Primary structure of eel (Anguilla japonica) growth hormone

Atlantic halibut growth hormone: structure and plasma levels of sexually mature males and females during photoperiod-regulated annual cycles

The main objectives of this study were to obtain the amino acid sequence of Atlantic halibut (Hippoglossus hippoglossus) growth hormone (hhGH) and compare it with other teleost species, to establish a radioimmunoassay to assess plasma hhGH levels and thus to gain information about possible biological functions and regulation by photoperiod. The hhGH gene was cloned and its amino acid sequence deduced from the cDNA. The mature hhGH protein consists of 186 amino acids. Comparison with other flatfish species as well as a species from a different order, the pufferfish, reveals that the sequence similarities of the mature hhGH with that of the barfin flounder, the Japanese flounder, the sole and the pufferfish are 99.5, 81.7, 74.2, and 65.2%, respectively. The sequence similarities appear to correctly reflect the gross phylogenetic relationships among these teleost species. A specific GH-RIA was developed for measurements of Atlantic halibut GH levels. Assessment of plasma GH levels in adult halibut revealed large gender differences, with GH levels frequently being an order of magnitude higher in males than females. The mean (+/-SEM) plasma GH for males kept on normal annual photoperiod were 25.2+/-6.11 ngml(-1) and for females were 5.14+/-1.94 ngml(-1). It appears likely that plasma growth hormone levels in Atlantic halibut can be inversely correlated to growth and metabolism. Shifting of the annual photoperiod cycles demonstrated that photoperiod in not a regulator of plasma GH levels in the Atlantic halibut, but further research is needed to assess whether GH plays a role in the reproduction of this marine teleost species.

Differential secretion of chicken growth hormone variants after growth hormone-releasing hormone stimulation in vitro

Variants of growth hormone (GH) are present in most vertebrates. Chicken GH (cGH) undergoes posttranslational modifications that contribute to its structural diversity. Although the 22-kDa form of GH is the most abundant, some other variants have discrete bioactivities that may not be shared by others. The proportion of cGH variants changes during ontogeny, suggesting that they are regulated differentially. The effect of growth hormone-releasing hormone (GHRH) on the release of cGH variants was studied in both pituitary gland and primary cell cultures, employing sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and densitometry. GHRH (2 nM, 2 h) stimulated the secretion of most of the size variants of cGH although the amplitude of increase was not equal for each one. A differential effect on the secretion of GH size variants, particularly on the 22- (monomer) and 26-kDa (putatively glycosylated) cGH isoforms was found in both systems. In the whole pituitary culture, the proportion of the 26-kDa immunoreactive cGH increased 35% while the 22 kDa decreased 31% after GHRH treatment in comparison with the controls. In the primary cell culture system, the proportion of the glycosylated variant increased 43% whereas the monomer and the dimer decreased 22.26 and 29%, respectively, after GHRH stimulation. Activators of intracellular signals such as 1 mM 8-bromo-cAMP and 1 microM phorbol myristate acetate had a similar effect to that obtained with GHRH. The data support the hypothesis that GH variants may be under differential control and that GHRH promotes the release of a glycosylated cGH variant that has an extended half-life in circulation.

Purification, characterization, and bioassay of prolactin and growth hormone from temperate basses, genus Morone

