Bovine Placental Lactogen Research Articles

Chemotactic behavior of Campylobacter fetus subspecies towards cervical mucus, bovine placenta and selected substances and ion.

The chemotaxis of C. fetus subsp. venerealis and C. fetus subsp. fetus was determined in the presence of bovine cervical mucus and bovine placental extract. Some reported substances and ion in those materials, such amino acids, ferrous iron, hormones, sugars and organic acids were also investigated. Bovine cervical mucus, bovine placenta extracts and some substances and ion of these materials namely L–fucose, L– aspartate, L–glutamate, L–serine, ferrous iron, fumarate, pyruvate and succinate were chemoattractants. The chemottraction was significantly larger in higher concentrations of the tested substances and ion and significant differences among tested strains were also observed. Meso-erythritol and hormones bovine placental lactogen, 17β-estradiol, and progesterone did not elicit chemotactical response. In conclusion, this chemotactic behavior may guide the C. fetus navigation in the bovine host's genital tract and be an important cofactor of tissue tropism for this bacterium.

Adiponectin Promotes Maternal β-Cell Expansion Through Placental Lactogen Expression.

Hypoadiponectinemia is a risk factor of gestational diabetes mellitus (GDM). Our previous study reported that adiponectin gene knockout mice (Adipoq -/- ) develop GDM due to insulin insufficiency. The main objective of this study was to elucidate the underlying mechanism through which adiponectin controls islet expansion during pregnancy. A significant reduction in β-cell proliferation rates, β-cell areas, and blood insulin concentrations was detected in Adipoq -/- mice at midpregnancy. Surprisingly, conditionally knocking down adiponectin receptor 1 (AdipoR1) or AdipoR2 genes in β-cells during pregnancy did not reduce β-cell proliferation rates or blood insulin concentrations. In vitro adiponectin treatment also failed to show any effect on β-cell proliferation of isolated pancreatic islets. It was reported that placental lactogen (PL) plays a crucial role in pregnancy-induced maternal β-cell proliferation. A significant decrease in phosphorylation of signal transducer and activator of transcription 5, a downstream molecule of PL signaling, was observed in islets from Adipoq -/- dams. The mRNA levels of mouse PL genes were robustly decreased in the placentas of Adipoq -/- dams. In contrast, adiponectin treatment increased PL expression in human placenta explants and JEG3 trophoblast cells. Most importantly, bovine PL injection restored β-cell proliferation and blood insulin concentrations in Adipoq -/- dams. Together, these results demonstrate that adiponectin plays a vital role in pregnancy-induced β-cell proliferation by promoting PL expression in trophoblast cells.

Placentation and hormonal maintenance of pregnancy in the impala (Aepyceros melampus)

IntroductionThe impala is a widely distributed African ungulate. Detailed studies of the placenta and ovaries in impala undertaken in the 1970s did not address the endocrine functions of the placenta. MethodsThe uteri of 25 pregnant impala estimated to be between 49 and 113 days of the 190 day gestation were examined grossly, histologically and immunohistochemically. ResultsA single corpus luteum was present in either maternal ovary but the conceptus was always situated in the right uterine horn. The fetal membranes extended to the tips of both uterine horns. The amnion was in intimate contact with, but not fused to, the allantochorion. Placentation was typically ruminant with fetal macrocotyledons attached to the rows of maternal caruncles. The fetal villi were highly branched, especially in the centre of each placentome where the attenuated maternal epithelium lining the placental crypts was absent in some places. Both the corpus luteum and the uninucleate trophoblast cells of the interplacentomal allantochorion stained strongly for 3-β hydroxysteroid dehydrogenase, and progestagen concentrations in allantoic and amniotic fluids increased significantly as gestation progressed, with a tendency to do likewise in maternal serum. Binucleate trophoblast cells stained positively for bovine placental lactogen, but neither the placenta nor the maternal corpus luteum showed evidence of oestrogen synthesis. DiscussionDespite exhibiting the same basic type of placentation, both the gross and histological structure of the impala placenta, along with its immunohistochemical properties, demonstrates that great variation exists across ruminant placentas.

