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PubMed1997

Sequence and mutational analysis of the 6.7-kb region containing nodAFEG genes of Rhizobium sp. strain N33: evidence of DNA rearrangements.

A 6.7-kb region upstream of nodBC genes in Rhizobium sp. strain N33 was shown to contain the nodAFEG genes and an open reading frame designated orfZ. The open reading frames for these genes contain 591, 282, 1209, 738, and 1,338 nucleotides respectively. Homologues of these genes were found in other rhizobia with the exception of orfZ, for which there was no counterpart found in the Genbank/EMBL database. Tn5 mutagenesis in nodEG and in the intergenic nodG-B region has shown a Nod+ phenotype on their temperate hosts Onobrychis viciifolia and Astragalus cicer. The nodules formed on O. viciifolia plants by these mutants were altered in shape and size. However, on A. cicer there was only a reduction in the number of nodules formed, compared with the wild-type strain. Sequence analysis of the orfZ-nodA and nodG-B intergenic regions indicates the presence of truncated nodD genes.

DNA Mutational Analysis↗
PubMed1990

Swainsonine induces the production of hybrid glycoproteins and accumulation of oligosaccharides in male reproductive tissues of the rat.

Early studies have shown that spotted locoweed (Astragalus lentiginosus) has an adverse effect on male reproduction. Rams fed locoweed showed a reduced number of primary and secondary spermatocytes and spermatids in the testis, and of spermatozoa in the epididymis and vas deferens. In addition, the Sertoli cells and other epithelial cells were severely vacuolated. Swainsonine, an indolizidine alkaloid, has been identified as the sole or principal toxin in locoweed and perhaps in the plants of genus Swainsona. The toxin is an inhibitor of lysosomal alpha-D-mannosidase, cytosolic alpha-D-mannosidase, and Golgi mannosidase II. The in vitro and in vivo inhibition of Golgi mannosidase II induces the production of abnormal glycoproteins. Since epididymis-mediated modifications of sperm-surface glycoproteins are believed to be important for sperm-egg interactions, we initiated studies to determine effects of swainsonine on processing and catabolism of N-linked glycoproteins in male reproductive tissues. The results presented in this report indicate that feeding of the alkaloid led to accumulation of mannose-rich oligosaccharides (OS) in the testis and epididymis of rats. The major OS was purified from the reproductive tissues of swainsonine-fed rats, and its structure was deduced by comparison of the size of the OS before and after treatment with jack bean alpha-D-mannosidase, and by affinity column chromatography. In addition, the rat epididymal epithelial cells produced abnormal glycoproteins when cultured in the presence of the toxin. This result provides indirect evidence for the presence of a swainsonine-sensitive mannosidase II-like processing enzyme in the epididymal epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed2006

Emended description of the genus Phyllobacterium and description of four novel species associated with plant roots: Phyllobacterium bourgognense sp. nov., Phyllobacterium ifriqiyense sp. nov., Phyllobacterium leguminum sp. nov. and Phyllobacterium brassicacearum sp. nov.

Gram-negative bacteria were isolated from the rhizoplane of Brassica napus in France and from root nodules of Argyrolobium uniflorum, Astragalus algerianus and Lathyrus numidicus growing in the infra-arid zone of southern Tunisia. Based on phylogenetic analysis of the 16S rRNA gene sequences, the seven isolates belong to the Alphaproteobacteria and are related to Phyllobacterium myrsinacearum strains. The isolates formed three clusters; clusters A and C consist of Tunisian strains, whereas cluster B consists of two strains from Brassica napus from France. Phylogenetic reconstruction based on the atpD gene strongly supports their affiliation to the genus Phyllobacterium. DNA-DNA hybridizations revealed that (i) none of the isolates belong to the species P. myrsinacearum, (ii) clusters A and C represent two distinct genomospecies and (iii) the two strains of cluster B represent two separate genomospecies. Distinctive phenotypic features were deduced from numerical analysis of phenotypic data. Based on this polyphasic approach, four novel species are proposed: Phyllobacterium leguminum sp. nov. (type strain ORS 1419T = CFBP 6745T = LMG 22833T), Phyllobacterium ifriqiyense sp. nov. (type strain STM 370T = CFBP 6742T = LMG 22831T), Phyllobacterium brassicacearum sp. nov. (type strain STM 196T = CFBP 5551T = LMG 22836T) and Phyllobacterium bourgognense sp. nov. (type strain STM 201T = CFBP 5553T = LMG 22837T). The description of the genus Phyllobacterium is emended accordingly.