Prolactin (PRL) and two variants of growth hormone (GH), purified from pituitaries of striped bass (Morone saxatilis) and its hybrid with white bass (M. saxatilis x M. chrysops) by gel filtration chromatography under alkaline conditions followed by reversed-phase high pressure liquid chromatography, appear similar between species. Both the minor (GH I) and the major (GH II) forms of purified GH appeared as single bands (M(r) approximately 23,000) after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, as did the purified PRL (M(r) approximately 24,000). The molecular weights of GH II and PRL determined by MALDI TOF mass spectroscopy were 21.2 and 21.3 kDa, respectively. In Western blotting experiments, an antiserum against tilapia (Oreochromis mossambicus) 24K PRL specifically recognized Morone PRL, while an antiserum against tilapia GH specifically recognized Morone GH I and II. Chemical identities of the putative PRL and GH I were further confirmed by N-terminal peptide sequencing, while internal sequence analysis was performed on GH II because it was blocked at its N-terminus. Over a stretch of 29 amino acids, Morone PRL was found to be 76% identical to tilapia 24K PRL, 72% identical to tilapia 20K PRL, 72% identical to chum salmon (Oncorhynchus keta) PRL I, and 69% identical to eel (Anguilla japonica) PRL I. Alignment of the hybrid striped bass GH sequences with those of several other advanced marine teleosts indicated 75-85% sequence identity for GH I (40 amino acids) and 95-98% identity for GH II (45 amino acids). Biological activity of striped bass GH II was confirmed using a heterologous in vitro assay of insulin-like growth factor I mRNA production by coho salmon (On. kisutch) hepatocytes. An in vivo bioassay, involving hypophysectomy of hybrid striped bass and treatment of the fish maintained in fresh water with homologous PRL, confirmed that the purified striped bass PRL was also bioactive.

Studies on the GH/SL gene family: cloning of African lungfish (Protopterus annectens) growth hormone and somatolactin and toad (Bufo marinus) growth hormone

The lungfishes (lobe-finned fish) occupy a unique position in vertebrate phylogeny, being regarded as the closest extant relatives to the tetrapods. The putative pituitary hormone somatolactin (SL) has hitherto been found only in teleost fishes, and the presence of this protein in tetrapods or lobe-finned fishes has not been ascertained. It was therefore of interest to determine the structure of SL in the African lungfish (Protopterus annectens), as this information would be useful for designing probes to facilitate the detection of SL genes in amphibians and other tetrapods. The structural relationships between SL, growth hormone (GH), and prolactin (PRL) strongly suggest that these proteins evolved from a common ancestor. To obtain a more complete picture of the evolution of these hormones in lungfish, African lungfish GH has been cloned and sequenced. The cDNA sequence of a toad (Bufo marinus) GH was determined to facilitate maximum parsimony analysis of GH sequences. Cladistic analysis confirmed that lungfish and amphibian GH sequences form a clade distinct from the GH sequences of ray-finned fishes. A distance matrix analysis of SL sequences indicated that lungfish SL had the lowest primary sequence identity with goldfish SL (47%) and the highest with flounder SL (66%). The detection of SL in a lungfish indicates that the gene duplication within the SL/GH/PRL family, which gave rise to SL, must have occurred in a common ancestor of the ray-finned fishes (Actinopterygii) and the lungfishes (Sarcopterygii) and tetrapods.

Growth hormone, sexual maturity and steroids in male carp (Cyprinus carpio)

Samples of pituitary, blood plasma and gonad were taken from male carp. The growth hormones (GH) in the pituitary and plasma were measured in fish of various body weights (BW) and degrees of gonad development, and compared with the levels of 17 beta-estradiol (E2), testosterone (T), 17 alpha-hydroprogesterone (17-P), 11-ketotesterone (11-KT) and progesterone (P) in the testes and plasma. The gonadosomatic index increased rapidly with BW from 100 to 600 g, and then decreased at 900 g. The pituitary GH did not change with BW, but plasma GH was higher in fish weighing 300 +/- 50 and 600 +/- 50 g, than in fish weighing 900 +/- 50 g. In fish weighing 150 +/- 50 to 300 +/- 50 g, the level of T rose significantly in the testes (2.27 ng g-1) and plasma (1.3 ng g-1); E2 was very low in both testes (0-30 pg g-1) and plasma (11-28 pg ml-1), increasing as BW rose from 150 to 600 g. The level of P rose mainly at BW of 300 +/- 50 and 600 +/- 50 g: from 0 to 25 ng g-1 in the testes and from 0 to 17 ng ml-1 in the plasma. The level 17-P rose from 2.5 to 20 ng g-1 in the testes at 600 +/- 50 g BW, but no significant change was recorded in the plasma. The level of 11-KT rose significantly in the tests of fish at 300, 600 and 900 g (0.5-6 ng g-1). The application of different steroids (E2, T and 17-P) on a primary culture of pituitary cells led to the release of GH. Release was significantly higher (P < 0.05) after 4 h at steroid concentrations of 10(-6) M.

