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  • 1
    ISSN: 1573-9368
    Keywords: β-actin gene ; goldfish ; promoter ; transcription ; zebrafish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transcriptional regulatory elements of the β-actin gene of carp (Cyprinus carpio) have been examined in zebrafish and goldfish harbouring transgenes. The high sequence conservation of the putative regulatory elements in the β-actin genes of animals suggested that their function would be conserved, so that transgenic constructs with the same transcriptional control elements would promote similar levels of transgene expression in different species of transgenic animals. To test this assumption, we analysed the temporal expression of a reporter gene under the control of transcriptional control sequences from the carp β-actin gene in zebrafish (Brachydanio rerio) and goldfish (Carrasius auratus). Our results indicated that, contrary to expectations, combinations of different transcriptional control elements affected the level, duration, and onset of gene expression differently in developing zebrafish and goldfish. The major differences in expression of β-actin/CAT (chloramphenicol acetyltransferase) constructs in zebrafish and goldfish were: (1) overall expression was almost 100-fold higher in goldfish than in zebrafish embryos, (2) the first intron had an enchancing effect on gene expression in zebrafish but not in goldfish, and (3) the serum-responsive/CArG-containing regulatory element in the proximal promoter was not always required for maximal CAT activity in goldfish, but was required in zebrafish. These results suggest that in the zebrafish, but not in the goldfish, there may be interactions between motifs in the proximal promoter and the first intron which appear to be required for maximal enhancement of transcription.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Transgenic research 8 (1999), S. 321-334 
    ISSN: 1573-9368
    Keywords: border elements ; position effects ; transgenics ; zebrafish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The variability in expression patterns of transgenes, caused by the influence of neighboring chromatin, is called 'position effect'. Border elements are DNA sequences, which have the ability to alleviate position effects. The abilities of two types of border elements, scs/scs′ from the D. melanogaster 87A7 heat shock locus and the A‐element from the chicken lysozyme gene, to protect transgenes from position effects were quantified in developing zebrafish embryos. The transgenic construct used was FV3CAT, which consists of the carp β‐actin transcriptional regulatory region, the chloramphenicol acetyltransferase (CAT) gene and the 3′‐untranslated region from the Chinook salmon growth hormone gene. FV3CAT constructs flanked by either scs/scs′‐elements or A‐elements were introduced into zebrafish chromosomes and the spatial and temporal expression patterns of the transgenes were quantified in multiple generations of transgenic zebrafish. Levels of transgene expression were uniform in the pre‐differentiated and fully differentiated populations of cells present during embryonic development. Levels of transgene expression were proportional to the numbers of integrated transgenes. Expression of transgenes per cell varied less than two‐fold in different transgenic lines. Both types of border elements were able to prevent the influences of neighboring chromatin on transgene expression through three generations of fish. The results are consistent with the ability of border elements to function with equal efficiencies in the many cell types found in vertebrates. Thus, inclusion of border elements in genetic constructs can provide reliable and reproducible levels of gene expression in multiple lines of fish.
    Type of Medium: Electronic Resource
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