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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A codon-based approach to estimating the number of variable sites in a protein is presented. When first and second positions of codons are assumed to be replacement positions, a capture-recapture model can be used to estimate the number of variable codons from every pair of homologous and aligned sequences. The capture-recapture estimate is compared to a maximum likelihood estimate of the number of variable codons and to previous approaches that estimate the number of variable sites (not codons) in a sequence. Computer simulations are presented that show under which circumstances the capture-recapture estimate can be used to correct biases in distance matrices. Analysis of published sequences of two genes, calmodulin and serum albumin, shows that distance corrections that employ a capture-recapture estimate of the number of variable sites may be considerably different from corrections that assume that the number of variable sites is equal to the total number of positions in the sequence.
J Mol Evol 1992 Sep
PMID:Estimating the fraction of invariable codons with a capture-recapture method. 151 92

An antibody to androstanedione obtained in a rabbit by immunization with androstenedione-7 alpha-carboxymethyl-thioether conjugated to bovine serum albumin was found to cross-react 100% with 5 alpha-androstane-3,17-dione, a property that was used to develop a radioimmunoassay for this steroid. Plasma 5 alpha-androstane-3,17-dione concentrations were determined in young men, and in women throughout an ovulatory cycle. In the men (n = 6), plasma 5 alpha-androstane-3,17-dione concentrations were in the range of 84 to 273 pg/ml with a mean (+/- SD) value of 164 +/- 57 pg/ml. The plasma levels in the women (n = 5) were in the ranges of 35 +/- 14 to 145 +/- 75 pg/ml during the follicular phase, and 109 +/- 50 to 151 +/- 44 pg/ml during the luteal phase. The tissue sites of origin of 5 alpha-androstane-3,17-dione have not been defined, however, some extraglandular tissues are known to contain enzymes that convert C19-steroids to 5 alpha-androstane-3,17-dione. It is possible that 5 alpha-androstane-3,17-dione in circulation serves as a substrate for peripheral synthesis of 5 alpha-dihydrotestosterone.
J Steroid Biochem Mol Biol 1992 Feb
PMID:5 alpha-androstane-3,17-dione in peripheral plasma of men and women. 154 87

The aim of this study was to establish the minimum conditions required to maintain adult rat Leydig cell testosterone production and luteinizing hormone (LH) responsiveness in short term culture, at a level similar to that observed in vivo, which could be used to study factors which may have a delayed or chronic effect on Leydig cell function. Percoll gradient-purified adult rat Leydig cells (5.0 x 10(4)/250 microliters) were cultured in Dulbecco's modified Eagle's medium/Ham's F12 (DMEM/F12) with 0.1% bovine serum albumin at 32 degrees C for up to 3 days, with daily medium changes. A combination of submaximal rat LH (0.1 ng/ml) and a maximal concentration of rat serum lipoproteins (0.5 mg/ml) maintained testosterone production at between 5 and 15 ng/10(6) cells/h; subsequent stimulation of the Leydig cells with a maximum dose of rat LH (8 ng/ml) over 24 h resulted in testosterone production of 75-240 ng/10(6) cells/h on all 3 days of culture. However, the addition of 0.1% fetal calf serum instead of rat lipoproteins could not maintain LH-stimulated testosterone production in the same culture period. In cultures containing submaximal LH and lipoproteins, levels of testosterone production and responses to maximal LH stimulation were constant over the culture period when expressed as either testosterone production per 10(6) cells plated, or testosterone production per microgram DNA recovered at end of incubation. Reduction of the oxygen tension from 19% to 5%, or to 1% did not significantly alter testosterone production by Leydig cells under these established conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1992 Feb
PMID:Adult rat Leydig cell cultures: minimum requirements for maintenance of luteinizing hormone responsiveness and testosterone production. 154 7

The ability of domestic cat or leopard cat spermatozoa to penetrate zonae pellucidae (ZP) of salt-stored, domestic cat oocytes was examined as an assay for sperm capacitation. Ovarian oocytes were recovered after ovariectomy and matured in vitro for 18-36 h. Following removal of cumulus cells, the oocytes were used fresh, or stored (4 degrees C, 0.5-24 weeks) in a HEPES-buffered hypertonic salt solution. Electroejaculated, washed sperm (2-4 x 10(6) sperm/ml) were preincubated for 1.0 h (38 degrees C, 5% CO2 in air) and then co-incubated (2 x 10(5) sperm/ml) with fresh or stored oocytes for 6.0 h. Gametes were incubated in a protein-free, modified Tyrode's solution (TLP-PVA) or in the same medium containing 4.0 mg/ml bovine serum albumin (BSA; TALP-PVA). Treatments were compared for percentage ZP penetration (defined as sperm heads reaching more than halfway through the ZP) as an index of sperm capacitation. In both the domestic cat and leopard cat, there was no difference (P greater than 0.05) in sperm penetration of fresh ZP (domestic cat, 42.5 +/- 5.4%; leopard cat, 38.6 +/- 2.8%) or stored ZP (domestic cat, 32.4 +/- 4.2%; leopard cat, 27.6 +/- 2.3%). Sperm incubated in protein-free medium (TLP-PVA) were less capable (P less than 0.05) of ZP penetration (domestic cat, 14.6 +/- 5.9%; leopard cat, 7.9 +/- 3.0%) than sperm incubated in medium TALP-PVA containing BSA (domestic cat, 60.3 +/- 5.9%; leopard cat, 58.4 +/- 3.0%).(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1992 Mar
PMID:Sperm capacitation in the domestic cat (Felis catus) and leopard cat (Felis bengalensis) as studied with a salt-stored zona pellucida penetration assay. 155 5

