Methyl Farnesoate Stimulates Ecdysteroid Secretion from Crab Y-Organs in Vitro

Tamone, Sherry L.; Chang, Ernest S.

doi:10.1006/gcen.1993.1050

Cited by 127 publications

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“…Further studies indicated that MF, fenoxycarb and pyriproxyfen all disrupted ecdysteroid-regulated aspects of embryo development in daphnids (Mu and LeBlanc, 2004). The data indicate that MF modulates ecdysteroid activity in crustaceans (Tamone and Chang, 1993). Further studies are needed to verify the other physiological roles of MF in microcrustaceans.…”

Section: Non-neuroendocrine Regulation Of Reproduction In Microcrustamentioning

confidence: 90%

Reproductive regulators in decapod crustaceans: an overview

Nagaraju

2011

Journal of Experimental Biology

271

170

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SummaryControl of reproductive development in crustaceans requires neuropeptides, ecdysone and methyl farnesoate (MF). A major source of neuropeptides is the X-organ-sinus gland (XO-SG) complex located in the eyestalk ganglia of crustaceans. The other regulatory factors (either peptides or neuromodulators) are produced in the brain and thoracic ganglia (TG). Two other regulatory non-peptide compounds, the steroid ecdysone and the sesquiterpene MF, are produced by the Y-organs and the mandibular organs, respectively. In the current review, I have tried to recapitulate recent studies on the role of gonadal regulatory factors in regulating crustacean reproduction.Key words: crustaceans, reproduction, gonads, X-organ-sinus gland, peptides. THE JOURNAL OF EXPERIMENTAL BIOLOGY4 crustaceans, the testis contains 10-15 lobes each composed of many seminiferous tubules, whose shape changes according to the stage of spermatogenesis. Spermatogenesis starts in the undifferentiated seminiferous tubules (proacini) at the top of each lobe. Meiotic activity occurs in the acini that develop proacini somewhat proximally from the top of each lobe. In this stage, the lobules contain mostly primary spermatocytes. Differentiation of secondary spermatocytes and spermatids takes place in the seminiferous tubules, which lie in the center of each lobe. All these seminiferous tubules are filled with spermatocytes and spermatids surrounded by a layer of otheocytes of mesodermal origin. The hormonal control of spermatogenesis is not completely understood in crustaceans. There is information on MF as a reproductive hormone in males. The female reproductive systemThe reproductive system of female crustaceans consists of the paired ovaries, oviducts, gonophores and an external sperm reception area. The ovarian lobes are connected by a central bridge of ovarian tissue (Fig.1D). The ovarian lobes are symmetrically arranged and lie in the cephalothorax on the top of the stomach and hepatopancreas (HP). An oviduct arises laterally from each ovary at a point just beside the position of the heart. It extends ventrally and opens through a gonophore in the abdomen. In sexually receptive females, each pore is equipped with a large tuft of long setae, which apparently serve as a tube for the passage of ova. In the fully mature state, the shapes of ovarian limbs can be distinguished only with difficulty as the ovary fills the thoracic region of the body cavity completely.In the majority of female Malacostraca, oogonial proliferation and ovarian differentiation take place when the ovary is translucent to opaque white (previtellogenic ovary). During vitellogenesis the color of the ovary changes from pale yellow (vitellogenic stage I) to orange (vitellogenic stage II) and it then becomes brown (vitellogenic stage III) to dark brown prior to spawning. Maturation of the ovary also includes an increase in the size of the ovary as the oocytes proliferate and increase in diameter, due to yolk deposition. Role of neuropeptides in reproductionThe hormonal control o...

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Section: Non-neuroendocrine Regulation Of Reproduction In Microcrustamentioning

confidence: 90%

Reproductive regulators in decapod crustaceans: an overview

Nagaraju

2011

Journal of Experimental Biology

271

170

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“…Similarly, elevated daphnia RXR mRNA levels early in embryo development co-occur with elevated ecdysteroid levels, which may indicate induction of RXR by ecdysteroids. Furthermore, Tamone & Chang (1993) reported that MF stimulates ecdysteroid secretion from crab Y-organs in vitro. These studies potentially indicate that MF is the upstream signaling molecule of ecdysteroid and RXR.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning and sequence of retinoid X receptor in the green crab Carcinus maenas: a possible role in female reproduction

