Occurrence of a new melanocyte stimulating hormone in the salmon pituitary gland

A new melanocyte stimulating hormone has been identified in the pituitary of the teleost, $\text{Oncorhynchus keta}$ (chum salmon). The newly isolated MSH like peptide is a heptadeca peptide, which differs in size from salmon α-MSH (13 residues) and β-MSH I and II (17 residues each). The structural determination, however, revealed that it is similar to but distinct form α-MSH, with following amino acid sequence, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Ile-Gly-His-OH. This peptide, named α-MSH II is the third line of evidence in the salmon that the teleost pituitary gland secretes two different forms of processed hormones, for which the precursor molecules are coded on two separate genes.     

Occurrence of a new corticotropin-like intermediate lobe peptide in salmon pituitary glands

A new corticotropin-like intermediate lobe peptide (CLIP) has been identified in the pituitary of chum salmon, Oncorhynchus keta. The newly isolated peptide is a tetracosa peptide, which is two residues longer than the predominant form, CLIP I, with the following amino acid sequence, H-ArgProIleLysValTyrAlaSerSerLeuGlu GlyGlyAspSerSerGluGlyThrPheProLeuGlnAlaOH. This peptide, named CLIP II is the fourth line of evidence in the teleost that the pituitary gland secretes two different forms of processed hormones, for which precursor molecules are coded on two separate genes. Together with the structures of α-melanotropin I and II, two putative ACTH molecules are proposed.     

N-Acetylated endorphins in ovine anterior pituitary and neuro-intermediate lobe

We have used an antiserum for immunohistochemistry and RIA/RP-HPLC which recognizes all fragments of N-acetylated endorphin (NacEP). In the rat neurointermediate lobe (N-IL), in addition to the N-acetylated forms of immunoreactive-β-endorphin (ir-βEP) already reported, we have demonstrated NacβEP_1–17 as a minor component. In the sheep pituitary processing of βEP is markedly different. In the anterior pituitary (AP), staining was indistinguishable with βEP and NacEP antisera, in contrast with the rat where many fewer AP cells stained with the NacEP antiserum. Secondly, as in the rat, all N-IL cells stained with both antisera; on RP-HPLC, however, the major forms of NacEP in the sheep N-IL were NacβEP_1–17 (40%), NacβEP_1–27 (25%) and NacβEP_1–16 (20%), with NacβEP_1–31 (2%) as a minor component. A similar profile was seen on RP-HPLC of sheep AP. These data suggest that (1) patterns of processing in sheep AP are similar to those in N-IL, though the extent of acetylation is less and (2) in the sheep pituitary low molecular weight acetylated fragments predominate, in contrast with the rat.     

Characterization of endorphins from the pituitary of the spiny dogfish Squalus acanthias

Opioid-like immunoreactive material was extracted from the pituitary and brain of the Spiny Dogfish Shark Squalus acanthias. The immunoreactive material in the pituitary extracts was purified to apparent homogeneity by reverse phase high performance liquid chromatography and subsequently characterized by amino acid analysis, Edman degradation and fast atom bombardment mass spectrometry. The largest opioid-like peptide isolated contained 30 amino acids and showed 80 percent homology with salmon endorphin-II but less than 50 percent homology with human beta-endorphin. Three structural variants of this molecule were also characterized. These variants were shown to be shorter N-terminal fragments, two of which corresponded to cleavage products at the single basic residues arginine and lysine. Cleavage at a single lysine residue has not been reported for posttranslational processing of beta-endorphin in mammals and could represent a modification seen only in lower vertebrates. The remaining fragment corresponded to a loss of 3 residues from the C-terminus of the parent molecule. No alpha-N-acetylated peptides were detected. These results provide the first unequivocal confirmation of beta-endorphin in an elasmobranch and provide evidence of novel N-terminal variants of beta-endorphin.     

Primary structure of two mRNAs encoding putative salmon alpha-subunits of pituitary glycoprotein hormone

1. By random sequence analyses, we isolated from the cDNA library of salmon pituitary glands two clones, the deduced amino acid sequences corresponding to the C-terminal region of which are almost the same as those of the alpha subunits of mammalian glycoprotein hormones. 2. Comparison of the nucleotide sequences and deduced amino acid sequences from these two clones with those of mammalian species revealed that the two newly-isolated cDNAs corresponded to mRNAs encoding the putative salmon pre-alpha subunit of glycoprotein hormones. 3. Homology in the nucleotide sequences of these two clones suggested that corresponding mRNAs may be encoded by separate genes which probably evolved from a common ancestral gene.     

