The Y-organ secretory activity fluctuates in relation to seasons of molt and reproduction in the brachyuran crab, Metopograpsus messor (Grapsidae): Ultrastructural and immunohistochemical study (original) (raw)
Related papers
Zoological studies
Hemolymph ecdysteroid titers in a brachyuran crab Uca triangularis that concomitantly undergoes molting and reproduction. Zoological Studies 51(7): 966-976. Investigations conducted thus far suggest that premolt growth and ovarian growth are antagonistic events in brachyuran crabs, arguably implying that yolk deposition does not occur during premolt when the ecdysteroid titer is very high. The present paper examines ecdysteroid levels in a brachyuran crab Uca triangularis that exhibits simultaneous programming of premolt growth and reproduction during certain seasons of the year. The species exhibits 2 patterns of breeding cycles, 1 (premolt breeding cycle) synchronous with the premolt cycle during Feb.-May, and the other (intermolt breeding cycle) taking place only during intermolt (Aug.-Jan.); no breeding activity occurs during June-July. Results depicted in the present paper are also expected to help us evaluate the possible role of ecdysteroids in reproduction in crustaceans, a ...
Zoological Studies, 2014
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
Metopograpsus messor, a brachyuran crab inhabiting the estuaries of North Kerala (India), is a prolific breeder releasing approximately 14-16 broods a year. The present paper reports the sequence information on the DNA binding domain (C domain, DBD), linker (D domain) and ligand binding domain (E domain, LBD) of M. messor ecdysteroid receptor (MmEcR) gene, the first grapsid brachyuran crab EcR examined. We have also measured MmEcR transcript levels in the ovary and the hepatopancreas throughout the annual cycle, with special reference to seasons of molt and reproduction. MmEcR expression in both the tissues is found to be at its peak (P < 0.05) in late premolt crabs (January/May, molt/reproduction season); the expression levels are lowest (P < 0.05) during June/July, when the females would neither molt nor reproduce (season for molt/reproduction repose). Intermediate levels of expression were found during the breeding season (August/December). Interestingly, this pattern of gene expression is in concordance with the fluctuating ecdysteroid levels of the hemolymph and Y organ secretory activity. The significant levels of fluctuation in the ovarian expression of MmEcR strongly suggest the ovary as a potential target for ecdysteroid action. A season-wise comparison of the gene expression reveals that ovarian MmEcR transcript levels are higher in breeding crabs (August/December) than the non-breeding animals (June/July), implicating a possible ecdysteroid role in reproduction in M. messor.
Effect of moult-inhibiting hormone on ketodiol conversion by crab Y-organs
Journal of Insect Physiology, 1988
Ketodiol incubated in vitro witli &minus mamas Y-organs, is converted into three molecules 22,25-dideoxyecdysone, 25deoxyecdysone and ecdysone. Two of these three products (25deoxyecdysone and ecdysone) are secreted into the medium and are possible precursors of ponasterone A and 20-hydroxyecdysone respectively, the major haemolymph ecdysteroids. The ratio of ecdysone to 25-deoxyecdysone varies during the moulting cycle of the animal; no conversion occurs in intermoult crabs (C4), in premoult crabs (Dl), 25-deoxyecdysone is the predominant ketodiol metabolite whereas in crabs in the stage DO (apolysis period) the predominant metabolite is ecdysone. The regulation of ecdysteroid synthesis is achieved by moult-inhibiting hormone stored and released by the sinus glands. The sinus gland extracts and purified moult-inhibiting hormone were tested for their effect on ketodiol conversion by crab Y-organs. The effects of the sinus gland extract or moult-inhibiting hormone on synthesis of ecdysone and 25-deoxyecdysone depend on the moulting stage. In crabs in which 2%deoxyecdysone is the predominant metabolite, sinus gland extracts of the hormone inhibit ketodiol conversion into 25-deoxyecdysone and, at higher concentration, its conversion into ecdysone. In crabs in which ecdysone is the predominant compound, its level decreases as the concentration of sinus gland extract or moult-inhibiting hormone is increased.
Cell and Tissue Research, 1980
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.
Arthropod Structure & Development, 2001
The production of ecdysteroid molting hormones by crustacean Y-organs is negatively regulated by a neuropeptide, molt-inhibiting hormone. It is generally agreed that molt-inhibiting hormone is produced and released by the eyestalk neuroendocrine system. In the present study, immunocytochemical methods were used to detect molt-inhibiting hormone immunoreactive neurons in eyestalk ganglia of the blue crab, Callinectes sapidus. The primary antiserum used was generated against molt-inhibiting hormone of the green shore crab, Carcinus maenas. A preliminary Western blot analysis indicated the antiserum binds molt-inhibiting hormone of Callinectes sapidus. Using confocal and conventional immuno¯uorescence microscopy, molt-inhibiting hormone immunoreactivity was visualized in whole mounts and thin sections of Callinectes sapidus eyestalk ganglia. Immunoreactivity was detected in 15±25 neurosecretory cell bodies in the medulla terminalis X-organ, their associated axons and collateral branches, and their axon terminals in the neurohemal sinus gland. The cellular organization of molt-inhibiting hormone immunoreactive neurons in blue crabs is generally similar to that reported for other crab species. The combined results suggest the cellular structure of the molt-inhibiting hormone neuroendocrine system is highly conserved among brachyurans. q
Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2011
Decapod crustaceans show proliferation of the nerve cells in the olfactory lobe throughout their lives. However, the regulation of this process is still poorly understood, since it may vary with endogenous and exogenous factors. The objective of the present investigation was to quantify the proliferation of nerve cells and number of nerve cells with ecdysone receptors in the clusters of the central olfactory system in Neohelice granulata, according to moult stages and in different seasons (summer and winter). Three injections of bromodeoxyuridine (BrdU) were administered to the crabs. Brains were sectioned by microtome and fixed on slides for immunohistochemistry with anti-BrdU and anti-EcR antibodies. The proliferation of nerve cells was higher in winter than in summer, probably because in winter the crabs do not breed and the premoult and postmoult periods are longer. Crabs in postmoult exhibited more BrdU-labelled cells than crabs in premoult or intermoult in winter, because of a greater number of mitoses related to an increase in body size and addition of olfactory receptor neurons. The number of EcR-labelled cells was higher in premoult than in postmoult or intermoult in winter. The proliferation of nerve cells is regulated seasonally and according to moult stages.
Histoanatomy of Androgenic Gland of a Brachyuran Crab , Parasesarma Plicatum ( Latrielle , 1803 )
2016
The present study was executed on the androgenic gland of mangrove crab Parasesarma plicatum to study the morphology, histology and its function in male reproduction. Morphologically, the androgenic gland is attached to wall of the ejaculatory duct. The light microscopic study showed two cell types. Type 1 cells are small with large nucleus and small amount of cytoplasm. Type 2 cells occupy more space in the glandular region. These are larger cells with basophilic nuclei and involve in secretary activity. This suggests the function of androgenic gland in male reproduction of crabs.