Placentation in the Blue Wildebeest (Connochaetes taurinus)

IntroductionThe wildebeest is a populous African ungulate, but despite its wide distribution within that continent few reports exist on the structure and endocrine functions of its placenta. MethodsThe pregnant uteri of 43 Blue Wildebeest estimated to be at less than 70 days of the 8 month gestation period were examined grossly and histologically. Results and discussionThe cervix divided into left and right components which eliminated any connection between the uterine horns and limited conceptus development and placentation to the single ipsilateral horn. The placenta was typically ruminant synepitheliochorial macrocotyledonary with numerous flat placentomes developing in the gravid horn. Appreciable quantities of exocrine secretion were accumulated in the lumen of both gravid and non-gravid uterine horns and proliferation of the trophoblast into presumptive villi was evident between the placentomes. The single corpus luteum of pregnancy persisted unchanged during the period of gestation monitored and the mononuclear trophoblast cells of the intercotyledonary, but not the cotyledonary, allantochorion stained strongly for 3-β hydroxysteroid dehydrogenase indicating their likely secretion of progesterone. The binucleate trophoblast cells stained positively with antisera raised against placenta-associated glycoprotein and bovine placental lactogen. Neither the maternal corpus luteum or the allantochorion showed immunohistochemical staining for cytochrome P450 aromatase.

The growth hormone/prolactin gene family in ruminant placentae

Ruminant placentae produce at least two distinct subclasses of the growth hormone/prolactin gene family, the placental lactogens and prolactin-related proteins. Placental lactogens have been purified from cattle, goat and sheep placentae, and the amino acid sequences of bovine and ovine placental lactogen are known. Bovine and ovine placental lactogens are structurally more similar to prolactin than they are to growth hormone. In addition, six unique mRNAs have been described in cattle that encode prolactin-related proteins that are structurally distinct from ruminant placental lactogens. All characterized ruminant placental lactogens and prolactin-related proteins are products of chorionic binucleate cells, but specific biological functions of these placental hormones have not been elucidated. Ovine placental lactogen may modify maternal and fetal intermediary metabolism to provide energy substrates to the fetus. Bovine placental lactogen has been implicated as a luteotropic agent, and is also capable of stimulating mammogenesis and lactogenesis. No ruminant placental lactogen receptor has been structurally characterized, although they are presumed to be similar to either the growth hormone or prolactin receptor. Available technologies will allow many of the questions regarding the regulation, mechanism of action and function of these placental hormones to be addressed.

Paraoxonase activity in the serum of peripartum dairy cows with different placental lactogen concentrations

The action of the bovine placental lactogen (bPL) hormone on maternal metabolism is still poorly known. Some markers, such as the acute phase protein paraoxonase (PON1), are used as indicators of liver function and help to determine the metabolic condition during the transition period in dairy cows. The aim of this study was to evaluate the activity of paraoxonase (PON1) in the serum of peripartum dairy cows with different levels of bPL. Based on the plasma bPL concentration, 18 cows were divided equally into three groups: LOW ( < 2,68 ng bPL mL-1), MEDIUM (2,68–2,80 ng bPL mL-1), and HIGH ( > 2,80 ng bPL mL-1). The experiment was conducted between 21 days prepartum and 28 days postpartum. Serum samples were collected during the experiment for the determination of bPL concentrations and PON1 activity. The bPL concentration was significantly different between the experimental groups (P ? 0,0001) and the days of serum collection (P ? 0,0001). In the prepartum dairy cows, the PON1 levels were different between the groups (P ? 0,05) and the days of serum collection (P ? 0,05). Cows with high bPL concentration had lower serum PON1 activity (P ? 0,05), while cows with low hormone levels had higher enzyme activity (P ? 0,05). In the postpartum period, there was a significant difference between the days of serum collection (P ? 0,0001) and the interaction between groups and collections (P ? 0,01). The group with high concentrations of bPL had lower levels of PON1 (P ? 0,01), while the group with low bPL maintained higher concentrations of PON1 (P ? 0,01). It was concluded that the cows with higher concentrations of bPL in the prepartum period present a reduction in the serum activity of the PON1 enzyme during the peripartum period.

