Primary Cultures Of Embryonic Cells Research Articles

Correlation between metabolomic profile and proliferation of Macrobrachium rosenbergii primary embryonic cell culture

Despite extensive research spanning several decades, a commercial cell line for prawns remains elusive, and we have yet to determine the ideal conditions required for successful in vitro cell cultures of crustaceans. This study marks the first application of mass spectrometry to analyze lipid content changes in prawn culture media, allowing us to investigate how specific metabolites in media correlate with cell cycle and proliferation status. To investigate these relationships, short-term cell culture experiments were conducted using three commercial media: Dulbecco's modified eagle medium (DMEM) high glucose, Opti-Minimal essential media (Opti-MEM), and DMEM:F12. We monitored metabolic activity, performed cell-cycle analysis, and used mass spectrometry to analyze lipid metabolic profiles of culture media. This comprehensive approach enables us to examine the interplay between media lipidomic content and cellular behavior. Our results revealed that all three media sustained cellular metabolic activity. DMEM high glucose and Opti-MEM showed peaks in metabolic activity at day 4, while DMEM:F12 exhibited a peak at day 7. Opti-MEM supported the shortest doubling time, making it ideal for short-term culture. Interestingly, DMEM high glucose retained more attached cells on day 1 and had the highest count on day 4, with a noticeable trend towards the G2/M cell-cycle phase. Moreover, our lipidomic analysis of Opti-MEM revealed significantly higher concentrations of 26 annotated lipids compared to the other media. Notably, lipids like phosphatidylcholine and phosphatidylserine were consistently abundant in all three media, and palmitate levels correlated with proliferation phase. These findings have significant implications for establishing sustainable crustacean cell culture lines. Understanding the lipidomic compositions and their associations with cell-cycle dynamics and proliferation allows for precise conditioning of culture media to promote sustainable growth and delay cellular entry into quiescence phases. This knowledge contributes to the long-term goal of maintaining robust prawn cell cultures for various research and biotechnological applications.

On genome editing in embryos and cells of the freshwater prawn Macrobrachium rosenbergii

The clustered regularly interspaced short palindromic repeats (CRISPR) technology provides the means for accurate genomic editing. It has been applied in many kinds of cells and animals for functional genomic studies and for precise selective breeding. Nonetheless, this method has not yet been applied in one of the most important – and well studied – decapod crustacean aquaculture species, the giant freshwater prawn Macrobrachium rosenbergii. We thus established two CRISPR platforms for M. rosenbergii—the first through direct injection into early-stage embryos (entire organism genome editing) and the second by electroporation of a primary embryonic cell culture. The systems were calibrated by optimizing Cas9 concentrations, delivery methods and editing efficiencies. Editing patterns utilizing multiple guides were examined through next generation sequencing. Our results showed a wide range of editing efficiencies in embryos, in some cases reaching as high as 100%. In contrast, in primary embryonic cell cultures, the highest editing efficiency obtained reached a maximum of 64%. In addition, there was a striking difference between the two platforms in terms of the pattern of deletions around the Cas9 cut site. This finding suggests distinct repair mechanisms in the two systems, which calls for further clarification. A phenotypic proof of concept was provided through the investigation of an early acting paired box protein 6 (Pax6) transcription factor, which showed clear effects on eye development in edited embryos and larvae. The current study lays down the foundations for precise functional genomic research and applications of genome editing in crustacean species for both aquaculture and sustainable biocontrol, opening opportunities for the creation of selected crustacean lines with distinct attributes.

Analysis on the prokaryotic microbiome in females and embryonic cell cultures of Rhipicephalus sanguineus tropical and temperate lineages from two specific localities in Brazil.

Two lineages of Rhipicephalus sanguineus are known in Brazil: the temperate or southern and the tropical or northern populations. The distribution patterns of both lineages of R. sanguineus have epidemiological implications that can affect vectorial competence concerning Ehrlichia canis, the agent of canine monocytic ehrlichiosis. Intending to identify the microbiomes of both lineages and compare microorganisms in R. sanguineus, we used the 16S rRNA (V4-V5 region) gene-based metataxonomic approach, through NGS sequencing on the MiSeq Illumina platform. We selected specimens of females from the environment and samples of primary embryonic cell cultures, from both lineages, and this was the first study to investigate the prokaryotic microbiome in tick cell cultures. The results showed that many bacterial taxa detected in the samples were typical members of the host environment. A significant diversity of microorganisms in R. sanguineus females and in embryonic cell cultures from both lineages was found, with emphasis on the presence of Coxiella in all samples, albeit in different proportions. The Coxiella species present in the two lineages of ticks may be different and may have co-evolved with them, thus driving different patterns of interactions between ticks and the pathogens that they can harbor or transmit to vertebrate hosts.

