The complete nucleotide sequence of the growth-hormone gene from Atlantic salmon (Salmo salar)

Gene structure and functional characterization of growth hormone in dogfish, Squalus acanthias

Dogfish (Squalus acanthias) growth hormone (GH) was identified by cDNA cloning and protein purification from the pituitary gland. Dogfish GH cDNA encoded a prehormone of 210 amino acids (aa). Sequence analysis of purified GH revealed that the prehormone is composed of a signal peptide of 27 aa and a mature protein of 183 aa. Dogfish GH showed 94% sequence identity with blue shark GH, and also showed 37-66%, 26%, and 48-67% sequence identity with GH from osteichtyes, an agnathan, and tetrapods. The site of production was identified through immunocytochemistry to be cells of the proximal pars distalis of the pituitary gland. Dogfish GH stimulates both insulin-like growth factor-I and II mRNA levels in dogfish liver in vitro. The dogfish GH gene consisted of five exons and four introns, the same as in lamprey, teleosts such as cypriniforms and siluriforms, and tetrapods. The 5'-flanking region within 1082 bp of the transcription start site contained consensus sequences for the TATA box, Pit-1/GHF-1, CRE, TRE, and ERE. These results show that the endocrine mechanism for growth stimulation by the GH-IGF axis was established at an early stage of vertebrate evolution, and that the 5-exon-type gene organization might reflect the structure of the ancestral gene for the GH gene family.

The growth hormone-encoding gene isolated and characterized from Labeo rohita Hamilton is expressed in CHO cells under the control of constitutive promoters in 'autotransgene' constructs

The growth hormone (GH) gene along with its regulatory sequences has been isolated from the blood and pituitary gland of Labeo rohita. This GH gene is approximately 2.8 kb long and consists of five exons and four introns of varying sizes with AG/TA in its exon-intron junctions. The promoter has a single cyclic AMP response unit (CRE) element, TATA, CAT and several Pit 1 binding sequences. The 1169-bp gene transcript starts 54 bp upstream of the ATG initiation codon and has two polyadenylation signals, ATTAAA, after the TAG stop codon. The mature mRNA has the poly (A) tail inserted 16 bp downstream of the second polyadenylation signal. Four chimeric 'autotransgenes' were constructed having either histone 3 or beta-actin promoter and cDNA or the total GH gene. The functionality of the individual components of the autotransgene was determined in the Chinese hamster ovary (CHO) cells by transfection experiments. Based on the results, the transcription of the GH gene is initiated at the transcription start signal of the respective promoters and terminates at the 3' regulatory sequence of the GH gene. Expression of GH in CHO cells shows that the fish promoters are active, the splicing signal is recognized, and the mRNA produced is stable and translated. The GH protein produced is effectively translocated and secreted into the medium. These results indicate the usefulness of CHO cells in determining the property of individual components of autotransgenes constructed from L. rohita and overall functional commonality between fish and mammal.

Genomic structure of the sea lamprey growth hormone-encoding gene

Growth hormone (GH) belongs to a family of pituitary hormones together with prolactin and somatolactin. In our previous study, GH and its cDNA were identified in the pituitary gland of the sea lamprey, Petromyzon marinus, an extant representative of the most ancient class of vertebrates, and isolated GH stimulated expression of insulin-like growth factor in the liver. The evidence suggests that GH is the ancestral hormone in the molecular evolution of the GH/PRL/SL family and that the endocrine mechanism for growth stimulation was established at an early stage in the evolution of vertebrates. To further understand the molecular evolution of the GH/PRL/SL gene family, we report the genomic structure of sea lamprey GH including its 5'-flanking region, being cloned by PCR using specific primers prepared from its cDNA. The sea lamprey GH gene consists of 13,604 bp, making it the largest of all the GH genes. The 5'-flanking region within 697 bp contains consensus sequences for a TATA box, two Pit-1/GHF-1, three TRE, and a CRE. The sea lamprey GH gene consists of five exons and four introns, the same as in mammals, birds, and teleosts such as cypriniforms and siluriforms with the exception of some teleosts such as salmoniforms, percififorms, and tetradontiforms, in which there is an additional intron in the 5th exon. The 5-exon-type gene organization might reflect the structure of the ancestral gene for the GH/PRL/SL gene family.