Bovine placental lactogen is cleaved by matrix metalloproteinases and resulted 25k N-terminal fragments inhibit the proliferation of vascular endothelial cells

Bovine placental lactogen is cleaved by matrix metalloproteinases and resulted 25k N-terminal fragments inhibit the proliferation of vascular endothelial cells

Biology of the Placental Proteins in Domestic Ruminants: Expression, Proposed Roles and Practical Applications

The placenta, a lodgment at the feto-maternal interface, is a temporal organ that plays crucial roles in maintaining gestation and fetal development. To achieve these purposes, the placenta produces an array of proteins with distinct spatio-temporal characteristics. In this review, the authors focus on the paralog families of prolactin (PRL) and aspartic proteinase, exclusively produced by the placenta, and discuss their biological roles and practical significance in animal husbandry. The bovine placental PRL family consists of one classical member and at least ten non-classical members. Bovine placental lactogen (PL) is a unique classical member due to its lactogenic activity and potentially involved in partitioning nutrients to maintain fetal development. In contrast, the biological roles of non-classical members in bovine placental PRL family proteins remain unclear. Recent papers have reported that a non-classical member protein named prolactin-related protein -I (PRP-I) exhibited angiogenic activity following C-terminal cleavage by proteolytic enzymes. These results suggest that non-classical members of the placental PRL family exert their biological activities via specific mechanisms other than the PRL receptor-signaling pathway. The bovine genome contains a hundred or more aspartic proteinase-like genes and at least 22 mRNAs with close structural relationships are transcribed in the placenta. These molecules correspond to pregnancy-specific protein (PSP)-B, PSP-60 and pregnancy-associated glycoprotein (PAG) as reported previously. The true character of PSPs and PAG is thought to be a mixture of placental aspartic proteinase-like proteins. Immunological detection of PAG protein in maternal serum is the basis for early pregnancy diagnosis in ruminants. Currently, early pregnancy diagnosis by PAG assay is available for cows, buffaloes and deer.

Altered secretion of pregnancy-associated glycoproteins during gestation in bovine somatic clones

Somatic nuclear transfer (NT) in cattle is often accompanied by severe placental anomalies, hypertrophy, and hydrallantois, which induce a high rate of pregnancy losses throughout gestation. These placental deficits are associated with an abnormal increase of the maternal plasma levels of pregnancy-associated glycoprotein (PAG), produced by the trophoblastic binucleate cells (BNC) of the placenta. The objective of this study was to analyze the origin of the abnormally elevated PAG concentrations in the peripheral circulation of NT recipients during pathological pregnancies. Concentrations of PAG were measured both in maternal blood, in chorionic and cotyledonary tissular extracts from control recipients (after artificial insemination, AI, or in vitro fertilization, IVF) and clone recipients on Day 32, Day 62, and during the third trimester of gestation. Three different radioimmunoassay (RIA) systems were used. One homologous RIA for PSP60, similar to bovine PAG-1 (PAG67kDa), and two heterologous RIA with PAG67kDa as standard and tracer, and antisera anti-caprine PAG (AS#706 and AS#708). Circulating and tissular concentrations of bovine placental lactogen (bPL), a glycoprotein also produced by BNC, were determined by RIA at the same stages. The number of BNC in the placental tissues was determined by cell counting after immunostaining with anti PSP60 antibody on tissue sections from control and NT pregnancies. Maternal plasma PAG concentrations were not different among groups on Day 32, but they were significantly higher in NT than in control pregnancies on Day 62 with all three RIA and during the third trimester with two RIA (RIA-PSP60 and RIA with AS#708). Circulating bPL concentrations were undetectable on Days 32 and 62 and were not different in the third trimester between NT and control pregnancies. Tissular amounts of PAG on total proteins were not different between the two groups at all stages studied. No difference was determined in the percentage of PSP60-positive BNC in placental tissues between controls and NT on Day 62 and during the third trimester of pregnancy. Western blots of tissular extracts from placenta showed no major molecular weight changes of PAG in NT pregnancies compared to controls. No differences in maternal circulation concentrations or tissular content of bPL were observed between control and NT pregnancies. In conclusion, the specific increase of PAG in maternal plasma concentrations during abnormal NT pregnancies do not result from a higher proportion of BNC, or an increased protein expression of PAG and could be due to changes in the composition of terminal glycosylation which result into a clearance decrease of PAG from the circulation.

