Organic Osmolytes in Elasmobranchs

Yancey, Paul H.

doi:10.1016/b978-0-12-801286-4.00004-6

Cited by 12 publications

(11 citation statements)

References 178 publications

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“…DMG was only effective at the highest concentration tested, 1000 mmol l −1 , and glycine was generally ineffective at inhibiting unraveling over the entire concentration range tested. This pattern of stabilization, TMAO>betaine>DMG>glycine, is consistent with other studies showing that an increased degree of methylation increases stabilizing ability and that of the two trimethylamines, TMAO is typically stronger than betaine (Yancey, 2005(Yancey, , 2015Street et al, 2006).…”

Section: Discussionsupporting

confidence: 91%

“…Hagfishes are a diverse group of animals whose 76 described species (Knapp et al, 2011) inhabit a massive depth range, from the relatively shallow inshore hagfish (Eptatretus burgeri), which has been caught at 10 m, to the black hagfish (Eptatretus deani), which can live at depths greater than 2700 m (Fernholm, 1998). It would be interesting to see whether hagfishes follow the trend of increasing TMAO levels with depth, in both their tissues and blood, as well as in their slime glands, where levels are already high (Yancey, 2015). The two species for which we have data on organic osmolyte concentration in the slime glands, E. stoutii and M. glutinosa, have similar depth ranges and therefore are not informative on this issue.…”

Section: Discussionmentioning

confidence: 99%

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High concentrations of trimethylamines in slime glands inhibit skein unraveling in Pacific hagfish

Jain

Starksen

Singh

et al. 2019

Journal of Experimental Biology

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Hagfish defend themselves from fish predators by producing large volumes of gill-clogging slime when they are attacked. The slime consists of seawater and two major components that are ejected from the slime glands: mucus and threads. The threads are produced within specialized cells and packaged into intricately coiled bundles called skeins. Skeins are kept from unraveling via a protein adhesive that dissolves when the skeins are ejected from the slime glands. Previous work revealed that hagfish slime glands have high concentrations of methylamines including trimethylamine N-oxide (TMAO), trimethylglycine (betaine) and dimethylglycine (DMG); however, the function of these compounds in the slime glands is unknown. We hypothesized that methylamines have stabilizing effects on the skeins that prevent premature unraveling in the gland. To test this hypothesis, we quantified the effect of methylamines on skein unraveling in Pacific hagfish and found that TMAO and betaine have inhibitory effects on skein unraveling in vitro. Furthermore, we found that TMAO is a more effective inhibitor of unraveling than betaine, but the presence of TMAO synergistically boosts the inhibitory action of betaine. Glycine and DMG were far less effective inhibitors of unraveling at natural concentrations. Our results support the hypothesis that high levels of trimethylamines in the slime glands may act to hold the coiled thread skeins together within gland thread cells, and they may do so by stabilizing adhesive proteins. These results advance our knowledge of skein stabilization and deployment and provide yet another example of trimethylamines functioning to stabilize proteins in a marine organism.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

High concentrations of trimethylamines in slime glands inhibit skein unraveling in Pacific hagfish

Jain

Starksen

Singh

et al. 2019

Journal of Experimental Biology

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“…An aliquot of sperm extracted in vivo from small spotted catshark (S. canicula), and post-mortem from rough skate (R. radula), common stingray (Dasyatis pastinaca), blue shark (Prionace glauca) and bull ray (A. bovinus) was centrifuged to obtain the seminal plasma and evaluate its pH and osmolality. EE solutes composition was concluded following Daly and Jones (2017), Minamikawa and Morisawa (1996), Robertson (1989), and Yancey (2015).…”

Section: Media Compositionmentioning

confidence: 99%

Development of Sperm Cryopreservation Protocols for Sharks and Rays: New Tools for Elasmobranch Conservation

2021

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Elasmobranchs are one of the most endangered vertebrate groups on the planet, but despite this situation the use of reproductive techniques in elasmobranch conservation strategies has been scarce. Among these techniques, sperm preservation is a potential tool for ex situ conservation and aquaria sustainability. However, there are no widespread preservation protocols for elasmobranch sperm, and shark sperm cryopreservation has never been achieved before. Here we present the establishment of successful cryopreservation protocols for elasmobranch sperm, tested in several species. We have formulated a sperm extender that can be used for different elasmobranch species, capable of maintaining sperm motility for several weeks. Additionally, we achieved the cryopreservation of sperm by previously diluting it in our extender and supplementing it with different combinations of cryoprotectants. The effects of methanol and dimethyl sulfoxide as permeating cryoprotectants were evaluated, as well egg yolk as a non-permeating cryoprotectant. Sperm quality was assessed by studying the motility and membrane integrity post-thawing, demonstrating its effectiveness in the 10 species tested, including two which are considered Critically Endangered. This is the first time that shark sperm cryopreservation has been reported, broadening our knowledge of the reproductive techniques that can be applied to elasmobranchs and laying the foundations for the first cryobanks for shark and ray sperm. Outcomes from this study will be useful for ex situ conservation efforts developed by public aquaria. A regular supply of frozen sperm will reduce the problems that result from the transport of specimens, inbreeding or lack of synchronized reproductive cycles in captivity.

