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Persia Jothy T, Rajesh Kannan R, Subramoniam T. Lipid and carotenoid metabolism in the developing embryos of the intertidal anomuran crab, Emerita asiatica (Milne Edwards). INVERTEBR REPROD DEV 2019. [DOI: 10.1080/07924259.2019.1608325] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- T Persia Jothy
- Molecular and Nanomedicine Research Unit, Centre for Nanoscience and Nanotechnology, Sathyabama Institute of Science and Technology, Chennai, Tamil Nadu, India
| | - R Rajesh Kannan
- Molecular and Nanomedicine Research Unit, Centre for Nanoscience and Nanotechnology, Sathyabama Institute of Science and Technology, Chennai, Tamil Nadu, India
| | - T Subramoniam
- Center for Climate Change Studies, Sathyabama Institute of Science and Technology, Chennai, Tamilnadu, India
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Techa S, Alvarez JV, Sook Chung J. Changes in ecdysteroid levels and expression patterns of ecdysteroid-responsive factors and neuropeptide hormones during the embryogenesis of the blue crab, Callinectes sapidus. Gen Comp Endocrinol 2015; 214:157-66. [PMID: 25101839 DOI: 10.1016/j.ygcen.2014.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 07/06/2014] [Accepted: 07/21/2014] [Indexed: 11/20/2022]
Abstract
Embryogenesis requires the involvement and coordination of multiple networks of various genes, according to a timeline governing development. Crustacean embryogenesis usually includes the first molt, a process that is known to be positively controlled by ecdysteroids. We determined the amounts of ecdysteroids, as well as other related factors: the ecdysone receptor (CasEcR), the retinoid X receptor (CasRXR), the molt-inhibiting hormone (CasMIH), and crustacean hyperglycemic hormone (CasCHH) during the ovarian and embryonic developments of Callinectes sapidus. In summary, the ovaries at stages 1-4 have expression levels of maternal CasEcR and CasRXR 10-50 times higher than levels seen in embryos at the yolk stage. This large difference in the amount of the these factors in C. sapidus ovaries suggests that these maternal ecdysteroid-responsive factors may be utilized at the initiation of embryogenesis. During embryogenesis, the changes in total ecdysteroids and levels of CasEcR and CasRXR expression are similar to those observed in juvenile molts. The full-length cDNA sequence of the C. sapidus BTB domain protein (CasBTBDP) initially isolated from Y-organ cDNA, contains only Broad-Complex, Tramtrack, and Bric a brac (BTB) domains. The levels of CasBTBDP are kept constant throughout embryogenesis. The expression profiles of CasMIH and CasCHH are similar to the titers of ecdysteroids. However, the timing of their appearance is followed by increases in CasEcRs and CasRXRs, implying that the expressions of these neuropeptides may be influenced by ecdysteroids. Moreover, the ecdysteroid profile during embryogenesis may track directly with the timing of organogenesis of Y-organs and their activity. Our work reports, for first time, the observed expression and changes of ecdysteroid-responsive factors, along with CasCHH and CasMIH, during embryogenesis in the crustacean C. sapidus.
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Affiliation(s)
- Sirinart Techa
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 E. Pratt Street, Columbus Center, Baltimore, MD 21202, USA
| | - Javier V Alvarez
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 E. Pratt Street, Columbus Center, Baltimore, MD 21202, USA
| | - J Sook Chung
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 E. Pratt Street, Columbus Center, Baltimore, MD 21202, USA.
