Effect Of Ricin Research Articles

A Review of Extraction and Detection of Ricin from Castor Plant and the Effect of Ricin on Humans

Ricin is a ribosome inactivating protein produced within the seeds of the castor oil plant (Ricinus communis). Ricin can be extracted from the mash of crushed castor seeds using different procedures. Ricin has 2 chains, the A chain and the B chain. It is extremely potent to mammals, being able to kill 1500 cells per minute in small doses. Castor bean plants are grown as an ornamental plant and are found in most households in parks around India, eastern Africa, and the south-eastern Mediterranean Basin. Methods of detection for ricin have been found, but not one that takes into account its presence in biological fluids. Ricin has also been found to be an immunotoxin against cancer, and it could be used as a medication in the future.

Intracellular Transport of Ribosome-Inactivating Proteins Depends on Annexin 13.

In the present study, we assessed the role of annexin 13 membrane-binding protein (ANXA13) in the intracellular transport of vesicles containing type II ribosome-inactivating proteins (RIP-IIs). A modified human intestinal epithelial cell line HT29 was used, in which the expression of ANXA13 was significantly reduced. The cytotoxic effect of ricin and viscumin was evaluated by modification of 28S ribosome RNA. The observed differences in the activity of toxins on the parental and modified HT29 lines indicate that ANXA13 plays a different role in the intracellular transport of vesicles containing the RIP-IIs.

Effect of ricin on photodynamic damage to the plasma membrane

Effect of ricin on photodynamic damage to the plasma membrane

Effect of Ricin on Some Biochemical, Haematological, and Histopathological Variables in Mice

Acute toxicity studies of ricin were carried out in Swiss albino male mice. The median lethal concentration (LD,,) values were determined for mice through intraperitoneal and oral routes and were found to be 1.01 ~ g l k gan d 28.29 mglkg, respectively. The ricin (1.0 LD,d was administered in mice through intraperitoneal route and various toxicity-related clinical var~ables were studied on the I, 3'd, and the 7 day of post-exposure. The prominent symptoms before death, were diarrhoea with black sticky vent and piloerection. The body weight decreased significantly in a dose-dependent manner. No significant change was observed in organ-to-body weight ratio on the 1. 3d, and the 7th day of post-exposure except kidney weight. On the 71h day, kidney weight increased significantty. The levels of bloodurea, uric acid, and glucose increased, while total protein level decreased. However, activities of transaminase and phosphatases were not altered. Leukocytosis was also observed. The ricin also affected blood coagulation parameters. There was a significant increase in the clotting time. However, prothrombin time, bleeding time, and erythrocyte sedimentation rate were not altered. Histopathological studies showed degenerative changes in various visceral organs, viz, lungs, liver, spleen, kidney, and testis. Acute toxicity studies of ricin revealed that it is a highly toxic toxin. The ricin intoxication caused alterations in biochemical, haematological variables, and degenerative changes in various visceral organs.

Effect of ricin and its B-subunit on calcium responses in human lymphocytes

The effect of ricin and its B-subunit on cytoplasmic Ca2+ concentration in human lymphocytes was studied using a fluorescence probe. Both agents dose-dependently increased cytosolic free Ca2+ by stimulating its release from of thapsigargin-sensitive store. It is suggested that this effect is associated with the increase in cytosolic content of inositol-1,4,5-trisphosphate.

The effect of ricin B chain on the intracellular trafficking of an A chain immunotoxin

Covalent linkage of the A chain of ricin to the LICR-LOND-Fib75 monoclonal antibody produced an immunotoxin, Fib75-SS-ricin A, which demonstrated immunospecific toxicity to human bladder carcinoma cells in tissue culture (Forrester et al., 1984). The present studies have shown that ricin B chain potentiates the toxicity of the immunotoxin by two orders of magnitude and also significantly increases the rate of protein synthesis inhibition. Using immunoelectron microscopy, the receptor-mediated endocytosis and intracellular routing of the immunotoxin was studied with and without ricin B chain treatment after immunolocalisation of the conjugate. Fib75-SS-ricin A was internalised by the EJ cells predominantly in uncoated pits and vesicles and directed to the endosomes. Some degradation of the complex appeared to take place in multivesicular endosomes at early timepoints and 24 h after internalisation, most of the immunotoxin was found in lysosomes. Some ricin A chain epitopes were detected in Golgi vesicles. Cells treated with immunotoxin and ricin B chain endocytosed the complex predominantly in coated pits and coated vesicles. Using pre-embedding immunoperoxidase techniques, ricin chains were found in the whole Golgi complex and most of the conjugate escaped lysosomal degradation. Internalised immunotoxin was recycled back to the plasma membrane in an active form associated with vesicles which appeared to be derived predominantly from multivesicular endosomes. A similar mode of recycling has recently been reported (McIntosh et al., 1990) for ricin holotoxin in the same cell line. These observations may explain the potentiating effect of toxin B chains in the antibody-directed targeting of toxin A chains.

