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At least 73 records · Page 4Linked to original sources
PubMed2006

psbA mutation (Asn266 to Thr) in Senecio vulgaris L. confers resistance to several PS II-inhibiting herbicides.

DNA sequence analysis of the psbA gene encoding the D1 protein of photosystem II (PS II), the target site of PS II-inhibiting herbicides, identified a point mutation (Asn266 to Thr) in a bromoxynil-resistant Senecio vulgaris L. population collected from peppermint fields in Oregon. Although this mutation has been previously reported in Synechocystis, this is the first report of this particular point mutation in a higher plant exhibiting resistance to PS II-inhibiting herbicides. The resistant population displayed high-level resistance to bromoxynil and terbacil (R/S ratio 10.1 and 9.3, respectively) and low-level resistance to metribuzin and hexazinone (R/S ratio 4.2 and 2.6, respectively) when compared with the susceptible population. However, the population was not resistant to the triazine herbicides atrazine and simazine or to the urea herbicide diuron. A chlorophyll fluorescence assay confirmed the resistance levels and patterns of cross-resistance of the whole-plant studies. The resistant S. vulgaris plants produced fewer seeds. Differences in cross-resistance patterns to PS II-inhibiting herbicides and the difference in fitness cost could be exploited in a weed management program.

DNA Mutational Analysis↗
PubMed2000

Biosynthesis of spermidine, a direct precursor of pyrrolizidine alkaloids in root cultures of Senecio vulgaris L.

The polyamine spermidine is an essential biosynthetic precursor of pyrrolizidine alkaloids. It provides its aminobutyl group which is transferred to putrescine yielding homospermidine, the specific building block of the necine base moiety of pyrrolizidine alkaloids. The enzymatic formation of spermidine was studied in relation to the unique role of this polyamine as an alkaloid precursor. S-adenosylmethionine decarboxylase (SAMDC, EC 4.1.1.50) and spermidine synthase (SPDS, EC 2.5.1.16) from root cultures of Senecio vulgaris were partially purified and characterized. The SAMDC-catalyzed reaction showed a pH optimum of 7.5, that of SPDS an optimum of 7.7. The Km value of SAMDC for its substrate S-adenosylmethionine (SAM) was 15 microM, while the apparent Km values of SPDS for its substrates decarboxylated SAM (dSAM) and putrescine were 4 microM and 21 microM, respectively. The relative molecular masses of the two enzymes, determined by gel filtration, were 29000 (SAMDC) and 37000 (SPDS). Studies with various potential inhibitors revealed, for most inhibitors, profiles that were similar to those established with the respective enzymes from other plant sources. However, putrescine which is not known to be an inhibitor of plant SAMDC, strongly inhibited the enzyme from S. vulgaris roots. Spermidine synthase was sensitive to inhibition by its product spermidine. In the presence of the stationary tissue concentrations of the two polyamines (ca. 0.1 mM each) the activities of SAMDC and SPDS would be inhibited by >80%. The results are discussed in relation to the role of spermidine in primary and secondary metabolism of alkaloid-producing S. vulgaris root cultures.

Adenosylmethionine Decarboxylase↗
PubMed2005

Quantitative assessment of heteroplasmy levels in Senecio vulgaris chloroplast DNA.

Heteroplasmy in coding chloroplast DNA was only recently shown to occur and was so far not quantitatively assessed. We present a quantitative analysis of cpDNA heteroplasmy levels at a triazine-resistance determining site within and between individual Senecio vulgaris plants. Detectable levels of heteroplasmic haplotypes were observed in all tested plants. As expected, the levels of heteroplasmy vary greatly between plants. However, even within individual plants, the fraction of one haplotype may cover a range from below 1% to well over 90%. Our results suggest that heteroplasmy may be a common phenomenon in S. vulgaris. Possible consequences for molecular diagnostics of chloroplast encoded traits as well as evolutionary consequences of chloroplast heteroplasmy are discussed.

DNA, Chloroplast↗
PubMed2005

Isolation and characterization of a polymorphic stigma-specific class III peroxidase gene from Senecio squalidus L. (Asteraceae).

