Stanniocalcin-like immunoreactivity in the corpuscles of Stannius of the bowfin Amia calva L.

Summary We used an antiserum against salmon stanniocalcin in an immunohistochemical, immunocytochemical, and Western blot analysis of bowfin (Amia calva) corpuscles of stannius. The bowfin is one of two extant holostean species with ancient ancestral links to modern-day bony fishes. The corpuscles of Stannius (white corpuscles) of the bowfin were scattered throughout much of the kidney among the adrenocortical homolog (yellow corpuscles) but could be distinguished from the adrenocortical homolog by their positive staining with both the periodic acid-Schiff reaction and a salmon stanniocalcin antiserum. Immunoreactivity was confined to cytoplamic granules and was absent when the antiserum was blocked with salmon stanniocalcin or with a crude extract of bowfin corpuscles of Stannius. When bowfin corpuscle-of-Stannius extracts were subjected to sodium dodecyl sulphate electrophoresis and Western blot analysis, two closely spaced bands were evident (43–45 kDa). Staining of both bands was abolished by pre-absorption of the antiserum with salmon stanniocalcin. In comparison to salmon stanniocalcin, the reputed bowfin hormone migrated faster in gels, suggesting a smaller apparent size. The purification of bowfin stanniocalcin should yield important new information regarding the evolution of this unique calcium-regulating hormone.     

Corpuscles of Stannius and stanniocalcin-like immunoreactivity in the white sucker (Catostomus commersoni): evidence for a new cell-type

The distribution of stanniocalcin immunoreactivity was examined in the corpuscles of Stannius of the white sucker (Catostomus commersoni) by using a chum salmon stanniocalcin antiserum, Western blotting, and light and electron microscopy. The white sucker possesses at least two stanniocalcin-immunoreactive corpuscles in the most posterior portions of the kidneys. Immunocytochemistry and ultrastructure revealed two cell-types in the corpuscle parenchyma, only one of which was immunoreactive. The nonimmunoreactive cells contained dense-cored vesicles and long processes that extended between the immunoreactive cells and terminated at perivascular spaces. When corpuscle extracts were subjected to electrophoresis and Western blotting, three nonreduced stanniocalcin-like immunoreactive bands (approximately 56, 61, and 64 kDa) were observed. However, in the presence of a reductant, a diffuse band migrating in the range of 28 to 32 kDa was noted. The results of this study on the white sucker demonstrate the presence of a dimeric stanniocalcin-like molecule and present evidence of a previously uncharacterized cell-type in the corpuscles of Stannius.     

Immunoreactivity of the corpuscles of Stannius of the garpike,Lepisosteus osseus,to antisera against salmon and trout stanniocalcins

Stanniocalcin-immunoreactive cells were localized in the corpuscles of Stannius of a holostean fish, the garpike (Lepisosteus osseus), using antisera against salmon and trout stanniocalcins and the peroxidase-antiperoxidase and protein A-gold immunohistochemical methods. The stanniocalcin-immunoreactive cells were periodic acid-Schiff-positive, and antibody staining was abolished if the antiserum was preabsorbed with corpuscle homogenate. Immunocytochemistry revealed two reactive cell types in the glandular parenchyma, and immunoreactivity was confined to the secretory granules. Staining of the granules was also abolished when the antisera were blocked with crude corpuscle homogenate. When corpuscle extracts from garpike were subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot analysis, a single dense band was evident with a molecular weight of 68 kDa under non-reducing conditions, whereas three bands were observed (29, 31, and 34 kDa) under reducing conditions. Staining of all bands disappeared following preabsorption of the antiserum with salmon stanniocalcin, trout stanniocalcin, or garpike corpuscle extract. The results are compared with stanniocalcins from another extant holostean, the bowfin (Amia calva), and from more modern bony fishes, the teleosts.     

