Extracellular labeling of nascent polypeptides traversing the membrane of Escherichia coli

To provide direct evidence for the hypothesis that secreted proteins may traverse membranes as growing chains, we labeled spheroplasts of Escherichia coli with a reagent (acetyl[35S]methionyl methylphosphate sulfone) that reacts with amino groups but does not cross the membrane. After fractionation, about 6% of the label in the membrane-polysome fraction was found to be attached to the polysomes. This attachment was via peptidyl-tRNA, as shown by several tests: release of most of the label from purified polysomes at low Mg2+; subsequent loss of about 25,000 daltons on cleavage by dilute alkali; release by puromycin; and release, accompanied by a marked increase in average molecular weight, on peptide chain completion. Moreover, a significant fraction of the completed chains was identified serologically and by molecular weight as a major periplasmic protein, alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1]. This work provides direct evidence that: (i) secreted proteins thread through the membrane as growing peptide chains; and (ii) membrane-associated polysomes in bacteria are functionally attached to membrane and not merely trapped on disruption of the cell.

Role of the 30S ribosomal subunit, initiation factors, and specific ion concentration in barotolerant protein synthesis in Pseudomonas bathycetes

Washed (1 M NH4Cl) ribosomes from Pseudomonas bathycetes, Pseudomonas fluorescens, and Escherichia coli were tested for their ability to synthesize protein or polypeptide at high pressure when used as such, when recombined with homologous initiation factors, and when recombined with heterologous initiation factors. The responses of natural messenger ribonucleic acid (MS-2)-directed systems to pressure were independent of the source of initiation factors and paralleled those of the washed ribosomes in polyuridylate-directed systems. In all cases, the responses to pressure were parallel to those obtained when unwashed ribosomes were utilized; therefore, we concluded that the initiation factors were interchangeable among these organisms, and that these factors did not play a critical role in determining the pressure responses of the protein-synthesizing systems. P. bathycetes ribosomal subunits were isolated under a variety of ionic conditions. These were tested for their ability to synthesize protein and polyphenylalanine at a variety of pressures when used in reconstituted P. bathycetes homologous systems and in hybrid systems with ribosomal subunits from E. coli and P. fluorescens. O. bathycetes 30S subunits, isolated in a buffer solution containing 0 mM NaCl and O mM KC] were functional at any pressure; those isolated in the presence of 150 mM NaCl and 0 mM KCl were functional at 1 atmosphere but barosensitive, and those isolated in the presence of O mM NaCl and 150 mM KCl retained the ion-mediated barotolerance characteristic of crude P. bathycetes ribosome preparations. The 50S subunit remained functional regardless of the method of isolation, and it had no effect on pressure sensitivity.

Protein synthesis at 680 atm: is it related to environmental origin, physiological type, or taxonomic group?

The ability of bacteria to synthesize protein at 680-atm pressure is not related to their environmental origin, physiological type, or taxonomic group.

Specific ion concentration as a factor in barotolerant protein synthesis in bacteria

The degree of barotolerance exhibited by Pseudomonas fluorescens and Pseudomonas bathycetes in vitro polyphenylalanine-synthesizing systems can be modified by altering the concentrations of specific ions in the reaction mixture. Hybrid-protein-synthesizing systems, utilizing all the possible S-100 supernatant fluid and ribosome combinations from Escherichia coli, P. fluorescens, and P. bathycetes, were tested for barotolerance under conditions of low (16 mM Mg2+ plus 0 mM Na+) and high (150 mM Na+ plus 60 mM Mg2+) ion concentrations. The results reveal that barotolerant synthesis is a characteristic determined by the origin of the ribosome. Systems utilizing E. coli ribosomes are barosensitive at both low and high ion concentrations, P. fluorescens ribosomes barotolerant under both conditions, and P. bathycetes ribosomes barosensitive at low and barotolerant at high ion concentrations. Therefore, certain concentrations of specific ions will increase barotolerance, but only if the ribosomes are capable of functioning at high pressures.

