Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ribonucleases are found in considerable quantities in the pancreas of a number of mammalian taxa and a few reptiles. The ribonuclease content varies greatly in different species. Large quantities are found in ruminants and species that have a ruminant-like digestion and in a number of species with coecal digestion. This is a response to the necessity of digesting large amounts of RNA derived from the microflora of the stomach of ruminants or species with ruminant-like digestion or of the coecum of species with coecal digestion. The amino acid sequence of pancreatic ribonuclease from the chromosomal species 2n = 60 of the mole rat, superspecies Spalax Ehrenbergi was determined. From the comparison of the sequence with those of other mammalian species we found that Spalax diverged from the myomorph rodent branch before the divergence of the Muridae (mouse, rat) from the Cricetidae (hamster, muskrat). Spalax ribonuclease shares several amino acid residues with other myomorph rodent species. These are not or only rarely observed outside this rodent suborder. Although the ribonuclease content varies greatly in different mammalian species, the variation in content between individuals within a species is small. Spalax is an exception to this with ribonuclease contents varying over more than an order of magnitude in different individuals. Ribonucleases isolated from the chromosomal species 2n = 52, 2n = 58 and 2n = 60 have identical elution positions on reversed-phase HPLC. The enzyme from the 2n = 54 species, however, elutes at a slightly earlier elution position. No amino acid sequence differences have been found hitherto between the ribonucleases of the four chromosomal species of Spalax ehrenbergi occurring in Israel. However, due to lack of material we were unable to determine more than about 20% of the sequence of the enzyme from the 2n = 54 species, which is the oldest offshoot.
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PMID:Ribonuclease in different chromosomal species of the mole rat, superspecies Spalax ehrenbergi: concentration in the pancreas and primary structure. 230 13

Some of the enzymes and metabolites of the glycolytic pathway of an animal model for cystic fibrosis (the chronically reserpine-treated rat) were investigated. The activities of the enzymes phosphofructokinase (P less than 0.002), enolase (P less than 0.03), pyruvate kinase (P less than 0.005), and lactate dehydrogenase (P less than 0.009) were decreased whereas the activity of glycerol-3-phosphate dehydrogenase was unaffected in the submandibular glands of the treated animals. For metabolites, the reserpine treatment resulted in an increased concentration of glycogen (P less than 0.0002) and phosphoenolpyruvate (P less than 0.001) and a decreased concentration of pyruvate (P less than 0.005) and lactate (P less than 0.002) in the glands. The concentration of glucose and glycerate-2-phosphate was unaffected. The perchloric acid-soluble part of the proteins was also increased (P less than 0.0001) in the submandibular glands of the reserpine-treated animals, as was the activity of ribonuclease. These findings point to a disturbance in the metabolism of glucose and a possible acidosis in the submandibular glands of this animal model for cystic fibrosis.
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PMID:The chronically reserpinized rat: decreased glycolytic activity in the submandibular gland. 399 4

Plagemann, Peter G. W. (Western Reserve University, Cleveland, Ohio), and H. Earle Swim. Replication of mengovirus. I. Effect on synthesis of macromolecules by host cell. J. Bacteriol. 91:2317-2326. 1966.-The replication of mengovirus was studied in two strains of Novikoff (rat) hepatoma cells propagated in vitro. The replicative cycle in both strains required 6.5 to 7 hr. Infection resulted in a marked depression of ribonucleic acid (RNA) and protein synthesis by strain N1S1-63. Inhibition of RNA synthesis was reflected by a decrease in the deoxyribonucleic acid (DNA)-dependent RNA polymerase activity of isolated nuclei. Mengovirus had no effect on either protein or RNA synthesis or on the DNA-dependent RNA polymerase activity of a second strain, N1S1-67. The time course of viral-induced synthesis of RNA by cells was studied in cells treated with actinomycin D. It was first detectable between 2.5 and 3 hr after infection and continued until 6.5 to 7 hr. The formation of mature virus was estimated biochemically by measuring the amount of RNA synthesized as a result of viral infection which was resistant to degradation by ribonuclease in the presence of deoxycholate. Approximately 70% of the deoxycholate-ribonuclease-resistant RNA was located in mature virus, and the remainder was double-stranded. The formation of mature virus began about 45 min after viral-directed (actinomycin-resistant) synthesis of RNA was detectable in the cell, and only about 18 to 20% of the total RNA synthesized was incorporated into virus. Release of virus from cells began about 1 hr after maturation was first detectable. Release of virus from cells was accompanied by a loss of a large proportion of their cytoplasmic RNA and protein.
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PMID:Replication of mengovirus. I. Effect on synthesis of macromolecules by host cell. 428 85