Chum salmon (Oncorhynchus keta) stanniocalcin inhibitis in vitro intestinal calcium uptake in Atlantic cod (Gadus morhua)

Summary Chum salmon (Oncorhynchus keta) stanniocalcin was purified, partially identified and tested for bioactivity in an assay on the intestinal calcium uptake in a marine teleost (Gadus morhua). Basic ethanol extraction, ion exchange chromatography, gel filtration and reverse-phase high-performance liquid chromatography resulted in the isolation of a homogenous glycoprotein that appears as a 46-kDa product under non-reducing conditions and as a 23-kDa product under reducing conditions after sodium dodecylsulphate-polyacrylamide gel electrophoresis. The glycoprotein is likely to be a homodimer composed of two subunits of 23 kDa each. Further characterization indicates homology to Australian eel, sockeye salmon, coho salmon and rainbow trout stanniocalcin, and the glycoprotein is thus concluded to be stanniocalcin. Stanniocalcin-like immunoreactivity was demonstrated in the corpuscles of Stannius of the Atlantic cod, with a specific antiserum raised against purified chum salmon stanniocalcin. The physiological importance and the biological activity of chum salmon stanniocalcin was tested by evaluating its effect on intestinal calcium uptake by the Atlantic cod in vitro. The intestine was perfused, both vascularly and through the intestinal lumen, and the calcium mucosa-to-serosa flux was measured using ⁴⁵Ca²⁺ as a tracer. Stanniocalcin decreased the intestinal calcium uptake in a dose-related manner by 13.5% and 22.4% at doses of 2.2 and 10.9 nM stanniocalcin, respectively. The results establish the intestine as a target organ for stanniocalcin in marine teleosts.Abbreviations BIS balanced intestinal solution - CS corpuscles of Stannius - dpm disintegrations per minute - FW freshwater - J _in ^Ca influx of calcium across the intestinal mucosa - MW molecular weight - NRS normal rabbit serum - PBS phosphate buffered saline - PBST phosphate buffered saline containing 0.05% Tween-20 - PITC phenyl isothiocyanate - rp-HPLC reverse phase - SW seawater - STC phenyl isothiocyanate - rp-HPLC reverse phase - SW seawater - STC stanniocalcin - TFA Trifluoroacetic acid - Tris Tris(hydroxymethyl) aminomethan - V volume per fraction     

鱼类斯钙素的研究进展

本文概述了近年来有关硬骨鱼类斯坦尼氏小体（ｃｏｒｐｕｓｃｌｅｓｏｆＳｔａｎｎｉｕｓ,ＣＳ）分泌激素———斯钙素（ｓｔａｎｎｉｏｃａｌｃｉｎ,ＳＴＣ）的研究进展。ＳＴＣ是糖蛋白类激素,为同型二聚体,其表观分子量在天然状态下从４６（大麻哈鱼）～５６（虹鳟）ｋＤａ,还原状态下则为２３～２８ｋＤａ。ＳＴＣ单体的氨基酸序列分析表明,大麻哈鱼、银大麻哈鱼和澳大利亚鳗鲡的氨基酸残基数分别为１７９、２２３和２３１个。研究还表明,ＳＴＣ的分泌受血钙浓度的调节,并且胆碱能神经参与ＳＴＣ的释放。     

The murine stanniocalcin 1 gene is not essential for growth and development

The stanniocalcin 1 (STC1) gene is expressed in a wide variety of tissues, including the kidney, prostate, thyroid, bone, and ovary. STC1 protein is considered to have roles in many physiological processes, including bone development, reproduction, wound healing, angiogenesis, and modulation of inflammatory response. In fish, STC1 is a hormone that is secreted by the corpuscles of Stannius and is involved in calcium and phosphate homeostasis. To determine the role of STC1 in mammals, we generated Stc1-null mice by gene targeting. The number of Stc1-/- mice obtained was in accordance with Mendelian ratios, and both males and females produced offspring normally. No anatomical or histological abnormalities were detected in any tissues. Our results demonstrated that Stc1 function is not essential for growth or reproduction in the mouse.     

Immunocytochemical localization of hypocalcin in the endocrine cells of the corpuscles of Stannius in three teleost species (trout,flounder and goldfish)

Summary In order to identify the cell-type responsible for the production of hypocalcin (the recently isolated hypocalcemic hormone of teleost fish), the corpuscles of Stannius (CS) of trout, flounder and goldfish, were immunocytochemically stained with antisera raised against trout hypocalcin. The secretory granules of the type-1 cells of the CS, considered to be the hypocalcin-producing cells, showed intense immunoreactivity in all species examined. However, in trout and flounder, the secretory granules produced by the type-2 cells, which have been suggested to represent a functionally different cell-type, also showed an intense immunoreactivity. In goldfish, no type-2 cells were observed. We tentatively conclude that type-1 and type-2 cells represent structurally different forms of the same functional cell-type.     

