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  • 1
    Keywords: Konferenzschrift 1994 ; Aquakultur
    Type of Medium: Book
    Pages: IV, 266 S , Ill., graph. Darst., Kt
    Series Statement: European Aquaculture Society special publication 25
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 10 (1971), S. 881-888 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Under aquaculture conditions, European eels (Anguilla anguilla) produce a high percentage of males (80–95%) that normally stop growing at 100–200 g. Females continue to grow to 500–750 g and obtain higher market value. Therefore, increasing the percentage of females in a population would be beneficial to the culture of eels. The present study was carried out in order to examine the effect of oestradiol and phytooestrogens on sex differentiation and growth rate of eels. Juvenile European eels with undifferentiated gonads were fed pellets containing oestradiol-17β (E2) or phytooestrogens for 100–150 days. Feeding E2 resulted in 50–61% increase in body weight compared with the control. Oestradiol-17β and phytooestrogens both elevated significantly the percentage of females in the population. Feeding E2 at 20 mg kg−1 feed resulted in 70% females, while lower concentration of E2 (2 mg kg−1) resulted in only 30% after 100 days (Experiment 1). The same dose given for 150 days (Experiment 2) resulted in 88% females, indicating that both, the concentration and duration of E2 treatments had a significant effect on sex differentiation. Fish fed genistein at 2 mg kg−1 for 100 days, resulted in 55% of females, but at a higher dose of 20 mg kg−1 there were only 15% females. These results demonstrate that phytooestrogens can be used as alternatives to gonadal steroids for sex manipulation in eels, but the optimal concentrations and duration are still to be determined.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Company
    Nature biotechnology 8 (1990), S. 1268-1272 
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Genetic alteration of fish is important for aquatic biotechnology as well as for investigating molecular interactions that occur during vertebrate development. The numerous, large, transparent, and externally fertilized eggs of many fish species make them ideally suitable for genetic manipulation, ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 11 (1993), S. 345-352 
    ISSN: 1573-5168
    Keywords: growth hormone gene ; all-fish genes ; transgenic fish ; cell line transfection ; Sparus aurata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Abstract In order to develop all-fish expression vectors for microinjection into fertilized fish eggs, we have prepared the following constructs: rainbow trout metallothionein a/b and the gilthead seabream growth hormone cDNA (ptMTa-gbsGHcDNA, ptMTb-gsbGHcDNA), carp β-actin gilthead seabream GH cDNA (pcAβ-gsbGHcDNA). The inducible metallothionein promoters a and b were cloned from rainbow trout, and the constitutive promoter β-actin was isolated from carp. The metallothionein promoters were cloned by using the PCR technique. The tMTa contains 430 bp, while the tMTb contains 260 bp (Hong et al. 1992). These two promoters were introduced to pGEM-3Z containing the GH cDNA of Sparus aurata to form ptMTa-gsbGH and ptMTb-gsbGH, respectively. The carp cytoplasmic β-actin gene was chosen as a source for isolating strong constitutive regulatory sequences. One of these regulatory sequences in pUC118 was ligated to GH cDNA of S. aurata to form the pcAβ-gsbGHcDNA. Expression of the constructs containing the metallothionein promoters was tested in fish cell culture and was found to be induced effectively by zinc. The ptMTa gsb-GH cDNA construct was microinjected into fertilized carp eggs, and integration in the genome of carp was detected in the DNA isolated from fins at the age of two months.
    Notes: Résumé Afin de développer des vecteurs d'expression de poisson, entièrement homologues, destinés aux microinjections dans des oeufs fertilisés, les constructions suivantes ont été préparées: promoteurs de la metallothionine, a ou b, de truite arc-en-ciel d'une part, et promoteur de l'actine β de carpe d'autre part, associés à l'ADNc de l'hormone de croissance de daurade royale (ptMTa-gsbGH cDNA, ptMTb-gsbGH cDNA, et pcAβ-gsbGH cDNA). Les promoteurs de la metallothionine ont été clonés en utilisant la technique de la RCP. La tMTa comprend 430 pb. tandis que la tMTb en comprend 260 (Hong et al. 1992). Ces deux promoteurs ont été insérés dans pGEM-3Z qui contenait l'ADNc de GH de Sparus aurata, pour former, respectivement, ptMTa-gsbGH et ptMTb-gsbGH. Le gène de l'actine cytoplasmique β de carpe été choisi comme source d'isolement de séquences régulatrices fortement constitutives. Une de ces séquences régulatrices a été liguée à l'ADNc de GH de S. aurata dans pUC118, pour réaliser la construction pcAβ-gsbGH cDNA. L'expression des constructions contenant les promoteurs de la metallothionine a été tentée dans des cultures de cellules de poisson, où elle a été effectivement induite par le zinc. La construction ptMTa-gsbGH cDNA a été microinjectée dans des oeufs fertilisés de carpe. Son intégration dans le génome de carpe a pu être détectée dans l'ADN isolé à partir de nageoires d'animaux agés de 2 mois.
    Type of Medium: Electronic Resource
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  • 6
    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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  • 7
    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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