Sodefrin: a female-attracting peptide pheromone in newt cloacal glands

A decapeptide called sodefrin was isolated from the abdominal gland of the cloaca of the male red-bellied newt, Cynops pyrrhogaster. The native peptide, as well as the synthetic one, had a female-attracting activity. Sodefrin was found in the apical portion of the epithelial cells of the abdominal gland. Sodefrin is apparently species specific because it did not attract females of Cynops ensicauda. This is the first amphibian pheromone to be identified and the first peptide pheromone identified in a vertebrate.

Induction from posterior hypothalamus is essential for the development of the pituitary proopiomelacortin (POMC) cells of the toad (Bufo japonicus)

The role of the posterior hypothalamus in the development of the epithelial hypophysis was studied in Bufo embryos. In animals from which the central part of the neural plate (NP) had been surgically removed at the open neurula stage, the infundibulum did not develop, and the epithelial hypophysis was formed away from the normal site without morphological connection with the brain. Immunoreactive MSH cells and ACTH cells, i.e., the pituitary POMC cells, were not detected in any of the surgically treated animals, while other types of secretory cells (PRL, GH, TSH and GTH cells) were invariably present. In view of the fact that POMC cells originate in the anterior neural ridge, and not in the neural plate, the embryonic brain seems to exert an inductive influence upon the primordial pituitary POMC cells. Since these cells differentiate in a tail graft, isolated from the brain at a later stage (tail-bud stage), the inductive stimuli must be conveyed from/via the posterior hypothalamus to the pituitary anlage between the open neurula and the tail-bud stages.

The relationship between the expression of proliferating cell nuclear antigen and clinicopathological variables of gastric-cancer

A monoclonal antibody against proliferating cell nuclear antigen (PCNA), PC10, was applied to 96 gastrectomy specimens obtained from patients with gastric cancer. Resected tissue was routinely processed and stained immunohistochemically with PC10. One thousand tumor cells were counted and the ratio of the number of stained cells to total tumor cells was calculated as the PCNA index, which ranged from 13.8% to 88.8% with a mean of 61.4%. Although the PCNA index did not correlate with pathological variables including histological type, lymph node metastasis, growth pattern and venous invasion, it was significantly lower in mucosal carcinomas compared with submucosal and advanced carcinomas.

Analysis of lung surfactant in the metamorphosing bullfrog (Rana catesbeiana)

In bullfrog (Rana catesbeiana) tadpoles, the lung begins to function at an advanced stage of metamorphosis. As a preliminary step for investigation of the mechanisms involved in lung maturation, pulmonary surfactant was prepared from tadpoles at advanced stages of metamorphosis and its biochemical properties were analyzed. Surfactant phospholipid analysis revealed that the major constituent was phosphatidylcholine (PC), as examined in the animals at late climax (stage 24). Other detectable phospholipids were phosphatidylethanolamine, phosphatidylserine, sphingomyelin, and phosphatidylglycerol, a marker lipid in mammalian surfactant. As in mammals, PC in the surfactant was rich in saturated fatty acids, about 50% of fatty acid moieties being palmitic acid. The content of surfactant PC in the lung increased moderately around mid-climax and markedly at the end of climax. The effect of antiserum against bullfrog prolactin (PRL) on the pulmonary surfactant was studied in climactic tadpoles. The content of surfactant PC in the lung of the antiserum-treated larvae was lower than that in the lung of the normal rabbit serum-injected larvae, whereas the content of PC in the whole lung did not differ between the antiserum-treated and control groups. The results suggest that synthesis of surfactant in the amphibian lung is enhanced as metamorphosis progresses and that PRL is involved in lung maturation.

Seasonal changes of plasma prolactin concentration in the reproduction of the crested newt (Triturus carnifex Laur)

Plasma prolactin (PRL) and vitellogenin (VTG) concentrations were determined during the annual reproductive cycle of the newt Triturus carnifex Laur. Plasma PRL was measured by a radioimmunoassay using purified newt (Cynops pyrrogaster) PRL as standard and radioligand and its antibodies. Using ELISA, plasma VTG titers were related to ovarian weight. The trends in PRL differed in the two sexes: the PRL changes seemed to be related with vitellogenic processes in the female, whereas they were more related to reproductive behavior in the male.

