Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Ricinus”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2003

Changes in the expression pattern of the plasma membrane H+-ATPase in developing Ricinus communis cotyledons undergoing the sink/source transition.

The plasma membrane (PM) H+-ATPase is thought to play a key role in generating the proton motive force used to drive the uptake and accumulation of solutes in plant cells. Changes in its expression pattern were studied in the Ricinus communis L. cotyledon as it changed from a sink to a source organ. Expression was monitored in 3-, 10- and 14-day-old cotyledons using an antibody to the maize PM H+-ATPase. The antibody labelled a 100-kDa protein in membrane fractions prepared from cotyledons and this protein occurred at higher levels in the PM-enriched fractions compared to those enriched in intracellular membranes. Immunostaining of tissue sections of 3-day-old Ricinus cotyledons (sinks) with this antibody demonstrated that the PM H+-ATPase was highly expressed in the lower epidermal cells and also in the vascular bundles, particularly the phloem. The high expression in the epidermis suggests that these cells may be important in the initial active uptake of solutes from the endosperm. A similar distribution was observed in the 10-day-old seedlings but, in addition, larger, more spherical cells (idioblasts) had developed in the lower and upper epidermal layers and these were also labelled. In 14-day-old seedlings the cotyledons are no longer reliant on nutrients from the endosperm (which has totally degraded) and they are functioning as source organs. This is reflected in a decrease in PM H+-ATPase expression in the lower epidermal cells, apart from idioblasts and stomatal guard cells. The latter were also observed in the upper epidermis. Expression remained high in the vascular bundles of 14-day-old seedlings with strong staining in the phloem.

Cell Membrane↗
PubMed2005

Adenosine stimulates anabolic metabolism in developing castor bean (Ricinus communis L.) cotyledons.

In previous experiments it was shown that Castor-bean (Ricinus communis) endosperm releases carbohydrates, amino acids and nucleoside derivatives, which are subsequently imported into the developing cotyledons (Kombrink and Beevers in Plant Physiol 73:370-376, 1983). To investigate the importance of the most prominent nucleoside adenosine for the metabolism of growing Ricinus seedlings, we supplied adenosine to cotyledons of 5-days-old seedlings after removal of the endosperm. This treatment led to a 16% increase in freshweight of intact seedlings within 16 h, compared to controls. Using detached cotyledons, we followed uptake of radiolabelled adenosine and identified 40% of label in solubles (mostly ATP and ADP), 46% incorporation in RNA and 2.5% in DNA, indicating a highly active salvage pathway. About 7% of freshly imported adenosine entered the phloem, which indicates a major function of adenosine for cotyledon metabolism. Import and conversion of adenosine improved the energy content of cotyledons as revealed by a substantially increased ATP/ADP ratio. This effect was accompanied by slight increases in respiratory activity, decreased levels of hexose phosphates and increased levels of fructose-1,6-bisphosphate and triose phosphates. These alterations indicate a stimulation of glycolytic flux by activation of phosphofructokinase, and accordingly we determined a higher activity of this enzyme. Furthermore the rate of [(14)C]-sucrose driven starch biosynthesis in developing castor-bean is significantly increased by feeding of adenosine. In conclusion, our data indicate that adenosine imported from mobilizing endosperm into developing castor-bean cotyledons fulfils an important function as it promotes anabolic reactions in this rapidly developing tissue.

Adenosine↗
PubMed1984

Enolase isozymes from Ricinus communis: partial purification and characterization of the isozymes.

The plastid and cytosolic isozymes of enolase from developing endosperm of castor oil seeds, Ricinus communis L. cv. Baker 296, were separated and partially purified. Each purified isozyme had a specific activity of approximately 200 mumol min-1 mg protein. The isozymes have similar pH optima for the forward reaction, but different optima for the reverse reaction. The divalent metal specificity is the same for both isozymes. In addition to differences in charge, the isozymes can be distinguished by their different kinetic constants, thermostability, and sensitivity to fluoride inhibition. Antibodies against yeast enolase isozyme I cross-react with Ricinus plastid enolase but not with the cytosolic isozyme.

Cations, Divalent↗
PubMed1975

A quantitative assay for concanavalin A- and Ricinus communis agglutinin-mediated agglutinations of rat ascites hepatoma cells. Relationship between concanavalin A binding and cell agglutination.

