Effect of diabetes mellitus induced by streptozotocin on renal Superoxide dismutases in the rat

Two forms of superoxide dismutase, CuZn-SOD and MnSOD, have been investigated in the kidneys of streptozotocin-induced diabetic rats using both radio-immunoassay and immunoenzyme staining. The rats were killed 2, 8 and 12 weeks after the induction of diabetes mellitus and the kidneys excised. Two weeks after the induction of diabetes, the kidneys were hypertrophied because of the proliferation of renal tubular epithelium. However, the total CuZnSOD content of the kidneys did not increase and, because of the epithelial proliferation, the CuZnSOD concentration in each proximal tubular cell was decreased. Armanni-Ebstein lesions were found in the distal tubules 8 and 12 weeks after the induction of diabetes. The cells in these lesions were intensely stained for CuZnSOD, suggesting an adaptive response to the enhanced oxidative stress. The MnSOD staining in the thick ascending limbs of Henle's loops was enhanced in the diabetic kidneys, while that in the cortical tubules was unaltered. MnSOD was assumed to increase in response to hypermetabolism associated with the proliferation of renal tubules. This was most marked in the cells which were rich in mitochondria, again suggesting an adaptive response to enhanced oxidative stress induced by diabetes mellitus. The glomeruli of both the diabetic and control groups were not stained for SODs, and no significant microscopic change was found even 12 weeks after the induction of diabetes mellitus.     

Simultaneous formation of menaquinones and demethylmenaquinones byMicrococcus varians IAM 12146 depending on cell growth media

Changes in the isoprenoid quinone composition ofMicrococcus varians IAM 12146 in response to growth in different media were investigated. When the bacterium was growth in an ordinary complex medium, it produced menaquinones as the sole quinones, with a dihydrogenated menaquinone with seven isoprene units as the major component, at all growth stages. On the other hand, cells grown in a chemically defined medium containing glutamate and pyruvate as carbon sources produced both menaquinones and demethylmenaquinones. The major demethylmenaquinone homologs produced were the unsaturated and dihydrogenated types with seven isoprene units. The demethylmenaquinone/menaquinone ratio in cells varied during a batch growth in the chemically defined medium. The highest ratio was found in cells at the mid-exponential phase of growth.     

Cloning and expression of cDNAs from enterically-transmitted non-A, non-B hepatitis virus.

The fragment gene of enterically-transmitted non-A, non-B hepatitis virus (ET-NANBHV) was cloned as a cDNA and inserted into an expression vector pUEX2. The recombinant protein was expressed in Escherichia coli HB101 as a fusion protein with beta-galactosidase (beta-Gal). The fusion protein reacted with the sera of infected cynomolgus monkeys and of patients from Myanmar. This reaction was highly related with ET-NANBHV infection, and obviously demonstrates in that the recombinant protein can be used for the detection of ET-NANBHV infection.     

Changes in conformation of spin-labeled calmodulin by phospholipids

Spin-labeled calmodulin was synthesized and the effects of phospholipids on its conformation were examined by ESR spectroscopy. Phosphatidylserine (0.1-1.0 mM) increased the signal intensity of the ESR spectrum of spin-labeled calmodulin and decreased the apparent rotational correlation time in the presence of 0.1 mM CaCl2. This change was reversed by addition of excess calcium, and in the absence of calcium phosphatidylserine did not change the spectrum, suggesting that the change in spin-labeled calmodulin brought about by phosphatidylserine was not induced by a hydrophobic interaction of the two, but by inhibition of the binding of calcium to calmodulin. L-Serine and O-phospho-L-serine had no effect on the ESR signals of spin-labeled calmodulin. The effects of various other phospholipids were also examined. Their inhibitory activities were in the order phosphatidic acid greater than phosphatidylserine greater than phosphatidylglycerol = phosphatidylinositol; phosphatidylethanolamine and phosphatidylcholine had no effect on the spectra. The effects of these phospholipids were dependent on their binding activities toward calcium. Furthermore, phosphatidic acid and phosphatidylserine at 1 mM reduced the activity of calmodulin-dependent phosphodiesterase by 16.4 and 8.7%, respectively. These findings indicate that spin-labeled calmodulin did not interact with the phospholipids by a hydrophobic interaction, but that calcium binding to spin-labeled calmodulin interfered with phosphatidic acid, phosphatidylserine, phosphatidylglycerol and phosphatidylinositol, and some of these phospholipids inactivated calmodulin. Thus the activity of calmodulin may be regulated in part by some phospholipids.     

