Parameters influencing translational efficiency in aphthovirus IRES-based bicistronic expression vectors

9 cases initially suspected of toxic nodular disease were proved to be Hodgkin disease in 8 and lymphoma in one. Sonographic exams of the neck revealed enlarged peri-thyroid nodes in all cases. Biopsy of these nodes and histopathological examinations of the nodes confirmed the diagnosis.     

A ribosomal protein is required for translational regulation of GCN4 mRNA. Evidence for involvement of the ribosome in eIF2 recycling

In amino acid-starved yeast cells, inhibition of the guanine nucleotide exchange factor eIF2B by phosphorylated translation initiation factor 2 results in increased translation of GCN4 mRNA. We isolated a suppressor of a mutant eIF2B. The suppressor prevents efficient GCN4 mRNA translation due to inactivation of the small ribosomal subunit protein Rps31 and results in low amounts of mutant 40 S ribosomal subunits. Deletion of one of two genes encoding ribosomal protein Rps17 also reduces the amounts of 40 S subunits but does not suppress eIF2B mutations or prevent efficient GCN4 translation. Our findings show that Rps31-deficient ribosomes are altered in a way that decreases the eIF2B requirement and that the small ribosomal subunit mediates the effects of low eIF2B activity on cell viability and translational regulation in response to eIF2 phosphorylation.     

Ribosomes from Xenopus laevis eggs and embryos in a cell-free protein-synthesizing system: translational regulation

Three types of ribosomal preparations from Xenopus laevis eggs and embryos were tested in a cell-free system to study possible translational regulation of protein synthesis as mediated by the ribosome during early amphibian development: type 1, a crude high-speed sediment, mainly containing monoribosomes completely dissociable by 0.5 M KC1; type II, ribosomes washed with 0.5 M KC1; and type III, ribosomes treated with puromycin - 0.5 M KC1. All three types showed an active response to the addition of poly[U]. Type III was found to be the most active: levels of incorporation of 30 phenylalanine residues/ribosome were reached. In all three cases ribosomes prepared from unfertilized eggs were 30-40% less active in vitro than those from cleavage and gastrula stages.     

A new factor from Escherichia coli affects translocation of mRNA

Reconstitution of protein synthesis from purified translation factors on ribosomes from Escherichia coli has revealed the requirement for a protein, W, that affects chain elongation and is essential to reconstitute the process (Ganoza, M. C., Cunningham, C., and Green, R. M. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 1648-1652). We report that W has no effect on initiation complex formation by 30 or 70 S ribosomes or on the association of ribosomal subunits, peptide bond synthesis, or binding Ala-tRNA, which is the second amino acid of the coat protein of the MS2 RNA virion. W has a pronounced effect on tripeptide synthesis, and is obligatory for the synthesis of the coat protein or of the hexapeptide encoded by f2am3 RNA. Extracts from a temperature-sensitive mutant of the translocase, EF-G, were purified free of the W protein and were used to score for translocation defects. W is required for binding Ser-tRNA, the third N-terminal amino acid of the MS2 or f2 RNA coat protein to ribosomes bearing fMet-Ala-tRNA, as well as for the ejection of deacyl-tRNA from ribosomes, which occurred concomitant with the binding of the Ser-tRNA. We propose that W functions by ejecting tRNAs from ribosomes in a step that precedes the movement of mRNA during translocation.     

A method for identifying splice sites and translational start sites in eukaryotic mRNA

History of the IInd Gynaecological and Obstetric Clinic of 1st Faculty of Medicine, Charles University in Prague is recorded here from its establishment in 1920 to the end of World War II. The activities of the Clinic are depicted in characterization of prominent personalities who worked here in this period. The characterization is focussed mostly on head physicians and their clinical, pedagogical and scientific activities and their works published.     