Establishment of Conditions for Long-Term Maintenance of Primary Embryonic Cell Cultures from Olive Flounder Paralichthys olivaceus.

Primary cell culture is a sufficient method frequently used to study the cellular properties and mechanisms of isolated cells in a controlled environment. In this study, an embryonic cell line (FGBC8) derived from the blastula stages of embryos of olive flounder Paralichthys olivaceus was developed. Furthermore, conditions for optimal long-term maintenance of this primary embryonic cell culture were investigated. Morphologically, FGBC8 cells were composed primarily of epithelial-like cells. FGBC8 cells were subcultured for >160 passages over ~830 days. The doubling time of FGBC8 cells was 73.8 h, and the modal diploid chromosome number was 48. FGBC8 cells transfected with green fluorescence protein (GFP)-expression plasmid exhibited a strong signal 48 h after transfection. Consequently, we demonstrated that fish serum is a crucial supplement for the long-term survival and maintenance of comparable morphology in these primary embryonic cells. Our results can be used as a guide for primary embryonic cell cultures for other fish species and may be useful for cell biotechnological applications.

Effect of exogenous factors on the induction of spicule formation in sea urchin embryonic cell cultures

The effect of exogenous factors on the realization of the spicule formation program in two sea urchin species, Strongylocentrotus intermedius and S. nudus, has been studied in primary embryonic cell cultures derived from the blastula and gastrula stages. It has been shown that the process of spicule formation depends on the type of substrate and the composition of the medium. An original finding is that calf or horse serum necessary for spicule formation in vitro can be replaced by a complex of factors including insulin, transferrin, and lectins. Methods allowing control over the growth and differentiation of marine invertebrate embryonic cells in vitro open prospects for their application to practical problems such as the establishment of cell cultures producing certain mineral structures.

Ocorrência de Borrelia spp. em cultura de células embrionárias do carrapato Boophilus microplus (Acari: Ixodidae) no Estado do Mato Grosso do Sul, Brasil

The aim of the present work was to report the occurrence of Borrelia spp. in embryonic cell cultures from naturally infected Boophilus microplus. Seven days after the beginning of a primary culture of embryonic cells of B. microplus at 31 degrees C was noted that the cells start suffering degeneration. Under examination at phase contrast microscope, the presence of prolongated microorganisms with great mobility was detected. Microscopic slides of the culture supernatant, hemolymph and egg mass, were stained by May Grünwald-Giemsa, allowing the visualization of the spirochetes. The morphologic examination of the microorganism and its visualization in. B. microplus, suggest to be Borrelia spp.

Cloning of rainbow trout (Oncorhynchus mykiss) alpha-actin, myosin regulatory light chain genes and the 5'-flanking region of alpha-tropomyosin. Functional assessment of promoters.

We report PCR cloning of rainbow trout alpha-actin (alpha-OnmyAct), myosin regulatory light chain (OnmyMLC2) genes and the 5'-flanking region of alpha-tropomyosin (alpha-OnmyTM). Being expressed in skeletal and cardiac muscle, alpha-OnmyAct was a predominant isoform in trunk muscle of adult rainbow trout. Exon structure of this gene was identical to all known vertebrate skeletal and to some of the cardiac alpha-Act genes. Two distinct OnmyMLC2 promoters were cloned and both included transposon-like sequences. The coding part of OnmyMLC2 consisted of seven exons whose length was typical for vertebrate MLC2 genes. The upstream regions of alpha-OnmyAct and OnmyMLC2 included a TATA box and a number of putative regulatory motifs (E-boxes in all three sequences and CArG-boxes in alpha-OnmyAct), whereas there were no canonical motifs in the alpha-OnmyTM promoter. LacZ reporter gene was fused with the 5'-flanking regions of alpha-OnmyAct, two OnmyMLC2 genes and alpha-OnmyTM promoters. These constructs were transferred into rainbow trout eggs. At the stage of 39 somite pairs, LacZ reporter was detected in the myotomes, neural plate and neural crest, brain and yolk syncytial layer of all analysed embryos. alpha-OnmyTMLacZ was also expressed in the heart. Functionality of promoters and the alpha-OnmyAct terminator was confirmed in rainbow trout primary embryonic cell cultures. We cloned rainbow trout glucose transporter type I (OnmyGLUT1) into vectors including the alpha-OnmyAct and OnmyMLC2 promoters and the alpha-SkAct terminator. Recombinant OnmyGLUT1 transcripts were detected in rainbow trout embryos during somitogenesis.