Effect of exogenous circulating anti-bPL antibodies on bovine placental lactogen measurements in foetal samples

BackgroundThe involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating antibodies are present together with the hormone, the procedure for hormonal measurement becomes considerably complex. The aim of this study was the immunoneutralization of bovine placental lactogen (bPL) concentrations in bovine foetal circulation by direct infusion of rabbit anti-bPL purified immunoglobulins (IgG) via a foetal catheter (in vivo study). The ability of a RIA based on guinea pig anti-bPL antiserum, for the measurement of bPL concentrations in samples containing exogenous rabbit anti-bPL immunoglobulins, was also analyzed in in vitro and in vivo conditions.MethodsSix bovine foetuses were chronic cannulated on the aorta via the medial tarsal artery. Infusion of rabbit anti-bPL IgG was performed during late gestation. Pooled rabbit anti-bPL antisera had a maximal neutralization capacity of 25 μg bPL/mL of immunoglobulin. Interference of rabbit anti-bPL immunoglobulin with radioimmunoassay measurement using guinea pig anti-bPL as primary antibody was first evaluated in vitro. Polyclonal anti-bPL antibodies raised in rabbit were added in foetal sera to produce 100 samples with known antibodies titers (dilutions ranging from 1:2,500 till 1:1,280,000).Result(s)Assessment of the interference of rabbit anti-bPL antibody showed that bPL concentrations were significantly lower (P < 0.05) in samples added with dilutions of rabbit antiserum lower than 1:80,000 (one foetus) or 1:10,000 (four foetuses). It was also shown that the recovery of added bPL (12 ng/mL) was markedly reduced in those samples in which exogenous rabbit anti-bPL were added at dilutions lower than 1:20,000. Concentrations of foetal bPL were determined in samples from cannulated foetuses. In foetuses 1 and 6, bPL concentrations remained almost unchanged (<5 ng/mL) during the whole experimental period. In Foetus 3, bPL concentrations decreased immediately after IgG infusion and thereafter, they increased until parturition.Conclusion(s)The use of a bPL RIA using a guinea pig anti-bPL as primary antiserum allowed for the measurement of bPL concentrations in foetal plasma in presence of rabbit anti-bPL IgG into the foetal circulation. Long-term foetal catheterization allowed for the study of the influence of direct infusion of anti-bPL IgG on peripheral bPL concentrations in bovine foetuses.

Dystocia in 3-year-old beef heifers; Relationship to maternal nutrient intake during early- and mid-gestation, pelvic area and hormonal indicators of placental function

