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J H Weil

Publications and source records attributed to J H Weil.

At least 91 records · Page 5Linked to original sources
PubMed1980

The nucleotide sequences of the initiator transfer RNAs from bean cytoplasm and chloroplasts.

The initiator tRNAsMet from the cytoplasm and chloroplasts of Phaseolus vulgaris have been purified and sequenced. The sequence of bean cytoplasmic initiator tRNAiMet is : pA-U-C-A-G-A-G-U-m1G-m2G-C-G-C-A-G-C-G-G-A-A-G-C-G-U-m2G-G-U-G-G-G2-C-C-C-A-U-t6A-A-C-C-C-A-C-A-G-m7G-D-m5C-C-C-A-G-G-A-psi-C-G-m1A-A-A-C-C-U-Gm-G-C-U-C-U-G-A-U-A-C-C-AOH. The sequence of bean cytoplasmic tRNAiMet is almost identical to that of wheat germ and shows a high degree of homology with other cytoplasmic initiator tRNAs. The sequence of bean chloroplast initiator tRNAfMet is : pC-G-C-G-G-A-G-U-A-G-A-G-C-A-A-C-U-U-Gm-G-D-A-G-C-U-C-G-C-A-A-G-G-C-U-C-A-U-A-A-C-C-U-U-G-A-A-m7G-acp3U-U-A-C-G-G-G-T-psi-C-A-A-A-U-C-C-C-G-U-C-U-C-C-G-C-A-A- C-C-AOH. Bean chloroplast initiator tRNAfMet sequence shows procaryotic characteristics at the 5' end of the acceptor stem and in the TpsiC loop, but also contains some distinctive features.

Base Sequence↗
PubMed1979

Fractionation and identification of spinach chloroplast transfer RNAs and mapping of their genes on the restriction map of chloroplast DNA.

Spinach chloroplast 4S RNAs has been separated by two-dimensional polyacrylamide gel electrophoresis into about 35 species. After extraction from the gel, 27 of these RNA species were identified by aminoacylation as tRNAs specific for 16 amino acids. Individual tRNAs were labeled in vitro with 125I and hybridized to DNA fragments obtained by digestion of spinach chloroplast DNA with KpnI, PstI, SalI and XmaI restriction endonucleases. A minimum of 21 genes corresponding to tRNAs for 14 different amino acids have been localized on the restriction endonuclease cleavage site map of the DNA molecule. Of these, 15 genes corresponding to tRNAs for 12 amino acids are located in the larger of the two single-copy regions which separate the two inverted copies of the repeat region. Each copy of this repeat region contains a set of genes for the ribosomal RNAs and a gene for tRNA2Ile in the "spacer" sequence between the 16S and 23S ribosomal RNAs. The genes for tRNA1Ile, tRNA2Leu and tRNA3Leu also map in the repeat region, but outside the ribosomal DNA unit. At present, two more chloroplast tRNAs (for Pro and Lys) have been identified, but not mapped, while 4 unidentified 4S RNAs have been mapped in the large single-copy region of the DNA molecule. Evidence is presented that isoaccepting tRNA species can be transcripts from different loci.

Amino Acyl-tRNA Synthetases↗
PubMed1978

Methylation of yeast tRNAPhe by enzymes from cytoplasm, chloroplasts and mitochondria of Phaseolus vulgaris.

Pure yeast tRNAPhe was used as a substrate to compare the tRNA methylating activities in Phaseolus vulgaris cytoplasm, chloroplasts and mitochondria, in the presence of S-adenosyl[Me-3H]methionine. The resulting [Me-3H]-tRNAPhe was then analyzed, using the techniques of nucleotide sequence determination. Cytoplasmic and mitochondrial enzymes catalyze the methylation (into m5C) of C48 present in the extra-loop, while chloroplast enzyme preparations catalyze the modification (into m1A) of A14 present in the dihydrouridine loop of tRNAPhe.

Base Sequence↗
PubMed1978

Adaptation of the tRNA population of maize endosperm for zein synthesis.

Maize endosperm, 30 days after pollination is actively synthesizing zein, a storage protein containing high amounts of glutamine. leucine and alanine. Endosperm tRNAs have a higher accepting activity than embryo tRNAs for these three amino acids, but not for some other (control) amino acids. This increase in accepting activity is accompanied by a change in the distribution of the isoaccepting tRNA species corresponding to these three amino acids, but not of the isoacceptors corresponding to some other (control) amino acids. These results are in favor of the theory of functional adaptation of tRNA population.

Alanine↗
PubMed1976

Aminoacylation of Phaseolus vulgaris cytoplasmic, chloroplastic and mitochondrial tRNAsPro and tRNAsLys by homologous and heterologous enzymes.

The cytoplasmic prolyl-tRNA synthetase can be separated by hydroxyapatite chromatography, from the enzyme present in the chloroplasts and in the mitochondria (organellar enzyme). The cytoplasmic lysyl-tRNA synthetase can also be separated from the organellar enzyme. There are two tRNAsPro in the cytoplasm; they can be charged by the cytoplasmic enzyme, but not by the organellar enzyme or the Escherichia coli enzyme. Chloroplasts contain, in addition to the two cytoplasmic tRNAsPro, one chloroplast-specific tRNAPro, which is not recognized by the cytoplasmic enzyme, but can be charged by the organellar or the E. coli enzyme. Mitochondria contain, in addition to the two cytoplasmic tRNAsPro, two mitochondria-specific tRNAsPro, which are not recognized by the cytoplasmic enzyme, but can be charged by the organellar or the E. coli enzyme. There are two tRNAsLys in the cytoplasm. Both can be charged by the cytoplasmic enzyme, but one can be charged by the organellar or E. coli enzyme. Chloroplasts contain in addition to one cytoplasmic tRNALys, one chloroplast-specific tRNALys which can only be charged by the organellar or E. coli enzyme. Mitochondria contain, in addition to one cytoplasmic tRNALys, one mitochondria-specific tRNALys which can only be charged by the organellar or E. coli enzyme.