Macrophages in Drosophila embryos and L2 cells exhibit scavenger receptor-mediated endocytosis.

Mammalian macrophage scavenger receptors exhibit unusually broad binding specificity and are implicated in atherosclerosis and host defense. Scavenger receptor-like endocytosis was observed in Drosophila melanogaster embryos and in primary embryonic cell cultures. This receptor activity was expressed primarily by macrophages. The Drosophila Schneider L2, but not the Kc, cell line also exhibited a scavenger receptor-mediated endocytic pathway similar to its mammalian counterpart. L2 receptors mediated high-affinity internalization and subsequent temperature- and chloroquine-sensitive degradation of 125I-labeled acetylated low density lipoprotein and displayed characteristic ligand specificity. These findings suggest that scavenger receptors mediate important, well-conserved functions and raise the possibility that they may be pattern recognition receptors that arose early in the evolution of host defense mechanisms. They also establish additional systems for the investigation of endocytosis in Drosophila and scavenger receptor function in disease, host defense, and development.

Drosophila neurotactin mediates heterophilic cell adhesion.

Neurotactin is a 135 kd membrane glycoprotein which consists of a core protein, with an apparent molecular weight of 120 kd, and of N-linked oligosaccharides. In vivo, the protein can be phosphorylated in presence of radioactive orthophosphate. Neurotactin expression in the larval CNS and in primary embryonic cell cultures suggests that it behaves as a contact molecule between neurons or epithelial cells. Electron microscopy studies reveal that neurotactin is uniformly expressed along the areas of contacts between cells, without, however, being restricted to a particular type of junction. It putative adhesive properties have been tested by transfecting non adhesive Drosophila S2 cells with neurotactin cDNA. Heat shocked transfected cells do not aggregate, suggesting that neurotactin does not mediate homophilic cell adhesion. However, these transfected cells bind to a subpopulation of embryonic cells which probably possess a related ligand. The location at cellular junctions between specific neurons or epithelial cells, the heterophilic binding to a putative ligand and the ability to be phosphorylated are consistent with the suggestion that neurotactin functions as an adhesion molecule.

Cell lines from imaginal discs of Drosophila melanogaster.

New cell lines, designated as ML-DmD1-10, were established from dissociated imaginal discs of Drosophila melanogaster. The culture medium was prepared by mixing in a 1:1 ratio Cross and Sang's M3(BF) medium, supplemented with 10% heat inactivated fetal bovine serum (FBS), with the supernatant of a primary embryonic cell culture made in the M3(BF) medium and supplementing this mixture with insulin. One cell line was established in the medium containing larval hemolymph instead of the primary culture supernatant, and another was established in fresh M3(BF) medium supplemented with insulin and FBS. In these mediums, imaginal disc cells first formed aggregates and cellular vesicles within a few weeks followed by the proliferation of thin-layered cells around them after about 1 mo. Ten cell lines have so far been established from two kinds of imaginal discs and disc mixtures. The ploidy of these cell lines was predominantly diploid. Population doubling time was about 50 to 70 h at 3 to 10 mo. after initiation of the culture. When the cell aggregates formed in vitro were implanted in metamorphosing larvae, they differentiated at high frequency into adult cuticular structures in the early phase of the primary culture. This differentiation of aggregates was also observed, though at low frequency, in a culture maintained by dilution-transfer for 6 to 15 mo. in vitro.

Teratogens induce a subset of small heat shock proteins in Drosophila primary embryonic cell cultures.

