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Browsing by Author "Zhang, Haihan"

Now showing 1 - 4 of 4
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    Cellular Composition and Differentiation Signaling in Chicken Small Intestinal Epithelium
    Zhang, Haihan; Li, Dongfeng; Liu, Lingbin; Xu, Ling; Zhu, Mo; He, Xi; Liu, Yang (MDPI, 2019-10-27)
    The small intestine plays an important role for animals to digest and absorb nutrients. The epithelial lining of the intestine develops from the embryonic endoderm of the embryo. The mature intestinal epithelium is composed of different types of functional epithelial cells that are derived from stem cells, which are located in the crypts. Chickens have been widely used as an animal model for researching vertebrate embryonic development. However, little is known about the molecular basis of development and differentiation within the chicken small intestinal epithelium. This review introduces processes of development and growth in the chicken gut, and compares the cellular characteristics and signaling pathways between chicken and mammals, including Notch and Wnt signaling that control the differentiation in the small intestinal epithelium. There is evidence that the chicken intestinal epithelium has a distinct cellular architecture and proliferation zone compared to mammals. The establishment of an in vitro cell culture model for chickens will provide a novel tool to explore molecular regulation of the chicken intestinal development and differentiation.
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    Ontogeny and biological function of epithelial cells in the chicken yolk sac and small intestine
    Zhang, Haihan (Virginia Tech, 2018-10-11)
    The chicken yolk sac and small intestine are connected through the yolk stalk and share many biological similarities. During the embryonic stage, the extra-embryonic yolk sac helps the embryo to absorb nutrients primarily in the last two weeks of incubation. The chicken yolk sac physically moves yolk contents from the yolk sac to the small intestine at the end of embryogenesis. This is the time when the small intestine replaces the yolk sac in assimilating nutrients for the embryo and later for the posthatch chicken. Additionally, both chicken small intestinal epithelia and the yolk sac secrete beta defensins for promoting intestinal health. Since there are heterogeneous cell types along the mammalian intestinal villus, which are derived from the intestinal stem cells in the crypts, we investigated if cells of the chicken yolk sac and small intestine have the same ontogeny as mammalian intestinal epithelial cells. In this dissertation, we mainly focused on the spatial expression of nutrient transporters (PepT1 and SGLT1), intestinal stem cell markers (Lgr5 and Olfm4), and avian beta defensins in the chicken yolk sac and small intestine during the embryonic and early posthatch stages. RNAscope in situ hybridization was used to identify the distribution of cells expressing PepT1 mRNA in both the chicken yolk sac and small intestine. PepT1 mRNA was found to be expressed by epithelial cells in both the yolk sac and small intestine. In the yolk sac, PepT1 mRNA was uniformly distributed in each endodermal epithelial cell along the villus-like structure. The pattern of PepT1 mRNA expression observed in the chicken yolk sac during the last 10 days of incubation revealed that PepT1 mRNA was increased from e11 to e13, and decreased from e15 to day of hatch. The peak of PepT1 mRNA expression was between e13 and e15, when the yolk sac reaches maximum absorptive area and the growth of the chicken embryo is at its fastest rate. However, the expression of PepT1 mRNA in the intestine was only detected in columnar enterocytes along the villus and not in goblet cells or cells in the crypts. The immunofluorescence assay confirmed that PepT1 protein was located at the brush border membrane of the enterocytes and that protein expression of PepT1 was restricted to the intestinal epithelial cells from approximately the middle to the tip of the villus. In order to identify intestinal stem cells, we used the known mammalian stem cell markers, Lgr5 and Olfm4. Both Lgr5 and Olfm4 are specifically expressed by cells in the chicken intestinal crypts, suggesting that they can be used as biomarkers for chicken intestinal stem cells. Dual labelling of PepT1 and Olfm4 mRNA on the same chicken intestinal sample revealed that there was a gap between PepT1-expressing enterocytes and Olfm4-expressing intestinal stem cells. The cells in this gap were presumably transit amplifying (TA) cells. Additionally, we also found that the TA cell zone along the intestinal villus was reduced during chicken growth. This TA cell population could be clearly detected at day of hatch and d1 posthatch but not later. The expression of SGLT1 mRNA was localized to yolk sac endodermal epithelial cells and showed a sharp increase at the end of incubation. This increase of SGLT1 mRNA coincided with the increase in glucose in the yolk, indicating that the chicken embryo needs glucose as energy for hatching. The mRNA expression profiles of various avian beta defensins have been examined by qPCR and in situ hybridization to investigate the immune function of the yolk sac and small intestine. We found that AvBD10 mRNA showed the highest expression level in the yolk sac and was expressed predominantly in the yolk sac endodermal epithelial cells. Additionally, the expression of AvBD10 mRNA showed a development-specific pattern, which increased from e9 to e11, and decreased from e13 towards day of hatch. The expression patterns of AvBD1, 2, and 7 mRNA were similar to each other. These three genes were found to be expressed by chicken heterophils distributed in the yolk sac blood islands and small intestinal blood vessels. Only a subset of heterophils, which might be activated, were able to express AvBD1, 2, and 7 mRNA. In the intestine, the expression of AvBD10 mRNA was localized to cells along the villus at e19 and day of hatch, but later to only a few cells located above the intestinal crypts. In summary, the endodermal epithelial cells are responsible for the absorptive and immune functions of the chicken yolk sac. The yolk sac mesoderm is critical for embryonic hematopoiesis and innate immunity. The chicken small intestinal epithelial cells are derived from the intestinal stem cells in the crypts. These epithelial cells have different cell types, which are functioning to absorb nutrients and secrete antimicrobial peptides.
