scholarly journals ON THE RELATIONSHIP OF LIVER GLUCOSE-6-PHOSPHATASE TO THE PROLIFERATION OF ENDOPLASMIC RETICULUM IN PHENOBARBITAL INDUCTION

1966 ◽  
Vol 31 (2) ◽  
pp. 243-256 ◽  
Author(s):  
Sten Orrenius ◽  
Jan L. E. Ericsson
Keyword(s):  
Endoplasmic Reticulum ◽  
Phosphatase Activity ◽  
Actinomycin D ◽  
Microsomal Enzymes ◽  
High Drug ◽  
Histochemical Methods ◽  
Relationship Of ◽  
The Relationship ◽  
Phenobarbital Induction ◽  
Liver Microsomal Enzymes

The differentiated effects of phenobarbital treatment on liver microsomal enzymes have been further studied. The relationship between the resulting decrease in the specific glucose-6-phosphatase activity and the enhancement of formation of endoplasmic reticulum membranes with high drug-hydroxylating activity has been investigated with biochemical and histochemical methods. Biochemically and histochemically demonstrable glucose-6-phosphatase activity was found to be present in all endoplasmic reticulum membranes, including the phenobarbital-induced smooth-surfaced proliferates, even though there was an over-all decrease in activity. Actinomycin D did not inhibit the decrease in glucose-6-phosphatase activity. The findings are discussed with reference to the enzyme-membrane relationship in phenobarbital induction.

Role of estrogens in phenobarbital induction of liver microsomal enzymes

1975 ◽  
Vol 80 (3) ◽  
pp. 1043-1045
Author(s):  
P. V. Sergeev ◽  
N. N. Vedernikova ◽  
A. I. Maiskii ◽  
N. V. Shapoval ◽  
V. A. Volov
Keyword(s):  
Microsomal Enzymes ◽  
Phenobarbital Induction ◽  
Liver Microsomal Enzymes

Low-Km mannose-6-phosphatase as a criterion for microsomal integrity

1998 ◽  
Vol 76 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Bartholomew A Pederson ◽  
James D Foster ◽  
Robert C Nordlie
Keyword(s):  
Endoplasmic Reticulum ◽  
Structural Integrity ◽  
Kinetic Studies ◽  
Reliable Index ◽  
Single Mechanism ◽  
Induced Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Low K ◽  
Hydrolysis Of

The low-Km activity of mannose-6-phosphatase (Man-6-Pase) has been used for many years to measure the structural integrity of microsomes. Recently histone II-A has been shown to activate glucose-6-phosphatase (Glc-6-Pase) and Man-6-Pase activities. However, in contrast to detergents, this compound appears to activate without disrupting microsomal vesicles (J.-F. St-Denis, B. Annabi, H. Khoury, and G. van de Werve. 1995. Biochem. J. 310: 221-224). This suggests that Man-6-Pase latency can be abolished without disrupting microsomal integrity and that even normally microsomes may manifest some low-Km Man-6-Pase activity without being "leaky." We have studied the relationship of Man-6-Pase with microsomal integrity further by measuring the latency of several enzymes reported to reside within the lumen of endoplasmic reticulum. We have also correlated this latency with the microsomal permeability of substrates for these enzymes. We found that (i) lumenal enzymes have different degrees of latency when compared with each other, (ii) permeability, as determined via osmotically induced changes in light scattering, is not always consistent with enzymatic latency, (iii) increases in the hydrolysis of Glc-6-P and Man-6-P were not parallel when microsomes were treated with low but increasing concentrations of detergent, and (iv) kinetic studies suggest that mannose-6-phosphate is hydrolyzed by untreated microsomes by more than a single mechanism. We propose that Man-6-Pase is not a reliable index of the integrity of microsomes.Key words: glucose-6-phosphatase, mannose-6-phosphatase, microsomes, rat liver, intactness.

scholarly journals GLUCOSE-6-PHOSPHATASE IN THE SALIVARY GLANDS OF SCIARA COPROPHILA: A HISTOCHEMICAL AND BIOCHEMICAL STUDY

1965 ◽  
Vol 13 (3) ◽  
pp. 168-181 ◽  
Author(s):  
JACOB Y. TERNER ◽  
REBA M. GOODMAN ◽  
DAVID SPIRO
Keyword(s):  
Endoplasmic Reticulum ◽  
Phosphatase Activity ◽  
Biochemical Study ◽  
Minimal Amount ◽  
Prolonged Incubation ◽  
Larval Stages ◽  
Larval Salivary Gland ◽  
Mammalian Liver ◽  
Specific Proteins ◽  
Relationship Of

Biochemical characteristics of an enzyme in larval stages of Sciara coprophila specifically hydrolyzing glucose-6-phosphate are shown to parallel those of a similar enzyme in mammalian liver with respect to substrate specificity and reactivity in the presence of various inhibitors. Even with prolonged incubation this enzyme can be demonstrated histochemically in unfixed larval salivary gland of Sciara coprophila only in focal dilated cisternae of the rough surfaced endoplasmic reticulum. It was concluded that the morphologically homogeneous microsomal system may have areas of biochemical specialization which allow the production of specific proteins (in this case a glucose-6-phosphatase) made in no other portion of the rough surfaced endoplasmic reticulum. Glucose-6-phosphatase activity is absent biochemically during the 2nd and 3rd instars. A minimal amount is present in the 4th instar and a marked elevation occurs prior to pupation; this level is maintained during pupation. Histochemically, glucose-6-phosphatase activity can be demonstrated throughout the larval stage. The relationship of the characteristic 4th instar puffs of dipteran larval chromosomes to the onset of high levels of glucose-6-phosphatase activity is discussed.

Small nuclear RNAs: an association with condensed chromatin in amoebae

1978 ◽  
Vol 30 (1) ◽  
pp. 227-235
Author(s):  
L. Goldstein ◽  
G.E. Wise ◽  
C. Stephenson ◽  
C. Ko
Keyword(s):  
Electron Microscopy ◽  
Actinomycin D ◽  
Condensed Chromatin ◽  
Nuclear Transplantation ◽  
Chromatin Binding ◽  
Binding Agent ◽  
Small Nuclear Rnas ◽  
Relationship Of ◽  
The Relationship ◽  
Mitotic Cells

For the purpose of studying the relationship of small nuclear RNAs (snRNAs) to chromatin, we studied the effect of the chromatin-binding agent actinomycin D (AMD) on the nuclei of amoebae. By electron microscopy we noted that when mitotic cells were placed in AMD their chromatin was highly condensed 3 h later. This contrasts strikingly with the situation in untreated cells, in which the chromatin at the same time is largely decondensed. After arranging, by nuclear transplantation of labelled nuclei into unlabelled cytoplasm, for the only labelled molecules in the cell to be 3H-snRNAs, we noted that in such cells similarly treated with AMD the labelled material was clustered in a form quite similar to that of the chromatin in 3-h post-division, AMD-treated cells. In untreated cells the 3H-snRNAs were distributed essentially uniformly throughout the nucleus. These observations, together with earlier findings that snRNAs associate with chromosomes during mitosis, lead us to conclude that snRNAs have a particular affinity for condensed chromatin.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

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