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B Reiss

Publications and source records attributed to B Reiss.

At least 37 records · Page 2Linked to original sources
PubMed1996

Enhanced green fluorescence by the expression of an Aequorea victoria green fluorescent protein mutant in mono- and dicotyledonous plant cells.

The expression of the jellyfish green fluorescent protein (GFP) in plants was analyzed by transient expression in protoplasts from Nicotiana tabacum, Arabidopsis thaliana, Hordeum vulgare, and Zea mays. Expression of GFP was only observed with a mutated cDNA, from which a recently described cryptic splice site had been removed. However, detectable levels of green fluorescence were only emitted from a small number of protoplasts. Therefore, other mutations in the GFP cDNA leading to single-amino acid exchanges in the chromophore region, which had been previously studied in Escherichia coli, were tested in order to improve the sensitivity of this marker protein. Of the mutations tested so far, the exchange of GFP amino acid tyrosine 66 to histidine (Y66H) led to detection of blue fluorescence in plant protoplasts, while the exchange of amino acid serine 65 to cysteine (S65C) and threonine (S65T) increased the intensity of green fluorescence drastically, thereby significantly raising the detection level for GFP. For GFP S65C, the detectable number of green fluorescing tobacco (BY-2) protoplasts was raised up to 19-fold, while the fluorimetricly determined fluorescence was raised by at least 2 orders of magnitude.

Base Sequence↗
PubMed1996

RecA protein stimulates homologous recombination in plants.

A number of RecA-like proteins have been found in eukaryotic organisms. We demonstrate that the prokaryotic recombination protein RecA itself is capable of interacting with genomic homologous DNA in somatic plant cells. Resistance to the DNA crosslinking agent mitomycin C requires homologous recombination as well as excision repair activity. Tobacco protoplasts expressing a nucleus-targeted RecA protein were at least three times as efficient as wild-type cells in repairing mitomycin C-induced damage. Moreover, homologous recombination at a defined locus carrying an endogenous nuclear marker gene was stimulated at least 10-fold in transgenic plant cells expressing nucleus-targeted RecA. The increase in resistance to mitomycin C and the stimulation of intrachromosomal recombination demonstrate that Escherichia coli RecA protein is functional in genomic homologous recombination in plants, especially when targeted to the plant nucleus.

Agrobacterium tumefaciens↗
PubMed1995

T-DNA integrations in a new family of repetitive elements of Nicotiana tabacum.

A number of T-DNA insertions in the genome of Nicotiana tabacum were characterized. One class of integrations was found to have occurred in a new family of highly repetitive sequences. Three genomic regions (ecoA, ecoB, and ecoC) were isolated, all of which contain basic units of 180 bp, organized in direct tandem repeats. Several of the 180-bp elements contain an EcoRI recognition site within the repeating unit and are therefore named "eco repeats." All members of this family are weakly homologous in sequence to a previously described class of repeat elements which contained a BamHI site (HRS60 repeat family), which suggests that both groups of sequences are of common evolutionary origin. The allotetraploid genome of N. tabacum is presumed to originate from the hybridization of two diploid genomes. The HRS60 elements previously described have been found exclusively in the genome of one of the ancestors, N. sylvestris, and in N. tabacum itself. Our DNA hybridization data suggest that the eco elements originate from the genome of the other ancestor, N. tomentosiformis. Whereas the HRS60 elements are transcriptionally silent, at least some eco elements appear to be transcribed.

Base Sequence↗
PubMed1995

Reporter genes.

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Chloramphenicol O-Acetyltransferase↗
PubMed1991

[Survival rate analysis and clinical follow-up of tooth-colored restorations of CEREC].

A survival rate analysis of 426 CEREC restorations, made in a general dentistry practice, was carried out for a period of 3 years. 12 restorations were lost. Thus the Kaplan-Meier probability of survival decreased to 0.95 within 23 months. The mortality rates of restorations in molars and of restorations in premolars showed no significant difference. The patients assessed the treatment results in 96% of the cases as "good" or very good". In 4 cases chewing sensibility necessitated the reconstruction of the inlay restoration. With increasing observation time a reduced quality of the marginal integrity was found.

