The ultrastructural basis of steroid production in the Y-organ and the mandibular organ of the crabs Hemigrapsus nudus (Dana) and Carcinus maenas L.

Summary The ultrastructure of the steroid producing Y-organ and the mandibular organ of the crustaceans Hemigrapsus nudus and Carcinus maenas has been studied with reference to the well investigated steroid secreting cells (SSC) of mammals. In accordance with the most important characteristic of mammalian SSC, abundant SER could be shown in the Y-organ, where it is unevenly distributed. The amount of SER seems to vary in correlation with the secretion of moulting hormone during the moult cycle. Most Y-organ cells contain a great number of mitochondria of the tubular type, another important characteristic of mammalian SSC. The ultrastructure of the mandibular organ of C. maenas differs considerably from that of the Y-organ. Some SER was found, mitochondria of unusual shape and size were conspicuous. No definite conclusion as to the function of the mandibular organ is yet to be drawn.Dedicated to Prof. Dr. Peter Karlson on the occasion of his 60th birthdaySupported by the Deutsche Forschungsgemeinschaft, grant Ad 24/4We wish to thank Dr. A. Owczarzak, Oregon State University, Corvallis, Oregon, for providing the facilities for our work with H. nudus and Thomas Gallenstein for many helpful discussions of technical problems     

Extracellular esterase activity as an indicator of endoplasmic reticulum calcium depletion

Abstract

Context: Endoplasmic reticulum (ER) calcium depletion is associated with diverse diseases, including cardiac, hepatic, and neurologic diseases.

Objective: The aim of the present study was to identify and characterize an endogenous protein that could be used to monitor ER calcium depletion comparably to a previously described exogenous reporter protein.

Materials and methods: The use of a selective esterase-fluorescein diester pair allowed for carboxylesterase activity in extracellular fluid to be measured using a fluorescent readout. Cell culture media from three different cell lines, rat plasma, and human serum all possess quantifiable amounts of esterase activity.

Results: Fluorescence produced by the interaction of carboxylesterases with a fluorescein diester substrate tracks with pharmacological and physiological inducers of ER calcium depletion. The fluorescence measured for in vitro and in vivo samples were consistent with ER calcium depletion being the trigger for increased esterase activity.

Discussion: Decreased luminal ER calcium causes ER resident esterases to be released from the cell, and, when assessed concurrently with other disease biomarkers, these esterases may provide insight into the role of ER calcium homeostasis in human diseases.

Conclusion: Our results indicate that carboxylesterases are putative markers of ER calcium dysfunction.     

Bioactive forms of gonadotropin releasing hormone in the brain of an Indian major carp,Catla catla (Ham.)

Two forms of biologically active gonadotropin releasing hormones were isolated from the hypothalami ofCatla catla. Gonadotropin releasing hormone activity was studiedin vitro using enzymatically dispersed carp pituitary cell incubation system. Gonadotropin released into the medium was measured by carp gonadotropin-radio immuno assay. Acetic acid extracted hypothalamic material was subjected to acetone fractionation. Among the three protein pellets obtained at different time periods (ACI, ACII and ACIII), AC II exhibited the gonadotropin releasing hormone activity. Gel filtration of AC II through Sephadex G-25 column showed three protein peaks (SG I, SG II SGIII) and only S G II demonstrated strong gonadotropin releasing hormone activity. Elution of SG II through FPLC Mono Q column (an anion exchanger) in NaCl gradient programme showed one unadsorbed (MQ I) and three adsorbed (MQ II, MQ III and MQ IV) protein peaks. MQ III, which was eluted with 51% NaCl, exhibited gonadotropin releasing hormone activity. Surprisingly, unadsorbed fractions, MQ I, also showed gonadotropin releasing hormone activity. MQ 1 was therefore subjected to FPLC Mono S (a cation exchanger) column chromatography where a highly active gonadotropin releasing hormone enriched peak, i.e., MS III, could be eluted with 45% NaCl. These findings show thatCatla catla hypothalamus has two forms of gonadotropin releasing hormones one anionic (carp gonadotropin releasing hormone I) and another cationic (carp gonadotropin releasing hormone II). These two forms of gonadotropin releasing hormones were also active in heterologous carp species, rohu(Labeo rohita), mrigal(Cirrhinus mrigala) and an exotic common carp(Cyprinus carpio). Combined activity of two forms of gonadotropin releasing hormones was significantly greater as compared to any of the single form.     

