1
|
Flint AP, Burton RD, Gadsby JE, Saunders PT, Heap RB. Blastocyst oestrogen synthesis and the maternal recognition of pregnancy. Ciba Found Symp 2008:209-38. [PMID: 259040 DOI: 10.1002/9780470720479.ch10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The maternal recognition of pregnancy takes a number of forms in different species; among the eutherian mammals the maintenance of luteal function and cessation of oestrous or menstrual cycles is an important event in early pregnancy. In the pig the embryos signal their presence in the uterus between Days 10 and 12 post coitum; this time corresponds to the onset of blastocyst synthesis of oestrogens, which are luteotrophic in this species, and it has been suggested that oestrogens may constitute an embryonic signal responsible for maintained luteal function in pregnancy. Although oestrone sulphate, which is formed from oestrogens of embryonic origin by uterine sulphotransferase, has been found in the maternal circulation in high concentrations after Day 15 p.c., its appearance is late relative to the time of maternal recognition of pregnancy. Therefore an alternative mechanism has been sought. The recent finding that oestradiol is capable of reducing uterine prostaglandin F2 alpha secretion (i.e. acting as an antiluteolysin), and that it is present in uterine venous blood as early as Day 12 p.c. in pregnant pigs, suggests a mechanism whereby blastocyst oestrogens may be capable of influencing luteal function.
Collapse
|
2
|
Gaunt SJ, Dean W, Sang H, Burton RD. Evidence that Hoxa expression domains are evolutionarily transposed in spinal ganglia, and are established by forward spreading in paraxial mesoderm. Mech Dev 1999; 82:109-18. [PMID: 10354475 DOI: 10.1016/s0925-4773(99)00018-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transposition of anatomical structures along the anteroposterior axis has been a commonly used mechanism for changing body proportions during the course of evolutionary time. Earlier work (Gaunt, S.J., 1994. Conservation in the Hox code during morphological evolution. Int. J. Dev. Biol. 38, 549-552; Burke, A.C., Nelson, C.E., Morgan, B.A., Tabin, C., 1995. Hox genes and the evolution of vertebrate axial morphology. Development 121, 333-346) showed how transposition in mesodermal derivatives (vertebrae) could be attributed to transposition in the expression of Hox genes along the axial series of somites. We now show how transposition in the segmental arrangement of the spinal nerves can also be correlated with shifts in the expression domains of Hox genes. Specifically, we show how the expression domains of Hoxa-7, a-9 and a-10 in spinal ganglia correspond similarly in both mouse and chick with the positions of the brachial and lumbosacral plexuses, and that this is true even though the brachial plexus of chick is shifted posteriorly, relative to mouse, by seven segmental units. In spite of these marked species differences in the boundaries of Hoxa-7 expression, cis regulatory elements located up to 5 kb upstream of the chick Hoxa-7 gene showed much functional and structural conservation with those described in the mouse (Puschel, A.W., Balling, R., Gruss, P., 1991. Separate elements cause lineage restriction and specify boundaries of Hox-1.1 expression. Development 112, 279-287; Knittel, T., Kessel, M., Kim, M.H., Gruss, P., 1995. A conserved enhancer of the human and murine Hoxa-7 gene specifies the anterior boundary of expression during embryonal development. Development 121, 1077-1088). We also show that chick Hoxa-7 and a-10 expression domains spread forward into regions of somites that are initially negative for the expression of these genes. We discuss this as evidence that Hox expression in paraxial mesoderm spreads forward, as earlier found for neurectoderm and lateral plate mesoderm, in a process that occurs independently of cell movement.
Collapse
Affiliation(s)
- S J Gaunt
- Department of Development and Genetics, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK.
| | | | | | | |
Collapse
|
3
|
Tiller PR, Cunniff J, Land AP, Schwartz J, Jardine I, Wakefield M, Lopez L, Newton JF, Burton RD, Folk BM, Buhrman DL, Price P, Wu D. Drug quantitation on a benchtop liquid chromatography-tandem mass spectrometry system. J Chromatogr A 1997; 771:119-25. [PMID: 9210315 DOI: 10.1016/s0021-9673(97)00147-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The specificity and selectivity of LC-MS-MS is illustrated to explain why LC-MS-MS has become the method of choice for quantitation within the pharmaceutical industry. Two assays are described that demonstrate the facility with which new ion trap technology can utilize the selectivity and sensitivity of LC-MS-MS to quantitate trace level components within complex matrices, in particular human plasma. One assay undergoes a validation procedure and demonstrates the utility of this new technology for drug quantitation within a regulated environment.
