Changes in the intracellular accumulation and distribution of metallothionein in rat liver and kidney during postnatal development

Metallothionein (MT) bound to zinc and copper was detected in high concentration in fetal and newborn rat livers by a cadmium saturation method. The levels of both hepatic zinc and MT remained high for the first 14 days after birth and decreased to adult levels by 24 days of age. There was a direct linear relationship between hepatic metallothionein and zinc concentrations during the first 31 days after birth. The ratio of MT to zinc levels also decreased with age suggesting a rapid degradation of MT during postnatal development. Immunohistochemical localization of MT by peroxidase-antiperoxidase technique, using a specific antibody to MT, showed intense intranuclear staining for MT in fetal and newborn rat liver which persisted until Day 9. The nuclear MT staining decreased with age; at 11 days it was equal both in nucleus and cytoplasm and at 14 days, MT was localized mainly in the cytoplasm, similar to adult rat liver pattern. The intranuclear localization of MT in neonates could be considered as a typical fetal-neonatal morphological pattern and its subsequent presence in the cytoplasm, an adult pattern.     

Fetuin: an acute phase protein in cattle

Summary Fetuin is a plasma protein present in high concentrations during fetal development in animals of the order Artiodactyla. Its role is not known. The human homologue of fetuin — ₂HS glycoprotein — has been shown to be a negative acute phase protein in adult plasma. In the present study, the concentration of fetuin was measured in the serum of healthy cattle (Bovis bovis) and in animals with various injuries and inflammatory disorders. The levels were decreased by 30% in pregnancy but increased up to 10-fold in some trauma cases. A significant negative correlation between the concentrations of fetuin and albumin has also been found. Thus, fetuin appears to be a positive acute phase protein in cattle.Abbreviations ₂HS ₂HS glycoprotein - AP acute phase     

Detection of male and female fetal DNA in maternal plasma by multiplex fluorescent polymerase chain reaction amplification of short tandem repeats

The purpose of this study was to develop a fluorescent polymerase chain reaction (PCR) assay for the detection of circulating fetal DNA in maternal plasma. Maternal DNA extracted from plasma samples of pregnant women at term and newborn DNA isolated from cord blood were used to genotype 12 mother/child pairs at nine different polymorphic short tandem repeat loci. Multiplex fluorescent PCR was used to detect fetus-specific alleles in the corresponding maternal plasma samples. Fetus-specific alleles were found in all maternal plasma samples studied. Using these polymorphic repeat sequences, every mother/child pair was informative in at least four of nine loci. Paternally inherited fetal alleles were detected in 84% of informative short tandem repeats. This approach may have implications for non-invasive prenatal diagnosis. Compared with other fetal DNA detection systems that use fetus-derived Y sequences to detect only male fetal DNA in maternal plasma, our proposed technique can be applied to both female and male fetuses.     

Fetuin: the bovine homologue of human alpha 2HS glycoprotein

The fetal protein fetuin has previously been considered to be confined to species of the order Artiodactyla (cattle, sheep, etc.) in spite of demonstrable biological in vitro effects in tissues of other species [(1983) Comp. Biochem. Physiol. 76A, 241-245]. We have determined the partial amino acid sequence of bovine fetuin and compared it with the published sequence of human alpha 2HS glycoprotein. The N-terminal 105 residues and a segment aligned with residues 170-225 of alpha 2HS glycoprotein revealed 109 of 161 residues to be identical between the two proteins (68% homology). Mouse polyclonal antibodies to fetuin, and trypsin digest fragments of this protein have been prepared and used for a comparison of native and digested proteins. Polyclonal antibodies to native protein showed little if any cross reactivity. However, antibodies to trypsin digest fragments of fetuin showed obvious cross reactivity with alpha 2HS.     