A simple quantitative assay method was developed for the agglutination of rat ascites hepatoma cells mediated by Concanavalin A or Ricinus communis agglutinin. This method was based on the principle that the turbidity of a cell suspension is proportional to the sum of the cross-sectional area of cells and aggregatesmas predicted by the theoretical consideration, the turbidity decreased when cells were aggregated and the decrease was a function of the average number of the cells in aggregates. The agglutinability of the cells, judged by this method, showed a maximum value at a certain concentration of the agglutinin. By further addition of the agglutinin, the agglutinability slightly decreased from the maximum. These phenomena were observed both for Concanavalin A and Ricinus communis agglutinin. The binding and the agglutination experiments using [3-H]concanavalin A revealed that the binding to approx;0% of the total receptors caused a maximal agglutination. This suggested that the receptors responsible for the agglutination constitute only a small part of the total receptors on the surface.

Agglutination Tests↗
PubMed2005

Anti-inflammatory and free radical scavenging activity of Ricinus communis root extract.

Anti-inflammatory and free radical scavenging activities of the methanolic extract of Ricinus communis (RCM) (Euphorbiaceae) Linn. root was studied in Wistar albino rats. The methanolic extract at doses 250 and 500 mg/kg p.o. exhibited significant (P<0.001) anti-inflammatory activity in carrageenan-induced hind paw edema model. The extract at the dose of 500 mg/kg p.o. also exhibited significant (P<0.001) anti-inflammatory activity in cotton pellet granuloma model. The methanolic extract showed significant free radical scavenging activity by inhibiting lipid peroxidation initiated by carbon tetrachloride and ferrous sulphate in rat liver and kidney homogenates. The extract enhanced free radical scavenging activity of stable radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH*), nitric oxide and hydroxyl radical in in vitro assay methods. The results of the study indicate that the methanolic extract of Ricinus communis root possess significant anti-inflammatory activity in acute and chronic inflammatory models in rats. The observed pharmacological activity may be due to the presence of phytochemicals like flavonoids, alkaloids and tannins present in the plant extract with various biological activities.

Animals↗
PubMed1998

Amino acid carriers of Ricinus communis expressed during seedling development: molecular cloning and expression analysis of two putative amino acid transporters, RcAAP1 and RcAAP2.

This study reports on the isolation of two putative amino acid carrier cDNAs, RcAAP1 and RcAAP2, from Ricinus communis. Northern analysis shows that RcAAP1 and RcAAP2 are expressed abundantly in the cotyledon and root tissues of developing seedlings and at lower levels in the endosperm and hypocotyl. In the mature plant low expression was observed in the source and sink leaves. We have further characterized the expression of RcAAP1 in Ricinus roots by in situ hybridization. The transcripts are localized in many cell types of the root tip region, including the epidermal and cortical cells, but the highest expression was observed in the cells of the stele situated adjacent to the xylem poles. This is the first report describing the cellular expression of an amino acid transporter in roots, and the results are discussed in relation to the physiological role of this transporter.

Amino Acid Sequence↗
PubMed1979

Binding of Ricinus communis agglutinin to the mitochondrial inner membrane as an artifact during preparation.

Endosperm from Ricinus communis was homogenized in the presence of 3H-labelled Ricinus communis agglutinin, with or without addition of lactose. In preparations without the binding-specific sugar the subfraction containing the mitochondrial inner membrane contained sufficient labelled agglutinin to account for the agglutinin reported to be associated with this membrane.

Ricinus communis↗
PubMed1976

Interactions between ricinus agglutinin and human IgA.

By affinity chromatography on Sepharose columns containing insolubilized ricinus agglutinin, all immunoglobulins of the IgA2 subclass and the polymers of IgA1 were retained and could be eluted with lactose. Monomeric IgA1 showed a more heterogeneous reaction with ricinus agglutinin. The major part was unretarded, whereas some of it was weakly bound to the column and could be eluted with lactose.

Chromatography, Affinity↗
PubMed1999

Antifertility activity of Ricinus communis seed in female guinea pigs.

