Cellular localisation of the pregnancy-associated glycoprotein family (PAGs) in the synepitheliochorial placenta of the European bison

Evaluation of a cattle rapid test for early pregnancy diagnosis in sheep

The early pregnancy diagnosis allows optimizing production and timely management correction, with a greater reproductive output of livestock. The Idexx Rapid Visual Pregnancy Test® consists of an ELISA for visual reading which does not require the use of readers in the laboratory, with satisfactory pregnancy diagnoses at 28 days of pregnancy in cattle. Therefore, the aim of this study was to evaluate this rapid test and to verify the most appropriate day for the diagnosis of pregnancy in the ovine species. For this purpose, 98 serum samples from pregnant sheep and 36 from non-pregnant were used, with duplicate samples, and diagnosis was confirmed by ultrasound examination, used as the gold standard. The numbers of positive samples obtained at 26, 28, and 30 days of pregnancy were 26, 27, and 45, respectively. The Rapid Visual Pregnancy Test correctly identified 100% of the samples as positive at pregnancy of days 26, 28, and 30. The sensitivity and specificity of the test were also 100%. The Idexx Rapid Visual Pregnancy Test, initially indicated for cattle, is effective for the detection of pregnancy in the ovine species, enabling diagnosis of pregnant sheep from the 26th day of pregnancy.

Identification of pregnancy-associated glycoprotein family (PAG) in the brown bear (Ursus arctos L.)

Pregnancy-associated glycoproteins (PAGs) are abundant embryo-originated products expressed in the pre-placental trophoblast and, later, in the post-implantational chorionic epithelium of some mammalian species. This paper describes the identification and cellular immunolocalization of the chorionic PAG family in the discoidal-type placenta of the brown bear (Ursus arctos L. - Ua), in which the PAGs were named 'UaPAG-Ls'. The study used: 1) Western blot for total placental glycoproteins; and 2) cross-species heterologous double fluorescent immunohistochemistry (IHC) for cellular immune-localization of the PAGs. This is the first study reporting the identification and immunolocalization of the UaPAG-L family in placental cells during early pregnancy in the brown bear. Our Western analysis revealed a dominant mature 72 kDa UaPAG-L isoform was expressed in all Ua placentas during early pregnancy. Various other UaPAG-L isoforms (16-66 kDa) were also identified. Using IHC, the UaPAG-L proteins were localized to trophectodermal cells (TRD), where signal intensity resembled intense TRD proliferation within developing placenta. The data increases our general knowledge of PAG proteins localized in discoidal-type placenta during early pregnancy in the brown bear.

Identification of Placental Aspartic Proteinase in the Eurasian Beaver (Castor fiber L.)

Aspartic proteinases (AP) form a multigenic group widely distributed in various organisms and includes pepsins (pep), cathepsins D and E, pregnancy associated glycoproteins (PAGs) as well as plant, fungal, and retroviral proteinases. This study describes the transcript identification and expression localization of the AP within the discoid placenta of the Castor fiber. We identified 1257 bp of the AP cDNA sequence, encoding 391 amino acids (aa) of the polypeptide precursor composed of 16 aa signal peptide, 46 aa pro-piece, and 329 aa of the mature protein. Within the AP precursor, one site of potential N-glycosylation (NPS^119–121) and two Asp residues (D) specific for the catalytic cleft of AP were identified (VLFDTGSSNLWV^91–102 and GIVDTGTSLLTV^277–288). The highest homology of the identified placental AP nucleotide and aa sequence was to mouse pepsinogen C (75.8% and 70.1%, respectively). Identified AP also shared high homology with other superfamily members: PAGs, cathepsins, and napsins. The AP identified in this study was named as pepsinogen/PAG-Like (pep/PAG-L). Diversified pep/PAG-L protein profiles with a dominant 58 kDa isoform were identified. Immune reactive signals of the pep/PAG-L were localized within the trophectodermal cells of the beaver placenta. This is the first report describing the placental AP (pep/PAG-L) in the C. fiber.

Identification of Novel Placentally Expressed Aspartic Proteinase in Humans

This study presents pioneering data concerning the human pregnancy-associated glycoprotein-Like family, identified in the genome, of the term placental transcriptome and proteome. RNA-seq allowed the identification of 1364 bp hPAG-L/pep cDNA with at least 56.5% homology with other aspartic proteinases (APs). In silico analyses revealed 388 amino acids (aa) of full-length hPAG-L polypeptide precursor, with 15 aa-signal peptide, 47 aa-blocking peptide and 326 aa-mature protein, and two Asp residues (D), specific for a catalytic cleft of the APs (VVFDTGSSNLWV91-102 and AIVDTGTSLLTG274-285). Capillary sequencing identified 9330 bp of the hPAG-L gene (Gen Bank Acc. No. KX533473), composed of nine exons and eight introns. Heterologous Western blotting revealed the presence of one dominant 60 kDa isoform of the hPAG-L amongst cellular placental proteins. Detection with anti-pPAG-P and anti-Rec pPAG2 polyclonals allowed identification of the hPAG-L proteins located within regions of chorionic villi, especially within the syncytiotrophoblast of term singleton placentas. Our novel data extend the present knowledge about the human genome, as well as placental transcriptome and proteome during term pregnancy. Presumably, this may contribute to establishing a new diagnostic tool for examination of some disturbances during human pregnancy, as well as growing interest from both scientific and clinical perspectives.