The type of plasminogen activator (PA) secreted by bovine embryos was identified. Day 12-14 embryos were collected from estrus-synchronized, superovulated, and naturally mated crossbred beef cows. Embryos were left intact (E) or microdissected into component embryonic discs (ED) and trophoblastic vesicles (TV). Intact embryos, ED, and TV were pre-cultured for 2 days in Minimum Essential Medium Alpha (MEM alpha) with 10% heat-inactivated fetal calf serum, washed in serum-free MEM alpha, and cultured individually for 5 days in 50 microliters microdrops of MEM alpha with 15 mg/ml bovine serum albumin. At 24 hr intervals, E, ED, and TV were observed for tissue morphology and transferred to fresh microdrops, and medium was recovered and frozen at -20 degrees C. At the end of culture, blastocoelic fluid (BF) and embryonic tissues were recovered and frozen at -20 degrees C. Plasminogen activator concentrations in medium, tissues, and BF were determined by using a caseinolytic assay. Antibodies to urokinase-type PA (anti-uPA) and tissue-type PA (anti-tPA), and the urokinase inhibitor, amiloride (AMR), were used to identify the type of PA produced by bovine embryonic tissues. Intact embryos and TV released more PA (P less than 0.05) than ED, and tissues exhibiting expanded blastocoels released less PA (P less than 0.05) than tissues with collapsed blastocoels. Blastocoelic fluid from TV exhibited more PA (P less than 0.05) activity than from ED. Treatment with anti-uPA decreased PA activity (P less than 0.05) in pooled medium and tissues from E compared to treatment with nonspecific immunoglobulins and anti-tPA.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1992 Jan
PMID:Bovine embryos produce a urokinase-type plasminogen activator. 156 22

The objective of this study was to examine the effects of different culture media used for maturation of bovine oocytes on in vitro embryo development following in vitro fertilization. Oocytes were aspirated from 2-5 mm follicles of ovaries collected at a local abattoir. The oocyte-cumulus complexes (OCCs) were cultured for 23-25 h in one of seven commercially available media supplemented with 6 mg/ml bovine serum albumin (BSA), 0.25 mM pyruvate, 10 micrograms/ml luteinizing hormone (LH), 0.5 microgram/ml follicle-stimulating hormone (FSH), and 1 microgram/ml estradiol. After maturation for 23-25 h, all eggs were subjected to the same in vitro fertilization protocol using modified TALP medium and subsequently cultured in the same serum-free embryo culture medium (HECM-1/BSA) for 8 days, after which embryo development was assessed. Five media (SFRE, MEM alpha, TCM199, MEM alpha/+, RPMI:MEM alpha) better supported normal oocyte maturation as determined by embryo development to the two-cell (76-82%), morula/blastocyst (25-32%), and blastocyst (12-19%) stages. Oocytes that were matured in Waymouth's medium MB 752/l or Ham's F-12 had a significantly reduced incidence of cleavage to the two-cell stage (52% and 37%, respectively), which was not attributed to failure of fertilization. Of the eggs that did cleave to the two-cell stage in these two media, 27% and 9% developed to morulae/blastocysts but only 6% and 3%, respectively, developed into blastocysts.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Reprod Dev 1992 Jan
PMID:Effect of oocyte maturation medium on in vitro development of in vitro fertilized bovine embryos. 156 30

The binding of estrone-3-sulfate (E1-3-S) and estradiol-3-sulfate (E2-3-S) to adult stallion plasma was determined and compared with the binding to equine serum albumin (ESA). On the ESA molecule, two binding sites for E1-3-S with an association constant of 1.3 x 10(5) M-1 and several sites of weaker affinity were found; the data for E2-3-S showed the existence of four binding sites of moderate affinity (1 x 10(5) M-1) and several sites of weaker affinity. The removal of albumin from the stallion plasma resulted in the absence of binding of E1-3-S or E2-3-S, whereas the removal of glycoproteins resulted in binding parameters similar to those obtained with whole plasma. These results indicate that ESA is the only estrogen sulfate binder in horse plasma. Under physiological conditions, 95% of E1-3-S was bound to ESA.
J Steroid Biochem Mol Biol 1992 May
PMID:Binding of estrogen-3-sulfates to stallion plasma and equine serum albumin. 160 45

