Leukocyte-transforming agents were isolated in baboon leukocytes inoculated with oral excretions from immunosuppressed chimpanzees. The transformed lymphoblasts had B cell surface markers and harbored herpes-type virus particles; 5-10% of the cells contained cytoplasmic antigens reactive with Epstein-Barr virus (EBV)-antibody-positive chimpanzee, human and baboon sera. These sera also neutralized the transforming activity of the chimpanzee virus. Long-term lymphoid cell lines were established from circulating lymphocytes of normal baboons: two from Papio cynocephalus and three from P. hamadryas. The cells had B cell surface markers, contained herpes-type virus particles and produced virus with leukocyte-transforming activity. No virus-associated nuclear antigen was detectable with reference baboon and chimpanzee sera; however, the cells reacted with selected human sera containing antibodies to EBV nuclear antigen (EBNA). Absorption experiments confirmed the specificity of this reaction. Baboon lymphoblasts produced baboon virus-associated soluble complement-fixing (CF/S) antigen. Baboon sera had CF antibodies to viral (CF/V) antigen derived from EBV but failed to react with EBV-associated CF/S antigen. Chimpanzee and baboon herpesviruses had similar in vitro host cell ranges but were different from those of EBV. Inoculation of baboons, rhesus monkeys and cottontop marmosets failed to produce detectable illness or palpable tumors.

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IntroductionAs a part of a study of organ and cellular senescence in plants, wve are delineating the structural and functional changes which occur in the cotyledons of germinating peas. As might have been expected from earlier reports that cotyledon cells are capable of performing oxidative phosphorylation, incorporation of labeled amino acids into protein (4) and de novo synthesis of certain enzymes (5), examination by electron microscopy showed the presence of all structures normally present in plant cells. In addition, a major fraction of the cell volume was found to be occupied with relatively large roughly spherical bodies, with no visible internal structure. The data presented here indicate that the reserve globulins are localized in these structures. These structures are easily isolated as a pellet following centrifugation of a pea cotyledon homogenate. The presence of similar protein bodies in peanut cotyledons has already been reported (1, 3). Material & MethodsThe peas (Pisunt sativurn, var. Early Alaska) were soaked in 1 % sodium hypochlorite for 30 minutes, rinsed in sterile distilled water, and transferred to moist sand in sterile Petri dishes. After one to three days' incubation at 25 C. the cotyledons were excised and examined microscopically and chemically. For Figure 5, 6, and 7 show the results of the chromatography of the various fractions OI1 DEAE colunmns and further support the conclusion that tile iiain component of the pellet and the proteiin bodlies is the globulin fraction and that the globulin fractioll is the major protein fraction of the pea cotyledon cells. It is interesting to note that the chromiiatograpllic separationl suggests the presence of four comiiponents in the globulin fraction while ultracentrifugal analyses indicate tw o major components (2).The supernatant fraction chromatographe(l in figure 8 -as from cotyledons of 3-daV old germlinating peas. The first pyrophosphatase peak may be an artifact. The three nmajor peaks always appear during cliromiiatography and the last pyrophosp)llatase peak increases greatly (luring tile third to sixtlh lays of germination. The sniall adenosine triphosphatase peak results froill the low activity of tile corresponding pyrophosphatase peak toward ATI at pH 7.1. The major adenosine triphosphatase peatk increases greatly duriing germiiiatioll an(l is the einzvnme stu(lied earlier by Young ail(l Varner (5). Tile proteins which becomle labeled in vivo fr-omii C14-labeled amiinio aci(ds (4) are in tile albulliin fraction and separate into five or six (liscrete peaks under the chromatographic con(litiolns use( hlere. B' a COIllbinlation of ill Xvixo iiltro(luctioil of lalbeledl aniiiio acids into proteills and the separation of these proteills by column cllromatographyv we liope to be able to identifv those enzymes which increase ill activity as a result of (le ilovo syntiesis and those whici illcrease as a result of solle kinld of activation. SummaryElectronmllicrograplis of pea cotyledon cells show that roughly-spherical bodies of about t...

Electron Microscopy. Tissues and cell pellets were fixed in 2.5% glutaraldehyde, rinsed with several changes of 0.01 M phosphate-buffered saline, treated with Dalton's chromeosmium, and rinsed again with several changes of distilled, deionized water (6). The specimens were stained overnight with 1% uranyl-acetate in 50% ethanol, dehydrated with increasing concentrations of ethanol, followed by propylene oxide, and embedded in Luft Epon. Thin sections were stained with lead citrate. Negative stains were prepared by mixing isopycnically banded virus in 0.05 M sodium citrate (pH 6.0) with 2% potassium phosphotungstate (pH 4.0). The mixture was deposited on a carbon-coated grid, drained, and air-dried just prior to use. Viral Polymerase Assays. Virus from culture supernatants was concentrated and assayed for viral reverse transcriptase as described (2, 3). Reactions were carried out in a total volume of 0.1 ml using 0.5 Ml of virus (10 Mig of protein) and contained 50 mM Tris-HCI (pH 7.8), 4 mM dithiothreitol, 60 mM KCI, 0.03% Triton X-100, and MnCl2 or MgCl2 as indicated. Po-

We have studied the virus produced by a clone, termed 8A, that was isolated from a culture of murine sarcoma virus-transformed mouse cells after superinfection with Moloney murine leukemia virus (MuLV-M). Clone 8A produced high levels of type C virus particles, but only a low titer of infectious murine sarcoma virus and almost no infectious MuLV. When fresh cultures of mouse cells were infected with undiluted clone 8A culture fluids, they released no detectable progeny virus for several weeks after infection. Fully infectious MuLV was then produced in these cultures. This virus was indistinguishable from MuLV-M by nucleic acid hybridization tests and in its insensitivity to Fv-1 restriction. It also induced thymic lymphomas in BALB/c mice. To explain these results, we propose that clone 8A is infected with a replication-defective variant of MuLV-M. Particles produced by clone 8A, containing this defective genome, can establish an infection in fresh cells but cannot produce progeny virus at detectable levels. Several weeks after infection, the defect in the viral genome is corrected by back-mutation or by recombination with endogenous viral genomes, resulting in the formation of fully infectious progeny MuLV. The progeny MuLV's that arose in two different experiments were found to be genetically different from each other. This is consistent with the hypothesis that, in each experiment, the progeny virus is formed as a result of an independent genetic event. DNA was isolated from clone 8A cells and assayed for infectivity by the calcium phosphate transfection technique. No detectable MuLV was produced by cells treated with this DNA. This finding, along with positive results obtained in control experiments, indicates that clone 8A cells do not contain a normal MuLV provirus.