Endogenous Substrates for Energy Metabolism in Spermatozoa of the Sea Urchins Arbacia lixula and Paracentrotus lividus

Energy metabolism was examined in the spermatozoa of the sea urchins Arbacia lixula and Paracentrotus lividus, which belong to the orders Arbacioida and Echinoida respectively. P. lividus spermatozoa contained various phospholipids and cholesterol, and their endogenous triglyceride (TG) content was quite low. After dilution of dry sperm in artificial seawater, the level of phosphatidylcholine (PC) decreased rapidly, but other phospholipids remained at constant levels. In contrast to those of P. lividus, the spermatozoa of A. lixula contained TG as well as phospholipids and cholesterol. Following incubation of A. lixula spermatozoa in artificial seawater, TG decreased, but there were no concomitant changes in the levels of phospholipids. Trace amounts of glycogen were present in both species. High lipase activity was demonstrated in A. lixula spermatozoa, but in P. lividus spermatozoa lipase activity was low and phospholipase A2 activity was high. It is thus concluded that A. lixula spermatozoa obtain energy for swimming through oxidation of endogenous TG, whereas P. lividus spermatozoa use PC as a substrate for energy metabolism. This suggests that the system of energy metabolism in spermatozoa is different in the orders Arbacioida and Echinoida.

Seasonal changes in plasma growth hormone and prolactin concentrations of the frog Rana esculenta

Plasma growth hormone (GH), prolactin (PRL), and vitellogenin (VTG) concentrations were determined during the annual reproductive cycle of the frog Rana esculenta. Plasma GH and PRL were measured using a RIA that employed purified bullfrog (Rana catesbeiana) GH and PRL as standards and radioligand, and their respective antibodies. Using ELISA, plasma VTG titers were related to ovarian weight. GH, PRL, and VTG displayed different trends related to season and sex. In male frogs the GH and PRL trends have been found parallel, showing the highest concentrations (35 and 85 ng/ml, respectively) during the winter months. In the female frogs, the GH trend behaved differently from that in males; in fact, plasma GH changed during the annual reproductive cycle, showing two main peaks occurring during the reproductive period and the autumn ovarian recrudescence that are well correlated with the vitellogenesis as well as with the main changes in ovarian weight.

Hormonal control of response to and secretion of sex attractants in Japanese newts

Hormonal control of sexual chemoattraction in the newt, Cynops pyrrhogaster, was investigated by a water preference test. Sexually inert newts injected with prolactin (PRL) and human chorionic gonadotropin (HCG) in combination preferred the water in which newts of the opposite sex had been kept, whereas saline-injected specimens did not. This indicates that PRL and HCG enhance the response of the newts to attractant(s) secreted by the opposite sex. The water in which PRL plus HCG-treated newts had been kept attracted the opposite sex more intensely than the water in which PRL-, HCG-, or saline-injected newts had been kept. In castrated males, PRL plus testosterone propionate (TP), and in ovariectomized females, PRL plus estradiol induced the secretion of substance(s) that attracted newts of the opposite sex. Removal of the abdominal gland of the cloaca in the male or the oviduct in the female attenuated the attracting activity of the water in which they were kept. Involvement of PRL and gonadal steroids in the secretion of sex attractants by the male abdominal gland and female oviduct was suggested.

Cloning of a toad prolactin cDNA: expression of prolactin mRNA in larval and adult pituitaries

