Transgenic Research

, Volume 9, Issue 6, pp 417–427 | Cite as

Copy Number Related Transgene Expression and Mosaic Somatic Expression in Hemizygous and Homozygous Transgenic Tilapia (Oreochromis Niloticus)

  • M. Azizur Rahman
  • Gyu-Lin Hwang
  • Shaharudin Abdul Razak
  • Frédéric Sohm
  • Norman Maclean


Three lines of transgenic tilapia (Oreochromisniloticus) fish were generated with a constructcontaining a lacZ reporter gene spliced to a 4.7 kb 5′ regulatory region of a carp beta actin gene. All these three lines contain different copy numbers oftransgenes and the levels of lacZ expressionwere found to be related to transgene copy number.Mosaic patterns of somatic lacZ expression wereobserved in these three lines which differed between linesbut were consistent within a line. We also observedthat expression of the reporter gene in homozygoustransgenic fish was approximately two-fold greater thanin the hemizygous transgenics. Analysis of expressionof the reporter gene on a tissue-to-tissue basisdemonstrated that lacZ expression of thereporter gene in stably transformed fish occured withvariable intensity in different organs and tissues andwas also sometimes variable in different cells of thesame tissue in G1and G2 generations of the transgenic lines.

β-galactosidase mosaic expression transgenic fish 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alvarez MC, Otis J, Amores A and Guise K (1991) Short-term cell culture technique for obtaining chromosomes in marine and fresh water fish. J Fish Biol 39: 817–824.Google Scholar
  2. Assaad FF, Tucker KL and Signe ER (1993) Epigenetic repeatinduced gene silencing (RIGS) in Arabidopsis. Plant Mol Biol 22: 1067–1085.Google Scholar
  3. Bradford MM (1976) A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the protein-dye binding. Anal Biochem 72: 248–254.Google Scholar
  4. Braell WA (1991) β-galactosidase assay using the TKO 100 mini-fluorometer. Hoefer Scientific Instruments, Technical Bulletin no 129.Google Scholar
  5. Chávez S and Aguilera A (1997) The yeast HPR1 gene has a functional role in transcriptional elongation that uncovers a novel source of genome instability. Genes Dev 11: 3459–3470.Google Scholar
  6. Cohen-Tannoudji M, Vandormael-Pournin S, Drezen J-M, Mercier P, Babinet C and Morello D (2000) LacZ sequences prevent regulated expression of house keeping genes. Mechanisms Dev 90: 29–39.Google Scholar
  7. Collas P (1998) Modulation of plasmid DNA methylation and expression in zebrafish embryos. Nucleic Acids Res 26: 4454–4461.Google Scholar
  8. de Carvalho F, Gheysen G, Kushnir S, Montagu MV, Inzé D and Castresana C (1992) Suppression of β-1,3-glucanase transgene expression in homozygous plants. EMBO J 11: 2995–2602.Google Scholar
  9. Dobie K, Mehtali M, McCleanaghan M and Lathe R (1997) Varie-gated gene expression in mice. Trends in Genet 13: 127–130.Google Scholar
  10. Dorer DR (1997) Do transgene arrays form heterochromatin in vertebrates? Transgenic Res 6: 3–10.Google Scholar
  11. Fraser P and Grosveld F (1998) Locus control region chromatin activation and transcription. Curr Opinion Cell Biol 10: 361–365.Google Scholar
  12. Henikoff S (1998) Conspiracy of silence among repeated transgenes. BioEssays 20: 532–535.Google Scholar
  13. Knotts S, Rindt H and Robbins J (1995) Position independent expression and developmental regulation is directed by the β myosin heavy chain gene's 5′ upstream region in transgenic mice. Nucleic Acid Res 23: 3301–3309.Google Scholar
  14. Manuelidis L (1991) Heterochromatic features of an 11-megabase transgene in brain cells. Proc Natl Acad Sci USA 88: 1049–1053.Google Scholar
  15. Mehtali M, LeMeur M and Lathe R (1990) The methylation-free status of a housekeeping transgene is lost at high copy number. Gene 91: 179–184.Google Scholar
  16. Moav B (1994) Developmental and molecular genetics in Fish. Israel J Zool 40: 441–466.Google Scholar
  17. Nillson E and Lendahl U (1993) Transient expression of a human beta-actin promoter lacZ gene introduced into mouse embryos correlates with a low degree of methylation. Mol Reprod Dev 34(2): 149–157.Google Scholar
  18. Rahman MA, Iyengar A and Maclean N (1997) Coinjection strategy improves integration efficiency of a growth hormone gene construct resulting in lines of transgenic tilapia (Oreochromis niloticus) expressing an exogenous growth hormone gene. Transgenic Res 6: 369–378.Google Scholar
  19. Razak SA, Hwang G-L, Rahman MA, Rahman MA, Maclean N (1999) Growth performance and gonadal development of growth enhanced transgenic tilapia Oreochromis niloticus (L.) following heat-shock-induced triploidy. Mar Biotechnol 1: 533–544).Google Scholar
  20. Robertson G, Garrick D, Wilson M, Martin DIK and Whitelaw E (1996) Age-dependent silencing of globin transgenes in the mouse. Nucleic Acid Res 24: 1465–1471.Google Scholar
  21. Sands AT, Hansen TN, Demayo FJ, Stanley LA, Xin L and Schwartz RJ (1993) Cytoplasmic beta-actin promoter produces germ-cell and preimplantation embryonic transgene expression. Mol Reprod Dev 34: 117–126.Google Scholar
  22. Shawlot W, Deng JM, Fohn LE and Behringer RR (1998) Restricted beta-galactosidase expression of a hygromycin-lacZ gene targeted to the beta-actin locus and embryonic lethality of beta-actin mutant mice. Transgenic Res 7: 95–103.Google Scholar
  23. Smith HA, Swaney SL, Parks TD, Wernsman EA and Dougherty WG (1994) Transgenic plant-virus resistance mediated by untranslatable sense RNAs-Expression, regulation and fate of non-essential RNAs. Plant Cell 6: 1441–1453.Google Scholar
  24. Tam PP and Tan SS (1992) The somitogenetic potential of cells in the primitive streak and the tail bud of the organogenesis-stage mouse embryo. Development 115: 703–715.Google Scholar
  25. Thorey IS, Meneses JJ, Neznanov N, Kulesh DA, Pedersen RA and Oshima RG (1993) Embryonic expression of human keratin 18 and K18-β-Galactosidase fusion genes in transgenic mice. Dev Biol 160: 519–534.Google Scholar
  26. Whitelaw BA, Harris S, McCleanaghar M, Simons PJ and Clark JA (1992) Position-independent expression of the ovine β-lactoglobulin gene in transgenic mice. Biochem J 286: 31–39.Google Scholar

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • M. Azizur Rahman
    • 1
  • Gyu-Lin Hwang
    • 1
  • Shaharudin Abdul Razak
    • 1
  • Frédéric Sohm
    • 1
  • Norman Maclean
    • 2
  1. 1.Division of Cell Sciences, School of Biological SciencesUniversity of SouthamptonSouthamptonUnited Kingdom
  2. 2.Division of Cell Sciences, School of Biological SciencesUniversity of SouthamptonSouthamptonUnited Kingdom

Personalised recommendations