Growth-inhibitory effects of Galla Rhois-derived tannins on intestinal bacteria

The growth-inhibitory activity of Galla Rhois-derived materials towards 17 intestinal bacteria was evaluated using an impregnated paper disc method. The biologically active components of Galla Rhois were characterized as the tannins methyl gallate (MG) and gallic acid (GA) by spectral analysis. The growth responses varied with bacterial strain tested. In the test using 10 mg disc⁻¹, MG and GA produced a clear inhibitory effect on harmful bacteria such as Clostridium perfringens , Cl. paraputrificum , Eubacterium limosum , Bacteroides fragilis , Staphylococcus aureus and Escherichia coli . Methyl gallate showed no growth-inhibitory activity towards Bifidobacterium adolescentis or B. longum whereas the growth of B. bifidum , B. breve , B. infantis , B. animalis , B. thermophilum , Lactobacillus acidophilus , Lact. plantarum and Streptococcus faecalis was slightly affected. However, GA did not adversely affect the growth of the bifidobacteria and lactobacilli. At 5 mg disc⁻¹, MG significantly inhibited the growth of Cl. perfringens and Cl. paraputrificum but did not affect the growth of the bifidobacteria and lactobacilli. At 1 mg disc⁻¹, MG greatly inhibited the growth of Cl. perfringens alone. These results may be an indication of at least one of the pharmacological actions of Galla Rhois.     

Combined effects of chemical and visual information in eliciting antipredator behaviour in juvenile Atlantic salmon Salmo salar

Under natural conditions, both young-of-the-year (YOY; 0+ year) and parr (1+ year) Atlantic salmon Salmo salar exhibited strong antipredator behaviour ( e.g. increase in latency to resume foraging) following the exposure to damage-released chemical alarm cues relative to a stream water control. Subsequent exposure to a novel visual stimulus had contrasting results. Parr increased their reactive distance to the visual stimulus if they had been previously exposed to a chemical alarm cue, whereas YOY did not. On the other hand, both YOY and parr took significantly longer to resume foraging when exposed to a visual stimulus if they had been previously exposed to a chemical alarm cue than control groups. While YOY and parr differed in the type and intensity of antipredator responses to both chemical and visual stimuli, perhaps due to differential costs and benefits associated with age, both used the chemical and the visual information in a combined manner.     

The 2DX robot: A membrane protein 2D crystallization Swiss Army knife

Among the state-of-the-art techniques that provide experimental information at atomic scale for membrane proteins, electron crystallography, atomic force microscopy and solid state NMR make use of two-dimensional crystals. We present a cyclodextrin-driven method for detergent removal implemented in a fully automated robot. The kinetics of the reconstitution processes is precisely controlled, because the detergent complexation by cyclodextrin is of stoichiometric nature. The method requires smaller volumes and lower protein concentrations than established 2D crystallization methods, making it possible to explore more conditions with the same amount of protein. The method yielded highly ordered 2D crystals diffracting to high resolution from the pore-forming toxin Aeromonas hydrophila aerolysin (2.9 Å), the plant aquaporin SoPIP2;1 (3.1 Å) and the human aquaporin-8 (hAQP8; 3.3 Å). This new method outperforms traditional 2D crystallization approaches in terms of accuracy, flexibility, throughput, and allows the usage of detergents having low critical micelle concentration (CMC), which stabilize the structure of membrane proteins in solution.     