Drosophila embryonic cells placed into culture just after gastrulation differentiate in vitro over the next 24 hr. A number of drugs that are teratogenic in mammalian systems have been found to inhibit muscle or neuron differentiation (or both) in these developing cultures. We have examined, by two-dimensional gel electrophoresis, the effects of these drugs on protein synthesis in embryonic cells. For nine teratogens tested, cells treated for 20 hr with the drug show a dramatic induction of three proteins of about 20 kilodaltons, in addition to the normal proteins synthesized by untreated cells. Three teratogens as well as all eight nonteratogens tested did not show this induction. The induced proteins appear to be identical to three of the heat shock proteins (hsp 23, 22a, and 22b), as shown by electrophoretic mobilities and peptide mapping by partial proteolysis. A 37 degrees C heat shock of the embryonic cells produces the full complement of heat shock proteins, whereas drug-treated cells induce only the subset hsp 23, 22a, and 22b but not hsp 26 or 27. beta-Ecdysterone, the Drosophila molting hormone, also inhibits embryonic differentiation and induces hsp 23, 22a, and 22b, a partial subset of the heat shock proteins (hsp 22, 23, 26, and 27) induced by the hormone in imaginal discs and some Drosophila continuous cell lines. Dose-response studies of several drugs show a correlation between the degree of inhibition of differentiation and the level of induction of hsp 23, 22a, and 22b. The induction of heat shock proteins by drugs may reflect specific types of stress that can also give rise to teratogenesis.

Glycoprotein patterns in different established cell lines of Drosophila melanogaster responding to 20-hydroxyecdysone

Newly synthesized glycoproteins labelled with [ 3 H]N- acetyl- d- glucosamine were studied by two-dimensional gel electrophoresis in a primary culture of embryonic cells and in five established cell lines independently obtained from embryonic cells of Drosophila melanogaster. The patterns of major glycoprotein fractions were different in different cell lines, whereas the protein spectra proved to be basically similar. Characteristic glycoprotein patterns were maintained after prolonged cultivation. Four “obligatory” acid glycoprotein fractions were shown to be present in all the tested cell cultures. All the independent lines, except vg and the primary cell culture, proved to contain a family of glycoproteins (or its components) with similar properties. The family contained up to 12 discrete components with similar molecular weights but with different isoelectric points. The various components constituting the family were labelled to different degrees in the different lines. 20-Hydroxyecdysone either increased the net synthesis of the most acid fractions in the family (line D) or induced the synthesis of the majority or all of the 12 fractions making up the family (lines G 2 and pE). The effects of the hormone on glycoprotein net synthesis were insignificant in lines Schneider-2, vg and in a primary culture of embryonic cells. The results demonstrate that the tested cell cultures possess different levels of competence for 20-hydroxyecdysone, which can induce the synthesis of a specific glycoprotein family.

Developmental modulation of protein synthesis in Drosophila primary embryonic cell cultures

AbstractThe patterns of proteins synthesized during embryonic development in Drosophila melanogaster have been examined by two‐dimensional gel electrophoresis. Primary cell cultures prepared from donor embryos synchronized to ± 1 hr were labeled with [35S]methionine at 5, 11.5, 14.5, and 26 hr after oviposition. Of approximately 400 to 500 proteins detected, the synthesis of about 50 is developmentally modulated. The greatest number of changes in the synthesis of stage‐specific proteins occurs at 11.5 and 14.5 hr after oviposition, periods just prior to and during the times of the greatest overt morphological and biochemical changes. At 11.5 hr, 35 stage‐specific proteins are synthesized, including 19 that are not present at the previous stage examined. At 14.5 hr, 34 stage‐specific proteins can be detected, including 11 newly synthesized proteins. However, 12 proteins from the previous stage are no longer synthesized. At the completion of embryonic differentiation, at 26 hr, no new proteins are synthesized and the synthesis of many present in earlier stages has decreased or stopped. Comparison of patterns of embryonic proteins to those synthesized by two Drosophila continuous cell lines reveals that the majority of proteins are common to all. However, only about 40% of the embryonic stage‐specific proteins are present in either cell line. In addition, there are several proteins unique to each cell line that are not observed in any of the embryonic stages.

