Complexation of copper(II) by a peptide hybrid of bleomycin and amsacrine. Circular dichroism and electron spin resonance studies

A model incorporating the metal chelating moiety of bleomycin and an anilinoacridine ring able to intercalate in DNA has been synthesized. The copper(II) complex of that molecule has been studied using circular dichroism and electron spin resonance by comparison with bleomycin. The introduction of the anilinoacridine ring involves a modification in the geometry of the complex. A distortion of the square-pyramidal form (type II complex) gives rise to a type I complex in which the metallic atom is drawn out of the plane of the four square-planar ligands and displaced slightly towards the fifth ligand.     

c-myc oncogene expression inhibits the initiation of myogenic differentiation

The role of c-myc oncogene expression in myogenic differentiation has been established by transfecting rat myoblasts of the L6 cell line with plasmid pMT-myc, in which the c-myc coding sequences were under the control of the metallothionein I promoter. We observed that the constitutive expression of the exogenous c-myc gene inhibits muscular differentiation. A diminution of the endogenous c-myc gene expression occurs within the first 24 h after the transfer of the cells to a differentiating medium. This early decrease of c-myc expression is required for cell differentiation to occur. We have also observed that exogenous myc gene expression has no effect on endogenous myc expression.     

Propionicacidemia: absence of alpha-chain mRNA in fibroblasts from patients of the pccA complementation group.

Propionicacidemia is an autosomal recessive metabolic disease resulting from a deficiency of propionyl-CoA carboxylase (PCC) activity. The enzyme has the structure alpha 4 beta 4, with the alpha chain containing a covalently bound biotin prosthetic group. Patients have been placed into two major complementation groups, pccA and pccBC, that may correspond to the genes encoding the alpha and beta chains of PCC. The pccBC group is further divided into two subgroups, pccB and pccC, apparently owing to intragenic complementation. We previously reported combined alpha- and beta-chain deficiency in pccA mutants and absence of beta chain in pccC and pccBC mutants after isotope-tracer labeling and immunoprecipitation of cultured-fibroblast extracts. Using cDNA clones coding for the alpha and beta chains as probes, we found absence of alpha mRNA in four of six pccA strains and presence of beta mRNA in all pccA mutants studied. We also found presence of both alpha and beta mRNAs in three pccBC, two pccB, and three pccC mutants. From these data, we confirm the gene assignments of the complementation groups (PCCA gene = pccA complementation group; PCCB gene = pccBC and subgroups) and support the view that pccA patients synthesize a normal beta chain that is rapidly degraded in the absence of complexing with alpha chains.     

Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions

Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste.     

Cross-linking of streptomycin to the 16S ribosomal RNA of Escherichia coli

[3H]Dihydrostreptomycin was cross-linked to the 30S ribosomal subunit from Escherichia coli with the bifunctional reagent nitrogen mustard. The cross-linking primarily involved the 16S RNA. To localize the site of cross-linking of streptomycin to the 16S RNA, we hybridized RNA labeled with streptomycin to restriction fragments of the 16S RNA gene. Labeled RNA hybridized to DNA fragments corresponding to bases 892-917 and bases 1394-1415. These two segments of the ribosomal RNA must be juxtaposed in the ribosome, since there is a single binding site for streptomycin. This region has been implicated both in the decoding site and in the binding of initiation factor IF-3, indicating its functional importance.