Structure and function of bovine growth hormone. Bovine growth hormone as an experimental model for studies of protein-protein interactions

Growth hormone (GH) is a polipeptide that controls the differentiation, growth and metabolism of many cell types, and is secreted from the hypophysis of all vertebrate species tested so far. Despite the overlapping evolutionary, structural, immunological and biological properties, it is well-known that GHs from distinct mammalian species have significant species-specific characteristics. The main purpose of this review is to highlight bovine GH (bGH) structural features related to its species-specific properties. Novel interest in bGH is also aroused by the advent of biotechnological methods for production of recombinant proteins. In fact recombinant bGH will have a great importance in veterinary medicine research and as a 'high tech' drug that needs to be monitored in zootechnical productions.

Growth hormone, gonad development, and steroid levels in female carp

The pituitary and plasma growth hormone (GH) levels of female carp (Cyprinus carpio L.) were measured in fish of various sizes and degrees of maturity, and were matched against the levels of 17 beta-estradiol (E2), testosterone (T), 17 alpha-hydroxyprogesterone (17-P), and progesterone (P) in the ovary and plasma. The short-term action of the above hormones and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17,20-P) on the release of GH was examined in vitro in primary culture pituitary cells. The gonadosomatic index (%GSI) increased rapidly in specimens when they had attained 900 +/- 50 g body weight (BW). The pituitary and plasma GH levels increased between 150 and 600 g BW (when oocytes reached the stage at which lipoprotein appeared in the cytoplasm), but at 900 g BW (with oocytes in vitellogenesis) the plasma GH dropped, while pituitary GH remained high. E2 increased with BW, reaching its maximum at 600 and 900 g BW in the ovary and plasma, respectively. Similar patterns were found in the levels of T and P, both hormones reaching their maximum levels at 900 g BW. The level of 17-P was very low and did not increase in proportion to BW. The application of various concentrations of different steroids on a primary culture of pituitary cells led to release of GH. The highest degrees of release were obtained from 10(-6) and 10(-7) M E2, 10(-6) M T, 10(-7) M 17-P and 10(-8) M 17,20-P. In all these cases, hormone treatment effected higher release of GH than was found in the control. A model of the relationship between GH and the steroids associated with maturation is proposed.

The primary structures of growth hormones of three cyprinid species: bighead carp, silver carp, and grass carp

The primary structures of growth hormone (GH) of three cyprinid species, bighead carp, silver carp, and grass carp, were determined by a chemical method and/or by molecular cloning. The bighead carp GH was extracted from pituitary tissue by use of an alkaline medium, then successively purified by gel filtration, hydrophobic interaction column chromatography, and reverse-phase high-pressure liquid chromatography. The primary structure of bighead carp GH determined chemically is identical to that deduced from the cDNA nucleotide sequence. By molecular cloning, the primary structures of silver carp and grass carp GHs were also determined. The GHs of these three cyprinid species all contain 188 amino acid residues and their sequences are identical. When four of the five cysteines of cyprinid GHs were arranged to match the same positions of cysteines of other vertebrate GHs, a maximally matched alignment was achieved. Among fishes, GHs are relatively conserved within the same order (82 to 100% identity) but they are more diversified between orders (49 to 68% identity). In further comparison, fish GHs are even more different from tetrapod GHs (37 to 58% identity). Although the primary structures of vertebrate GHs are relatively variable, four homologous sequences, notably one located at the C-terminal, are found.

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%).

The complete amino acid sequence of prolactin from the bullfrog, Rana catesbeiana

The complete amino acid sequence of prolactin (PRL) from an amphibian species, the bullfrog (Rana catesbeiana), has been determined and conserved residues and domains were analyzed by sequence comparison of PRLs from 15 species of five major vertebrate classes. The bullfrog PRL consists of 197 amino acid residues with three disulfide linkages formed between residues 4-11, 58-172, and 189-197. The bullfrog PRL shows the highest identity with sea turtle PRL (75%); lower identities with chicken PRL (72%), pig, horse, and fin whale PRLs (68%), human, cattle, sheep, and elephant PRLs (60-58%), and rat and mouse PRLs (50%); and significantly lower identity with teleost PRLs (about 30%). It is apparent that all tetrapod PRLs characterized so far contain three disulfide bonds in homologous positions and differ from teleost PRLs which lack the N-terminal disulfide loop. The tetrapod and teleost PRLs share 34 common residues and these conserved residues are clustered in six domains (PD1 to PD6), suggesting that these common residues, or at least part of them, are responsible for the activities common to all PRLs. On the other hand, PD5 is conserved significantly within tetrapod PRLs, but to a lesser extent in teleost PRLs, suggesting that the PD5 contributes to the activities specific to tetrapod PRLs.