Alphaproteobacteria↗
PubMed2003

Overexpression of selenocysteine methyltransferase in Arabidopsis and Indian mustard increases selenium tolerance and accumulation.

A major goal of phytoremediation is to transform fast-growing plants with genes from plant species that hyperaccumulate toxic trace elements. We overexpressed the gene encoding selenocysteine methyltransferase (SMT) from the selenium (Se) hyperaccumulator Astragalus bisulcatus in Arabidopsis and Indian mustard (Brassica juncea). SMT detoxifies selenocysteine by methylating it to methylselenocysteine, a nonprotein amino acid, thereby diminishing the toxic misincorporation of Se into protein. Our Indian mustard transgenic plants accumulated more Se in the form of methylselenocysteine than the wild type. SMT transgenic seedlings tolerated Se, particularly selenite, significantly better than the wild type, producing 3- to 7-fold greater biomass and 3-fold longer root lengths. Moreover, SMT plants had significantly increased Se accumulation and volatilization. This is the first study, to our knowledge, in which a fast-growing plant was genetically engineered to overexpress a gene from a hyperaccumulator in order to increase phytoremediation potential.

Adaptation, Physiological↗
PubMed2000

The involvement of a cysteine proteinase in the nodule development in Chinese milk vetch infected with Mesorhizobium huakuii subsp. rengei.

Cys proteinases play important roles in plant cell development and senescence. A cDNA, AsNODf32, obtained by differential screening of a nodule cDNA library of the leguminous plant Chinese milk vetch (Astragalus sinicus), represents a nodule-specific Cys proteinase similar to that reported for the actinorhizal Alnus glutinosa-Flankia symbiosis. A characteristic feature of this proteinase is the presence of a putative vacuolar targetting signal, LQDA, within its propeptide. Expression of the AsNODf32 gene, which was studied on northern blots and in situ hybridization, showed good correlation with the onset of nodule senescence. In situ hybridization studies revealed that AsNODf32 was expressed in senescent-infected tissue at the base of the nodule, as well as in interzone II-III of the infected nodules. In addition to degrading old nodule tissues and bacteroids, AsNODf32 protein may be required as a component of tissue remodeling during nodule development.

Amino Acid Sequence↗
PubMed2004

Effects of several Chinese herbal aqueous extracts on human sperm motility in vitro.

The effects of six kinds of aqueous extracts of Chinese herbal medicine (Astragalus membranaceus, Acanthopanacis senticosi, Panax genseng and Ophiopogon japonicus, P. genseng and Aconitum carmichaeli, Salviae miltiorrhiae, Polyporus umbellatus polysaccharide) on sperm motility characteristics of 30 infertile male volunteers were studied in vitro with a computer-assisted sperm analysis at 15, 60 and 180 min after incubated with the drugs. The results showed that per cent viability, number of progressive motile spermatozoa, curvilinear velocity, average path velocity and amplitude of lateral head displacement were significantly enhanced by A. membranaceus (P < 0.05 or < 0.01), per cent viability, average path velocity and amplitude of lateral head displacement were significantly enhanced by A. senticosi (P < 0.05), but all the above were not affected by P. genseng and O. japonicus, P. genseng and A. carmichaeli, S. miltiorrhiae and P. umbellatus polysaccharide. It is suggested that A. membranaceus and A. senticosi can enhance the motility of human spermatozoa in vitro.

Drugs, Chinese Herbal↗
PubMed1977

An outbreak of Swainsona poisoning in horses.

On 6 properties in south-western Queensland an outbreak of nervous disease occurred horses due to ingestion of Swainsonia (Darling pea). Loss of condition, depression, hyperaesthesia and hyperexcitability were seen in affected horses. At autopsy of 2 horses generalised c ytoplasmic vacuolation was seen in the neurones of the central nervous system and in the liver, adrenal and thyroid. The clinical and pathological features were similar to those described in horses suffering from Swainsona poisoning in Australia and Astragalus and Oxytropis in North America.

Animals↗
PubMed2001

Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan.

Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis, are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.

Animals↗
PubMed1984

Identification of swainsonine as a probable contributory mycotoxin in moldy forage mycotoxicoses.

