Ontogeny of salinity tolerance and hyper-osmoregulation by embryos of the intertidal crabs Hemigrapsus edwardsii and Hemigrapsus crenulatus (Decapoda, Grapsidae): Survival of acute hyposaline exposure

Taylor, H. H.; Seneviratna, Deepani

doi:10.1016/j.cbpb.2005.03.005

Cited by 34 publications

(34 citation statements)

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“…We showed previously (Taylor and Seneviratna, 2005) that post-gastrula stages survived acute transfer to seawater diluted 100-fold and remained hyperosmotic to the external medium for several days. In the present study, embryonic osmolality initially decreased on transfer to dilute seawater but was then maintained hyperosmotic to the medium for several weeks.…”

Section: Discussionmentioning

confidence: 93%

“…Crabs were removed briefly, a small sample of the eggs was detached from the pleopods for microscopical examination, and the crab replaced. The developmental stage of embryos is reported on a five-step scheme (Taylor and Seneviratna, 2005) (Fig.·1). The approximate timings of these stages in 100% seawater at 15°C are for H. sexdentatus: (1) cleavage, 0-5·days; (2) gastrula, 6-28·days; (3) eyespot, 29-37·days; (4) four-lobe, 38-50·days; (5) two-lobe to hatching zoea, 51-62·days.…”

Section: Methodsmentioning

confidence: 99%

“…Egg volume (V) was calculated from the largest (D) and smallest (d) diameters of 25 eggs from each crab using a stereomicroscope equipped with a micrometer eye-piece (V=d 2 D/6). The osmolalities of 10·l sub-samples from ~0.2·g of homogenized eggs (Taylor and Seneviratna, 2005) and of the seawater were determined by vapour pressure osmometry (Wescor 5100, Logan, UT, USA).…”

Section: Methodsmentioning

confidence: 99%

“…Crabs in 100% seawater were sampled immediately and the remainder maintained at 15°C and removed at either stage 4 or stage 5. The Na + /K + -ATPase activity was measured on ~0.4·g of homogenized eggs (less than five samples in each stage and salinity combination) as described previously (Taylor and Seneviratna, 2005) …”

Section: Effectmentioning

confidence: 99%

“…transfer to seawater diluted by as much as 100-fold (~10·mmol·kg -1 osmolality) for several days without significant mortality or obvious impairment of development (Taylor and Seneviratna, 2005). During this time, the internal osmolality of these eggs (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Ontogeny of osmoregulation in embryos of intertidal crabs(Hemigrapsus sexdentatusandH. crenulatus, Grapsidae,Brachyura): putative involvement of the embryonic dorsal organ

Seneviratna

Taylor

2006

Journal of Experimental Biology

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SUMMARY This study examined whether the existence of hyperosmotic internal fluids in embryos of euryhaline crabs (Hemigrapsus sexdentatus and H. crenulatus) in dilute seawater reflects osmotic isolation due to impermeability of the egg envelope, as proposed for other decapods, or active osmoregulation. When ovigerous crabs with eggs at gastrula stage were transferred from 100% seawater (osmolality 1000 mmol kg–1) to 50% seawater, embryogenesis and hatching of zoea were completed normally, but were delayed. Hatching failed if the transfer to 50% seawater occurred before gastrulation, and embryogenesis was abnormal in 25% seawater. In 100%seawater, embryos at all stages were internally hyperosmotic by 150–250 mmol kg–1. On transfer to 50% seawater, osmolality initially decreased but remained 200–350 mmol kg–1 hyperosmotic to the medium for several weeks until hatching. High efflux rates of tritium-labelled water (t1/2 16–75 min)and 22Na (t1/2 109–374 min) from H. crenulatus embryos were inconsistent with the osmotic isolation hypothesis. It is concluded that post-gastrula embryos were actively hyper-osmoregulating. The diffusional water permeability of the embryos decreased during development while the sodium efflux rate increased 10-fold. Very rapidly exchanging pools of water and sodium (t1/2 a few seconds to minutes) probably corresponded to peri-embryonic fluid and implied that the egg envelope was a negligible barrier to diffusion of water and salts. Higher Na+/K+-ATPase activities in late embryos of H. crenulatus incubated in 50% seawater than in embryos incubated in full strength seawater were consistent with an acclimation response. An area of the embryonic surface located over the yolk in the region of the embryonic dorsal organ stained with AgNO3. Staining appeared at gastrulation, persisted throughout development and was lost at hatching. Deposits of AgCl between the outer and inner membranes, identified by X-ray microanalysis, suggest that the dorsal organ was a site of chloride extrusion. A model for osmoregulation in post-gastrula embryos is proposed: osmotic uptake of water is balanced by excretion of water and salts via the dorsal organ and salt loss is balanced by active uptake over the general embryonic ectoderm.