Composite Resins↗
PubMed1990

Isolation of a gene encoding a novel chloroplast protein by T-DNA tagging in Arabidopsis thaliana.

A recessive pale mutation, designated as cs, was identified by transferred-DNA (T-DNA)-mediated insertional mutagenesis in Arabidopsis thaliana. The pale mutation, cosegregating with the hygromycin resistance marker of the T-DNA, was mapped to the position of the ch-42 (chlorata) locus on chromosome 4. Lack of genetic complementation between cs and ch-42 mutants indicated allelism. Plant boundaries of the T-DNA insert rescued from the pale mutant were used as probes for the isolation of genomic and full-length cDNA clones of the wild-type cs gene. Transformation of the pale mutant with T-DNA vectors carrying these clones resulted in a normal green phenotype, thus demonstrating positive complementation of the T-DNA induced mutation. DNA sequence comparison of the cs mutant and its wild-type allele revealed that the T-DNA insertion occurred 11 bp upstream of the stop codon. A fusion protein, seven amino acids longer than its wild-type counterpart of Mr 46,251, is therefore synthesized in the pale mutant. Transcript analysis during dark-light transition, in vitro protein transport assay, and the absence of DNA sequence homology between cs and known genes indicates that the light regulated expression of the cs gene results in the synthesis of a novel chloroplast protein.

Alleles↗
PubMed1989

Effect of mutations on the binding and translocation functions of a chloroplast transit peptide.

We studied transport and binding to intact chloroplasts of 10 mutants in three regions of the transit peptide of a precursor to the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase [3-phospho-D-glycerate carboxy-lyase (transphosphorylating), E.C.4.1.1.39]. Transport was assayed in a reconstituted system using isolated pea chloroplasts and radioactively labeled precursor. Binding to the chloroplast envelope was assayed in a similar manner using chloroplasts pretreated with nigericin. Most mutants showed a dramatically decreased capacity of binding, although some of them transported relatively well. The accumulation of the mutant proteins inside the chloroplast as a function of time was examined. Although the authentic small subunit precursor was imported rapidly, uptake of most mutant precursors was considerably slower and continued until the last time point examined. In terms of assigning functions to individual regions, we found that at least the middle region and parts of the amino and the carboxyl termini of the transit peptide are more important for receptor binding than for translocation. A two-step processing mechanism has been postulated for the maturation of the small subunit precursor. This model predicts the occurrence of processing intermediates. When precursors carrying carboxyl-terminal deletions were presented to the chloroplast, no defined intermediates could be detected. Instead, a number of proteins, probably resulting from aberrant processing, accumulated simultaneously inside the chloroplasts.

Amino Acid Sequence↗
PubMed1988

Complete processing of a small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from pea requires the amino acid sequence Ile-Thr-Ser.

Chloroplast import and processing of two precursor proteins with mutations in the carboxyl-terminal region of the transit peptide were examined in vitro. Deletion mutations were introduced into the 57-amino acid transit peptide of a chloroplast protein, the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, from pea. A mutant, PSd48/57, in which nine carboxyl-terminal amino acids of the transit peptide had been deleted, was imported and processed to a series of 13- to 18-kDa polypeptides including the 14-kDa mature small subunit. In contrast, processing of a mutant, PSd45/57, in which an additional three amino acids had been removed, resulted in a series of polypeptides which did not include the mature small subunit. Whereas PSd48/57 was imported as efficiently as the wild-type precursor, import of PSd45/57 was only 25% as efficient as that of the authentic precursor. The mutant precursor proteins PSd48/57 and PSd45/57 are distinguished by a three-amino acid sequence, Ile-Thr-Ser, located in the carboxyl-terminal region of the transit peptide. We show that all or part of this sequence is required for correct processing.