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Lemos MFL, van Gestel CAM, Soares AMVM. Reproductive toxicity of the endocrine disrupters vinclozolin and bisphenol A in the terrestrial isopod Porcellio scaber (Latreille, 1804). CHEMOSPHERE 2010; 78:907-913. [PMID: 20015537 DOI: 10.1016/j.chemosphere.2009.10.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 10/21/2009] [Accepted: 10/27/2009] [Indexed: 05/28/2023]
Abstract
Endocrine Disruptor Compounds (EDCs) have been largely studied concerning their effects on vertebrates. Nevertheless, invertebrates as targets for these chemicals have been neglected and few studies are available. Specifically for edaphic invertebrates, data concerning the effects of EDCs is residual. Influences of EDCs on the reproduction systems of these organisms, with consequences at the population level, are expected but have not been confirmed. This work aimed to study the effects of bisphenol A (BPA) and vinclozolin (Vz) on the reproduction of the terrestrial isopod Porcellio scaber. Isopods were coupled and exposed to increasing concentrations of Vz and BPA and the females' reproductive cycle followed for 56d. Both compounds elicited reproductive toxicity. Vz and BPA decreased female reproductive allocation. Vz reduced pregnancy duration; increased the abortion percentage; decreased the number of pregnancies; and decreased the number of juveniles per female while BPA increased abortions at the lowest and highest test concentrations. The reproductive endpoints presented in here are indicative of the possible impact that this type of compounds might have on isopod population dynamics, which may eventually lead to population decline.
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Affiliation(s)
- M F L Lemos
- CESAM and Departamento de Biologia - Universidade de Aveiro, Portugal.
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Kunz PY, Kienle C, Gerhardt A. Gammarus spp. in aquatic ecotoxicology and water quality assessment: toward integrated multilevel tests. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 205:1-76. [PMID: 20044794 DOI: 10.1007/978-1-4419-5623-1_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The amphipod genus Gammarus is widespread and is structurally and functionally important in epigean freshwaters of the Northern Hemisphere. Its presence is crucial, because macroinvertebrate feeding is a major rate-limiting step in the processing of stream detrius. In addition, Gammarus interacts with multiple trophic levels bu functioning as prey, predator, herbivore, detritivore, and shredder. Such a broad span of ecosystem participation underlines the importance of Gammarus to pollutants and other disturbances may render it a valuable indicator for ecosystem health. This review summarizes the vast number of studies conducted with Gammarus spp. for evaluating aquatic ecotoxicology endpoints and examines the suitability of this native invertabrate species for the assessment of stream ecosystem health in the Northern Hemisphere. Numerous papers have been published on how pollutants affect gammarind behavior (i.e., mating, predator avoidance), reproduction, development, feeding activity, population structure, as well as the consequences of pollution on host-parasite, predator-prey, or native-invasive species interactions. Some biochemical and molecular biomarkers have already been established, such as the measurement of vitellogenin-like proteins, metallothioneins, alkali-labile phosphates (in proteins), and lipogenic enzyme activities for assessing endocrine distribution and detoxification mechanisms.
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Affiliation(s)
- Petra Y Kunz
- Ecotox Centre, Swiss Center for Applied Ecotoxicology, Eawag/EPFL, Uberlandstrasse 133, CH-8600, Dübendorf, Switzerland.
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Martin-Creuzburg D, Westerlund SA, Hoffmann KH. Ecdysteroid levels in Daphnia magna during a molt cycle: determination by radioimmunoassay (RIA) and liquid chromatography-mass spectrometry (LC-MS). Gen Comp Endocrinol 2007; 151:66-71. [PMID: 17222840 DOI: 10.1016/j.ygcen.2006.11.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Revised: 11/16/2006] [Accepted: 11/21/2006] [Indexed: 10/23/2022]
Abstract
Despite their abundance and their enormous significance for various ecological processes, endocrine systems of microcrustaceans have been poorly investigated. Here, we used a highly sensitive radioimmunoassay (RIA) to determine free and conjugated ecdysteroid levels in whole-body extracts of adult Daphnia magna during a complete molt cycle. Ecdysteroid levels were predominated by free ecdysteroids. Starting from basal levels in the postmolt stage the concentration of free ecdysteroids increased sharply in the early premolt stage, followed by a sharp decline back to basal levels just prior to ecdysis. Polar and apolar ecdysteroid conjugates were found in rather low amounts with little variation during the molt cycle. Only small amounts of ecdysteroids were found in newly deposited eggs of D. magna, which suggest a sparing investment of maternal ecdysteroids into the eggs for early embryogenesis. As in whole-body extracts, free ecdysteroids were the predominant ecdysteroids found in eggs of D. magna, together with small amounts of polar and intermediary amounts of apolar conjugates. Hence, the pathways leading to polar and apolar ecdysteroid conjugates appear to be of minor importance in D. magna. Analyses of the immunodetectable peak in free ecdysteroids by liquid chromatography-mass spectrometry (LC-MS) revealed that molting is induced most probably by an increased level of 20-hydroxyecdysone. Microcrustaceans of the genus Daphnia are key components in freshwater food webs. Examination of the functional role of ecdysteroids in controlling developmental processes might help to understand the performance of the herbivorous grazer in its environment, in particular with regard to the adverse effects of environmental xenobiotics acting as endocrine disrupters.