A toad (Bufo japonicus) prolactin cDNA was specifically amplified from cDNAs constructed from the total RNA of adenohypophyses, employing the DNA polymerase chain reaction. Sequencing analysis revealed that the cDNA clone thus obtained was 602 bp in length, and encoded the C-terminal 134 amino acid residues of the toad prolactin molecule. The length of the toad prolactin mRNA was estimated to be about 1.0 kb by Northern blot analysis. The partial amino acid sequence deduced from the nucleotide sequence showed the following homologies between toad prolactin and the prolactins of other vertebrates: 69% with man, 80% with chicken, 81% with sea turtle, 91% with bullfrog and 38% with salmon. Using the cDNA as a probe, developmental and seasonal changes in prolactin mRNA levels in the pituitaries of toads were studied. Prolactin mRNA in the pituitary rose as metamorphosis progressed and declined at the end of metamorphosis. During the breeding season the pituitary content of prolactin mRNA was relatively high. This finding suggests that the increases in plasma and pituitary prolactin levels in larvae at metamorphic climax and in adults that remain in or migrate into water, as reported previously, accompany the increase in prolactin synthesis.

Hormonal induction of male courtship behavior in the Japanese newt, Cynops pyrrhogaster

In the breeding season, the sexually mature male newt, Cynops pyrrhogaster, vibrates the tail in front of the female at an early stage of courtship. Effects of prolactin (PRL), gonadotropin (GTH), and sex steroids on this behavior were investigated in the male paired with the female receiving PRL and GTH. The behavior was elicited in the sexually inert male by injections of PRL of bovine, ovine, or bullfrog origin and human chorionic gonadotropin or bullfrog LH and FSH in combination. The effect of PRL or GTH alone was less marked than that of PRL plus GTH, especially in terms of frequency of the behavior. In the hypophysectomized male, combination of PRL and GTH significantly increased both the incidence and frequency of the behavior. However, PRL alone was not effective, and the effect of GTH alone was less pronounced than that in the intact animal receiving GTH injections. The effect of GTH was nullified by castration. In the PRL-treated castrated animal, testosterone or dihydrotestosterone, but not estradiol, was effective in inducing the behavior.

Immunocytochemical identification of growth hormone (GH) cells in the pituitary of three anuran species using an antiserum against purified bullfrog GH

An antiserum was prepared against the recently purified bullfrog (bf) growth hormone (GH); it was applied to sections of brain and pituitary of three urodele (Ambystoma, Pleurodeles and Cynops) and three anuran (Xenopus, Bufo vulgaris and B. japonicus) species. No immunostaining was obtained in the urodele pituitary, being consistent with the results of immunoblot analysis of the pituitary homogenate. In the three anuran species, strong immunoreactivity was observed in GH cells that were concentrated in the posterodorsal region of the pars distalis. No GH-like immunoreactivity was detectable in the brain of any of the species. A comparison using adjacent sections stained with anti-bf prolactin (PRL) confirmed the anteroventral localization of PRL cells. Colocalization of GH and PRL was not apparent. These data suggest that the molecular structure of amphibian GHs is considerably different between anurans and urodeles. The antiserum used in the present work shows a high species specificity, recognizing only anuran GHs. In contrast anti-bfPRL labeled PRL cells in all the amphibian species studied in the present work, suggesting that PRLs possess common amino acid sequences recognized by the anti-bfPRL.

Isolation and characterization of two forms of Xenopus prolactin

Two forms of highly purified prolactin (PRL) were obtained from pituitary glands of Xenopus laevis by extraction of acetone-dried powder with acid acetone and high-performance liquid chromatography on anion exchange, gel filtration, and reverse-phase columns. Purification was monitored by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis employing antiserum against bullfrog PRL. The Xenopus prolactins (xPRL-I and xPRL-II) thus obtained were shown to have similar molecular weights of 23,000 as determined by SDS-PAGE. The isoelectric points of xPRL-I and xPRL-II determined by isoelectric focusing were 5.6 and 5.3, respectively. Both hormones blocked T4-induced shrinkage of Xenopus tadpole tail fin in vitro. The amino acid compositions of the xPRLs resembled that of bullfrog PRL. The partial amino acid sequences of xPRL-I and of xPRL-II showed 78 and 68% homology with the comparable portion of the sequence of bullfrog PRL, respectively. Homology between xPRL-I and xPRL-II was 90%.