When infested with the fungus Rhizoctonia leguminicola, certain forages, e.g., red clover hay, can cause a "slobber syndrome" of varying severity when consumed by ruminants. The causative agent has been presumed to be slaframine [(1S,6S,8aS)-1-acetoxy-6-aminooctahydroindolizine], which is produced by R. leguminicola. In one serious outbreak of the slobber syndrome in horses, the red clover forage involved was carefully examined and found to contain R. leguminicola and slaframine. An identical hay sample is shown here by ion-exchange chromatographic and gas chromatographic-mass spectrometric analysis of appropriate hay extracts to also contain swainsonine [(1S,2R,8R,8aR)-1,2,8-trihydroxyoctahydroindolizine], a potent alpha-mannosidase inhibitor. Swainsonine has previously been isolated from pure cultures of R. leguminicola and from higher plants, namely the Darling pea (Swainsona canescens) and spotted locoweed (Astragalus lentiginosus). Consumption of Darling pea and spotted locoweed by livestock results in a severe neurological condition resembling that observed in hereditary mannosidosis in cattle and humans. Our findings indicate that swainsonine may be viewed as a mycotoxin when present in moldy forages consumed by livestock. The extent to which slaframine and swainsonine mycotoxicosis pose threats to animal husbandry and, indeed, to humans, if these alkaloids were to enter the human food chain, deserves serious consideration.

Alkaloids↗
PubMed2003

Enhanced accumulation of Cd2+ by a Mesorhizobium sp. transformed with a gene from Arabidopsis thaliana coding for phytochelatin synthase.

We expressed the Arabidopsis thaliana gene for phytochelatin synthase (PCS(At)) in Mesorhizobium huakuii subsp. rengei B3, a microsymbiont of Astragalus sinicus, a legume used as manure. The PCS(At) gene was expressed under the control of the nifH promoter, which regulates the nodule-specific expression of the nifH gene. The expression of the PCS(At) gene was demonstrated in free-living cells under low-oxygen conditions. Phytochelatin synthase (PCS) was expressed and catalyzed the synthesis of phytochelatins [(gamma-Glu-Cys)(n)-Gly; PCs] in strain B3. A range of PCs, with values of n from 2 to 7, was synthesized by cells that expressed the PCS(At) gene, whereas no PCs were found in control cells that harbored the empty plasmid. The presence of CdCl(2) activated PCS and induced the synthesis of substantial amounts of PCs. Cells that contained PCs accumulated 36 nmol of Cd(2+)/mg (dry weight) of cells. The expression of the PCS(At) gene in M. huakuii subsp. rengei B3 increased the ability of cells to bind Cd(2+) approximately 9- to 19-fold. The PCS protein was detected by immunostaining bacteroids of mature nodules of A. sinicus containing the PCS(At) gene. When recombinant M. huakuii subsp. rengei B3 established the symbiotic relationship with A. sinicus, the symbionts increased Cd(2+) accumulation in nodules 1.5-fold.

Alphaproteobacteria↗
PubMed1999

S-methylmethionine metabolism in Escherichia coli.

Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group from S-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed that Escherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is an S-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants in yagD which also possess defects in metE and metH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in a metE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but not S-methylmethionine in the medium reduces the amount of yagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfD and yagD products appear to reside in the acquisition of S-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.

Aerobiosis↗
PubMed2001

Unusual methyl-branched alpha,beta-unsaturated acyl chain substitutions in the Nod Factors of an arctic rhizobium, Mesorhizobium sp. strain N33 (Oxytropis arctobia).

Mesorhizobium sp. strain N33 (Oxytropis arctobia), a rhizobial strain isolated in arctic Canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera Astragalus, Onobrychis, and Oxytropis. Using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of N33 Nod factors, which are major determinants of nodulation. They are pentameric lipochito-oligosaccharides 6-O sulfated at the reducing end and exhibit other original substitutions: 6-O acetylation of the glucosamine residue next to the nonreducing terminal glucosamine and N acylation of the nonreducing terminal glucosamine by methyl-branched acyl chains of the iso series, some of which are alpha,beta unsaturated. These unusual substitutions may contribute to the peculiar host range of N33. Analysis of N33 whole-cell fatty acids indicated that synthesis of the methyl-branched fatty acids depended on the induction of bacteria by plant flavonoids, suggesting a specific role for these fatty acids in the signaling process between the plant and the bacteria. Synthesis of the methyl-branched alpha,beta-unsaturated fatty acids required a functional nodE gene.

Acyltransferases↗
PubMed2004

Selection of rhizobia for prairie legumes used in restoration and reconstruction programs in Minnesota.

