Knockdown of genes in the Toll pathway reveals new lethal RNA interference targets for insect pest control.

RNA interference (RNAi) is a promising alternative strategy for ecologically friendly pest management. However, the identification of RNAi candidate genes is challenging owing to the absence of laboratory strains and the seasonality of most pest species. Tribolium castaneum is a well-established model, with a strong and robust RNAi response, which can be used as a high-throughput screening platform to identify potential RNAi target genes. Recently, the cactus gene was identified as a sensitive RNAi target for pest control. To explore whether the spectrum of promising RNAi targets can be expanded beyond those found by random large-scale screening, to encompass others identified using targeted knowledge-based approaches, we constructed a Cactus interaction network. We tested nine genes in this network and found that the delivery of double-stranded RNA corresponding to fusilli and cactin showed lethal effects. The silencing of cactin resulted in 100% lethality at every developmental stage from the larva to the adult. The knockdown of pelle, Dorsal-related immunity factor and short gastrulation reduced or even prevented egg hatching in the next generation. The combination of such targets with lethal and parental RNAi effects can now be tested against different pest species in field studies.

Anterior Z250 resin composite restorations: one-year evaluation of clinical performance.

The purpose of this practice-based study was to compare the clinical performance of a new universal composite resin material (Z250) used for Class III and V cavities in anterior teeth. Restorative materials (Z250 and Z100; 3 M ESPE) placed by six operators were used for a total of 150 restorations during the 6-month enrollment period. After 1 year, 141 restorations (76 Z250 and 66 Z100) were available and evaluated for overall quality, color match, marginal adaptation, surface appearance and the presence of secondary caries, using modified USPHS criteria. The overall quality was excellent for both materials and no significant changes were noted during the follow-up. None of the scores between the two materials were statistically significant. Major changes were seen in color match and surface appearance. At baseline, the color match of 71% of Z250 and 62% of Z100 was rated as Alfa, after 1 year the figures were 60 and 65%. Regarding surface appearance, 97% of the Z250 were rated Alfa at baseline, whereas at 1 year the figure was 76%. For Z100, the scores were 94 and 79%, respectively. After 1 year, the clinical performance of Z250 restorative composite resin was clinically acceptable and similar to that of Z100.

Clinical survey of acrylic resin removable denture repairs with glass-fiber reinforcement.

PURPOSE: The aim of this study was to evaluate clinical usefulness and durability of continuous glass-fiber reinforcement in repair of acrylic resin removable dentures. MATERIALS AND METHODS: Fractured removable dentures without reinforcement, with conventional metal-wire reinforcement, or with mesh reinforcement were collected from two dental schools in Finland. The total number of dentures was 51 and the number of patients was 48. During the repair, the dentures were reinforced with a polymer-preimpregnated E-glass fiber at the region of the fracture. The fibers were used as partial fiber reinforcement, i.e., only the weakest part of the denture was reinforced. Follow-up time varied from 4 months to 4.1 years. After the follow-up period, possible fractures and discoloring were visually inspected. Possible irritation of oral mucosa by glass fibers and the general shape of the denture were also evaluated. RESULTS: In 88% of the cases, there was no need for adjustment at the region of partial fiber reinforcement, and the clinical condition of the dentures was good. Glass fibers did not irritate the oral mucosa. In the case of refracture or hairline fracture, positioning of the partial fiber reinforcement was incorrect or the reinforcement had been used incorrectly (the wetting of the reinforcement with denture base resin was inadequate). CONCLUSION: Polymer-preimpregnated partial fiber reinforcement seems to be useful in eliminating fractures of acrylic resin removable dentures. However, this study emphasizes the importance of correct positioning and accurate laboratory technique when partial fiber reinforcement is used.

Insecticidal proteins from Bacillus thuringiensis protect corn from corn rootworms.

Field tests of corn co-expressing two new delta-endotoxins from Bacillus thuringiensis (Bt) have demonstrated protection from root damage by western corn rootworm (Diabrotica virgifera virgifera LeConte). The level of protection exceeds that provided by chemical insecticides. In the bacterium, these proteins form crystals during the sporulation phase of the growth cycle, are encoded by a single operon, and have molecular masses of 14 kDa and 44 kDa. Corn rootworm larvae fed on corn roots expressing the proteins showed histopathological symptoms in the midgut epithelium.

Water sorption, solubility and effect of post-curing of glass fibre reinforced polymers.

Different polymer matrices are used for dental glass fibre composites. The aims of this study were to determine water sorption and solubility of glass fibre composites with different polymer matrices. In addition, the effect of post-curing of matrix polymers with heat on the water sorption and solubility values was investigated. Commercial one-phase and two-phase (powder-liquid) monomer systems were used in polymer matrix of E-glass fibre composite. Rhombic unreinforced and fibre reinforced test specimens were polymerized by autopolymerization or by light only, or additionally post-cured with heat. Water sorption and solubility determination method was based on ISO/DIS 1567-1997 draft for international standard with 7 d immersion time. In addition, water sorption was measured at second time for 30 d immersion time to determine saturation time of test specimens by water. Five test specimens of unreinforced polymer and reinforced polymer were tested and the quantity of fibres was determined by combustion analysis. Water sorption values of different brands of polymer matrices ranged from 0.9 to 8.3 wt% (P < 0.001, ANOVA). High sorption values were explained by microscopic voids in the polymer matrix and by composition of polymer matrix. Solubility values ranged from 0.02 to 2.5 wt% (P < 0.001, ANOVA). Generally, fibre inclusion and post-curing of polymer matrix reduced water sorption and solubility. The results of this study suggest that the water sorption and solubility of fibre composites varies according to the brand of polymer matrix and homogenity of polymer matrix. Water sorption of polymer matrix might influence hydrolytic stability of polymer-glass fibre composite.