Individual and combined effects of calciotropic hormones and growth factors on mineral metabolism in embryonic chick tibiae

Summary We have investigated single and combined effects of calciotropic hormones and growth factors on the regulation of alkaline phosphatase (ALP) activity and calcium metabolism in an optimized serum-free bone organ culture system of embryonic chick tibiae. Parathyroid hormone PTH(1–34) alone mobilized calcium from bone tissue time- and dose-dependently and inhibited ALP activity. Both the bisphosphonate (BM 21.0955) and to a lesser extent salmon calcitonin alone slightly increased calcium uptake and inhibited the stimulation of bone resorption by PTH(1–34). 1,25(OH)₂D₃ mobilized calcium and inhibited ALP activity in contrast to 24,25(OH)₂D₃ which inhibited ALP activity but had no significant effect on calcium metabolism. Interestingly the combination of PTH(1–34) with 1,25(OH)₂D₃ but not 24,25(OH)₂D₃ reduced calcium mobilization. The combination of the midregional fragment PTH(28–48), which by itself has no effect on calcium metabolism, with 1,25(OH)₂D₃ reduced calcium mobilization more efficiently. Several PTH-regulated mediators have been assayed in this system. Of the tested growth factors, IGF-I at high concentrations caused bone resorption with no effect on ALP activity. TGF-β₁ (transforming growth factor β) and BMP-2 had no significant effect on calcium metabolism; however, ALP activity was inhibited by TGF-β₁ and induced dose dependently by BMP-2. Of the other factors known to be present in bone, platelet-derived growth factor (PDGF_A/B) and epidermal growth factor (EGF) had a small effect on calcium mobilization but had no effect on ALP activity. bFGF reduced ALP activity slightly without an effect on calcium metabolism. Our results show that this in vitro system can mimic some interactions of calciotropic hormones in vivo and allows the assaying of mediators in terms of regulation of ALP activity and of calcium metabolism.     

cDNA cloning of a mandibular organ inhibiting hormone from the spider crabLibinia emarginata

Mandibular organs (MO) produce a crustacean juvenile hormone, methyl farnesoate (MF). MO activity is negatively regulated by factors, called mandibular organ inhibiting hormones (MOIHs), from the crustacean sinus gland X-organ complex in the eyestalks. Three MOIHs have been isolated previously from the spider crabLibinia emarginata and are characterized as members of the crustacean hyperglycemic hormone (CHH) neuropeptide family. In the research reported here, a full length cDNA sequence of 972 bp of a MOIH was isolated by screening a cDNA library constructed from the eyestalks ofLibinia emarginata. This cDNA sequence encodes a preprohormone peptide with 137 amino acid residues, including a 26-amino acid long signal peptide, a 34-amino acid long precursor peptide, a dibasic peptide, the full length of 72-amino acid long MOIH, and a tri-peptide Gly-Lys-Lys which designates the potential amidation site at the C-terminus of the mature peptide.     

The mysid Siriella armata,a biological model for the study of hormonal control of molt and reproduction in crustaceans: a review

Summary

The mysid Siriella armata provides a new biological model for investigations on the molting and reproductive physiology in crustaceans. The main endocrine centres (Y-organ, mandibular organ, androgenic gland, X-organ and sinus gland) have been described and are available for experimentation. Experimental cautery of Medulla Interna-Medulla Externa-X-organ-sinus gland complex (MI-ME-X-organ-SG) of the eyestalk inhibited molt and brood production demonstrating that the complex plays a role in regulation, at least via a positive action upon the circulating ecdysteroids. In the present paper, the results already obtained are reviewed and the perspectives offered by this biological model discussed in reference to other crustaceans.     

