scholarly journals Evidence from rat liver nuclear preparations that latency of microsomal UDP-glucuronosyltransferase is associated with vesiculation

1980 ◽  
Vol 186 (3) ◽  
pp. 687-691 ◽  
Author(s):  
G J Wishart ◽  
D J Fry
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Glucuronic Acid ◽  
Udp Glucuronosyltransferase

1. Nuclear, nuclear-envelope and microsomal preparations were prepared from rat liver, and their purity and morphology monitored by electron microscopy. 2. UDP-glucuronosyltransferase activity in microsomal preparations, but not in standard nuclear or nuclear-envelope preparations, displays latency from the criterion of being enhanced (‘activated’) by a range of detergents or the endogenous activator UDP-N-acetyl-glucosamine. 3. Nuclear preparations resemble activated rather than native microsomal preparations in failing to transfer glucuronic acid from 4-nitrophenyl glucuronide to 2-aminophenol. 4. Electron microscopy indicates that membranes of nuclear preparations and of our standard nuclear-envelope preparations remain, as in vivo, in a cisternal arrangement, whereas those of microsomal preparations are vesiculated. 5. In nuclear-envelope preparations in which vesiculation has been encouraged, the transferase can be activated by detergents. 6. We suggest that latency of UDP-glucuronosyltransferase results from vesiculation of membranes during preparation and that the latency of the microsomal transferase is largely a preparative artefact.

scholarly journals ELECTRON MICROSCOPY OF MITOSIS IN AMEBAE

1967 ◽  
Vol 34 (1) ◽  
pp. 47-59 ◽  
Author(s):  
L. E. Roth
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Metaphase Plate ◽  
Test Sequence ◽  
Partial Loss ◽  
Mitotic Apparatus ◽  
In Vivo Test ◽  
Characteristic Sequences ◽  
Inhibitor Compounds

The mitotic apparatus (MA) of the giant ameba, Chaos carolinensis, has characteristic sequences of microtubule arrays and deployment of nuclear envelope fragments. If mitotic organisms are subjected to 2°C for 5 min, the MA microtubules are completely degraded, and the envelope fragments are released from the chromosomes which remain condensed but lose their metaphase-plate orientation. On warming, microtubules reform but show partial loss of their parallel alignment; displacement of the envelope fragments persists or is increased by microtubule reformation. This study demonstrates that cooling causes destruction of microtubules and intermicrotubular cross-bonds and further shows that such controlled dissolution and reformation can provide an in vivo test sequence for studies on the effects of inhibitor-compounds on microtubule subunit aggregation. Urea, at the comparatively low concentration of 0.8 M, inhibited reformation following cooling and rewarming but was ineffective in altering microtubules that had formed before treatment.

scholarly journals On the localisation of d-tubocurarine in rat liver lysosomes in vivo by electron microscopy and subcellular fractionation

1975 ◽  
Vol 289 (3) ◽  
pp. 251-256 ◽  
Author(s):  
Jeanette G. Weitering ◽  
Gerard J. Mulder ◽  
Dirk K. F. Meijer ◽  
Wim Lammers ◽  
Maarten Veenhuis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rat Liver ◽  
Subcellular Fractionation ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes

scholarly journals Hepatic Golgi fractions resolved into membrane and content subfractions.

1982 ◽  
Vol 92 (3) ◽  
pp. 822-832 ◽  
Author(s):  
K E Howell ◽  
G E Palade
Keyword(s):  
Electron Microscopy ◽  
Rat Liver ◽  
Enzyme Activities ◽  
Degree Of Contamination ◽  
Golgi Membranes ◽  
Membrane Enzyme ◽  
Biochemical Assays ◽  
The Reformation ◽  
Liver Homogenates

Golgi fractions isolated from rat liver homogenates have been resolved into membrane and content subfractions by treatment with 100 mM Na2CO3 pH 11.3. This procedure permitted extensive extraction of content proteins and lipoproteins, presumably because it caused an alteration of Golgi membranes that minimized the reformation of closed vesicles. The type and degree of contamination of the fractions was assessed by electron microscopy and biochemical assays. The membrane subfraction retained 15% of content proteins and lipids, and these could not be removed by various washing procedures. The content subfraction was contaminated by both membrane fragments and vesicles and accounted for 5 to 10% of the membrane enzyme activities of the original Golgi fraction. The lipid compositions of the subfractions was determined, and the phospholipids of both membrane and content were found to be uniformly labeled with [33P]phosphate administered in vivo.

scholarly journals Glucuronidation of the environmental oestrogen bisphenol A by an isoform of UDP-glucuronosyltransferase, UGT2B1, in the rat liver