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Affiliation(s)
- Dominik Martin-Creuzburg
- Department of Animal Ecology I, Universitätsstrasse 30, University of Bayreuth, 95440 Bayreuth, Germany.
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Gagné F, Blaise C, Pellerin J. Altered exoskeleton composition and vitellogenesis in the crustacean Gammarus sp. collected at polluted sites in the Saguenay Fjord, Quebec, Canada. ENVIRONMENTAL RESEARCH 2005; 98:89-99. [PMID: 15721888 DOI: 10.1016/j.envres.2004.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 09/20/2004] [Accepted: 09/23/2004] [Indexed: 05/24/2023]
Abstract
Gammarus sp. individuals were collected at four intertidal sites subjected to direct sources of pollution (marinas, ferry traffic, and harbors) and at one site with no direct source of pollution. Levels of vitellogenin-like proteins (Vtg), metallothioneins (MT), alkali-labile phosphates (ALPs) in proteins, and lipogenic enzyme activities (i.e., glucose-6-dehydrogenase, isocitrate dehydrogenase, and malate enzyme) were measured in whole soft tissues. In exoskeletons, levels of pH-dependent extractable protein and chitin were determined to assess the possible impacts of pollution on exoskeleton integrity and the molting process. Results show that males were consistently heavier than females regardless of site quality but that the whole-body weight of both sexes was significantly lower at polluted sites. Females displayed either induced or decreased Vtg-like proteins at polluted sites, indicating significant changes in gametogenesis activity. MT levels were not sex dependent and tended to be induced at all impacted sites. ALP levels in acetone-fractionated proteins indicate altered phosphate mobilization at some impacted sites, where females tended to display higher ALP levels. Lipogenic enzyme activities did not vary by sex but were readily increased at impacted sites, suggesting a delay in gonad maturation rates. Exoskeleton protein characteristics revealed that the proportion of chitin in exoskeletons was a lower at most impacted site, suggesting disruption of chitin and pH-dependent protein mobilization. Principal component analysis revealed that gammarids collected at affected sites displayed substantial changes in the proportion of chitin, arthropodin, sclerotin, MTs, and intermediary glucose metabolism (glucose-6-phosphate dehydrogenase, and isocitrate dehydrogenase in soft tissues) and thus suffered from disturbed gametogenesis and exoskeleton integrity.
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Affiliation(s)
- F Gagné
- St. Lawrence Centre, Environment Canada, Research on Aquatic Ecosystems, 105 McGill Street, Montreal, Que., Canada H2Y 2E7.