Role of calcium in plant hormone action

Abstract

The role of calcium as a second messenger in plant cells has been recognized in a number of physiological processes. As described for animal systems, plant cells contain all the elements necessary for coupling the external signals to a specific response by regulation of calcium levels. However, the evidence that Ca₂₊ can be considered a second messenger for hormone response in plants is still circumstantial, besides several reports on the subject have been produced. All the hormone effects may in some tissues be regulated by calcium metabolism, but only for few of them a precise role of this cation has been established. The studies on the different hormones will be reviewed and discussed.     

The calcium-mediated promotion of mitotic activity in rat thymocyte populations by growth hormone, neurohormones, parathyroid hormone and prolactin

Growth hormone, oxytocin, parathyroid hormone, prolactin and lysine vasopressin strongly stimulate mitotic activity in rat thymocyte populations maintained in vitro. These hormones have no mitotic effect on cells maintained in calcium-free medium. It is concluded that they stimulate mitosis only indirectly by sensitising the mitotically competent segment of a thymocyte population to the action of calcium. The stimulatory action of calcium itself is opposed by low concentrations of the mucopolysaccharide chondroitin sulphate. However, the inhibitory action of chondroitin sulphate can be overcome by growth hormone. A possible common mechanism of action of these hormones on mitotically competent cells is discussed.     

An unusual edentulous pterosaur from the Early Cretaceous Romualdo Formation of Brazil

Numerous taxa make up the Early Cretaceous fauna of Brazil, including Ornithocheiroidea, Tapejaridae, Thalassodromidae, Chaoyangopteridae and a purported member of Azhdarchidae. Dsungaripteridae has only been tentatively assumed to be present in the form of ‘Santanadactylus’ spixi. New study of NMSG SAO 251093 (a specimen referred to Thalassodromeus sethi) suggests it is a previously unknown species of dsungaripterid, Banguela oberlii, tax. nov., differing from Thalassodromeus and other pterosaurs from the Early Cretaceous of Brazil by a unique combination of characters, including an upturned jaw tip, a short dorsal mandibular symphyseal shelf (dmss), and an autapomorphic thin crest placed halfway along the fused mandibular symphysis without a keel along the ventral margin of the jaw. B. oberlii, tax. nov., is referred to Dsungaripteridae based on a dmss no longer than the ventral shelf, U-shaped caudal margin of the ventral shelf and lateral margins of the mandibular symphysis concave in dorsal view. B. oberlii, tax. nov., is the youngest known dsungaripterid, and expands known morphological diversity in the clade as well as the Early Cretaceous pterosaur fauna of South America.     

The control of teleost ACTH cells

Summary Adrenocorticotropic hormone was spontaneously released from goldfish pituitaries in vitro, most of the activity (79%) coming from the anterior half of the gland. It is distinct from melanophore stimulating hormone, 86% of which was released from the posterior half of the gland.Cortisol treatment of whole animals increased the adrenocorticotropic hormone content of the pituitaries put had no effect on the thyrotropic hormone content. In organ cultured pituitaries cortisol (5 /ml) inhibited the release of adrenocorticotropic hormone from the glands by 65% while hypothalamic homogenates increased the release by 32%. The spontaneous activity of adrenocorticotropic hormone cells may be controlled by inhibition by cortisol and stimulation by the hypothalamus possibly acting via a releasing factor.The technical assistance of Miss P. Robins is gratefully acknowledged.     

