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The v-akt oncogene codes for a 105-kilodalton fusion phosphoprotein containing Gag sequences at its amino terminus. Sequence analysis of v-akt and biochemical characterization of its product revealed that it codes for a protein kinase C-related serine-threonine kinase whose cellular homolog is expressed in most tissues, with the highest amount found in thymus. Although Akt is a serine-threonine kinase, part of its regulatory region is similar to the Src homology-2 domain, a structural motif characteristic of cytoplasmic tyrosine kinases that functions in protein-protein interactions. This suggests that Akt may form a functional link between tyrosine and serine-threonine phosphorylation pathways.

Mycoplasmas are totally inactivated by a 20-min treatment with 1% phenethyl alcohol, whereas suspensions of enveloped viruses resist the same treatment. This treatment has proved successful in eliminating mycoplasma contamination of a virus suspension.

A specific probe for detecting ecotropic murine leukemia virus sequences was constructed by cloning a 500-base-pair DNA segment, corresponding to a portion of the env region of the AKR ecotropic virus, in a pBR322/Escherichia coli K-12 host/vector system. This probe was used to screen the cellular DNAs of six inbred strains of mice for the presence of ecotropic retroviral DNA sequences by the Southern blot hybridization procedure. Three copies of ecotropic viral DNA were detected in AKR/N (a high-ecotropic virus strain) and two were found in BALB/c (a low-ecotropic virus strain) DNAs. As expected, no sequences reactive with this probe were found in NFS mouse DNA (a virus-negative strain). However, cellular DNA sequences that reacted strongly with the ecotropic-specific DNA probe were detected in certain NZB, C57L, and 129 mice (all virus-negative strains). In contrast to the reactive sequences in AKR and BALB/c, the reactions were chiefly associated with EcoRI segments that were subgenomic in size.

The directly transforming murine retrovirus, AKT8, was isolated from a spontaneous AKR thymoma and carries the cell-derived viral oncogene, akt. We have now shown that this virus produces thymic lymphomas after inoculation of susceptible mouse strains. The presence of the AKT8 genome in the DNA of the virus-induced tumors was demonstrated by Southern blotting using an akt-specific probe. These results establish the in vivo pathogenicity of the AKT8 virus and its akt oncogene, and imply a potential role for the cellular akt proto-oncogene in tumor development.

The diagnoses of chronic lymphocytic leukemia (CLL) in prolymphocytic transformation, and diffuse large cell lymphoma (DLC), were made simultaneously in a 71-year-old man. The DLC showed mu lambda surface immunoglobulin. The CLL in a lymph node and in the peripheral blood showed mu kappa. Immunoglobulin gene DNA analysis confirmed the presence of different rearrangements in the heavy and light chain genes of the CLL and DLC. Other cases reported of Richter's syndrome are discussed, and it is concluded that there may be two types of Richter's syndrome, those arising from transformation of a single clone, and those occurring from expansion of two morphologically and immunologically distinct clones, as, it is believed, is the case in this patient.

The human AKT1 gene is the proto-oncogene of the viral oncogene v-akt. The AKT1 gene has been localized to human chromosome 14, band q32, proximal to the heavy-chain immunoglobulin locus (IGHM), by analysis of human-hamster somatic cell hybrids and by in situ hybridization. Chromosome rearrangements of this band which occur in T-lymphoid malignancies and Hodgkin's disease may affect the AKT1 gene.

DNAs isolated from individual mice of four AKR sublines (AKR/J, AKR/N, AKR/Cum, and AKR/Boy) were examined by hybridization of electrophoretically separated restriction enzyme fragments to a 500-base pair, 32P-labeled probe specific for env sequences of ecotropic murine leukemia virus. Variation in the number of proviral DNA copies and in their genomic organization, as reflected by the location of restriction enzyme sites in flanking cellular sequences, was observed both between and within AKR sublines. Evidence is presented for the continual acquisition of new proviruses in the four sublines studied. The ecotropic proviral DNA copies present in the four AKR sublines can be related to their genealogy; each subline contains two or three copies of proviral DNA in common with other sublines and from one to six unique ecotropic proviruses. Overall, a new copy appears about every 12 generations of inbreeding. Some of the unique proviral DNA copies contain internal alterations, as reflected by restriction enzyme maps that differ from those of prototype ecotropic proviruses.