Nagaraju

Rajitha

Borst³

2011

Journal of Endocrinology

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Retinoid X receptor (RXR) belongs to an ancient superfamily of nuclear hormone receptors, and plays an important role in reproduction of vertebrates. However, the reproductive role of RXR has not been clarified in crustaceans. In this investigation, we first report the cloning of two alternative splice variants of RXR cDNA from green crab ovarian RNA. RXR mRNA levels were quantified in different vitellogenic stages of the crab hepatopancreas (HP) and ovary. The expression of RXR mRNA relative to the arginine kinase mRNA was significantly increased in the HP of vitellogenic crabs in a stage-dependent manner. The relative levels of RXR mRNA in the ovary were significantly lower in vitellogenic stage III crabs than in crabs in the other three stages. These data indicate that the HP and ovary of the crab are capable of expressing RXR, which may regulate, in part, vitellogenesis in the crab. We also examined the effects of methyl farnesoate (MF) and RXR-dsRNA treatments on vitellogenin and RXR gene expression. Vitellogenin and RXR mRNA levels in HP and ovarian fragments incubated in MF were significantly (P!0 . 001) higher than in control tissue fragments prepared from the same animal. Treatment of crabs with RXR-dsRNA significantly (P!0 . 001) reduced mRNA levels for RXR and for vitellogenin as well as MF levels in hemolymph. These results indicate that, MF and RXR form a complex (MF-RXR) directly and together stimulate ovarian development in these green crabs. This interaction of RXR, MF, and ovary development axis is a novel finding and is the first report to the best of our knowledge.

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“…epidermis and hepatopancreas) of crustaceans (Chang & O'Connor 1988). Synthesis of ecdysone is under hormonal control from moulting inhibitory hormone and methyl farnesoate (Tamone & Chang 1993) and could therefore be potentially sensitive to environmental steroids and their mimics.…”

Section: Discussionmentioning

confidence: 99%

Endocrine disruption in the shore crab Carcinus maenasa biomarker for benthic marine invertebrates?

Lye

Bentley²,

Clare³

et al. 2005

Mar. Ecol. Prog. Ser.

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A considerable amount of research has been conducted on the effects of certain contaminants that have the potential to impact the endocrine systems that regulate vital life processes in freshwater and marine fishes. There is, however, a relative paucity of information on aquatic and especially benthic marine invertebrate species, many of which could be seriously impacted by sewage effluent and industrial discharges. The present study used a combination of end-points to assess possible endocrine disruption in a marine crustacean, the shore crab Carcinus maenas. These included pheromonally mediated sexual behaviour, exoskeletal morphological measures, quantities of steroid moulting hormones (i.e. ecdysteroids) and the presence of the egg yolk protein, vitellin in male crabs. Crabs were collected from sites known to elicit high oestrogenic responses in vertebrates and also from coastal reference sites. The results suggest that shore crabs around the coast of the Great Britain show effects consistent with pollutant-mediated endocrine disruption. These include a reduced behavioural response to the female sex pheromone, morphometric abnormalities such as reduced pleopod-length ratios and enlarged abdomen width, enhanced steroid moulting-hormone (ecdysone equivalent) levels and the detection of vitellin-like proteins in the hepatopancreas of male crabs. This multilevel approach may have significant potential for investigating endocrine disruption in marine crustaceans.KEY WORDS: Endocrine disruption · Shore crab · Vitellin · Ecdysteroids · Sex pheromone · Morphology · Biomarker Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 288: [221][222][223][224][225][226][227][228][229][230][231][232] 2005 land (Moore & Stevenson 1991, 1994, the occurrence of intersex in a population of lobsters exposed to sewage effluent (Sangalang & Jones 1997), masculinisation of freshwater copepod species in North American lakes (Sillett & Stemberger 1998) and the presence of dual-gender imposex in freshwater crabs inhabiting Japanese TBT-uncontaminated mountain streams (Takahashi et al. 2000). Gross et al. (2001) reported that high numbers of females displayed abnormal vitellogenic oocytes and a reduced male/female size differential in amphipods (Gammarus pulex) found below sewage treatment works known to contain endocrine-disrupting chemicals in their effluent.Investigations into endocrine disruption in invertebrates have mainly focused on the potential influence of vertebrate-type hormones (e.g. oestrogens) and their analogues. There is little direct evidence that natural and anthropogenic compounds, which are capable of modifying endocrine control in vertebrates, have similar effects on invertebrates such as crustaceans (Breitholtz & Bengtsson 2001). For example, the endocrine processes associated with vitellogenesis in crustaceans are not influenced by environmental contaminants in the same way as in fishes. Thus, neither vtg nor its corresponding egg yolk protein vitellin (vt) ...

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Methyl Farnesoate Stimulates Ecdysteroid Secretion from Crab Y-Organs in Vitro

Cited by 127 publications

References 0 publications

Reproductive regulators in decapod crustaceans: an overview

Reproductive regulators in decapod crustaceans: an overview

Molecular cloning and sequence of retinoid X receptor in the green crab Carcinus maenas: a possible role in female reproduction

Endocrine disruption in the shore crab Carcinus maenasa biomarker for benthic marine invertebrates?

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Methyl Farnesoate Stimulates Ecdysteroid Secretion from Crab Y-Organs in Vitro

Cited by 127 publications

References 0 publications

Reproductive regulators in decapod crustaceans: an overview

Reproductive regulators in decapod crustaceans: an overview

Molecular cloning and sequence of retinoid X receptor in the green crab Carcinus maenas: a possible role in female reproduction

Endocrine disruption in the shore crab Carcinus maenasa biomarker for benthic marine invertebrates?

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Endocrine disruption in the shore crab Carcinus maenasa biomarker for benthic marine invertebrates?