Visible laser and UV-A radiation impact on a PNP degrading Moraxella strain and its rpoS mutant

The role of stationary phase sigma factor gene (rpoS) in the stress response of Moraxella strain when exposed to radiation was determined by comparing the stress responses of the wild-type (WT) and its rpoS knockout (KO) mutant. The rpoS was turned on by starving the WT cultures for 24 h in minimal salt medium. Under non-starved condition, both WT and KO planktonic Moraxella cells showed an increase in mortality with the increase in duration of irradiation. In the planktonic non-starved Moraxella, for the power intensity tested, UV radiation caused a substantially higher mortality rate than did by the visible laser light (the mortality rate observed for 15-min laser radiation was 53.4 +/- 10.5 and 48.7 +/- 8.9 for WT and KO, respectively, and 97.6 +/- 0 and 98.5 +/- 0 for 25 s of UV irradiation in WT and KO, respectively). However, the mortality rate decreased significantly in the starved WT when exposed to these two radiations. In comparison, rpoS protected the WT against the visible laser light more effectively than it did for the UV radiation. The WT and KO strains of Moraxella formed distinctly different types of biofilms on stainless steel coupons. The KO strain formed a denser biofilm than did the WT. Visible laser light removed biofilms from the surfaces more effectively than did the UV. This was true when comparing the mortality of bacteria in the biofilms as well. The inability of UV radiation to penetrate biofilms due to greater rates of surface absorption is considered to be the major reason for the weaker removal of biofilms in comparison to that of the visible laser light. This result suggests that high power visible laser light might be an effective tool for the removal of biofilms.     

Limited microsynteny between the genomes of Pristionchus pacificus and Caenorhabditis elegans

Nematodes are an attractive group of organisms for studying the evolution of developmental processes. Pristionchus pacificus was established as a satellite organism for comparing vulva development and other processes to Caenorhabditis elegans. The generation of a genetic linkage map of P.pacificus has provided a first insight into the structure and organization of the genome of this species. Pristionchus pacificus and C.elegans are separated from one another by >100 000 000 years such that the structure of the genomes of these two nematodes might differ substantially. To evaluate the amount of synteny between the two genomes, we have obtained 126 kb of continuous genomic sequence of P.pacificus, flanking the developmental patterning gene pal-1. Of the 20 predicted open reading frames in this interval, 11 have C.elegans orthologs. Ten of these 11 orthologs are located on C.elegans chromosome III, indicating the existence of synteny. However, most of these genes are distributed over a 12 Mb interval of the C.elegans genome and only three pairs of genes show microsynteny. Thus, intrachromosomal rearrange ments occur frequently in nematodes, limiting the likelihood of identifying orthologous genes of P.pacificus and C.elegans based on positional information within the two genomes.     

Quorum sensing modulators exhibit cytotoxicity in Hodgkin’s lymphoma cells and interfere with NF-κB signaling

In recent years it has become evident that bacteria can modulate signaling pathways in host cells through the secretion of small signaling molecules. We have evaluated the cytotoxic effects and NF-κB inhibitory activities of a panel of quorum sensing molecules and their reactive analogs on Hodgkin's lymphoma cells (L428). We found that several molecules inhibited NF-κB signaling in a dose dependent manner. Three inhibitors (ITC-12, ITC-Cl and Br-Furanone) showed 50% NF-κB inhibition at concentrations less than 10 µM (4.1 µM, 12.8 µM and 9.9 µM, respectively). Furthermore, all three molecules displayed cytotoxic effects against L428 cells with IC50 values of 12.4 µM, 18.3 µM and 3.1 µM respectively after 48 h incubation. They also showed inhibition of A549 adenocarcinoma cell migration at low concentrations 5.6 µM, 2.6 µM and 7.9 µM respectively. Further analysis showed that these molecules significantly decrease the degree of expression of proteins of NF-κB subunits p50, p65 and RelB both in cytosolic and nuclear fractions. This confirms that these compounds have the potential to modulate the NF-κB pathway by suppressing their subunits and thus exhibit cytotoxicity and inactivation of NF-κB signaling in Hodgkin's lymphoma cells.     

Capacity-speed relationships in prefrontal cortex

Working memory (WM) capacity and WM processing speed are simple cognitive measures that underlie human performance in complex processes such as reasoning and language comprehension. These cognitive measures have shown to be interrelated in behavioral studies, yet the neural mechanism behind this interdependence has not been elucidated. We have carried out two functional MRI studies to separately identify brain regions involved in capacity and speed. Experiment 1, using a block-design WM verbal task, identified increased WM capacity with increased activity in right prefrontal regions, and Experiment 2, using a single-trial WM verbal task, identified increased WM processing speed with increased activity in similar regions. Our results suggest that right prefrontal areas may be a common region interlinking these two cognitive measures. Moreover, an overlap analysis with regions associated with binding or chunking suggest that this strategic memory consolidation process may be the mechanism interlinking WM capacity and WM speed.     