Eight independently derived mouse cytomegalovirus (MCMV) mutants resistant to acyclovir (ACV) were obtained by the sequential plating of wild-type virus in increasing concentrations of ACV. Results of complementation studies among these eight mutants suggest that all had mutations within the same or closely associated genes. A ninth MCMV mutant resistant to phosphonoacetate (PAA) derived by plating wild-type virus in the presence of 100 micrograms of PAA per ml displayed coresistance to ACV and was unable to complement any of the ACV-derived mutants. Recombination experiments among all combinations of the nine MCMV mutants were performed and supported the complementation data in that no recombination could be detected. Seven of the eight ACV-resistant mutants demonstrated cross-resistance to PAA and hypersensitivity to aphidicolin. The one mutant not coresistant to PAA was more susceptible to PAA than was the parent virus. Only a few mutants demonstrated coresistance when the mutants were tested against 9-beta-D-arabinofuranosyladenine (ara-A). The ACV mutant that demonstrated increased susceptibility to PAA was 30-fold more susceptible to ara-A but remained unchanged in susceptibility to aphidicolin. Two of the parent-mutant combinations were selected for DNA synthesis analysis in the presence of ACV (5 microM). A significant decrease in DNA synthesis was demonstrated for both parent viruses, and there was little effect on mutant virus DNA synthesis at the same drug concentration. These results suggest that susceptibility of MCMV to ACV is confined to a product of a single gene and that a mutation of this gene can lead to an altered phenotype when compared with parent virus in susceptibility of DNA synthesis to PAA, ara-A, and aphidicolin, drugs that are known to inhibit DNA polymerase activity.

A total of 151 unselected malignant and nonmalignant lymphoid tissue samples were surveyed by Southern blotting for the presence of Epstein-Barr virus (EBV) DNA. Eight of 28 Hodgkin's disease (HD) samples (29%) had detectable EBV DNA. Both nodular sclerosis and mixed cellularity histologic results were positive. The tumor type with the next highest frequency, 8%, was diffuse large cell lymphoma. The presence of EBV DNA in some HD biopsies suggests that EBV may be a factor in the pathogenesis of this disease. Alternatively, its presence may be secondary to the immune deficiency characteristic of HD. The clonal B-lymphocyte expansions reported in some cases of HD may result from EBV infection.

Murine leukemia viruses capable of malignant transformation of mink tissue culture cells have been isolated from an AKR thymoma cell line and from a spontaneous reticulum cell sarcoma in an NIH Swiss mouse partially congenic for the AKR ecotropic virus-inducing locus Akv-2. In contrast to the recently described mink cell focus-inducing strains of murine leukemia virus, at least one of the two transforming strains is replication defective. Nonproducer mink cells carrying the genome of the transforming virus of AKR origin have been isolated, and pseudotype transforming viruses generated.

A previous report described the isolation of a directly transforming retrovirus, AKT8, from a spontaneous thymoma of an AKR mouse. The AKT8 provirus has now been molecularly cloned from a transformed, nonproducer cell line. The virus genome contains both viral and nonviral, cell-related sequences; the nonviral sequence has been designated v-akt, the presumed viral oncogene of the AKT8 virus. This gene lacks homology to the 16 other oncogenes tested. The cloned provirus has undergone a partial deletion, during cell passage in vitro, that prevents direct demonstration of the transforming ability of this molecular clone. Two human homologues of the v-akt oncogene, AKT1 and AKT2, were cloned. A survey of 225 human tumors for changes involving AKT1 led to the discovery of a 20-fold amplification of this gene in one of the five gastric adenocarcinomas tested. The results demonstrate that AKT8 has the characteristic structure of a directly transforming retrovirus and that it contains a gene derived from highly conserved cellular sequences that may be involved in the pathogenesis of some human malignancies.