A Novel Approach to Enhance the Urease Activity of Sporosarcina pasteurii and its Application on Microbial-Induced Calcium Carbonate Precipitation for Sand

Abstract

Urease is involved in the formation of carbonate sediments by microbial-induced calcium carbonate precipitation (MICP), and Sporosarcina pasteurii used extensively in this technique owing to its high urease production. In this study, a simple two-step culture method with the appropriate medium was developed to enhance the urease activity of S. pasteurii. Urea played an important role in the culture process, particularly during the pre-cultivation step and the newly developed method improved both urease activity and specific urease activity. Furthermore, the increase in urease activity by MICP resulted in increased production of calcium carbonate and better strength of bio-cemented sand.     

Separation of AG function in floral meristem determinacy from that in reproductive organ identity by expressing antisense AG RNA

The Arabidopsis floral homeotic gene AGAMOUS (AG) is a regulator of early flower development. The ag mutant phenotypes suggest that AG has two functions in flower development: (1) specifying the identity of stamens and carpels, and (2) controlling floral meristem determinacy. To dissect these two AG functions, we have generated transgenic Arabidopsis plants carrying an antisense AG construct. We found that all of the transgenic plants produced abnormal flowers, which can be classified into three types. Type I transgenic flowers are phenocopies of the ag-1 mutant flowers, with both floral meristem indeterminacy and floral organ conversion; type II flowers are indeterminate and have partial conversion of the reproductive organs; and type III flowers have normal stamens and carpels, but still have an indeterminate floral meristem inside the fourth whorl of fused carpels. The existence of type III flowers indicates that AG function can be perturbed to affect only floral meristem determinacy, but not floral organ identity. Furthermore, the fact that floral meristem determinacy is affected in all transformants, but floral organ identity only in a subset of them, suggests that the former may required a higher level of AG activity than the latter. This hypothesis is supported by the levels of AG'mRNA detected in different transformants with different frequencies of distinct types of abnormal antisense AG transgenic flowers. Finally, since AG inhibits the expression of another floral regulatory gene AP1, we examined AP1 expression in antisense AG flowers, and found that AP1 is expressed at a relatively high level in the center of type II flowers, but very little or below detectable levels in the inner whorls of type III flowers. These results provide further insights into the interaction of AG and AP1 and how such an interaction may control both organ identity and floral meristem determinacy.     

Recombinant Human Parathyroid Hormone Therapy (1-34) In an Adult Patient with a Gain-of-Function Mutation in the Calcium-Sensing Receptor-a Case Report

ObjectiveTo describe a case of hypocalcemia in a patient with a gain-of-function mutation in the calcium-sensing receptor that was undetected until adulthood and successfully treated with recombinant parathyroid hormone.MethodsThe clinical findings, laboratory data, and a review of the pertinent literature are presented.ResultsA 55-year-old woman was hospitalized and seen by the endocrinology consult service for hypocalcemia that was refractory to repeated doses of intravenous calcium gluconate. She expressed concern about chronic leg muscle cramps and paresthesias of the lips and fingertips. In addition, she had no history of neck surgery, neck irradiation, or any autoimmune disease. She was a well-appearing female with no dysmorphic features or skin changes. Laboratory tests revealed hypocalcemia, hyperphosphatemia, hypomagnesemia, and hypovitamino-sis D. Her parathyroid hormone concentration (PTH) was low at 14.2 pg/mL. Her PTH and calcium concentrations remained low despite repletion of magnesium and treatment with calcitriol and oral calcium replacement. A 24-hour collection for urinary calcium showed inappropriate hypercalciuria. Medical records showed her hypocalcemia to be chronic. Additionally, several family members had also complained of muscle cramps. A congenital cause of her hypoparathyroidism was considered, and genetic testing confirmed heterozygosity for a gain-of-function mutation in the calcium-sensing receptor gene associated with autosomal dominant familial isolated hypoparathyroidism (ADH). Treatment with subcutaneous recombinant human parathyroid hormone teriparatide (rhPTH [1-34]) 20 mcg twice daily for three days normalized her calcium and phosphorus concentrations.ConclusionrhPTH (1-34) is an effective treatment for patients with hypoparathyroidism due to gain-of-function mutations in the calcium-sensing receptor. ADH can be insidious in presentation and the diagnosis can be missed unless there is a high index of suspicion. (Endocr Pract. 2013;19:e24-e28)     

