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Andrew J Gillis - One of the best experts on this subject based on the ideXlab platform.
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conserved and unique transcriptional features of pharyngeal arches in the skate Leucoraja erinacea and evolution of the jaw
bioRxiv, 2021Co-Authors: Christine Hirschberger, Katharine E Criswell, Victoria A Sleight, Stephen J Clark, Andrew J GillisAbstract:The origin of the jaw is a long-standing problem in vertebrate evolutionary biology. Classical hypotheses of serial homology propose that the upper and lower jaw evolved through modifications of dorsal and ventral gill arch skeletal elements, respectively. If the jaw and gill arches are derived members of a primitive branchial series, we predict that they would share common developmental patterning mechanisms. Using candidate and RNAseq/differential gene expression analyses, we find broad conservation of dorsoventral patterning mechanisms within the developing mandibular, hyoid and gill arches of a cartilaginous fish, the skate (Leucoraja erinacea). Shared features include expression of genes encoding members of the ventralising BMP and endothelin signalling pathways and their effectors, the joint markers bapx1 and gdf5 and pro-chondrogenic transcription factors barx1 and gsc, and the dorsalising transcription factor pou3f3. Additionally, we find that mesenchymal expression of eya1/six1 is an ancestral feature of the mandibular arch of jawed vertebrates, while differences in notch signalling distinguish the mandibular and gill arches in skate. Comparative transcriptomic analyses of mandibular and gill arch tissues reveal additional genes differentially expressed along the dorsoventral axis of the pharyngeal arches, including scamp5 as a novel marker of the dorsal mandibular arch, as well as distinct transcriptional features of mandibular and gill arch muscle progenitors and developing gill buds. Taken together, our findings reveal conserved patterning mechanisms in the pharyngeal arches of jawed vertebrates, consistent with serial homology of their skeletal derivatives, as well as unique transcriptional features that may underpin distinct jaw and gill arch morphologies.
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embryonic origin and serial homology of gill arches and paired fins in the skate Leucoraja erinacea
eLife, 2020Co-Authors: Andrew J Gillis, Victoria A SleightAbstract:A common way to evolve new body parts is to copy existing ones and to remodel them. In insects for example, the antennae, mouth parts and legs all follow the same basic body plan, with modifications that adapt them for different uses. In the late 19th century, anatomist Karl Gegenbaur noticed a similar pattern in fish. He saw similarities between pairs of fins and pairs of gills, suggesting that one evolved from the other. But there is currently no fossil evidence documenting such a transformation. Modern research has shown that the development of both gill and fin skeletons shares common genetic pathways. But the cells that form the two structures do not come from the same place. Gill skeletons develop from a part of the embryo called the neural crest, while fin skeletons come from a region called the mesoderm. One way to test Gegenbaur’s idea is to look more closely at the cells that form gill and fin skeletons as fish embryos develop. Here, Sleight and Gillis examined the gills and fins of a cartilaginous fish called Leucoraja erinacea, also known as the little skate. Sleight and Gillis labelled the cells from the neural crest and mesoderm of little skate embryos with a fluorescent dye and then tracked the cells over several weeks. While the fins did form from mesoderm cells, the gills did not develop as expected. The first gill contained only neural crest cells, but the rest were a mixture of both cell types. This suggests that fins and gills develop from a common pool of cells that consists of both neural crest and mesoderm cells, which have the potential to develop into either body part. This previously unrecognised embryonic continuity between gills and fins explains why these structures respond in the same way to the same genetic cues, regardless of what cell type they develop from. Based on this new evidence, Sleight and Gillis believe that Gegenbaur was right, and that fins and gills do indeed share an evolutionary history. While firm evidence for the transformation of gills into fins remains elusive, this work suggests it is possible. A deeper understanding of the process could shed light on the development of other repeated structures in nature. Research shows that animals use a relatively small number of genetic cues to set out their body plans. This can make it hard to use genetics alone to study their evolutionary history. But, looking at how different cell types respond to those cues to build anatomical features, like fins and gills, could help to fill in the gaps.