Impact strength of a modified continuous glass fiber--poly(methyl methacrylate).

The effect of fiber reinforcement of autopolymerizing poly(methyl methacrylate) was investigated. The impact strength of continuous E-glass fiber-poly(methyl methacrylate) composite was determined. Rectangular test specimens (n = 10 per group) were modified by incorporating an additional fiber reinforcement of untreated E-glass fibers, silanized E-glass fibers, or aramid fibers in the test specimens. Controls were either unreinforced or reinforced from the middle of the test specimen only. The impact strength of the specimens was measured by using a charpy-type pendulum impact tester after the specimens had been stored in water at 37 degrees C for 4 weeks. After the impact strength test, the length of the delamination of poly(methyl methacrylate) from the fibers was measured and plotted to the impact strength of the test specimens by using a linear regression model. The impact strength of unreinforced autopolymerizing poly(methyl methacrylate) was 7.8 kl/m2, while incorporation of glass fiber reinforcement with a fiber concentration of 12.4 wt% increased the impact strength to 74.7 kl/m2 (P = .000). The additional fiber reinforcement of the test specimen did not affect the impact strength (P = .363). Delamination negatively correlated with the impact strength of the test specimens (r = -.72, P = .000). The results of this study suggest that glass fiber reinforcement enhanced the impact strength of autopolymerizing poly(methyl methacrylate), while the use of additional fiber reinforcement made of aramid or glass fibers in the test specimens did not have an effect on the impact strength.

New classes of Streptomyces coelicolor A3(2) mutants blocked in undecylprodigiosin (Red) biosynthesis.

Fifteen mutants of Streptomyces coelicolor A3(2) blocked in both the bipyrrole branch (redA) and a second site specific to the undecylprodigiosin pathway were characterized. Some of the mutants were ordered biosynthetically based on cosynthesis experiments. Complementation of each of the mutants with wild-type DNA cloned in low- and high-copy number plasmid vectors allowed the mutants to be separated into 12 new classes which are physically clustered within approximately 37 kb on the S. coelicolor genome. Early-step biosynthetic genes are centrally located and are flanked by later-step and regulatory genes.

Nucleotide sequence and transcriptional analysis of the redD locus of Streptomyces coelicolor A3(2).

Previous genetic evidence suggested that the redD gene product might be involved in the regulation of undecylprodigiosin (Red) biosynthesis in Streptomyces coelicolor. The redD+ gene was subcloned on a 2.2-kilobase-pair restriction fragment from the S. coelicolor redCD region by complementation of S. coelicolor JF1 (redD42). The DNA sequence of the 2.2-kilobase-pair redD-complementing region was determined, and the redD coding sequence was identified by computer analysis and deletion subcloning. Transcription at the redD locus was analyzed by using in vivo promoter probing, high resolution S1 mapping, and in vitro runoff transcription. A face-to-face arrangement of promoters was deduced, in which the proposed redD promoter was opposed by a cluster of four other promoters for another unidentified open reading frame. In time course experiments, redD transcription preceded that at two biosynthetic loci, redE and redBF; transcription at the latter two loci was reduced in redD42 mutants. The putative redD polypeptide lacked any strong sequence similarities to other known proteins.

The amino acid sequence of the eukaryotic DNA [N6-adenine]methyltransferase, M.CviBIII, has regions of similarity with the prokaryotic isoschizomer M.TaqI and other DNA [N6-adenine] methyltransferases.

The sequences of the genes coding for M.CviBIII (from virus NC-1A which infects a eukaryotic alga) [Narva et al., Nucleic Acids Res. 15 (1987) 9807-9823] and M.TaqI (from the bacterium Thermus aquaticus) [Slatko et al., Nucleic Acids Res. 15 (1987) 9781-9796] have been determined recently. Both enzymes methylate adenine in the sequence TCGA. We have compared the predicted amino acid sequences of these two methyltransferases (MTases), with each other and with ten other N6 A-MTases and find regions of similarity. M.CviBIII and M.TaqI were most closely related followed by M.PaeR7, whose recognition sequence (CTCGAG) contains the M.TaqI/M.CviBIII recognition sequence TCGA, and M.PstI, whose recognition sequence is CTGCAG. All of the N6-MTases contain the sequence Asp/Asn-Pro-Pro-Tyr (B-P-P-Y) referred to by Hattman et al. [J. Bacteriol. 164 (1985) 932-937] as region IV. The predicted secondary structure of this region forms a finger-like structure ('beta finger') containing a beta-pleated sheet (...XXXB), two beta-turns (P-P) followed by another beta-pleated sheet [Y/FXXX...].

Molecular cloning and characterization of the gene encoding the DNA methyltransferase, M.CviBIII, from Chlorella virus NC-1A.

The gene encoding the DNA methyltransferase, M.CviBIII, from Chlorella virus NC-1A was cloned and expressed in E. coli plasmid pUC8. Plasmid (pNC-1A.14.8) encoded M.CviBIII methylates adenine in TCGA sequences both in vivo in E. coli and in vitro. Transposon Tn5 mutagenesis localized the M.CviBIII functional domain to a 1.5 kbp region of pNC-1A.14.8 and also indicated that a virus promoter directs transcription of the gene in E. coli. The 2.1 kbp insert containing the M.CviBIII gene was sequenced and a single open reading frame of 1131 bp was identified within the domain determined by Tn5 mutagenesis. When the M.CviBIII gene was fused in-frame with the 19 amino-terminal codons of lacZ a 45 kD polypeptide was identified in maxicells as predicted by the DNA sequence. The M.CviBIII gene was not essential for virus replication since a virus M.CviBIII deletion mutant also replicated in Chlorella.