Isolation of an aggregation inhibitory factor from non-adhesive mouse teratoma cells

An aggregation inhibitory factor (AIF) has been extracted from mouse ascites teratoma cells (that do not aggregate in culture) that retards adhesion of cultured teratoma cells of the same cell line (that do aggregate). Preliminary characterization of AIF on polyacrylamide gels suggests that AIF is a protein composed of four subunits. Extraction of AIF from ascites teratoma cells was accomplished without significant loss of viability by a technique involving the application of an electric field to large numbers of whole cells suspended in a hypertonic electrode buffer. In tests of adhesion, AIF consistently and immediately inhibited aggregation of cultured teratoma cells after 5, 10, 15, and 30 min of incubation. Furthermore, a reduced concentration of AIF resulted in a corresponding decrease in inhibition, suggesting a concentration-dependent action. AIF may help explain how cultured teratoma cells adhere, whereas ascites teratoma cells of the same subline do not adhere.     

The photoreaction center of Rhodospirillum rubrum mutant strain F24.1

Rhodospirillum rubrum strain F24.1 is a spontaneous revertant of nonphototrophic mutant F24 derived from wild-type strain S1. Strain F24 shows no detectable photochemical activity and contains, at most, traces of the photoreaction center polypeptides. Strain F24.1 has a phototrophic growth rate close to that of the wild-type strain (Picorel, R., del Valle-Tascón, S. and Ramírez, J.M. (1977) Arch. Biophys. Biochem. 181, 665–670) but shows little photochemical activity. Light-induced absorbance changes in the near-infrared, photoinduced EPR signals and ferricyanide-elicited absorbance changes indicate that strain F24.1 has a photoreaction center content of 7–8% as compared to strain S1. Polyacrylamide gel electrophoresis of isolated F24.1 chromatophores shows the photoreaction center polypeptides to be present in amounts compatible with this value. Photoreaction center was prepared from strain F24.1 and showed no detectable difference with that of strain S1. It is concluded that strain F24.1 photosynthesis is due entirely to its residual 7–8% of typical photoreaction center.     

Use of an IgG fragment prepared with particulate plasmin to study the C1 binding and activation.

Facb, fragment antigen and complement binding (this last property is shown when the fragment is involved in an immune complex); Fc, C-terminal half of the heavy-chain dimer; pFc′, major C-terminal fragment released from IgG by pepsin or plasmin digestion; DFP, diisopropylphosphofluoridate; ATEE, N-acetyl-L-tyrosine ethyl ester; BAEE, N-benzoyl-L-arginine ethyl ester; TAME, p-toluene sulfonyl-L-arginine methyl ester; SDS, sodium dodecyl sulfate; SBTI, soybean trypsin inhibitor.The nomenclature of the complement components (C1, C1q, C1r, C1s) follows the W.H.O. recommendations. Enzymatic activities are expressed in nanokatals (nkat.) as recommended in the Enzyme Nomenclature (1973).     

Attenuation by catecholamine antagonists of the hypothermia that follows cerebral infarction in gerbils.

The hypothermia that follows induction of cerebral infraction in gerbils can be attenuated by drugs which reduce the interactions between endogenous brain catecholamines and postsynaptic receptors. This observation is compatible with the hypothesis that stroke-induced hypothermia is mediated, in part, by the release of catecholamines from ischemic neurons.     

Enhanced Dissolution of Oil Shale by Bioleaching with Thiobacilli

Oil shale was subjected to bioleaching by cultures of thiobacilli. From X-ray, electron microprobe, and thin-section petrographic analysis, the shale matrix was found to contain tightly bonded carbonate minerals. When subjected to the bioproduced acids, these carbonate minerals were removed successively from the shale matrix. This process created pits and cavities which were gradually enlarged as indicated by scanning electron micrographs of samples subjected to leaching for varying lengths of time. At the end of 14 days, essentially all available carbonates had been depleted from the solid matrix. The effected increase in porosity and permeability of the oil shale then enhanced the exposure of fuel precursors, thus facilitating their production and conversion.     

Electron transfer proteins of the purple phototrophic bacterium, Rhodopseudomonas rutila.

The soluble electron transfer protein content of Rhodopseudomonas rutila was found to consist of two basic cytochromes and a (4Fe-4S) ferredoxin. Cytochrome c' was easily identified by its characteristic high spin absorption spectra. The native molecular weight is 29,000 and the subunit is 14,000. Cytochrome c-550 has low spin absorption spectra and a high redox potential (376 mV) typical of cytochromes c2. The molecular weight is about 14,000. The ferredoxin is apparently a dimer (43,000) of approximately 18,000 Da subunits. There are 1.3 to 1.5 iron-sulfur clusters per monomer of 18- to 21-kDa protein. The N-terminal amino acid sequence is like the (7Fe-8S) ferredoxins of Rhodobacter capsulatus and Azotobacter vinelandii. Remarkably, there are only 2 or 3 out of 25 amino acid substitutions. Difference absorption spectra of Rps. rutila membranes indicate that there is not tetraheme reaction center cytochrome c, such as is characteristic of Rps. viridis. However, there are a high potential cytochrome c and a low potential cytochrome b in the membrane, which are suggestive of a cytochrome bc1 complex. Rps. rutila is most similar to Rps. palustris in microbiological properties, yet it does not have the cytochromes c-556, c-554, and c-551 in addition to c2 and c', which are characteristic of Rps. palustris. Furthermore, the Rps. rutila cytochrome c' is dimeric, whereas the same protein from Rps. palustris is the only one known to be monomeric. The cytochrome pattern is more like that of Rhodospirillum rubrum and Rb. capsulatus, which are apparently only able to make cytochromes c2 and c'.