Fibroblast growth factor 10 regulates Meckel's cartilage formation during early mandibular morphogenesis in rats

Fibroblast growth factors (FGF) are pluripotent growth factors that play pivotal roles in the development of various organs. During mandibular organogenesis, Meckel's cartilage, teeth, and mandibular bone differentiate under the control of various FGF. In the present study, we evaluated the role of FGF10 in rat mandibular chondrogenesis and morphogenesis using mandibular organ culture and mandibular cell micromass culture systems. The overexpression of Fgf10 induced by the electroporation of an FGF10 expression vector not only altered the size and shape of Meckel's cartilage, but also upregulated the expression of the cartilage characteristic genes Col2a1 and Sox9 in a mandibular organ culture system. Meckel's cartilage was deformed, and its size was increased when Fgf10 was overexpressed in the lateral area of the mandible. Meanwhile, no effect was found when Fgf10 was overexpressed in the medial portion. In the mandibular cell micromass culture, recombinant FGF10 treatment enhanced chondrogenic differentiation and endogenous ERK (extracellular signal-regulated kinase) phosphorylation in cells derived from the lateral area of the mandible. On the other hand, FGF10 did not have significant effects on mandibular cell proliferation. These results indicate that FGF10 regulates Meckel's cartilage formation during early mandibular morphogenesis by controlling the cell differentiation in the lateral area of the mandibular process in rats.     

Primer effect of queen pheromone on juvenile hormone biosynthesis in adult worker honey bees

Juvenile hormone synthesis in adult worker honey bees was measured by an in vitro corpora allata bioassay. Adult queenless workers exhibit higher rates of juvenile hormone biosynthesis than queenright workers. Hormone synthesis is not correlated with the volume of the glands. Extract of queen mandibular glands, applied to a dummy, reduces juvenile hormone biosynthesis in caged queenless workers to the level of queenright workers. The same result was obtained with synthetic (E)-9-oxo-2-decenoic acid, the principal component of the queen mandibular gland secretion. This pheromonal primer effect may function as a key regulating element in maintaining eusocial colony homeostasis. The presence of brood does not affect the hormone production of the corpora allata.Abbreviations BSA bovine serum albumin - CA Corpora allata - JH juvenile hormone - 9-ODA (E)-9-oxo-2-decnoic acid     

Inhibition of the development of the reproductive tract in parasitized snails

Summary

Myoblasts, muscle cells with the capacity to divide, have been detected in “Anlagen” of the male copulation organ of Lymnaea stagnalis. They only occur in the apical part of the penis. Here they could be found throughout life. Mitotic activity of these cells can be demonstrated by using an antiserum to a S-phase specific cell cycle marker, PCNA [see, e.g., Baserga (1991)]. The number/percentage of PCNA positive myoblasts is a good parameter for growth of this male copulation organ and hence also for inhibition of its growth and development as occurs in parasitized snails. In transplantation experiments, “Anlagen” of the copulation organ were used from snails 7–9 weeks after being parasitized as they can be excised in this stage and transplanted into either parasitized or nonparasitized snails. These experiments have indicated that humoral, parasitic excretory/secretory factors can be responsible for the inhibition of growth and differentiation of the copulation organ in parasitized snails as reflected by a relatively low number of PCNA positive myoblasts compared to the controls. Data obtained in in vitro experiments showed a significant decrease of the number of myoblasts in “Anlagen” cultured in the presence of parasitic E/S products. The fact that no significant effect was found on the relative low number of PCNA positive myoblasts is discussed. The effect of parasitic E/S products on these myoblasts appeared to be exerted in a direct way, not mediated by CNS-derived factors or by factors from cells in the connective tissue sheath around the CNS. Although it appears possible to use transplantation and/or in vitro culturing of these “Anlagen” as a bioassay for identification of the parasitic factor(s) responsible for the inhibitory effects on myoblasts, the methods are very laborious and do not seem very appropriate for testing many fractions of E/S products.     

