Browsing by Author "Sweeney, Glen E."
Now showing 1 - 10 of 19
Results Per Page
Sort Options
- Analysis of the Sox gene family in the european sea bass (Dicentrarchus labrax)Publication . Galay-Burgos, M.; Llewellyn, Lynda; Mylonas, Constantinos C.; Canario, Adelino V. M.; Zanuy, Silvia; Sweeney, Glen E.Sox (SRY-related genes containing a HMG box) genes encode a family of transcription factors that are involved in a variety of developmental processes including sex determination. Twenty Sox genes are present in the genomes of humans and mice, but far less is known about the Sox gene family in other vertebrate types. We have obtained clones representing the HMG boxes of twelve Sox genes from European sea bass (Dicentrarchus labrax), a fish species whose farming is complicated by a heavily skewed sex ratio, with between 70% and 99% of offspring typically being male. The cloned Sox genes are members of the SoxB, SoxC, SoxE and SoxF groups. Sequence analysis shows that some of the clones represent genes duplicated in sea bass with respect to the mammalian Sox gene family.
- Characterization of a sea bream (Sparus aurata) thyroid hormone receptor-ß clone expressed during embryonic and larval developmentPublication . Nowell, M. A.; Power, Deborah; Canario, Adelino V. M.; Llewellyn, Lynda; Sweeney, Glen E.A clone encoding thyroid hormone receptor-b (TR-b) was isolated from a sea bream (Sparus aurata) ovary cDNA library. Sea bream (sb)TR-b is closely related to its counterparts from other vertebrates and, like them, preferentially binds T3 rather than T4. However, the putative sbTR-b protein contains a nine-amino-acid insert that is also present in the corresponding proteins from flounder and salmon but absent in TR-bs from zebrafish and terrestrial vertebrates. Semiquantitative RT–PCR analysis showed that sbTR-b transcripts begin to accumulate during gastrulation and increase markedly in quantity up to the period around hatch (ca. 40 h postfertilization) before declining slightly. In adult tissues, TR-b mRNA was present in approximately equal quantities in heart, intestine, brain, kidney, skeletal muscle, liver, and gill. The significance of the relatively strong expression of TR-b during sea bream embryogenesis is discussed.
- Cloning and characterisation of a fish aldolase B genePublication . Llewellyn, Lynda; Ramsurn, Vimi P.; Sweeney, Glen E.; Wigham, Trevor; Santos, Cecilia; Power, DeborahA full length cDNA clone representing an aldolase mRNA was isolated from a sea bream (Sparus aurutu) liver cDNA library. Sequencing of this clone revealed it to encode a 364 amino acid protein with 74% amino acid identity to human aldolase B and slightly lower similarity to human aldolase A and C. In view of the sequence data and of Northern blot analysis showing strong expression of a 1.6 kb transcript in liver it was concluded that the cloned gene represents aldolase B. This clone represents the first aldolase gene to be sequenced from any fish species thus providing new data on the evolution of the vertebrate aldolase gene family.
- Cloning and expression of an elongation factor-1α in sea bream ( Sparus aurata ) larvae and adult tissuePublication . Nowell, M. A.; Power, Deborah; Guerreiro, P. M.; Llewellyn, Lynda; Ramsurn, Vimi P.; Wigham, Trevor; Sweeney, Glen E.A clone encoding the polypeptide elongation factor EF-1a was isolated from a complementary DNA library prepared from sea bream (Spartus aurata) larvae 1 to 10 days after hatching. The deduced amino acid sequence is between 82% and 95% similar to EF-1a in other animal species. EF-1a messenger RNA is present at low abundance in sea bream embryos prior to gastrulation, but at around 15 hours postfertilization, there is a 10-fold increase in transcript levels. This increase presumably reflects midblastula transition in this species. In adult sea bream, EF-1a appeared to have a relatively uniform distribution across all the tissues analyzed.
- Cloning and sequencing of a full-length sea bream (Sparus aurata) beta-actin cDNAPublication . Santos, Cecilia; Power, Deborah; Kille, Peter; Llewellyn, Lynda; Ramsurn, Vimi P.; Wigham, Trevor; Sweeney, Glen E.A full-length cDNA clone encoding beta-actin (b-actin) was isolated from a sea bream (Sparus aurata) liver cDNA library. Sequencing of this clone reveals an open reading frame encoding a 375 amino acid protein that shares a high degree of conservation to other known actins. The sea breamb-actin sequence showed 98% identity to carp and human b-actin and 95% and 94% identity to sea squirt and Dictyostelium cytoplasmic actins, respectively.