The inoculation of indigenous legumes used in revegetation and wetland reconstruction activities in Minnesota presents problems not found in more traditional seedings. Few studies have sought inoculant-quality rhizobia for the legumes involved or examined their interaction in an environment that involves a number of different legumes seeded simultaneously under initially adverse climatic conditions. In this note, we identify effective strains for Astragalus canadensis, Chamaecrista fasciculata, Dalea purpurea, Dalea candida, Desmodium canadense, and Lespedeza capitata. We are currently using these strains to examine the contribution of inoculated legumes to prairie productivity in Minnesota.

Conservation of Natural Resources↗
PubMed2005

Characteristics of the rhizobia associated with Dalea spp. in the Ordway, Kellogg-Weaver Dunes, and Hayden prairies.

Habitat fragmentation affects the biodiversity and function of aboveground organisms in natural ecosystems but has not been studied for effects on belowground species. In this paper, we consider the diversity of the rhizobia associated with the indigenous legume Dalea purpurea in 3 residual prairie areas in Minnesota and Iowa. Using Dalea purpurea as a trap host, 218 rhizobia were recovered from these soils then characterized using BOXA1R PCR. Three major and 13 minor groups were distinguished based on a similarity of greater than 75% in fingerprint patterns. Each major group consisted almost exclusively of rhizobia from a single prairie, with the diversity of Dalea rhizobia recovered from the Hayden Prairie less than that obtained with rhizobia from the other prairies. Based on 16S rRNA gene sequence analysis, isolates from the Hayden, Ordway, and Kellogg-Weaver Dunes prairies were most similar to Rhizobium etli and Rhizobium leguminosarum, Rhizobium gallicum, and Mesorhizobium amorphae and Mesorhizobium huakuii, respectively. This variation in the dominant microsymbiont species across the 3 prairies studied was unexpected but could have been influenced by the limited number of samples that we were allowed to take, by unanticipated cross-nodulation between native legumes, and by variation in the range of legume species present in each residual prairie area. While some of the rhizobia from Dalea nodulated Phaseolus vulgaris, Macroptilium atropurpureum, Leucaena leucocephala, and Onobrychis viciifolia in addition to the Dalea species tested, others nodulated Astragalus canadensis or Amorpha canescens.

DNA, Bacterial↗
PubMed2006

Inhibitory effects of astragaloside IV on diabetic peripheral neuropathy in rats.

Astragaloside IV (AGS-IV), a new glycoside of cycloartane-type triterpene isolated from the root of Astragalus membranaceus (Fisch.) Bunge, has been used experimentally for its potent immune-stimulating, anti-inflammatory, and antioxidative actions. A recent study has shown AGS-IV to be an aldose-reductase inhibitor and a free-radical scavenger. This study examined the effects of AGS-IV on motor nerve conduction velocity (MNCV), tailflick threshold temperature, biochemical indexes, and the histology of the sural nerve after diabetes was induced in rats with 75 mg/kg streptozotocin (STZ). AGS-IV (3, 6, 12 mg/kg, twice a day) was administered by oral gavage for 12 weeks after diabetes was induced. Compared with control (nondiabetic) rats, obvious changes in physiological behaviors and a significant reduction in sciatic MNCV in diabetic rats were observed after 12 weeks of STZ administration. Morphological analysis showed that AGS-IV suppressed a decrease in myelinated fiber area, an increase in myelinated fiber density, and an increase in segmental demyelination in diabetic rats. The protective mechanism of AGS-IV involved a decrease in declining blood glucose concentration and HbA1C levels, and an increase in plasma insulin levels. AGS-IV increased the activity of glutathione peroxidase in nerves, depressed the activation of aldose reductase in erythrocytes, and decreased the accumulation of advanced glycation end products in both nerves and erythrocytes. Moreover, AGS-IV elevated Na+,K+-ATPase activity in both the nerves and erythrocytes of diabetic rats. These results indicate that AGS-IV exerts protective effects against the progression of peripheral neuropathy in STZ-induced diabetes in rats through several interrelated mechanisms.

Adenosine Triphosphatases↗
PubMed2005

Effect of astragalosides on intracellular calcium overload in cultured cardiac myocytes of neonatal rats.