OBJECTIVE: To investigate the anti-fertility effect of Ricinus communis seed extract. DESIGN: Laboratory-based experiment. SETTING: Laboratory of the Department of Pharmacology, Faculty of Medicine, Addis Ababa University, Addis Ababa, Ethiopia in 1996. RESULTS: The seed extract was found to possess anti-implantation and abortifacient effects. It was also observed that the seed extract prolonged the oestrus cycle of guinea pigs. The dioestrus phase was significantly prolonged as well. After stopping administering the extract, however, the normal dioestrus phase and oestrus cycle started to resume. The seed extract also reduced the weight of the uterus without affecting that of the ovaries significantly. CONCLUSION: Ricinus communis possesses an anti-fertility effect in female guinea pigs, which might be extrapolated in human beings. These findings might support the accredited claim of its traditional use to avoid unwanted pregnancies. Further studies, however, should be pursued.

Abortifacient Agents↗
PubMed1978

Extraction and partial purification of ricin from Ricinus communis L.

Ricinus communis L., usually cultivated for production of oil, has some use in medicine, cosmetic industries and as motor oil. The defatted seed meal is very toxic, and can not be used as human or animal food. This study undertook extraction and identification of ricin, a toxalbumine, from Iranian Ricinus communis L. Ricin, was extracted from the seeds using dilute acid solution, salted out with ammonium sulfate, and purified by Sephadex G - 75 and DEAE - cellulose column chromatography. Disc electrophoresis showed the degree of the purification. Ricin is an anti-tumor and allergenic compound. It is also useful in biochemical research in gene control and protein systhesis.

Animals↗
PubMed1995

Comparative toxicity of Ricinus communis and Jatropha curcas in Brown Hisex chicks.

Symptoms, lesions and changes in growth, haematology and clinical chemistry were investigated in Brown Hisex chicks fed diets containing 0.5% Jatropha curcas seed or 0.5% Ricinus communis seed. High mortality and more severe changes occurred in chicks on Ricinus diet than Jatropha feed. The results indicated that caution should be observed in tropical countries where people are accustomed to chewing castor bean when in need of a laxative.

Animal Feed↗
PubMed2001

Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks in Finland.

Approximately 20 cases of tick-borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Aland islands. Ixodes ricinus panels collected in 1996-1997 from two endemic areas were screened for the presence of RNA. Two distinct RT-PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 microl. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Aland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000-200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia.

Animals↗
PubMed2006

Optimization of the solid-phase microextraction method in the determination of Ixodes ricinus (L.) volatiles.

For the first time, headspace solid-phase microextraction coupled with GC-MS analysis was used to study volatile compounds emitted by the tick Ixodes ricinus (L.). Variables such as the type of SPME fibre, equilibration time and extraction time have been evaluated with the mixture of four selected standards, a so-called artificial tick (acetophenone, racemic 4-heptanolide, methyl 2-methoxybenzoate and methyl 3-chloro-4-methoxybenzoate). Optimized conditions were obtained by the use of polydimethylsiloxan 100 microm fibre at 30 min equilibration and 15 min extraction time. The method proved to have a good linearity (r2 >0.98) at a concentration range from 0.5 ng (1 ng for methyl 3-chloro-4-methoxybenzoate) to 25 ng. LODs for a compound ranged between 0.19 and 1 ng, RSD (%) ranged from 13.76 to 25.08. The determination of 1.99 ng of methyl 3-chloro-4-methoxybenzoate emitted by five engorged females proved the usefulness of the developed method to identify and quantify the volatile compounds emitted by I. ricinus ticks.

Animals↗
PubMedDate not supplied

Sites of attachment and density assessment of female Ixodes ricinus (acari: ixodidae) on dairy cows.

A sample of 110 lactating dairy cows was examined to describe the attachment sites of female Ixodes ricinus ticks and to assess whether counts on one or two body areas can predict infestation and its level. Seventy per cent of the cows were infested by I. ricinus and the average tick burden on the infested cows was 15, ranging from 1 to 136. Preferred attachment sites were the axilla, udder/groin, neck, dewlap and flank. Udder/groin and axilla carried respectively 35.3% and 44.1% of the total tick burden. To predict infestation (yes/no), sensitivity of counts on axilla, on udder/groin and on both areas was respectively, 76.6%, 80.6% and 94.8%. Total burden prediction equations based on count on axilla and udder/groin are presented.

Animals↗
PubMed1995

Entomopathogenic fungi associated with Ixodes ricinus ticks.