The dawn and evolution of hormones in the adenohypophysis

The adenohypophysial hormones have been believed to have evolved from several ancestral genes by duplication followed by evolutionary divergence. To understand the origin and evolution of the endocrine systems in vertebrates, we have characterized adenohypophysial hormones in an agnathan, the sea lamprey Petromyzon marinus. In gnathostomes, adrenocorticotropin (ACTH) and melanotropin (MSH) together with beta-endorphins (beta-END) are encoded in a single gene, designated as proopiomelanocortin (POMC), however in sea lamprey, ACTH and MSH are encoded in two distinct genes, proopoicortin (POC) gene and proopiomelanotropin (POM) gene, respectively. The POC and POM genes are expressed specifically in the rostral pars distalis (RPD) and the pars intermedia (PI), respectively. Consequently, the final products from both tissues are the same in all vertebrates, i.e., ACTH from the PD and MSH from the PI. The POMC gene might have been established in the early stages of invertebrate evolution by internal gene duplication of the MSH domains. The ancestral gene might be then inherited in lobe-finned fish and tetrapods, while internal duplication and deletion of MSH domains as well as duplication of whole POMC gene took place in lamprey and gnathostome fish. Sea lamprey growth hormone (GH) is expressed in the cells of the dorsal half of the proximal pars distalis (PPD) and stimulates the expression of an insulin-like growth factor (IGF) gene in the liver as in other vertebrates. Its gene consists of 5 exons and 4 introns spanning 13.6 kb, which is the largest gene among known GH genes. GH appears to be the only member of the GH family in the sea lamprey, which suggests that GH is the ancestral hormone of the GH family that originated first in the molecular evolution of the GH family in vertebrates and later, probably during the early evolution of gnathostomes. The other member of the gene family, PRL and SL, appeared by gene duplication. A beta-chain cDNA belonging to the gonadotropin (GTH) and thyrotropin (TSH) family was cloned. It is expressed in cells of the ventral half of PPD. Since the expression of this gene is stimulated by lamprey gonadotropin-releasing hormone, it was assigned to be a GTHbeta. This GTHbeta is far removed from beta-subunits of LH, FSH, and TSH in an unrooted tree derived from phylogenetic analysis, and takes a position as an out group, suggesting that lampreys have a single GTH gene, which duplicated after the agnathans and prior to the evolution of gnathostomes to give rise to LH and FSH.

Evolution of duplicated growth hormone genes in autotetraploid salmonid fishes

A defining character of the piscine family Salmonidae is autotetraploidy resulting from a genome-doubling event some 25-100 million years ago. Initially, duplicated genes may have undergone concerted evolution and tetrasomic inheritance. Homeologous chromosomes eventually diverged and the resulting reduction in recombination and gene conversion between paralogous genes allowed the re-establishment of disomic inheritance. Among extant salmonine fishes (e.g. salmon, trout, char) the growth hormone (GH) gene is generally represented by two functional paralogs, GH1 and GH2. Sequence analyses of salmonid GH genes from species of subfamilies Coregoninae (whitefish, ciscos) and Salmoninae were used to examine the evolutionary history of the duplicated GH genes. Two divergent GH gene paralogs were also identified in Coregoninae, but they were not assignable to the GH1 and GH2 categories. The average sequence divergence between the coregonine GH genes was more than twofold lower than the corresponding divergence between the salmonine GH1 and GH2. Phylogenetic analysis of the coregonine GH paralogs did not resolve their relationship to the salmonine paralogs. These findings suggest that disomic inheritance of two GH genes was established by different mechanisms in these two subfamilies.

Cloning, sequencing and expression of cDNA encoding growth hormone from Indian catfish (Heteropneustes fossilis)

A tissue-specific cDNA library was constructed using polyA+ RNA from pituitary glands of the Indian catfish Heteropneustes fossilis (Bloch) and a cDNA clone encoding growth hormone (GH) was isolated. Using polymerase chain reaction (PCR) primers representing the conserved regions of fish GH sequences the 3' region of catfish GH cDNA (540 bp) was cloned by random amplification of cDNA ends and the clone was used as a probe to isolate recombinant phages carrying the full-length cDNA sequence. The full-length cDNA clone is 1132 bp in length, coding for an open reading frame (ORF) of 603 bp; the reading frame encodes a putative polypeptide of 200 amino acids including the signal sequence of 22 amino acids. The 5' and 3' untranslated regions of the cDNA are 58 bp and 456 bp long, respectively. The predicted amino acid sequence of H. fossils GH shared 98% homology with other catfishes. Mature GH protein was efficiently expressed in bacterial and zebrafish systems using appropriate expression vectors. The successful expression of the cloned GH cDNA of catfish confirms the functional viability of the clone.