Astragalosides were the main active components from a native Chinese herb Astragalus membranaceus. Recent studies have shown that Astragalosides have a protective effect on myocardial injury in rats. The present study was designed to investigate the effect of Astragalosides on intracellular calcium overload and sarcoplasmic reticulum calcium load (SR Ca2+ load) in cultured cardiac myocytes from neonatal rats. Astragalosides (100 microg/ml) were incubated in the presence of isoproterenol (ISO) (10(-5) M) for 72 hours in cardiomyocytes. Metoprorol (10(-6) M), a beta1-selective antagonist, was cultured in the same condition as Astragalosides. The result showed that intracellular calcium concentration ([Ca2+]i) and SR Ca2+ load increased in ISO-treated cardiac myocytes as compared to control (P < 0.01). Astragalosides prevented ISO-induced increase in [Ca2+]i and SR Ca2+ load. Metoprolol also inhibited those increase. The mRNA expression and activity of sarcoplasmic reticulum Ca2+ ATPase (SERCA) were enhanced following ISO treatment in cardiac myocytes, and these increases were inhibited by Astragalosides or metoprolol (P < 0.05). The decrease of superoxide dismutase (SOD) activity and the elevation of intracellular maleic dialdehyde (MDA) were observed after ISO treatment in cardiac myocytes. Both Astragalosides and metoprolol restored the SOD activity and reduced the level of MDA. We conclude that Astragalosides have the effects on reducing [Ca2+]i and SR Ca2+ load, enhancing free radical removal and decreasing lipid peroxidation in ISO-treated cardiomyocytes, which might account for their protective effect on myocardial injury.

Aldehydes↗
PubMed2005

Effects of medicinal herb tea on the smoking cessation and reducing smoking withdrawal symptoms.

Medicinal herbs (21 species) were screened for the antioxidant activity and nicotine degradation activity (NDA) in vitro. Eleven of them with higher antioxidant activity and NDA were selected for preparation of the medicinal herb tea (MHT) and the effects of MHT on smoking cessation and reducing smoking withdrawal symptoms were evaluated in 100 male human smokers. Among these medicinal herbs, Eugenia aromaticum and Astragalus membranaceus Bunge showed the highest antioxidant activity (IC50 of 30.0 microg/mL) and NDA (1.81), respectively. MHT showed relatively high antioxidant activity (IC50 of 50.6 microg/mL) and NDA (1.23). The urinary cotinine level, a metabolite of nicotine, increased in the first 2 weeks and greatly decreased from the 2nd to 4th week in the MHT taking group, which indicates that MHT accelerates the conversion of nicotine into cotinine. Human groups taking MHT for 4 weeks underwent reduced smoking withdrawal symptoms compared to the non-MHT taking subjects, and 38% of subjects taking MHT succeeded in smoking cessation, while only 12% of non-MHT taking subjects succeeded in quitting smoking.

Adult↗
PubMed2003

Antiinflammatory activity of astragaloside IV is mediated by inhibition of NF-kappaB activation and adhesion molecule expression.

The regulated expression of adhesion molecules on the surface of endothelial cells is a key process in the pathogenesis of inflammation. The saponin astragaloside IV (AS-IV), a 3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosylcycloastragenol purified from the Chinese medical herb Astragalus membranaceus (Fisch) Bge. has been shown to have anti-inflammatory effects in vivo. In this study we have investigated the effect of AS-IV on cytokine-and LPS-stimulated expression of adhesion molecules in and leukocyte adhesion to endothelial cells. We have demonstrated that AS-IV significantly reduced the adhesion promoting activity of LPS-stimulated HUVECs for polymorph-nuclear leukocytes (PMNs) and the monocytic cell line THP-1. Furthermore, by using specific cell ELISAs we could show that AS-IV decreased the LPS-induced expression of E-selectin and VCAM-1 on the surface of HUVECs in a dose and time dependent manner, whereas the expression of ICAM-1 was not affected by AS-IV. AS-IV also inhibits TNFalpha-induced VCAM-1 expression. The saponin octyl-D-glucopyranoside had no effect on the LPS-induced expression of E-selectin and VCAM-1 excluding an unspecific detergent-like effect of AS-IV. Moreover, AS-IV significantly inhibited LPS- and TNFalpha-induced specific mRNA levels for E-selectin and VCAM-1. Finally, we could show that AS-IV completely abolished LPS- and TNFalpha-induced nuclear translocation of NF-kappaB and NF-kappaB DNA binding activity in endothelial cells. We conclude that the ability of AS-IV to inhibit the NF-kappaB pathway might be one under-lying mechanism contributing to its anti-inflammatory potential in vivo.

Anti-Inflammatory Agents↗