Normal fibroblast mitochondrial malic enzyme activity in Friedreich's ataxia.

Mitochondrial and cytoplasmic malic isoenzymes were assayed fluorometrically in digitonin-fractionated fibroblasts from three patients with Friedreich's ataxia (FA). Normal activity was found, failing to verify an earlier report of reduced fibroblast mitochondrial malic enzyme activity in FA. The previously reported disturbance in fibroblast mitochondrial malic enzyme may be an epiphenomenon in patients with the FA phenotype. Further studies are necessary to define the primary genetic defect in this inherited disorder.

Co-localization of cyclic GMP in superior cervical ganglion with peptide neurotransmitters.

The immunofluorescent localization of cyclic 3',5'-guanosine monophosphate (cyclic GMP) in rat superior cervical ganglion has been compared to postganglionic neurons having immunoreactivity to neuropeptides. Cyclic GMP-positive somata are equally distributed among cell bodies fluorescent for substance P, somatostatin, and methionine-enkephalin. 40% of the total number of cells stained for each peptide demonstrate co-incident cyclic GMP localization, suggesting a large majority of the neurons employ non-cyclic GMP mechanisms.

Isolation of a ribonucleoprotein structure from oncornaviruses.

Detergent treatment releases from both avian and mammalian oncornaviruses a structure containing the viral RNA and a major arginine-rich protein, as well as reverse transcriptase activity.

Chromatographic and electrophoretic analysis of viral proteins from hamster and chicken cells transformed by Rous sarcoma virus.

Several methods have been explored for the detection and characterization of viral proteins from soluble extracts of cells transformed by Rous sarcoma virus (RSV). Viral antigens have been analyzed after gel filtration in several solvents. In addition, immune complexes formed with virus-specific sera have been isolated by agarose gel filtration and by high- or low-speed centrifugation through sucrose solutions. Radioactive proteins from these immune complexes have been analyzed by gel filtration in 6 m guanidine hydrochloride or by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Comparison with proteins from purified virus indicates the presence of two viral core proteins (gs1 and gs2) in the soluble fraction from virus-producing chicken cells. In the same fraction from RSV-transformed hamster cells (which do not produce virus), three gs proteins (gs1, gs2, and gs3) could be identified. The soluble viral gs proteins are strongly bound to at least two larger polypeptides in cell extracts. These polypeptides do not appear to be viral in origin and have the property of undergoing a time-dependent aggregation in the extracts. One of these cell-derived proteins, which is present in a variety of uninfected cell types, closely resembles actin.

Chromatographic separation and antigenic analysis of proteins of the oncornaviruses. V. Identification of a new murine viral protein, p15(E).

Profiling of murine leukemia virus (MuLV) proteins by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) has revealed a low-molecular-weight protein which does not appear in the corresponding region of viral protein profiles obtained by gel filtration in 6 M guanidine hydrochloride. This protein species, termed p15(E), is easily demonstrable in MuLV isolates for which the viral p15 and p12 proteins have almost identical electrophoretic mobilities; this leaves a protein slightly larger than these two in the PAGE system unaccounted for in the gel filtration system. However, antiserum against the void volume fraction of the gel filtration eluate precipitated the p15(E) component from solubilized, radiolabeled virions, as shown by SDS-PAGE analysis of such immunoprecipitates. Comparative radioprecipitation analyses of this type revealed that for various MuLV isolates p15(E) was distinguishable from p15 in terms of serological reactivities, relative mobilities in gel electrophoresis, and relative efficiencies of labeling with individual amino acids. Thus it appears that, as is the case for avian oncornaviruses, MuLVs contain seven major structural proteins.

Polymorphism of B-tropic leukemia viruses from BALB/c mice: association of a p30 antigen with N- versus B-tropism.

Comparison of a number of murine leukemia virus clones by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed extensive protein polymorphism among B-tropic, but not N-tropic, isolates from BALB/c mice, particularly in migration of p30 proteins. A type-specific radioimmunoassay for p30 was developed which uniformly discriminated all B-tropic viruses from N-tropic viruses of BALB/c origin. N- and B-tropic viruses of C57BL/6 and AKR Fv-1b/b origin could also be distinguished by this assay.