Structure and tissue distribution of prolactin receptor mRNA in Japanese flounder (Paralichtys olivaceus): conserved and preferential expression in osmoregulatory organs

In diadromous and euryhaline teleosts, it has been established that prolactin (PRL) is a major hormone regulating the maintenance of water and electrolyte homeostasis by acting on its receptor (PRLR) expressed in the osmoregulatory organs. To investigate the major physiological role of PRL in a marine teleost, cDNA for the Japanese flounder (Paralichtys olivaceus) prolactin receptor (fPRLR) has been cloned and characterized. The predicted fPRLR is composed of 636 amino acids conserving common structural features, such as the WSXWS motif and box 1, that are observed in the members of the cytokine receptor superfamily. By Northern blot analysis, 3.5-kb transcripts for fPRLR were clearly detected in the gill, kidney, and intestine. By RNase protection assay, similarly high levels of mRNA expression were detected in these osmoregulatory organs and lower expression levels were seen in the brain for both males and females. Interestingly, a distinct expression level of fPRLR mRNA was observed in the testis, but not in the ovary. The present results suggest that PRL may play an important role in the control of water and electrolyte balance through PRLR expressed in the osmoregulatory organs in the marine teleost the Japanese flounder as well as in other teleosts. Furthermore, PRL may differentially regulate gonadal functions in males and females of Japanese flounder.

Genomic structure and sequence of the gilthead seabream (Sparus aurata) growth hormone-encoding gene: identification of minisatellite polymorphism in intron I

The growth hormone (GH) gene of the gilthead seabream (Sparus aurata) (saGH) has been cloned, sequenced, and characterized. The saGH gene spans approximately 4.3 kb and consists of six exons and five introns, as found for all cloned teleost GH genes with the exception of carps and catfish. The first and third introns contain long stretches of repetitive tandem repeats. The second intron, which is unusually long compared with that in other teleosts (and other vertebrates) spans 1747 nucleotides (nt) and contains several inverted repeats. Intron-targeted polymerase chain reaction (PCR) analysis identified length polymorphism of the first intron. Sequence analysis of four variants (405, 424, 636, and 720 nt) out of many variants found revealed that the variation in length is due to differences in the number of repeat monomers (17-mer or 15-mer) as well as minor changes in their length. This repeat unit contains the consensus half-site motif of the thyroid hormone response element (TRE) and estrogen response element (ERE). Polymorphism was found also in the third intron. This is the first report of such high polymorphism of the first intron of GH gene in a vertebrate.

Transfer of growth hormone (GH) transgenes into Arctic charr. (Salvelinus alpinus L.) I. Growth response to various GH constructs

Four constructs containing salmonid growth hormone (GH) genes were transferred to Arctic charr (Salvelinus alpinus L.). Cytomegalovirus (CMV) and piscine metallothionein B (OnMT) and histone 3 (OnH3) promoters connected to sockeye salmon growth hormone 1 gene (OnGH1) were used for ectopic expression, and Atlantic salmon growth hormone 2 gene with 5'flanking region (SsGH2) was tested for pituitary-specific expression. Charr carrying the OnGH1 constructs showed a dramatic increase in growth rate. The 10-month old transformed fish were 14-fold heavier than control siblings. The ability of the CMVGH1 construct to promote growth was greater than that obtained in fish with piscine promoters. Analysis of individual growth curves of charr carrying the OnH3GH1 transgene indicated a stable ratio of specific growth rates in transformed and control fish regardless of fish size. No alteration in growth performance was found in fish carrying the SsGH2 transgene. There was evidence that the transformed rainbow trout (Oncorhynchus mykiss) were unable to produce SsGH2 mRNA in their pituitary glands. The presence of the transgene in various tissues was examined in trout to evaluate the reliability of one-tissue sampling.

Regulatory regions in the promoter and third intron of the growth hormone gene in rainbow trout, Oncorhynchus mykiss walbaum

The mechanisms involved in the transcriptional regulation of the rainbow trout (Oncorhynchus mykiss) growth hormone (tGH) gene have been investigated. Transient transfection assays, using deletion mutants of the tGH promoter, demonstrated that the -226/+24 5'-flanking region, bearing three binding sites for the pituitary-specific transcription factor GHF1/Pit1 and a cAMP-response element, is necessary and sufficient to confer strong tissue-specific and cAMP-stimulated expression to a luciferase reporter gene. This region is also upregulated by the synthetic glucocorticoid dexamethasone (DEX), the combined effects of cAMP, and DEX being synergistic. Footprinting and gel shift assays revealed that GHF1 binds to a recognition element in the third intron of the tGH gene, suggesting that GHF1 can affect the expression of this gene by interacting with response elements in the transcription unit. These results may be exploited to design tGH gene constructs for the production of autotransgenic fish, in which the expression of the isospecific transgene driven by a constitutive proximal promoter is specifically targeted to the pituitary and physiologically controlled.