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Gunamalai V, Kirubagaran R, Subramoniam T. Hormonal coordination of molting and female reproduction by ecdysteroids in the mole crab Emerita asiatica (Milne Edwards). Gen Comp Endocrinol 2004; 138:128-38. [PMID: 15302262 DOI: 10.1016/j.ygcen.2004.06.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Revised: 04/12/2004] [Accepted: 06/01/2004] [Indexed: 11/30/2022]
Abstract
The measurement of hemolymph ecdysteroids using radioimmunoassay (RIA) indicates a biphasic increase during intermolt and premolt stages of the mole crab Emerita asiatica. The gradual rise during intermolt stage corresponds to vitellogenic activities in the ovary; whereas a distinctive premolt peak is characteristic of molting crustaceans. Injection experiments with 20-hydroxyecdysone (20E) during different molt cycle stages revealed the onset of precocious premolt changes, as determined by the epidermal retraction and setal development. Injection of 20E augmented protein synthesis in the ovary, hepatopancreas and integumentary tissues. Quantification of ecdysteroids in different developmental stages of ovary also indicated a progressive increase of ovarian ecdysteroids. Interestingly, the ovarian ecdysteroids after reaching a peak at C3 stage, start declining drastically to reach the lowest level at D(3-4) stage. This decline in the ovarian ecdysteroids is inversely related to rising hemolymph ecdysteroids during these active premolt stages. The hatching of the embryos, attached to the pleopods of the ovigerous females also occurs under a high titer of hemolymph ecdysteroids. In support, 20E injection at C3 stage crabs indicated a significant reduction in time duration of pleopodal embryonic development leading to hatching of zoea larvae. Understandably, the augmented hemolymph ecdysteroid titer helps in the synchronization of embryo hatching and the premolt changes, as occurring under the normal premolt conditions.
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Affiliation(s)
- V Gunamalai
- Unit of Invertebrate Reproduction, Department of Zoology, University of Madras (Guindy Campus), Chennai 600 025, India
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Gagné F, Blaise C. Shell protein characteristics and vitellogenin-like proteins in brine shrimp Artemia franciscana exposed to municipal effluent and 20-hydroxyecdysone. Comp Biochem Physiol C Toxicol Pharmacol 2004; 138:515-22. [PMID: 15536059 DOI: 10.1016/j.cca.2004.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 08/20/2004] [Accepted: 08/24/2004] [Indexed: 11/18/2022]
Abstract
We developed biomarkers to monitor the endocrine-disrupting potential of contaminants and municipal effluents in aquatic arthropods. Artemia fransciscana shrimp were cultured and exposed to increasing concentrations of 20-hydroxyecdysone (20HE) and solid phase (C-8) municipal effluent extract (MEE) for 48 h at 20 degrees C. The levels of vitellogenin (Vtg)-like proteins, alkali-labile phosphates in total proteins and acetylcholinesterase (AChE) activity were determined in soft tissues. The levels of acid-soluble, alkali-soluble (sclerotin), neutral-soluble (arthropodin) proteins and chitin were determined to characterize the maturation state of shells. Both 20HE and the municipal effluent extract readily increased the total activity of acetylcholinesterase, alkali-labile phosphates in proteins and vitellogenin-like proteins in brine shrimp. In shells, 20HE and the effluent extract increased the proportion of chitin in shells and acid-soluble proteins but were not statistically significant for the latter. The proportion of sclerotin was increased by 20HE but was not changed by the effluent extract. The proportion of arthropodin was decreased by both 20HE and the effluent extract. Correlation analysis revealed that, as expected, the proportion of acid-soluble protein for biomineralisation and chitin levels were positively correlated and the proportion of arthropodin and sclerotin were negatively correlated in shells exposed to 20HE. Principal component analysis revealed that the proportion of chitin, arthropodin, sclerotin and acid-soluble proteins explained 63% of the responses. Shell protein and carbohydrate contents, controlled by the molting hormone 20HE, could be used as efficient markers for ecdysial properties of various contaminants. The municipal effluent appears to contain ecdysial-like chemicals that are capable of producing changes in shell protein composition that are similar to 20HE.
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Affiliation(s)
- F Gagné
- St. Lawrence Centre, Environment Canada, 105 McGill St., Montréal, Québec, Canada H2Y 2E7.
