Novel structures in secreting the androgenic gland hormone

The secretory granules in the androgenic gland of the terrestrial isopod Armadillidium vulgare, which have been indistinct for long time because of vulnerable structures, were revealed by using the rapid-freezing and freeze-substitution method. The fine structure of the androgenic gland is conspicuous by the distribution of numerous particular organelles in the cytoplasm consisting of the endoplasmic reticulum and the Golgi complex, and by having a number of highly organized structures developed between the androgenic gland cells. The structures connect to the intercellular space, which is seen as intercellular canaliculi for exporting the androgenic gland hormone. The plasma membranes near the particular structure of the intercellular canaliculi in the androgenic gland are often specialized to form cellular junctions. The secretory granules including the electron-dense materials, which are supposed to be peptides of androgenic gland hormone, are distributed beside the particular structure of the intercellular canaliculi. Some of the granules are seen to fuse with the plasma membranes. This observation suggests that, in the Armadillidium vulgare, the secretory granules containing androgenic gland hormone are transferred to the extracellular space through the intercellular canaliculi particularly developed for exporting the peptide hormone. This is the first evidence to show the secretory mechanism of the androgenic gland hormone in the Isopoda.     

Observations on Variations in the Male Sex Characters and Their Relation to the Androgenic Gland in the Shrimp Macrobrachium idae (Heller)

A majority of the males of the brackish water shrimp, Macrobrachium idae, show a hypertrophy in the length of the second cheliped, the length and spinuosity of the appendix masculina and the width of the vas deferens, during the breeding season. Statistical analyses of the measurements of these characters show that this hypertrophy has only very little correlation to the size of the individual, and that the above sex characters have marked variation in a population having the same body length. The hypertrophy of these structures is more linked with the extent of development of the androgenic gland. Also, in such individuals, the androgenic gland shows signs of increased secretory activity as evidenced by increase in size of the cells, vacuolisation of cytoplasm and presence of degenerative areas. It is suggested that there is a direct relation between the secretory activity of the androgenic gland and the hypertrophy of these structures i.e. there is a “cause and effect” relation between the androgenic gland and the primary and secondary sex characters.     

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.     

Chemical synthesis of insulin-like peptide 1 and its potential role in vitellogenesis of the kuruma prawn Marsupenaeus japonicus

The insulin superfamily comprises a group of peptides with diverse physiological functions and is conserved across the animal kingdom. Insulin-like peptides (ILPs) of crustaceans are classified into four major types: insulin, relaxin, gonadulin, and androgenic gland hormone (AGH)/insulin-like androgenic gland factor (IAG). Of these, the physiological functions of AGH/IAG have been clarified to be the regulation of male sex differentiation, but those of the other types have not been uncovered. In this study, we chemically synthesized Maj-ILP1, an ILP identified in the ovary of the kuruma prawn Marsupenaeus japonicus, using a combination of solid-phase peptide synthesis and regioselective disulfide bond formation reactions. As the circular dichroism spectral pattern of synthetic Maj-ILP1 is typical of other ILPs reported thus far, the synthetic peptide likely possessed the proper conformation. Functional analysis using ex vivo tissue incubation revealed that Maj-ILP1 significantly increased the expression of the yolk protein genes Maj-Vg1 and Maj-Vg2 in the hepatopancreas and Maj-Vg1 in the ovary of adolescent prawns. This is the first report on the synthesis of a crustacean ILP other than IAGs and also shows the positive relationship between the reproductive process and female-dominant ILP.     