Structure and functional analysis of a tilapia (Oreochromis mossambicus) growth hormone gene: activation and repression by pituitary transcription factor Pit-1

A gene encoding the Tilapia mossambica (Oreochromis mossambicus) growth hormone (tiGH) was isolated and sequenced. The gene spans 5.6 kb, including 3.7 kb of 5' and 0.2 kb of 3' flanking sequences and a 1.7-kb transcription unit comprised of six exons and five introns. The gene and the 5' flanking region contain several potential binding sites for Pit-1, a key transcription activator of mammalian GH genes. One of these (-57/-42) is highly conserved in fish GH genes. It activates transcription in pituitary cells and binds Pit-1. Transfection of luciferase reporter plasmids containing either the -3602/+19 tiGH sequence or one of its 5' deletion mutants (-2863/, -1292/, and -463/+19) resulted in strong activity in Pit-1-producing rat pituitary GC cells. A dose-dependent activation of the tiGH promoter was achieved in nonpituitary fish EPC and monkey COS cells cotransfected with a rat Pit-1 expression vector, demonstrating the crucial role played by Pit-1 as an activator of the tiGH gene. Fusion of the tiGH promoter with the beta-galactosidase gene led to transient expression specifically in the nervous system of microinjected zebrafish embryos. The activity of the tiGH promoter in GC and EPC cells was strongly repressed by extending its 3' end from +19 to +40, a sequence in which a Pit-1-binding site was identified using gel retardation assays. Point mutations of the site that suppressed Pit-1 binding in vitro restored full tiGH promoter activity. Thus, a Pit-1-binding site located in the 5' untranslated region mediates Pit-1-dependent repression of the tiGH gene.

Characterization of rainbow trout (Oncorhynchus mykiss) growth hormone 1 gene and the promoter region of growth hormone 2 gene

Studies by Agellon et al. (Mol. Reprod. Dev. 1, 11-17) showed the presence of two growth hormone (rtGH1 and rtGH2) mRNA species in pituitary glands of adult rainbow trout (Oncorhynchus mykiss). In this study, we have detected rtGH1 and rtGH2 mRNAs in pituitary glands of rainbow trout from fry to 2 years of age. The level of rtGH1 mRNA is notably higher than that of rtGH2 mRNA in 10-day-old fry and 2-year-old females. These results suggest differential expression of rtGH1 and rtGH2 genes in different sexes and developmental stages. As a step toward elucidating the mechanism of differential expression of both GH genes, DNA fragments encoding rtGH1 gene and the promoter/regulatory region of rtGH2 gene were isolated and characterized. Rainbow trout GH genes span approximately 4.5 kb and are composed of six exons and five introns. The 5'-flanking region of both genes contain consensus sequences for TATA boxes and several Pit-1 binding sequences. Consensus sequences related to the cAMP response element, thyroid hormone response element, retinoic acid response element, estrogen response element (ERE), and glucocorticoid response element are present not only in the 5'-flanking region, but also in introns and exons in rtGH1 gene. These hormone response elements, except ERE, are also present in rtGH2 gene.

Genomic structure and sequence of the pufferfish (Fugu rubripes) growth hormone-encoding gene: a comparative analysis of teleost growth hormone genes

A nested polymerase chain reaction (PCR) technique for amplifying a fragment of the gene (GH) encoding teleost growth hormone has been developed. Using this technique, a fragment of the pufferfish, Fugu rubripes and Arothron maculatus, dwarf gourami, Colisa lalia; guppy, Poecilia reticulata; and goldfish, Carassius auratus GH genes were cloned. The Fugu rubripes (Fugu) gene fragment was used to isolate the GH gene from a Fugu genomic library. The complete nucleotide sequence of a 8.5-kb SacI genomic fragment containing the Fugu GH gene has been determined. The GH gene spans 2.5 kb from the first codon to polyadenylation signal, and contains six exons and five introns similar to the GH genes of salmonids, tilapia, barramundi, flounder and yellowtail. The GH introns contain microsatellite and satellite sequences. The microsatellites found in the fifth intron of the GH gene are also present in the corresponding introns of tilapia, barramundi and flounder GH genes. Southern analysis revealed that the GH gene is a single-copy gene in the Fugu. The promoter region of the Fugu GH gene contains conserved sequences that are likely to be involved in the pituitary-specific expression of the gene. A phylogenetic tree of nucleotide (nt) sequences of all known teleost GH genes has been inferred using the distance matrix method. The topology of this tree reflects the major phylogenetic groupings of teleosts. The intron patterns and repetitive sequences of GH genes can serve as useful natural markers for the classification and phylogenetic studies of teleosts.