Immunoaffinity purification and partial characterization of sea bass (Dicentrarchus labrax) growth hormone

Growth hormone (GH) was isolated from sea bass (Dicentrarchus labrax) pituitary extract by a simple one-step procedure involving immunoaffinity chromatography. A monoclonal antibody raised against chicken GH and found to immunostain very specifically the GH cells in the pituitary of the sea bass was coupled to CNBr-activated Sepharose 4B. Sea bass pituitary extracts were run on the affinity column, and the eluted material was analyzed on reversed-phase HPLC and found to consist of one single peak. The yield of purified hormone was 2.4 mg/g pituitary. Two monomeric forms (MW = 20,000 and 22,000 Da) of sea bass GH were identified by gel electrophoresis. Gel electrofocusing revealed apparent isoelectric points of 6.15, 6.50, and 6.95. Amino acid composition is consistent with other vertebrate GHs. The immunological relatedness was tested by immunoblotting using antisera raised against GH of different species. Polyclonal antisera raised against the isolated hormone exhibited a specific labeling of the GH cells in sea bass pituitary sections as well as of the immunoblotted purified GH.

The complete amino acid sequence of growth hormone of the bullfrog (Rana catesbeiana)

The primary structure of growth hormone (GH) isolated from the adenohypophysis of the bullfrogs (Rana catesbeiana) was determined. The hormone was reduced, carboxymethylated and subsequently cleaved with cyanogen bromide. Intact bullfrog GH was also digested with lysyl endopeptidase and trypsin. The resulting fragments were separated by reverse-phase high-performance liquid chromatography and subjected to sequence analysis using an automated gas-liquid sequencer employing the Edman method. Bullfrog GH was found to consist of 190 amino acid residues. The amino acid sequence determined is in accord with that deduced from bullfrog GH cDNA by Pan and Chang (1988) except for nine residues at positions 43-48, 73, 80 and 87. Sequence comparisons revealed that bullfrog GH is more similar to tetrapod GHs (e.g., 69% homology with sea turtle GH, 66% with chicken GH and 61% with ovine GH) than to GHs of teleosts (e.g., 35% homology with chum salmon GH and 33% with bonito GH) except for eel (52% identity). Bullfrog GH and prolactin exhibit a sequence homology of 25%.

Distribution and characterization of immunoreactive growth hormone (GH) in the pituitary of the frog Rana ridibunda using an antiserum against purified bullfrog GH

The presence of growth hormone (GH) in the pituitary of the frog Rana ridibunda was investigated using an antiserum raised against purified bullfrog GH. The immunofluorescence technique revealed that GH-containing cells are exclusively located in the dorsal area of the distal lobe of the pituitary. The relative abundance of these GH-positive cells, which correspond to acidophilic type 2 cells, was 18 +/- 1% of the total population of endocrine cells of the pars distalis. Frontal sections of the distal lobe indicated that GH-producing cells are distributed in an arc of a circle occupying all of the dorsal part of the lobe. At the electron microscopic level, GH-immunoreactive material was sequestered in large polymorphic granules (200-700 nm). GH was quantified in R. ridibunda pituitary extracts using a radioimmunoassay for bullfrog GH. The displacement curves obtained with serial dilutions of pars distalis extracts were not strictly parallel to the standard curve made with purified bullfrog GH. In contrast, Western blot analysis revealed that GH from R. ridibunda had a molecular weight (22 kDa) similar to that of bullfrog GH. In the pars distalis, the apparent amount of GH was 0.61 +/- 0.14 microgram per lobe, corresponding to 0.92 +/- 0.17% of total proteins in the extracts. In contrast, frog neurointermediate lobe or hypothalamus did not contain significant concentrations of immunoreactive GH (less than 0.006% of total proteins in the extracts). Taken together, these results validate the use of an antiserum to bullfrog GH to investigate the regulation of GH secretion in R. ridibunda.