The expression of fetuin in the development and maturation of the hemopoietic and immune systems

 The distribution and expression of fetuin, a fetal plasma protein that has been shown to have a widespread intracellular presence in many developing tissues including the central nervous system, has been studied in the developing immune and hemopoietic organs of fetal and adult sheep. The presence of fetuin was demonstrated using immuno-cytochemistry and expression of fetuin was studied using northern blot analysis and in situ hybridization. In the developing sheep fetus, fetuin was shown to be expressed first in the hemopoietic cells of the fetal liver and subsequently in the forming spleen. The very first stromal, bone marrow-forming cells, also expressed fetuin mRNA. These cells became more numerous during gestation and by embryonic day (E)115 (term is 150 days), fetuin-expressing cells were identified morphologically to be monocytes/macrophages. Fetuin protein, on the other hand, was present in all hemopoietic and immune organs from the earliest age studied (E30) but was confined initially to matrix, mesenchymal tissue. Fetuin-positive cells could be identified in the spleen at E60 as early hemopoietic cells, in the lymph nodes at E60 as stromal cells and macrophages, and at E115 in the thymus as macrophages and squamous cells. In the adult, fetuin mRNA was only detectable by northern blot in the liver and the bone marrow. Using in situ hybridization in adult tissue, fetuin mRNA-positive cells were identified in the bone marrow to be monocytes/macrophages. Additionally, in the spleen germinal centres, fetuin mRNA was identified in cells with the morphology of dendritic cells. Using three separate cellular markers: lysozyme, S-100, and α₁-antitrypsin, the cellular identification of fetuin-positive cells was confirmed to be in the monocyte/macrophage lineage. Accepted: 3 May 1996     

Adenylate kinase isoenzyme patterns in normal and neoplastic human lung, and in various adult as compared to fetal rat tissues

The isozyme pattern and total activity of adenylate kinase were studied in normal adult and fetal human and rat tissues using starch gel electrophoresis. Three adenylate kinase isoenzymes were identified in human tissues. Although normal adult lung exhibited higher adenylate kinase activity than did its fetal or neoplastic variant, isozyme patterns in the three types of tissues were indistinguishable from each other and from that in fetal human liver. The pattern of these three isozymes in rat lung (as in spleen) also did not change between fetal and adult life. However, adult kidney and heart of this species did appear to contain isozymes not present in fetal life. Brain (both adult and fetal) was striking different from all the other tissues in that it contained only one adenylate kinase isozyme. The total adenylate kinase activity per gram of adult rat liver, kidney and lung was significantly higher than in the cognate fetal organs, whereas that in brain or spleen did not change with age. The activity in adult heart (similar to the fetal one) was higher than in any other tissue examined.     

The nucleotide and partial amino acid sequences of rat fetuin. Identity with the natural tyrosine kinase inhibitor of the rat insulin receptor.

Fetuins are among the major plasma proteins, yet their biological role has remained elusive. Here we report the molecular cloning of rat fetuin and the sequence analysis of a full-length clone, RF619 of 1456 bp with an open reading frame of 1056 bp encoding 352 amino acid residues. The coding part of RF619 was identical with the cDNA sequence of the natural inhibitor of the insulin receptor tyrosine kinase from rat (pp63) except for four substitutions and a single base insertion causing divergence of the predicted protein sequences. Partial amino acid sequences of rat plasma fetuin were in agreement with the predictions based on the RF619 cDNA. Purified rat fetuin inhibited the insulin receptor tyrosine kinase in vitro. Therefore, we conclude that RF619 and pp63 cDNA encode the same protein, i.e. authentic rat fetuin which is a functional tyrosine kinase inhibitor.     

Marked acceleration of exogenous fatty acid incorporation into cellular triglycerides by fetuin.