Seasonal changes in the structure and secretory activity of the androgenic gland of Travancoriana schirnerae

This study investigated the seasonal variation in the structure and secretory activity of the androgenic gland (AG) in the freshwater crab: Travancoriana schirnerae. The androgenic gland is an elongate structure, attached to one side on the wall of the ejaculatory duct. Histological studies showed the presence of three cell types, which differ in size, shape of nuclei, and presence or absence of secretory vesicles. Type I cells are small with large nuclei whereas type II cells are large with small nuclei. Type III cells are intermediate in size and exhibited streak-like nuclei and transparent cytoplasm. Seasonal changes were discerned in the morphology, histology and secretory activity of the gland. March-June appeared to be the active season with type II cells containing secretory vesicles. The mode of release of secretion found to be holocrine. The secretory activity almost completed by July-August (the mating season) with vacuolization of type II cells. The gland remained inactive from September-December with abundance of vacuoles, scattered pycnotic nuclei, indistinct cell membranes and total cellular degeneration. January-February was the revival period with type I cell proliferation. The present study revealed that the secretory activity of the gland is in tune with the male reproductive cycle.     

Masculinization of Female Crayfish,Procambarus Clarki (Girard)

Summary

Twenty-three immature female crayfish (Procambarus clarki (Girard); carapace length = 8.2–17.9 mm), implanted with androgenic gland implants obtained from P. clarki males, were observed for 326 days for evidence of masculinization. Number of molts completed ranged from three to eight. Of eleven surviving females, three were masculinized as evidenced by the partial transformation of their first pair of pleopods into male-type gonopods. No other evidence of masculinization, either internal or external was seen. Masculinization of the first pair of pleopods was unequal and first noted 290 days post-implantation. We conclude that androgenic gland implantation can induce masculinization of P. clarki females, albeit only with great difficulty. This is the first report of masculinization of female macruran decapods by androgenic gland implantation.     

Induction par la température d'une physiologie mâle chez les néo-femelles et les intersexués du Crustacé Oniscoïde Armadillidium vulgare Latr., hébergeant un bactéroïde à action féminisante

In the Oniscoid Armadillidium vulgare, inside the thelygenic line of the Niort population, intersexed females, whatever their sizes, and most of the young neo-females from 5 to 6 mm long (males feminized by a polytropic intracytoplasmic bacteroid kept for 13— 47 days at 35°C, and then replaced at 20°C, are masculinized. The masculinization of their external sexual characters is more or less complete, and the ovary is changed into a functional testicle with one or several utricles, each of them having an androgenic neogland. This masculinization, which restores a phenotype corresponding with the genotype, goes with the disappearance of the typical forms of the bacteroid, such as they are observed in neo-females and the intersexed individuals kept at 20° C.

Yet, this male physiology is only temporary: a female physiology is restored after the animals have been kept at 20° C for 2–4 mth, but the acquired male differentiation is maintained. This implies that special forms of bacteroids continue to exist and that, when the host is again kept at 20° C, they produce the typical feminizing factors.

The absence of masculinization in neo-female adults is not due to the maintenance of the bacteroid, but to the impossibility of inducing the differentiation of an androgenic neo-gland after the 6th molt of the postembryonic development; the cells of the primal androgenic gland—which exist in all females—have then completely disappeared, or have definitively turned into conjunctival cells. Masculinization does not occur either in real young females (genetic females), which proves that temperature is only an indirect cause, and acts by inhibition of the feminization action of the bacteroid.     

Cells producing insulin-like androgenic gland hormone of the giant freshwater prawn, Macrobrachium rosenbergii, proliferate following bilateral eyestalk-ablation

We found that the androgenic gland (AG) of Macrobrachium rosenbergii possesses three cell types. Type I cells are small polygonal shaped-cells (13.4 μm in diameter), stain strongly with hematoxylin-eosin (H&;E), have abundant multilayered rough endoplasmic reticulum (rER), and nuclei containing mostly heterochromatin. Type II cells are slightly larger (18.6 μm in diameter), stain lightly with H&;E, have rER with dilated cisternae, and nuclei containing mostly euchromatin. Type III cells (previously undescribed) are similar in size and shape to type I cells, but the cytoplasm is unstained and they have a high amount of smooth endoplasmic reticulum (sER) and mitochondria with tubular cristae. Bilateral eyestalk-ablation resulted in AG hypertrophy with a proliferation and predominance of type I cells as determined by bromodeoxyuridine (BrdU) assays. Expression of insulin-like androgenic gland hormone (Mr-IAG), determined by immunohistochemistry, was weak in type I cells, strong in type II cells of both the intact and eyestalk-ablated, and negative in type III cells. It was also detected in spermatogonia, nurse cells, and epithelium lining of the spermatic duct. The function of Mr-IAG in these tissues is yet to be elucidated but the distribution implies a strong role in male reproduction.     