Collapse
|
4
|
Abstract
A human clone corresponding to the homologue of the murine Polycomb-like gene M33 has been used to map this gene (CBX2) to human chromosomes. Both somatic cell hybrid panels and FISH on metaphase chromosomes have been used. These techniques gave a consistent localization, at the tip of the long arm of chromosome 17 (17q25). This localization, as well as the potential role of a mammalian Polycomb-like protein, suggests a potential involvement in two different pathologies: the campomelic syndrome, an inherited disorder, and neoplastic disorders linked to allele loss already described in this region.
Collapse
Affiliation(s)
- J Gecz
- INSERM U242, Marseille, France
| | | | | | | | | | | | | |
Collapse
|
5
|
Burton RD. Your vote and the future of medicine. Mich Med 1992; 91:72, 71. [PMID: 1620008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
6
|
Singh PB, Miller JR, Pearce J, Kothary R, Burton RD, Paro R, James TC, Gaunt SJ. A sequence motif found in a Drosophila heterochromatin protein is conserved in animals and plants. Nucleic Acids Res 1991; 19:789-94. [PMID: 1708124 PMCID: PMC333712 DOI: 10.1093/nar/19.4.789] [Citation(s) in RCA: 216] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Modifiers of position-effect-variegation in Drosophila encode proteins that are thought to modify chromatin, rendering it heritably changed in its expressibility. In an attempt to identify similar modifier genes in other species we have utilized a known sequence homology, termed chromo box, between a suppressor of position-effect-variegation, Heterochromatin protein 1 (HP1), and a repressor of homeotic genes, Polycomb (Pc). A PCR generated probe encompassing the HP1 chromo box was used to clone full-length murine cDNAs that contain conserved chromo box motifs. Sequence comparisons, in situ hybridization experiments, and RNA Northern blot analysis suggest that the murine and human sequences presented in this report are homologues of the Drosophila HP1 gene. Chromo box sequences can also be detected in other animal species, and in plants, predicting a strongly conserved structural role for the peptide encoded by this sequence. We propose that epigenetic (yet heritable) changes in gene expressibility, characteristic of chromosomal imprinting phenomena, can largely be explained by the action of such modifier genes. The evolutionary conservation of the chromo box motif now enables the isolation and study of putative modifier genes in those animal and plant species where chromosomal imprinting has been described.
Collapse
Affiliation(s)
- P B Singh
- Department of Molecular Embryology, Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Abstract
The cytosolic glucocorticoid receptor of ovine placental zona intima has been characterized and measured between day 51 of pregnancy and term, and levels compared with those in fetal lung. By ion-exchange and gel-filtration chromatography the molybdate-stabilized receptor was found to be an acidic molecule with Stokes radius approximately 8 nm; these physicochemical characteristics of the ovine placental receptor are comparable to those of receptors in glucocorticoid target tissues from nonruminants. Concentrations of cytosolic receptor in placenta (mean, 139 fmol/mg protein) were lower than those in fetal lung (627 fmol/mg) at all stages of gestation investigated. To some extent this difference was accounted for by a twofold higher concentration of protein in placental cytosols compared with those from fetal lung. In both tissues, cytosolic receptor concentrations were maximal between days 91 and 130, when fetal adrenal steroid secretion is low; receptor concentrations decreased before term. Fetal hypophysectomy, which resulted in prolonged gestation, raised receptor concentrations in placenta, but not in fetal lung. In both tissues, apparent dissociation constants for [3H]dexamethasone binding to glucocorticoid receptors were in the range 0.5-7.1 nmol/l; these dissociation constants did not change consistently between day 100 and term. In whole-cell preparations of placenta and fetal lung incubated in vitro there was time-dependent specific binding of [3H]dexamethasone by nuclei, and binding of labelled cytosolic receptor to isolated nuclei occurred at all stages of gestation investigated. Binding of [3H]dexamethasone by cytosolic receptor from placenta and fetal lung was inhibited by progesterone and 17 alpha-hydroxyprogesterone, as well as by cortisol, cortisone, 