Amino Acid Sequence↗
PubMed1987

Regions in the transit peptide of SSU essential for transport into chloroplasts.

Deletion mutations, 3-19 amino acids in size, were introduced into the transit peptide (57 amino acids) of a small subunit (SSU) of ribulose-1,5-bisphosphate carboxylase/oxygenase from pea. Transport of the authentic small subunit precursor (pSSU) and of the mutant pSSUs by isolated chloroplasts of pea was examined. We show that the transit peptide contains two different, separated functional regions. A deletion mutation in the central region of the transit peptide, a region purported to be important for function, barely affected transport. Changes in the amino-terminal region of the transit peptide appeared normal. A deletion mutation at the carboxy-terminus of the transit peptide interfered with both transport and processing. From the aberrant processing we suggest that pSSU is matured in more than one step, and that the maturation signal is located within the carboxy-terminal 16 amino acids. The methionine residue at the evolutionarily conserved cleavage site (cysteine-methionine) between the transit peptide and the mature protein is not essential processing.

Chloroplasts↗
PubMed1987

Effects of bile acids on carcinogen-exposed rat colon in organ culture and as subsequent long-term transplants.

Rat (F344) colon fragments in organ culture were exposed for 4 to 6 hours to carcinogens and then for 4 days to deoxycholic acid or fecal extracts containing a mixture of in vivo-produced bile acids from animals fed low- or high-fat diets. Following exposures during culture, the fragments were transplanted into the mammary fat pads of syngeneic rats. The transplanted fragments survived for at least 1 year with preservation of crypt architecture and with continued DNA and mucin synthesis. Exposure in culture to N-methyl-N'-nitro-N-nitrosoguanidine (CAS: 70-25-7) or N-methyl-N-nitrosourea (CAS: 684-93-5) resulted in hypercellularity, hyperplasia, and cellular atypia in the transplants; but, in contrast to transplants from colon adenocarcinomas, no tumors formed. Exposure in culture to deoxycholic acid subsequent to N-methyl-N-nitrosourea or N-methyl-N'-nitro-N-nitrosoguanidine resulted in greater cellular abnormalities in transplants. Exposure after N-methyl-N-nitrosourea to fecal extracts from rats on a high-fat diet also enhanced the pathologic changes, whereas similar extracts from rats on a low-fat diet did not alter the pathology resulting from N-methyl-N-nitrosourea or N-methyl-N'-nitro-N-nitrosoguanidine exposures. It is concluded that bile acids, including those formed in vivo, facilitate the expression of carcinogen-induced abnormalities in the colon mucosa.

Animals↗
PubMed1985

Polymyalgia rheumatica/giant cell arteritis in a Cambridge general practice.

The aim of this study was to establish the incidence and prevalence of polymyalgia rheumatica/giant cell arteritis in general practice. Patients with this disorder, whether previously diagnosed or not, were ascertained by using a questionnaire administered by interview, and all received full clinical and laboratory assessment. A total of 579 patients aged 65 and over was seen, and 19 (33/1000) had been diagnosed or developed symptoms within the previous eight years. Thus the calculated annual incidence in those aged 65 and over was about 4/1000. The figures from this first large scale study of polymyalgia rheumatica/giant cell arteritis in general practice are much higher than those from studies carried out in hospital. The questionnaire was effective in both identifying known cases of polymyalgia rheumatica/giant cell arteritis and detecting new cases. As this is a treatable disorder, it is important that doctors become aware of how common it is in elderly people.

Aged↗
PubMed1985

Translationally coupled initiation of protein synthesis in Bacillus subtilis.