Indirect regulation of translational termination efficiency at highly expressed genes and recoding sites by the factor recycling function of Escherichia coli release factor RF3

Prokaryotic release factor RF3 is a stimulatory protein that increases the rate of translational termination by the decoding release factors RF1 and RF2. The favoured model for RF3 function is the recycling of RF1 and RF2 after polypeptide release by displacing the factors from the ribosome. In this study, we have demonstrated that RF3 also plays an indirect role in the decoding of stop signals of highly expressed genes and recoding sites by accentuating the influence of the base following the stop codon (+4 base) on termination signal strength. The efficiency of decoding strong stop signals (e.g. UAAU and UAAG) in vivo is markedly improved with increased RF3 activity, while weak signals (UGAC and UAGC) are only modestly affected. However, RF3 is not responsible for the +4 base influence on termination signal strength, since prfC- strains lacking the protein still exhibit the same qualitative effect. The differential effect of RF3 at stop signals can be mimicked by modest overexpression of decoding RF. These findings can be interpreted according to current views of RF3 as a recycling factor, which functions to maintain the concentration of free decoding RF at stop signals, some of which are highly responsive to changes in RF levels.     

The regulation of collagen in fetal skin wounds: mRNA localization and analysis

The deposition of collagen in fetal skin wounds has been shown in several animal models. The authors used a radiolabeled RNA antisense probe, complementary to the mRNA for the alpha-1 chain of human procollagen type I, to assess regulation of this collagen species in fetal and adult rabbit wounds. Dorsal skin wounds were placed on fetal and maternal animals at the beginning of the third trimester, and were harvested 3, 5, and 7 days later. In situ RNA/RNA hybridization was performed on suitable specimens, and morphometric analysis was carried out with a computerized LECO image analyzer. Fetal wounds exhibited an inflow of mesenchymal cells that produced collagen type I at levels higher than the surrounding tissue; this activity was highest on days 3 and 5 after wounding. Adult wounds had increased fibroblast presence by day 7, producing collagen type I at levels higher than those of adjacent unwounded tissue. Morphometric analysis of the signal produced by in situ hybridization and of the number of cells producing the signal in a given field showed that fetal wounds appear to produce collagen type I by an increase in the number of cells in the area of the wound--not by induction of the gene for procollagen type I. In contrast, adult wounds had both fibroblast migration and induction of procollagen type I mRNA synthesis. These findings imply multilevel regulation of collagen production in the adult and posttranslational regulation in the fetus.     

Tissue-specific regulation of cytochrome c oxidase efficiency by nucleotides

Cytochrome c oxidase from bovine heart and liver was reconstituted in liposomes in the absence or presence of nucleotides. Intraliposomal ADP, and to a smaller extent intraliposomal ATP, increased the respiratory activity of the heart but not of the liver isozyme under uncoupled but not under coupled conditions, leading to increased respiratory control ratios. In a preceding publication [Anthony, G., Reimann, A., & Kadenbach, B. (1992) Proc. Natl. Acad. Sci. U.S.A. 90, 1652-1656], the stimulatory effect of intraliposomal ADP could be related to interaction with the matrix domain of subunit VIa-h (heart type). The data suggest a regulatory effect of matrix nucleotides in heart and skeletal muscle mitochondria on the efficiency of energy transduction in COX.     

Developmental readiness: Accelerating leader development.

The development of leaders is a stated goal of most organizations, yet a validated framework and theory for leader development does not yet fully exist, nor is there a method for determining who is developmentally ready to engage in leader development. The authors of this article provide a framework for examining how one can accelerate leader development. They propose that leader developers first focus on assessing and then building the developmental readiness of individual leaders, as well as the developmental readiness of the organization as prerequisite steps for accelerating positive leader development. They identify and discuss 5 specific constructs comprising their initial modeling of developmental readiness (i.e., learning goal orientation, developmental efficacy, self-concept clarity, self-complexity, and metacognitive ability), as well as suggest methods for assessing and developing these 5 components. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interleukin-4 and -13 inhibit tumor necrosis factor-alpha mRNA translational activation in lipopolysaccharide-induced mouse macrophages

The production of tumor necrosis factor-alpha (TNF-alpha) by lipopolysaccharide (LPS)-stimulated macrophages can be markedly inhibited by the two closely related cytokines, interleukin (IL)-4 and IL-13. To investigate the molecular mechanism of this inhibition, we analyzed the effect of the two cytokines on TNF-alpha production and TNF-alpha mRNA accumulation in the mouse macrophage cell lines RAW 264.7 and J774 stimulated by LPS. Whereas LPS-induced TNF-alpha production is strongly suppressed by both cytokines, TNF-alpha mRNA accumulation is not significantly affected, indicating that IL-4 and IL-13 induce a translational repression of TNF-alpha mRNA. Transfection of reporter gene constructs containing different regions of the TNF-alpha gene revealed that the inhibitory action of IL-4 and IL-13 is mediated by the UA-rich sequence present in the TNF-alpha mRNA 3'-untranslated region.     