The objective of this study was to demonstrate the occurrence of entomopathogenic fungi on Ixodes ricinus ticks in relation to the tick stage, engorgement and season. Ticks were collected from the vegetation, from small rodents and from deer. All entomopathogenic fungi found belonged to the Hyphomycetes. Paecilomyces farinosus and Verticillium lecanii were the predominant species. Other species, found only on engorged females were: Beauveria bassiana, B. brongniartii, P. fumosoroseus and V. aranearum. Eight out of 1833 ticks collected from the vegetation and three out of 269 engorged nymphs were infected with fungi. Thirty-three out of 149 engorged females were infected, whereas males and engorged larvae were not infected. Throughout the season, a significantly higher proportion of ticks collected in autumn were infected. Entomopathogenic fungi may have a significant impact on the size of the I. ricinus population, since females were the most frequently infected stage.

Animals↗
PubMed1996

Prevalence of Borrelia burgdorferi (sensu lato) in Ixodes ricinus (L.) populations in France, according to a phytoecological zoning of the territory.

Ixodes ricinus is considered as the main vector of Lyme Borreliosis in France. The aim of our investigations was to obtain a comprehensive view of the spatial risk linked to the distribution of the species in our country. Previous studies [1] have provided strong evidence that the species populations are widely distributed, so the objective of the present work was to ascertain the bacteriological infection of the tick by the agent of the zoonosis (Borrelia burgdorferi, sensu lato), over the French territory, whatever the ecological conditions may be. For this purpose, we kept the same framework as that used in our acarological investigation, a phytoecological zoning of the territory into 54 geographically separate and ecologically distinct units distributed into three climatic zones. Batches of ticks, picked up in these different phytoecological units (only two thirds of which were sampled), were submitted for bacteriological investigation. A total of 4,673 ticks were examined, individually, for the presence of Borrelia burgdorferi, by immunofluorescence. Percentages of infection according to the various stages of Ixodes ricinus free stages, collected by flagging, were as follows: 4.95% in 3,247 nymphs, 11.2% in 699 males, 12.5% in 727 females. Larvae were ignored. Practically all the tested units harboured the bacterium. The percentage of tick samples (25 ticks or more) absolutely free of Borrelia, wherever they came from, is very low (not exceeding 10 percent of the sampled forests). Our study confirms the assessment of a widespread distribution of the zoonosis in France which was, until now, exclusively based on an approximate distribution of limited human cases observed in the country.

Animals↗
PubMed1989

Effects of cyclosporin A on humoral immunity to ticks and on cutaneous immediate and delayed hypersensitivity reactions to Ixodes ricinus L. salivary-gland antigens in re-infested rabbits.

When rabbits are repeatedly infested with Ixodes ricinus L. adults, they acquire resistance to these ticks. A humoral response occurs and the skin of the host becomes progressively sensitized to the saliva of the ectoparasites. The present study examined the effects of cyclosporin A on these two aspects of immunity in re-infested rabbits. Using the enzyme-linked immunosorbent assay (ELISA), moderate suppression of the secondary IgG response to bites of these ticks was observed in animals given this immunosuppressive drug. The agent blocked the immediate cutaneous (type I) reaction normally developed in response to the intradermal injection of I. ricinus salivary gland antigens, as detected by measuring the skinfold thickness. The same method revealed a decreased delayed (type IV) hypersensitivity to these antigens. The present experiments demonstrate the major role of cyclosporin A-sensitive cells (mostly T-lymphocytes, mast cells and basophils) involved in the complex phenomenon of resistance to ticks.

Animals↗
PubMed1991

The peritrophic membrane of Ixodes ricinus.

A peritrophic membrane was found in all three stages of Ixodes ricinus at no later than 18 h after their placement on rabbits. It was found to remain intact until at least 11, 30 and 10 days after repletion in larvae, nymphs and females, respectively. In blood-feeding I. ricinus, the peritrophic membrane is an uneven single layer with a thickness of about 0.03-0.48 micron in larvae, 0.03-0.79 micron in nymphs and 0.04-0.93 micron in females. It covers the whole surface of the midgut epithelium at a distance of about 0.2-0.8 micron. After repletion, the peritrophic membrane becomes thicker and thicker and more and more winding and simultaneously becomes multi-layered mainly in its arched parts. The distance between the peritrophic membrane and the midgut epithelium increases considerably and in the arched parts can reach as much as about 13 and 16 microns in metamorphosing larvae and nymphs, respectively and 25 microns in ovipositing females.

Animals↗