Chromosome transfer and R-prime formation by an RP4::mini-Mu derivative in Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, and Proteus mirabilis

We have introduced into the wide host range conjugative plasmid RP4, a mini-Mu derivative which was known to be able to transpose spontaneously in E. coli K-12, and to induce in such a host several kinds of chromosomal rearrangements including replicon fusions. Unlike RP4, RP4::mini-Mu can mediate the transfer of the host chromosome to a recipient bacterium and generate R primes at high frequencies (10^?4 for the transfer of a given marker, 10^?5 for the formation of R primes carrying a given marker). Two such RP4::mini-Mu plasmids were introduced into one Salmonella typhimurium strain, one Klebsiella pneumoniae strain, and one Proteus mirabilis strain. Each of these three strains were mated with an E. coli K-12 recipient and transconjugants carrying R primes were recovered in all three cases at frequencies ranging from 5 × 10^?6 to 10^?7.     

Compartmentation of high-energy phosphates in resting and beating heart cells

The subcellular distribution of ATP, ADP, creatine phosphate and creatine has been analyzed by fast detergent fractionation of isolated frog heart cells. Digitonin fractionation (0.5 mg/ml, 10 s at 2 degrees C in 20 mM 4-morpholinepropanesulfonic acid/3 mM EDTA/230 mM mannitol medium) was used to separate mitochondria and myofilaments from cytosol. To separate myofilaments from the other cellular compartments. Triton X-100 was used (2%, 15 s in the same medium as digitonin). For either resting or beating cells the total cellular contents of ATP, ADP, creatine phosphate and creatine was similar, nevertheless the O2 consumption was 6-times higher. The compartmentation of these metabolites was also identical. Myofilaments contain 1.1 nmol ADP per mg total cellular proteins. In the cytosolic compartment the metabolite concentrations, all measured in nmol per mg total cellular proteins, were: ATP, 13; ADP, 0.25-0.05; creatine phosphate, 18.5 and creatine, 14. This indicated that the reaction catalyzed by creatine kinase was in a state of (or near) equilibrium.     

Use of a radioimmunoassay technique to measure the titer of anti-cow-zona antibodies in marmoset monkeys

A double antibody radioimmunoassay technique is described for the measurement of anti-zona antibodies in the peripheral plasma of marmosets actively immunized against intact cow zonae pellucidae. The method has been shown to be a reliable, repeatable indicator of antibody titer, enabling direct comparison of the response obtained between marmosets. This is the first report of a procedure describing the active immunization of a primate against zona antigens, and the first time a radioimmunoassay technique has been used to monitor profiles of anti-cow zona antibody production following active immunization. The method should prove to be a useful tool in the evaluation of zona antigens as agents for immunocontraception.     

In vitro anti-HIV activity of phosphorothioate alpha-anomeric oligodeoxynucleotides

Oligonucleotide analogs consisting exclusively of alpha-anomeric deoxynucleoside units bridged with phosphorothioate linkages have been synthesized and tested in vitro as antiviral agents against human immunodeficiency virus (HIV) in human T cells. Two 28-mers, an homopolymer alpha-S-dC28 and an oligomer alpha-S-anti-rev complementary to the initiation site of the regulatory viral gene rev exhibited antiviral activities comparable to those reported for the corresponding beta-anomeric phosphorothioate analogs. In contrast, a nuclease-resistant homopolymer, alpha-dC28 was inactive. Their preliminary results would indicate that the origin of oligonucleotide phosphorothioate anti-HIV activity is not exclusively correlated with their higher nuclease resistance.     

Neutral microprotein, a novel human plasma and urinary protein associated with a yellow-brown chromophore. Isolation from protein HC preparations and partial characterization

An apparently novel human plasma and urinary protein of low molecular weight was isolated from several highly purified preparations of protein HC by gel chromatography and high voltage electrophoresis with a yield of about 8 mg/g. The protein has a molecular weight of about 20,000, neutral electrophoretic mobility at pH 6.5 and a high content of half-cystine. It is associated with a yellow-brown chromophore like protein HC and could be demonstrated in all investigated preparations of isolated human, rabbit and guinea-pig protein HC and alpha 1-microglobulin.     

Purple pigmentation in leaves of some tropical weed species

The photoacoustic spectroscopic studies of purple pigmented leaves revealed the occurrence of anthocyanins and betalains in some local weed species growing on soils with low moisture levels. The pigmentation intensities were higher in C₄ plants than in C₃ plants. An inverse correlation was observed between pigmentation intensities and soil moisture levels. This work is a part of the UNEP Research Project granted to Prof. D. O. Hall, UNEP Coordinator, Department of Plant Sciences, King’s College; London.