11-deoxycorticosterone and 11 beta-hydroxyprogesterone; 20 alpha-hydroxyprogesterone and 17 alpha,20 alpha-dihydroxypregn-4-en-3-one were less effective. In experiments to evaluate the possible antagonistic action of progesterone in whole-cell preparations, uptake of [3H]dexamethasone by nuclei was increased up to twofold in placental minces incubated with aminoglutethimide or epostane, when progesterone synthesis was reduced by 98 and 92 per cent respectively. Nuclear uptake in minces of fetal lung was blocked by concentrations of progesterone found in placenta. The existence of a placental glucocorticoid receptor confirms that fetal cortisol may act directly on the placenta to induce the enzymatic changes controlling the onset of labour.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
|
8
|
Abstract
Concentrations of progesterone in arterial and ovarian, uterine and jugular venous plasma were determined in four Barbary sheep at various stages of pregnancy. The results, together with ovarian histology, show that the corpus luteum regresses before term in Barbary sheep, as in most breeds of domestic ewes. Uterine synthesis of progesterone was demonstrated in late pregnancy in two animals in which uterine venous levels of progesterone were increased two- to fourfold above arterial concentrations. The placenta contained 3 beta-hydroxysteroid dehydrogenase. Barbary sheep (diploid chromosome number, 2N = 58) therefore resemble the domestic sheep (2N = 54) rather than the goat (2N = 60) from the point of view of the source of the progesterone required for maintenance of pregnancy.
Collapse
|
9
|
Flint AP, Burton RD, Gadsby JE, Heap RB, Sheldrick EL. Embryonic steroid synthesis and luteal oxytocin production: controlling mechanisms for the maternal recognition of pregnancy. J Steroid Biochem 1983; 19:973-8. [PMID: 6887912 DOI: 10.1016/0022-4731(83)90042-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In both pigs and sheep in early pregnancy the function of the corpora lutea is maintained beyond the normal time of luteal regression. The mechanism by which this is brought about appears in both species to involve reduced uterine secretion of the uterine luteolysin, prostaglandin F2 alpha, as a result of the secretion of an embryonic antiluteolysin. In the pig this antiluteolysin is an oestrogen, and in the sheep, the protein trophoblastin. Loss of luteal oxytocin also occurs in sheep early in pregnancy, and this may contribute to reduced luteolytic drive during the period between 25 and 50 days of gestation when the embryonic antiluteolysin is absent. Concentrations of oxytocin in the corpora lutea appear to be controlled by a factor of uterine origin, since luteal oxytocin is also depleted after hysterectomy.
Collapse
|
10
|
Burton RD. Michigan MDs support mandatory seat belt use. Mich Med 1982; 81:465-6. [PMID: 7176956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
11
|
Burton RD. Swing-bed concept in Utah . . . a decade of experience 1982. J Patient Acc Manage 1982:10-6. [PMID: 10255294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
|
12
|
Burton RD. "Meeting the challenge of the 80s" MSMS public relation focus for 1982. Mich Med 1982; 81:135-40. [PMID: 7070289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
13
|
Burton RD. MSMS public service committee emphasizes education. Mich Med 1981; 80:516-8. [PMID: 7339448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
14
|
Burton RD. Conversations with over 600 form basis for MSMS survey. Mich Med 1981; 80:517. [PMID: 7339449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
15
|
Findlay JK, Ackland N, Burton RD, Davis AJ, Walker FM, Walters DE, Heap RB. Protein, prostaglandin and steroid synthesis in caruncular and intercaruncular endometrium of sheep before implantation. J Reprod Fertil 1981; 62:361-77. [PMID: 7252919 DOI: 10.1530/jrf.0.0620361] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The effect of the presence of a preimplantation embryo on protein concentration, rate of protein synthesis, beta-glucuronidase and acid phosphatase activities, steroid metabolism and prostaglandin F production in caruncular and intercaruncular tissue have been studied for sheep at Day 15 of pregnancy. The rate of protein synthesis in both tissues was greater in pregnant than in non-pregnant animals, although the difference was only significant in caruncular endometrium. The effect in caruncular tissue was mimicked in ovariectomized animals treated with oestradiol. Localized