Chemical structure of the O-polysaccharide isolated from Pectobacterium atrosepticum SCRI 1039

The lipopolysaccharide (LPS) of the bacterium Pectobacterium atrosepticum SCRI 1039 was hydrolyzed and the products were separated. A study of the obtained O-polysaccharide by means of chemical methods, GLC, GLC–MS, and NMR spectroscopy allowed us to identify a branched polymer with a pentasaccharide repeating unit of the structure shown below, in which the fucose residue was partially O-acetylated at C-2, C-3 or C-4.     

Mist trickling bioreactor for <Emphasis Type="Italic">Centaurium erythraea</Emphasis> Rafn growth of shoots and production of secoiridoids

Shoots of Centaurium erythraea Rafn were cultivated in 5 l mist trickling bioreactor for 21 and 28 days increasing their dry weight from 0.54 g to 13.7 g and 18.3 g, respectively. About 6880 shoots from 223 initial shoot-tips in 21-day bioreactor producing cycle were produced. The shoots could be successfully rooted and transferred to soil. Secoiridoid accumulation (expressed as a sum of gentiopicroside, sweroside and swertiamarin) in shoots after 21 days of culture reached about 303 mg l⁻¹.     

Production of bioactive phenolic acids and furanocoumarins in in vitro cultures of Ruta graveolens L. and Ruta graveolens ssp. divaricata (Tenore) Gams. under different light conditions

Extracts from the biomass of Ruta graveolens and Ruta graveolens ssp. divaricata cultured in vitro under different light conditions (far-red, red and blue light, UV-A irradiation, in darkness and white light) were tested for the amounts of free phenolic acids and cinnamic acid (twelve compounds) as well as furanocoumarins and umbelliferone (seven compounds) using HPLC methods. Total amounts of the investigated groups of compounds in the cultures of both plants increased from 2.6 to 6.7 times, depending on light quality, and the maximum values reached were 106.50 and 1,276.74?mg?100?g^?1 DW (in R. graveolens), and 106.97 and 262.54?mg?100?g^?1 DW (in the subspecies), respectively. Both white light and blue light were equally beneficial for the total production of phenolic acids in cultures of both plants, whereas the total production of furanocoumarins was clearly better stimulated by blue light in R. graveolens and by darkness in the subspecies (i.e. the amounts were respectively 1.44 and 1.7 times higher than in the biomass cultivated under white light). The amounts of individual compounds in both plant cultures increased from about 2.2 to 26.3 times depending on light quality. The following bioactive compounds were obtained in quantities which are of interest from a practical perspective: in R. graveolens culture??protocatechuic acid (45?mg?100?g^?1 DW), isopimpinellin (about 500?mg?100?g^?1 DW) and bergapten (about 270?mg?100?g^?1 DW), and in the subspecies culture: p-coumaric acid (70?mg?100?g^?1 DW) and isopimpinellin (about 210?mg?100?g^?1 DW).     

Assessment of RAPD markers for barley doubled haploid lines resistant and susceptible to Fusarium culmorum at seedling and adult plant growth stages

Thirty doubled haploid (DH) lines of barley derived from F(1) of a cross between the six-rowed cultivar Pomo and two-rowed cultivar Maresi were examined for susceptibility to Fusarium seedling blight (SB) and head blight (FHB), measured by mycotoxin (nivalenol) content of kernels. RAPD (random amplified polymorphic DNA) polymorphism was analysed by using 53 decamer primers. Amplification products (APs) were 200 bp up to 2000 bp in size on average 5.7 per primer and the total number of APs was 284, 51.06% of which were polymorphic. Only 32 APs differentiated the examined DH lines - 19 APs for nivalenol content of kernels and 13 for seedling resistance. DH lines segregated with continuous distribution of resistance to FHB and SB. At the seedling stage all DH lines exhibited lower susceptibility than parental cultivars, but in the adult stage only two lines (MP 2 and MP 7) appeared to be more resistant to FHB, i.e. accumulated in kernels a lower amount of mycotoxin than cultivars Maresi and Pomo.     

Prenatal Exposure to Cadmium,Placental Permeability and Birth Outcomes in Coastal Populations of South Africa

Background

The impact of prenatal exposure to cadmium (Cd) on birth outcomes is an area of concern. This study aimed to assess an impact of prenatal Cd exposure on birth outcomes in distinct coastal populations of South Africa.

Methods

Cadmium was measured in maternal blood (CdB) (n = 641), cord blood and in maternal urine (n = 317). This investigation assessed the associations between CdB (non-transformed) and birth outcomes across the 25^th, 50th, and 75th percentile for birth weight, birth length and head circumference, to test for a linear trend. Associations between natural log-transformed maternal CdB, size at birth and other factors were further evaluated using linear mixed-effects modelling with random intercepts.

Results

The average gestational age in the total sample was 38 weeks; 47% of neonates were female, average birth weight was 3065 g and 11% were of low birth weight (< 2500 g). The geometric mean (GM) of the maternal CdB level was 0.25 μg/L (n = 641; 95% CI, 0.23–0.27). The cord blood Cd level was 0.27 μg/L (n = 317; 95% CI, 0.26–0.29) and urine (creatinine-corrected) Cd level was 0.27 μg/L (n = 318; 95% CI, 0.24–0.29). The CdB cord:maternal ratio in the sub-cohort was 1, suggesting that the placenta offers no protective mechanism to the foetus. An inverse association was found between CdB and the lower birth weight percentile in female neonates only (β = - 0.13, p = 0.047). Mothers who reported eating vine vegetables daily had lower levels of CdB (β = - 0.55, p = 0.025). Maternal smoking was associated with an elevation in natural log-transformed CdB levels in both male and female cohorts.

