Subcellular topology of rat liver methionyl-, leucyl-, and arginyl-tRNA synthetases.

We have investigated the distribution of methionyl-, leucyl-, and arginyl- tRNA synthetases in primary liver fractions obtained by differential centrifugation of homogenates in isotonic sucrose: 78-93% of synthetase activities are recovered in the cytosolic fraction. Microsomes contain only 4.8%, 19.

[Endoplasmic reticulum: anatomy of a biologic membrane].

Endoplasmic reticulum (ER) is a large membranous network containing a wide variety of lipid and protein constituents which play important roles in cellular physiology. In this review, selection of experimental results are presented which have shaped our concepts of the molecular organization of ER. The morphological approach--electron microscope examination of ultra-thin sections of a variety of cells--led to the dualistic distinction between rough ER and smooth ER.

Pathophysiology of peroxisomal beta-oxidation.

Mammalian peroxisomes are subcellular organelles involved in the metabolism of hydrogen peroxide (oxidases, catalase), lipid anabolism (ether lipid biosynthesis) and catabolism (oxidation of fatty acids and fatty acid derivatives), and intermediary metabolism (transaminases, dehydrogenases). Peroxisomes are formed by division, as is the case for mitochondria, but, in contrast to these organelles, they do not contain DNA. They were discovered and characterized (by biochemical and morphological techniques) later than the majority of the other cell components and specific procedures have been developed for their isolation.

Clinico-biochemical aspects of guanidine compounds in uraemic toxicity.

"Uraemia" literally means "urine in blood". With the advancement of basic medical sciences, it is being better understood. The clinical syndrome of uraemia is due to the failure of not only the excretory but also the metabolic, regulatory and endocrine functions of the kidney.

Analysis of cis- and trans-acting elements in the hormone-sensitive human somatotropin gene promoter.

The expression of the human growth hormone (hGH) gene is regulated by several transcription factors. Basal level transcription factors include TATA box-binding proteins, Sp1, USF and CTF/NF-1. The hGH gene is expressed only in pituitary somatotrophs, and the pituitary-specific GHF-1/Pit-1 protein is a potent transcriptional stimulator.

Subcellular fractionation of epithelial cells from toad urinary bladder. 2. Isopycnic centrifugation and effect of density perturbants.

Cytoplasmic granules obtained from toad urinary bladder epithelial cells were brought to buoyancy in a linear sucrose gradient. The gradient was loaded either with untreated cytoplasmic granules, or with granules treated with Na pyrophosphate (PPi), with digitonin, or with PPi and digitonin in succession. The following enzymes were assayed in the gradient subfractions: oligomycin-insensitive Mg++-ATPase, alkaline phosphodiesterase I, alkaline phosphatase, acid N-acetyl-beta-glucosaminidase, cytochrome oxidase, nucleoside diphosphatase (substrate, ADP), aminopeptidase (substrate, leucyl-beta-naphthylamide), and mannosyltransferase (acceptor, dolichylphosphate).

Comparative study of the effect of chrysotile, quartz and rutile on the release of lymphocyte-activating factor (interleukin 1) by murine peritoneal macrophages in vitro.

The release of lymphocyte-activating factor (LAF) into the medium of cultured mouse resident peritoneal macrophages was estimated from the effect of this medium on the proliferation of mouse thymocytes in the presence of phytohaemagglutinin. Untriggered macrophages released little LAF into their culture medium. Upon addition of UICC chrysotile A (25-50 micrograms/10(6) macrophages), LAF appeared in the medium, and release continued for at least 20 h.

Pathways and control of adenine nucleotide catabolism in anoxic rat hepatocytes.

Studies are reviewed that show that in isolated rat hepatocytes subjected to anoxia, the catabolism of AMP, leading to uric acid instead of to allantoin in normoxia, proceeds almost exclusively by deamination of AMP followed by dephosphorylation of IMP. Adenosine, which is nearly undetectable in normoxic cell suspensions, accumulates to a slight extent in anoxia. The regulatory properties of liver AMP deaminase and cytosolic IMP-GMP 5'-nucleotidase were found to provide protective mechanisms for the hepatic adenine nucleotide pool in hypoxia.

Comparative analysis of the genomes of intestinal spirochetes of human and animal origin.

The aim of the present work was to compare the genomes of 21 strains of intestinal spirochetes, which were isolated from patients suffering intestinal disorders, with those of Treponema hyodysenteriae (strain P18), the known etiological agent of swine dysentery (bloody scours), and of a nonpathogenic strain (M1) of Treponema innocens. The percent guanine-plus-cytosine value of the 23 DNAs was found to be 25.5 to 30.

Subcellular fractionation of epithelial cells from toad urinary bladder. 1. Assay of marker enzymes and differential centrifugation.