Occurrence of two different pathways in the activation of porcine pepsinogen to pepsin

Activation of porcine pepsinogen at pH 2.0 was found to proceed simultaneously by two different pathways. One pathway is the direct conversion process of pepsinogen to pepsin, releasing the intact activation segment. The isolation of the released 44-residue segment was direct evidence of this one-step process. At pH 5.5 the segment bound tightly to pepsin to form a 1:1 pepsin-activation segment complex, which was chromatographically indistinguishable from pepsinogen. The other is a stepwise-activating or sequential pathway, in which pepsinogen is activated to pepsin through intermediate forms, releasing activation peptides stepwisely. These intermediate forms were isolated and characterized. The major intermediate form was shown to be generated by removal of the amino-terminal 16 residues from pepsinogen. The released peptide mixture was composed of two major peptides comprising residues 1-16 and 17-44, and hence the stepwise-activating process was deduced to be mainly a two-step process.     

Occurrence of Atlantic salmon in the Douro River: Recent evidence

Two adult Atlantic salmon, Salmo salar, were netted in 2015 and 2017 during a study conducted in the terminal stretch of the Douro River, after more than 20 years without confirmed records of the species occurrence in the southern limit of its European range. According to professional fisherman operating in the area, a few adult Atlantic salmon are caught every year in this river stretch. Further work should be conducted to assess if the species is reproducing in the Douro River and the overall status of its populations in the North of Iberia.     

Quantitative analysis of fushi tarazu factor 1 homolog messenger ribonucleic acids in the pituitary of salmon at different prespawning stages

Steroidogenic factor 1 (SF-1) or Ad4BP is a member of the fushi tarazu factor 1 (FTZ-F1) family and an orphan nuclear receptor that plays an important role in the hypothalamus-pituitary-gonadal axis and the adrenal cortex. Although its critical role in the differentiation of adrenals, gonads, and pituitary gonadotropes has been well demonstrated, regulatory function of SF-1 during sexual maturation is yet to be examined. To investigate the potential role of SF-1 in sexual maturation, expression of two salmon FTZ-F1 homolog genes, sFF1-I and sFF1-II, was examined in the pituitaries of chum and sockeye salmons, using specific and sensitive RNase protection assays. Only sFF1-I mRNA was found in the pituitary and other organs, such as the ovary, spleen, liver, brain, and skeletal muscle. In chum salmon during upstream migration from the bay to the hatchery, the level of sFF1-I mRNA in the male fish was increased on the midway in the river, where the levels of gonadotropin alpha- and II beta-subunit mRNAs were increased. In maturing sockeye salmon, the expression of the sFF1-I gene was elevated in the mature male fish, but the administration of GnRH analog did not further enhance the expression. These results indicate that sFF1-I gene expression in the pituitary is upregulated in maturing salmon, and this upregulation may not depend on GnRH.     

Occurrence of two different forms of protocatechuate 3,4-dioxygenase in a Moraxella sp

Two alternative forms of protocatechuate 3,4-dioxygenase (PCase) have been purified from Moraxella sp. strain GU2, a bacterium that is able to grow on guaiacol or various other phenolic compounds as the sole source of carbon and energy. One of these forms (PCase-P) was induced by protocatechuate and had an apparent molecular weight of 220,000. The second form (PCase-G) was induced by guaiacol or other phenolic compounds, such as 2-ethoxyphenol or 4-hydroxybenzoate. It appeared to be smaller (Mr 158,000), and its turnover number was about double that of the former enzyme. Both dioxygenases had similar properties and were built from the association of equal amounts of nonidentical subunits, alpha and beta, which were estimated to have molecular weights of 29,500 and 25,500, respectively. The (alpha beta)3 and (alpha beta)4 structures were suggested for PCases G and P, respectively. On the basis of two-dimensional gel electrophoresis, the alpha and beta polypeptides of PCase-G differed from those of PCase-P. Amino acid analysis supported this conclusion. Both PCases, however, had several other properties in common. It is proposed that both isoenzymes were generated from different sets of alpha and beta subunits, and the significance of these data is discussed.     