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Block DS, Bejarano AC, Chandler GT. Ecdysteroid concentrations through various life-stages of the meiobenthic harpacticoid copepod, Amphiascus tenuiremis and the benthic estuarine amphipod, Leptocheirus plumulosus. Gen Comp Endocrinol 2003; 132:151-60. [PMID: 12765655 DOI: 10.1016/s0016-6480(03)00062-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Endocrine function in arthropods has principally been characterized in insects and malacostracan crustaceans. However, meiofauna represent the most abundant metazoan marine taxa, with harpacticoid copepods comprising the second most abundant taxon. In addition, their diminutive biomass has made characterization of endocrine components difficult, so little is known about endocrine control of reproduction, molting, and growth in meiofauna. In this study, a sensitive fluorometric enzyme immunoassay (EIA) was utilized to quantify and compare the arthropod molting hormone, 20-hydroxyecdysone (20E), in various life-cycle and developmental stages of a laboratory reared meiobenthic copepod, Amphiascus tenuiremis, and in an amphipod, Leptocheirus plumulosus. In copepods, gravid females carrying late stage pre-hatch embryos contained significantly more 20E (390+/-252 fmol/female) than gravids carrying early (Stage-I) embryos (172+/-83 fmol/female). In contrast, ecdysteroid levels in Stage-I L. plumulosus gravid females (277+/-83 fmol/female) was greater than pre-hatch gravid females (146+/-42). Stage-I embryos of both copepods (19+/-10) and amphipods (11+/-5 fmol/embryo) possessed lower ecdysteroid content than copepod (35+/-15) and amphipod (43+/-33 fmol/embryo) pre-hatch embryos. Ecdysteroid levels were also assessed in naupliar, juvenile, adult male and non-gravid female copepod life-stages. In addition, ecdysteroids measured in field collected copepod species indicated gravid females possessed ecdysteroid levels similar to gravid A. tenuiremis. However, upon normalization of egg sac 20E content by brood size, embryos from larger broods contained lower levels of ecdysteroids when compared to embryos from smaller clutch sizes-indicating an inverse embryo/ecdysteroid relationship may exist across species.
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Affiliation(s)
- David S Block
- Department of Environmental Health Sciences, University of South Carolina, 800 Sumter Street, Room 311, Columbia, SC 29208, USA.
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Subramoniam T, Gunamalai V. Breeding biology of the intertidal sand crab, Emerita (Decapoda: Anomura). ADVANCES IN MARINE BIOLOGY 2003; 46:91-182. [PMID: 14601412 DOI: 10.1016/s0065-2881(03)46003-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Emerita is a burrowing mole crab or sand crab, adapted to life in wave-washed sandy beaches of temperate and tropical seas. The reproductive biology of this anomuran crab presents several peculiarities, all contributing to its adaptation to this harsh environmental niche. We discuss the following aspects: 1) sex ratio and size at sexual maturity, 2) neoteny and protandric hermaphroditism, 3) mating behaviour and sperm transfer strategy, 4) synchronisation of moulting and reproduction, 5) environmental impact on reproductive cycle and egg production, 6) biochemistry of yolk utilisation and energetics, 7) larval development, dispersal and settlement and 8) the value of Emerita as indicator species. These aspects are discussed in the light of the life history pattern, comprising a sedentary adult and pelagic larval phases. The successful colonisation of the physically challenging habitat of the sandy beach by Emerita is attributable largely to reproductive strategy and the larval developmental and recruitment pattern. Sensitivity to changing environmental conditions, including pollution, make this intertidal crab an indicator species for monitoring anthropogenic impact.
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Affiliation(s)
- T Subramoniam
- Unit of Invertebrate Reproduction and Aquaculture, Department of Zoology, University of Madras, Guindy Campus, Chennai-600 025, India.