Immuno-Enhancing Effects of Ricin

The effect of ricin on human peripheral blood mononuclear cells (PBMC) was tested in vitro. At low concentrations (10(-3) and 10(-4) micrograms/ml), ricin potentiated the effect of lipopolysaccharide to induce interleukin 1 (IL-1). Ricin was not mitogenic or co-mitogenic with phytohaemagglutinin or concanavalin A in PBMC cultures at low concentrations (less than 10(-4) micrograms/ml). Higher concentrations of ricin (greater than 10(-3) micrograms/ml) inhibited production of IL-1 by PBMC and the mitogen-driven proliferation of PBMC cultures.

The effect of ricin on the mixed function microsomal oxidase system in the rat liver

The effect of ricin on the mixed function microsomal oxidase system in the rat liver

Effect of ricin on the proliferation of rat spleen and mesenteric lymph node cells.

The effect of the castor bean toxin, ricin, on rat spleen and mesenteric lymph node cell cultures was tested. Rat lymphocytes were cultured for 2 days in the presence of optimal doses of the mitogens phytohaemagglutinin, conconavalin A, and lipopolysaccharide. At concentrations of 10(-3) to 10(-5) mg/ml ricin, spontaneous and mitogen-driven proliferation were inhibited. At lower concentrations, spleen but not mesenteric lymph node cells showed enhanced proliferation. Studies are continuing to identify subpopulations of lymphocytes with increased or decreased sensitivity to ricin and their role in the regulation of IgE.

The mechanism of the protein-synthesis elongation cycle in eukaryotes. Effect of ricin on the ribosomal interaction with elongation factors.

The functional significance of the post-translocation interaction of eukaryotic ribosomes with EF-2 was studied using the translational inhibitor ricin. Ribosomes treated with ricin showed a decreased rate of elongation accompanied by altered proportions of the different ribosomal phases of the elongation cycle. The content of ribosome-bound EF-2 was diminished by approximately 65% while that of EF-1 was unaffected. The markedly reduced content of EF-2 was caused by an inability of the ricin-treated ribosomes to form high-affinity pre-translocation complexes with EF-2. However, the ribosomes were still able to interact with EF-2 in the form of a low-affinity post-translocation complex. Ricin-treated ribosomes showed an altered ability to stimulate the GTP hydrolysis catalysed by either EF-1 or EF-2. The EF-1-catalysed hydrolysis was reduced by approximately 70%, resulting in a decreased turnover of the quaternary EF-1 X GTP X aminoacyl-tRNA X ribosome complex. In contrast, the EF-2-catalysed hydrolysis was increased by more than 400%, despite the lack of pre-translocation complex formation. The effect was not restricted to empty reconstituted ribosomes since gently salt-washed polysomes also showed an increased rate of GTP hydrolysis. The results indicate that the EF-1- and EF-2-dependent hydrolysis of GTP was activated by a common center on the ribosome that was specifically adapted for promoting the GTP hydrolysis of either EF-1 or EF-2. Furthermore, the results suggest that the GTP hydrolysis catalysed by EF-2 occurred in the low-affinity post-translocation complex.