The neomycin phosphotransferase gene (neo) from Transposon Tn5 is active in Gram-negative bacteria but silent in B. subtilis since it lacks an appropriate ribosome binding site for Gram-positive bacteria. Neo translation could be reactivated by coupling its initiation to the translational termination of the highly expressed beta-lactamase gene (penP) from B. licheniformis. This initiation occurred at the authentic neo start codon. Its efficiency was independent of the nucleotide sequence 5 to the neo gene, but strongly affected by the distance between the termination and initiation codon. It was the highest if both codons overlapped in the sequence ATGA. In B. licheniformis, a translationally coupled neo gene was inducible expressed as the penP gene demonstrating the potential of the technique to monitor the activity of expression units for which no direct assays exists.

Bacillus subtilis↗
PubMed1984

Protein fusions with the kanamycin resistance gene from transposon Tn5.

The gene for the neomycin phosphotransferase II (NPT II) from transposon Tn5 was fused at the amino or carboxy terminus to foreign DNA sequences coding for 3-300 amino acids and the properties of the fused proteins were investigated. All amino-terminal fusions examined conferred kanamycin resistance to their host cell, but profound differences in their enzymatic activity and stability were detected. Short additions to the amino terminus of the NPT II resulted in highly enzymatically active fusion proteins whereas long amino-terminal fusions often had to be proteolytically degraded to release active proteins. Fusions at the carboxy-terminal end of the NPT II protein did not always induce kanamycin resistance and their enzymatic activity depended more stringently on the nature of the junction sequence.

Base Sequence↗
PubMed1984

A comparison of different nutrient media and supplementation with dexamethasone for mouse colon organ culture.

Several complex nutrient media were compared for their effectiveness in maintaining viable and functional mouse colon mucosa in organ culture. The order of superiority for preserving survival of normal tissues for 14 days was: Williams' Medium E greater than Morgan's 199 greater than CMRL-1066 greater than Waymouth's MB 752/l greater than Eagle's MEM greater than Trowell's T8. The 3H-thymidine labeling index was highest in colon explants maintained in Morgan's 199 greater than Williams' Medium E greater than Waymouth's MB 752/l greater than CMRL-1066 greater than Eagle's MEM. However, the very high labeling produced by Morgan's 199 medium was abnormal in comparison to in vivo levels. Supplementation with 1.0 uM dexamethasone almost always improved crypt survival and maintained normal DNA synthetic activity.

Animals↗
PubMed1984

A new sensitive method for qualitative and quantitative assay of neomycin phosphotransferase in crude cell extracts.

A general method is described for the detection and quantification of low amounts of neomycin phosphotransferase in crude cell extracts. The assay is based on the electrophoretic separation of the enzyme from other interfering proteins and detection of its enzymatic activity by in situ phosphorylation of the antibiotic kanamycin. Both kanamycin and [gamma-32P]ATP acting as substrates are embedded in an agarose gel placed on the polyacrylamide gel containing the separated proteins. After the enzymatic reaction, the phosphorylated kanamycin is transferred to P81 phosphocellulose ion exchange paper and the radiolabeled kanamycin is visualised by autoradiography. With this method 1 ng of active enzyme can easily be detected. Both prokaryotic and eukaryotic cell extracts can be examined, and changes in the size of enzymatically active proteins can be determined.

Animals↗
PubMed1984

Inhibition of target tissue activation of N'-nitrosonornicotine and N-nitrosopyrrolidine by dietary components.

Twenty-one dietary and related chemicals have been evaluated for their potential inhibitory activities against the tumorigenic effects of N-nitrosopyrrolidine and N'-nitrosonornicotine using in-vitro metabolic assays in the target tissues, namely, rat liver microsomes and cultured rat oesophagus, respectively. Compounds studied include phenols, cinnamic acids, coumarins, isothiocyanates and indoles. Isothiocyanates were the most potent inhibitors of both nitrosamines in the acute studies, but were less active in chronic studies. This difference may be explained by the pharmacokinetic properties of these compounds. Phenols, cinnamic acids, coumarins and indoles were primarily inducers of N-nitrosopyrrolidine metabolism. The results suggest that isothiocyanates, in general, are the most promising chemicals for future study as protective agents against the carcinogenic effects of these nitrosamines.

Animals↗