List Biological Laboratories, (List Labs) is a US biotechnology company producing bacterial toxins. Their products are involved in vaccine development, toxin research and infectious disease research worldwide.
We investigated geographic patterns of herbivory and resource allocation to defense, growth, and reproduction in an invasive biennial, Alliaria petiolata, to test the hypothesis that escape from herbivory in invasive species permits enhanced growth and lower production of defensive chemicals. We quantified herbivore damage, concentrations of sinigrin, and growth and reproduction inside and outside herbivore exclusion treatments, in field populations in the native and invasive ranges. As predicted, unmanipulated plants in the native range (Hungary, Europe) experienced greater herbivore damage than plants in the introduced range (Massachusetts and Connecticut, USA), providing evidence for enemy release, particularly in the first year of growth. Nevertheless, European populations had consistently larger individuals than US populations (rosettes were, for example, eightfold larger) and also had greater reproductive output, but US plants produced larger seeds at a given plant height. Moreover, flowering plants showed significant differences in concentrations of sinigrin in the invasive versus native range, although the direction of the difference was variable, suggesting the influence of environmental effects. Overall, we observed less herbivory, but not increased growth or decreased defense in the invasive range. Geographical differences in performance and leaf chemistry appear to be due to variation in the environment, which could have masked evolved differences in allocation.
The aim of this study was to investigate materials which reduce saliva-promoted adhesion of Streptococcus mutans onto enamel surfaces, and their potential in preventing dental biofilm development. The effects of hydroxyapatite (HA) surface pretreatment with hydrophilic polysaccharides on saliva-promoted S. mutans adhesion in vitro and de novo dental biofilm deposition in vivo were examined. Saliva-promoted adhesion of S. mutans MT8148 was significantly reduced by pretreatment of the HA surface with tragacanth gum (TG) and yeast-derived phosphoglycans. Extracellular phosphomannan (PM) from Pichia capsulata NRRL Y-1842 and TG reduced biofilm development on lower incisors in plaque-susceptible rats when administered via drinking water at concentrations of 0.5% and 0.01%, respectively. The inhibitory effect of TG on de novo dental biofilm formation was also demonstrated when administered via mouthwash in humans. It is concluded that TG and yeast-derived PM have the potential for use as anti-adherent agents and are effective in reducing de novo dental biofilm formation.
We compared intron-exon structures in 1,560 human-mouse orthologs and 360 mouse-rat orthologs. The origin of differences in intron positions between species was inferred by comparison with an outgroup, Fugu for human-mouse and human for mouse-rat. Among 10,020 intron positions in the human-mouse comparison, we found unequivocal evidence for five independent intron losses in the mouse lineage but no evidence for intron loss in humans or for intron gain in either lineage. Among 1,459 positions in rat-mouse comparisons, we found evidence for one loss in rat but neither loss in mouse nor gain in either lineage. In each case, the intron losses were exact, without change in the surrounding coding sequence, and involved introns that are extremely short, with an average of 200 bp, an order of magnitude shorter than the mammalian average. These results favor a model whereby introns are lost through gene conversion with intronless copies of the gene. in addition, the finding of widespread conservation of intron-exon structure, even over large evolutionary distances, suggests that comparative methods employing information about gene structures should be very successful in correctly predicting exon boundaries in genomic sequences.
Staphylococcus epidermidis is a frequent cause of infections associated with foreign bodies and indwelling medical devices. The bacteria are capable of surviving antibiotic treatment through encapsulation into biofilms. RNAIII-inhibiting peptide (RIP) is a heptapeptide that inhibits S. aureus pathogenesis by disrupting quorum-sensing mechanisms. In this study, RIP inhibited drug-resistant S. epidermidis biofilm formation through a mechanism similar to that evidenced for S. aureus. RIP is synergistic with antibiotics in eliminating 100% of graft-associated in vivo S. epidermidis infections, which suggests that RIP may be used to coat medical devices to prevent staphylococcal infections. Disruption of cell-cell communication can prevent infections associated with antibiotic-resistant strains.
BACKGROUND:Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances the Ig and TcR gene diversity in the N region at the junctions of variable (V), diversity (D) and joining (J) segments in B- and T-cells. TdT synthesizes the N region in concert with many proteins including DNA-PKcs, Ku70 and Ku86. To elucidate the molecular mechanism of the N region synthesis, we first attempted to isolate the genes with products that directly interact with TdT.RESULTS:Using a yeast two-hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 2 (TdIF2). The confined region of the C-terminal in TdIF2 is involved in specific interaction with the entire C-terminal in TdT. TdIF2 contains an acidic region comprised of 42 residues. TdIF2 was shown to bind specifically to a core histone by pull down assay using specific antibodies against TdIF2. When a TdT/TdIF2 complex was applied on to a DNA-cellulose column, only TdT bound to the column while TdIF2 passed through. TdIF2 reduces the TdT activity to 46% of its maximum value in vitro assay system using activated DNA as primer.CONCLUSIONS:TdIF2 binds directly to TdT and core histone. Furthermore, TdT, TdIF2 and core histone form a ternary complex. TdIF2 liberates H2A/H2B from a core histone in correlation with PCNA. The enzymatic consequence of the TdIF2/TdT complex is the reduction of TdT activity in vitro. TdIF2 would function as a chromatin remodeling protein at the N region synthesis.