Two sublines of HL-60 human promyelocytic leukemia cells were examined cytogenetically with banding techniques. The karyotype of one subline was 44,X,-X,-5,-9,-10,-15,-17,+18,8q+,14q-,16q+,16q+,+mar1,+mar2 ,+mar3. The defective chromosome #8 contained an expanded chromosomal segment at the end of the long arm at band q24. The segment appeared to be a homogeneously staining region on the basis of quinacrine fluorescence banding. Using G-banding technique, this segment showed some evidence of indistinct aberrant bands and, thus, was designated an abnormally banded region (ABR). Double minute chromosomes (DM) were not seen in these cells. The second subline showed a similar karyotype; however, these cells lacked the 8q+ marker and contained one to 37 DM in approximately 90% of the cells examined. Because HL-60 cells are known to contain multiple copies of the c-myc oncogene, in situ chromosomal hybridization of a c-myc probe to HL-60 metaphase cells was performed to localize the amplified genes. The hybridization studies revealed localization to the ABR, as well as to DM, which is consistent with amplification of c-myc within these novel interchangeable chromosomal aberrations.

Six cases of diffuse large cell lymphoma (DLCL) of the liver were studied with immunohistochemistry for common leukocyte antigen (CLA), lysozyme, alpha-1-antitrypsin (AAT), and kappa and lambda light chains on paraffin-embedded tissues. All six cases were positive for CLA. Four of the six cases showed staining for lysozyme and AAT (three focal and one diffuse staining). In three cases, frozen tissue for monoclonal antibodies and glutaraldehyde-fixed tissue for electron microscopic examination were available. Two of these showed B-cell phenotypes with monoclonal antibody studies. Electron microscopic examination on these two B-cell lymphomas showed scant cytoplasm and a paucity of cytoplasmic organelles. The third case did not show definite B- or T-cell surface markers but did show strong Leu-M1 and OKM1 staining. Electron microscopic examination of the tumor cells showed a prominent Golgi apparatus, abundant cytoplasm with numerous cytoplasmic organelles and phagolysosomes. However, DNA hybridization studies on this tumor showed immunoglobulin heavy and kappa light chain gene rearrangements typical of a B-cell lymphoma. All six lymphomas were solitary liver masses without evidence of disease elsewhere. The mean age for the six patients was 56.2 years (four males, two females).

Mutants resistant to dihydrostreptomycin were isolated and genetically analyzed in Bacillus subtilis. Two new classes of mutants distinct from the ribosomal strA locus were found. One class, strB, was located between metC3 and ura-1 on the chromosome. The second class, strC, mapped in the spore gene region close to the spoA locus. Both mutant classes were resistant to dihydrostreptomycin during growth but sensitive to the antibiotic during sporulation. Resuspension sporulation experiments with a strB mutant showed that sensitivity to the antibiotic was acquired early in the sporulation process. The germination and outgrowth of strB spores was sensitive to the antibiotic until growth commenced, whereupon the culture was resistant. Thus the mutants are sensitive to dihydrostreptomycin during both sporulation and germination but resistant during the growth phase.

The phenotypic properties of representatives of the five genetic classes of pleiotropic-negative sporulation mutants have been investigated. Protease production, alkaline and neutral proteases, was curtailed in spoA mutants, but the remainder of mutant classes produced both proteases, albeit at reduced levels. The spoA and spoB mutants plaqued phi2 and phi15 at high efficiency, but the efficiency of plating of these phages on spoE, spoF, and spoH mutants was drastically reduced. Antibiotic was produced by the spoH mutants and to a degree by some spoF mutants, but the other classes did not produce detectable activity. The spoA mutants were less responsive to catabolite repression of histidase synthesis by glucose than was the wild type. Severe catabolite repression could be induced in spoA mutants by amino acid limitation, suggesting that the relaxation of catabolite repression observed is not due to a defect in the mechanism of catabolite repression. Although others have shown a perturbation in cytochrome regulation in spoA and spoB mutants, the primary dehydrogenases, succinate dehydrogenase and reduced nicotinamide adenine dinucleotide dehydrogenase, leading to these cytochromes are unimpaired in all mutant classes. A comparison of the structural components of cell walls and membranes of spoA and the wild type is made. The pleiotropic phenotypes of these mutants are discussed.