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embryonic origin and serial homology of gill arches and paired fins in the skate Leucoraja erinacea
bioRxiv, 2020Co-Authors: Victoria A Sleight, Andrew J GillisAbstract:Paired fins are a defining feature of the jawed vertebrate body plan, but their evolutionary origin remains unresolved. Gegenbaur proposed that paired fins evolved as gill arch serial homologues, but this hypothesis is now widely discounted, owing largely to the presumed distinct embryonic origins of these structures from mesoderm and neural crest, respectively. Here, we use cell lineage tracing to test the embryonic origin of the pharyngeal and paired fin skeleton in the skate (Leucoraja erinacea). We find that while the jaw and hyoid arch skeleton derive from neural crest, and the pectoral fin skeleton from mesoderm, the gill arches are of dual origin, receiving contributions from both germ layers. We propose that gill arches and paired fins are serially homologous as derivatives of a continuous, dual-origin mesenchyme with common skeletogenic competence, and that this serial homology accounts for their parallel anatomical organization and shared responses to axial patterning signals.Competing Interest StatementThe authors have declared no competing interest.View Full Text
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adult chondrogenesis and spontaneous cartilage repair in the skate Leucoraja erinacea
eLife, 2020Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:For our joints to move around freely, they are lubricated with cartilage. In growing mammals, this tissue is continuously made by the body. But, by adulthood, this cartilage will have been almost entirely replaced by bone. It is also difficult for adult bodies to replenish what cartilage does remain – such as that in the joints. When growing new cartilage, the body uses so-called progenitor cells, which have the ability to turn into different cell types. Progenitor cells are recruited to the joints, where they transform into cartilage cells called chondrocytes, which generate new cartilage. But adults lack these progenitor cells, leaving them unfit to heal damaged cartilage after injury or diseases like osteoarthritis. In contrast, certain groups of fishes, such as skates, sharks and rays, produce cartilage throughout their life — indeed their whole skeleton is made of cartilage. So, what is the difference between these cartilaginous fishes and mammals? Why can they generate cartilage throughout their lives, while humans are unable to? And does this mean that these adult fish are better at healing injured cartilage? Marconi et al. used skates (Leucoraja erinacea) to study how cartilage develops, grows and heals in a cartilaginous fish. Progenitor cells were found in a layer that wraps around the cartilage skeleton (called the perichondrium). These cells were also shown to activate genes that control cartilage development. By labelling these progenitor cells, their presence and movements could be tracked around the fish. Marconi et al. found progenitor cells in adult skates that were able to generate chondrocytes. Skates were also shown to spontaneously repair damaged cartilage in experiments where cartilage was injured. Marconi et al. have identified the skate as a new animal model for studying cartilage growth and repair. Studying the mechanisms that skate progenitor cells use for generating cartilage could lead to improvements in current therapies used for repairing cartilage in the joints.
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adult chondrogenesis and spontaneous cartilage repair in the skate Leucoraja erinacea
bioRxiv, 2019Co-Authors: Aleksandra Marconi, Andrew J Gillis, Amy HancockronemusAbstract:Mammalian articular cartilage is an avascular tissue with poor capacity for spontaneous repair. Here, we show that embryonic development of cartilage in the skate (Leucoraja erinacea) mirrors that of mammals, with developing chondrocytes co-expressing genes encoding the transcription factors Sox5, Sox6 and Sox9. However, in skate, transcriptional features of developing cartilage persist into adulthood, both in peripheral chondrocytes and in cells of the fibrous perichondrium that ensheaths the skeleton. Using pulse-chase label retention experiments and multiplexed in situ hybridization, we identify a population of cycling Sox5/6/9+ perichondral progenitor cells that generate new cartilage during adult growth, and we show that persistence of chondrogenesis in adult skates correlates with ability to spontaneously repair cartilage injuries. Skates therefore offer a unique model for adult chondrogenesis and cartilage repair and may serve as inspiration for novel cell-based therapies for skeletal pathologies, such as osteoarthritis.