Bilateral eyestalk ablation of the blue swimmer crab, Portunus pelagicus, produces hypertrophy of the androgenic gland and an increase of cells producing insulin-like androgenic gland hormone

The androgenic glands (AG) of male decapod crustaceans produce insulin-like androgenic gland (IAG) hormone that controls male sex differentiation, growth and behavior. Functions of the AG are inhibited by gonad-inhibiting hormone originating from X-organ-sinus gland complex in the eyestalk. The AG, and its interaction with the eyestalk, had not been studied in the blue swimmer crab, Portunus pelagicus, so we investigated the AG structure, and then changes of the AG and IAG-producing cells following eyestalk ablation. The AG of P. pelagicus is a small endrocrine organ ensheathed in a connective tissue and attached to the distal part of spermatic duct and ejaculatory bulb. The gland is composed of several lobules, each containing two major cell types. Type I cells are located near the periphery of each lobule, and distinguished as small globular cells of 5-7 μm in diameter, with nuclei containing mostly heterochromatin. Type II cells are 13-15 μm in diameter, with nuclei containing mostly euchromatin and prominent nucleoli. Both cell types were immunoreactive with anti-IAG. Following bilateral eyestalk ablation, the AG underwent hypertrophy, and at day 8 had increased approximately 3-fold in size. The percentage of type I cells had increased more than twice compared with controls, while type II cells showed a corresponding decrease.     

The Crustacean Androgen: A Hormone in an Isopod and Androgenic Activity in Decapods

The androgenic gland has been described in a variety of crustaceanspecies—isopods, amphipods and decapods. It has been shownto play a role in the regulation of male differentiation andin the inhibition of female differentiation. Upon its applicationfor endocrine manipulation, it inhibits female characteristics.Recently, the androgenic hormone from the isopod Armadillidiumvulgare was purified and characterized on the basis of a morphologicalbioassay. The hormone is a glycosylated protein composed oftwo peptide chains connected each to the other by two disulfidebridges. The pro-hormone consists of the same two chains connectedby a third peptide in a complex that resembles the insulin superfamily hormones. The study of the androgenic gland in decapodslags behind that in the isopods, and a decapod androgenic hormonehas yet to be identified. In this review, five decapod speciesare described as models, in which the androgenic gland exertsmorphological, anatomical, physiological and behavioral effects.These models could serve as the basis of possible bioassaysfor the study of the structure and mode of action of the androgenichormone in decapod crustaceans.     

Structure of the apical cells of the testis of the tenebrionid beetles: Tenebrio molitor and Zophobas rugipes

The developmental cytology of the apical tissue of the testis of Tenebrio molitor and Zophobas rugipes was studied with light and electron microscopy. In the early larvae of both species the tisue was found to be a thickened protrusion of nongerminal cells appearing at the apical end of each testis follicle following gonadal differentiation. The cells persist through pupal and adult stages in both species, becoming more prominent at these stages in Z. rugipes, despite tracheal invasion in both species. In older adults the apical tissue regresses and ultimately distintegrates. Ultrastructurally the apical cells are distinguished from adjacent germinal cells by their (1) small, rounded or oval nuclei, (2) highly convoluted plasma membrane, (3) electron-opaque cytoplasm, (4) profuse concentrically-stacked, granular endoplasmic reticulum, (5) large aggregates of glycogen-like granules, (6) numerous small, tubular mitochondria, (7) well-developed Golgi centers and (8) striking arrays of microtubules. These cells have many cytological features in common with the androgenic gland cells of crustaceans, but not with the steroidogenic cells of vertebrates. Evidence for the formation of protein granules is also lacking. As yet, experimental procedures have not indicated an endocrine function for these cells in tenebrionids. However, their cytology is consistent with secretory activity of some kind.     

