Structure of the human neutrophil elastase gene

The gene for human neutrophil elastase (NE), a powerful serine protease carried by blood neutrophils and capable of destroying most connective tissue proteins, was cloned from a genomic DNA library of a normal individual. The NE gene consists of 5 exons and 4 introns included in a single copy 4-kilobase segment of chromosome 11 at q14. The coding exons of the NE gene predict a primary translation product of 267 residues including a 29-residue N-terminal precursor peptide and a 20-residue C-terminal precursor peptide. Analysis of the N-terminal peptide sequence suggests it contains a 27-residue "pre" signal peptide followed by a "proN" dipeptide, similar to that of other blood cell lysosomal proteases. The sequences for the mature 218-residue NE protein are included in exons II-V. The 5'-flanking region of the gene includes typical TATA, CAAT, and GC sequences within 61 base pairs (bp) of the cap site. The sequence 1.5 kilobases 5' to exon I contains several interesting repetitive sequences including six tandem repeats of unique 52- or 53-bp sequences. The 5'-flanking region also contains a 19-bp segment with 90% homology to a segment of the 5'-flanking region of the human myeloperoxidase (MPO) gene, a gene also expressed in bone marrow precursor cells and a protein stored in the same neutrophil granules as NE. In addition, like the MPO gene, the NE 5'-flanking region has several regions with greater than or equal to 75% homology to sequences 5' to c-myc, but there is no overlap between the NE-c-myc and MPO-c-myc homologous sequences.     

Temperature control of germination and its possible role in the survival of a non-dormant population of Avena fatua

Germination of freshly harvested seeds of a non-dormant (ND) line (Stonehouse 319) of wild oats ( Avena fatua L.) was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C. The germination inhibition in these seeds appeared to be a case of thermo-inhibition which was the direct effect of hightemperature treatment (HIT), since it did not persist after transferring the seeds to an optimum germination temperature of 20°C. Even a prolonged HTT of 30°C for over 5 weeks did not prevent germination of about 80% of the seeds transferred to 20°C. However, in a significant proportion of the seeds, thermo-dormancy was induced by 10 days of HTT at 30°C if the seeds were then incubated at sub-optimal temperatures of 5 to 15°C. This thermo-dormancy would appear to be 'restrictive' in form, since its expression was restricted to very specific conditions. Relatively low inclubation temperaturs of 5 and 10°C markedly slowed germination whether HTT was applied or not. The results suggest that thermo-inhibition and thermo-dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds of such ND lines as Stonehouse 319.     

Maintenance of the cellobiose utilization genes of Escherichia coli in a cryptic state

The genes for cellobiose utilization are normally cryptic in Escherichia coli. The cellobiose system was used as a model to understand the process by which silent genes are maintained in microbial populations. Previously reported was (1) the isolation of a mutant strain that expresses the cellobiose-utilization (Cel) genes and (2) that expression of those genes allows utilization of three beta- glucoside sugars: cellobiose, arbutin, and salicin. The Cel gene cluster has now been cloned from that mutant strain. In the course of locating the Cel genes within the cloned DNA segment, it was discovered that inactivation of the Cel-encoded hydrolase rendered the host strain sensitive to all three beta-glucosides as potent inhibitors. This sensitivity arises from the accumulation of the phosphorylated beta- glucosides. Because even the fully active genes conferred some degree of beta-glucoside sensitivity, the effects of cellobiose on a series of five Cel+ mutants of independent origin were investigated. Although each of those strains utilizes cellobiose as a sole carbon and energy source, cellobiose also acts as a potent inhibitor that reduces the growth rate on glycerol 2.5-16.5-fold. On the other hand, wild-type strains that cannot utilize cellobiose are not inhibited. The observation that the same compound can serve either as a nutrient or as an inhibitor suggests that, under most conditions in which cellobiose will be present together with other resources, there is a strong selective advantage to having the cryptic (Cel0) allele. In those environments in which cellobiose is the sole, or the best, resource, mutants that express the genes (Cel+) will have a strong selective advantage. It is suggested that temporal alternation between these two conditions is a major factor in the maintenance of these genes in E. coli populations. This alternation of environments and fitnesses was predicted by the model for cryptic-gene maintenance that was previously published.      

The structure and biological activities of the widely used protein kinase inhibitor, H7, differ depending on the commercial source.

The protein kinase inhibitor 1-(5'-isoquinolinesulfonyl)-2-methylpiperazine (H7) has been widely used because of its ability to inhibit cyclic AMP- and cyclic GMP-dependent protein kinases (PKA and PKG) and protein kinase C (PKC) at roughly equal concentrations; it is much less potent on other kinases. Previous studies in other laboratories have found that H7 samples from different commercial sources have different properties in cellular studies and protein kinase C inhibition assays. We now report the results of chemical and biological tests which show that H7 samples also differ in chemical structure, again depending on their commercial source. Chemical synthesis and NMR spectroscopy indicate that H7 from most suppliers has the structure originally proposed for H7, while "H7" from another supplier is in fact its 3-methylpiperazine positional isomer.     

Effect of ammonium sulfate on the phytotoxicity, foliar uptake, and translocation of imazamethabenz in wild oat

Experiments were conducted in greenhouse, growth chamber, and laboratory conditions to determine the effect of ammonium sulfate [(NH₄)₂SO₄] on the phytotoxicity, foliar uptake, and translocation of imazamethabenz on wild oat. Rates of (NH₄)₂SO₄ up to 5% (w/v) applied with a greenhouse sprayer did not affect the phytotoxicity of the herbicide when the mix was applied at the one- to two-leaf stage. However, inclusion of 1 and 2% (NH₄)₂SO₄ increased the phytotoxicity of the herbicide when the mix was sprayed at the two- to three-leaf, or the three- to four-leaf stage. At 10%, (NH₄)₂SO₄ decreased the phytotoxicity of the sublethal dosage of the herbicide. When the herbicide was applied as individual drops to the growth chamber-grown plants, inclusion of (NH₄)₂SO₄ at 1% did not affect phytotoxicity as measured by shoot growth. The presence of (NH₄)₂SO₄ did not affect the amount of imazamethabenz retained by wild oat foliage, but it decreased [¹⁴C]imazamethabenz absorption, slightly antagonized acropetal translocation, and increased the basipetal translocation of [¹⁴C]imazamethabenz. It was concluded that application methods greatly modify the effect of (NH₄)₂SO₄ on imazamethabenz phytotoxicity. Herbicide absorption and translocation as determined by one method do not necessarily represent the absorption and translocation patterns when different application methods are used. Absorption and translocation were not the factors that were responsible for the observed effect of (NH₄)₂SO₄ on the herbicide phytotoxicity.Abbreviations SC suspension concentrate