Development of the ectopically transplanted primordium of epithelial hypophysis (anterior neural ridge) in Bufo japonicus embryos

It has recently been demonstrated that the epithelial pituitary of the toad is not stomodeal, but placodal, in origin. The placodal cells in the anterior part of the neural ridge (ANR) of the open neurulae are the exclusive source of the epithelial pituitary gland. The present study was undertaken to see the self-differentiating ability of these cells in an ectopic environment. Bufo japonicus embryos at the tailbud stage received implants of either the ANR from open-neurula-stage embryos, or the pituitary primordium from tailbud-stage embryos (the ANR derivative beneath the forebrain floor) into the tail. Development of the pars intermedia and the pars distalis was monitored immunohistochemically using antisera against both synthetic alpha melanophore-stimulating hormone (alpha MSH) and bullfrog prolactin (PRL). Neither the immunoreactive alpha MSH cells nor the immunoreactive PRL cells differentiated from the neural ridge when it was dislocated from the original site at the open neurula stage. On the other hand, in grafts of the pituitary primordium transplanted from the tailbud-stage embryos, immunoreactive PRL cells developed invariably and immunoreactive alpha MSH cells were detected at an incidence of 72%. The significance of the role of brain tissue surrounding the pituitary anlage in differentiation of the pars intermedia and pars distalis is discussed.

In-vitro effects of mammalian and amphibian prolactins on hepatic vitellogenin synthesis in Rana esculenta

Male and female Rana esculenta liver was induced in an in-vitro system by homologous and Rana catesbeiana pituitary to synthesize and release vitellogenin, a lipoglycophosphoprotein precursor of yolk proteins, lipovitellins and phosvitins, in oviparous vertebrates. In the present experiments, the action of prolactin on hepatic vitellogenin synthesis and release was investigated, using ovine prolactin and Rana catesbeiana prolactin. The effects of prolactin on hepatic vitellogenin synthesis displayed different trends related to sex; male liver was found to be more responsive than female liver to both ovine and frog prolactin; more-over, the response to prolactin was dose-related (r = 0.998; P < 0.05) in male but not in female liver. In both sexes, a high degree of seasonality in the responsiveness of the liver was found, since the vitellogenin levels induced by prolactin during the winter phase were significantly (P < 0.001) higher than those produced during the summer phase. Thus, there was no significant difference between the action of ovine and frog prolactin on vitellogenin synthesis; in fact, mammalian prolactins are structurally similar with regard to nucleotide and amino acid sequences. The direct action of prolactin on hepatic vitellogenin synthesis in the frog Rana esculenta is discussed, on the basis of the role played by prolactin as an important growth modulatory hormone in fetal and adult tissues.

Immunocytochemical localization of atrial natriuretic factor (ANF)-like peptides in the brain and heart of the treefrog Hyla japonica: effect of weightlessness on the distribution of immunoreactive neurons and cardiocytes

The localization of atrial-natriuretic factor (ANF)-like immunoreactivity was investigated in the brain and heart of the treefrog Hyla japonica by the indirect immunofluorescence technique. Concurrently, the effect of weightlessness on the distribution of ANF-containing neurons and cardiocytes was studied in frogs that were sent into space for 9 days on the space station "MIR." In control animals, the amygdala contained the most prominent group of ANF-immunoreactive cells and fibers. ANF-positive neurons and nerve processes were also detected in other areas of the telencephalon such as the nucleus olfactorius, the pallium mediale, and the striatum. In "space frogs," the intensity of labeling of the amygdala and nucleus olfactorius was similar to that seen in control animals. In contrast, the pallium and the striatum of "space frogs" were totally devoid of positive cell bodies. In the diencephalon, of all animals, numerous ANF-immunoreactive perikarya and fibers were seen in the hypothalamus, the anterior thalamus, the infundibulum, and the median eminence. ANF-positive cell bodies were also noted in the lateral forebrain bundle of control frogs but were absent in "space frogs." The major difference between control and "space frogs" was observed in the posterior nuclei of the thalamus. In "space frogs," the nucleus posterocentralis thalami and the nucleus posterolateralis thalami exhibited large ANF-immunoreactive perikarya, while, in control frogs, these nuclei only contained scarce positive nerve fibers. In the mesencephalon, ANF-positive cell bodies and nerve processes were seen in the nucleus tegmenti mesencephali, the interpeduncular nucleus, and the nucleus cerebelli of all animals. However, stained perikarya were only observed in the nucleus reticularis isthmi of control frogs. In the heart, atrial cardiocytes exhibited intense ANF-like immunoreactivity. ANF-positive myocytes were also detected in the subpericardial region of the ventricle. The density and distribution of the staining were identical in the heart of control and "space frogs." These data support the concept that prolonged exposure to microgravity affects biosynthesis and/or release of ANF-related peptides in discrete regions of the amphibian brain.