Expression of pregnancy-associated glycoprotein family in the epitheliochorial placenta of two Camelidae species (C. dromedarius and C. bactrianus)

This study describes placental morphology and immunolocalization of the placental pregnancy associated glycoprotein-like family (PAGs) identified in two selected taxa of Old-World camels of the Camelidae family: Camelus dromedarius (Cd) and Camelus bactrianus (Cb). Placental tissues of Cd from days 140-293 post-coitum (dpc), term (404 dpc); and of Cb from term (440 dpc) were examined. Histological staining (hematoxylin/eosin and propidium iodine) revealed the development of the placental structure, while chorionic folding increased the feto-placental surface during the progress of pregnancy. The camelid placenta during early pregnancy is similar to the diffuse epitheliochorial type, and during later stages of pregnancy resembles the synepitheliochorial (cotyledonary) type. Placental expression of the PAGs was detected (Alexa 488 - green) within camelid trophectoderm cells (TRD - chorionic epithelium as outer layer of embryonic cells) among all placental cells with nuclei stained by propidium iodide (red). The PAGs, identified in both Camelidae taxa, were named CbPAGs and CdPAGs. Placental CbPAG and CdPAG expression is restricted to the TRD cells, which are differentially developed throughout gestation. Cross-reactivity of polyvalent anti-pPAG polyclonals with the CbPAGs and CdPAGs revealed high structural similarities of the PAG-like epitopes in pigs and camels. This is the first study identifying PAG expression in chorionic cells of the camel placenta.

Pregnancy-associated glycoprotein (PAG) family localized in chorionic cells within the epitheliochorial/diffuse placenta of the alpaca (Lama pacos)

Pregnancy-associated glycoproteins (PAGs) are abundant embryo-originated products expressed in the pre-placental trophoblast and later in the post-implantational chorionic epithelium of some ungulate species. This paper describes the cellular immunolocalization of the chorionic PAG family in the epitheliochorial placenta type of the alpaca (Lama pacos-Lp), in which the PAGs were named 'LpPAGs'. Placental Lp sections (5 μm) of different females near mid-pregnancy (150 days post coitum; dpc), advanced pregnancy (244-263 dpc) and late pregnancy (347 dpc) were used for cross-species (heterologous-ht) double fluorescent immunohistochemistry (htdF-IHC). The htdF-IHC was performed with primary rabbit polyvalent anti-porcine PAG polyclonals. The LpPAG immuno-complexes were visualized with secondary goat anti-rabbit immunoglobulins-conjugated with Alexa 488 fluorophore (green), among all nuclei of placental cells stained with propidium iodide (red). This is the first study reporting the immunolocalization of the LpPAG family identified by htdF-IHC at the feto/maternal interface during different pregnancy stages of the alpaca. The most dominant and strongest immune-positive LpPAG signals were found in the well-developed chorionic cell layer. Our htdF-IHC indicated relatively high epitope resemblance to that of the PAGs in camelids and pigs. These data increase our general knowledge of chorionic PAG localization during pregnancy-stage dependent development of the epitheliochorial diffuse placenta type in the alpaca.

Pregnancy-associated glycoprotein (PAG) family: transcripts and gene amplicons in camelids

In this study, the placental localization of PAG-like transcripts and genomic existence of PAG-like amplicons in new-world (Lp, Lama pacos, alpaca) and old-world camelids (Cb, Camelus bactrianus, bactrian; Cd, Camelus dromedarius; dromedary) are reported for the first time. Sections of Lp (150-347 days post coitum), Cd (43-90 cm crown-rump length) and Cb (term) placentas were used for heterologous (ht; cross-species) autoradiographic in situ hybridization (aISH) with single-stranded diagnostic (antisense) or control (sense) [alpha-(35)S]dATP-labeled 323 nt porcine PAG8 (pPAG8) cDNA probes produced by asymmetric PCRs. The aISH with antisense (35)S-pPAG8 probe identified camelid PAG-like (LpPAG, CbPAG and CdPAG) mRNA expression restricted to chorionic epithelium cells within placentas of camelids. In addition, genomic DNA (gDNA), isolated from placental sections were used as templates for camelid PAG-like gene amplicon production by PCR. Specificity of the obtained multiple camelid gDNA PAG-like amplicons was confirmed by double ht-Southern hybridizations with [alpha-(32)P]dATP-labeled 611 bp pPAG5 and pPAG10 double-stranded cDNA probes. The double ht-Southern hybridizations of camelid gDNA amplicons (with pPAG5 and -10 probes) allowed the identification of length-polymorphism of LpPAG, CbPAG and CdPAG genes, coding catalytically active and potentially inactive forms. Such an application of porcine PAG probes may be advantageous for future identification of still undiscovered PAG-like families in other eutherian species.