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Friend leukemia
About: Friend leukemia is a research topic. Over the lifetime, 319 publications have been published within this topic receiving 7463 citations.
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01 Jan 1975
TL;DR: The greater number of polypeptides in endogenous virus suggests that the pattern may be derived from a mixture of particles, as suggested previously by others, and some evidence for mutual interaction between FLV and coproduced endogenous viruses is presented.
Abstract: Abstract The polypeptide patterns of con A-isolated Friend leukemia virus and other particles of density 1.18 that are spontaneously produced by Friend-infected and uninfected BALB c mouse cells are analyzed in high-resolution SDS-acrylamide gradient gels. Agglutination of virions by con A and fractionation of α-methyl mannose-dissociated complexes in sucrose equilibrium gradients yields a pattern associated with FLV (density 1.16) that contains at least 20 polypeptides of MW 30,000–218,000. The pattern includes the major structural polypeptide of MuLV, MW 34,000, and, compared to published patterns, it has a lower proportion of smaller polypeptides. Relative to serum albumin, a major component of culture medium, virion polypeptides are purified at least 50,000-fold, and the specific leukemia virus infectivity of isolates is approximately 1 PFU/800 particles. Though they are morphologically indistinguishable from FLV, and similarly contain viral 60–70 S RNA, spontaneously arising BALB c endogenous viruses (density 1.18) possess a recognizable complement of at least 26 polypeptides including a major one of MW 44,000. The pattern includes a glycopolypeptide of MW 14,000 that is not found in FLV. Like the FLV pattern, the majority of polypeptides are of MW 30,000–218,000. The greater number of polypeptides in endogenous virus suggests that the pattern may be derived from a mixture of particles, as suggested previously by others, and some evidence for mutual interaction between FLV and coproduced endogenous viruses is presented.
TL;DR: The fetal antigen allows a clearcut distinction between the tumoral step from which emerge the Friend and erythro-proliferative cells.
TL;DR: The mechanisms that presumably regulate the appearance of SIL resistance in Sendai infected FLC are discussed and the maintenance of the resistant phenotype of the clones requires the serial subcultivation of the cells in the presence of activated EGSV.
TL;DR: Increased activity of serum DNase I and of splenic inhibitor ofDNase I was found during the development of Friend's virus leukemia and increased activity of inhibitor in the spleen also was discovered after intravenous injection of exogenous DN enzyme I into mice.
Abstract: An increase in the DNAase 1 activity in the serum and an increase in the DNAase inhibitor activity in the spleen in the development of virus Friend leukemia were demonstrated. Increased activity of the inhibitor in the spleen was also revealed after intravenous injection of exogenous DNAase 1 into mice. A potential role of serum DNAase 1 in the development of experimental leukemia is discussed.
TL;DR: It is postulated that the reduced virus production in adhesive FF monolayers is due to as yet undetermined events taking place during virus maturation at a time coincident with that of cell-cell adhesion under conditions of culture confluency.
Abstract: The replication of Friend Leukemia virus (FLV) has been investigated in adhesive clones (FF) of Friend Leukemia cells which were selected via cultivation on top of human fibroblast monolayers. In these adhesive clones a shut-down of FLV production is observed under conditions of culture confluency; this finding is not due either to a reduced number of cell divisions nor to a defective expression of FLV genome as assessed by Northern blot and immunofluorescence studies. Ultrastructural studies showed that virus budding and release into the medium is not detectable under these conditions. Conversely, in confluent FF cell monolayers abundant imperfect type-A enveloped particles were visible, possibly originating from stacks of granular endoplasmic reticulum with thickened membranes.