Fetuin belongs to a group of fetal glycoproteins whose specific function is not known. In this study we investigated the effect of bovine fetuin on exogenous fatty acid incorporation into lipid classes by fetal rabbit aortic smooth muscle cells (SMC) and human fetal skin fibroblasts. When compared with albumin, the addition of fetuin to the culture medium caused a dramatic increase in labeled fatty acid incorporation (nanomoles/mg of protein) by SMC into triglycerides (albumin (control) 2.8 +/- 0.3 + fetuin 178.3 +/- 13.7). This effect was noted at a wide range of fetuin concentrations (0.2-5%) at oleate:fetuin molar ratios of 3.3-0.13, respectively. Similar effects were noted using human fetal skin fibroblasts with both labeled oleic and arachidonic acids (0.1 mM) as substrates (arachidonic acid incorporation into triglycerides, albumin (control) 76.9 +/- 16.2 + fetuin 684.6 +/- 64.1). Stimulation of fatty acid incorporation into di- and monoglycerides was also noted. Although the amount of unbound fatty acid in the presence of fetuin was greater than with albumin, experiments done under conditions that create identical unbound oleate levels (by varying fatty acid concentration) still showed increased fatty acid incorporation into triglycerides by SMC when exposed to fetuin. This marked effect of fetuin on triglyceride accumulation in cells was confirmed by lipid analysis, strong positive staining with oil red O, and transmission of electron microscopy. Furthermore, the potential physiological role of fetuin in terms of fatty acid and transport was attested by (a) the presence of significant amounts of free fatty acids associated with fetuin; and (b) by the stimulatory effect of fetuin, even when added to culture media containing other fatty acid carriers. These results show that (a) fetuin is far more efficient than albumin in incorporating fatty acids into cells; and (b) this might represent a novel function for fetuin during development.     

The nucleotide and deduced amino acid structures of sheep and pig fetuin. Common structural features of the mammalian fetuin family.

This study was initiated to gain further insight into the structural features of the mammalian fetuin family. The cDNA structures of sheep and pig fetuin were determined. The cDNA insert encoding sheep (pig) fetuin comprised 1550 (1470) nucleotides, including 54 (46) nucleotides encoding a signal peptide of 18 (15) residues and 1038 (1041) nucleotides encoding the 346 (347) amino acids of the mature plasma protein. The predicted amino-terminal sequence of the mature pig fetuin was confirmed by the amino-terminal sequence of the purified protein. However, two alternative sheep amino-terminal sequences were found in fetuin purified from the plasma of a single sheep fetus; the minor product was the one predicted by comparison with other fetuin sequences while the major product was two amino acids longer. Comparison of the deduced amino acid sequences of sheep and pig fetuin showed an extensive sequence identity between them (75%) and with other proteins of the mammalian fetuin family, i.e. human alpha 2-HS glycoprotein, and bovine and rat fetuins. Twelve cysteine residues were found at invariant positions in all fetuin sequences, suggesting strongly that the arrangement of disulphide bridges identified in human alpha 2-HS glycoprotein is common to the members of the family. Further sequence comparisons revealed that the structures of mammalian fetuins are organised in three domains: two cystatin-like domains (D1 and D2) and a complex carboxyl-terminal domain (D3). The proposed three-domain structure of the protein is reflected in the organisation of the rat fetuin structural gene which has recently been published.     

Plasma and urinary clearance rates of atrial natriuretic factor during ontogeny in sheep

The present study was designed to determine the plasma clearance rate of atrial natriuretic factor (ANF) during development in chronically-instrumented fetal, newborn and adult non-pregnant sheep. To determine the contribution of the kidney in the metabolism of ANF, urinary clearance of ANF was also measured. Intravenous infusion of ANF (0.025 and 0.1 microgram.min-1.kg-1) produced a significant decrease in mean arterial blood pressure in newborn lambs and in adult non-pregnant sheep. Estimated plasma ANF clearance rate for the 0.025 and 0.1 microgram.min-1.kg-1 ANF infusion rate were respectively 177 +/- 55 and 155 +/- 34 ml.min-1.kg-1 in fetuses, 138 +/- 26 and 97 +/- 13 ml.min-1.kg-1 in newborn lambs and, 148 +/- 33 and 103 +/- 25 ml.min-1.kg-1 in adult nonpregnant ewes. Fetal, newborn and adult ANF plasma clearance rates during high ANF infusion rate (0.1 microgram.min-1.kg-1) were not significantly different. Low or high ANF infusion rate was not associated with significant changes in urinary ANF concentration or urinary ANF excretion rate. Taken together, the present study demonstrates that ANF plasma clearance rate is similar in fetal, newborn and adult non-pregnant sheep and that the excretory function of the kidney contributes only minimally to ANF plasma clearance rate.     