Sequence of the flounder (Paralichthys olivaceus) growth hormone-encoding gene and its promoter region

The flounder (Paralichthys olivaceus) growth hormone (GH)-encoding gene (fGH) and its promoter region were cloned and sequenced following amplification of genomic DNA by the polymerase chain reaction. The fGH gene is 2.1-kb long and consists of six exons and five introns. In the 5'-flanking region of the determined transcription start point, a potential TATA box is located at -24, and Pit-1/GHF-1-binding site candidates are located in the -70 to -53 and -133 to -141 regions.

Cloning of the barramundi growth hormone-encoding gene: a comparative analysis of higher and lower vertebrate GH genes

In this work the growth hormone-encoding gene (GH) from the fish barramundi (Lates calcarifer) was characterized by nucleotide (nt) sequence analysis and comparative studies on higher and lower vertebrate GH were performed. The barramundi GH contains six exons and five introns. A putative transcription start point 21 nt downstream from a potential TATAAA box was determined, with a modified primary transcript size of 1615 nt predicted. cis-Acting elements potentially important for transcriptional regulation at the basal, hormone-responsive and pituitary gland-specific levels were identified. Several microsatellite and minisatellite repetitive sequences were shown to be present within noncoding portions of this gene. Repeat sequences similar to the deca- and undeca-minisatellites of the barramundi GH were observed in the corresponding introns of the tilapia, but not other teleost GH. Comparative studies on the Osteichthyes, Mammalia and Aves vertebrate class GH promoters suggested that the TATAAA box was the only conserved region between these sequences. Conserved sequences, however, were identified within the GH promoters of different species from the Osteichthyes or Mammalia classes. The Osteichthyes A + T-rich sequence (consensus GATRMATYWAAWCA, where R = A or G; M = A or C, Y = C or T and W = A or T) is the only conserved region identified between teleost GH promoters, and is most likely involved in the pituitary gland-specific expression of these genes.

Application of heteroduplex analysis for detecting variation within the growth hormone 2 gene in Salmo trutta L. (brown trout)

A new method to detect variation at a single copy nuclear gene in brown trout, Salmo trutta L., is provided. The technique entails (i) selective gene amplification by the polymerase chain reaction (PCR), (ii) digestion of amplification products by restriction endonucleases to obtain fragments of suitable size, (iii) hybridization with heterologous DNA followed by denaturation and reannealing to obtain heteroduplex molecules, and (iv) screening for variation in polyacrylamide gels. Variation was studied within a growth hormone 2 gene 1489 bp segment and polymorphism was detected in two HinfI-digested fragments. Formation of different heteroduplex patterns in experimental mixtures of digested amplification products from brown trout and Atlantic salmon, Salmo salar L., allowed us to determine the genotype of the brown trout. Polymorphism was observed in four out of six studied populations.

Production of a biologically active recombinant teleostean growth hormone in E. coli cells

We have isolated and characterized several recombinant lambda phage clones carrying growth hormone (GH) cDNA of striped bass (Morone saxatilis). Nucleotide sequence and the predicted amino acid sequence of sbGH was determined from a recombinant clone carrying the longest cDNA insert. The sbGH cDNA encodes a pre-hormone of 204 amino acid residues. Comparison of the predicted amino acid sequence of sbGH with those of other vertebrates revealed different degrees of sequence identity: approximately 98% with European sea bass; 90% with bluefin tuna; bonito and red seabream; 71% with winter flounder; 64% with salmonids; 55% with carp; and 38% with human. Expression of the mature sbGH cDNA (without the signal peptide sequence) in E. coli cells under regulation of the lambda phage PL promoter produced a polypeptide of 20 kDa. Following renaturation, this recombinant hormone was shown to be biologically active in a radioreceptor competition binding assay and in the induction of hepatic insulin-like growth factor I (IGF-I) mRNA synthesis in vivo.

Cloning of the sole (Solea senegalensis) growth hormone-encoding cDNA

We report here the complete nucleotide (nt) sequence of a cDNA clone encoding Solea senegalensis growth hormone (sGH) isolated from an expression library prepared from sole pituitary gland poly(A)+RNA. The library was screened using a flounder GH cDNA. The cDNA sequence containing an insert of 769 nt was found to encode a polypeptide of 203 amino acids (aa), including a signal peptide of 17 aa. The 5'- and 3'-untranslated regions of the message are 17 and 119-nt long, respectively. Northern blot hybridization detected a 0.9-kb RNA species. The sGH cDNA sequence shows homologies of 80.9, 76.9, 73.8 and 64.2% with the GH of tuna, gilthead seabream, flounder and rainbow trout.