The influence of nutrition during the first and second trimesters of gestation on the occurrence of dystocia was investigated in 3-year-old composite-breed beef heifers. Heifers were allocated according to stratification by weight and genotype to either a high (H/− = 76 MJ metabolisable energy (ME) and 1.4 kg crude protein (CP)), or low (L/− = 62 MJ ME and 0.4 kg CP daily) nutritional treatment on the day of artificial insemination (day 0) to the same Senepol bull. Half of each nutritional group changed to an opposite nutritional group on day 93 of gestation (−/H = 82 MJ ME and 1.4 kg CP; −/L = 63 MJ ME and 0.4 kg CP daily), resulting in four treatment groups: HH ( n = 16); HL ( n = 19); LH ( n = 17); LL ( n = 19). From 180 days until calving all heifers were fed the same diets. Pelvic area measures were taken at heifer selection (−72 days) and at 117 days. Maternal circulating concentrations of estrone sulphate (ES), bovine placental lactogen (bPL), bovine pregnancy associated glycoprotein and progesterone were monitored throughout gestation. Heifers were observed continuously over the calving period and delivery type classified as being either eutocic or dystocic. The occurrence of dystocia was 14.1%. Increased calf birth weight increased the odds of occurrence of dystocia (odds ratio (OR) = 1.40; 95% confidence interval (95% CI) 1.12–1.76; P < 0.01). High diets in the second trimester were associated with heavier calves at birth ( P = 0.01). The mean pelvic area of eutocic heifers on −72 d, tended to be greater compared to that of dystocic heifers ( P = 0.08) such that a 1-cm 2 difference in pelvic area tended to decrease the risk of dystocia (OR = 0.97; 95% CI 0.93–1.01; P = 0.09). Longer gestation length was associated with an increased risk of dystocia ( P = 0.03). ES ( P = 0.04) and bPL ( P = 0.09) at calving were positively associated with the risk of dystocia. In conclusion, the current study demonstrates (a) that pelvic area measurement at selection in 3-year-old Bos indicus × Bos taurus heifers may be useful for identifying heifers at an increased risk of dystocia and (b) increased ES and bPL concentrations at calving are associated with increased risk of dystocia. Pelvic area measurements obtained prior to conception remain valid in their assessment of the relationship between pelvic area and likelihood of dystocia occurring in the event of changing maternal nutrient intake during gestation. This is an important finding given maternal diets high in protein and energy during the second trimester of gestation increased calf birth weight and calf birth weight was associated with an increase in the occurrence of dystocia in heifers calving as 3-year olds.

The characterization of DNA methylation-mediated regulation of bovine placental lactogen and bovine prolactin-related protein-1 genes

BackgroundBovine trophoblast binucleate cells (BNC) express a plethora of molecules including bovine placental lactogen (bPL, gene name is bCSH1) and bovine prolactin-related protein-1 (bPRP1). BCSH1 and bPRP1 are members of the growth hormone (GH)/prolactin (PRL) gene family, which are expressed simultaneously in BNC and are central to placentation and the progression of pregnancy in cattle. However, there is a paucity of information on the transcriptional regulatory mechanisms of both the bCSH1 and bPRP1 genes. Recent studies, however, have demonstrated that the expression of a number of genes is controlled by the methylation status of their promoter region. In the present study, we examined the cell-type-specific epigenetic alterations of the 5'-flanking region of the bCSH1 and bPRP1 genes to gain an insight into their regulatory mechanisms.ResultsAnalysis of 5-aza-2'-deoxycytidine treatment demonstrated that bCSH1 expression is moderately induced in fibroblast cultures but enhanced in BT-1 cells. Sodium bisulfite based sequencing revealed that bCSH1 is hypomethylated in the cotyledonary tissue but not in the fetal skin, and this pattern was not altered with the progression of pregnancy. On the other hand, the methylation status of bPRP1 was similar between the cotyledon and fetal skin. The bPRP1 gene was exclusively hypermethylated in a bovine trophoblast cell-derived BT-1 cell-line. While the activity of bCSH1 was similar in both BT-1 and bovine fibroblast cells, that of bPRP1 was specific to BT-1. Treatment with a demethylating agent and luciferase assays provided in vitro evidence of the positive regulation of bCSH1 but not bPRP1.ConclusionThis is the first report to identify the differential regulatory mechanisms of the bCSH1 and bPRP1 genes and indicates that bCSH1 might potentially be the only transcript that is subject to DNA methyltransferase regulation. The data indicates the possibility of novel kinetics of induction of the synchronously expressed BNC-specific bCSH1 and bPRP1 transcripts, which may aid the understanding of the intricate regulation and specific role(s) of these important molecules in bovine placentogenesis and the progression of pregnancy.