Listeriosis

Four patients with Listeria monocytogenes infection are presented; three of whom had associated lymphoproliferative disorders. Two of the four patients had Listeria meningitis. Meningitis is the most common manifestation of listeriosis in humans. Specific diagnosis depends on demonstrating Listeria monocytogenes in the cerebral spinal fluid; differentiation from other forms of acute meningitis cannot be made clinically. Although listeriosis is recognized as a major global problem in both human and animal health, the epidemiology of human infection is poorly understood. Animals and animal products may serve as reservoirs for human infection. Antibiotic therapy resulted in recovery in three of the patients. The history, epidemiology, laboratory diagnosis, clinical manifestations, and therapy of listeriosis are reviewed.

A rotavirus in lambs with diarrhoea

A reovirus-like agent was identified from an outbreak of enteritis in young lambs. From its morphology and immunological relationship with calf rotavirus, it was concluded that it was a rotavirus which infects lambs.

Fat embolism associated with an atrial septal defect

A case of a patient with pulmonary fat embolism following fractures of femurs and pelvis, with a fatal outcome after 3 days, is presented. Post mortem examination revealed a congenital osteum secundum heart defect, and widespread capillary occlusions from systemic fat microembolization.

Hepatic artery traumatic aneurysm

The diagnosis of intrahepatic aneurysm was suspected following radioisotope scintigraphic studies. A patient developed abdominal pain following blunt abdominal trauma. The scintigrams of the liver revealed a large intrahepatic defect and separation between lung and liver. Angiogram revealed a large false aneurysm of the right hepatic artery.

Role of bacterial ribosome subunits in barotolerance

The barotolerant nature of protein synthesis in Pseudomonas fluorescens is shown to be associated with the 30S ribosomal subunit.

Appearance of C-type virus-like particles after co-cultivation of a human tumor-cell line with rat (XC) cells

A serially progagated cell line (L104) was established by co-cultivation of alung adenocarcinoma (L-1) from a patient with concurrent chronic lymphocytic leukemia and XC, a non-producer rat line, known to carry the Rous sarcoma virus (RSV) genome. Karyotype of the L104 cultures revealed predominantly rat-like patterns; however, about 5% of the cells reacted with HLA antibodies and demonstrated human isozyme patterns. Electron microscopy of L104 cells revealed the presence of C-type particles budding from the cell membranes and in cytoplasmic vacuoles. Virus was not detected in any of the other normal lung, lung tumor or XC cells examined after co-cultivation with XC cells. The particles isolated from tissue culture fluids had the biochemical and biophysical characteristics common to other known mammalian C-type particles and were serologically related to the woolly monkey virus (WMV)/gibbon ape leukemia virus (GaLV) complex. Cross-hybridization between viral 3H-DNA transcripts and cellular RNAs from virus-infected cells clearly show the presence of sequences in the L104 cellular RNA related to both the GaLV/WMV group of viruses and rat viruses. Hydroxyapatite chromatography reveals however that the primate-related sequences in the viral RNA are indistinguishable from WMV in thermal elution profile. The host range of L104 virus appears to vary greatly from WMV in being xenotropic and, in the cell lines thus far tested appears, to infect only rat cells. The virus gave positive KC but negative XC assays. Inoculation of whole cells or cell-free supernatants into weaning hamster did not result in either solid tumors or leukemia. Co-cultivation of appropriate cell lines may represent an approach to the detection of latent viruses in human neoplasia.

Role of bacterial ribosomes in barotolerance

The effects of high hydrostatic pressures on protein synthesis by whole cells and cell free preparations of Escherichia coli, Pseudomonas fluorescens, and Pseudomonas bathycetes were determined. Actively growing cells of P. bathycetes and P. fluorescens were less sensitive than were E. coli cells. Protein synthesis by cell free preparations of E. coli and P. fluorescens showed the same extent of inhibition as their respective whole cell preparations, whereas cell free preparations of P. bathycetes showed a marked increase in pressure sensitivity over whole cells. Protein synthesis by hybrid protein synthesizing cell free preparations (the ribosomes from one organism and the S-100 supernatant fraction from another) demonstrated that response to high pressure is dependent on the source of the ribosome employed. A hybrid system containing E. coli ribosomes and P. fluorescens S-100 shows the same sensitivity to pressure as a homologous E. coli system, whereas a hybrid containing P. fluorescens ribosomes and E. coli S-100 shows the greater pressure tolerance characteristic of the P. fluorescens homologous system.

Cytology of rheumatoid synovial cells in culture. I. Composition and sequence of cell populations in cultures of rheumatoid synovial fluid

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