changes in the caruncular tissue were observed in respect of PGF with an increased tissue concentration, an enhanced basal release when the tissue was incubated in the presence of indomethacin, and a decreased net production. Maximum production of PGF in the 2 tissues was unaffected by the presence of an embryo but it was enhanced by oestradiol or progesterone treatment in intercaruncular tissue of ovariectomized ewes. beta-Glucuronidase and acid phosphatase activities and steroid metabolism were unaffected by pregnancy. However, in ovariectomized animals oestradiol treatment stimulated beta-glucuronidase activity in endometrium and myometrium. Progesterone treatment stimulated acid phosphatase activity in the intercaruncular endometrium. The results show that amongst several endometrial constituents investigated relatively few changes were detected by Day 15 post coitum, one day before definitive attachment. Those changes that did occur were associated with the dynamics of PGF production and the rate of protein synthesis, and were consistent with the production of a PGF binding component in caruncular endometrium which may be concerned with the protection of luteal function by redirection of uterine PGF production. Canonical variate analysis revealed that changes on Day 15 of pregnancy were mimicked most closely in caruncular tissue by treatment of ovariectomized ewes with oestradiol and progesterone, and in intercaruncular tissue by oestradiol treatment only.
Collapse
|
16
|
Abstract
Yolk sac and endometrial tissue were obtained from tammar wallabies between 11 and 25 days after the removal of pouch young. Tissues were examined histologically and steroid-metabolizing enzymes were identified by incubation for 3 h at 37 degrees C in Medium 199 containing labelled steroid precursors. Yolk sac membrane (YSM) incubated with labelled pregnenolone produced a small amount of progesterone and pregnanediols; 80.5 +/- 8.4 (S.E.M.) % of the original substrate remained unmetabolized. Labelled androstenedione was metabolized to 5 alpha-androstane-3,17-dione and androsterone, and only 5.8 +/- 3.8% of the original substrate remained at the end of incubation. Incorporation of androstenedione or dehydroepiandrosterone (DHA) into phenolic compounds was low (0.5 +/- 0.1%). There was no evidence for the enzymes, arylsulphatase or sulphotransferase, in YSM. Endometrial tissue from the same animals metabolized pregnenolone, DHA and androstenedione, converted progesterone to androstenedione, and produced aqueous-soluble steroid conjugates. The results demonstrated that YSM contains enzymes associated predominantly with steroid catabolism and with incipient progesterone synthesis. The findings are discussed in relation to the histological appearance of the tissues and compared with placental steroid synthesis in eutherian mammals.
Collapse
|
17
|
Abstract
Oestrogen synthesis by the early embryo in vitro was studied with tissue from pigs, sheep, cows, roe deer, ferrets, cats, rabbits and a plains viscacha. Definitive evidence for aromatase activity and oestrogen synthesis in preimplantation trophoblast was obtained for the pig with the formation of oestrone, oestradiol-17 beta and oestradiol-17 alpha from 3H-labelled androstenedione and dehydroepiandrosterone. Aromatase activity was appreciably lower in all other species studied, and labelled oestrogens were recovered only from incubations of allantochorionic tissue of roe deer, recovered shortly after implantation, and from pooled samples of early embryonic tissue of cows. High aromatase activity in preimplantation trophoblast of pigs was associated with the maternal recognition of pregnancy and the occurrence of superficial implantation in this species.
Collapse
|
18
|
Heap RB, Perry JS, Gadsby JE, Burton RD, Wyatt C. Endocrine activities and protein synthesis in the early blastocyst. Biochem Soc Trans 1977; 5:457-8. [PMID: 902864 DOI: 10.1042/bst0050457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
19
|
Perry JS, Heap RB, Burton RD, Gadsby JE. Endocrinology of the blastocyst and its role in the establishment of pregnancy. J Reprod Fertil Suppl 1976:85-104. [PMID: 137974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
20
|
Perry JS, Heap RB, Burton RD. Proceedings: Oestrogen metabolism by trophoblast and endometrium, and its probable relation to luteal maintenance in the pig. J Endocrinol 1975; 64:40P-41P. [PMID: 1169279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
21
|
|