Amino Acyl-tRNA Synthetases↗
PubMed1975

Aminoacylation of Phaseolus vulgaris cytoplasmic, chloroplastic and mitochondrial tRNAsMet and of Escherichia coli tRNAsMet by homologous and heterologous enzymes.

Met-tRNA synthetase from Paseolus vulgaris cytoplasm could be separated from its chloroplastic or mitochondrial counterpart by DEAE-cellulose chromatography, but the Met-tRNA synthetase from the two latter organelles could not be distinguished using DEAE-cellulose, hydroxyapatite or CM-Sephadex chromatography. As revealed by reverse-phase chromatography, bean cytoplasm contains 2 tRNAsMet; only one is charged by chloroplast, mitochondrial or Escherichia coli Met-tRNA synthetase. Mitochondria contain, in addition to the 2 cytoplasmic tRNAsMet, 3 mitochondria-spedific tRNAsMet; 2 can be formylated by the mitochondrial or the E. coli transformylase; all 3 are charged by mitochondrial, chloroplastic or E, coli Met-tRNA synthetase; none is charged by the cytoplasmic enzyme. Chloroplasts contain, in addition to the 2 cytoplasmic tRNAsMet, 3 chloroplast-specific tRNAsMet, different from the mitochondrial tRNAsMet; one is formylatable by the chloroplastic or the E. coli transformylase; all 3 are charged by chloroplastic, mitochondrial or E. coli Met-tRNA synthetase; only one is charged by the cytoplasmic enzyme. Of the 3 E. coli tRNAsMet, only the formylatable species can be charged by bean cytoplasmic, chloroplastic or mitochondrial Met-tRNA synthetase.

Amino Acyl-tRNA Synthetases↗
PubMed1975

Aminoacylation of tRNA-Leu species from Escherichia coli and from the cytoplasm, chloroplasts and mitochondria of Phaseolus vulgaris by homologous and heterologous enzymes.

Leucyl-tRNA synthetase from Phaseolus vulgaris chloroplasts could be separated from its cytoplasmic counterpart upon chromatography on hydroxyapatite, but the cytoplasmic and mitochondrial leucyl-tRNA synthetases could not be distinguished. The tRNALeu species from the various plant cell compartments and from Escherichia coli were aminoacylated using either homologous or heterologous enzymes; the levels of aminoacylation and the profiles of the leucyl-tRNAs upon reverse-phase chromatography were studied. Cytoplasmic tRNALeu species could be aminoacylated by the cytoplasmic or by the mitochondrial enzymes and in both cases yielded two peaks upon reverse-phase chromatography (RPC-5). But they could not be charged by the chloroplast-specific or by the E. coli enzynes. Mitochondrial tRNALeu species could be charged by the mitochondrial or by the cytoplasmic enzymes and in both cases yielded four peaks upon reverse phase (RPC-5) chromatography. But they could not be aminoacylated using the chloroplast-specific or the E. coli leucyl-tRNA synthetases. Chloroplastic tRNALeu species can be divided into two classes: the first class contains four isoacceptor species which can be charged by the cytoplasmic or mitochondrial enzymes, but not by the chloroplast-specific or the E. coli enzymes; the second class contains three chloroplast-specific tRNALeu species which can be charged by the chloroplast-specific or the E. coli enzymes but not by the cytoplasmic or the mitochondrial enzymes. There are five isoacceptor tRNALeu species in E. coli; all are charged by the E. coli or the chloroplast-specific enzymes, while only one is aminoacylated by the plant cytoplasmic or mitochondrial enzymes.

Amino Acyl-tRNA Synthetases↗
PubMed1975

Aversive effects and retention impairment induced by acetoxycycloheximide in an instrumental task.

AXM, when subcutaneously injected during the first 3 min following the acquisition of a nondiscriminative instrumental learning task, induced an aversion for the food reinforcement which had been associated with the training situation and with the pharmacological treatment. The high number of nonreinforced responses preceding the first reinforced response(RR) that animals performed when tested 6 days after AXM treatment, was not due to forgetting of the lever significance, but to this aversion. Animals treated with AXM showed low levels of lever pressing response and long latencies for their first RR; this deficit did not seem only to be due to food reinforcement aversion; it disappeared, as well as food aversion, when food reinforcement which had been associated with the learning situation and to treatment, was added to the daily feeding regimen during treatment-test interval. It has been shown, moreover, that more than 90 percent of cerebral protein synthesis was inhibited during the 5 hr following subcutaneous AXM injection. These findings are interpreted as an indication that AXM does not affect memory consolidation of a non discriminative instrumental learning.

Animals↗
PubMed1975

Effects of changes in growth rate on the levels of several aminoacyl-tRNA synthetases in yeast.

When the growth rate of yeast cells is decreased (for instance by transferring the cells from a rich medium to a poor one, or when the cells enter the stationary phase, or when growth is inhibited by cycloheximide, or when valine is removed from the medium supporting growth of a valine-requiring mutant, or when a thermosensitive mutant is shifted to the non-permissive temperature) there is a decrease in the levels of the four aminoacyl-tRNA synthetases tested. Conversely, an increase in the growth rate is accompanied by an increase in the levels of the four enzymes. But when the growth rate is slowed down by decreasing the temperature of the medium, no effect on the levels of the aminoacyl-tRNA synthetases is observed. These results are consistent with the concept of "metabolic regulation" proposed by Parker and neidhardt.

Amino Acyl-tRNA Synthetases↗