Dietary Protein During Gestation Affects Circulating Indicators of Placental Function and Fetal Development in Heifers

The influences of nutritional protein during the first and second trimesters of pregnancy on placental hormones and fetal growth were determined in composite beef heifers. At artificial insemination, heifers were stratified by weight within each composite genotype into 4 treatment groups: High High (HH=1.4kg crude protein (CP)/day for first and second trimesters of gestation; n=16), High Low (HL=1.4kg CP/day for first trimester and 0.4kg CP/day for second trimester; n=19), Low High (LH=0.4kg CP/day for first trimester and 1.4kg CP/day for second trimester; n=17) or Low Low (LL=0.4kg CP/day for first and second trimesters; n=19). Maternal plasma bovine pregnancy associated glycoprotein (bPAG) and progesterone (P4) were determined at gestation day (gd) 28, 82, 179 and 271 (mean gestation length 286 days) in addition to P4 at term. Estrone sulphate (ES) and bovine placental lactogen (bPL) concentrations were measured at gd 124, 179, 236 and 271 and at term in addition to ES at gd 82. Low dietary protein increased placental function as indicated by increased bPAG (P<0.001) and ES (P=0.02) concentrations in first trimester and increased bPL concentrations (P=0.01) in the second trimester of gestation. In the third trimester, when dietary treatment had ceased, placental function was no longer associated with previous dietary treatments. Dam genotype affected placental function as measured by bPL (P<0.001) and ES concentrations (P=0.02). Calf gender, heifer age and maternal insulin-like growth factor (IGF)-I, -II and leptin did not affect hormonal indicators or circulating markers of placental function. Enhanced placental function during the third trimester, as measured by ES, was associated with increased calf birth weight (P=0.003).

Polymorphism identification, RH mapping and association of placental lactogen gene with milk production traits of dairy cows

Bovine placental lactogen (bPL) is structurally related to prolactin (PRL) and growth hormone (GH). In synergism with steroid and thyroid hormones, bPL is crucial in stimulating the development of the mammary gland, mammary cell differentiation and function. To further explore whether bPL gene is associated with milk production traits, we herein analyzed single-nucleotide polymorphisms (SNPs) within eight regions of bPL gene, which are potentially associated with five milk production traits on 1028 Chinese Holstein cows. Among these, two SNPs, NT7409(T–C) and Nt11246(G–A), were identified. The former is within exon 2; it induces an alteration of amino acid from Val to Ala. The later is within exon 4. It is a synonymous mutation. We found that there were significant associations between NT7409(T–C) and milk and protein yield. Cows of the AA genotype yielded less milk (P = 0.001) and less protein (P = 0.003) than those of genotypes AB and BB. However, on the NT11246(G–A) locus, no significant association was observed in the five milk production traits studied. In addition, bPL has been localized near markers RM185 and CC549051 with a distance of 23.2 cR on BTA 23. It is at the same position as the region including quantitative trait loci (QTLs) affecting milk and protein yields by previous linkage analysis. In summary, our findings demonstrated that the SNP within exon 2 of bPL (NT7409(T–C)) is associated with two milk production traits, and this provided further evidence that bPL could be a major gene-controlling milk production trait in Holstein dairy cattle.

Interactions of the bovine placental lactogen and prolactin receptor genes are associated with fertility traits in cattle

Decline in fertility of high-producing dairy cattle has become a global challenge to the dairy industry. Because of low heritability and complexity, it is difficult to find genetic markers for fertility traits in cattle. Here, we report the use of an in vitro fertilization (IVF) system and candidate gene approach to test genetic associations of a single-nucleotide polymorphism (SNP) in bovine placental lactogen (bPL), and its interactions with SNPs in the prolactin receptor (PRLR) and growth hormone receptor genes with fertility traits in an IVF system. The associations suggest a possible involvement of genetic interactions between bPL and PRLR in the fertilization and embryonic development processes, and the potential for application in a marker-assisted selection program.