Hepatic receptors for homologous growth hormone in the eel

The specific binding of 125I-labeled eel growth hormone (eGH) to liver membranes of the eel was examined. The specific binding to the 10,000g pellet was greater than that to the 600g pellet. The specific binding was linear up to about 100 mg fresh tissue, and was saturable with increasing amounts of membrane. The specific binding was pH-, temperature-, and time-dependent, with the optimum pH at 7.4, and greater specific binding was obtained at 15 and 25 degrees than at 35 degrees. Scatchard analysis of liver binding gave an association constant of 1.1 x 10(9) M-1 and a capacity of 105 fmol/mg protein. The receptor preparation was highly specific for GHs. Natural and recombinant eel GHs as well as recombinant salmon GH competed equally with 125I-eGH for the receptor sites of the 10,000g liver membrane. Ovine GH was more potent in displacing the labeled eGH than the homologous eel hormone. Tilapia GH and ovine prolactin (PRL) were needed in greater amounts (40 times) than eGH to displace the labeled eGH. Salmon and tilapia PRLs were still less potent (500 times) than eGH. There was no displacement with eel PRL. No significant change in the specific binding was seen 1 week after hypophysectomy, whereas injection of eGH into the hypophysectomized eel caused a significant reduction after 24 hr. The binding to the membrane fractions from gills, kidney, muscle, intestine, and brain was low and exclusively nonspecific, indicating the presence of specific GH receptors predominantly in the liver.

Isolation and characterization of Japanese eel prolactins

A highly purified prolactin (PRL) was isolated from the pituitary of the Japanese eel (Anguilla japonica) by extraction with acid-acetone, gel filtration on Sephadex G-75, and reversed-phase HPLC on TSK-gel ODS 120T and on TSK-gel TMS 250. Eel PRL is comprised of two variants (ePRL I and II), which were separated by HPLC on an ODS column. The two PRLs were also secreted by organ-cultured pituitaries in a defined medium. After being dialyzed against distilled water and lyophilized, the medium was dissolved in 0.01 M ammonium acetate (pH 9.0), and then the insoluble fraction was subjected to HPLC on an ODS column to isolate the secreted PRLs. The ePRL I and II were equipotent in retaining plasma Na in the hypophysectomized killifish, Fundulus heteroclitus, transferred from sea-water to fresh water. The putative PRL-producing cells in the rostral pars distalis of the eel pituitary were specifically stained with the antiserum against the mixture of ePRL I and II. Both PRLs had a molecular weight of 22 kDa in SDS-PAGE, an isoelectric point of 10.1 by gel electrofocusing, and an N-terminal residue of valine. Amino acid compositions and the partial amino acid sequences of ePRL I and II show that they are highly homologous with a limited number of substitutions, and that they are more closely related to those of teleostean PRLs than to those of mammalian PRLs.

Amino acid sequence of growth hormone isolated from medium of incubated pituitary glands of tilapia (Oreochromis mossambicus)

The amino acid sequence of tilapia (Oreochromis mossambicus) growth hormone (GH) was determined directly by Edman degradation of peptide fragments generated by lysyl endopeptidase and trypsin digestion. The N-terminal residue was deduced to be pyroglutamic acid through the use of pyroglutamyl aminopeptidase; its removal allowed amino acid sequence determination of the remainder of the N-terminal trypsin peptide by Edman degradation. Tilapia GH is composed of 187 amino acid residues and shows high similarity to other perciform GHs. Sequence identities are: 89% with tuna GH, 83% with bonito GH, 85% with yellowtail GH, 89% with red sea bream GH, and 34% with bovine GH. The two asparagine residues (Asn-148 and Asn-184) were recovered by Edman degradation, suggesting the absence of N-glycosylation.