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“…83,84 Consequently, cartilaginous fishes differ the least among fish from the prototype model of jawed vertebrate gas transport. While their plasma Na + and Clconcentrations are much lower than seawater values, their plasma is isosmotic with their seawater environment because of the high plasma urea concentrations, typically up to 0.5 M. 85 Urea at these levels usually denatures proteins, but urea concentrations even up to 5 M appear to have minimal effects on Hb-O 2 transport function. First, the plasma osmolality of marine elasmobranchs is about three to fourfold higher than almost all other vertebrates.…”

Section: The Elasmobranchsmentioning

confidence: 99%

“…First, the plasma osmolality of marine elasmobranchs is about three to fourfold higher than almost all other vertebrates. While their plasma Na + and Clconcentrations are much lower than seawater values, their plasma is isosmotic with their seawater environment because of the high plasma urea concentrations, typically up to 0.5 M. 85 Urea at these levels usually denatures proteins, but urea concentrations even up to 5 M appear to have minimal effects on Hb-O 2 transport function. 86 Although it appears that in most cartilaginous fishes urea has a minimal effect on Hb function, 80,86 there are exceptions.…”

Section: The Elasmobranchsmentioning

confidence: 99%

Regulation of erythrocyte function: Multiple evolutionary solutions for respiratory gas transport and its regulation in fish

2019

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Gas transport concepts in vertebrates have naturally been formulated based on human blood. However, the first vertebrates were aquatic, and fish and tetrapods diverged hundreds of millions years ago. Water-breathing vertebrates live in an environment with low and variable O 2 levels, making environmental O 2 an important evolutionary selection pressure in fishes, and various features of their gas transport differ from humans. Erythrocyte function in fish is of current interest, because current environmental changes affect gas transport, and because especially zebrafish is used as a model in biomedical studies, making it important to understand the differences in gas transport between fish and mammals to be able to carry out meaningful studies. Of the close to thirty thousand fish species, teleosts are the most species-numerous group.However, two additional radiations are discussed: agnathans and elasmobranchs.The gas transport by elasmobranchs may be closest to the ancestors of tetrapods. The major difference in their haemoglobin (Hb) function to humans is their high urea tolerance. Agnathans differ from other vertebrates by having Hbs, where cooperativity is achieved by monomer-oligomer equilibria. Their erythrocytes also lack the anion exchange pathway with profound effects on CO 2 transport. Teleosts are characterized by highly pH sensitive Hbs, which can fail to become fully O 2 -saturated at low pH. An adrenergically stimulated Na + /H + exchanger has evolved in their erythrocyte membrane, and plasma-accessible carbonic anhydrase can be differentially distributed among their tissues. Together, and differing from other vertebrates, these features can maximize O 2 unloading in muscle while ensuring O 2 loading in gills. K E Y W O R D Sadrenergically stimulated Na + /H + exchange, anion exchange, Bohr effect, carbonic anhydrase, erythrocyte, oxygen equilibrium curve (OEC), Root effect 2 of 16 | NIKINMAA et Al.3 40 ) stabilize the T-state (these so-called allosteric effectors bind to sites other than the O 2 binding site). The overall OEC of Hb molecules is determined by the probabilities of T-or R-state occurrence; the equilibrium between T-and R-states is virtually instantaneous.F I G U R E 4 O 2 equilibrium curves of rainbow trout (A) at resting plasma pH (7.65) and (B) at pH 7.40, where the Root effect has been induced (ie, O 2 saturation approaches asymptotically a value below full saturation, in this case maximal O 2 saturation is 69%, ie, Root effect 31%; data from 98 )

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Organic Osmolytes in Elasmobranchs

Cited by 12 publications

References 178 publications

High concentrations of trimethylamines in slime glands inhibit skein unraveling in Pacific hagfish

High concentrations of trimethylamines in slime glands inhibit skein unraveling in Pacific hagfish

Development of Sperm Cryopreservation Protocols for Sharks and Rays: New Tools for Elasmobranch Conservation

Regulation of erythrocyte function: Multiple evolutionary solutions for respiratory gas transport and its regulation in fish

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