A new tick cell line derived from Boophilus microplus

The Boophilus microplus IX tick cell line was developed from a primary embryonic cell culture derived from eggs six to nine days old. The cell line has been in culture since March 1979 and is currently maintained at 32 degrees C in medium consisting of equal parts of minimum essential medium an Leibovitz 15 medium supplemented with 20 per cent fetal bovine serum, 10 per cent tryptose phosphate broth and 0.1 per cent plasma albumin. A split ratio of 1:2 has been used for all subcultures and the cell line is now in its 26th passage. The cells are predominantly epithelial-like and of the male diploid chromosome number 21.

Actin heterogeneity in primary embryonic culture cells from Drosophila melanogaster

We have investigated actin heterogeneity in differentiating primary embryonic cell cultures from Drosophila melanogaster. Proteins labeled with [ 35S]methionine have been separated using O'Farrell two-dimensional gel electrophoresis. Cultures of heterogeneous cell types synthesize at least three major forms of actin, each differing slightly in isoelectric point. We have used a cell separation technique based on differential cell adhesion in the presence of ethylene glycol-bis(β-aminoethyl ether) N,N′-tetraacetate to prepare cultures either highly enriched for, or highly depleted of, myogenic cells. Postfusion myogenic cells synthesize predominantly the most acidic actin form (actin I), while nonmyogenic cells synthesize almost exclusively the two more basic forms (actins II and III). Synthesis of actins at earlier intervals in myogenic cell differentiation in vitro has also been examined. Immediately prior to the onset of myoblast fusion, the synthesis of actin I represents approximately 40% of total actin synthesis. As myogenic cell differentiation progresses this actin form is synthesized at an increasing rate, relative to actins II and III. Drosophila appears to be quite similar to vertebrates with regard to the number of actin species synthesized, as well as to cell and developmental specificity of actin synthesis.

Isolation and partial characterization of Drosophila myoblasts from primary cultures of embryonic cells.

We describe a method for preparing highly enriched cultures of Drosophila myoblasts from a heterogeneous cell population derived from gastrulating embryos. Enriched cultures are prepared by plating this heterogeneous population of cells in medium from which much of the free calcium is chelated by ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetate (EGTA). Adhesion of myoblasts to tissue culture plastic is better than that of other cell types when plated in this medium. Data concerning cell identity, timing of S phase, and fusion kinetics document the degree of enrichment for myogenic cells and illustrate their synchronous differentiation in vitro.

Amounts of isoaccepting lysine tRNAs change with the proliferative state of cells.

VARIATIONS in isoaccepting tRNA populations occur in mammalian cells during development, neoplasia, and virus infection, and such changes may reflect the involvement of tRNA in regulatory processes1,2, although firm evidence to that effect is not available. Ortwerth and Liu3 have shown that in normal or neoplastic cells an isoaccepting species of lysine tRNA, tRNA4Lys, is present in dividing cells but absent from non-dividing cells. Ortwerth et al.4 determined some of the functional properties of tRNA4Lys from various tissues and obtained evidence that the species is a real isoacceptor of tRNALys rather than an artefact. Normal, proliferating cells that were examined had only relatively small amounts of tRNA4Lys; however, a larger proportion of the isoacceptor was found in neoplastic cells such as mouse leukaemia and Morris hepatoma cells. It is desirable, therefore, to establish whether the large amount of tRNA4Lys is peculiar to the neoplastic state or whether normal cells may also have large amounts of that isoacceptor under some growth conditions. Therefore, we studied isoaccepting lysyl-tRNA profiles from mouse cells in different states of proliferation: adult liver, embryo and growing and quiescent primary cultures of embryonic cells. We found that normal growing cells also have an appreciable amount of tRNA4Lys.

Primary cultures of embryonic cells from the snail Biomphalaria glabrata.

Whole egg masses or separated capsules containing trochophore-stage embryos of Biomphalaria glabrata were axenized in dilute hypochlorite with or without antibiotics. Embryos were extracted in snail saline and teased into fragments which were dissociated (generally with trypsin) and seeded into media. Of numerous formulations used, 4 were equally good: 3 are based upon diluted medium 199 or NCTC-135, with additions, and the other was formulated from analyses of hemolymph and published values; 3 are used under 5% CO2 and the other in air. Osmolalities vary from 116 to 220 mOsm/Kg H20. Fetal bovine serum is added to all and appears necessary to sustain cell growth. Cultures were not enhanced by use of collagen coatings, plasma clots, or adult snail extracts. Snail hemolymph is toxic when fresh and ineffective after heat inactivation. Five cell types were seen: fibroblast-like, principally in the first 2 weeks; epithelial-like, sometimes making sheets or monolayers; attenuated contractile muscle cells which sometimes became broad and binucleate; macrophage-like; and hemocytes. Numerous mitotic figures have been observed in aceto-orcein squash preparations, especially after incubation with colcemid. Cultures were usually healthy until terminated up to 6 weeks old.

