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1.
Pregnancy-associated plasma protein-A (PAPP-A) is a human macromolecular glycoprotein produced by the trophoblast and possibly by the decidua. Its biological function is unknown, but in vitro, PAPP-A has been reported to be an inhibitor of granulocyte elastase. The present study was undertaken to see if pregnant cynomolgus monkeys could be an animal model sufficiently close to the human situation to study the physiology of PAPP-A. An antiserum to pregnant cynomolgus plasma was raised in rabbits. After adsorption with normal monkey plasma, this antiserum was used together with radioiodinated human PAPP-A to develop an heterologous radioimmunoassay for measurements of monkey PAPP-A. On polyacrylamide gel electrophoresis, it was shown that this polyspecific-antiserum bound the same molecular species of radioiodinated human PAPP-A as the available anti-human PAPP-A antiserum. The concentrations of cynomolgus PAPP-A (cPAPP-A) throughout pregnancy follow the same pattern as human PAPP-A (hPAPP-A) with an almost exponential increase up to term. The doubling time of cPAPP-A was similar to that of hPAPP-A. After RU 486-induced abortion or after spontaneous abortion, the levels of cPAPP-A decreased, with an apparent half-life of 2-3 days. Preliminary characterization of cPAPP-A revealed that although cPAPP-A was only immunologically related to hPAPP-A, it was biochemically very similar: they had the same PI and the same molecular weight, and both PAPP-As bound heparin. It is concluded that pregnant cynomolgus monkeys are a good model to study the physiology of PAPP-A. 相似文献
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Extracellular matrix influences hormone and protein production by human chorionic villi 总被引:4,自引:0,他引:4
Summary Increasing evidence confirms that the extracellular matrix greatly influences cell behaviour and function. Collagen and fibrin are in contact with trophoblast throughout pregnancy. To investigate whether these two matrices influence hormon production by the trophoblast, explants from first-trimester chorionic villi were cultured for up to 30 days either a) in medium with agitation, b) embedded in type-I collagen (three-dimensional gels), or c) embedded in fibrin (three-dimensional gels). The supernatant culture medium was changed every 48 h and tested by radioimmunoassay for hCG, progesterone and pregnancy-associated plasma protein A. In addition, after 3, 7, 15, and 30 days of culture villi were fixed and studied by light and electron microscopy. Embedding in the extracellular matrix showed higher and longer-lasting production rates of all measured products and superior structural preservation as compared to cultures with agitation. Collagen matrix proved to be superior to fibrin. As established by several tests, this difference was neither due to thrombin used to polymerize fibrinogen, nor to differences in the diffusion rates through the two different matrices used. We conclude that extracellular matrix, particularly collagen, influences the synthesis of trophoblastic products. Embedding of the villous explants in three-dimensional gels constitutes a new method for long-term cultures of chorionic villi.This study was presented at the workshop Placental-and decidual-specific protein synthesis and secretion: regulation, role and interaction, Zemun, Belgrade, Yugoslavia, 19–20 May, 1988 (Bischof and Castellucci 1988; see also J. Aplin 1989), and at the 11th Rochester Trophoblast Conference, Rochester, N.Y. USA, 9–12 October 1988 (Castellucci et al. 1988) 相似文献
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The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
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