In situ hybridization is used for detection of RNA expression when conservation of tissue architecture is important. Most in situ hybridization protocols are written for tissues from animals (i.e., rat) which can be harvested and preserved rapidly. In contrast, human tissue is more difficult to obtain, hence in situ hybridization experiments must frequently be performed with less than optimal tissue preservation. This procedure details hybridization of a radiolabeled single-stranded RNA probe (riboprobe) to complementary sequences of cellular RNA in human tissue sections. This method enables detection of rare mRNA species in specific cell types of human tissue, offering distinct advantages over other in situ methods due to increased sensitivity. In particular, we have found that UV cross-linking and ribonuclease treatment protocols need to be altered for human tissues to ensure successful results, making this protocol unique to those previously described. In situ hybridization experiments can be performed using either DNA or RNA probes. RNA probes are advantageous since they form stable hybrids, are single-stranded, have little or no reannealing during hybridization, and can be synthesized to high specific activity. RNA probes can be readily created utilizing SP6, T3, or T7 promoters in both sense and antisense orientations to provide non-specific (control) and specific probes. Disadvantages of RNA riboprobes include a tendency for RNA to stick non-selectively more than DNA, and degradation by RNase (hence strict adherence to RNase-free precautions is mandatory during most of the protocol). The following protocol includes: (1) preparation of human tissues (tissue fixation and sectioning are highlighted as critical for probe penetration, preservation of tissue architecture, retention of tissue RNA, and overall success); (2) generation of radiolabeled riboprobes (total incorporation of radionucleotide is important to increase sensitivity; 35S was chosen as a compromise between excellent sensitivity, cellular resolution, and required exposure times (compared with 32P or 3H); non-isotopic methods have not been tested in a side-by-side comparison with 35S in human tissues by us, but theoretically might offer faster exposure times while maintaining high resolution); (3) hybridization conditions (stringency, temperature, washes, tissue dehydration); and (4) sample visualization (application of photographic emulsion, developing, fixing, staining, and counterstaining of individual slides).
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PMID:In situ hybridization: identification of rare mRNAs in human tissues. 938 82

Although ciliary neurotropic factor (CNTF) is a tropic factor in nervous system development and maintenance, peripheral administration of this cytokine also causes severe anorexia and weight loss. The neural mechanism(s) mediating the loss of appetite is not known. As hypothalamic neuropeptide Y (NPY) is a potent orexigenic signal, we tested the hypothesis that CNTF may adversely affect NPYergic signaling in the hypothalamus. Intraperitoneal administration of CNTF (250 microg/kg) daily for 4 days significantly suppressed 24-h food intake in a time-dependent manner and decreased body weight. The loss in body weight was similar to that which occurred in pair-fed (PF) rats. As expected, hypothalamic NPY gene expression, determined by measurement of steady state prepro-NPY messenger RNA by ribonuclease protection assay, significantly increased in PF rats in response to energy imbalance. However, despite a similar loss in body weight, there was no increase in NPY gene expression in CNTF-treated rats. Daily administration of CNTF intracerebroventricularly (0.5 or 5.0 microg/rat) also produced anorexia and body weight loss. In this experiment, negative energy balance produced by both PF and food deprivation augmented hypothalamic NPY gene expression. However, despite reduced intake and loss of body weight, no similar increment in hypothalamic NPY gene expression was observed in CNTF-treated rats. In fact, in rats treated with higher doses of CNTF (5.0 microg/rat), NPY gene expression was reduced below the levels seen in control, freely fed rats. Furthermore, CNTF treatment also markedly decreased NPY-induced feeding. These results suggested that anorexia in CNTF-treated rats may be due to a deficit in NPY supply and possibly in the release and suppression of NPY-induced feeding. The possibility that CNTF-induced anorexia may be caused by increased leptin was next examined. Daily intracerebroventricular injections of leptin (7 microg/rat) decreased food intake, body weight, and hypothalamic NPY gene expression in a manner similar to that seen after CNTF treatment. Leptin administration also suppressed NPY-induced feeding. However, peripheral and central CNTF injections markedly decreased leptin messenger RNA in lipocytes, indicating a deficiency of leptin in these rats; thus, leptin was unlikely to be involved in appetite suppression. Thus, these results show that a two-pronged central action of CNTF, causing diminution in both NPY availability and the NPY-induced feeding response, may underlie the severe anorexia. Further, unlike other members of the cytokine family, suppression of NPYergic signaling in the hypothalamus by CNTF does not involve up-regulation of leptin, but may involve a direct action on hypothalamic NPY neurons or on neural circuits that regulate NPY signaling in the hypothalamus.
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PMID:Anorectic effects of the cytokine, ciliary neurotropic factor, are mediated by hypothalamic neuropeptide Y: comparison with leptin. 944 12

A series of contiguous deletions were made in a cDNA encoding the ribonuclease restrictocin with the purpose of identifying the amino acids that are essential for the cleavage of the phosphodiester bond on the 3' side of G4325 in the alpha-sarcin/ricin domain of mammalian (rat) 28S rRNA. In all 93 of 149 amino acids, 62% of the residues in restrictocin, were not essential for the action of the toxin. Of the five residues that have been proposed to constitute the active site, three could be deleted without loss of activity if they were part of a deletion of three or five amino acids but not if they were removed singly. It is likely that the loss of these three residues is compensated for by a neighboring residue that occupies the structural space created by the larger amino acid deletions. This was demonstrated to be the case for the active site residue Glu95 which in the deletion mutant Delta91-95 is replaced by Asp90. Systematic deletion of amino acids is a rapid, cost effective method for identifying the residues in a protein likely to contribute directly to function and, hence, deserving of closer scrutiny. Moreover, a semiquantitative estimate of the contribution of the residue to function can be made. For this reason the method may be useful for functional proteomics.
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PMID:Analysis by systematic deletion of amino acids of the action of the ribotoxin restrictocin. 1182 14