Precipitation of Metallic Cations by the Acidic Exopolysaccharides from Bradyrhizobium japonicum and Bradyrhizobium (Chamaecytisus) Strain BGA-1

The interaction between the acidic exopolysaccharides produced by two Bradyrhizobium strains and several metal cations has been studied. Aqueous solutions in the millimolar range of Fe³⁺ but not of Fe²⁺ precipitated the exopolysaccharides from Bradyrhizobium (Chamaecytisus) strain BGA-1 and, to a lesser extent, Bradyrhizobium japonicum USDA 110. The precipitation was pH dependent, with a maximum around pH 3. The precipitate was redissolved by changing the pH and by Fe³⁺ reduction or chelation. Deacetylation of B. japonicum polysaccharide increased its precipitation by Fe³⁺. At pH near neutrality, the polysaccharide from Bradyrhizobium (Chamaecytisus) strain BGA-1 stabilized Fe³⁺ solutions, despite the insolubility of Fe(OH)₃. Aluminum precipitated Bradyrhizobium (Chamaecytisus) polysaccharide but not the polysaccharide produced by B. japonicum. The precipitation showed a maximum at about pH 4.8, and the precipitate was redissolved after Al³⁺ chelation with EDTA. Precipitation was inhibited by increases in the ionic strength over 10 mM. Bradyrhizobium (Chamaecytisus) polysaccharide was also precipitated by Th⁴⁺, Sn²⁺, Mn²⁺, and Co²⁺. The presence of Fe³⁺ increased the exopolysaccharide precipitation by aluminum. No precipitation, gelation, or increase in turbidity of polysaccharide solutions occurred when K⁺, Na⁺, Ca²⁺, Mg²⁺, Cu²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Hg²⁺, or U⁶⁺ was added at several pH values. The results suggest that the precipitation is based on the interaction between carboxylate groups from different polysaccharide chains and the partially hydrolyzed aquoions of Fe³⁺, Al³⁺, Th⁴⁺, and Sn²⁺.     

The use of Tagasaste (Chamaecytisus proliferus) from different origins for biomass and paper production

In order to identify faster-growing non-woody species usable for biomass and paper production, four Tagasastes (Chamaecytisus proliferus) from different origins are tested. All the Tagasaste species (T. Huelva, T. Australia, T. New Zealand and T. La Palma island) show a good soil and climatic adaptation to Southwest Spain. The studied Tagasaste provenances shows biomass productivity ranges from 1.0 t ha(-1)yr(-1) to 3.4 th a(-1)yr(-1) (o.d.b.) and 25.3 t ha(-1)yr(-1) to 49.4 t ha(-1)yr(-1) under Mediterranean conditions for first and second year sprouts, respectively. The quantity of solubles and extractives shows similar values when compared with wood materials. A relatively lower lignin content in Tagasaste (from 13.7% to 17.1%) species has been found with respect to other vegetal species. The alpha-celullose contents (43.6-45.3%) were in the range of the normal values expected for the other non-wood raw materials. The study confirms the feasibility of the organocell yield pulping process to Tagasaste provenances. Organocell processes provide an efficient delignification (kappa index from 7.2 to 10.9 and pulp yield from 43.6% to 54.1%). The best results are obtained for the physical properties of paper sheets for Tagasaste from Australia in the second year, with values of tensile index of 16.0 kNm/kg, burst index of 1.12 MPa m2/kg and tear index of 0.55 Nm2/kg.     

Morphological variation in the Chamaecytisus proliferus (L.f.) Link complex (Fabaceae: Genisteae) in the Canary Islands

FRANCISCO-ORTEGA, J., JACKSON, M. T., SANTOS-GUERRA, A. & FORD-LLOYD, B. V., 1993. Morphological variation in the Chamaecytisus proliferus (L.f.) Link complex (Fabaceae: Genisteae) in the Canary Islands . A multivariate study (Principal Component Analysis and Cluster Analysis, Warďs method) of 47 morphological traits from 164 populations of Chamaecytisus proliferus (L.f.) Link from the Canary Islands confirmed that this species complex is formed by seven morphological types. At least eight traits discriminated between these types. Patterns of variation follow a cline within Gran Canaria, Tenerife and La Palma. These results also show that morphological variation is greater in the eastern islands (i.e. Gran Canaria and Tenerife) than in the western islands (La Gomera, El Hierro and La Palma) and that no morphological differences are found between plants of typical tagasaste from wild and cultivated populations.     