The complete amino acid sequences of two variants of growth hormone from Atlantic cod (Gadus morhua)

The complete amino acid sequences of two variants of cod growth hormone (GH) have been determined. The GHs, which have apparent molecular weights of 20K and 22K in SDS-PAGE, consist of 185 amino acids and have calculated molecular weights of 20,733 and 20,805, respectively. Comparison of the two sequences showed only one amino acid difference between the variants, with Lys at position 151 in the 22K GH changed to Gly in the 20K GH. The substitution of a charged amino acid by one which contains no sidechain might be expected to be reflected in the isoelectric point of the molecule. However, the observed pI for both the 20K and 22K GHs was 5.8. The difference in apparent molecular weights by SDS-PAGE suggests the existence of a conformational difference between the variants which is attributable to the observed substitution. This conclusion is in agreement with our previous data obtained from radioimmunoassay studies where the 20K GH shows only 25% cross-reactivity in an assay developed for the 22K GH. Alignment of the cod GH sequence with those of other teleost GHs reveals cod GH to be most similar to advanced marine fish such as tuna, sea bream, bonito, and yellowtail (76-83% identity), whereas it is 62-66% identical to flounder and chum salmon 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.

Isolation and characterization of recombinant eel growth hormone expressed in Escherichia coli

To obtain information about the microheterogeneity of recombinant protein, recombinant eel growth hormone II (EGH) analogues expressed in Escherichia coli were isolated and characterized. The modification was classified into three types: monodeamidation of Asn, oxidation of Met and N-terminal formylation. Monodeamidated EGH was isolated by ion-exchange chromatography. The major deamidation site (Asn 147) was determined by peptide mapping using the substrate specificity of trypsin. Oxidized EGH and N-terminal-formylated EGH were isolated by reversed-phase high-performance liquid chromatography. Oxidized EGH was identified by amino acid composition analysis and N-terminal-formylated peptide by mass spectrometry.

Growth hormone secretion during longterm incubation of the pituitary of the Japanese eel, Anguilla japonica

Growth hormone (GH) secretion from organ-cultured pituitaries of the eel (Anguilla japonica) was studied during incubation in a defined medium for 2 weeks, using a homologous radioimmunoassay which does not distinguish between the two molecular forms of eel GH. The total amount of GH secreted increased gradually during the incubation period; so that the amount of GH released on day 14 was about 30 times greater than that on day 1. On day 14, the proportion of GH released relative to the total amount of GH present (the sum of GH released into the medium and residual content in the pituitary) was 96% and the amount produced on day 14 was 4 times greater than the content in the unincubated pituitary. Somatostatin (SRIF, 1.8 × 10(-7) M) inhibited the increase in GH release. On day 7, the proportion of GH released by pituitaries treated with SRIF (28%) was less than that released by the control pituitary (91%). There was no significant difference in GH release between the pituitaries incubated in isotonic medium (300 mOsm) and those in hypotonic medium (240 mOsm) for 2 weeks except for the first 3 days, when the pituitaries in hypotonic medium secreted significantly greater amounts of GH than those incubated under isotonic condition. Hypertonic medium (350 mOsm) had no effect on GH release except for significant inhibition on days 6 and 14. When secretion of the two forms of GH (GH I and II) was examined after separation by polyacrylamide gel electrophoresis followed by densitometry, slightly more GH I tended to be secreted than GH II during the culture period, although the effects of SRIF and osmolality of the media on GH I release were similar to those on GH II. It is concluded that GH secretion and production in the eel is mainly under the inhibitory control of hypothalamus, and that osmolality has a minimum influence on the GH release.

Unequal activities of the two tilapia prolactins in the whole-animal transepithelial potential bioassay using the red eft

The cichlid fish tilapia (Oreochromis mossambicus) produces two forms of prolactin (tPRL177 and tPRL188) at equal rates. The primary sequences of this prolactin pair share only 69% identity. In these experiments, the whole-animal transepithelial potential (TEP) in the eft stage of the red-spotted newt (Notophthalmus viridescens) was measured in response to two injections totaling about 2 μg of tPRL177, tPRL188, ovine PRL, or tilapia growth hormone (tGH), or distilled water (5 μL/injection). This investigation was undertaken in order to locate prolactin receptors which discriminate between the two molecular forms of tilapia prolactin. The salamandrid integumental bioassay for prolactin was found to respond to tPRL177 as it does to ovine PRL. The more mainline tPRL188 was without effect at this dose and thus behaved more similarly to growth hormone (tilapia and ungulate) in this bioassay. The suspected magnitude of differences in the molecular surface characteristics between the two prolactins seem to be adequate to allow the binding of tPRL177 and to hinder the binding of tPRL188 to prolactin specific receptors in eft epithelial tissues.