Inhibitory effects of the androgenic gland on ovarian development in the mud crab Scylla paramamosain

Isolation and characterization of androgenic hormone in decapod crustaceans depend on an effective bioassay of its action. In the present study, the effect of androgenic gland on ovarian development in the mud crab Scylla paramamosain was investigated with a view to develop a bioassay for androgenic hormone. Ovarian regression with degeneration of oocytes occurred in some female crabs implanted with androgenic gland in vivo. In vitro incubation of ovarian tissues at secondary vitellogenesis in extract of androgenic gland resulted in a significant decrease in amino acid uptake by the tissues. We propose that this inhibitory effect could be established as an effective bioassay for the isolation of androgenic hormone in the mud crab.     

The structure of a glycosylated protein hormone responsible for sex determination in the isopod, Armadillidium vulgare.

Two glycoforms (AH1 and AH2) of androgenic hormone, and its corresponding hormone precursor derived from HPLC-purified androgenic gland extract from the woodlouse Armadillidium vulgare were fully characterized by microsequencing and mass spectrometry. The amino-acid sequences of the two glycoforms were identical; they consist of two peptide chains, A and B, of 29 and 44 amino acids, respectively, with chain A carrying one N-glycosylated moiety on Asn18. The two chains are linked by two disulfide bridges. Glycoforms were only differentiated by the size and heterogeneity of the glycan chain. The androgenic hormone precursor (16.5 kDa) was shown to contain the sequence of chains A and B from the androgenic hormone, connected by a C-peptide (50 amino acids). These results were confirmed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analysis performed on a single hypertrophied androgenic gland. When injected into young females, both glycoforms of the androgenic hormone were able to override genetic sex-determination. In invertebrates, there is no other example where sex-differentiation is controlled by a protein hormone that is not synthesized by the gonads but by a special gland. A functional comparison with two other hormones which are believed to play a role in sex determination, i.e. ecdysone in insects and anti-Müllerian hormone in mammals, is presented. Work is in progress to clone and characterize the gene encoding androgenic hormone, moreover special attention is devoted to its regulatory regions, putative targets for the Wolbachia action.     

Mechanisms of parasite-induced sex reversal in Gammarus duebeni

The amphipod Gammarus duebeni is host to the feminising microsporidian parasite Nosema granulosis that converts males into functional females. To test the hypothesis that the parasite acts through endocrine disruption we compared the morphology of the gonad and activity of the androgenic gland, which coordinates male sexual differentiation, in infected and uninfected animals. Male gonad consisted of testis, seminal vesicle and vas deferens that was anchored to the genital papilla on segment 7. The androgenic gland was associated with the distal end of the vas deferens. In female and intersex animals the bi-lobed ovary opened into the oviduct at segment 5, vestigial vas deferens and vestigial androgenic gland were retained. The majority of parasitised individuals (38/39) were either phenotypic females or intersexes with fully developed ovaries and an undifferentiated androgenic gland. Our data suggest that the parasite prevents differentiation of the androgenic gland. In further support of this hypothesis, mass spectrometry of a single androgenic gland from males revealed a dominant molecular ion with a mass/charge ratio of 4818.4+H, corresponding to a peptide of androgenic gland hormone from Armadillidium vulgare. In contrast the vestigial androgenic gland from parasitised and unparasitised females showed only low intensity peaks. Our observations demonstrate that the parasite manipulates host sex by preventing androgenic gland differentiation, androgenic gland hormone production and consequently male differentiation. This is in agreement with observations of A. vulgare with inherited Wolbachia infection, suggesting that phylogenetically distant feminisers manipulate hosts through a common mechanism. The high frequency of infection in intersexes (89.3%) suggests that this phenotype results from incomplete feminisation by the parasite.     