Occurrence of parasites in Cobitidae from Croatian rivers draining into two different watersheds

Members of the Cobitidae family are not economically important, thus few studies have been made on their pathology. A survey of parasitic fauna of some representatives of the loaches, such as Cobitis elongata , C. elongatioides, and the recently described C. bilineata, was carried out during the spring and summer of 2006. Fish samples were collected from four Croatian rivers: the Sava, Drava and Kupa draining into the Danubian system, and the Zrmanja draining into the Adriatic system. Specimens were of varying size, weight and age. Ectoparasitological examination revealed infections by the ciliate parasites Trichodina nigra (61; 29%), Epistylis sp. (12; 9%), Chilodonella cyprinid (22; 58%), Ichthyophthyrius multifiliis (81; 81%), dinoflagellate Piscioodinium pillulare (6; 45%) and monogenean Gyrodactylus cobitis (22; 22%). Histopathological examination of haematoxylin-eosin stained tissues showed the presence of Sarcocystis sp. in the muscle of one specimen. Dissections revealed an isolated finding of plerocercoid of Ligula colymbi in a Drava river specimen. A more comprehensive survey is necessary to determine the actual threat of the parasitoses to endangered species of the Cobitidae family.     

Effects of photoperiod on pituitary gonadotropin levels in masu salmon

We examined the effects of photoperiod on pituitary levels of two types of gonadotropin (GTH), GTH I and GTH II, in masu salmon Oncorhynchus masou to study their mechanism of synthesis. In Experiment 1, the effects of long or short photoperiod combined with castration were examined using 8-month-old precocious males. Castration was carried out in early August and then the fish were reared under a short (8L16D) or long (16L8D) photoperiod for 60 days. In Experiment 2, the effects of photoperiod combined with testosterone treatment were examined using 12-month-old immature females. Silastic tubes containing testosterone (500 microg /fish) or vehicle were implanted intra-peritoneally in early October. Fish were reared under 16L8D for 60 days, and then half of the fish were transferred to 8L16D, while the remaining fish were kept under 16L8D until Day 90. In Experiment 1, GTH I contents were higher under 16L8D than under 8L16D in the castrated group on Day 30. Moreover, GTH I contents were higher in the castrated group than the control group under 16L8D on Day 30. GTH II contents increased with testicular maturation in the control groups, whereas they remained at low levels in the castrated groups regardless of photoperiodic treatment. In Experiment 2, GTH I contents did not change remarkably in all the groups, while GTH II contents were remarkably increased by testosterone treatment regardless of photoperiodic treatment. These results indicate that the synthesis of GTH I and GTH II are differently regulated by photoperiod and testosterone in masu salmon.     

Occurrence of Atlantic salmon parr in redds at spawning time

Several Atlantic salmon parr of different sizes were found alive in salmon redds under a 10–30 cm layer of stones at spawning time. Parr, both mature and immature, remain inactive in redds during daylight but show nocturnal activity.     

Ontogeny of pituitary cell-types and the hypothalamo-hypophysial relationship during early development of chum salmon,Oncorhynchus keta

Tissue non-specific alkaline phosphatase is a membrane-bound glycoprotein enzyme which is characterized by its phosphohydrolytic, protein phosphatase, and phosphotransferase activities. This enzyme is distributed virtually in all mammalian tissues, particularly during embryonic development. Its expression is stagespecific and can be demonstrated in the developing embryo as early as the 2-cell stage. It has been suggested that tissue non-specific alkaline phosphatase might play a role in tissue formation. In the study reported here, a genetransfer approach was employed to investigate possible roles for this enzyme by inserting the cDNA for rat tissue non-specific alkaline phosphatase into CHO and LLC-PK1 cells. Permanently transfected cell-lines expressing varying levels of alkaline phosphatase were estblished. The data showed that functional enzyme was expressed in the transfected cells. Cell spreading and attachment were enhanced in transfected CHO cells expressing high levels of tissue non-specific alkaline phosphatase but not in the LLC-PK1 cells. Further, in CHO cells, proliferation was shown to be inversely proportional to the level of the tissue non-specific alkaline phosphatase expression. Homotypic cell association was demonstrated in both alkaline phosphatase-positive and alkaline phosphatase-negative cells in both CHO and LLC-PK1 celllines. Taken together, these findings suggest that in addition to a role in mineralization of bone, tissue nonspecific alkaline phosphatase might also play a role in other cell activities, including those related to differentiation, such as cell-cell or cell-substrate interaction and proliferation.     