A novel stigma-specific class III peroxidase gene, SSP (Stigma-Specific Peroxidase), has been isolated from the self-incompatible daisy Senecio squalidus L. (Asteraceae). Expression of SSP in flower buds is developmentally regulated, with maximal levels of expression coinciding with anthesis, when stigmas are most receptive to pollen and when self-incompatibility is fully developed. In situ hybridization revealed SSP expression to be localized exclusively to the specialized secretory epidermal cells (papillae) of the stigma, which receive and discriminate pollen. SSP is therefore the first tissue-specific and cell-specific peroxidase gene identified in a plant. SSP belongs to a distinct clade of class III plant peroxidases that possess two introns, instead of the more normal situation of three conserved introns. The deduced amino acid sequence of SSP revealed a 27 amino acid signal peptide, suggesting that the SSP protein is secreted to the cell wall of the stigmatic papillae. In-gel peroxidase activity assays showed that SSP has relatively low peroxidase activity compared to other, as yet uncharacterized, peroxidases present in stigmatic extracts. Six SSP alleles have been cloned from different lines of S. squalidus carrying a range of self-incompatibility (S)-alleles but there was no consistent association between the presence of a particular SSP allele and S-genotype indicating that SSP is not the female determinant of SSI in S. squalidus. Nevertheless, the precise expression of SSP in stigmatic papillae suggests that it may have a more general function in pollen-stigma interactions, or alternatively in protection of stigmas from pathogen attack. Extensive database screens have identified homologues of SSP in other plant species, but available expression data for these genes indicates that none are flower-specific, suggesting that SSP represents a new functional type of class III peroxidase specific to the stigma. We discuss the possible function(s) of S. squalidus SSP in pollen-stigma interactions and in protection of stigmas from pathogen attack.

Alleles↗
PubMed1983

Transfer of [3H]pyrrolizidine alkaloids from Senecio vulgaris L. and metabolites into rat milk and tissues.

[3H]Retronecine and [3H]necic acid-labelled senecionine and seneciphylline were prepared biosynthetically with seedlings of Senecio vulgaris L. using [2,3-3H]putrescine and [4,5-3H]isoleucine, respectively, as precursors. Lactating rats dosed with these differently labelled pyrrolizidine alkaloids (PAs) excreted within 3 h approx. 0.08% of the applied radioactivity in the milk mainly as yet not identified water-soluble retronecine-derived metabolites and with approx. 0.02% as unchanged PAs. Highest tissue levels of PAs and metabolites, 6 h after administration, were found in liver and lungs.

Animals↗
PubMed1989

Effects of dietary pyrrolizidine (Senecio) alkaloids on vitamin A metabolism in rats.

In two experiments, the effect of feeding the pyrrolizidine alkaloid (PA)-containing plant tansy ragwort (Senecio jacobaea) on the metabolism of vitamin A in rats was examined. In Experiment 1, dietary levels of 0, 5 and 10% tansy ragwort and 0, 25,000 and 100,000 IU supplementary vitamin A/kg diet were used. In rats fed tansy ragwort, both plasma and liver concentrations of vitamin A were depressed (P less than 0.05). Plasma values were decreased to about 50% of control values. In Experiment 2, rats fed 5% tansy ragwort had depressed plasma and liver vitamin A concentrations 48 h after oral dosing with vitamin A. Fecal excretion of vitamin A was decreased in tansy ragwort-fed rats. In control rats, most fecal vitamin A was excreted in the first 24 h post-dosing, while in tansy ragwort-fed animals, the excretion was delayed, suggesting a possible effect of PA on gut motility. The results indicate that PA causes reductions in liver and plasma vitamin A concentrations. Postulated mechanisms include an effect of PA on hepatic retinol-binding protein synthesis, and impaired biliary excretion depressing vitamin A absorption.

Animals↗
PubMed1992

Dietary pyrrolizidine (Senecio) alkaloids and tissue distribution of copper and vitamin A in broiler chickens.

The effect of feeding a diet containing 5% tansy ragwort (TR) (Senecio jacobaea), a poisonous plant containing pyrrolizidine alkaloids (PA), on the blood and liver levels of copper, zinc, iron and vitamin A in broiler chicks was examined. Serum and liver copper and liver iron concentrations were increased in chicks fed a diet with 5% TR, while serum and liver zinc and vitamin A decreased. When PA were removed from the diet, partial restoration of normal serum vitamin A level occurred, indicating that the ability to mobilize liver vitamin A is not irreversibly inhibited by PA. The decline in serum vitamin A occurred by 8 days of TR feeding with a concurrent decline in growth rate. When chicks were fed a diet high in vitamin A (25,000 IU/kg), followed by a basal diet containing TR, serum vitamin A levels were significantly (P < 0.01) decreased, while liver vitamin A level increased. This indicates that mobilization of previously stored vitamin A from the liver is impaired by PA. Prior feeding of a high vitamin A level resulted in protective effects against PA toxicity, as assessed by histopathology. This study shows that a dietary source of PA modifies metabolism and tissue distribution of minerals and vitamin A.

Administration, Oral↗
PubMed2006

Transcriptome shock after interspecific hybridization in senecio is ameliorated by genome duplication.