Genomic structure of growth hormone genes in chinook salmon (Oncorhynchus tshawytscha): presence of two functional genes, GH-I and GH-II, and a male-specific pseudogene, GH-psi

Two chinook salmon (Oncorhynchus tshawytscha) growth hormone genes (a functional GH-I gene and a pseudogene, GH-psi) were isolated and characterized. The GH-I gene sequence consists of 1.9 kb of 5'-flanking sequence, 4.1 kb of transcribed region, and 64 bp of 3'-flanking sequence, and contains 6 exons and 5 introns. The pseudogene, GH-psi, spanning 4.1 kb, has a similar structure as the GH-I gene. However, it has one wrong splicing sequence at the intron 1/exon 2 junction, one premature termination codon in exon 5, and a deletion in the last half of exon 5 and the first part of intron 5. In addition to GH-I gene and GH-psi, a third GH gene, GH-II, was identified by the polymerase chain reaction (PCR) and subsequently shown to be the second functional GH-II gene. To study the linkage arrangement of these three GH genes, 50 unrelated chinook salmon (25 males and 25 females) and one chinook salmon family were analyzed by PCR. The results showed that GH-psi exists only in males and that it segregates from father to sons. These results suggest that GH-psi is sex specific and probably resides on the Y chromosome. Together these results indicate that there are three GH genes in the genome of male chinook salmon, and only two GH genes in the females. The extra GH gene in the male is, however, a pseudogene.

Sequence of the growth hormone (GH) gene from the silver carp (Hypophthalmichthys molitrix) and evolution of GH genes in vertebrates

The silver carp (Hypophthalmichthys molitrix) growth hormone (GH) gene was isolated and sequenced following amplification from genomic DNA by the polymerase chain reaction. The gene spans a region of approx. 2.5 kb nucleotides (nt) and consists of five exons. The sequence predicts a polypeptide of 210 amino acids (aa) including a putative signal peptide of 22 hydrophobic aa residues. The arrangement of exons and introns is identical to the GH genes of common carp, grass carp, and very similar to mammals and birds, but quite different from that for the GH genes of tilapia and salmonids. The silver carp GH gene shares a high homology at the nt and aa levels with those of grass carp (95.3% nt, 99.5% aa) and of common carp (81% nt, 95.7% aa).

Molecular cloning and expression of yellowfin porgy (Acanthopagrus latus houttuyn) growth hormone cDNA

1. The growth hormone cDNA of yellowfin porgy (ypGH cDNA) consisted of 915 base pairs. 2. The deduced amino acid (aa) sequence showed that the pre-GH comprised 204 residues, of which the first 17 residues formed a signal peptide. 3. Comparison of aa sequence of ypGH to seabream, tuna, rainbow trout and chum salmon showed that ypGH shared 95.1, 94.1, 65.3 and 62.4% homology with these species, respectively. 4. By expressing the ypGH cDNA in E. coli, a polypeptide around 23 kilodaltons (kDa) was found which was immunoreactive to GH antibody.

Sequence analysis suggests a recent duplication of the growth hormone-encoding gene in Tilapia nilotica

The sequence of two growth hormone(GH)-encoding genes from tilapia fish (Tilapia nilotica) is reported. Our data indicate that the presence of two GH in the tilapia genome is a consequence of a relatively recent duplication event. The two genes are highly homologous, having a similar intron (five)/exon (six) arrangement, and both encode an identical polypeptide. Sequence similarity extends up to bp -628 upstream to the transcription start point, after which the sequences of the two genes are not related to each other. The presence of two GH in the tilapia genome is supported both by the nucleotide sequence and by genomic DNA blot hybridization analysis. Tilapias, like salmonids, contain an extra intron compared with the mammalian GH structure. We suggest that within the superorder Teleostei, the insertion of intron 5 into GH took place after the evolutionary separation of Cyprinoidea, but before Isospondyli (salmonids) and Acanthopterygii (tilapias) were separated. Thus, the additional intron which is probably present in many teleost fish GH may provide an excellent natural marker for evolution and classification studies.

Structure of the tilapia (Oreochromis mossambicus) prolactin I gene

The tilapia (Oreochromis mossambicus) prolactin-I (PRL-I) gene has been cloned and sequenced. Its transcript (3,677 bases long) begins with a guanine and is organized in five exons and four introns like the other known prolactin genes. Analysis of the 1,555-bp 5'-flanking region suggests that pituitary-specific expression of the gene could be regulated through a trans-factor related to the mammalian pituitary-specific factor Pit-1. Two potential binding sites for such a factor were found in the first intron, suggesting a possible regulatory role for this region. Moreover, two potential Z-DNA regions are located at positions -837 to -812 and -246 to -179 from the transcription start site. These two regions could play an important role in the regulation of PRL gene expression.

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.

