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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
    New York, NY : Wiley-Blackwell
    Gamete Research 14 (1986), S. 293-306 
    ISSN: 0148-7280
    Keywords: fertilization ; proteolysis ; nuclear proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spermatogenesis in the male rat involves chemical and physical transformation of chromatin. There is a shift in the chemical composition of rat testicular sperm chromatin containing histones to nucleoprotamines in the mature sperm. Rat protamine contains a high percentage of arginine. The biosynthesis and kinetics of H3-arginine incorporation into rat sperm protamine was at its peak in the testis 2 days after intratesticular injection. The specific activity of protamine in the testis was reduced to 50% 5 days after injection. Specific activity of protamine in the epididymis was maximal at 9 days after injection and remained at a similar level for 12 days. The kinetics of H3-arginine and H3-thymidine in ejaculated sperm were compared. It was found that maximal specific activity of H3-arginine (H3-Arg/No. of sperm) in the spermatozoa was obtained 20-22 days following its intratesticular injection. The peak of H3-thymidine specific activity (H3-thymidine/No. of sperm) was obtained 53-59 days following the injection.H3-Arg labeled sperm were capacitated in vitro and were allowed to penetrate zona free rat eggs in vitro. The disappearance of the label from the sperm head was observed 1-2 hr after penetration. Protamine labeled in vitro with I125 incubated with extracts of freshly ovulated rat eggs shows that protamine could be degraded by the cytoplasmic extract (10-30%). The proteolytic activity is maximal at pH 7.0-8.0. Cytoplasmic extracts from cumulus cells incubated with I125 rat protamine under identical conditions did not show any significant proteolytic activity. Trypsin degradation of rat protamine shows a different pattern of degradation. It is assumed that the H3-labeled protamine in the sperm chromatin is removed and probably degraded early after penetration, making possible the remodeling of the sperm chromatin by embryonic histones.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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