Dickkopf-1 Expression During Early Bovine Placentation and Its Down-regulation in Somatic Cell Nuclear Transfer (SCNT) Pregnancies

The precise role of Dickkopf-1 (Dkk-1) during early bovine trophoblast development and subsequent placentation is not fully understood. Using somatic cell nuclear transfer (SCNT) generated pregnancies as a model of poor placentation we have found that mean levels of Dkk-1 mRNA were 1.5 fold lower in SCNT fetal cotyledon tissue at Day 50 of gestation than those resulting from artificial insemination (AI) and 2 fold lower at Days 100 and 150 (P<0.004). Dkk-1 expression in cotyledon tissue was localized by in situ hybridization to fetal binucleate cells (BNCs). Examining conceptuses from blastocyst stage we show that Dkk-1 mRNA was first evident between Days 15-20 of gestation in trophoblast tissue (when BNCs first appear) prior to the initial expression of the BNC specific bovine placental lactogen (bPL) on Day 20. Dkk-1 mRNA levels were higher than bPL in trophoblast tissue throughout the pre-attachment period (Days 24-31), however, this reversed during cotyledon development with only a subset of the bPL immunoreactive BNCs also containing Dkk-1 protein, suggesting a specific role for Dkk-1 during early placentation. One function of Dkk-1 is as an antagonist of the Wnt signaling pathway and, although Wnt5A and Wnt7A mRNAs were expressed in Day 50 bovine cotyledons, their expression levels were similar between AI and SCNT. In addition, the nuclear localization of beta-catenin, which is an indicator of activation of the Wnt pathway, was also similar between AI and SCNT cotyledon tissue. Transcriptional control of Dkk-1 was not due to changes in DNA methylation levels in the promoter region as methylation levels were no different when comparing AI and SCNT tissues. The decreased expression of Dkk-1 in SCNT cotyledons that are prone to abnormal placentation suggests a role in cotyledon formation but the mechanism and regulatory control is yet to be revealed.

105 DETECTION OF PLACENTAL LACTOGENS IN SWAMP BUFFALO BY RADIOIMMUNOASSAY TECHNIQUE

Ruminant placental lactogens (PL) are members of the growth factor/prolactin (GH/PRL) family. They are synthesized by trophectodermal binucleate cells. There is evidence to suggest that PL is involved in control of fetal growth, through actions in both the maternal and fetal compartments, as well as in influencing mammary growth during pregnancy (Byatt JC et al. 1992 J. Anim. Sci. 70, 2911–2923). The structure and biology of PL have been studied in the cow, sheep, goat, human, and mice. The maternal concentration of PL is 100- to 1 000-fold greater in pregnant sheep and goats than in cows but no information exists about PL concentration in buffalo. The aim of the present study was to evaluate the ability to detect PL in buffalo fluids by using bovine PL antibody. Samples were collected in the slaughterhouse immediately after animal slaughter. The fetuses were measured after heart blood collection. A bPL RIA system was used to determine the bPL concentrations in the buffalo samples (Alvarez-Oxiley AV et al. 2007 Reprod. Fertil. Dev. 19, 877–885). The rbPL molecules were radio-iodinated with [125]I-Na by using the lactoperoxidase method (Thorell JI and Johansson BG 1971 Biochim. Biophys. Acta 251, 363–369). Concentrations of buffalo PL are presented in Table 1. In this RIA system, the minimum detected value was 0.068 ng mL–1, and the binding competition curves of bovine PL standard and buffalo fluids dilution using bovine PL antibody were paralleled in all kinds of samples. The lowest concentration was detected in allantoid fluid and the greatest concentration in fetal plasma (P &lt; 0.05). Study of the biology of PL in buffalo has proved difficult because the concentration of PL in all buffalo fluids is very low. Furthermore, the research concerning buffalo PL function required in vivo experiments. Existing data suggest that at least the concentration of buffalo PL is different from cattle and other smaller domestic ruminants. In conclusion, our results provide preliminary information about concentrations of PL in buffalo fluids. Table 1.Concentration of placental lactogen in buffalo fluids This work was supported by a grant from the Belgian Technical Cooperation.