Purification and characterization of bullfrog growth hormone

A highly purified growth hormone (GH) was isolated from an unadsorbed fraction obtained by subjecting acid acetone extract of bullfrog pituitary glands to DEAE-cellulose column chromatography, a side fraction obtained during the purification of prolactin, by cation-exchange chromatography on CM-Toyopearl and high-performance liquid chromatography on ODS with a yield of 5.6 mg/g protein of the starting material. Intraperitoneal injections of GH to hypophysectomized Xenopus resulted in a considerable elevation of chondroitin sulfate synthesis in the xiphisternal cartilage as measured in vitro. The bullfrog GH had a molecular weight of 22,000 Da as determined by sodium dodecyl sulfate-gel electrophoresis. The isoelectric point of bullfrog GH was estimated to be 7.8 by gel electrofocusing. The partial amino acid sequences of bullfrog GH at both terminal regions were determined.

The complete amino acid sequence of growth hormone from the sea turtle (Chelonia mydas)

The complete amino acid sequence of growth hormone (GH) from a reptilian species (the sea turtle, Chelonia mydas) has been determined for the first time. The hormone was reduced, carboxymethylated, and subsequently cleaved in turn with cyanogen bromide and Staphylococcus aureus protease. The intact protein was also cleaved with lysyl endopeptidase and o-iodosobenzoic acid. The resulting fragments were exclusively separated by reversed-phase high-performance liquid chromatography and subjected to sequence analysis by automated gas-phase sequencer employing the Edman method. The sea turtle GH consist of 190 amino acid residues with two disulfide linkages formed between residues 52-160 and 180-188, and possesses a microheterogeneity, indicated by the presence or absence of an additional alanine residue at the N-terminus. Sequence identities of sea turtle GH to other species of GH are 89% with chicken GH, 79% with rat GH, 68% with blue shark GH, 58% with eel GH, 59% with human GH, and 40% with a teleostean GH such as chum salmon. On the basis of amino acid sequence comparisons, a molecular phylogenetic tree is proposed.

The complete amino acid sequence of growth hormone of an elasmobranch, the blue shark (Prionace glauca)

The complete amino acid sequence of growth hormone (GH) from a phylogenetically ancient fish, the blue shark (Prionace glauca), was determined. The shark GH isolated from pituitary glands by U. J. Lewis, R. N. P. Singh, B. K. Seavey, R. Lasker, and G. E. Pickford (1972, Fish. Bull. 70, 933-939) was purified by reversed-phase high-performance liquid chromatography. The hormone was reduced, carboxymethylated, and subsequently cleaved in turn with cyanogen bromide and Staphylococcus aureus protease. The intact protein was also cleaved with lysyl endopeptidase and o-iodosobenzoic acid. The resulting peptide fragments were separated by rpHPLC and submitted to sequence analysis by automated and manual Edman methods. The shark GH consists of 183 amino acid residues with a calculated molecular weight of 21,081. Sequence comparisons revealed that the elasmobranch GH is considerably more similar to tetrapod GHs (e.g., 68% identity with sea turtle GH, 63% with chicken GH, and 58% with ovine GH) than teleostean GHs (e.g., 38% identities with salmon GH and 42% with bonito GH) except for eel GH (61% identity), and substantiates the earlier finding derived from the immunochemical and biological studies (Hayashida and Lewis, 1978) that the primitive fish are less diverged from the main line of vertebrate evolution leading to the tetrapod than are the modern bony fish.