James A Sulikowski - One of the best experts on this subject based on the ideXlab platform.
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Assessing reproductive status in elasmobranch fishes using steroid hormones extracted from skeletal muscle tissue
Conservation Physiology, 2013Co-Authors: Bianca K. Prohaska, Carolyn R. Wheeler, A. Christine Brown, William B Driggers, Eric R Hoffmayer, Paul C. W. Tsang, James A SulikowskiAbstract:Elasmobranch fishes (sharks, skates, and rays) are particularly susceptible to anthropogenic threats, making a thorough understanding of their life history characteristics essential for proper management. Historically, elasmobranch reproductive data have been collected by lethal sampling, an approach that is problematic for threatened and endangered species. However, recent studies have demonstrated that non-lethal approaches can be as effective as lethal ones for assessment of the reproductive status of an animal. For example, plasma has been used to examine concentrations of steroid hormones. Additionally, skeletal muscle tissue, which can be obtained non-lethally and with minimal stress, can also be used to quantify concentrations of steroid hormones. Skeletal muscle progesterone, testosterone, and estradiol concentrations were determined to be statistically significant indicators of reproductive status in the oviparous Leucoraja erinacea, the yolk-dependent viviparous Squalus acanthias, and the yolk-sac placental viviparous Rhizoprionodon terraenovae. The results of the present study demonstrate that steroid hormones present in non-lethally harvested skeletal muscle tissue can be used as reliable indicators of reproductive status in elasmobranchs.
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using estradiol and progesterone concentrations to assess individual variability in the reproductive cyclicity of captive female little skates Leucoraja erinacea from the western gulf of maine
Fish Physiology and Biochemistry, 2013Co-Authors: Laura Jay Williams, Matthew D. Campbell, Paul C. W. Tsang, James A SulikowskiAbstract:In the current study, plasma steroid hormones were used to assess the individual variability of Leucoraja erinacea over the course of 12 months, in hopes of further defining its reproductive cycle. No statistical differences in hormone concentrations were observed between the isolated and non-isolated female skates. Monthly E2 concentrations ranged from 1,430 pg ml−1 in August to 3,940 pg ml−1 in March, indicating the presence of mature ovarian follicles and supporting the conclusions from previous studies that L. erinacea is capable of reproducing year-round. Concentrations of E2 were significantly elevated or depressed during some months (February, March, June, July, August, and September) of the year, suggesting that reproductive activity may vary over the annual cycle. Even though monthly P4 concentrations were highly variable, ranging from 82 pg ml−1 in November to 816 pg ml−1 in September, no significant reproductive peaks were observed. In addition, a persistently large variation in E2 and P4 concentrations, indicative of reproductive asynchrony within (mean CV 62 % and CV 69 %, respectively) and between (mean range CV 78 and 125 %, respectively) individual skates, was observed throughout the study. Collectively, the continually high E2 concentrations and variability in both hormones observed in the current study are indicative of an oviparous species that reproduces actively throughout the year. However, the weekly sampling frequency revealed that plasma E2 concentrations, not P4, were more useful to assess reproductive status in asynchronous continuously breeding oviparous elasmobranchs.