Primary-structural and evolutionary analyses of the growth-hormone gene from grass carp (Ctenopharyngodon idellus)

The growth-hormone (GH) gene of grass carp, one of the fastest-growing species of farmed fish, was isolated and the DNA sequenced. Only one GH gene is found in this species. This gene, which is 2.5 kb in length, has five exons and four introns, in common with all of the mammalian and the recently published common-carp GH genes. In the course of vertebrate evolution, the total lengths of the intron and the non-coding region of exon 5 of the GH gene have been shortened by 40-70%, whereas the encoding exons of the gene have been slightly increased. The more closely related species exhibit the closest sequence similarity in their GH genes. For example, the similarity of the exons is 84.1-93.2% between grass carp and common carp (within the same family of Syprinedae), 43.5-82.1% between grass carp and rainbow trout (in different orders of Teleostei) and 45.8-58.6% between grass carp and rat (in different grades of Vertebrata). In addition, similar DNA domains, such as thyroid-hormone-receptor-complex-binding site and cell-type-specific cis elements involved in regulation of expression of rat and human GH genes, have been localized in the corresponding regions of the grass-carp GH gene.

Growth enhancement in transgenic Atlantic salmon by the use of an "all fish" chimeric growth hormone gene construct

We have developed an "all fish" growth hormone (GH) chimeric gene construct by using an antifreeze protein gene (AFP) promoter from ocean pout linked to a chinook salmon GH cDNA clone. After microinjection into fertilized, nonactivated Atlantic salmon eggs via the micropyle, transgenic Atlantic salmon were generated. The presence of the transgene was detected by polymerase chain reaction (PCR) using specific oligonucleotide primers. A number of these transgenic fish showed dramatic increases in their growth rate. At one year old, the average increase of the transgenic fish was 2 to 6 fold and the largest transgenic fish was 13 times that of the average non-transgenic control.

The complete amino acid sequence of growth hormone from sturgeon (Acipencer guldenstadti)

The complete amino acid sequence of growth hormone (GH) from a chondrostean species, the sturgeon (Acipencer gludenstaditi), has been determined. Two variants of GH, termed GH I and GH II, were isolated from the pituitary by alkaline extraction, gel filtration on a Sephadex G-100 column, and reversed-phase high-performance liquid chromatography (rpHPLC) on a TSK gel ODS-120T column. The purified proteins were confirmed to be GHs by immunoblotting using bovine and chum salmon GH antisera. For determining of the primary structures, these GHs were digested with lysyl endopeptidase and cleaved with cyanogen bromide. The resulting fragments were separated by rpHPLC and subjected to sequence analysis on an automated gas-phase sequencer employing an Edman method. Both GHs consist of 190 amino acid residues, and contain two disulfide linkages at positions 52-163 and 180-188. The GHs differ from each other at only three positions. Sequence comparison with GHs from other vertebrates revealed that sturgeon GHs have greater sequence homology with tetrapod GHs (63-76%) than with teleost GHs (42-63%).

Structure and sequence of the growth hormone-encoding gene from Tilapia nilotica

We report here the nucleotide (nt) sequence of the growth hormone (GH)-encoding gene (GH) of the tilapia fish (Tilapia nilotica). The T. nilotica GH gene, similar to that of the salmonidae fish, Atlantic salmon and rainbow trout, contains six exons and five introns. However, despite the presence of an additional intron (intron V), the size of the primary transcript of T. nilotica GH (1666 nt) is significantly shorter than that of all other currently characterized fish GH genes. Comparison of sequences upstream from the transcription start point of the tilapia, carp, rainbow trout and Atlantic salmon GH genes shows a region of high homology preceding the typical TATA box. This homology does not seem to extend to the regions further upstream of the compared fish GH genes and is not observed to be present in the corresponding region of the mammalian GH genes. A sequences search for putative DNA-binding domains for transcription factors shows the presence of short nt stretches similar to those considered to be involved in the tissue-specific expression of mammalian GH genes.

The complete nucleotide sequence of the Atlantic salmon growth hormone I gene

Two closely related genes encoding growth hormone were isolated from Atlantic salmon by genomic cloning. From one of these genes a total of 6500 nucleotides were determined including 3900 nucleotides in exons and introns and about 600 and 2000 nucleotides in 5' and 3' flanking regions. The gene is organized in six exons and encodes a polypeptide of 210 amino acids including a 22 amino acids signal sequence. The promoter region contains a typical TATA box 21 nucleotides upstream from the transcription start site. At the 3' end, three putative poly(A) signal sequences are present. The last two are within a 121 nt inverted repeat.