1999 ◽  
Vol 340 (2) ◽  
pp. 405-409 ◽  
Author(s):  
Hiroshi YOKOTA ◽  
Hidetomo IWANO ◽  
Mari ENDO ◽  
Tsutomu KOBAYASHI ◽  
Hiroki INOUE ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Rat Liver ◽  
Northern Blot Analysis ◽  
Glucuronic Acid ◽  
Liver Microsomes ◽  
Male Rat ◽  
Rat Liver Microsomes ◽  
Crystalline Compound ◽  
Udp Glucuronosyltransferase

Bisphenol A, an environmental oestrogenic chemical, was found to conjugate highly with glucuronic acid in male rat liver microsomes studied in vitro. In the various isoforms tested (1A1, 1A3, 1A5, 1A6, 1A7 and 2B1), glucuronidation of bisphenol A and of diethylstilboestrol, a synthetic crystalline compound possessing oestrogenic activity and known to be glucuronidated by liver microsomes, was catalysed by an isoform of UDP-glucuronosyltransferase (UGT), namely UGT2B1, which glucuronidates some endogenous androgens. UGT activity towards bisphenol A in liver microsomes and in UGT2B1 expressed in yeast AH22 cells (22.9 and 0.58 nmol/min per mg of microsomal proteins respectively) was higher than that towards diethylstilboestrol (75.0 and 4.66 pmol/min per mg of microsomal proteins respectively). UGT activities towards both bisphenol A and diethylstilboestrol were distributed mainly in the liver but were also observed at substantial levels in the kidney and testis. Northern blot analysis disclosed the presence of UGT2B1 solely in the liver, and about 65% of the male rat liver microsomal UGT activities towards bisphenol A were absorbed by the anti-UGT2B1 antibody. These results indicate that bisphenol A, in male rat liver, is glucuronidated by UGT2B1, an isoform of UGT.

scholarly journals Evidence for an UDP-glucuronic acid/phenol glucuronide antiport in rat liver microsomal vesicles

1996 ◽  
Vol 315 (1) ◽  
pp. 171-176 ◽  
Author(s):  
Gábor BÁNHEGYI ◽  
László BRAUN ◽  
Paola MARCOLONGO ◽  
Miklós CSALA ◽  
Rosella FULCERI ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Glucuronic Acid ◽  
Udp Glucuronosyltransferase ◽  
Luminal Compartment ◽  
Loading Procedure ◽  
Stimulation Of

The transport of glucuronides synthesized in the luminal compartment of the endoplasmic reticulum by UDP-glucuronosyltransferase isoenzymes was studied in rat liver microsomal vesicles. Microsomal vesicles were loaded with p-nitrophenol glucuronide (5 mM), phenolphthalein glucuronide or UDP-glucuronic acid, by a freeze–thawing method. It was shown that: (i) the loading procedure resulted in millimolar intravesicular concentrations of the different loading compounds; (ii) addition of UDP-glucuronic acid (5 mM) to the vesicles released both intravesicular glucuronides within 1 min; (iii) glucuronides stimulated the release of UDP-glucuronic acid from UDP-glucuronic acid-loaded microsomal vesicles; (iv) trans-stimulation of UDP-glucuronic acid entry by loading of microsomal vesicles with p-nitrophenol glucuronide, phenolphthalein glucuronide, UDP-glucuronic acid and UDP-N-acetylglucosamine almost completely abolished the latency of UDP-glucuronosyltransferase, although mannose 6-phosphatase latency remained unaltered; (v) the loading compounds by themselves did not stimulate UDP-glucuronosyltransferase activity. This study indicates that glucuronides synthesized in the lumen of endoplasmic reticulum can leave by an antiport, which concurrently transports UDP-glucuronic acid into the lumen of the endoplasmic reticulum.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Effects of Hypophysectomy on the Fine Structure of Rat Liver Cells

1967 ◽  
Vol 25 ◽  
pp. 156-157
Author(s):  
Robert R. Cardell
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Rat Liver ◽  
Liver Cell ◽  
Anterior Pituitary ◽  
Liver Cells ◽  
Biochemical Studies ◽  
Liver Functions ◽  
Rat Liver Cells ◽  
And Control

Hypophysectomy of the rat renders this animal deficient in the hormones of the anterior pituitary gland, thus causing many primary and secondary hormonal effects on basic liver functions. Biochemical studies of these alterations in the rat liver cell are quite extensive; however, relatively few morphological observations on such cells have been recorded. Because the available biochemical information was derived mostly from disrupted and fractionated liver cells, it seemed desirable to examine the problem with the techniques of electron microscopy in order to see what changes are apparent in the intact liver cell after hypophysectomy. Accordingly, liver cells from rats which had been hypophysectomized 5-120 days before sacrifice were studied. Sham-operated rats served as controls and both hypophysectomized and control rats were fasted 15 hours before sacrifice.

Sign in / Sign up

Export Citation Format

Share Document