Zebrafish insulin-like growth factor-I receptor: molecular cloning and developmental expression.

The biological actions of the insulin-like growth factors (IGFs) are mediated primarily by the IGF-I receptor (IGF-IR), and the IGF family has been highly conserved throughout vertebrate evolution. In this study we report the isolation of a 3 kb cDNA clone for the zebrafish IGF-IR that includes the complete 3' untranslated region and polyA tail and mapping of the receptor gene to zebrafish linkage group 7. The open reading frame deduced from the cDNA sequence encompasses the juxtamembrane and protein tyrosine kinase portions of the receptor, and is 70 and 67% identical to the corresponding regions of the IGF-IRs of the turbot and Xenopus, respectively. By RT-PCR, zebrafish IGF-IR expression was detected from early blastula to early larval stages of development. Using whole mount in situ hybridization, IGF-IR expression was detected after gastrulation. Expression was evident in most tissues but was particularly evident in the tail, in eye and ear primordia and in the brain.

A "consumer" survey of educational provision for deaf and hard of hearing students.

The researchers report the results of a survey of 140 deaf and hard of hearing students attending integrated or self-contained high school classrooms in the state of New South Wales, Australia. The survey was designed to gather information about educational experiences and preferences for various types of educational placements. There were no gender differences in placement, but there were hearing status differences (81.6% of the students in segregated placements had severe or profound hearing losses, compared to 52.4% of the students in integrated settings). Even though students were aware of the advantages and disadvantages of the different placement options, 80% indicated that they were generally satisfied with their current placement. One implication is that a range of options seems to be more appropriate than a one-size-fits-all model, at least from students' perspectives. The views and preferences of students should be considered when educational provisions are designed for students who are deaf or hard of hearing.

Atlantic salmon HNF-3/forkhead: cDNA sequence, evolution, expression, and functional analysis.

We report the isolation and characterization of a cDNA encoding an HNF-3 family member (as HNF-3) from Atlantic salmon (Salmo salar L). The important functional domains of HNF-3 proteins that have been characterized previously are revealed by segments of high identity along the alignment of the asHNF-3 with winged helix/forkhead amino acid sequences isolated from other species. A comparison of asHNF-3 cDNA and genomic DNA indicated that there were no introns present in the asHNF-3 gene. Expression of asHNF-3 protein in adult salmon tissues was not exclusive to liver but was also present in the pancreas and intestine. An RT-PCR analysis performed on salmon development showed that asHNF3 expression is detectable before gastrulation at the mid blastula transition stage. Functional analysis of the asHNF-3 protein using a characterized HNF-3 consensus binding site demonstrated that the protein can recognize and bind to specific HNF-3 consensus sequences. We also report the identification of a novel HNF3 binding site in the promoter of the Atlantic salmon transferrin gene.

Transcriptional regulation of expression of the rainbow trout albumin gene by estrogen.

Estrogens modulate the expression of many liver-specific genes in oviparous species. For instance, expression of the estrogen receptor and vitellogenin genes is strongly up-regulated by estradiol in rainbow trout liver. Using hepatocyte primary cultures, we demonstrate that trout albumin (Alb) gene is also regulated by this hormone. Indeed, treatment of hepatocytes with 1 microM estradiol led, after 24 h, to a dramatic decrease in Alb mRNA level. To investigate the mechanism of this down-regulation, run-off experiments were performed and mRNA half-lives were determined in the presence and absence of estradiol. The results show that the down-regulation of Alb mRNA expression by estrogens occurs only at the transcriptional level.

Salmon HNF1: cDNA sequence, evolution, tissue specificity and binding to the salmon serum albumin promoter.

cDNA clones coding for the transcription factor HNF1 have been isolated from Atlantic salmon (Salmo salar L.). The 559 amino acid residue long encoded protein shows high conservation, with respect to other species, of the domains necessary for DNA-binding: the HNF1 atypical homeodomain, the POU related sequence and the dimerisation domain. Alignment with rat HNF1 protein reveals that the transcription activation domains ADI and ADIII are relatively conserved in the fish sequence whereas ADII is not. Phylogenetic analysis indicates that higher vertebrate HNF1s and the related variant HNF1s (vHNF1s) are more closely related to each other than any of them is to Salmon HNF1, suggesting that the duplication event from which HNF1 and vHNF1 genes arose occurred after the divergence of the tetrapod and teleost ancestors. Northern blot analysis show a single transcript, of about 2.6 kb, which is not exclusive to liver but is also present in intestine, kidney and spleen. Using polymerase chain reaction (PCR) we have isolated the salmon albumin gene promoter which contains, upstream of the TATA box, a potential binding site for HNF1. The salmon HNF1 protein synthesized by in vitro transcription-translation of the full-length cDNA is able to bind specifically with equivalent affinities to either the rat or salmon albumin promoter.

