Characterization of two solitary long terminal repeats of murine leukemia virus type that are conserved in the chromosome of laboratory inbred mouse strains.

Twenty molecular clones containing sequences homologous to the long terminal repeats (LTRs) of the endogenous ecotropic murine leukemia virus (MuLV) of the RFM/Un mouse were isolated from a library of RFM/Un mouse spleen DNA in phage lambda. Three of these LTRs were not associated with any viral structural genes. Nucleotide sequence analysis demonstrated that they were solitary LTRs which were flanked by 4-bp directly repeated cellular sequences and which lacked primer binding sites.

Cadmium resistance in Drosophila: a small cadmium binding substance.

A small cadmium-binding substance (CdBS) has been observed in adult Drosophila melanogaster that were raised for their entire growth cycle on a diet that contained 0.15 mM CdCl2. Induction of CdBS was observed in strains that differed widely in their sensitivity to CdCl2.

Distance between two active-site lysines of ribulose bisphosphate carboxylase from Rhodospirillum rubrum.

In the absence of a three-dimensional structure of ribulose-bisphosphate carboxylase/oxygenase [3-phospho-D-glycerate carboxy-lyase(dimerizing), EC 4.1.1.

X-ray structure of the nucleosome core particle.

Two monoclinic crystal forms (P2(1),C2) of chicken erythrocyte nucleosomes have been under study in this laboratory. The x-ray structure of the P2(1) crystal form has been solved to 15 A resolution. The B-DNA superhelix has a relatively uniform curvature, with only several local distortions observed in the superhelix.

Prostaglandin modulation of phorbol ester skin tumor promotion.

TPA promotion of skin tumors in mice can be modified by application of various prostaglandins or their precursors. The effects depend on the particular prostaglandin used: PGF2alpha enhances promotion, whereas PGE1 consistently inhibits promotion. Time of application of the prostaglandin with respect to TPA determines whether PGE2 enhances or inhibits.

Metabolism of carcinogenic 2-hydroxybenz.

The rates of metabolism of the carcinogenic 2-hydroxybenzo[a]pyrene (2-OH-B[a]P) and the non-carcinogenic 3- and 9-hydroxybenzo[a]pyrenes in cultured cell systems have been studied and compared. While 70-80% of the non-carcinogens are converted to water-soluble derivatives by hamster embryo fibroblasts in 24 h, carcinogenic 2-OH-B[a]P is metabolized at a slower rate (45% in 24 h), comparable to that for the parent hydrocarbon, benzo[a]pyrene (B[a]P). Analysis of extracellular organic solvent-soluble metabolites of 2-OH-B[a]P in cultured hamster embryo fibroblasts, using h.

Rapid release of protease inhibitors from soybeans: immunochemical quantitation and parallels with lectins.

Specific antisera were prepared against the Bowman-Birk trypsin inhibitor and four other trypsin inhibitors of low molecular weight isolated from soybeans (Glycine max L. cv. Tracy).

Osmotic shrinkage as a factor in freezing injury in plant tissue cultures.

Haplopappus gracilis and Acer saccharum tissue culture cells are extremely sensitive to freezing injury, and exhibit a decrease in survival from 98% at -1 C to 4% at -3 C (Haplopappus) and 92% at -3 C to 13% at -5 C (Acer) when suspended in distilled H(2)O, seeded at -1 C, and then cooled by 0.1 C/minute. Similar results are obtained when cells are suspended in growth medium.

Light-stimulated Production of a Chloroplast-localized System for Protein Synthesis in Euglena gracilis.

Chloroplasts and proplastids isolated respectively from autotrophic and dark-adapted cells of Euglena gracilis strain Z incorporated (14)C-l-leucine into protein. In each case the incorporation was inhibited by chloramphenicol (50% inhibition at about 5 mug/ml for chloroplasts and 30 mug/ml for proplastids), but not appreciably by cycloheximide at concentrations up to 200 mug/ml. Chloroplasts from autotrophic cells incorporated leucine into protein at rates of about 10 pg leucine per mg RNA in one minute, but isolated proplastids were only 5 to 10% as active.

Protein synthesis by isolated etioplasts and chloroplasts from pea and wheat and the effects of chloramphenicol and cycloheximide.

Etioplasts capable of incorporating (14)C-leucine into protein have been isolated from dark-grown pea and wheat plants. The requirements for leucine incorporation for etioplasts were similar to those for chloroplasts. An ATP-generating system, Mg(2+), and GTP were required.