Chromogranin A is present in and released by fish endocrine tissue

Chromogranin A (CgA) is a protein that is present in many mammalian endocrine cells and co-secreted with their resident hormones. We have demonstrated the presence of CgA by immunohistology in the ultimobranchial glands and corpuscles of Stannius of rainbow trout. CgA was also detected by radioimmunoassay in the medium of incubated coho salmon ultimobranchial glands. Our observations demonstrate the presence of CgA in endocrine glands of evolutionarily divergent species. These observations are consistent with the hypothesis that CgA participates in the secretory process of a wide variety of hormones.     

Fine Structure of the Adrenocortical Homolog and the Corpuscles of Stannius of Amia calva L.

A comparison is made between the fine structure of yellow corpuscles and white corpuscles located within the kidneys of the holostean fish, Amia calva L. The yellow corpuscles are composed of epithelial cells possessing all the features of steroid-producing tissues, namely an abundance of vacuoles, tubular smooth endoplasmic reticulum, and mitochondria with tubular cristae. The Golgi apparatus is also a conspicuous component of their cytoplasm. These cells are homologous to adrenocortical cells of higher vertebrates and they have cytoplasmic projections which extend into the lumina of surrounding sinusoids. The white corpuscles possess epithelial cells of variable appearance but all cells contain secretory granules and an extensive rough endoplasmic reticulum. The secretory granules appear to originate at the Golgi apparatus and occasionally are observed intact in the intercellular space. However the method of release of these granules was not clearly defined. These corpuscles are similar to the corpuscles of Stannius which have been described in modern bony fish. The presence of multivesicular bodies and smooth endoplasmic reticulum in some cells may reflect the origin of the corpuscles of Stannius from the tubular nephron. A. calva appears to be a suitable organism for comparative studies into the function of the adrenocortical homolog and corpuscles of Stannius in “primitive” fish.     

Development of the corpuscles of Stannius in the anabantid teleost, Colisa lalia

The development of Stannius corpuscles in the teleost Colisa lalia is described. Certain cells of the mesonephric tubules differentiate and proliferate to form buds which evaginate and finally become separated from the structure of origin. The separated cellular masses undergo further histologic differentiation to attain the adult structures. The corpuscles in C. laha, in contrast to some other teleosts, develop only from mesonephric tubules. A possible explanation for the different types of distribution of Stannius corpuscles in teleosts is suggested, and the possible homology of these structures with part of the adrenal cortex or higher vertebrates is discussed.     

Fine structure of the corpuscles of stannius in the toadfish.

The micro-anatomy of the corpuscles of Stannius of the toadfish, Opsanus tau, an aglomerular marine teleost, has been studied by light and electron microscopy. The corpuscles are composed of extensively anastomosed cords of epithelial cells which maintain intimate contact with blood capillaries. Most of the epithelial cells contain acidophilic granules which also show a positive reaction with the periodic acid-Schiff technique and aldehyde fuchsin. On the basis of fine structural criteria, three cell types can be recognized. The granular cells contain abundant quantities of granular endoplasmic reticulum, ribosomes, Golgi apparatus with prosecretory granules, coated vesicles, polymorphic mitochondria with lamellar cristae, filaments, microtubules, a cilium, a variety of lysosome-like dense bodies, glycogen particles, lipid droplets, secretory granules and intranuclear lipid-like inclusions. One variety of agranular cell (type I) is characterized by the total absence of secretory granules, but it contains large amounts of granular endoplasmic reticulum and ribosomes, conspicuous profiles of Golgi apparatus, coated vesicles and sometimes an abundance of glycogen. Another variety of agranular cell (type II) has poorly developed cytoplasmic organelles. The perivascular space between the capillary and parenchyma contains connective tissue cells and abundant nerve fibers. The different types of epithelial cells observed in the corpuscles of Stannius of this fish may represent functional stages of the secretory cycle in a single cell type.     