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Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ontogeny of osmoregulation in embryos of intertidal crabs(Hemigrapsus sexdentatusandH. crenulatus, Grapsidae,Brachyura): putative involvement of the embryonic dorsal organ

Seneviratna

Taylor

2006

Journal of Experimental Biology

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Do osmoregulators have lower capacity of muscle water regulation than osmoconformers? A study on decapod crustaceans

et al. 2010

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Decapod crustaceans occupy various aquatic habitats. In freshwater they are osmoregulators, while marine species are typically osmoconformers. Freshwater crustaceans are derived from marine ancestors. The hypothesis tested here was that osmoregulators, which can rely on salt transport by interface epithelia to prevent extracellular disturbance, would have a lower capacity of tissue water regulation when compared with osmoconformers. Four species of decapod crustaceans (the marine osmoconformer crab Hepatus pudibundus, and three osmoregulators of different habitats) have been exposed in vivo to a salinity challenge, for up to 24 hr. Osmoregulators were: the estuarine shrimp Palaemon pandaliformis, the diadromous freshwater shrimp Macrobrachium acanthurus, and the hololimnetic red crab Dilocarcinus pagei. H. pudibundus displayed hemolymph dilution already after 0.5 hr in 25 per thousand, reaching approximately 30% reduction in osmolality, but its muscle degree of hydration did not increase. To make the different in vivo salinity challenges directly comparable, the ratio between the maximum change in muscle hydration with respect to the control value measured for the species and the maximum change in hemolymph osmolality was calculated (x 1,000): H. pudibundus (25 per thousand, 8.1% kg H(2)O/mOsm x 10(3))>P. pandaliformis (2 per thousand, 9.2)>M. acanthurus (30 per thousand, 12.6)>P. pandaliformis (35 per thousand, 16.7)>D. pagei (7 per thousand, 60.4). Muscle slices submitted in vitro to a 30% osmotic challenge confirmed in vivo results. Thus, the estuarine/freshwater osmoregulators displayed a lower capacity to hold muscle tissue water than the marine osmoconformer, despite undergoing narrower variations in hemolymph osmolality.

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Gill Ion Transport ATPases and Ammonia Excretion in Aquatic Crustaceans

Leone

Lucena

Garçon

et al. 2016

Acid-Base Balance and Nitrogen Excretion in Invertebrates

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Ontogeny of salinity tolerance and hyper-osmoregulation by embryos of the intertidal crabs Hemigrapsus edwardsii and Hemigrapsus crenulatus (Decapoda, Grapsidae): Survival of acute hyposaline exposure

Cited by 34 publications

References 46 publications

Ontogeny of osmoregulation in embryos of intertidal crabs(Hemigrapsus sexdentatusandH. crenulatus, Grapsidae,Brachyura): putative involvement of the embryonic dorsal organ

Ontogeny of osmoregulation in embryos of intertidal crabs(Hemigrapsus sexdentatusandH. crenulatus, Grapsidae,Brachyura): putative involvement of the embryonic dorsal organ

Do osmoregulators have lower capacity of muscle water regulation than osmoconformers? A study on decapod crustaceans

Gill Ion Transport ATPases and Ammonia Excretion in Aquatic Crustaceans

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