Differing Populations of Endemic Bacteriophages in Cattle Shedding High and Low Numbers of Escherichia coli O157:H7 Bacteria in Feces

The objectives of this study were to identify endemic bacteriophages (phages) in the feedlot environment and determine relationships of these phages to Escherichia coli O157:H7 from cattle shedding high and low numbers of naturally occurring E. coli O157:H7. Angus crossbred steers were purchased from a southern Alberta (Canada) feedlot where cattle excreting ≥10⁴ CFU · g⁻¹ of E. coli O157:H7 in feces at a single time point were identified as supershedders (SS; n = 6), and cattle excreting <10⁴ CFU · g⁻¹ of feces were identified as low shedders (LS; n = 5). Fecal pats or fecal grabs were collected daily from individual cattle for 5 weeks. E. coli O157:H7 in feces was detected by immunomagnetic separation and enumerated by direct plating, and phages were isolated using short- and overnight-enrichment methods. The total prevalence of E. coli O157:H7 isolated from feces was 14.4% and did not differ between LS and SS (P = 0.972). The total prevalence of phages was higher in the LS group (20.9%) than in the SS group (8.3%; P = 0.01). Based on genome size estimated by pulsed-field gel electrophoresis and morphology determined by transmission electron microscopy, T4- and O1-like phages of Myoviridae and T1-like phage of Siphoviridae were isolated. Compared to T1- and O1-like phages, T4-like phages exhibited a broad host range and strong lytic capability when targeting E. coli O157:H7. Moreover, the T4-like phages were more frequently isolated from feces of LS than SS, suggesting that endemic phages may impact the shedding dynamics of E. coli O157:H7 in cattle.     

Development of novel chloroplast microsatellite markers for Cucumis from sequence database

The development of chloroplast microsatellite (cpSSR) markers in Cucumis species and analysis of their polymorphism and transferability were reported. Fifteen microsatellite markers, represented by mononucleotide repeats, were developed from the complete sequence of Cucumis sativus chloroplast genome. Intraspecific variation was successfully detected in C. sativus and C. melo and revealed mean 1.6 and 1.9 alleles per cpSSR locus, respectively. With the exception of two exon region-located cpSSR markers being monomorphic, each of the others amplified polymorphic fragments in C. sativus or C. melo. A total of 34 polymorphic loci were detected with these cpSSR markers in the two species. Transferability of the newly developed cpSSR markers was checked on an additional set of 41 Cucurbitaceae accessions (belonging to 12 different species), and except for two markers with no amplification in Cucurbita maxima, the others could be transferable to all the accessions tested. Of the 15 cpSSR markers, 14 markers generated fragments with expected band sizes and 13 markers detected interspecific polymorphism among the accessions. Intraspecific polymorphism was also observed within four Cucurbitaceae species excluding C. sativus and C. melo.     

Elevated CO2 concentration enhances the role of the ear to the flag leaf in determining grain yield of wheat

Net photosynthetic rate (P _N) of ear and flag leaf during grain filling stage and grain yield of plants with non-darkened or darkened flag leaf or darkened ear were examined in two different CO₂ concentrations: ambient (AC) and AC+200 μmol mol⁻¹ (EC). Ear showed much higher enhancement (56 %) of P _N than flag leaf (23 %) under EC. Moreover, CO₂ enrichment shortened the photosynthetic duration of flag leaf relative to ear. In this way the ratio of ear to flag leaf contribution to grain yield increased from 1.18 (AC) to 1.39 (EC).     

Isolation of mitochondrial DNA sequences that distinguish male-sterility-inducing cytoplasms in Sorghum bicolor (L.) Moench

We have demonstrated that sorghum DNA sequences of mitochondrial origin can be used to distinguish different male-sterility-inducing cytoplasms. Six DNA clones containing single-copy mitochondrial sequences were hybridized on Southern blots to restriction enzyme-digested DNA of 28 sorghum lines representing sources of different cytoplasmic male-sterility (CMS) groups. Four cytoplasmic types were defined on the basis of the pattern of DNA fragments detected. Similar analyses of 50 additional diverse sorghum accessions suggested that three of the four cytoplasmic types may be diagnostic for CMS. Also, three other cytoplasmic types were discovered. These and other mitochondrial DNA clones may be useful molecular tools for “fingerprinting” sterility-inducing cytoplasms in breeding programs, determining cytoplasmic diversity among germ plasm accessions, and identifying new sources of cytoplasm that induce male sterility.