Transport of physiologically active salmon gonadotropin into the circulation in goldfish,following oral administration of salmon pituitary extract

Summary Salmon pituitary gland extract was orally administered to goldfish. The resulting transport of gonadotropin (GtH) into the blood plasma and its biological activities were investigated.Plasma levels of salmon GtH assayed by radio-immunoassay increased acutely and reached maximum levels as early as 6 h after oral administration, when administered with phosphate buffer (PB) or 0.2% polyacrylic acid (PAA) gel bases. The sharp rise in salmon GtH was not observed when the pituitary extract was administered with 1% PAA. The changes occurred more slowly, and the plasma levels of GtH were lower than those of PB or 0.2% PAA groups. Plasma levels of goldfish GtH did not increase.The absorbed salmon GtH was found to retain its biological activities. Plasma levels of testosterone increased in proportion with GtH absorption, except in the 1% PAA group. Elevated plasma 17,20-dihydroxy-4-pregnen-3-one levels were also observed in the PB group. Milt production increased within the first 24 h after the administration of pituitary extract.When the pituitary extract was administered in 1% PAA, the period in time in which the absorbed GtH remained elevated was noticeably longer than when given with 0.2% PAA or PB.Abbreviations BSA bovine serum albumin - GtH gonadotropic hormone - PAA polyacrylic acid - 17,20-diOH P 17,20-dihydroxy-4-pregnen-3-one - PB phosphate buffer - RIA radioimmunoassay - ANOVA analysis of variance - SEM standard error of mean     

Genomic and phenotypic effects of inbreeding across two different hatchery management regimes in Chinook salmon

Genomic approaches permit direct estimation of inbreeding and its effect on fitness. We used genomic‐based estimates of inbreeding to investigate their relationship with eight adult traits in a captive‐reared Pacific salmonid that is released into the wild. Estimates were also used to determine whether alternative broodstock management approaches reduced risks of inbreeding. Specifically, 1,100 unlinked restriction‐site associated (RAD) loci were used to compare pairwise relatedness, derived from a relationship matrix, and individual inbreeding, estimated by comparing observed and expected homozygosity, across four generations in two hatchery lines of Chinook salmon that were derived from the same source. The lines are managed as “integrated” with the founding wild stock, with ongoing gene flow, and as “segregated” with no gene flow. While relatedness and inbreeding increased in the first generation of both lines, possibly due to population subdivision caused by hatchery initiation, the integrated line had significantly lower levels in some subsequent generations (relatedness: F₂–F₄; inbreeding F₂). Generally, inbreeding was similar between the lines despite large differences in effective numbers of breeders. Inbreeding did not affect fecundity, reproductive effort, return timing, fork length, weight, condition factor, and daily growth coefficient. However, it delayed spawn timing by 1.75 days per one standard deviation increase in F (~0.16). The results indicate that integrated management may reduce inbreeding but also suggest that it is relatively low in a small, segregated hatchery population that maximized number of breeders. Our findings demonstrate the utility of genomics to monitor inbreeding under alternative management strategies in captive breeding programs.     

Occurrence of two different forms of protocatechuate 3,4-dioxygenase in a Moraxella sp.

Two alternative forms of protocatechuate 3,4-dioxygenase (PCase) have been purified from Moraxella sp. strain GU2, a bacterium that is able to grow on guaiacol or various other phenolic compounds as the sole source of carbon and energy. One of these forms (PCase-P) was induced by protocatechuate and had an apparent molecular weight of 220,000. The second form (PCase-G) was induced by guaiacol or other phenolic compounds, such as 2-ethoxyphenol or 4-hydroxybenzoate. It appeared to be smaller (Mr 158,000), and its turnover number was about double that of the former enzyme. Both dioxygenases had similar properties and were built from the association of equal amounts of nonidentical subunits, alpha and beta, which were estimated to have molecular weights of 29,500 and 25,500, respectively. The (alpha beta)3 and (alpha beta)4 structures were suggested for PCases G and P, respectively. On the basis of two-dimensional gel electrophoresis, the alpha and beta polypeptides of PCase-G differed from those of PCase-P. Amino acid analysis supported this conclusion. Both PCases, however, had several other properties in common. It is proposed that both isoenzymes were generated from different sets of alpha and beta subunits, and the significance of these data is discussed.     

Fish pituitary gonadotropins. Characteristics of salmon gonadotropic hormones

This review presents an attempt to systematize the fish gonadotropin investigations data, particularly concerning salmons. The common characterization of pituitary glycoprotein hormones of Vertebrata is presented. A brief review of the history of investigating fish gonadotropins is given. Immunological properties, subunit composition, carbohydrate component and gonadotropin receptors are described. The sequence data comparison and analysis are presented.