Structure of the chicken growth hormone-encoding gene and its promoter region

We have cloned the chicken (c) growth hormone (GH)-encoding gene cGH and analyzed its nucleotide sequence including 500 bp of the 5'-flanking region. The cGH gene consists of five exons and four introns as has been observed in the mammalian GH genes. However, the size of the cGH gene is significantly larger than that of analogous mammalian genes, because of its intron size which expands it to 3.5 kb. The transcription start point was determined to be 56 bp upstream from the start codon by the primer-extension analysis. The promoter region of the cGH gene has no overall homology with the corresponding regions of mammalian genes, but contains a short (24 bp) sequence which is highly homologous to the antisense strand sequence of the proximal binding site for a pituitary-specific transcription factor, GHF-1/Pit-1, in the promoter region of the rat GH gene.

Cloning and sequencing of the grass carp (Ctenopharyngodon idellus) growth hormone gene

An enriched lambda gt11 library for screening the grass carp (Ctenopharyngodon idellus) growth hormone gene was constructed using HindIII digested genomic DNA extracted from the spleen of the fish. Probing this library with a homologous cDNA, a clone carrying the growth hormone gene was obtained. The gene is 2501 bp long and consists of five exons and four introns. The sequence of nucleotide in the exons is almost identical to that of the cDNA except for ten positions. Analysis of the 5' sequence up to 1220 bp from the +1 position reveals the presence of a TATA box as well as a number of consensus regulatory sequences. Comparison of the grass carp growth hormone gene with those of other fish indicates that there is a high degree of homology with the gene from the common carp but not with those from the rainbow trout and Atlantic salmon.

Cloning and sequencing of the gilthead seabream (Sparus aurata) growth hormone-encoding cDNA

The cDNA clones encoding gilthead seabream (gsb) (Sparus aurata) growth hormone (GH) have been isolated from a cDNA library prepared from seabream pituitary gland poly(A)+ RNA. The cDNA library was screened using red seabream and rainbow trout GH cDNAs. The complete nucleotide (nt) sequence of gsbGH has been determined. The cDNA sequence codes for a polypeptide of 204 amino acids (aa), including a putative signal peptide of 17 aa. The 5'- and 3'-untranslated regions of the message are 55 and 236 nt long, respectively. The predicted aa sequence of gsbGH revealed 97% homology with red seabream GH, 95% with tuna GH, 85% with yellowtail GH, and 65% with rainbow trout GH.

Purification and characterization of Atlantic salmon growth hormone and evidence for charge heterogeneity

Highly purified growth hormone (GH) has been isolated from Atlantic salmon (Salmo salar) pituitaries by extraction with acid acetone, acidic precipitation, and reversed-phase high-performance liquid chromatography (HPLC). The yield was 2.5 mg/g wet tissue. The Atlantic salmon GH (sGH) emerged as a single symmetrical peak after HPLC on a reverse phase C18 column. SDS-gel electrophoresis revealed only one band with an estimated molecular weight of 23,000. Atlantic sGH showed a uniform molecular weight, but two-dimensional (2D) gel electrophoresis of the purified sGH revealed charge heterogeneity with pI's ranging from 6.5 to 8.2. Treatment of the purified sGH with alkaline phosphatase concentrated these different forms into a single more alkaline position (pI 8.2) indicating removal of acidic groups. These results were documented using both silver- and immunostaining of the 2D SDS gels. The purified sGH was phosphorylated in vitro by a calmodulin-dependent protein kinase. Phosphorylation of sGH may be a post-translational modification resulting in several molecular forms with variable acidity. Analysis of the amino acid composition of Atlantic sGH revealed homology with GHs isolated from other teleost species and the amino-terminal sequence showed only three different amino acids within the first 25 residues compared to GH isolated from chum salmon (Oncorhynchus keta) and coho salmon (Oncorhynchus kisutch) pituitaries. Atlantic sGH had a methionine as the amino-terminal residue. Antibodies against chum sGH cross-reacted with Atlantic sGH. Antibodies against either Atlantic or chinook (Oncorhynchus tschawytscha) salmon prolactin or human GH did not cross-react with Atlantic sGH. Atlantic sGH was shown to have a slight growth-promoting activity in the rat tibia assay.

The complete nucleotide sequence of the growth-hormone gene from the common carp (Cyprinus carpio)

We have isolated and sequenced a phase clone from a common carp (Cyprinus carpio) genomic library that carries a gene encoding growth hormone (GH). This gene consists of five exons and four introns spanning a region of about 3 kilobase pairs. Its exons correspond with one of two reported cDNAs of carp GH except for nine differences in the nucleotide sequence, while the encoded amino-acid sequences are identical. The sequence upstream from the transcription start point contains two tandem repeats of AACTCTCATG (from -85 to -62) and the typical TATA box. All the introns start with a consensus GT dinucleotide and end with AG. The arrangement of exons and introns is very similar to that seen in mammalian GH, but quite different from the GH genes of rainbow trout and Atlantic salmon.