Numerical analyses of RAPD data highlight the origin of cultivated tagasaste (Chamaecytisus proliferus ssp. palmensis) in the Canary Islands

Random Amplified Polymorphic DNA (RAPD) was used to generate molecular markers to trace the origin of the fodder legume tagasaste (Chamaecytisus proliferus (L. fil.) Link ssp. palmensis (H. Christ) Kunkel) in the Canary Islands. Results from multivariate analyses of data through Two Way Indicator Species Analysis (TWINSPAN) and Detrended Correspondence Analysis (DECORANA) showed that genotypes collected on the island of La Palma exhibited a wider range of variation than those from the other islands. This supports the existing hypothesis that tagasaste originated on La Palma and emphasizes the importance of conserving and evaluating germ plasm from this island.     

On the nomenclature and types of Chamaecytisus proliferus (L.f.) Link (Fabaceae: Genisteae), a fodder shrub from the Canary Islands

The name Cytisus proliferus L.f. is here considered perfectly acceptable and should not be replaced by Cytisus prolifer L.f. One specimen from The Natural History Museum, London is confirmed as the lectotype of Cytisus proliferus L.f. Two specimens from the collection of the Swiss botanist Hermann Christ from the Main Herbarium of the Zurich Botanical Garden were selected as lectotypes for Cytisus proliferus L.f. var. canariae H. Christ and Cytisus proliferus L.f. var. palmensis H. Christ. The name Cytisus proliferus Kit. is typified and a specimen from Paul Kitaibel's collection at the Botanical Department of the Hungarian Natural History Museum is assigned as its lectotype.     

Characterization of vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus proliferus, and of their ethyleneglycol pulps

We characterized vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus proliferus as pulping raw materials and found C. proliferus and cotton stalks to be the best for the intended purpose on the grounds of their increased contents in holocellulose (79.73% and 72.86%) and alpha-cellulose (45.37% and 58.48%), and their decreased contents in ethanol-benzene extractables (2.64% and 1.42%), hot water solubles (2.79% and 3.33%) and 1% soda solubles (16.67% and 20.34%). These properties resulted in increased pulp yields and hence in efficient use of these two types of raw material. The previous raw materials were pulped by using an ethyleneglycol concentration of 65% at 180 degrees C for 75min, followed by beating at 1500 revolutions in a PFI refiner. The paper sheets obtained were characterized and those from C. proliferus found to be the best overall as they exhibited an increased breaking length (4644m), stretch (2.87%), burst index (2.46kN/g) tear index (0.33mNm(2)/g) and brightness (49.92% ISO); in addition C. proliferus pulp was obtained with a high-yield (62.88%). On the other hand, vine shoots provided the poorest results among the studied raw materials.     

Screening for plant growth-promoting rhizobacteria in Chamaecytisus proliferus (tagasaste), a forage tree-shrub legume endemic to the Canary Islands

Rhizobacteria with properties related to plant growth-promotion were isolated from the rhizosphere of the perennial legume Chamaecytisus proliferus ssp. proliferus var. palmensis (tagasaste) growing in field conditions. Samples were collected in two localities of the Tenerife Island: La Laguna and El Tanque, NE and NW at 600 and 1000 meters above sea level, respectively, and in two seasons, winter and summer. The strains were isolated by using culture dependent procedures, and identified by phenotypic (culturable and biochemical) and genotypic (ERIC-PCR fingerprinting) features. The rhizosphere isolates formed a diverse community of mainly Gram-negative bacteria, with members of genera Pseudomonas, Burkholderia and Sphingomonas being predominant. A high level of selectivity was found in the rhizosphere environment as compared to the non-rhizosphere soil where Gram-positives were more abundant. Species richness (number of species) and species abundance were related to the sampling season and the locality, thus, samples obtained in winter at both sites had larger counts than samples obtained in summer, and the higher species richness was found in La Laguna. The species Pseudomonas fluorescens showed the highest number of properties related to plant growth promotion (PGP): 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, phytohormone production, nitrogen fixation, fungal growth inhibition and cyanogenesis, thus it seems to be the most suitable microorganism to be tested in PGP-field experiments.     

Regeneration of Plantlets from Callus Cultures of Chamaecytisus purpureus and Chamaecytisus austriacus (Leguminosae)*

Plant regeneration via organogenesis and embryogenesis was obtained from callus cultures of Chamaecytisus purpureus and Chamaecytisus austriacus. While 2,4-D (4 or 0.5 mg/l) proved highly efficient for callus induction, a combination of 0.1 mg/l IBA and 10 mg/1 BAP induced a high frequency of shoots from the calli. It is shown that, beside the growth factors, the composition of the basal medium represents a critical factor for regeneration. With increasing culture age, a strong reduction of the differentiation capacity was observed.     

