In vitro methyl farnesoate secretion by mandibular organs isolated from different molt and reproductive stages of the crab Oziotelphusa senex senex

Nagaraju, Ganji Purnachandra; Reddy, P. Ramachandra

doi:10.1111/j.1444-2906.2006.01164.x

Cited by 45 publications

(37 citation statements)

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“…This observation correlates with the high TIs of red-phase animals, consistent with the idea that MF stimulates testicular growth either directly or indirectly in crustaceans (Kalavathy et al, 1999;Nagaraju et al, 2003;Nagaraju et al, 2006;Reddy et al, 2004). These observations are similar to previous studies in the spider crab (Libinia emarginata), which demonstrated a correlation between the reproductive status of males and MF synthesis by the mandibular organ (MO) and hemolymph levels of MF (Sagi et al, 1993;Sagi et al, 1994).…”

Section: Discussionsupporting

confidence: 81%

Methyl farnesoate couples environmental changes to testicular development in the crabCarcinus maenas

Nagaraju

Borst

2008

Journal of Experimental Biology

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SUMMARYCarcinus maenas males have two major color phases. Green-phase males molt frequently and tend to live in brackish estuaries during the summer. After becoming red-phase males, they molt infrequently, have higher mating success, and live in cooler, deeper water. We found profound differences between these two phases in the way salinity and temperature affect hemolymph levels of methyl farnesoate (MF), a hormone that affects crustacean reproduction. Few green-phase males (<10%) had detectable MF in 33 ppt seawater (SW) at 11 or 18°C. By contrast, about 30% of the red-phase males had detectable MF at either temperature. After transfer to 5 ppt SW, none of the green-phase males had detectable MF at 11°C whereas 100% of green-phase males did at 18°C. By contrast, 100% of the red-phase males had detectable MF in 5 ppt SW at either temperature. At 11°C, green-phase males had detectable MF after eyestalk ablation (ESA), showing that they can produce MF. There was no additional increase in MF levels when ESA animals of either color phase were transferred to 5 ppt SW, suggesting that the eyestalk is the primary regulator of the MF response to low salinity. MF levels of green-phase males were increased by injecting MF, by ESA, or by exposure to 5 ppt SW at 18°C. The testicular index of these treated animals nearly doubled after two weeks. Our results strongly suggest that environmental conditions such as temperature and salinity, affect testicular development in this crab by changing its MF levels.Key words: methyl farnesoate, testis, crustacean, salinity, reproduction, temperature. THE JOURNAL OF EXPERIMENTAL BIOLOGY 2774In the present study, we show that red-phase crabs are more likely to have detectable MF in their hemolymph than green-phase crabs. In addition, the testicular index (TI) of red-phase animals is higher than that in green-phase animals. Furthermore, our results indicate that environmental factors differentially affect MF levels in the two color phases. These results are consistent with the hypothesis that MF stimulates testicular development. To test this hypothesis, we show that environmental factors that increase MF levels also stimulate testicular development. The MF levels in these two color phases appear to be responsible, in part, for the different reproductive activities of these males. MATERIALS AND METHODS AnimalsCrabs [Carcinus maenas (Linnaeus 1758)] were generously provided by Dan Landers (Millstone Environmental Lab; Waterford, CT, USA). Most of the males used in this study were 50±5 g (carapace width, CW 5.2±0.6 cm) and were collected during the spring and early summer. Green-phase and red-phase animals were identified by the color of their ventral surface (Reid et al., 1997). None of the experimental animals was missing appendages. At the end of some experiments, the testes were removed and weighed, and the TI (% total body mass) was calculated. Crabs were kept in large tanks containing artificial SW (Instant Ocean, Spectrum Brands; Atlanta, GA, USA) at normal salinity (33 ppt) at 11 o...

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Section: Discussionsupporting

confidence: 81%

Methyl farnesoate couples environmental changes to testicular development in the crabCarcinus maenas

Nagaraju

Borst

2008

Journal of Experimental Biology

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“…In vitro, MF production has been associated with ovarian development in C. maenas, L. emarginata and U. pugilator Laufer et al, 1987). Similarly, in vivo MF levels have been correlated with ovarian maturation and molting in the crab O. senex senex (Nagaraju et al, 2006). Administration of MF increased the Vg titer in hemolymph of ESA spider crab (Vogel and Borst, 1989).…”

Section: Mfmentioning

confidence: 99%

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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“…The physiological function for MF was enigmatic in crustaceans until its analogy with the gonadotropic hormone JH III from insects was established ); a recent report suggests MF to be the precursor for insect JH (Teal et al 2014). In vitro and in vivo experiments have demonstrated an association between MF production and ovarian development in C. maenas, Libinia emarginata, and Procambarus clarkii , Laufer et al 1998, Nagaraju et al 2006, Nagaraju 2011. Recent studies on the biosynthesis and release of farnesoic acid and MF within the gland (MO) revealed that the rates of biosynthesis of FA and MF were stagedependent, with maximal production (with a threefold increase) occurring during secondary vitellogenesis, i.e., stages 4 and 5 in Homarus americanus (Tiu et al 2012).…”

Section: Introductionmentioning

confidence: 99%

“…A major limitation in investigating the exact role of MO has been its anatomical location which has made its surgical removal difficult. Therefore, it has not been possible to perform the 'classical' ablation-replacement experiments to probe into the MO function, unlike the situation in the corpora allata of insects (Nagaraju et al 2006). …”

Section: Introductionmentioning

confidence: 99%

Secretory activity of mandibular organ fluctuates in response to reproductive season of the field crab Paratelphusa sp. (Brachyura; Decapoda): an ultrastructural study

2014

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Background: Mandibular organ (MO) in decapods is suggested to play regulatory role in reproduction, in few species; however, MO is considered to control growth. The present study addresses this question by an ultrastructural study on the MO of the field crab, Paratelphusa sp. Our sampling for consecutive years (2008 to 2012) revealed that Paratelphusa sp. devotes July to October for reproduction, judged by the occurrence of growing ovaries and the berried females. From November to the succeeding June, the females are in a state of reproductive arrest (non-reproductive period); ovaries during this season would appear as white bands with no signs of yolk deposition.Results: Morphologically, MO of Paratelphusa sp. is positioned posterior to the mandibles and is in close apposition with the distal end of the mandibular apodeme. MO of Paratelphusa sp. exhibited significant levels (t = 8.097, P < 0.0001, N = 10) of season-dependent size variations. Our electron microscopic observations reveal that the MO is highly secretory during the reproductive period, evidenced by the occurrence of sacculated Golgi bodies having dense inclusions, several mitochondria with tubular cristae, and extensive networks of SER and rough endoplasmic reticulum (RER). During the non-reproductive period, however, the MO is least active; RER, the mitochondria, and the Golgi are only sparsely seen. Interestingly, the plasma membrane exhibits a highly convoluted appearance all the way through the non-reproductive period.Conclusions: The present study reveals that the secretory activity of MO of Paratelphusa sp. is entrained with reproductive activity. The existence of a high correlation between MO secretory activity and ovarian growth implicates the former's role in reproduction.

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In vitro methyl farnesoate secretion by mandibular organs isolated from different molt and reproductive stages of the crab Oziotelphusa senex senex

Cited by 45 publications

References 32 publications

Methyl farnesoate couples environmental changes to testicular development in the crabCarcinus maenas

Methyl farnesoate couples environmental changes to testicular development in the crabCarcinus maenas

Reproductive regulators in decapod crustaceans: an overview

Secretory activity of mandibular organ fluctuates in response to reproductive season of the field crab Paratelphusa sp. (Brachyura; Decapoda): an ultrastructural study

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