Androgen receptor expression in the rat prostate is down-regulated by dietary phytoestrogens

Background  

It is well established that the growth of the prostate gland is a hormone-dependent phenomenon involving both androgenic and estrogenic control. Proliferation of prostate cells is, at least in part, under control of estrogen receptor beta (ER-beta). Phytoestrogens bind ER-beta with high affinity and therefore may have antiproliferative effects in the prostate.     

The Ultrastructure of the Gastrodermal Gland Cells in the Freshwater Planarian Dugesia gonocephala s.l.

Light and transmission electron microscopy have been used to study the gastrodermal gland cells of the triclad Dugesia gonocephala s.l. The events involved in the ultrastructural transformation and the secretion process in these cells were followed at four different stages in both fasted and fed animals. During the feeding stage their secretory granules are directly discharged into the intestinal lumen by means of a secretion process of the holocrine type that is described in this paper. It is suggested that such secretions contribute to extracellular digestion and that disintegration of the gland cells is accompanied by a differentiation of neoblasts into new gland cells, reflecting a turnover of gland cells during the triclad digestive stages.     

Histochemistry of the glands associated with the reproductive tract ofLymnaea stagnalis

Summary The albumen gland, the muciparous gland and the oöthecal gland of female genital tract of Lymnaea stagnalis, collected in spring, autumn and winter have been studied.The reactions for polysaccharides, proteins and RNA have been performed in order to characterise the secretion of the glands.The albumen gland secretion consists almost exclusively of slightly acid polysaccharides whose histochemical reactions, according to Lison and Grainger and Shillitoe confirm the presence of galactogen. Proteins are also present in the secretion. The muciparous gland secretion consists of strongly acid mucopolysaccharides (non sulphated) produced by large cells among which small cells containing sulphated mucopolysaccharides are present.In the oöthecal gland two zones are present, one with a single type of cells containing acid mucopolysaccharides, and the other with two different types of cells: the first with mucopolysaccharides and the second with sulphated mucopolysaccharides, proteins and glycogen at the basis of the cell. Sialic acids are not present in the secretion of the glands studied.The polysaccharidic composition of the secretion of the glands is different from gland to gland. The secretion of the glands gradually changes and gets acid according to the composition of the various membranes and envelopes wrapping up the eggs.     

Endocrine and genetic control of sex differentiation in the Malacostracan Crustacea

Summary

Sex differentiation in Malacostraca is controlled by hormone secreted from the androgenic glands. Experimentally induced sex inversions in isopods and amphipods proved that the genetic female and male possess primordia of the androgenic glands, gonads, and gonoducts, along with sexual characteristics of both sexes. During the sensitive period, the presence or absence of androgenic gland hormone (AGH) affects the differentiation of these primordia.

Genetic control of the development of androgenic gland primordium seems to be brought about assuming of the following: 1. Both genetic female and male possess gene(s) (AGH-G) responsible for the AGH-synthesis situated on the homologous loci of the sex chromosomes and/or on the autosomes. 2. The gene(s) are activated spontaneously with the lack of inhibition of the major sex factor carried by the W or X chromosome. The W and X factors are hypostatic to major sex factor carried by the Y chromosome. The Z factor does not seem to influence sex differentiation. Sufficient allochthonous AGH seems to render the W and X factors ineffective.     

The structure of the salt gland of Aegiceras corniculatum

Summary The salt glands of Aegiceras corniculatum have been examined by light- and electron-microscope techniques. A gland consists of a large number of abutting secretory cells and a single, large basal cell. The secretory cells and basal cell are joined by well defined plasmodesmata. The glandular cuticle shows differences between the top and sides of the gland, which may indicate a variation in the nature or quality of wax deposited. These variations may be significant in the secretion process, in view of the lack of evidence for the presence of pores. In ultrastructure, the secretory cells are generally similar to others that have been described, though there is no evidence of any particular association of vacuoles within these cells.