Bovine prolactin-related protein-I is anchored to the extracellular matrix through interactions with type IV collagen

The bovine placenta produces an array of proteins structurally similar to pituitary prolactin (PRL). At least ten genes of the bovine placental PRL family, including bovine placental lactogen (bPL) and ten bovine PRL-related protein-I to -X (bPRP-I to -X), encode hormones/cytokines predicted to be involved in the establishment and maintenance of pregnancy. Targets and biological roles for most members of the bovine PRL family have yet to be specified. This study focused on three members of bovine PRL family, bPL, bPRP-I, and bPRP-VI. An alkaline phosphatase (AP) tagging strategy was used to monitor interactions of the ligands with their targets. AP-bPRP-I and AP-bPRP-VI specifically bound to tissue sections of the bovine placentome. AP-bPRP-I and AP-bPRP-VI binding within the placentome mimicked the distribution of the extracellular matrix (ECM). Consequently, AP fusion protein binding to individual ECM components (heparin, laminin, fibronectin, type I collagen, and type IV collagen) was evaluated. AP-bPRP-I specifically bound to type IV collagen, but not to the other ECM components. AP-bPRP-VI exhibited weak interactions with ECM components, while AP-bPL and AP did not show significant binding to any of the ECM components. Binding of AP-bPRP-I to type IV collagen was concentration-dependent, influenced by salt concentrations, and specific to the N-terminal cross-linking domain (7S) of type IV collagen but not its triple-helical domain. The interaction of bPRP-I with type IV collagen suggests that bPRP-I accumulates in the ECM where it likely acts on cells traversing the bovine placentome.

Les glycoprotéines placentaires chez les mammifères

Placental tissue exhibits a typical glycosylation pattern, which differs from that observed in the pituitary gland. Depending to the species and pregnancy period, the placenta synthesizes diverse glycoproteins, some of which have significant hormonal activity, others being detected in maternal circulation. Thus, these molecules are of interest both from a fundamental and clinical point of view. Among the mammalian placental glycoproteins currently recognized, chorionic gonadotrophins from primates and Equidae, placental lactogen from bovines and the pregnancy-associated glycoproteins from ruminant species are particularly noteworthy. The diversity of saccharidic structures leads to multiple forms of placental glycoproteins exhibiting distinct structural and biological properties. For instance, concerning the chorionic gonadotrophins, the association of both alpha and beta subunits is essential for the binding of the hormone to specific receptors. Moreover, the N-linked oligossacharides are required for the activation of effectors systems. Bovine placental lactogen is a glycosylated hormone, exhibiting somatotropin- and prolactin-like activities. Several N-glycosylation sites confer to pregnancy-associated glycoproteins a long half-life (8–10 days) in maternal circulation. Assay of these molecules can be used for routine early pregnancy diagnosis and the follow-up of embryonic and fetal mortalities.

A Light and Electron Microscopical Study of the Tragulid (Mouse Deer) Placenta

The Tragulidae are the living relics of the basal ruminant stock. They have a diffuse placenta, with no aggregations of the placental villi into localised placentomes characteristic of all other ruminants. Despite this difference, this ultrastructural and immunocytochemical investigation demonstrates that in Tragulus the trophoblast binucleate cell (BNC) plays the same central role in development and structure as in all other ruminants. It shows an identical development and ultrastructure, produces granules reactive with bovine placental lactogen and pregnancy associated glycoprotein antibodies, and migrates when mature through the trophoblast tight junction to fuse into a mosaic of syncytial plaques from which the granules are released to the mother and which have replaced the uterine epithelium. Unlike the persistent plaques in the sheep and goat placenta, in Tragulus they are transient, dying by apoptosis with the fragments phagocytosed by the trophoblast. This brings the trophoblast into direct endotheliochorial apposition to maternal tissue until BNC migration and fusion replace the dead plaque. This intimate fetomaternal confrontation has not been shown in any other ruminant, and could be a relic of the evolutionary development of the synepitheliochorial from the original basic eutherian endo- or hemo-chorial placenta.