Sensitivity of Preimplantation Mouse Embryos to Abrin

The effect of the plant toxin abrin on preimplantation mouse embryos in vitro was studied. Two-cell embryos from C57BL/6J or B6CBA/F1/Bom female X B6CBA/F1/Bom male mice were exposed to abrin for 72 hrs in vitro, in medium containing abrin in concentrations ranging from 0.1 to 10,000 pg/ml. Two-cell mouse embryos were also exposed to corresponding concentrations of ricin in vitro. The effect of abrin was evaluated by daily morphological observation of the embryos up to the blastocyst stage and by measuring DNA, RNA and protein synthesis by radioactive precursor incorporation. The effect of ricin was evaluated by morphological observation of the embryos up to the blastocyst stage. The results showed that 2-cell mouse embryos were highly sensitive to abrin, 1 pg/ml being the lowest concentration of the toxin that significantly inhibited the development of 2-cell embryos to the blastocyst stage. With ricin statistically significant inhibition of blastocyst formation was obtained at a concentration of 10 pg/ml. The ID50 for abrin was calculated to be 24 pg/ml and for ricin 47 pg/ml. A dose-dependent lag period was observed before the effect of abrin or ricin on the formation of blastocysts became evident. Incorporation of 3H-thymidine, 3H-uridine and 14C-leucine into DNA, RNA and protein, respectively, was also inhibited by abrin after different time intervals in culture.

Effects of ricin, a protein toxin, on glucose absorption by rat small intestine. Biochemical studies on oral toxicity of ricin. II.

The effects of ricin, a proteinous toxin from castor bean seeds, on glucose absorption by rat small intestine have been examined by the everted sac method. Glucose absorption was affected by ricin poisoning at 1 h after oral administration, and the inhibition reached the maximum at 5h, whereas very slight impairment of glucose absorption was observed at 5h after intraperitoneal injection of ricin. The dose required for 50% impairment of glucose absorption was 10mg ricin/kg body weight of rat when determined at 5 h after oral administration. This inhibition of glucose absorption was found only when ricin or ricin B-chain had been in contact with the mucosal membrane of the small intestine of the normal rats. The inhibition was prevented by the presence of a galactose-containing sugar, lactose. The effect of ricin on glucose absorption under physiological conditions was analyzed in situ, and the increase in blood glucose level was inhibited in ricin-intoxicated rats. These results suggest that ricin, especially its B-chain, interacts primarily with the intestinal mucosa and inhibits sugar absorption of the rat small intestine. It was also inferred that ricin B-chain is cytotoxic to the epithelial absorptive cells of the small intestine, but that impairment of sugar absorption by the small intestine alone is not the direct cause of death of animals following oral administration of ricin.

Effect of ricin, of its subunits and of modeccin on cAMP level in Yoshida ascites cells.

The B chain of ricin strongly decreases the PGE1-enhanced level of cAMP in Yoshida ascites sarcoma cells, whereas the A chain is ineffective. Modeccin does not have any effect.

Action on ricin and its polypeptide chains on cultured hepatoma cells.

The effect of ricin, the glycoproteic toxin from castor beans, as well as of its two polypeptide chains A and B, was studied on hepatoma tissue cell suspension cultures (HCT). The isolated A and B chains have no action. Ricin at a 0.3 microgram/ml concentration, for 3 x 10(5) cells/ml, has a cytostatic effect which becomes cytotoxic after 72 h. This effect exists even if the cells are preincubated for 4 with ricin and washed afterwards. The protein content of the ricin-treated cells decreases. Protein synthesis measured by the incorporation of [3H]-leucine in the cell proteins begins to be inhibited after 30 min and is completely blocked after 2 h for a ricin concentration of 0.3 microgram/ml. DNA synthesis is inhibited from 1 h on. Finally the level of the DNA slows down from 3 h on, whereas the level of RNA abruptly falls between 4 and 5 h. The inhibitory effects are likely to be a consequence of protein synthesis inhibition, but a direct effect on the nucleic acids is not excluded.

Effect of ricin on biosynthesis of myeloma protein (IgA) and general cellular proteins in MOPC-315 cells

Ricin, a phyto-toxin from the seeds of Ricinus communis, preferentially inhibits synthesis of myeloma protein by MOPC-315 cells as compared to the synthesis of general proteins. In contrast, cycloheximide inhibited equally both myeloma protein synthesis as well as general protein synthesis. These results suggest that proteins synthesized near or on cell membranes are more sensitive to Ricin which binds to the acceptor molecule on the plasma membrane.

The effect of ricin on the ultrastructure of the kidney

The effect of ricin on the ultrastructure of the kidney was investigated in albino rats. During ricin intoxication the ultrastructural changes of the kidney corresponded to the laboratory finding of proteinuria.