An additional arginine-vasotocin-related peptide, vasotocinyl-Gly-Lys, in Xenopus neurohypophysis

The neurohypophysis of Xenopus and that of Ranidae and Bufonidae contain hydrin 1 (vasotocinyl-Gly-Lys-Arg) and hydrin 2 (vasotocinyl-Gly), respectively. In order to test the aldosterone-releasing activity of arginine vasotocin (AVT) and hydrin 1, purification of these peptides from an acid-extract of the neurointermediate lobe of Xenopus laevis was performed using an ODS-silica cartridge and reverse-phase and ion-exchange HPLC columns. As a result, an additional AVT-related peptide was newly found. Amino-acid analysis revealed that this peptide is vasotocinyl Gly-Lys (AVT-GK). The aldosterone-releasing activity of AVT-GK was equivalent to that of hydrin 1 (AVT-GKR) and lower than that of AVT. Like AVT and AVT-GKR, AVT-GK were effective in stimulating water flux from the isolated urinary bladder of the toad. Since AVT-GK is regarded as an intermediate between hydrin 1 and hydrin 2 in terms of its C-terminal form, it was designated hydrin 1'.

Lymphangioma of the jejunal mesentery in an adult: a case report and a review of the Japanese literature

A rare case of lymphangioma of the jejunal mesentery in a 34-year-old woman is presented. She was diagnosed as having an ovarian cyst preoperatively, but laparotomy revealed a cystic tumor of the mesentery that was histologically diagnosed as lymphangioma. Thus far, 44 cases of adult mesenteric lymphangioma have been reported in Japan. In nine cases, accurate diagnosis of mesenteric cysts was obtained preoperatively. In 31 cases, complete excision with or without bowel resection was done, whereas two cases were partially resected and one case was drained.

Immunocytochemical and ultrastructural study of Rana dalmatina PRL and GH pituitary cells during larval development

Single and double simultaneous indirect immunogold methods and ultrathin sagittal sections of Rana dalmatina tadpole heads were used to follow cytodifferentiation of PRL and GH cells in the adenohypophysial primordium from developmental stage 26 to the end of metamorphosis. Rabbit anti-frog (Rana catesbeiana) PRL and rabbit anti-frog GH were employed in the single method, and rabbit anti-frog PRL and monkey anti-rat GH were used in the double simultaneous technique as primary antisera. At stage 27, a couple of cells with few small secretory granules immunoreactive with anti-frog GH are first identifiable. At stage 28, some cells with few membrane-bound secretory granules, 70-90 nm in diameter, and immunoreactive with anti-frog PRL and other cells with few secretory granules, 80-110 nm in diameter, and immunoreactive with anti-frog GH are present. As development progresses, differentiation in both cell types is shown by an increase in the cytoplasmic volume and in the number, size, and immunoreactivity of secretory granules. Neither comparison of adjacent ultrathin sections stained with the single labeling technique nor results of double simultaneous labeling showed the coexistence of PRL and GH within the same cell.