Cloning and sequencing of the Atlantic salmon (Salmo salar) cytochrome c oxidase subunit III gene (coxIII) and analysis of coxIII expression during parr-smolt transformation.

Smoltification is the process whereby salmon alter their metabolism in preparation for movement from freshwater to seawater. Differential screening of a cDNA library prepared from post-smolt salmon liver mRNA led to the selection of a smoltification-induced sequence. Analysis of this cDNA revealed that it partially encoded subunit III of the enzyme cytochrome c oxidase. The complete coxIII sequence was amplified from salmon genomic DNA using consensus oligonucleotides based on ATPase 6 and tRNA(GLY) sequences from Pacific salmonid species. Cytochrome c oxidase subunit III liver mRNA levels were found to be significantly increased in salmon smolts. Northern blot analysis revealed a coxIII transcript of approximately 750 bp in all salmon tissues tested except blood. The DNA sequence of coxIII employs the mammalian mitochondrial genetic code and is strongly conserved when compared with that of other species.

Sequence analysis of a second cDNA encoding Atlantic salmon (Salmo salar) serum albumin.

Two similar, but distinct, cDNAs for Atlantic salmon serum albumin have been isolated from the same salmon liver. Comparison between the asSA-1 and asSA-2 sequences reveals 1% overall sequence difference.

The salmon gene encoding apolipoprotein A-I: cDNA sequence, tissue expression and evolution.

A cDNA encoding an apolipoprotein (Apo) has been isolated from the Atlantic salmon (Salmo salar) and sequenced. It encodes a peptide of 258 amino acids (aa), including a signal peptide of 18 aa, with 5'- and 3'-untranslated regions of the mRNA of 12 and 329 nucleotides, respectively. The protein has structural features in common with other Apo's of human and avian origin, including conserved sequences in the signal peptide and a series of internal repeats of 22 aa. The sequence has been identified as salmon Apo A-I (sApoA-I), and has 23% aa identity with human ApoA-I. Northern-blot analysis using the sApoA-I cDNA probe against total RNA prepared from several salmon tissues detects the expression of this gene in liver, intestine and muscle. A phylogenetic analysis reveals that the mammalian ApoA-I, ApoA-IV and Apo-E aa sequences are more closely related to each other than any of them are to sApoA-I. This suggests that the duplication events, from which A-I, A-IV and E arose, occurred after the divergence of the tetrapod and teleost ancestors.

Sequence of a cDNA clone encoding an Atlantic salmon ribosomal protein.

We report here the nucleotide sequence of a cDNA clone encoding a salmon (Salmo salar) ribosomal (r) protein. The encoded protein shows 62.3% and 62% similarity with the L14 and L18 r-proteins in Xenopus laevis and rat, respectively.

Atlantic salmon (Salmo salar) serum albumin: cDNA sequence, evolution, and tissue expression.

Atlantic salmon serum albumin is one of the most abundant proteins in salmon liver, representing 1.6% of all clones in a cDNA library made from salmon liver RNA. The DNA from a number of clones was sequenced to reveal an open reading frame of 1,827 bases encoding a 608-amino-acid protein. The sequenced 5' untranslated region is 69 bases long and the 3' untranslated region contains two putative polyadenylation signals and poly(A) tail. Sequence analysis of different clones indicates the presence of a second cDNA for salmon serum albumin. Multiple alignments of salmon serum albumin deduced amino acid sequence with Xenopus laevis, rat, bovine, and human serum albumins shows significant conservation of cysteine residues. The triple domain structure of serum albumin proteins is maintained. Unlike mammalian systems where serum albumin expression appears to be specific to liver only, salmon serum albumin is expressed in muscle also.

Chicken apolipoprotein A-I: cDNA sequence, tissue expression and evolution.

Using an antibody against chicken apolipoprotein (apo) A-I, we identified multiple cDNA clones for the protein in two intestinal cDNA libraries in lambda gt11. The complete nucleotide sequence of chicken apoA-I cDNA was determined. The sequence predicts a mature protein of 240 amino acids, a 6-amino acid propeptide and an 18-amino acid signal peptide. Using a 32P-cDNA probe, we detected the presence of apoA-I mRNA in 21 day old chicken intestine, liver, kidney, spleen, breast muscle and brain. The primary sequence of apoA-I contains numerous tandem repeats of 11 and 22 residues in a manner similar to the mammalian proteins. Our analysis of apoA-I sequences from human, rabbit, dog, rat, and chicken indicates that the rate of amino acid substitution is considerably faster in the rat lineage than in other mammalian lineages.