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S Palmieri

Publications and source records attributed to S Palmieri.

69 records · Page 4Linked to original sources
PubMed1979

Protein synthesis in rabbit reticulocytes: mechanism of protein synthesis inhibition by heme-regulated inhibitor.

Partially purified Met-tRNAf binding factor, eIF-2, was phosphorylated by using heme-regulated inhibitor (HRI). Phosphorylated eIF-2 was freed from HRI by phosphocellulose column chromatography. Analysis by isoelectric focusing showed 100% phosphorylation of the 38,000-dalton subunit of eIF-2. Both eIF-2 and eIF-2(P) formed ternary complexes with Met-tRNAf and GTP with almost the same efficiency, and in both cases the ternary complex formation was drastically inhibited by prior addition of Mg2+. However, whereas the ternary complexes formed with eIF-2 could be stimulated by Co-eIF-2C at 1 mM Mg2+ and dissociated by Co-eIF-2B at 5 mM Mg2+, the ternary complexes formed with eIF-2(P) were unresponsive to both Co-eIF-2B and Co-e-IF-2C. Also, under conditions of eIF-2 phosphorylation, HRI drastically inhibited AUG-dependent Met-tRNAf binding to 40S ribosomes. However, HRI (in the presence of ATP) had no effect on the joining of preformed Met-tRNAf . 40S . AUG complex to the 60S ribosomal subunit to form Met-tRNAf-80S . AUG complex. These studies suggest that HRI inhibits protein synthesis initiation by phosphorylation of the 38,000-dalton subunit of eIF-2. HRI-phosphorylated eIF-2 does not interact with at least two other protein factors, Co-eIF-2B and Co-eIF-2C, and is thus inactive in protein synthesis initiation.

Animals↗
PubMed1978

Protein synthesis in rabbit reticulocytes: characteristics of a ribosomal factor that reverses inhibition of protein synthesis in heme-deficient lysates.

A ribosomal salt (0.5 M KCl) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of Met-tRNAfMet-binding factor (EIF-1), Co-EIF-1, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No direct correlation exists between amount of EIF-1 activity and ability to reverse inhibition of protein synthesis in heme-deficient lysates. Homogeneous preparations of EIF-1 are completely inactive in reversal of protein synthesis inhibition in heme-deficient lysates. These findings suggest that RF activity is not due to EIF-1 alone but may or may not require EIF-1 as a component of a complex factor.

Animals↗
PubMed1976

Protein synthesis in rabbit reticulocytes. Characteristics of mRNA (AUG codon)-dependent binding of Met-tRNAfMet to 40 S and 80 S ribosomes.

The characteristics of Met-tRNAfMet binding to ribosomes (40 S and 80 S) were studied using a two-stage assay method (Gupta, N.K., Chatterjee, B. and Majumdar, A. (1975) Biochem. Biophys. Res. Commun. 65, 797) and the complexes formed were analyzed either by Millipore filtration or by sucrose density gradient centrifugation. The results are summarized as follows: (a) with both assay methods, Met-tRNAfMet binding to 40 S ribosomes was entirely dependent upon addition of a partially purified mixture of initiation factors and AUG codon; (b) this binding occurred over a wide Mg2+ concentration range; significant binding was observed even at 20 mM Mg2+; (c) upon addition of 60 S ribosomes, a significant part of Met-tRNAfMet bound to 40 S ribosomes was transferred to 80 S complex. This transfer reaction had a sharp Mg2+ optimum around 2 mM. Met-tRNAfMet-80 S-AUG complex thus formed was active in Met-puromycin synthesis; (d) Met-tRNAfMet deacylase present in crude 0.5 M KCl ribosomal wash is a potent inhibitor of the binding reaction as it deacylates Met-tRNAfMet in the Met-tRNAfMet-40 S-AUG complex; (e) glutaraldehyde (0.5%) degrades Met-tRNAfMet-40 S-AUG complex but increases the background binding of Met-tRNAfMet to 40 S ribosomes in the absence of AUG codon; (f) polynucleotides containing uracil and adenosine are strong inhibitors of Met-tRNAfMet binding to 40 S ribosomes. The order of inhibitory activities of the polynucleotides tested was as follows: poly(rU)-poly(rA) (2:1) greater than poly(rU)-poly(rA) (1:1) greater than poly(rU) greater than poly(rA). Other RNAs tested such as poly(rC), poly(rI)-poly(rC) and phi6 bacteriophage RNA (double-stranded) were without significant effects on the Met-tRNAfMet-binding reaction.

Animals↗
PubMedDate not supplied

Isolation and some molecular properties of a trypsin-like enzyme from larvae of European corn borer Ostrinia nubilalis Hübner (Lepidoptera: Pyralidae).

A one-step high-yielding procedure is presented for the purification of a trypsin-like proteinase from Ostrinia nubilalis larvae, consisting of benzamidine-sepharose affinity chromatography. The purified enzyme was homogeneous as judged by SDS-PAGE. The enzyme presents a molecular mass of 24 650 Da, a maximum pH activity profile of 9.5, a remarkable thermal stability and an optimum temperature of about 53 degrees C Km values determined using N alpha-benzoyl-DL-arginine-ethylester and N alpha-benzoyl-DL-arginine-p-nitro-anilide were 3.2 x 10(-5) M and 4.1 x 10(-4) M respectively. The proteinase was inhibited by some typical serine proteinase inhibitors such as N alpha-tosyl-L-lysine chloromethyl ketone, soybean trypsin inhibitors, benzamidine and phenylmethylsulfonyl fluoride. In particular, it was competitively inhibited by benzamidine with a Ki of 1.2 x 10(-5) M, whereas it was not affected by cysteine proteinases inhibitors. Comparative analysis of the amino acid composition and N-terminal sequence of O. nubilalis proteinase confirmed that this enzyme is very similar to other serine proteinases from lepidopteran larvae.