Somatomedin-C/insulin-like growth factor-I and insulin-like growth factor-II mRNAs in rat fetal and adult tissues

Somatomedin-C or insulin-like growth factor I (Sm-C/IGF-I) and insulin-like growth factor II (IGF-II) have been implicated in the regulation of fetal growth and development. In the present study 32P-labeled complementary DNA probes encoding human and mouse Sm-C/IGF-I and human IGF-II were used in Northern blot hybridizations to analyse rat Sm-C/IGF-I and IGF-II mRNAs in poly(A+) RNAs from intestine, liver, lung, and brain of adult rats and fetal rats between day 14 and 17 of gestation. In fetal rats, all four tissues contained a major mRNA of 1.7 kilobases (kb) that hybridized with the human Sm-C/IGF-I cDNA and mRNAs of 7.5, 4.7, 1.7, and 1.2 kb that hybridized with the mouse Sm-C/IGF-I cDNA. Adult rat intestine, liver, and lung also contained these mRNAs but Sm-C/IGF-I mRNAs were not detected in adult rat brain. These findings provide direct support for prior observations that multiple tissues in the fetus synthesize immunoreactive Sm-C/IGF-I and imply a role for Sm-C/IGF-I in fetal development as well as postnatally. The abundance of a 7.5-kb Sm-C/IGF-I mRNA in poly(A+) RNAs from adult rat liver was 10-50-fold higher than in other adult rat tissues which provides further evidence that in the adult rat the liver is a major site of Sm-C/IGF-I synthesis and source of circulating Sm-C/IGF-I. Multiple IGF-II mRNAs of estimated sizes 4.7, 3.9, 2.2, 1.75, and 1.2 kb were observed in fetal rat intestine, liver, lung, and brain. The 4.7- and 3.9-kb mRNAs were the major hybridizing IGF-II mRNAs in all fetal tissues. Higher abundance of IGF-II mRNAs in rat fetal tissues compared with adult tissues supports prior hypotheses, based on serum IGF-II concentrations, that IGF-II is predominantly a fetal somatomedin. IGF-II mRNAs are present, however, in some poly(A+) RNAs from adult rat tissues. The brain was the only tissue in the adult rat where the 4.7- and 3.9-kb IGF-II mRNAs were consistently detected. Some samples of adult rat intestine contained the 4.7- and 3.9-kb IGF-II mRNAs and some samples of adult liver and lung contained the 4.7-kb mRNA. These findings suggest that a role for IGF-II in the adult rat, particularly in the central nervous system, cannot be excluded.     

Early cortical plate specific glycoprotein in a marsupial species belongs to the same family as fetuin and alpha 2HS glycoprotein

Two related glycoproteins, fetuin in species of the order Artiodactyla (cattle, sheep, pig) and alpha 2HS glycoprotein in the human [(1987) Cell Tissue Res. 248, 33-41] have a very specific distribution in the developing brain. We have isolated and determined the first 15 N-terminal residues of a similarly distributed glycoprotein in the developing brain of the tammar wallaby (Macropus eugenii). The degree of homology is the same between wallaby glycoprotein and alpha 2HS glycoprotein as between fetuin and alpha 2HS glycoprotein (46%). Antibodies made to synthetic peptides of fetuin were used to identify the wallaby glycoprotein. A polyclonal antibody to the purified glycoprotein was used for immunocytochemical identification of brain cells positive for this protein.     