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    Polymorphisms in the Chicken Growth Differentiation Factor 9 Gene Associated with Reproductive Traits
    Liu, Lingbin; Cui, Zhifu; Xiao, Qihai; Zhang, Haihan; Zhao, Xiaoling; Wang, Yan; Yin, Huadong; Li, Diyan; Zhu, Qing (Hindawi, 2018-09-19)
    The aim of the study was to investigate GDF9 gene polymorphisms and their association with reproductive traits in chicken using DNA sequencing. A total of 279 Dongxiang blue-shelled (DX) chickens and 232 Luhua (LH) chickens were used for validation. We detected 15 single nucleotide polymorphisms (SNPs): nine SNPs were previously unreported in chicken, two were missense mutations, and only three exhibited significant associations with reproductive traits. G.17156387C>T was significantly associated with age at first egg (AFE) and weight of first egg (WFE) in both breeds. Birds carrying the CC genotype exhibited higher AFE and WFE values than those with the TT genotype. The SNP g.17156427A>G exhibited an association with egg weight at 300 days of age (EWTA) in DX but not in LH chickens. The SNP g.17156703A>C affected the AFE and EN (total number of eggs at 300 days of age) in DX chickens. In addition, certain diplotypes significantly affected AFE, BWTA (body weight at 300 days of age), and EN in both breeds. RT-PCR results showed that the GDF9 gene was highly expressed in stroma with cortical follicles (STR) and prehierarchal follicles. These results provided further evidence that the GDF9 gene is involved in determining reproductive traits in chicken.
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    Whole-transcriptome analysis of atrophic ovaries in broody chickens reveals regulatory pathways associated with proliferation and apoptosis
    Liu, Lingbin; Xiao, Qihai; Gilbert, Elizabeth R.; Cui, Zhifu; Zhao, Xiaoling; Wang, Yan; Yin, Huadong; Li, Diyan; Zhang, Haihan; Zhu, Qing (Springer Nature, 2018-05-08)
    Broodiness in laying hens results in atrophy of the ovary and consequently decreases productivity. However, the regulatory mechanisms that drive ovary development remain elusive. Thus, we collected atrophic ovaries (AO) from 380-day-old broody chickens (BC) and normal ovaries (NO) from evenaged egg-laying hens (EH) for RNA sequencing. We identified 3,480 protein-coding transcripts that were differentially expressed (DE), including 1,719 that were down-regulated and 1,761 that were up-regulated in AO. There were 959 lncRNA transcripts that were DE, including 56 that were downregulated and 903 that were up-regulated. Among the116 miRNAs that were DE, 79 were downregulated and 37 were up-regulated in AO. Numerous DE protein-coding transcripts and target genes for miRNAs/lncRNAs were significantly enriched in reproductive processes, cell proliferation, and apoptosis pathways. A miRNA-intersection gene-pathway network was constructed by considering target relationships and correlation of the expression levels between ovary development-related genes and miRNAs. We also constructed a competing endogenous RNA (ceRNA) network by integrating competing relationships between protein-coding genes and lncRNA transcripts, and identified several lncRNA transcripts predicted to regulate the CASP6, CYP1B1, GADD45, MMP2, and SMAS2 genes. In conclusion, we discovered protein-coding genes, miRNAs, and lncRNA transcripts that are candidate regulators of ovary development in broody chickens.