- Cloning, characterisation and expression of the apolipoprotein A-I gene in the sea bream (Sparus aurata)Publication . Llewellyn, Lynda; Ramsurn, Vimi P.; Wigham, Trevor; Sweeney, Glen E.; Power, DeborahA full length cDNA clone representing apolipoprotein A-I was isolated from a sea bream (Sparus aurata) liver library. The clone encodes a 261 amino acid protein which shows highest amino acid identity (38%) with salmon apolipoprotein A-I. Northern blot analysis showed strong expression of a 1.4 kb transcript in liver with lower expression in intestine. Expression of apolipoprotein A-I in intestine was markedly reduced by treatment with triiodothyronine (T3). ß 1998 Elsevier Science B.V. All rights reserved.
- Coordination of deiodinase and thyroid hormone receptor expression during the larval to juvenile transition in sea bream (Sparus aurata, Linnaeus)Publication . Campinho, Marco António; Galay-Burgos, M.; Sweeney, Glen E.; Power, DeborahTo test the hypothesis that THs play an important role in the larval to juvenile transition in the marine teleost model, sea bream (Sparus auratus), key elements of the thyroid axis were analysed during development. Specific RT-PCR and Taqman quantitative RT-PCR were established and used to measure sea bream iodothyronine deiodinases and thyroid hormone receptor (TR) genes, respectively. Expression of deiodinases genes (D1 and D2) which encode enzymes producing T3, TRs and T4 levels start to increase at 20–30 days post-hatch (dph; beginning of metamorphosis), peak at about 45 dph (climax) and decline to early larval levels after 90–100 dph (end of metamorphosis) when fish are fully formed juveniles. The profile of these different TH elements during sea bream development is strikingly similar to that observed during the TH driven metamorphosis of flatfish and suggests that THs play an analogous role in the larval to juvenile transition in this species and probably also in other pelagic teleosts. However, the effect of T3 treatment on deiodinases and TR transcript abundance in sea bream is not as clear cut as in larval flatfish and tadpoles indicating divergence in the responsiveness of TH axis elements and highlighting the need for further studies of this axis during development of fish.
- Expression of thyroid hormone receptor during early development of the sea bream (Sparus aurata)Publication . Llewellyn, Lynda; Ramsurn, Vimi P.; Sweeney, Glen E.; Wigham, Trevor; Power, DeborahThe thyroid hormones thyroxine (T4) and triiodothyronine (T3) are crucial to many aspects of vertebrate growth, development, and metabolism. They act through intracellular receptor proteins which act directly on target genes. Although the role of thyroid hormones in fish, especially in early development, is not well understood, thyroid hormones are passed to eggs by broodfish during spawning and are implicated in fish development.1,2 Sea bream (Sparus aurata) aquaculture has grown rapidly in importance in the European Community, particularly in southern Portugal. However, its further development is hindered by the high larval mortality rate and incidence of malformations. This work investigates the significance of thyroid hormones in sea bream development by cloning the thyroid hormone receptor (TR) and analyzing its expression during larval development.
- Growth hormone profiles and development of somatotrophs in Atlantic Halibut LarvaePublication . Einarsdóttir, Ingibjörg E.; Sweeney, Glen E.; Power, Deborah; Kristjánsson, Birgir A.; Björnsson, Björn ThrandurThe Atlantic halibut is the largest flatfish species, and as other flatfish, has a complicated larval development. The pelagic larvae hatch after about two weeks and feeding starts six weeks later. After three to four months, they start to undergo metamorphosis. Following major changes in body shape, including the migration of the left to the right side, the larvae settle as bottom dwelling. In Atlantic halibut aquaculture, the larval rearing is a critical rearing stage, with high incidence of mortality and abnormal development.
- Identification and analysis of teleost slow muscle troponin T (sTnT) and intronless TnT genesPublication . Campinho, Marco António; Power, Deborah; Sweeney, Glen E.In the present study cDNA clones representing two slow skeletal muscle troponin T genes (sTnT1sb and sTnT2sb) in the sea bream (Sparus auratus), an important aquaculture species, were isolated and characterised. A third, intronless, TnT gene (iTnTsb), which is an apparent orthologue of a previously described zebrafish TnT, was also isolated. In adult sea bream sTnT expression was restricted to red muscle and, using northern blotting, a single low abundance transcript was identified for sTnT1sb (1260 nucleotides) and a single high abundance transcript was identified for sTnT2sb (1000 nucleotides). In contrast, iTnTsb is predominantly expressed in adult fast muscle. All three TnT genes are also expressed during larval development. Phylogenetic analysis of sea bream sTnT proteins to identify maximum parsimony showed that iTnTsb, sTnT1sb and sTnT2sb each cluster in independent groups. sTnT1sb clustered with other vertebrate sTnTs, while sTnT2 clustered with a group of fish specific sequences (from Fugu rubripes, Oryzia latipes and Salmo trutta). The teleost sTnT2 and iTnT each constitute new, apparently teleost specific, TnT groups. Analysis of the corresponding Fugu scaffold indicates that sTnT2sb is encoded by a gene with twelve exons. The two sTnT cDNAs isolated in sea bream probably arose by duplication of an ancestral gene, and iTnT by reverse transcription. It remains to be established if the encoded proteins have different structural and mechanistic roles in fish muscle.