However, little is known about the involvement of miRNAs in the ovarian function of fowl. The goose (Anas cygnoides) is a commercially important food that is cultivated widely in China but the goose industry has been hampered by high broodiness and poor egg laying performance, which are influenced by ovarian function.Methodology/Principal FindingsIn this study, the miRNA transcriptomes of ovaries from laying and broody geese were profiled using Solexa deep sequencing and bioinformatics was used to determine differential expression of the miRNAs. As a result, 11,350,396 and 9,890,887 clean reads were obtained in laying and broodiness goose, respectively, and 1,328 conserved known miRNAs and 22 novel potential miRNA candidates were identified. A total of 353 conserved microRNAs were significantly differentially expressed between laying and broody ovaries. Compared with miRNA expression in the laying ovary, 127 miRNAs were up-regulated and 126 miRNAs were down-regulated in the ovary of broody birds. A subset of the differentially expressed miRNAs (G-miR-320, G-miR-202, G-miR-146, and G-miR-143*) were validated using real-time quantitative PCR. In addition, 130,458 annotated mRNA transcripts were identified as putative target genes. Gene ontology annotation and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis suggested that the differentially expressed miRNAs are involved in ovarian function, including hormone secretion, reproduction processes and so on.ConclusionsThe present study provides the first global miRNA transcriptome data in A. cygnoides and identifies novel and known miRNAs that are differentially expressed between the ovaries of laying and broody geese. These findings contribute to our understanding of the functional involvement of miRNAs in the broody period of goose.

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Materials and methods Ethics statementAll procedures involving the care and use of animals conformed to US National Institutes of Health guidelines Abstract: Ferritin, heavy polypeptide 1 (FTH1) is a kind of ferritin complex that catalyzes the conversion of Fe(II) into Fe(III) to protect the cell from oxidative damage. Recent research has shown that FTH1 is also associated with several disease-related processes, such as inflammation and tumor progression and so on. In this study, the coding sequence (CDS) of FTH1 in Jinding ducks was cloned. The CDS sequence revealed an open reading frame of 546 nucleotides encoding a protein with 181 amino acids. Based on this sequence, the duck FTH1 protein is predicted to have conserved domains typical of eukaryotic ferritin. Only one synonymous mutation (c.447T > C) of the coding sequence of the duck FTH1 gene was identified in ducks. Quantitative RT-PCR results revealed that FTH1 expression in the liver and spleen was significantly downregulated after duck hepatitis virus 1 infection. Meanwhile, in DF-1 cells transfected with an FTH1 plasmid, expression of the antiviral marker gene Mx1 was significantly upregulated. These results suggest that the coding sequence of the duck FTH1 gene was highly conserved and FTH1 plays an important role in antivirus activity.

Duck hepatitis virus type 1 (DHV-1) infection of ducklings causes hepatitis and is associated with high morbidity and mortality. Virus infection may induce apoptosis and inhibit proliferation. In humans, ferritin heavy polypeptide 1 (FTH1) has been reported to affect the development of hepatitis and inhibit apoptosis. However, the effect of duck FTH1 (duFTH1) on apoptosis in DHV-1 infected ducklings has not been investigated. Therefore, we measured duFHT1 expression in tissues of DHV-1 infected ducklings and characterized the functional effects of ectopic overexpression and endogenous downregulation of FTH1 in duck embryo fibroblasts (DEF) to elucidate possible mechanisms involved. In the present study, the expression of duFTH1 was decreased in liver and spleen after DHV-1 infection. The effects of altered FTH1 expression on expression of pro- and anti-apoptotic genes were evaluated by qPCR arrays. Decreased expressions of Caspase-3 and Caspase-8 were observed in FTH1-overexpressing DEF cells, while decreased expression of Bcl-2 was detected in FTH1 knocked down DEF cells. Our findings suggest that the regulation of FTH1 expression indirectly mediated the expression of apoptosis-related genes; the protective effect of FTH1 was associated with the inhibition of apoptosis in DEF.