Synthesis of a low-molecular-weight form of exopolysaccharide by Bradyrhizobium japonicum USDA 110

A novel extracellular low-molecular-weight polysaccharide was detected as a contaminant within extracellular cyclic beta-1,6-beta-1,3-glucan preparations from Bradyrhizobium japonicum USDA 110 cultures. Compositional analysis, methylation analysis, and nuclear magnetic resonance analysis revealed that this low-molecular-weight polysaccharide was composed of the same pentasaccharide repeating unit previously described for the high-molecular-weight form of the exopolysaccharide (EPS) synthesized by B. japonicum strains. Mass spectrometry analysis indicated that the size of this low-molecular-weight form of EPS was consistent with a dimeric form of the pentasaccharide repeating unit.     

Acidic glycolipids from kidney of suncus (Insectivora)

Lipids were extracted from the kidney of house musk shrew (Suncus murinus), which belongs to the order Insectivora. Acidic glycosphingolipids were purified from lipid extracts by mild alkaline methanolysis followed by column chromatographies on DEAE-Sephadex and silica beads (Iatrobeads). Purified glycolipids were analyzed by thin-layer chromatography, mild acid hydrolysis, gas liquid chromatography of the methyl glycosides after methanolysis and gas chromatography-mass spectrometry of the partially methylated alditol acetates. The kidney of suncus was unique in that it contained ganglioside GM2 (NeuAc type, 28.7 nmol and NeuGc type, 15.8 nmol/g tissue) as the major ganglioside. GM4 (NeuAc) (2.6 nmol/g), and GM3 (NeuAc type, 11.5 nmol and NeuGc type, 8.7 nmol/g) were also present. The content (298.9 nmol/g) of galactosyl sulfatide (GalCer-I3-sulfate) was higher than the values reported previously for other animal species. The total amount of acidic groups in glycolipids of suncus kidney was compared with the values for the kidney of 4 placental mammals to obtain an allometric correlation: log Y = 0.266 + 0.780 log X where X designates body weight, kg and Y, total acidic groups, mumol. A highly significant correlation (r = 0.999) was obtained among values from 5 representative placental mammals which live in mesic environments, suggesting that acidic glycosphingolipids are essential for the kidney function.     

N2-Fixation, nodule efficiency and biomass accumulation after two years in three Chilean legume trees and Tagasaste Chamaecytisus proliferus subsp. palmensis

Initial results of a long-term field experiment are presented for the above and below-ground biomass accumulation after two years, as well as root nodulation, nodule efficiency (g N fixed/g nodules) and biological N₂ fixation (using the ¹⁵N isotope dilution method) of four N₂-fixing tree species (NFTs) grown in the subhumid mediterranean-climate zone of central Chile. Two non-legume tree species, Fraxinus excelsior and Schinus polygamus, were used as reference plants for the isotope dilution calculations.Over two years, Tagasaste (Chamaecytisus proliferus subsp. palmensis, a Papilionoideae from the Canary Islands), produced 10 to 20 times more biomass than the other three NFTS (Acacia caven, Prosopis alba and P. chilensis); all Mimosoideae native to Chile, and nodulation and nitrogen fixed were an order of magnitude higher as well. At the end of the second year, the percentage of N derived from N₂ fixation (%Ndfa) in Tagasate averaged 85.6, equivalent to ca. 49.1 g N fixed per tree. For all four NFTs, however, %Ndfa, nodule efficiency, and total N accumulation varied from one year to the next; caution is thus required in interpreting or predicting NFT performance over the long term, even if Tagasaste can already be considered a highly promising NFT for central Chile.     

O-antigen from Bradyrhizobium japonicum lipopolysaccharide inhibits intercellular (symplast) communication between soybean (Glycine max) cells

The technique of fluorescence redistribution after photobleaching was utilized to measure intercellular movement of low molecular weight fluorescent hydrophilic substances across the cell wall/membrane interface between contiguous soybean (Glycine max (L.) Merr. cv. Mandarin) root cells (SB-1 cell line) in tissue culture. Lipopolysaccharide (LPS) purified from Bradyrhizobium japonicum R110d, a Gram-negative bacterium that normally infects and induces nodulation in soybean roots in vivo, inhibits intercellular communication between the soybean cells in a dose-dependent manner. In contrast, LPS from noninfecting strains failed to yield the same effect. The inhibitory activity of the LPS was localized to the O-antigen region of the LPS.     

Succinate Dehydrogenase (Sdh) from Bradyrhizobium japonicum Is Closely Related to Mitochondrial Sdh

The sdhCDAB operon, encoding succinate dehydrogenase, was cloned from the soybean symbiont Bradyrhizobium japonicum. Sdh from B. japonicum is phylogenetically related to Sdh from mitochondria. This is the first example of a mitochondrion-like Sdh functionally expressed in Escherichia coli.     