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seasonal variations in the physiological stress response to discrete bouts of aerial exposure in the little skate Leucoraja erinacea
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2012Co-Authors: A M Cicia, James A Sulikowski, Lela S Schlenker, John W MandelmanAbstract:Abstract Aerial exposure and acute thermal stress have been shown to elicit profound physiological disruptions in obligate water-breathing teleosts. However, no study has investigated these responses in an elasmobranch. To address this, venous blood samples were collected and evaluated from little skates (Leucoraja erinacea) subjected to discrete aerial exposure durations (0, 15, and 50 min) coupled with differing abrupt thermal changes (gradient between seawater and air; winter: ΔT = − 3 °C; summer: ΔT = + 9 °C) in two distinct laboratory studies. In general, blood acid–base properties (e.g. decline in pH; elevation in PCO2) and select metabolites (elevated whole-blood lactate) and electrolytes (elevated plasma K+) were significantly disrupted by aerial exposure, and were most disturbed after skates were exposed to air for 50 min. However, the magnitude of the blood acid–base perturbations, metabolic contribution to the resulting blood acidosis, elevations to ionic and metabolic parameters, and delayed mortality were more extreme during the summer study, suggesting that acute thermal stress exacerbates the physiological impairments associated with aerial exposure in little skates. Conversely, a reduced thermal gradient (from seawater to air) may attenuate the magnitude of metabolic and ionic perturbations, resulting in a high physiological threshold for coping with extended aerial exposure.
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seasonal variation in fecundity egg case viability gestation and neonate size for little skates Leucoraja erinacea in the gulf of maine
Environmental Biology of Fishes, 2011Co-Authors: Brittany D Palm, David M Koester, William B Driggers, James A SulikowskiAbstract:Landings of the little skate, Leucoraja erinacea, within the territorial waters of the United States are currently regulated by a federal fishery management plan (FMP). For a FMP to be effective, thorough knowledge of a species’ reproductive biology is essential. Currently, little information exists on annual fecundity, egg case viability, gestation length, and neonate total length, for the little skate in the Gulf of Maine. To study these reproductive parameters, mature skates and egg cases were housed in fiberglass tanks with an open seawater system that provided natural, seasonal fluctuations in water temperature. Egg case deposition was highest during summer months with a seasonal peak in June. Of the 324 egg cases laid by seven females (c. 46 eggs per year, per female), 74.1% were viable. Gestation lengths ranged from 22 to 54 weeks throughout the four seasons. Egg cases laid in the fall had the longest gestation times (44.9 weeks, ± 0.13 weeks) and those laid in the spring had the shortest gestation times (24.5 weeks, ± 0.21 weeks). Total lengths of neonates from spring oviposition were statistically the longest (10.74 ± 0.05 cm) when compared to neonates from other seasons; however, egg viability was statistically the lowest for spring when compared seasonally.
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size and age estimates at sexual maturity for the little skate Leucoraja erinacea from the western gulf of maine u s a
Journal of Fish Biology, 2009Co-Authors: A M Cicia, G W Ingram, David M Koester, Jeff Kneebone, William B Driggers, Paul C. W. Tsang, James A SulikowskiAbstract:Size and age estimates at sexual maturity were determined for 162 male and 273 female little skates Leucoraja erinacea collected from the western Gulf of Maine. Maturity ogives suggest that 50% maturity in females occurs at age 9·5 years and 480 mm total length (LT), whereas 50% maturity in males occurs at a slightly younger age of 7·7 years and smaller size of 460 mm LT. Age estimates were made from 389 L. erinacea ranging in size from 93 to 570 mm LT. The index of average per cent error and age-bias plots indicated that the ageing methods were precise and non-biased. Additionally, annual periodicity of band formation was validated with oxytetracycline in eight individuals (three males and five females) ranging in age from 3 to 12 years. In conclusion, results from this study indicate that L. erinacea exhibits characteristics that make other elasmobranch populations highly susceptible to overexploitation.
Bram V. Lutton - One of the best experts on this subject based on the ideXlab platform.
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A role for the CXCR4-CXCL12 axis in the little skate, Leucoraja erinacea.