Isolation and characterization of growth hormone from Atlantic cod (Gadus morhua)

Growth hormone was purified from cod pituitary extract by a simple two-step procedure involving gel filtration and reversed-phase high-performance liquid chromatography (rpHPLC). At each stage of purification, fractions were monitored by rpHPLC, SDS-polyacrylamide gel electrophoresis, and immunoblotting using anti-chum salmon growth hormone (GH) antiserum. The yield of purified hormone was 1.3 mg/g pituitary. Cod GH was found to exist in two monomeric forms (Mr = 20K and 22K) and dimeric forms (Mr = 40K and 42K). The two monomeric forms have a pI of 5.8, an identical amino acid composition, histidine as the N-terminal residue, and an identical lysyl endopeptidase peptide map. Staining with concanavalin A was observed on the 20K component only, but analysis for total reducing sugar did not confirm these results. Cod GH was found to be a potent stimulator of growth in juvenile rainbow trout which received intraperitoneal injections of the hormone. The partial amino acid sequence has been determined.

Molecular cloning of eel growth hormone cDNA and its expression in Escherichia coli

cDNA clones coding for growth hormone (eGH) of Japanese eel (Anguilla japonica) have been isolated from a cDNA library prepared from pituitary gland poly(A)+ RNA. The nucleotide sequence of the eGH cDNA was determined. It codes for the prehormone of 209 amino acids (aa) including a putative signal peptide of 19 aa. The deduced amino acid sequence was identical with that determined for eGH protein. The primary structure of eGH was compared with those of other species growth hormones (chum salmon, chicken, rat, and human). Mature eGH was expressed in Escherichia coli harboring a plasmid in which the eGH cDNA was under control of the phage lambda pL promoter. Recombinant eGH polypeptide was immunoreactive to rabbit antiserum against natural eGH. Furthermore, eGH derivative with amino-terminal deletion (delta 1-3 eGH) was produced in E. coli reaching up to 5% of total cellular proteins.

Isolation and characterization of growth hormone from a marine fish, bonito (Katsuwonus pelamis)

Growth hormone (GH) was extracted under alkaline conditions (pH 10) from pituitary glands (6.3 g) of bonito (Katsuwonus pelamis), and subsequently purified by gel filtration, ion exchange chromatography, and reversed-phase HPLC. The GH was monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and by immunoblotting with yellowtail GH antiserum at each step of purification. GH activity was determined by an in vivo bioassay. The yield of this hormone was 4.8 mg/g wet tissue. Intraperitoneal injection of bonito GH at doses of 0.1 and 1 micrograms/g body wt at 7-day intervals resulted in a significant increase in body weight and length of juvenile rainbow trout. Bonito GH antiserum exhibited both species and hormone specificity in radioimmunoassay. However, the bonito GH antiserum as well as yellowtail GH antiserum exhibited hormone specificity but not species specificity in immunoblotting. A molecular weight of 21,000 and an isoelectric point of 7.0 for bonito GH were estimated by SDS-PAGE and gel electrofocusing, respectively. The complete amino acid sequence of 185 residues was determined by sequencing fragment peptides prepared by chemical and enzymatic cleavages. Sequence comparison of bonito GH with other GHs revealed that there is a significant deletion in the middle of the molecule.

cDNA cloning and primary structure of yellow tail (Seriola quinqueradiata) pregrowth hormone

Full-length cDNA of yellow tail (Seriola quinqueradiata) growth hormone (GH) was cloned from the pituitary gland and nucleotide sequence was analyzed. The cDNA clone contained one open reading frame to encode a preprotein consisting of 204 amino acids. The deduced amino acid sequence shows two possible sites for signal peptide cleavage, suggesting that the mature forms of yellow tail growth hormone consist of 185 or 187 amino acids. Yellow tail growth hormone exhibits a typical structural feature as growth hormone, including four cysteine residues to form two disulfide bonds and other identical amino acids with other vertebrate GHs. Amino acid sequence of yellow tail growth hormone shows homology of approximately 66, 42, 37, and 34% with those of salmon, eel, bovine, and human GHs, respectively. Nucleotide sequence of the coding region of yellow tail growth hormone cDNA shows approximately 58 and 40% homology with those of salmon and human growth hormone cDNAs, respectively.