High efficiency gene transfer into murine T cell clones using a retroviral vector

To establish a gene transfer and expression system for murine T cell clones, we have introduced the neomycin phosphotransferase gene encoding resistance to the neomycin analogue, G418, into non-neoplastic inducer T cell clones by using a replication-defective retroviral vector. This method allowed highly efficient gene transfer (20 to 40%) into two inducer T cell clones. The level of viral RNA expression in G418r T cells was 0.1% of poly(A)+ RNA. The infected G418r cells retained physiologic responsiveness to specific antigen as judged by antigen-specific proliferation and production of IL 3.     

Monoclonal antibody against non-histone chromosomal protein high mobility group 1 Co-migrates with high mobility group 1 into the nucleus

Non-histone chromosomal protein high mobility group 1 (HMG-1) rapidly migrates into the nucleus when injected into the cytoplasm of bovine fibroblasts and HeLa cells by red cell-mediated microinjection (Rechsteiner, M., and Kuehl, L. (1979) Cell 16, 901-908). We isolated hybridomas secreting monoclonal antibodies against HMG-1. One of these monoclonal antibodies, FR-1, inhibited in vitro binding of 125I-HMG-1 to chromatin isolated from FL cells. When 125I-HMG-1 was co-introduced with antibody FR-1 by red cell-mediated microinjection, antibody FR-1 did not prevent the accumulation of 125I-HMG-1 in the nucleus. When 125I-antibody FR-1 or fluorescein isothiocyanate antibody FR-1 was introduced into the cytoplasm of FL cells, most of the antibody did not accumulate in the nucleus. But when 125I- or fluorescein isothiocyanate antibody FR-1 was co-introduced with HMG-1 into the cytoplasm of FL cells, it did migrate into the nucleus.     

4-Hydroxyaminoquinoline 1-oxide metabolism and DNA adducts in the early stage of tumorigenesis in rats: comparison of target organ pancreas with non-target organ liver

In order to probe key early molecular events which might be responsible for the initiation of rat pancreatic tumorigenesis by 4-hydroxyaminoquinoline 1-oxide (4-HAQO), the uptake and metabolism of carcinogen and the formation and subsequent repair of DNA adducts were monitored under conditions of high and low tumorigenicity, respectively in partially pancreatectomized and non-operated animals, and in the liver, a non-target organ for this carcinogen. Although uptake of radioactively labelled 4-HAQO was higher in the liver than in the pancreas, generation of DNA adducts was 20 times greater in the latter organ. This discrepancy was probably due to a difference in the metabolic profile of 4-HAQO. The spectrum of the adducts was qualitatively similar in both organs. No qualitative or quantitative differences could be established under the high and low tumorigenicity conditions with regard to DNA adduct formation or persistence. The major difference was the presence of a relatively large extent of pancreatic DNA replication under the high tumorigenic condition. The results indicated that metabolic profile of 4-HAQO, quantity of DNA adducts and levels of DNA replication are key factors involved in initiation of tumorigenesis.     

DNA sequencing of the Escherichia coli ribonuclease III gene and its mutations

Summary A 0.7 kb DNA fragment of the Escherichia coli K12 chromosome was shown to contain the structural gene for RNAse III (rnc). The DNA sequence of the gene was determined and its alteration in an RNAse III defective mutant, AB301-105, was identified. DNA sequence analysis also showed that a secondary-site suppressor of a temperature-sensitive mutation in the E. coli ribosomal protein gene, rpsL, occurred within the rnc gene, providing genetic evidence for the interaction of ribosomal proteins with RNAse III, which in turn acts on the nascent ribosomal RNA during assembly of ribosomes in E. coli.     

Suppressors of temperature-sensitive mutations in a ribosomal protein gene, rpsL (S12), of Escherichia coli K12

Summary Temperature-sensitive (ts) mutations were isolated within a ribosomal protein gene (rpsL) of Escherichia coli K12. Mutations were mapped by complementation using various transducing phages and plasmids carrying the rpsL gene, having either a normal or a defective promoter for the rpsL operon. One of these mutations, ts118, resulted in a mutant S12 protein which behaved differently from the wild-type S12 on CM-cellulose column chromatography. Suppressors of these ts mutations were isolated and characterized; one was found to be a mutation of a nonribosomal protein gene which was closely linked to the RNAase III gene on the E. coli chromosome. This suppressor, which was recessive to its wild-type allele, was cloned into a transducing phage and mapped finely. A series of cold-sensitive mutations, affecting the assembly of ribosomes at 20°C, was isolated within the purL to nadB region of the E. coli chromosome and one group, named rbaA, mapped at the same locus as the suppressor mutation, showing close linkage to the RNAase III gene.