Allopolyploidy, which involves genome doubling of an interspecific hybrid is an important mechanism of abrupt speciation in flowering plants [1-6]. Recent studies show that allopolyploid formation is accompanied by extensive changes to patterns of parental gene expression ("transcriptome shock") [7-15] and that this is likely the consequence of interspecific hybridization rather than polyploidization [16]. To investigate the relative impacts of hybridization and polyploidization on transcription, we compared floral gene expression in allohexaploid Senecio cambrensis with that in its parent species, S. vulgaris (tetraploid) and S. squalidus (diploid), and their triploid F1 hybrid, S. x baxteri [17]. Major changes to parental gene expression were associated principally with S. x baxteri, suggesting that the polyploidization event responsible for the formation of S. cambrensis had a widespread calming effect on altered gene expression arising from hybridization [17]. To test this hypothesis, we analyzed floral gene expression in resynthesized lines of S. cambrensis and show that, for many genes, the "transcriptome shock" observed in S. x baxteri is calmed ("ameliorated") after genome doubling in the first generation of synthetic S. cambrensis and this altered expression pattern is maintained in subsequent generations. These findings indicate that hybridization and polyploidization have immediate yet distinct effects on large-scale patterns of gene expression.

Gene Duplication↗
PubMed2003

Pyrrolizidine alkaloids in and on the leaf surface of Senecio jacobaea L.

This is the first study showing that alkaloids are present on the leaf surface of plants. A concentration of 30-230 pmol/cm2 pyrrolizidine alkaloids (PA's) was detected in 8 different samples taken from Senecio jacobaea. PA concentration on the leaves was marginally correlated with PA concentration of the total leaf tissues. The PA spectrum on the leaf differed from the PA spectrum of the total leaf.

Chemistry Techniques, Analytical↗
PubMed2004

Variation in pyrrolizidine alkaloid patterns of Senecio jacobaea.

We studied the variation in pyrrolizidine alkaloid (PA) patterns of lab-grown vegetative plants of 11 European Senecio jacobaea populations. Plants were classified as jacobine, erucifoline, mixed or senecionine chemotypes based on presence and absence of the PAs jacobine or erucifoline. Due to the presence of jacobine, total PA concentration in jacobine chemotypes was higher than in erucifoline chemotypes. Both relative and absolute concentrations of individual PAs differed between half-sib and clonal families, which showed that variation in PA patterns had a genetic basis. Within most populations relative abundance of PAs varied considerably between individual plants. Most populations consisted either of the jacobine chemotype or of the erucifoline chemotype, sometimes in combination with mixed or senecionine chemotypes.

Genetic Variation↗
PubMed2006

Secondary metabolites from Senecio burtonii (Compositae).

A cacalolide derivative named 4alpha-[2'-hydroxymethylacryloxy]-1beta-hydroxy-14-(5-->6) abeo eremophilan-12,8-olide and a shikimic acid derivative named (3'E)-(1alpha)-3-hydroxymethyl-4beta,5alpha-dimethoxycyclohex-2-enyloctadec-3'-enoate along with three known compounds, octacosan-1-ol, 3beta-hydroxyolean-12-en-28-oic acid and 3beta-acetoxyolean-12-en-28-oic acid were isolated from Senecio burtonii. Their structures and relative configurations were established on the basis of spectroscopic analysis.

Molecular Structure↗
PubMed2002

Alkaloids from Senecio aquaticus.

Erucifoline (1) and 9-angeloylhastanecine (2) were isolated from the aerial parts of Senecio aquaticus. Five other pyrrolizidine alkaloids were tentatively identified by GC/MS analysis: jacobine; seneciphylline; spartioidine; jacozine; and senecionine.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

The effect of Senecio latifolius a plant used as a South African traditional medicine, on a human hepatoma cell line.

A number of traditional remedies used in South Africa contain pyrrolizidine alkaloids, some of which are hepatotoxic. We investigated the effect on human HuH-7 cells of Senecio latifolius DC., a plant that is a component of some traditional remedies and which is known to contain toxic pyrrolizidine alkaloids. Cells were also treated with extracts of a standard pyrrolizidine, retrorsine. The changes in the gross morphology of the cells were studied using light microscopy after haematoxylin and eosin staining. The cytoskeleton was investigated using fluorescence-labelled anti-beta-tubulin antibody and the nuclear organisation was studied using fluorescence-labelled antinuclear antibodies. The plant extracts gave rise to dose-dependent gross morphological changes. At high doses, we observed necrosis and at lower doses, destruction of the cytoskeleton, nuclear fragmentation and apoptosis. Doses of less than the equivalent of 330 ng/ml retrorsine led to multinucleated cells with failure in spindle formation and clumping of nuclear chromatin. This latter finding suggests that chronic low-dose treatment with such traditional remedies could give rise to teratogenic and/or carcinogenic effects.

Antineoplastic Agents, Phytogenic↗
PubMed2002

Induction of micronuclei by alkaloids extracted from Senecio brasiliensis and stored for 23 years.