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2018Co-Authors: Taylor A. Hersh, Alexandria L. Dimond, Brittany A. Ruth, Noah V. Lupica, Jacob C. Bruce, John M Kelley, Benjamin L King, Bram V. LuttonAbstract:The interaction between C-X-C chemokine receptor type 4 (CXCR4) and its cognate ligand, C-X-C motif chemokine ligand 12 (CXCL12), plays a critical role in regulating hematopoietic stem cell activation and subsequent cellular mobilization. Extensive studies of these genes have been conducted in mammals, but much less is known about the expression and function of CXCR4 and CXCL12 in non-mammalian vertebrates. In the present study, we identify simultaneous expression of CXCR4 and CXCL12 orthologues in the epigonal organ (the primary hematopoietic tissue) of the little skate, Leucoraja erinacea. Genetic and phylogenetic analyses were functionally supported by significant mobilization of leukocytes following administration of Plerixafor: a CXCR4 antagonist and clinically important drug. Our results provide evidence that, as in humans, Plerixafor disrupts CXCR4/CXCL12 binding in the little skate, facilitating release of leukocytes into the bloodstream. Our study illustrates the value of the little skate as a mo...
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morphological relationships and leukocyte influence on steroid production in the epigonal organ ovary complex of the skate Leucoraja erinacea
Journal of Morphology, 2008Co-Authors: Bram V. Lutton, Ian P CallardAbstract:In elasmobranchs, a unique association exists between an immune tissue, the epigonal organ (EO), and the gonads. In this study, the histological and vascular relationships of the EO and ovarian follicles of the little skate, Leucoraja erinacea, were assessed. Perfusions of Evans blue dye and Batson's monomer showed a shared vascular pathway from the gonadal artery into the epigonal-ovary complex, with blood first entering the EO and then perfusing the ovarian follicles. Histological studies demonstrated direct cellular contact between epigonal leukocytes and the follicle wall (FW), as well as the presence of leukocytes between the steroidogenic theca and granulosa cells. In vitro analyses demonstrated that epigonal cells co-cultured with FW cells cause a dose-dependent inhibition of estrogen (E2) and testosterone (T) production. In contrast, conditioned media from epigonal leukocytes, stimulated or unstimulated with lipopolysaccharide (10 μg/ml), increase the production of E2 and T from FW cells of the ovaries. These studies provide a basis for further investigations of leukocyte secreted factors and cell contact modulation of follicular steroid production. J Morphol., 2008. © 2008 Wiley-Liss, Inc.
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Morphological relationships and leukocyte influence on steroid production in the epigonal organ-ovary complex of the skate, Leucoraja erinacea.
Journal of morphology, 2008Co-Authors: Bram V. Lutton, Ian P CallardAbstract:In elasmobranchs, a unique association exists between an immune tissue, the epigonal organ (EO), and the gonads. In this study, the histological and vascular relationships of the EO and ovarian follicles of the little skate, Leucoraja erinacea, were assessed. Perfusions of Evans blue dye and Batson's monomer showed a shared vascular pathway from the gonadal artery into the epigonal-ovary complex, with blood first entering the EO and then perfusing the ovarian follicles. Histological studies demonstrated direct cellular contact between epigonal leukocytes and the follicle wall (FW), as well as the presence of leukocytes between the steroidogenic theca and granulosa cells. In vitro analyses demonstrated that epigonal cells co-cultured with FW cells cause a dose-dependent inhibition of estrogen (E2) and testosterone (T) production. In contrast, conditioned media from epigonal leukocytes, stimulated or unstimulated with lipopolysaccharide (10 μg/ml), increase the production of E2 and T from FW cells of the ovaries. These studies provide a basis for further investigations of leukocyte secreted factors and cell contact modulation of follicular steroid production. J Morphol., 2008. © 2008 Wiley-Liss, Inc.