Developmental changes in endothelial nitric oxide synthase expression and activity in ovine fetal lung

Endothelial nitric oxide (NO) synthase (eNOS) produces NO, which contributes to vascular reactivity in the fetal lung. Pulmonary vasoreactivity develops during late gestation in the ovine fetal lung, during the period of rapid capillary and alveolar growth. Although eNOS expression peaks near birth in the fetal rat, lung capillary and distal air space development occur much later than in the fetal lamb. To determine whether lung eNOS expression in the lamb differs from the timing and pattern reported in the rat, we measured eNOS mRNA and protein by Northern and Western blot analyses and NOS activity by the arginine-to-citrulline conversion assay in lung tissue from fetal, newborn, and maternal sheep. Cellular localization of eNOS expression was determined by immunohistochemistry. eNOS mRNA, protein, and activity were detected in samples from all ages, and eNOS was expressed predominantly in the vascular endothelium. Lung eNOS mRNA expression increases from low levels at 70 days gestation to peak at 113 days and remains high for the rest of fetal life. Newborn eNOS mRNA expression does not change from fetal levels but is lower in the adult ewe. Lung eNOS protein expression in the fetus rises and peaks at 118 days gestation but decreases before birth. eNOS protein expression rises in the newborn period but is lower in the adult. Lung NOS activity also peaks at 118 days gestation in the fetus before falling in late gestation and remaining low in the newborn and adult. We conclude that the pattern of lung eNOS expression in the sheep differs from that in the rat and may reflect species-related differences in lung development. We speculate that the rise in fetal lung eNOS may contribute to the marked lung growth and angiogenesis that occurs during the same period of time.     

Cloning and developmental regulation of alpha 1 acid glycoprotein in swine

A cDNA clone of porcine alpha 1 acid glycoprotein (alpha 1AGP) has been isolated and sequenced. Sequence homologies between porcine, human, and rat indicate that porcine alpha 1AGP is similar in structure to the rat and human proteins. RNA blots from days 40, 60, 80, and 110 fetal, newborn, and adult livers showed that alpha 1AGP mRNA is relatively abundant throughout fetal development, particularly at the later stages and in the newborn; there is a rapid decline in abundance following birth. From birth to 3 days of age, there is a three- to four-fold decline in abundance, and alpha 1AGP mRNA is approximately 100 times less abundant in the adult liver than in that of perinatal pigs. Southern blots showed that alpha 1AGP is probably a single-copy gene. The isolation of a cloned cDNA for porcine alpha 1AGP provides a tool to investigate the molecular mechanisms involved in the developmental regulation of the gene and to correlate changes in gene expression during development with fetal growth and well being.     

Characterization of a new alpha-glycoprotein as the major serum component in later fetal and newborn pigs

1. Using crossed immunoelectrophoresis, fetuin, alpha-fetoprotein, albumin, transferrin, alpha1-antitrypsin and a fetospecific-like alpha-glycoprotein, were identified as the main serum components in fetal pig (Sus scrofa domesticus). 2. Fetuin was found to be a trypsin inhibitor, but not a chymotrypsin inhibitor. 3. The fetospecific-like alpha-glycoprotein, not previously reported, accounted for 50% of the total serum proteins in newborn pigs. This protein, however, was a minor component of the adult serum.     

Inhibition of adenylyl cyclase activity in rat corpora luteal tissue by glycopeptides of human chorionic gonadotropin and the alpha-subunit of human chorionic gonadotropin