Characterization of exopolysaccharide (EPS) produced by Weissella hellenica SKkimchi3 isolated from kimchi

Weissella hellenica SKkimchi3 produces the higher exopolysaccharide (EPS) on sucrose than lactose, glucose, and fructose at pH 5 and 20°C. Sucrose was exclusively used to cultivate SKkimchi3 in all experiments base on the EPS production tests. The molecular mass of EPS, as determined by gel permeation chroma-tography, was 203,000. ¹H and ¹³C NMR analysis indicated that the identity of EPS may be a glucan. When EPS, starch, and cellulose was treated with a-amylase, glucoamylase, glucosidase, and cellulase, glucose was produced from starch and cellulose but was not produced from EPS. Based on HPLC analysis, elemental analysis, ¹H and ¹³C NMR analysis, and enzymatic hydrolysis tests, EPS was estimated to be a glucan. EPS suspension was not precipitated even by centrifugation at 10,000×g for 60 min, and EPS made the fermented milk and bacterial culture viscous.     

Serological grouping of indigenous Bradyrhizobium sp. (Arachis) isolated from various soils of Thailand

ELISA and antibody adsorption tests were applied to determine the minimal somatic antigen constitution of 243 strains of Bradyrhizobium sp. (Arachis) using 12 antisera. The 243 indigenous bradyrhizobial isolates were from 15 sites in four regions of Thailand. A total of 29 serogroups were identified. Most (80%) of the isolates tested had at least one heat-stable antigen in common with strain 280A, forming a so-called 280A serocluster. At 11 of 15 sites tested, 53 to 100% of the isolates fell into one or two predominant serogroups. The serological properties of the indigenous bradyrhizobia were not related to the cropping history of the cultivated fields from which they were isolated.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel; No. 3608-E, 1992 series.     

N-Carboxymethyl-l-serine,a New Acidic Amino Acid from Asparagus (Asparagus officinalis) Shoots

A strongly acidic amino acid—N-carboxymethyl-L-serine—, not previously known in nature, has been isolated from asparagus (Asparagus officinalis) shoots. Some unique properties of this amino acid, such as a much bigger mobility to anode on high voltage paper electrophoresis (pH 3.6) than aspartic acid and characteristic changes of NMR spectra in aqueous solution with various pD, were discussed in relation to its structure.     

Effects of N-starvation and C-source on Bradyrhizobium japonicum exopolysaccharide production and composition, and bacterial infectivity to soybean roots

The exopolysaccharide (EPS) is an extracellular molecule that in Bradyrhizobium japonicum affects bacterial efficiency to nodulate soybean. Culture conditions such as N availability, type of C-source, or culture age can modify the amount and composition of EPS. To better understand the relationship among these conditions for EPS production, we analyzed their influence on EPS in B. japonicum USDA 110 and its derived mutant ΔP22. This mutant has a deletion including the 3′ region of exoP, exoT, and the 5′ region of exoB, and produces a shorter EPS devoid of galactose. The studies were carried out in minimal media with the N-source at starving or sufficient levels, and mannitol or malate as the only C-source. Under N-starvation there was a net EPS accumulation, the levels being similar in the wild type and the mutant with malate as the C-source. By contrast, the amount of EPS diminished in N-sufficient conditions, being poyhydroxybutyrate accumulated with culture age. Hexoses composition was the same in both N-situations, either with mannitol or malate as the only C-source, in contrast to previous observations made with different strains. This result suggests that the change in EPS composition in response to the environment is not general in B. japonicum. The wild type EPS composition was 1 glucose:0.5 galactose:0.5 galacturonic acid:0.17 mannose. In ΔP22 the EPS had no galactose but had galacturonic acid, thus indicating that it was not produced from oxidation of UDP-galactose. Infectivity was lower in ΔP22 than in USDA 110. When the mutant infectivity was compared between N-starved or N-sufficient cultures, the N-starved were not less infective, despite the fact that the amounts of altered EPS produced by this mutant under N-starvation were higher than in N-sufficiency. Since this altered EPS does not bind soybean lectin, the interaction of EPS with this protein was not involved in increasing ΔP22 infectivity under N-starvation.     

Repeats in Transforming Acidic Coiled-Coil (TACC) Genes

Transforming acidic coiled-coil proteins (TACC1, 2, and 3) are essential proteins associated with the assembly of spindle microtubules and maintenance of bipolarity. Dysregulation of TACCs is associated with tumorigenesis, but studies of microsatellite instability in TACC genes have not been extensive. Microsatellite or simple sequence repeat instability is known to cause many types of cancer. The present in silico analysis of SSRs in human TACC gene sequences shows the presence of mono- to hexa-nucleotide repeats, with the highest densities found for mono- and di-nucleotide repeats. Density of repeats is higher in introns than in exons. Some of the repeats are present in regulatory regions and retained introns. Human TACC genes show conservation of many repeat classes. Microsatellites in TACC genes could be valuable markers for monitoring numerical chromosomal aberrations and or cancer.