Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rabbit lymphosarcoma tissues contain 70 S RNA and RNA-directed DNA polymerase encapsulated in particulate components that band in the density region of type C RNA viruses. RNA-directed DNA polymerase associated with the particles could be distinguished from cellular DNA polymerases by salt elution from phosphocellulose. The enzyme preferred the template primers poly(rA)-(dT)12-18 and poly(rC)-(dG)12-18 over other synthetic template primers and also utilized viral 70 S RNA as template; these properties are not observed with the known cellular DNA polymerases.
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PMID:Presence of a high-molecular-weight RNA and RNA-directed DNA polymerase in rabbit hereditary lymphosarcoma. 6 26

Northern poke lymphosarcoma DNA polymerase was partially purified from particulate fractions banding at 1.15 to 1.16 g/ml from homogenates prepared from frozen necropsies of tumor-bearing pike. The enzyme behaves as a typical reverse transcriptase, in that it prefers ribotemplates to deoxytemplates. The isoelectric point (pl 5.5) is similar to that of avian myeloblastosis virus polymerase. The pike enzyme elutes from a phosphocellulose column at 0.22 M potassium phosphate, the same as avian myeloblastosis virus DNA polymerase. The enzyme activity is inhibited by pyran, a specific inhibitor of viral DNA polymerases. The most striking difference between the pike lymphoma polymerase and the other viral DNA polymerases tested is the low maximum temperature of 20 degrees, compared to 30 degrees for Rauscher leukemia virus polymerase and 38 degrees for avian myeloblastosis virus and Rous sarcoma virus.
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PMID:Presence of DNA polymerase in lymphosarcoma in northern pike (Esox lucius). 6 92

Type C RNA virus(es) was readily released from primary lymphosarcoma cell cultures of WH/J rabbits after induction with halogenated pyrimidines. The virus contained an RNA-directed DNA polymerase and the p30 structural protein. The rabbit virus RNA-directed DNA polymerase and p30 protein shared antigenic homologies with other mammalian type C oncornaviruses but appear to also possess unique antigenic determinants. Normal rabbit liver contained DNA homologous to a 3H-labeled complementary DNA transcript of the rabbit viral genome, indicating that type C viral genetic information is present in at least the WH/J strain of rabbits.
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PMID:Induction of type C RNA virus from cultured rabbit lymphosarcoma cells. 8 Apr 60

Murine xenotropic virus, designated 698/X, was recovered by implantation of human lymphosarcoma-derived cells U-698M into nude mice of Giovanella's colony. The budded and extracellular particles revealed typical type-C morphology, the latter possessing reverse transcriptase (RT) activity and exhibiting a buoyant density 1.17 g/ml in sucrose gradient. In competitive radioimmunoassay using iodinated p30 of Rauscher MuLV, the 698X viral concentrate and cell extracts of both implanted lymphosarcoma cells (U-698M-N-1 and U-715M-N-1) were as effective as Gross MuLV, thus indicating the murine origin of the virus. The propagation of the 698/X virus in five human, four mouse (permissive for N- and B-tropic MuLV), two rat and one bovine cell lines was followed by RT, XC syncytia assays and EM investigations. The replication of the 698/X virus seems to be restricted mainly to both human lymphosarcoma-derived cell lines U-698M and U-715M. The new recovery of the virus from the nude mouse by implantation of U-175M cells has asserted its high tropism to human lymphosarcoma cells and its murine origin. The comparative response of mouse, rabbit and rat cells exposed to both NZB and 698/X xenotropic murine viruses exhibited host range differences between these viruses. The rabbit SIRC and rat embryonic cells REC were fully permissive for the murine xenotropic NZB virus, while low viral production was detected by RT assay only in 698/X virus infected SIRC cells.
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PMID:Preferential replication of murine xenotropic type-C virus in human lymphosarcoma-derived cell lines. 9 7

The naphthoquinone moiety was proven to be essential to the biological activities of sakyomicin A using various naphthoquinone derivatives. Among the naphthoquinones tested, juglone (5-hydroxy-1,4-naphthoquinone) which resembles the partial structure of sakyomicin A was the most active in cytotoxicity against murine lymphosarcoma L5178Y cells, electron acceptor function in the oxidation of NADH by Clostridium kluyveri diaphorase or rat liver mitochondria and inhibition against avian myeloblastosis virus reverse transcriptase. The significantly lower cytotoxicity of sakyomicin A as compared with juglone was attributable to its poor membrane transport. The inhibition of reverse transcriptase activity may result from the interaction between a sulfhydryl group in the active center of the enzyme and quinone groups of the naphthoquinones and sakyomicin A.
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PMID:Role of the naphthoquinone moiety in the biological activities of sakyomicin A. 242 91