Binding of aldosterone by epidermal cytosol in the tail of bullfrog larvae

Characteristics of aldosterone binding by epidermal cytosol in the tail of the larval bullfrog were investigated. Temperature-dependent binding experiments showed that the specific binding of [3H]aldosterone to the tail cytosol was thermolabile. A 3-hr incubation at 0 degrees was the optimum assay condition required for reaching equilibrium. Separation of bound and free hormone was performed using a hydroxylapatite method. Specific binding of aldosterone was observed in the tail epidermis but not in the tail mesenchyme. Saturation analysis revealed that specific binding of [3H]aldosterone to the epidermal cytosol reached maximum between 20 and 40 nM. Scatchard analysis for the cytosol of the tail epidermis yielded a straight line with a dissociation constant (Kd) of 7.0 nM and the maximum number of binding sites (Bmax) of 56.4 fmol/mg protein. Sucrose density gradient analysis of crude cytosol revealed a specific peak of radioactivity in the 8-9 S area. Steroid-binding specificity revealed a significant displacement of the [3H]aldosterone by radioinert aldosterone and, to a lesser extent, by cortisol, whereas 17 beta-estradiol and testosterone competed very poorly. However, corticosterone and dexamethasone, glucocorticoids in mammals, were better competitors of the aldosterone binding, whereas ZK91587, a selective synthetic antagonist for mineralocorticoid receptor in mammals, scarcely inhibited the aldosterone binding. These results suggest that the aldosterone-binding site may also be a corticosterone receptor and that there may be no other receptors specific for aldosterone at least in the tail epidermis.

Thyrotropin-releasing hormone (TRH) is the major prolactin-releasing factor in the bullfrog hypothalamus

A substance exhibiting potent activity in stimulating the release of prolactin from bullfrog (Rana catesbeiana) pituitary in vitro was isolated from an acid extract of bullfrog hypothalami by gel-filtration chromatography (Sephadex G-15), ion-exchange chromatography (Mono-S HR 5/5), and reverse-phase high-performance liquid chromatography (TSK-gel ODS-120T). Its amino acid composition was similar to that of synthetic thyrotropin-releasing hormone (TRH). Radioimmunoassay confirmed that the substance had TRH immunoreactivity. Moreover, it exhibited the same chromatographic behavior as that of synthetic TRH. These results clearly indicate that the isolated hypothalamic substance is TRH, and that it is the major prolactin-releasing factor present in the bullfrog hypothalamus.

Cloning of a bullfrog growth hormone cDNA: expression of growth hormone mRNA in larval and adult bullfrog pituitaries

A GH cDNA was specifically amplified from cDNAs constructed from total RNA of bullfrog (Rana catesbeiana) adenohypophyses employing the DNA polymerase chain reaction. Sequencing analysis revealed that the cDNA clone thus obtained was 654 bp in length, and included an open reading frame encoding the entire sequence of mature GH, with its signal peptide. Slight discrepancies were noted between the deduced amino acid sequence and that determined by direct protein sequencing of purified bullfrog GH or that deduced from the nucleotide sequence reported previously. The length of the bullfrog GH mRNA was estimated to be about 1.2 kb by Northern blot analysis. Homologies of nucleotide and amino acid sequences between GH and prolactin of bullfrog origin were 48% and 26% respectively. Using the cDNA as a probe, the content of GH mRNA in the pituitary of larval and adult bullfrogs was measured. GH mRNA levels were relatively low at the preclimax stage, and rose markedly during climax. In juvenile frogs, GH mRNA levels in the pituitary were extremely high and declined towards adulthood. This finding suggests that the increase in plasma and pituitary GH levels reported previously accompanies the increase in GH synthesis.

Hormonal control of in vitro vitellogenin synthesis in Rana esculenta liver: effects of mammalian and amphibian growth hormone

Estradiol 17-beta is known to induce hepatic synthesis and secretion of vitellogenin in all species studied and in Rana esculenta, previous experiments demonstrated the involvement of pituitary in these processes; indeed, in addition to estradiol 17-beta, homologous pituitary homogenate directly stimulated male and female liver to produce vitellogenin in tissue cultures. Therefore, the effect of ovine growth hormone (o-GH) and Rana catesbeiana growth hormone (f-GH) on hepatic vitellogenin synthesis was investigated. In the present in vitro experiments, both o-GH and f-GH positively stimulated vitellogenin synthesis, in female and male liver, in a dose-related fashion. No significant differences were found in VTG levels induced by o-GH and f-GH. The GH stimulatory effects, found during the different phases of the reproductive cycle, displayed different trends related to season and sex.