Cells of Candida albicans WO-1 spontaneously switch between a white and opaque CFU, and this phase transition involves a dramatic change in cellular phenotype. By using a differential hybridization screen, an opaque-specific cDNA, Op1a, which represents the transcript of a gene regulated by switching, has been isolated. The gene for Op1a is transcribed by opaque but not by white cells. The nucleotide sequence of the Op1a cDNA reveals over 99% base homology with an acid protease gene of C. albicans, and the predicted amino acid sequence demonstrates that the product of this gene is a member of the family of pepsinogens, which possess a hydrophobic leader sequence for secretion and two catalytic aspartate domains. Southern blots of both genomic DNA digested with 14 different endonucleases and electrophoretically separated chromosomes were probed with the Op1a cDNA. No polymorphisms were detected in either case between white and opaque cells, suggesting that no genomic reorganization occurs in the proximity of the gene during the white-opaque transition. Although transcription of Op1a correlates with the high levels of extracellular protease activity in opaque cell cultures and the absence of activity in white cell cultures, stimulation of extracellular protease activity by addition of serum albumin is not accompanied by Op1a transcription in cultures of WO-1 white cells or cultures of two additional clinical isolates of C. albicans, suggesting that expression of one or more other protease genes is stimulated in these cases. The results demonstrate that transcription of the Op1a gene is under the rigid control of switching in strain WO-1.
Mol Cell Biol 1992 Jul
PMID:Transcription of the gene for a pepsinogen, PEP1, is regulated by white-opaque switching in Candida albicans. 162 Jan 10

Within the framework of experiments related to the association between dietary fiber and breast cancer an in vitro test system was used to study the binding of estrogens to various fibers (e.g. cholestyramin, lignin and cellulose) and fiber sources (e.g. wheat bran, cereals, seeds and legumes). Furthermore, the in vivo apparent digestibility of the different fiber sources was tested using a mobile nylon bag technique in intestine-cannulated pigs. Estradiol-17 beta (E2) bound more strongly to the various fibers than did estrone (E1), estriol or estrone-3-glucuronide. At increasing pH (greater than 7) binding of both E1 and E2 to wheat bran decreased significantly. Cholestyramine and lignin bound almost all estrogens present in the medium. Linseed (91%), oats (83%), barley chaff (88%) and wheat bran (82%) are other excellent binders of E2. Corn, rye and white wheat flour showed lower binding capacity with a relatively low affinity. Cereals with the highest percentage of lignin in the fiber (greater than 3%) were also the fiber sources with the lowest apparent digestibility. Estrogens bound with the highest affinity (relative to bovine serum albumin) to these fiber sources. Together with wheat bran and lignin, oats, linseed and soybean seem to be products with good perspectives for in vivo evaluation of the lowering effect of dietary fiber on estrogen exposure of estrogen-sensitive tissues.
J Steroid Biochem Mol Biol 1991 May
PMID:In vitro binding of estrogens by dietary fiber and the in vivo apparent digestibility tested in pigs. 164 89

Arthritis was induced by injecting cationic amidated bovine serum albumin (aBSA) (pI approximately 9.2) into the knee joint of immunized guinea pigs and the mechanisms of articular cartilage destruction were studied morphologically and biochemically. Marked synovitis associated with polymorphonuclear leukocyte (PML) infiltration occurred within 1 day of the challenge. Articular cartilage infiltrated by PMLs was almost completely destroyed after 2 weeks. During the initial destructive process, proteoglycans were depleted from the cartilage and later collagen fibers disappeared. Granulation tissue growing in the inflamed synovium and bone marrow replaced the destroyed cartilage and joint cavity and formed fibrous scar tissue (fibrous ankylosis) by 8 weeks. Subsequently, the knee joints developed cartilagenous ankylosis by 12 weeks and finally bony ankylosis at 28 weeks. Autoradiography using 125I-aBSA and immunofluorescence studies for immunoglobulin (IgG) and complement (C3) demonstrated that the antigen is trapped in all zones of the articular cartilage and serves as a trigger for immune complex formation. Significantly increased neutral proteinase activities against substrates of proteoglycan subunits, [3H]carboxymethylated transferrin and L-pyroglutamyl-L-prolyl-L-valine-paranitroanilide were detected in homogenates of the synovium and cartilage from arthritic knee joints 1 and 2 weeks after induction. Inhibitor studies and pH curves suggested that the proteinase is leukocyte elastase. Measurable amounts of gelatinolytic activity, detected by activation with 4-aminophenylmercuric acetate and inhibited with EDTA, were also present in the same samples, but there was no detectable collagenase activity. The data on SDS-gelatin substrate gel showed that the proteinase is gelatinase derived from PMLs. These results suggest that in aBSA-induced arthritis, elastase and gelatinase from PMLs invading articular cartilage may play important roles in cartilage destruction.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Arthritis induced immunologically with cationic amidated bovine serum albumin in the guinea pig. A morphological and biochemical study on the destruction of articular cartilage. 167 78


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