Newborn sheep inoculated with phytohemagglutinin (PHA)-treated short-term, cultures of lymphocytes from cattle infected with bovine leukemia virus (BLV) or with a BLV- infected long-term culture of bovine leukemic lymphocytes became persistently infected with BLV. Fifty percent or more of the sheep died with histologically confirmed lymphosarcomas. Cytogenetic studies of representative cases demonstrated that the tumors did not result from the progressive growth of neoplastic lymphocytes in the inoculum but rather from the neoplastic transformation of the recipients lymphoid cells. Neither BLV infection nor lymphosarcoma was observed in control uninoculated sheep or in sheep given injections of PHA-treated cultures of lymphocytes from BLV-free cows. The virus recovered from the tumorous sheep was indistinguishable from BLV morphologically, antigenically, and biologically, and its reverse transcriptase had the same cation preference and immunologic properties as the BLV enzyme. Persistent BLV infection and lymphosarcoma were also observed in a group of sheep inoculated neonatally with BLV-containing cell-free culture supernatants. These results extend previous observations on the high susceptibility of sheep to BLV infection and provide definitive evidence that BLV is a tumor-inducing virus.
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PMID:Induction of lymphosarcoma in sheep by bovine leukemia virus. 617 Jul 71

Lymphoid tissue from 43 cases of canine lymphosarcoma and from 40 clinically normal dogs have been examined for markers of retrovirus infection. From 69-76% of culture supernatants from lymphosarcomas were shown to contain particles of retroviral density and to possess poly rC-oligo dG templated polymerase (reverse transcriptase) activity compared with 17-24% of culture supernatants from normal canine lymphoid cells. In 6 culture supernatants from cases of lymphosarcoma, high molecular weight 60-70S RNA was detected and shown to be found in association with this particulate reverse transcriptase activity. No such RNA was detected in 6 culture supernatants from normal canine lymphoid cells.
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PMID:Reverse transcriptase activity and particles of retroviral density in cultured canine lymphosarcoma supernatants. 618 65

Cats were classified into 4 categories by immunofluorescence antibody assay for the presence of feline leukemia virus (FeLV) and histologically as a) normal, FeLV-, b) normal, FeLV+, c) lymphosarcoma (LSA), FeLV+, and d) LSA, FeLV-. Determinations by Raji cell radioimmunoassay modified for cat serum revealed circulating immune complex (CIC) levels of healthy cats to be less than or equal to 50 micrograms equivalent aggregated cat immunoglobulin/ml (microgram/ml). In contrast, sera of cats in groups b, c, and d all contained significantly higher CIC levels (up to 12,000 micrograms/ml) associated with marked hypocomplementemia and C activation occurring via the classical pathway. Sera from FeLV+, LSA+ cats with high levels of CIC and sera of healthy cats were fractionated according to size and bouyant density by centrifugation through 10 to 40% sucrose gradients. Analysis of fractions from LSA+, FeLV+ sera revealed that both immune complexes (ICs), FeLV reverse transcriptase (RT), and IgG were present in fractions corresponding to a bouyant density of 1.15 to 1.18 g/ml. The CIC containing fractions activated C by the classical pathway. Sera from normal cats did not have CIC or RT and none of the fractions activated the classical pathway. These data suggest that vital antigen-antibody complexes are present in sera of viremic cats with LSA and these complexes activate the C system.
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PMID:Circulating immune complexes associated with naturally occurring lymphosarcoma in pet cats. 625 67

Two aged mares with histiolymphocytic lymphosarcoma had multiple rapidly proliferating tumours in the subcutis. Consistent haematological changes were absent. One mare had lymph node involvement but no neoplastic lesions in the viscera. Microbiological examination of tumour tissue showed coryneform bacteria; there was no evidence of C-type or lytic viruses or of reverse transcriptase. Prominent intramitochondrial crystalline inclusions were in histiocytic tumour cells.
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PMID:Histiolymphocytic lymphosarcoma in the subcutis of two horses. 689 64

The QT35 cell line, established from 20-methylcholanthrene (MCA)-induced tumours in Japanese quail, is positive for Marek's disease virus (MDV), and therefore we examined whether MDV is important for the development of MCA-induced tumours. Japanese quail were inoculated with the JM16 strain of MDV at 1 or 3 days of age or left uninoculated. At 3 weeks of age, quail were injected in the breast muscle with 4 mg MCA in corn oil or corn oil alone. Quail were observed for tumours three times/week and at post mortem at 11 to 12 weeks of age. MDV DNA was detected by polymerase chain reaction (PCR) in spleens of 14/20 birds inoculated with JM16+corn oil and of 53/71 birds inoculated with JM16+MCA. Interestingly, 1/74 quail was positive in the MCA group alone for MDV DNA. Tumours were collected for histopathology, cell line development, and PCR and reverse transcriptase-PCR for the presence of MDV. Tumours developed in 38/83 MCA-treated and 32/85 JM16+MCA-treated quail. Fibrosarcomas without metastasis were the only tumours observed in the MCA-treated quail, while quail treated with JM16 and MCA developed undifferentiated tumours, fibrosarcomas, lymphosarcomas or combinations with or without metastasis. One out of 20 quail receiving JM16 alone developed a lymphosarcoma. Cell line development was not influenced by JM16. Tumours from MCA-treated quail were negative for MDV, while 19/29 were positive in the JM16+MCA group. MDV transcripts were present in 13/18 tumours examined in the JM16+MCA group. In conclusion, MDV did not affect tumour development but did influence tumour aggression and histological type.
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PMID:Role of Marek's disease herpesvirus in the induction of tumours in Japanese quail (Coturnix coturnix japonica) by methylcholanthrene. 2054 24


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