Growth of Venezuelan encephalitis virus in embryonic cell cultures of wild birds.

Primary embryonic cell cultures made from nine species of wild and domestic birds were infected with Venezuelan encephalitis virus and reproduced each strain to moderately high levels.

“Cytoplasmic” DNA from primary embryonic cell cultures is not informational

FEBS LettersVolume 20, Issue 1 p. 108-110 Full-length articleFree Access “Cytoplasmic” DNA from primary embryonic cell cultures is not informational R. Williamson, R. Williamson The Beatson Institute for Cancer Research 132 Hill Street, Glasgow, C.3, ScotlandSearch for more papers by this authorT. Mcshane, T. Mcshane The Beatson Institute for Cancer Research 132 Hill Street, Glasgow, C.3, ScotlandSearch for more papers by this authorM. Grunstein, M. Grunstein Institute of Animal Genetics, University of Edinburgh Edinburgh 9, ScotlandSearch for more papers by this authorR.A. Flavell, R.A. Flavell Department of Biochemistry, University of Hull, Hull, EnglandSearch for more papers by this author R. Williamson, R. Williamson The Beatson Institute for Cancer Research 132 Hill Street, Glasgow, C.3, ScotlandSearch for more papers by this authorT. Mcshane, T. Mcshane The Beatson Institute for Cancer Research 132 Hill Street, Glasgow, C.3, ScotlandSearch for more papers by this authorM. Grunstein, M. Grunstein Institute of Animal Genetics, University of Edinburgh Edinburgh 9, ScotlandSearch for more papers by this authorR.A. Flavell, R.A. Flavell Department of Biochemistry, University of Hull, Hull, EnglandSearch for more papers by this author First published: January 15, 1972 https://doi.org/10.1016/0014-5793(72)80029-2Citations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. References 1 M.K. Bach, Proc. Natl. Acad. Sci. U.S., 48, (1962), 1031– 2 M.K. Bach, H.G. Johnson, Biochemistry, 6, (1967), 1916– 3 H.E. Bond, J.A. Cooper, D.P. Courington, J.S. Wood, Science, 165, (1969), 705– 4 W.C. Schneider, E.L. Kuff, J. Biol. Chem., 244, (1969), 4843– 5 E. Bell, Nature, 224, (1969), 326– 6 S.R. Pelc, Exp. Cell Res., 14, (1958), 301– 7 S.R. Pelc, Nature, 219, (1968), 162– 8 R. Williamson, J. Mol. Biol., 51, (1970), 157– 9 D. Fromson, M. Nemer, Science, 168, (1970), 266– 10 W.E.G. Muller, R.K. Zahn, R. Beyer, Nature, 227, (1970), 1211– 11 J.A. Bryant, D.C. Wildon, Biochem. J., 121, (1971), 5P– 12 R.J. Britten, D.E. Kohne, Science, 161, (1968), 529– 13 R.J. Britten, E.H. Davidson, Science, 165, (1969), 349– 14 W.G. Flamm, P.M.B. Walker, M. McCallum, J. Mol. Biol., 40, (1969), 423– 15 R.A. Flavell, I.G. Jones, Biochim. Biophys. Acta, 232, (1971), 255– 16 L.H. Kedes, M.L. Birnstiel, Nature New Biology, 230, (1971), 165– 17 B.L. McConaughy, C.D. Laird, B.J. McCarthy, Biochemistry, 8, (1969), 3289– 18 E.M. Scolnick, S.A. Aaronson, G.J. Todaro, W.P. Parks, Nature, 229, (1971), 318– 19 J. Ross, E.M. Scolnick, G.J. Todaro, S.A. Aaronson, Nature New Biology, 231, (1971), 163– Citing Literature Volume20, Issue1January 15, 1972Pages 108-110 ReferencesRelatedInformation