Amino Acid Sequence↗
PubMedDate not supplied

A novel oligonucleotide probe for the detection of Newcastle disease virus.

An approach that possesses high specificity and broad applicability was used to obtain a DNA probe with potential diagnostic value. By utilizing synthesized oligonucleotide DNA, termed NDV probe, all 14 strains of NDV tested under high-stringency conditions were recognized in a slot-blot hybridization assay. The sequence of the NDV probe was generated from a highly conserved region of the NDV genome. No hybridization was observed with RNA isolated from other avian viruses, including avian influenza, infectious bursal disease, and infectious bronchitis. The specificity inherent in using an oligonucleotide probe offers advantages over probes obtained from cloned DNA fragments.

Animals↗
PubMedDate not supplied

Comparison of three velogenic strains of Newcastle disease virus by RNA oligonucleotide fingerprinting.

The purified RNA from three velogenic strains of Newcastle disease virus (Ca-1083 [Fontana], Largo, and Texas GB) was analyzed by oligonucleotide fingerprinting. An image-processing system used to manipulate and rescale autoradiographs to uniform dimensions assisted the manual comparison of RNA fingerprints. Based on this analysis, the fingerprints of the Largo and Ca-1083 viscerotropic strains were more similar to each other than either virus was to the Texas GB neurotropic strain. By contrast, the Largo and Texas GB strains displayed more differences in the pattern of RNA fragment migration than other strain comparisons. Fingerprint comparisons were also performed between velogenic and previously reported lentogenic strains of NDV. No large RNA fragments were identified as NDV-specific or virulence-specific. This study evaluates the relationships among these NDV strains.

Animals↗
PubMedDate not supplied

Cytopathic effect of lentogenic strains of Newcastle disease virus in cultured chicken muscle cells.

The ability of lentogenic strains of Newcastle disease virus (NDV) to inhibit the development of embryonic chicken muscle cells in vitro is described. In contrast to the uninfected control, which displayed a thick network of branched multinucleated muscle fibers, cultures infected with NDV exhibited a severely reduced potential to differentiate. The few differentiated muscle fibers that formed in the presence of NDV were poorly developed, displayed an attenuated morphology, and detached from the substrate 2 to 3 days before uninfected cultures showed signs of cell aging. When NDV-infected cultures were stained before muscle fiber detachment with a fluorescent-labeled NDV-specific antibody, the infected muscle fibers reacted strongly relative to neighboring myoblasts and fibroblasts. All six strains of NDV induced a similar inhibitory effect, and no strain-specific differences were detectable. These results indicate that differentiating muscle fibers are highly susceptible to infection by NDV in vitro and that this tissue exhibits an early NDV-induced cytopathic effect.

Animals↗
PubMedDate not supplied

An alternative method of oligonucleotide fingerprinting for resolving Newcastle disease virus-specific RNA fragments.

The technique of "RNA oligonucleotide fingerprinting" was adapted for the purpose of identifying genetic differences among strains of Newcastle disease virus (NDV). The specific method used for visualizing patterns of viral RNA fragments in two-dimensional polyacrylamide gels has several advantages over previously published procedures: It has low input radiation, high resolution, and low biohazard considerations. For demonstration purposes, the La Sota strain of NDV was fingerprinted. These initial results suggest that oligonucleotide mapping may provide an approach for correlating changes in the pathogenicity of NDV with the presence or absence of specific viral RNA sequences.

Animals↗
PubMedDate not supplied

In ovo competition between distinct virus populations in an avian influenza isolate.

Embryo lethality patterns induced by an avian influenza virus isolate (A/Tk/Ws/68/H5N9) suggested that it contained more than one genetic form. Two different virus populations were recovered from the isolate by plaque isolation and limit-dilution cloning and were characterized with respect to their biological and molecular properties. They were very closely related but exhibited strikingly different mean death times (MDT) in 10-day-old chick embryos. One was rapidly embryo lethal (REL), while the other was slowly embryo lethal (SEL). The REL isolate demonstrated a small but measurable mortality rate in 4-week-old chicks, as did the parental isolate. The SEL isolate, however, was nonlethal to 4-week-old chicks. The embryo MDT induced by the parental isolate revealed a biphasic death pattern reflecting expression of both REL and SEL populations. Mixing experiments, using different amounts of the two cloned populations, demonstrated that expression of their unique phenotypic property (either REL or SEL) was competitive. The number of early or late embryo deaths was directly related to the input levels of each respective virus. The only molecular difference thus far detected between the two populations is in the nonstructural (NS) gene, with the REL clone possessing a faster migrating electrophoretic form of that RNA than the SEL clone. Both forms of the NS gene were present in the original parental isolate. This study thus demonstrates the competitive coexistence of two closely related virus populations within a single natural isolate.

Animals↗
PubMedDate not supplied

Genetic relationships among lentogenic strains of Newcastle disease virus.

Purified RNA from five lentogenic Newcastle disease virus (NDV) strains (B1, England-F, Nebraska, Queensland V4, and Ulster) was subjected to oligonucleotide fingerprinting analysis. This technique could resolve over 100 oligonucleotides per virus strain, of which 50 to 80 were unique. Although the fingerprints generated from these viral RNAs exhibited similar distribution patterns of non-unique RNA fragments, all could be distinguished from one another on the basis of the migration of unique RNA fragments. It is concluded that oligonucleotide mapping is a useful method of unambiguously identifying individual lentogenic strains of NDV and that this technique may serve as a means of characterizing highly pathogenic NDV isolates.

Newcastle disease virus↗