The roles of PPARs in human diseases

Abstract

Peroxisome proliferator-activated receptors (PPARs), as members of nuclear hormone receptor superfamily, can be activated by binding natural or synthetic ligands. The use of related ligands has revealed many potential roles for PPARs in the pathogenesis of some human metabolic disorders and inflammatory-related disease. Based on the previous studies, this review primarily concluded the current progress of knowledge regarding the specific biological activity of PPARs in cancers, atherosclerosis, and type 2 diabetes mellitus, providing a foundation for the potential therapeutic use of PPAR ligands in human diseases.     

The occurrence of an adult reproductive diapause in the univoltine life cycle of the beech leaf mining weevil,Rhynchaenus fagi L.

Summary

Juvenile hormone (JH) and α-naphthyl acetate (α-NA) esterase activity was measured on a daily basis during embryogenesis of the house cricket, Acheta domesticus. In eggs dissected from the lateral oviducts and embryos through blastokinesis, there were elevated levels of nonspecific JH esterase activity. The JH esterase activity could not be resolved from the α-NA esterase activity by gel filtration chromatography and the metabolism of both substrates was inhibited equally by 0,0-diisopropyl phosphorofluoridate (DFP). From blastokinesis through egg hatch, the JH esterase activity was maintained at relatively low levels and was resolved from the α-NA esterase activity by gel filtration. The α-NA esterase activity was inhibited by DFP while the JH esterase activity was relatively unaffected. Low JH titers in eggs must be maintained through blastokinesis for normal development. Elevated JH esterase activity in eggs during this period appears to have a functional role in the metabolism of maternal JH in the egg.     

Low dose of dopamine may stimulate prolactin secretion by increasing fast potassium currents

Dopamine (DA) released from the hypothalamus tonically inhibits pituitary lactotrophs. DA (at micromolar concentration) opens potassium channels, hyperpolarizing the lactotrophs and thus preventing the calcium influx that triggers prolactin hormone release. Surprisingly, at concentrations ∼1000 lower, DA can stimulate prolactin secretion. Here, we investigated whether an increase in a K⁺ current could mediate this stimulatory effect. We considered the fast K⁺ currents flowing through large-conductance BK channels and through A-type channels. We developed a minimal lactotroph model to investigate the effects of these two currents. Both I _BK and I _A could transform the electrical pattern of activity from spiking to bursting, but through distinct mechanisms. I _BK always increased the intracellular Ca²⁺ concentration, while I _A could either increase or decrease it. Thus, the stimulatory effects of DA could be mediated by a fast K⁺ conductance which converts tonically spiking cells to bursters. In addition, the study illustrates that a heterogeneous distribution of fast K⁺ conductances could cause heterogeneous lactotroph firing patterns. Action Editor: Christiane Linster     

Regulation of the Crustacean Mandibular Organ

The crustacean mandibular organ (MO) produces methyl farnesoate(MF), a juvenile hormone-related compound thought to have rolesin crustacean reproduction and development. Therefore, the controlof MF production by the MO has been of considerable interest.Current evidence indicates that the MO is negatively regulatedby peptides present in the eyestalk (MO inhibiting factor, MO-IH).Several eyestalk neuropeptides have been identified that inhibitMF synthesis by MO incubated in vitro. The amino acid sequencesof these MO-IH peptides are similar to peptides in the crustaceanhyperglycemic hormone (CHH) family of neuropeptides. In addition,there appears to be a compound in the eyestalk that lowers hemolymphlevels of MF in vivo but does not directly affect the MO invitro. The inhibition of MF synthesis by eyestalk peptides involvesthe inhibition of farnesoic acid O-methyl transferase, the lastenzyme in the MF biosynthetic pathway. The activity of thisenzyme is affected by cyclic nucleotides, suggesting that thesecompounds may be involved in the signal transduction pathwaymediating the effects of MO-IH.