We have undertaken the analytical fractionation of epithelial cells from toad urinary bladder, a tissue extensively used to study epithelial transport of ions and water. In an attempt to establish markers for the main subcellular organelles, a number of enzymes were assayed in cell homogenates. The nearly ubiquitous plasma membrane marker 5'-nucleotidase, and the transferases that donate N-acetylglucosaminyl, galactosyl, and sialyl residues to glycoproteins and glycolipids in the Golgi complex were not detectable.

Comparison between the formation and the oxidation of dicarboxylylcarnitine esters in rat liver and skeletal muscle: possible implications for human inborn disorders of mitochondrial beta-oxidation.

The activity of dicarboxylyl-CoA synthetase previously reported in rat liver was detected, in the presence of added detergents, in rat skeletal muscle. In both tissues, carnitine dicarboxylyltransferase activities were recorded but their substrate chain length specificity was, however, different. In rat skeletal muscle, but not liver, a carnitine-dependent oxidation by intact mitochondria of dodecanedioyl-CoA was easily detected by the spectrophotometric measurement of the substrate-dependent ferricyanide reduction.

Activation of rat complement by soluble and insoluble rat IgA immune complexes.

The ability of rat monoclonal IgA, specific for 2,4-dinitrophenyl (DNA), to activate the complement (C) system of the rat was investigated using aggregated IgA or IgA immune complexes (IC). IgA was coated onto a solid phase, and tested for its capacity to bind C3 upon incubation at 37 degrees C in normal rat serum (NRS) in the presence of Mg-EGTA. Binding of C3 was observed dependent on the dose of dimeric (d-), polymeric (p-) and secretory IgA tested.

Comparison of the metabolism of dodecanedioic acid in vivo in control, riboflavin-deficient and clofibrate-treated rats.

Intravenous administration of dodecanedioate (or hexadecanedioate) to anaesthetized rats resulted in the urinary excretion of medium-chain dicarboxylic acids (adipic, suberic and sebacic acids). In control animals, the recovery of infused dodecanedioate in the form of urinary medium-chain dicarboxylic acids corresponded to 30% of the infused dose (22 mumol/100 g body mass). This excretion was markedly increased in riboflavin-deficient rats (75% of the infused dose) while it was severely decreased in clofibrate-treated animals (less than 5%).

Inhibition of steroid-protein interactions by dicyclohexane derivatives.

Sixteen dicyclohexane derivatives including the parent compound d,1-3,4-bis (4-oxocyclohexyl)-hexane (PRDX) have been synthesized and studied for putative interference with androgen binding to transport proteins, metabolizing enzymes, and receptors from rat tissues. Several of these analogues inhibited competitively the binding of dihydrotestosterone to ABP, the epididymal androgen transport protein. One compound had an affinity for ABP as high as Kd = 70 nM.

Cloning and sequencing of Pseudomonas genes encoding vanillate demethylase.

A 2,598-base-pair (bp) SalI-HincII DNA fragment has been cloned which codes for vanillate demethylase, the enzyme responsible for the demethylation of vanillate (3-methoxy-4-hydroxybenzoate) to protocatechuate (3,4-dihydroxybenzoate). Complementation and insertional inactivation experiments have shown that this fragment carries two genes (vanA and vanB) which are predominantly cotranscribed from a promoter upstream of vanA. Nucleotide sequencing of the SalI-HincII fragment confirmed the genetic data: two open reading frames of 987 and 942 bp were present in the transcribed orientation.

Receptors for the host low density lipoproteins on the hemoflagellate Trypanosoma brucei: purification and involvement in the growth of the parasite.

The slender bloodstream form of Trypanosoma brucei shows receptor-mediated endocytosis of low density lipoprotein (LDL) particles of its hosts. We have purified the LDL receptor of this species nearly to homogeneity (about 1000-fold purification) and obtained monospecific polyclonal antibodies against it. As analyzed by NaDodSO4/polyacrylamide gel electrophoresis, the purified receptor consists of a single subunit, with an apparent molecular mass of 86 kDa.

Analysis of human lymphocyte protein expression. I. Identification of subpopulation markers by two-dimensional polyacrylamide gel electrophoresis.

This study provides new knowledge on the changes in protein expression that differentiate the functionally and phenotypically different cells of the human immune system. Purification by flow cytometry of normal lymphocytes (both T and B cells), monocytes and granulocytes, combined with high-resolution two-dimensional polyacrylamide gel electrophoresis, revealed reproducible qualitative and quantitative changes between these cell populations. Characteristic profiles of marker proteins for each cell type were identified.

Demonstration of glycosomes (microbodies) in the Bodonid flagellate Trypanoplasma borelli (Protozoa, Kinetoplastida).

Homogenates of Trypanoplasma borelli were subjected to subcellular fractionation by sequential differential and isopycnic centrifugation in sucrose. Glycerol-3-phosphate dehydrogenase and the glycolytic enzymes, glucosephosphate isomerase and triosephosphate isomerase, as well as the peroxisomal marker enzyme catalase were mainly, or in part, associated with sedimentable particles that had a buoyant density in sucrose of 1.22 g cm-3.