Indirect evidence has indicated that the carbohydrate moieties of the glycoprotein hormones are involved in the activation of the receptor-adenylyl cyclase system of reproductive tissues. In the present study, we have isolated the glycopeptides (GP) from human chorionic gonadotropin (hCG), the alpha-subunit of hCG, fetuin, and bovine gamma-globulin (b gamma G). These along with a number of synthetic oligosaccharides were tested for their ability to inhibit adenylyl cyclase (AC). There was less than 0.001% cross-reactivity of the GP from hCG, hCG alpha, fetuin, and b gamma G when tested in a double-antibody hCG radioimmunoassay or rat corpora lutea radioreceptor assay. The GP of fetuin, b gamma G, and the synthetic oligosaccharides did not inhibit AC activity of 2000 g corpora lutea membranes when coincubated with 100 ng of hCG/mL (ED50). However, when the GP of hCG and hCG alpha were included with intact hCG, there was a dose-related inhibition. Inhibition of cyclase activity was enhanced when the hCG GP were desialylated. This occurred without a change in the lag time of hCG activation which was calculated to be 1-1.5 min. Changing the concentration of ATP and Mg2+ did not affect the inhibitory effects of the hCG alpha GP on hCG-stimulated AC activity. Inhibition by hCG GP followed uncompetitive kinetics. The inhibition by the GP of hCG seems to be restricted to the LH/hCG-stimulatable AC system because the same dosage of hCG GP which inhibited the rat luteal AC system did not have any effect on the rat hepatocyte AC system when coincubated with glucagon or on NaF-stimulated activity in luteal membranes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunohistochemical localization of pancreatic secretory trypsin inhibitor in fetal and adult pancreatic and extrapancreatic tissues

Pancreatic secretory trypsin inhibitor (PSTI) has been thought to be only a secretory trypsin inhibitor of human pancreas, but the serum content of immunoreactive PSTI is elevated without pancreatic disease. Using the peroxidase-antiperoxidase method, immunoreactive cells for PSTI were found in human pancreas, stomach, duodenum, appendix, colon and urinary tract of both fetus and adult, adult gall bladder, and fetal lung. PSTI-immunoreactive cells were identified in fetal pancreas at the tenth gestational week, and in extrapancreatic tissues at the sixteenth (gastrointestinal and urinary tract) and twentieth weeks (lung). PSTI-immunoreactive cells of fetal lung were present in neuroepithelial bodies. Strongly positive cells in fetal duodenum were argyrophilic and resembled endocrine cells. Immunohistochemical study was also performed on tissues associated with inflammatory diseases of gastrointestinal tract. The distribution pattern of immunoreactive cells in the stomach varied in accordance with chronic gastritis. Immunoreactive cells were also found in endocrine micro-nests and in a carcinoid tumor associated with fundic gastritis. These results suggest that PSTI may play some physiological role other than secretory trypsin inhibition of the pancreas.     

Levels and subcellular distribution of endogenous corticosterone in rat liver during development

The concentration of corticosterone in liver homogenates, liver cytosol and purified nuclear fractions, and in plasma of fetal, newborn, immature and adult rats has been measured by radioimmunoassay.Highest plasma corticosterone levels were found in fetal rats, decreasing close to the levels observed in the adrenalectomized rat by the 6th day of postnatal life followed by a rise in the adult rat. The concentration of corticosterone in liver during development paralleled the plasma levels, the liver to plasma corticosterone ratio ranging between 0.09 and 0.17 suggesting that the corticosterone retained by the tissue is related to the unbound fraction of the hormone in plasma.Both plasma and tissue corticosterone levels declined after adrenalectomy and they were elevated after ether stress.Fractionation of liver homogenates showed that the major fraction of liver corticosterone is localized in the cytosol. Purified liver nuclei contained between 9 and 16% of the total liver corticosterone. The amount of corticosterone in the nuclei seems to be related to the plasma and tissue hormone levels rather than the concentration of cytoplasmic glucocorticoid receptors. Since most of the nuclear corticosterone appears to be bound to receptors, it has been calculated that close to 60% of the cellular receptors in fetal liver are localized in the nucleus. In adult rat liver, only about 10% of the cellular receptors appear to be associated with nuclei. Changes in the concentration of glucocorticoid receptors in liver during development and after adrenalectomy are inversely related to changes in plasma corticosterone levels. It is suggested that corticosterone may regulate the levels of its own receptors in liver.