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influence of reproductive activity sex steroids and seasonality on epigonal organ cellular proliferation in the skate Leucoraja erinacea
General and Comparative Endocrinology, 2008Co-Authors: Bram V. Lutton, Ian P CallardAbstract:Abstract In elasmobranchs, the epigonal organ, a unique leukopoietic immune tissue, is associated with the gonads. As the ovaries increase in size during reproductive activity, the overall mass of the epigonal organ does not change. However, immunohistochemistry (proliferating cell nuclear antigen Ab) demonstrated more proliferative activity and extravasation of epigonal leukocytes from blood vessels in reproductively active (RA) skates ( Leucoraja erinacea ) than in non-reproductively active (NRA) skates. In addition, [ 3 H]thymidine incorporation was greater in epigonal leukocytes from RA skates than in leukocytes from NRA skates. Plasma from RA skates, but not from NRA skates, increased proliferation of epigonal leukocytes in vitro , an effect that was not seen using steroid-free plasma. In contrast to the stimulatory effect of plasma on leukocyte proliferation, addition of steroids (estrogen, progesterone, testosterone, and dexamethasone) in vitro decreased [ 3 H]thymidine incorporation. While the inhibitory response to steroids was seasonally variable, 3 [H]thymidine incorporation was always highest in RA animals, in which plasma steroid levels were also consistently highest. These studies suggest functional interactions between reproductive and immune tissues in the skate, and that cellular turnover in epigonal tissue may be influenced by gonadal activity.
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effects of reproductive activity and sex hormones on apoptosis in the epigonal organ of the skate Leucoraja erinacea
General and Comparative Endocrinology, 2007Co-Authors: Bram V. LuttonAbstract:In elasmobranchs, a unique association exists between an immune tissue, the epigonal organ, and the gonads. The intimate morphological relationship between these tissues suggests functional interactions. In this study, we used apoptosis to assess differences between epigonal tissues of reproductively active (RA) and non-reproductively active (NRA) skates (Leucoraja erinacea). Plasma steroid levels were significantly higher in RA than in NRA animals, and TUNEL analysis showed that epigonal tissue of RA skates had greater DNA fragmentation than NRA skates. Addition of steroids to epigonal leukocytes in vitro demonstrated that progesterone, testosterone, and dexamethasone, but not estrogen, induced apoptosis of epigonal leukocytes as evidenced by DNA laddering and caspase-3 antibody labeling. This study supports recent evidence that cellular homeostasis of epigonal lymphomyeloid tissue may be influenced by gonadal activity and reproductive steroids in a representative of the most basal gnathastome group.
Nazzareno Ballatori - One of the best experts on this subject based on the ideXlab platform.
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Organic Solute Transporter, OSTα-OSTβ: Its Role In Bile Acid Transport and Cholestasis
Seminars in liver disease, 2010Co-Authors: Carol J. Soroka, Nazzareno Ballatori, James L. BoyerAbstract:Organic solute transporter α-beta (OSTα-OSTβ) is a unique heteromeric transporter localized to the basolateral membrane of epithelial cells involved in sterol transport. It is believed to be the primary bile acid efflux transporter in the intestine of mammals and is therefore essential to bile acid homeostasis and the enterohepatic circulation. First described in the evolutionarily primitive small skate, Leucoraja erinacea, this facilitated transporter requires expression of both subunits for its function. It can transport a variety of bile acids, as well as estrone 3-sulfate, dehydroepiandrosterone 3-sulfate, digoxin and prostaglandin E2. Expression of both subunits is variable between species and tissues; in humans high expression is noted in the liver, small intestine, kidney, testis, and adrenal gland. OSTα-OSTβ is directly regulated by the bile acid sensing nuclear receptor, farnesoid X receptor (FXR). Furthermore, it is part of the complex regulatory pathway that controls bile acid synthesis and homeostasis. Hepatic OSTα-OSTβ is up-regulated in cholestasis in both humans and rodents, where it appears to play a protective role. Additional studies are necessary to determine its role in liver injury, bile acid malabsorption, and lipid and glucose metabolism, as well as a potential protective role for kidney OSTα-OSTβ in cholestasis.