UGA codon position affects the efficiency of selenocysteine incorporation into glutathione peroxidase-1

A UGA codon and a selenocysteine insertion sequence in the 3'-untranslated region are the only established mRNA elements necessary for selenocysteine (Sec or U) incorporation during translation. These two elements, however, do not universally confer efficient Sec incorporation. The objective of this study was to systematically examine the effect of UGA codon position on efficiency of Sec insertion. In a glutathione peroxidase-1 (F-GPX1) expression vector, the UGA at the native position (U47) was mutated to a cysteine codon, and codons for Ser-7, Ser-12, Ser-18, Ser-29, Ser-45, Ser-93, Cys-154, Val-172, Ser-178, and Ser-195 were individually mutated to UGA and transiently expressed in COS-7 cells. 75Se incorporation at the 11 positions was 31, 72, 54, 105, 90, 100, 146, 135, 13, 11, and 43%, respectively, of 75Se incorporation at U47, suggesting that Sec is more efficiently incorporated at UGA codons positioned in the middle of the coding region rather than close to the 5' or 3' ends. Ribonuclease protection showed that these differences were not due to differences in mRNA level. When the green fluorescence protein (GFP) coding region was placed in-frame at the 5' or 3' ends of the coding region in F-GPX1 to produce chimeric 50-51-kDa GFP/GPX1 proteins, Sec incorporation at UGA codons, formerly close to the 5' or 3' ends, was increased to levels comparable to the UGA at U47. Insertion of GFP after the UAA-stop was just as effective in increasing Sec insertion efficiency as GFP inserted before the stop. These studies used a recombinant expression model that incorporated Sec at non-native UGA codons at rates equal to those of endogenous glutathione peroxidase-1 and showed that the efficiency of Sec incorporation can be modulated by UGA position; Sec incorporation at high efficiency appears to require that the UGA be >21 nucleotides from the AUG-start and >204 nucleotides from the selenocysteine insertion sequence element.     

A single point mutation in the yeast TRP4 gene affects efficiency of mRNA 3' end processing and alters selection of the poly(A) site

The yeast TRP4 mRNA 3' end formation element is a bidirectional element which functions in both orien-tations in an artificial in vivo test system. In this study, the role of 3' end formation was analysed in the context of the entire TRP4 gene. The 3' untranslated region (3'UTR) of TRP4 was altered and changes were analysed for their influence on TRP4 gene expression. The 3'UTR in reverse orientation was fully functional and did not affect TRP4 gene expression. Exchanging the TRP4 3'UTR by the bidirectional ARO4 or the unidirectional GCN4 3' end formation element allowed efficient gene expression. Deletion of the entire TRP4 3'UTR resulted in 70% reduction of TRP4 mRNA and 50% reduced specific Trp4 enzyme activity in comparison to wild-type. A single point mutation within the TRP4 3'UTR caused the same effect on gene expression. This point mutation did not only affect the efficiency of 3' end formation, but also produced new poly(A) sites which were situated upstream of the wild-type poly(A) sites. Therefore this sequence motif in the TRP4 3'UTR acts simultaneously as both an efficiency and positioning element.     

The charismatic leader: Asset or liability?

Charismatic leaders have the ability to gain a following of persons who are willing to place personal gain secondary to the will and wishes of the leader. Such a charismatic situation has tremendous potential for good or evil. Therapy groups seem to be natural arenas for the charismatic situation. Group members often perceive their leaders as "more than" human, and this seems to serve some important function in the life of the group. The present author assesses the place of the charismatic leader, along with its assets and liabilities, in the practice of group psychotherapy. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)