Discussion

Significant inverse associations between prenatal Cd exposure and birth anthropometry were found in female neonates but not in male neonates, suggesting potential sex differences in the toxico-kinetics and toxico-dynamics of Cd.     

Crystal structure of the core domain of RhoE/Rnd3: a constitutively activated small G protein

We report the 2.1 A crystal structure of the core G protein domain of the unusual Rho family member RhoE/Rnd3 in complex with endogenous GTP and magnesium. Unlike other small G proteins, RhoE, along with two other proteins Rnd1/Rho6 and Rnd2/RhoN, does not hydrolyze GTP. The main reason for this is the presence of serines in the positions equivalent to Ala59 and Gln61 in Ras. The structure shows that there are still water molecules in similar positions to the waters thought to be involved in the hydrolysis reaction in other G proteins. The structure suggests three not necessarily exclusive explanations for the lack of hydrolysis. The lack of the conserved glutamine raises the energy of the transition state inhibiting hydrolysis. The serines may restrain the waters from moving closer to the GTP, a step that is required to attain the transition state. They also stabilize the GTP-bound conformation of switch II and could prevent conformational changes required during hydrolysis. By superposition of the RhoE structure on structures of Rho family proteins in complex with binding partners, we make predictions on RhoE interactions with these partners.     

Ion antagonism in phytochrome-mediated calcium-dependent germination of turions of Spirodela polyrhiza (L.) Schleiden

The light-dependent germination response of turions (resting fronds) is mediated by phytochrome and requires the presence of Ca²⁺ in the medium (K.-J. Appenroth and H. Augsten, 1990, Photochem. Photobiol. 52: 61–65). The Ca²⁺ requirement of germination is apparent only in the presence of exogenous Mg²⁺. A competitive ion antagonism was demonstrated between Ca²⁺ and Mg²⁺ in this physiological response; Mg²⁺ could also be replaced by Ba²⁺ or Sr²⁺. Without exog-enous Mg²⁺, a Ca²⁺ concentration as low as 0.9 μM fulfilled the Ca²⁺ requirement. This type of ion antagonism resembled the competitive Ca/Mg interaction reported previously for calcium-binding proteins. The physiological response was blocked by inhibitors of Ca²⁺ uptake (verapamil, La³⁺). It was concluded that uptake of Ca²⁺ from the external medium is an essential step in the phytochrome-mediated germination of turions. The results are in agreement with the assumption that the uptake of Ca²⁺ is blocked at the side of entry by other alkaline earth ions. Treatment of turions with Mg²⁺ (1 mM) for 24 h at varying times after the red light pulse in otherwise virtually Ca²⁺-free KNO₃ solution resulted in a response similar to a Ca²⁺ step-down treatment. This is in agreement with the assumption that the Ca²⁺- and the Mg²⁺-sensitive periods coincide. The ion interaction described here represents the first photophysiological example in plants of an antagonistic effect between Ca²⁺ and Mg²⁺ similar to that which occurs in vitro with calmodulin. Received: 12 June 1998 / Accepted: 28 December 1998     

Presence of 3-Hydroxyanthranilic Acid in Rat Tissues and Evidence for Its Production from Anthranilic Acid in the Brain

As assessed by HPLC with electrochemical detection, 3-hydroxyanthranilic acid (3-HANA) was found to be present in the rat brain and peripheral organs. The highest concentrations were measured in the kidney (86 fmol/mg of tissue) and spleen (56 fmol/mg of tissue), whereas the adrenal gland, liver, heart, and several forebrain areas (hippocampus, striatum, parietal cortex, thalamus, amygdala/pyriform cortex, and frontal cortex) contained less 3-HANA (between 15 and 22 fmol/mg of tissue). Slightly lower concentrations of 3-HANA were found in the brainstem and the cerebellum. The metabolic disposition of 3-HANA was examined in tissue slices which were incubated in Krebs-Ringer buffer at 37 degrees C in vitro. Incubation for up to 2 h did not affect 3-HANA concentration in brain tissue. However, inhibition of 3-HANA degradation by the specific 3-hydroxyanthranilic acid oxygenase blocker 4-chloro-3-hydroxyanthranilic acid (4-Cl-3-HANA; 10 microM) resulted in a rapid (within 2.5 min) doubling of 3-HANA levels in slices from cerebral cortex. No further increases were observed after incubations of up to 120 min. Exposure of cortical slices to 3-HANA's putative bioprecursors, 3-hydroxykynurenine (3-HK) and anthranilic acid (ANA), in the absence of 4-Cl-3-HANA resulted in rapid, transient increases in 3-HANA production. Maximal 3-HANA synthesis from ANA exceeded the maximal effect of 3-HK by approximately 11-fold.2+ In the presence of 4-Cl-3-HANA, 1 mM ANA produced 9.0 +/- 0.3 and 89.0 +/- 9.3 (5 min) or 51.6 +/- 7.9 and 187.5 +/- 11.2 (120 min) fmol of newly synthesized 3-HANA/mg of brain tissue, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)