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α‐1,3‐Galactosyltransferase (α‐GalT), an enzyme creating Galα1‐3Gal (α‐Gal) epitope on the cell surface in some mammalian species such as pigs, is known to be a key factor that causes hyperacute rejection upon transplantation from pigs to humans. To establish the RNA interference‐based suppression of endogenous α‐GalT messenger RNA (mRNA) synthesis in porcine preimplantation embryos, we determined the suitable embryonic stage at which stage such approach is possible by using the semi‐quantitative RT‐PCR (qRT‐PCR) and the cytochemical method using a fluorescence‐labeled Bandeiraea simplicifolia Isolectin B4 (BS‐I‐B4). Staining with BS‐I‐B4 demonstrated that α‐Gal epitope expression was first recognized at the 8‐cell stage, and increased up to the hatched blastocyst stage. Single embryo‐based qRT‐PCR also confirmed this pattern. These results indicate that creation of α‐Gal epitope is proceeded by de novo synthesis of α‐GalT mRNA in porcine preimplantation embryos with peaking at the blastocyst stage.  相似文献   

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Canine Merkel cell tumours are rare neuroendocrine neoplasms that show a relatively benign biological behaviour when compared with their human counterparts. To date, little information is available on their immunohistochemical properties. This report describes the histopathological and immunohistochemical features of two such tumours. The tumours’ immunoreactivity profile was studied with respect to different cellular molecules including chromogranin A (CGA), neurone‐specific enolase (NSE), S100 protein, c‐KIT, the cytokeratins (CKs) detected by pancytokeratin (AE1/AE3) antibodies (i.e. high molecular weight CKs 1, 2, 3, 4, 5, 6, 10, 14, 15 and 16, and low molecular weight CKs 7, 8 and 19) and three markers proposed to correlate with increased malignancy in human tumours: E‐cadherin, β‐catenin and p63 protein. In both lesions, tumour cells were positive for cytokeratins, CGA, NSE, S100 and c‐KIT. No immunostaining was observed for p63 protein, and there was no loss or change in E‐cadherin or β‐catenin immunoexpression. These results suggest that the generally benign behaviour of canine Merkel cell tumours, when compared with their human counterparts, may be partly explained by the conservation of important intercellular adhesion molecules such as E‐cadherin and β‐catenin. Additionally, expression of S100 but not of the p63 protein suggests that these canine tumours present a trend towards neural, rather than basal, epithelial differentiation and do not readily compare with human Merkel cell tumours.  相似文献   

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