In the present study, we report the results of an investigation on pyrrolizidine alkaloids extracted from Senecio brasiliensis (Sprengel) Less., which were stored for more than 23 years under variable conditions of temperature and humidity and exposed to light. Both the crude alkaloid (integerrimine+retrorsine+impurities) and pure integerrimine conserved the ability to induce acute toxicity in mice, leading to the death of the animals in less than 24h. The alkaloids also conserved the potential to induce significant increases in micronucleus frequencies in polychromatic erythrocytes of mouse bone marrow compared to the negative control. The administration of alkaloids to lymphocyte cultures blocked with cytochalasin-B showed no significant increase in micronucleus frequency in binucleated cells, probably due to the lack of a metabolic activation mechanism. However, an antimitotic effect was observed.

Adult↗
PubMed2001

Defensive chemistry of Senecio miser.

Three eremophilanolides, 1alpha-acetoxy-8beta-methoxy-10betaH-eremophil-7(11)-en-8alpha,12-olide (1); 1alpha-angeloyloxy-6beta-hydroxy-8beta-methoxy-10betaH-eremophil-7(11)-en-8alpha,12-olide (2); and 1alpha-angeloyloxy-8betaH,10betaH-eremophil-7(11)-en-8alpha,12-olide (3), and two pyrrolizidine alkaloids, integerrimine (4) and its N-oxide (5), were isolated from bioactive fractions of Senecio miser. The structures of the new compounds 1 and 2 were established by NMR spectroscopic analysis and chemical transformation. The X-ray analysis of compound 1 was also performed. Eremophilanolides 1 and 2 and alkaloids 4 and 5 were found to be strong insect antifeedants, further supporting a proposed defensive role for these classes of compounds.

Animals↗
PubMed2005

Eremophilane-type sesquiterpene derivatives from Senecio aegyptius var. discoideus.

Investigation of a CH(2)Cl(2) extract of the aerial parts of Senecio aegyptius var. discoideus afforded nine eremophilane compounds, of which six are new (1-6), namely, 1beta-hydroxy-8alphaH-eremophil-7(11),9-dien-8beta,12-olide (1), 1beta,8alpha-dihydroxyeremophil-7(11),9-dien-8beta,12-olide (2), 1beta-hydroxy-8alpha-methoxyeremophil-7(11),9-dien-8beta,12-olide (3), 1-oxo-8alpha-methoxy-10alphaH-eremophil-7(11)-en-8beta,12-lactam (4), 1beta,10beta-epoxy-8alpha-hydroxyeremophil-7(11)-en-8beta,12-olide (5), and 1beta,10beta-epoxy-8alpha-methoxyeremophil-7(11)-en-8beta,12-olide (6). The structures of 1-6 were elucidated by spectroscopic methods and by comparison with literature data. The antibacterial activity of the isolated compounds was tested against Bacillus cereus and a Serratia sp.

Anti-Bacterial Agents↗
PubMed2004

Constituents of Senecio chionophilus with potential antitubercular activity.

Two new sesquiterpenoids, (1S,4S,5R,10R)-1-hydroxy-6-isobutyryloxy-10H-9-oxofuranoeremophilane (1) and 1alpha-hydroxy-6beta-(2xi-methylbutyryloxy)-10alphaH-9-oxofuranoeremophilane (2), along with 21 known constituents, were isolated from the n-hexane and dichloromethane extracts of the above-ground biomass and roots of Senecio chionophilus. The structures of 1 and 2 were elucidated on the basis of spectroscopic evidence and chemical transformation methods. The absolute configuration of 1 was determined by Mosher ester methodology. All of the isolates were evaluated for their antitubercular potential against Mycobacterium tuberculosis in a microplate Alamar Blue assay. Compound 2, 6beta-angeloyloxy-1alpha-hydroxy-10alphaH-9-oxofuranoeremophilane (3), and 4'-hydroxyacetophenone (6) exhibited mild antitubercular activity at minimum inhibitory concentrations of 119, 114, and 121 microg/mL, respectively.

Antitubercular Agents↗
PubMed2006

Eremophilanes from Senecio mairetianus and some reaction products.

Eight new eremophilanolides (1, 2, 4-7, 9, and 10), a new eremophilane (13), and several known compounds were isolated from the roots and aerial parts of Senecio mairetianus. The chemical structures were proposed taking into consideration spectroscopic analyses and chemical transformations. X-ray diffraction analysis of 2, 4, and 9 confirmed their structures. The stereochemistry of 1,10-epoxy-8alpha-methoxyermophilanolide (3) was determined. Compounds 4-7, 9, and 10 are possible artifacts obtained by preparation of the alkaloidal extract.

Crystallography, X-Ray↗