Inactivation of phytotoxin produced by the rice sheath blight pathogen Rhizoctonia solani

The rice sheath blight pathogen, Rhizoctonia solani, produces a toxin designated as RS-toxin, a carbohydrate compound containing mainly alpha-glucose and mannose. Different microflora were tested for RS-toxin inactivation. Isolates of Trichoderma viride inactivated this toxin when it was provided as the sole food source, and these isolates reduced the severity of toxin-induced symptoms and electrolyte leakage from rice cells. The best-performing isolate, TvMNT7, produced two extracellular proteins of 110 and 17 kDa. The high molecular mass protein was shown to have alpha-glucosidase activity. The purified 110 kDa protein was able to reduce RS-toxin activity.     

Agrobacterium-Mediated Transformation of Switchgrass and Inheritance of the Transgenes

Switchgrass (Panicum virgatum L.) has been developed into an important biofuel crop. Embryogenic calli induced from caryopses or inflorescences of the lowland switchgrass cultivar Alamo were used for Agrobacterium-mediated transformation. A chimeric hygromycin phosphotransferase gene (hph) was used as the selectable marker and hygromycin as the selection agent. Embryogenic calli were infected with Agrobacterium tumefaciens strain EHA105. Calli resistant to hygromycin were obtained after 5 to 8 weeks of selection. Soil-grown transgenic switchgrass plants were obtained 4 to 5 months after Agrobacterium infection. The transgenic nature of the regenerated plants was demonstrated by PCR, Southern blot hybridization analysis, and GUS staining. T1 progeny were obtained after reciprocal crosses between transgenic and untransformed control plants. Molecular analyses of the T1 progeny revealed various patterns of segregation. Transgene silencing was observed in the progeny with multiple inserts. Interestingly, reversal of the expression of the silenced transgene was found in segregating progeny with a single insert.     

Microfouling studies on experimental test blocks of steel-making slag and concrete exposed to seawater off Chiba, Japan

Microfouling studies with the emphasis on microalgae (Bacillariophyceae) were carried out on test blocks of steel-making slag in comparison with concrete. Two types of slag test blocks, with and without fly-ash as an additional source of silica, and concrete test blocks of size 75 x 26 x 26 mm were used to study microfouling build-up for a period of 30 d, with intermittent samplings after 1, 2, 3, 7, 14 and 21 d. The species composition, cell density, biomass and surface pH of the test pieces were determined, in addition to the hydrographic parameters of the water column. Microfouling studies showed higher numbers of algal species as well as a greater cell density on the slag than on the concrete blocks. This was true with respect to biomass measured as dry weight also. Colonization was significantly delayed in the case of concrete. Navicula spp. and Nitzschia spp. were the initial colonizers on all three types of substrata and were the dominant genera throughout the study period. While the number of species increased, several disappeared after colonization, as a part of community build-up. The surface pH of the slag blocks was near neutral, whilst that of the concrete was highly alkaline during the initial period of exposure. This alkaline surface reduced the rate of species colonization on the concrete blocks initially. The study showed severe biofouling on the slag blocks compared to concrete and thus they were considered an environmentally benign construction material for land protection. The use of slag as the construction material for land protection would greatly reduce the expense compared to concrete.     

Bacterial destruction of mica during bioleaching of kaolin and quartz sandsby Bacillus cereus

Growth and metabolic activities of Bacillus cereus were found to cause the extraction of iron atoms from the octahedral position in mica in the kaolin sample (49%) and in the quartz sands sample (17%) after 3 months of bioleaching, while aluminium removal was only 5%. Mica destruction was detected in kaolin and quartz sands samples by X-ray diffraction analysis and also by i.r. adsorption spectroscopy in quartz sands samples. The structural changes obtained were confirmed by scanning electron microscopy (SEM) analysis. The SEM pictures show a different morphology in the boundary region of mica grains before and after bioleaching. Bacterial destruction effects were feeble in the interlayer sites and were specially directed to split planes, which are occupied by a number of bacterial cells. The biological destruction of mica with phengite composition after iron removal led to development of illite, which was detected by energy-dispersion microanalysis (EDS). Illite development caused also the enrichment of the kaolin sample by fine-grained fraction.     

Integrated flow-injection processing for on-line quantification of plasmid DNA during cultivation of E. coli

An integrated flow-injection processing (FIP) system for the quantification of plasmids during cultivation is described. The system performs on-line sampling, cell lysis, and quantification of plasmids in an integrated manner during cultivation of E. coli. The system was operated by using a miniaturized expanded-bed column which can be used for handling samples containing cells and cell debris without interfering with the binding analysis. Two types of detectors (one measuring UV absorbance at 254 nm and a fluorometer) are used for on-line plasmid detection. The system was developed using standard solutions and it was successfully applied in monitoring plasmid contents during a cultivation of E. coli.