Reporter gene expression upon stable transfection when only a TATA box or a TATA box plus Sp1 sites are present 5' to the gene

Episomal plasmids for stable transfection of mammalian cell cultures were constructed that have a G418-resistance (neo) gene immediately downstream of a highly truncated promoter. These plasmids had a function hygromycin-resistance gene (hyg) as a selectable marker. Surprisingly, in LTK- cells, but not HeLa cells, stably transfected with these BK virus-based plasmids having no promoter elements adjacent to the neo gene, readthrough transcription, probably from about 1 kb upstream, gave almost as efficient expression of the neo gene as of the hyg gene with a full-length promoter immediately upstream. When the transfecting plasmids contained Epstein-Barr virus (EBV) DNA sequences for episomal maintenance and had multiple Sp1 sites and a TATA box as the only promoter elements 5' to the neo gene, only about 3-9% of HeLa transfectants were G418 resistant (G418R). In transfections with analogous plasmids lacking these promoter elements 5' to the neo gene, no G418R colonies were seen. The establishment of the G418R phenotype probably required integration of plasmid DNA into favorable chromosomal sites and was aided by the presence of the TATA box plus Sp1 sites as a subminimal promoter. The absence of detectable G418-resistance in most of the HeLa transfectant clones obtained with EBV-type plasmids, even at a high plasmid copy number and even when a TATA box and six Sp1 sites were present immediately upstream of the neo gene, indicates that these elements do not suffice for appreciable gene expression in vivo and that this is a suitable model system for studying DNA rearrangements that can potentiate expression of the neo gene.

Screening method for cellulose biosynthesis inhibitors with herbicidal activity

A new screening method for inhibitors of cellulose biosynthesis is described. This method utilized three microbial strains; a cellulose-containing fungus Phytophthora, and a cellulose non-containing fungus Candida, and a bacterial strain of Acetobacter, a cellulose-producing acetic acid bacterium. The primary screen examined microbial cultures for selective growth inhibition against Phytophthora with no inhibition against Candida. The secondary screen tested for herbicidal activity. Thirdly, the active cultures were examined for their inhibition of cellulose biosynthesis by an Acetobacter strain. A screening trial with this new method led to the discovery of two microbial metabolites named phthoxazolin A and phthoramycin as new inhibitors of cellulose biosynthesis with herbicidal activity.

Frequent detection of bcl-2/JH translocations in human blood and organ samples by a quantitative polymerase chain reaction assay

Using an ultrasensitive assay involving the PCR, we have examined the frequency of a follicular lymphoma-associated translocation in peripheral blood from 132 individuals, most of whom were healthy blood donors. This translocation occurs between the bcl-2 proto-oncogene and the JH gene region and prolongs the life of lymphocytes. At a level of sensitivity of 1 translocation-bearing cell per 5 x 10(6) cells, almost one-half of healthy human adults had this translocation in the mononuclear fraction of peripheral blood. However, the range of frequency of these translocations spanned almost three orders of magnitude among translocation-positive individuals. Furthermore, there was a statistically significant increase with age in the percentage of individuals who were translocation positive. Such an age correlation was also seen for the percentage of blood donors with rather high translocation frequencies (> or = 20 per 5 x 10(6) peripheral blood mononuclear cells). However, the blood donor who had by far the highest concentration of this translocation was a healthy 35-year-old male containing approximately 900 apparently monoclonal, translocation-bearing cells per 5 x 10(6) peripheral blood mononuclear cells. Our findings suggest that some individuals who may be at risk for follicular lymphoma might be able to be identified by this PCR assay on peripheral blood. Also, these data may help explain the age dependence of the occurrence of this cancer.

Effect of internal direct and inverted Alu repeat sequences on PCR

We have studied the effect of repeated DNA sequence, especially Alu repeats, on PCR. Alu repeats are sequences that are approximately 300 bp long and interspersed at a very high copy number throughout the human genome. We amplified part of the human low-density lipoprotein receptor gene containing two Alu repeat sequences in the same orientation, approximately 7.8 kb apart, with unique sequence primers outside these repeats. The major PCR product was a DNA fragment with an in vitro deletion between the Alu repeats. The formation of this product depended on the template concentration and the type of polymerase used. Such a product arose apparently as a result of a "jumping reaction" involving a primer whose extension was terminated prematurely within one Alu repeated followed by annealing of such an incompletely extended primer to the other, distant Alu repeat. No such jumping products were seen when a 0.8-kb region containing two nearby inverted Alu repeats within the human alpha-galactosidase A gene was subject to PCR with unique sequence primers annealing just outside these repeats.

Observation of therapeutic effect in 50 cases of chronic renal failure treated with rhubarb and adjuvant drugs

Treatment of chronic renal failure with rhubarb and adjuvant drugs combined with other appropriate measures alleviates the suffering of the patients and improves the quality of their survival. Most patients can take care of themselves after treatment, and some can engage in half-day work. The treatment prolongs the life of the patient, and reduces medical expenses. It is of definite social and economic benefit, and conforms with China's conditions. Except for very severe cases whose blood creatinine exceeds 884 mumol/L, it can be given to all patients. It can also be used as a transitional measure before more radical therapies may be instituted.

Seasonal Variations in Rubber Biosynthesis, 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase, and Rubber Transferase Activities in Parthenium argentatum in the Chihuahuan Desert

The rubber content and the activities of enzymes in the polyisoprenoid pathway in Parthenium argentatum (guayule) were examined throughout the growing season in field plots in the Chihuahuan Desert. The rubber content of the plants was low in July and August and slowly increased until October. From October to December there was a rapid increase in rubber formation (per plant) from 589.0 mg to 4438.0 mg. The percentage of rubber in the plants increased from 0.7% (mg/g dry weight) in August and 1.27% in October to 5.5% in December. The rapid increase in rubber formation may result from exposing the plants to low temperatures of 5 to 7[deg]C. The activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) was 21.1 nmol mevalonic acid (MVA) h-1 g-1 fresh weight in the bark of the lower stems in June during seedling growth and decreased to 5.1 nmol MVA h-1g-1 fresh weight in July and 2.9 nmol MVA h-1 g-1 fresh weight in September. From October to December, the activity increased from 5.0 to 29.9 nmol MVA h-1 g-1 fresh weight. The activity of rubber transferase was 65.5 nmol isopentenyl pyrophosphate (IPP) h-1 g-1fresh weight in the bark in September and increased to 357.5 nmol IPP h-1 g-1 fresh weight in December. The rapid increase in the activities of HMGR and rubber transferase coincided with the rapid increase in rubber formation. The activities of MVA kinase and IPP isomerase did not significantly increase in the fall and winter. A tomato HMGR-1 cDNA probe containing a highly conserved C-terminal region of HMGR genes hybridized at low stringency with several bands on blots of HindIII-digested genomic DNA from guayule. In northern blots with the HMGR-1 cDNA probe at low stringency, HMGR mRNA was high in June and November, corresponding to periods of high HMGR activity during seedling growth and rapid increase in rubber formation. The seasonal variations in rubber formation and HMGR mRNA, HMGR activity, and rubber transferase activity may be due to low temperature stimulation in the fall and winter months.

Theory of elliptical defocusing in anisotropic nonlinear-optical media

We have determined the far-field beam profiles of an initially Gaussian laser beam that traverses a thin slab of nonlinear-optical material in which the spatial distribution of the refractive nonlinearity is anisotropic by an expansion in terms of elliptical Gaussian functions. In marked contrast to the annular structures observed with isotropic media, it is shown that the transmitted beam breaks into two beams in the far field. This nonlinear beam-splitting behavior has been confirmed experimentally.