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Warrier SR, Tirumalai R, Subramoniam T. Occurrence of vertebrate steroids, estradiol 17beta and progesterone in the reproducing females of the mud crab Scylla serrata. Comp Biochem Physiol A Mol Integr Physiol 2001; 130:283-94. [PMID: 11544073 DOI: 10.1016/s1095-6433(01)00385-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In crustaceans, vitellogenesis is known to be controlled by eyestalk neuropeptides, biogenic amines, ecdysteroids and a juvenile hormone-like compound, methyl farnesoate. In recent years, the occurrence of vertebrate steroid hormones, estradiol 17beta (E2) and progesterone (PG) has also been reported in a few decapods, although their precise role in female reproduction is yet to be determined. The levels of E2 and PG in the ovary, hepatopancreas and the hemolymph of the red mud crab, Scylla serrata were analyzed in different vitellogenic stages in order to establish a correlation between hormone profile and stages of vitellogenesis. It was observed that the levels of both the steroids increased steeply in the tissues at the onset of vitellogenesis (vitellogenic stage I). Maximum levels of estradiol were present in the hepatopancreas whereas the highest concentration of progesterone was seen in the ovary, suggesting dichotomous roles for these hormones in vitellogenesis. Furthermore, levels of these hormones were estimated in different embryonic stages of the eggs of the sand crab Emerita asiatica and mud crab S. serrata. Their levels fluctuated, following a definite pattern in the different stages, suggesting a possible functional role as morphogenetic hormones. This study, in addition, also reports the presence of E2 and PG on lipovitellin purified from ovary and eggs as well as vitellogenin purified from the hemolymph implicating a role for these lipoproteins as steroid carriers.
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Affiliation(s)
- S R Warrier
- Department of Zoology, Unit of Invertebrate Reproduction, University of Madras, Guindy Campus, Guindy, Madras-600 025, India
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Abstract
Lipovitellin II (Lv II), the major yolk protein of the anomuran crab Emerita asiatica, was purified using heparin-sepharose affinity column chromatography. The purified Lv II was a glycoprotein as it was stainable with periodic acid-Schiff's reagent. Quantitative analysis of sugars showed the presence of fucose, mannose, galactosamine, N-linked oligosaccharides, as well as O-linked oligosaccharides containing N-acetyl hexosamine as the terminal residue. The amount of N-linked oligosaccharides is higher than that of the O-linked oligosaccharides. Biogel P-4 column chromatographic separation of the radiolabeled oligosaccharides of Lv II showed the presence of five different O-linked oligosaccharides and four different N-linked oligosaccharide species. HPTLC separation of the neoglycolipids prepared from the O-linked oligosaccharides also showed the presence of five different O-linked oligosaccharide species. N-linked oligosaccharides contain significant quantities of mannose. Unisil column chromatographic purification in conjunction with HPTLC separation revealed three neutral glycolipid species such as monoglycosylceramide, diglycosylceramide, and triglycosylceramide in the Lv II. The functional significance of these carbohydrate components of the major yolk protein during embryogenesis of the sand crab is discussed.
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Affiliation(s)
- R Tirumalai
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
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Abstract
Ecdysteroids are the molting hormones in Crustacea, as in other arthropods. They also subserve functions in the control of reproduction and embryogenesis. The available evidence indicate that the ecdysteroids are sequestered into the ovary by binding to yolk precursor proteins. Steroidogenic ability of the ovary is yet to be demonstrated in Crustacea. Despite several investigations, the role of ecdysteroids in oocyte maturation is not fully known. However, the embryonic ecdysteroids undergo significant fluctuation, correlated to specific developmental stages, including the secretion of embryonic envelopes and cuticle. Ecdysteroid metabolism in the eggs seems to be active throughout embryogenesis inasmuch as the free ecdysteroids are rapidly converted into conjugates, and vice versa; in addition to their inactivation into excretory ecdysteroidic acids. Eyestalk neuropeptides such as molt inhibiting hormones have a dominant role on the ecdysteroid synthesis by Y-organ, although recent evidence suggests a stimulatory role for yet another endocrine gland, the mandibular organ on Y-organ synthesis.
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Affiliation(s)
- T Subramoniam
- Department of Zoology, Unit of Invertebrate Reproduction, University of Madras, Guindy campus, Guindy, 600 025, Madras, India.
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