Immunohistochemistry of Grandry corpuscles in the oral mucosa of the duck bill: a light- and electron-microscopic study

Grandry corpuscles in the oral mucosa of the upper bill of the duck were immunohistochemically studied using antisera against calcitonin gene-related peptide (CGRP), galanin, methionine-enkephalin, neuropeptide Y (NPY), somatostatin, substance P (SP) and vasoactive intestinal peptide (VIP). Grandry corpuscles in the lamina propria selectively showed only SP-like immunoreactivity. Herbst corpuscles distributed near Grandry corpuscles were negative to all antisera applied. Although immunoreactive products in the Grandry corpuscles were found as granules in the peripheral cytoplasm of the Grandry cell, the axon terminals and satellite cells exhibited no reactivity. In pre-embedding electron-microscopic sections, SP-like immunoreactive products visualized with 3,3-diaminobezidine were localized in the granules of Grandry cells, but no labeling was observed in the cytoplasmic matrix or cell organelles. Electron-immunocytochemical labeling with colloidal gold by the post-embedding method clearly demonstrated that the SP antigen was localized only in the granules. It is presumed that Grandry cells have a secretory function. However, the function and the method of release of the SP contained in the observed granules remains obscure. Some CGRP-, NPY-, SP- and VIP-like-immunoreactive nerve fibers with varicosities associated with blood vessels and nerve fiber bundles of various sizes were observed in the lamina propria, but no such fibers penetrated into the intraepitherial layer. Nerve fibers positive for SP and VIP were also found in the interlobular connective tissue of the palatine glands. Some SP-positive neurons were detected in the vicinity of the palatine glands.     

Vascularization,innervation, and ultrastructure of the endocrine cell types of stannius corpuscles in the teleost Gasterosteus aculeatus

The blood circulation of the Stannius corpuscles, like that of the kidneys to which the corpuscles are attached, represents a portal system. The corpuscles receive blood from the dorsal caudal vein and from a vein coming from the hypaxial musculature. They are drained by veins which enter the caudal parts of the kidneys and therefore endocrine substances released by the corpuscles pass through the kidneys before they enter the general body circulation. The corpuscles are penetrated by sympathetic nerves coming from a small subvertebral ganglion. It is likely that these nerves innervate the muscular coat around the blood vessels. The muscular coat surrounding the renal blood vessels, the collecting tubules and part of the ureters, is innervated by nerves from the same ganglion. The secretory activity of the gland cells appears to be controlled by blood borne factors, because neither synaptic contacts with these cells, nor gap junctions among the cells, have been found in thin sections and freeze-etch replicas of the corpuscles. The corpuscles contain two cell types, both presumed to have endocrine function. Histochemical and ultrastructural data indicate that the gland cells produce glycoproteins. It is likely that the contents of the secretory granules are released by exocytosis. One cell type is structurally similar to the cells described in many other teleosts and thought to be engaged in the synthesis of a hypocalcemic hormone. The ultrastructure of the second cell type resembles cells described only in other migratory species: salmonids and eels. It may be involved in the control of monovalent ions.     

A second cell type in stannius bodies of two euryhaline teleost species

In the corpuscles of Stannius of sticklebacks and eels two cell types are described of presumably endocrine nature. The predominating type, comparable to the cells observed in other species, responds to variation in calcium content of the medium and possibly produces a hypocalcemic hormone. The second cell type is unreactive to calcium. Since it is more active in freshwater than in seawater specimens, this cell type is possibly involved in ionic regulation. It was not found in two seawater teleost species.     

Evidence of hypocalcemic factor from corpuscles of Stannius of the teleost Heteropneustes fossilis (Bloch)

The administration of acid extract of corpuscles of Stannius has no effect on the plasma calcium level, in the normal fish, whereas the same dose shows typical hypocalcemic response in hypercalcemic fish, H. fossilis. It is concluded that acid extract of corpuscles of Stannius is effective only in hypercalcemic condition.     

Differential Activity of Stanniocalcin in Male and Female Fresh Water Teleost Mastacembelus armatus (Lacepede) during Gonadal Maturation

The present study was carried out to analyze the differences in the activity of hormone stanniocalcin (STC) between male and female fishes of Mastacembelus armatus during their gonadal cycle. A large variation in nuclear diameter of cells of corpuscles of Stannius (CS) were recorded in relation to testicular cycle as well as ovarian cycle which indicates that the cellular activity varied with different phases of reproductive cycle in both male and female fish. Similar changes in nuclear diameter of CS cells were also observed after 17alpha-methyltestosterone administration in males and 17 β-estradiol administrations in females. A positive correlation was observed between plasma STC levels, gonadosomatic index (GSI) and the sex steroids in both sexes, suggesting that STC has a role in the processes involved in gonadal development. In addition females showed remarkable changes in plasma calcium level during gonadal cycle while no such change for males were observed. In females the plasma calcium level estimated during different phases of reproductive cycle indicates positive correlation between plasma level of calcium and gonad growth. Thus hyperactivity of CS cells was noted in both male and female fishes during gonadal cycle along with the differences in the activity of STC as well. In female it may act as hypocalcemic factor and bring the level of calcium to normal which increases during preparatory and pre spawning phases to fulfill the increased demand of calcium for vitellogenesis. However data of male fishes indicated that plasma STC concentration varied widely during gonadal cycle but showed no consistent relationship to plasma calcium level.     