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hepatic uptake and biliary excretion of manganese in the little skate Leucoraja erinacea
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2009Co-Authors: Michael S. Madejczyk, Nazzareno Ballatori, James L. BoyerAbstract:The liver is a major organ involved in regulating whole body manganese (Mn) homeostasis; however, the mechanisms of Mn transport across the hepatocyte basolateral and canalicular membranes remain poorly defined. To gain insight into these transport steps, the present study measured hepatic uptake and biliary excretion of Mn in an evolutionarily primitive marine vertebrate, the elasmobranch Leucoraja erinacea, the little skate. Mn was rapidly removed from the recirculating perfusate of isolated perfused skate livers in a dose-dependent fashion; however, only a small fraction was released into bile (<2% in 7h). Mn was also rapidly taken up by freshly isolated skate hepatocytes in culture. Mn uptake was inhibited by a variety of divalent metals, but not by cesium. Analysis of the concentration-dependence of Mn uptake revealed of two components, with apparent Km values 1.1 ± 0.1 μM and 112 ± 29 μM. The Km value for the high-affinity component was similar to the measured skate blood Mn concentration, 1.9 ± 0.5 μM. Mn uptake was reduced by nearly half when bicarbonate was removed from the culture medium, but was unaffected by a change in pH from 6.5 to 8.5, or by substitution of Na with Li or K. Mn efflux from the hepatocytes was also rapid, and was inhibited when cells were treated with 0.5 mM 2,4-dinitrophenol to deplete ATP levels. These data indicate that skate liver has efficient mechanisms for removing Mn from the sinusoidal circulation, whereas overall biliary excretion is low and appears to be mediated in part by an ATP-sensitive mechanism.
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Hepatic uptake and biliary excretion of manganese in the little skate, Leucoraja erinacea.
Comparative Biochemistry and Physiology C-toxicology & Pharmacology, 2008Co-Authors: Michael S. Madejczyk, James L. Boyer, Nazzareno BallatoriAbstract:The liver is a major organ involved in regulating whole body manganese (Mn) homeostasis; however, the mechanisms of Mn transport across the hepatocyte basolateral and canalicular membranes remain poorly defined. To gain insight into these transport steps, the present study measured hepatic uptake and biliary excretion of Mn in an evolutionarily primitive marine vertebrate, the elasmobranch Leucoraja erinacea, the little skate. Mn was rapidly removed from the recirculating perfusate of isolated perfused skate livers in a dose-dependent fashion; however, only a small fraction was released into bile (
Bianca K. Prohaska - One of the best experts on this subject based on the ideXlab platform.
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Assessing reproductive status in elasmobranch fishes using steroid hormones extracted from skeletal muscle tissue
Conservation Physiology, 2013Co-Authors: Bianca K. Prohaska, Carolyn R. Wheeler, A. Christine Brown, William B Driggers, Eric R Hoffmayer, Paul C. W. Tsang, James A SulikowskiAbstract:Elasmobranch fishes (sharks, skates, and rays) are particularly susceptible to anthropogenic threats, making a thorough understanding of their life history characteristics essential for proper management. Historically, elasmobranch reproductive data have been collected by lethal sampling, an approach that is problematic for threatened and endangered species. However, recent studies have demonstrated that non-lethal approaches can be as effective as lethal ones for assessment of the reproductive status of an animal. For example, plasma has been used to examine concentrations of steroid hormones. Additionally, skeletal muscle tissue, which can be obtained non-lethally and with minimal stress, can also be used to quantify concentrations of steroid hormones. Skeletal muscle progesterone, testosterone, and estradiol concentrations were determined to be statistically significant indicators of reproductive status in the oviparous Leucoraja erinacea, the yolk-dependent viviparous Squalus acanthias, and the yolk-sac placental viviparous Rhizoprionodon terraenovae. The results of the present study demonstrate that steroid hormones present in non-lethally harvested skeletal muscle tissue can be used as reliable indicators of reproductive status in elasmobranchs.