Endocrine Control of Calcium Metabolism in Teleosts

It is evident that fishes regulate their serum calcium efficientlybut that endocrine systems involved may be different from thosein tetrapods. A functional parathyroid gland has not yet beendemonstrated in fishes. The majority of evidence indicates thatcalcitonin has little or no effect on fish calcium regulation.Instead, the corpuscles of Stannius and the pituitary glandare necessary for maintaining fish serum calcium levels. Inthe killifish, Fundulus heteroclitus, the removal of the corpusclesproduces hypercalcemia in sea water but not in artificial seawater deficient in calcium. Transplants of the corpuscles orthe administration of corpuscle homogenate corrects the increasein calcium. On the other hand, hypophysectomy elicits hypocalcemiaunder calcium deficient conditions but not in calcium rich seawater. Replacement therapy with pituitary homogenate or hypophysialtransplant prevents the fall in calcium. It is postulated thatthe hypocalcemic corpuscles of Stannius and the hypercalcemicpituitary gland enable the euryhaline killifish to regulateits serum calcium levels in high calcium sea water and low calciumfresh water, respectively.     

The kidney,adrenocortical homolog,and corpuscles of Stannius in the cockscomb pricklebackAnoplarchus purpurescens

The morphology of the kidney, adrenocortical homolog, and the corpuscles of Stannius was examined in the cockscomb prickleback,Anoplarchus purpurescens, a marine teleost which inhabits the intertidal zone. The paired kidneys of this fish are fused throughout most of their length, there is essentially a single posterior cardinal vein on the right side, they possess renal corpuscles, and there is no distal segment of the tubule. The tubule is specialized, in descending order, into ciliated neck and two proximal segments before entering the system of collecting tubules and ducts. The cells of the latter system are specialized for mucous secretion, as are cells of the main excretory ducts, the paired archinephric ducts. Tubulogenesis occurs in the kidneys in close apposition to the archinephric ducts. The presumptive adrenocortical homolog is located around the posterior cardinal veins in the head kidney while paired corpuscles of Stannius are confined to the posterior end of the kidney. All of the above features are consistent with those found in the kidneys of many other marine teleosts.     

The relationship between the ionic composition of the environment and the secretory activity of the endocrine cell types of stannius corpuscles in the teleost Gasterosteus aculeatus

Summary The corpuscles of Stannius of threespined sticklebacks contain two glandular cell types of presumed endocrine nature. To elucidate the function of both cell types the secretory activity of the cells was studied in fully adapted seawater and freshwater fishes and in specimens transferred from sea water to fresh water or adapted to media of various ionic composition. The secretory activity was established, in tissue sections and freeze-etch replicas, by estimating the volume of the nuclei, the density of the nuclear pores, and the frequency of exocytotic phenomena.The type-1 cells, ultrastructurally comparable to the predominant or only cell type described in many other teleosts, are more active in sea water than in fresh water. The activity of the type-2 cells, whose ultrastructural appearance is known only for salmonids and eels, is higher in fresh water. Transfer of seawater fishes to fresh water results in reduction of type-1 cells and activation of type-2 cells. The factors responsible for these changes were analyzed by exposure of fishes to solutions of various salts in fresh water and to artificial sea water with a reduced content of one of its components. The high activity of type-1 cells in sea water proved to be related to the high calcium content of this medium. These cells probably produce a substance comparable to hypocalcin, the endocrine factor isolated from the Stannius corpuscles of some other teleost species. The high activity of type-2 cells in fresh water appeared to be connected with the low sodium and potassium levels of this medium. Type-2 cells possibly produce a hitherto unknown hormone involved in the control of sodium and/or potassium metabolism.The technical assistance of Miss C. Mein and Mr. J. Zagers is gratefully acknowledged