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https://www.readbyqxmd.com/read/28214875/a-developmental-study-of-the-cerebellar-nucleus-in-the-catshark-a-basal-gnathostome
#1
Sol Pose-Méndez, Isabel Rodríguez-Moldes, Eva Candal, Sylvie Mazan, Ramón Anadón
The output of the cerebellar cortex is mainly released via cerebellar nuclei which vary in number and complexity among gnathostomes, extant vertebrates with a cerebellum. Cartilaginous fishes, a basal gnathostome lineage, show a conspicuous, well-organized cerebellar nucleus, unlike ray-finned fishes. To gain insight into the evolution and development of the cerebellar nucleus, we analyzed in the shark Scyliorhinus canicula (a chondrichthyan model species) the developmental expression of several genes coding for transcription factors (ScLhx5,ScLhx9,ScTbr1, and ScEn2) and the distribution of the protein calbindin, since all appear to be involved in cerebellar nuclei patterning in other gnathostomes...
February 18, 2017: Brain, Behavior and Evolution
https://www.readbyqxmd.com/read/28159401/relationships-of-mercury-concentrations-across-tissue-types-muscle-regions-and-fins-for-two-shark-species
#2
Jason R O'Bryhim, Douglas H Adams, Julia L Y Spaet, Gary Mills, Stacey L Lance
Mercury (Hg) exposure poses a threat to both fish and human health. Sharks are known to bioaccumulate Hg, however, little is known regarding how Hg is distributed between different tissue groups (e.g. muscle regions, organs). Here we evaluated total mercury (THg) concentrations from eight muscle regions, four fins (first dorsal, left and right pectorals, caudal-from both the inner core and trailing margin of each fin), and five internal organs (liver, kidney, spleen, heart, epigonal organ) from two different shark species, bonnethead (Sphyrna tiburo) and silky shark (Carcharhinus falciformis) to determine the relationships of THg concentrations between and within tissue groups...
January 31, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28116055/the-development-of-an-intermediate-duration-tag-to-characterize-the-diving-behavior-of-large-whales
#3
Bruce R Mate, Ladd M Irvine, Daniel M Palacios
The development of high-resolution archival tag technologies has revolutionized our understanding of diving behavior in marine taxa such as sharks, turtles, and seals during their wide-ranging movements. However, similar applications for large whales have lagged behind due to the difficulty of keeping tags on the animals for extended periods of time. Here, we present a novel configuration of a transdermally attached biologging device called the Advanced Dive Behavior (ADB) tag. The ADB tag contains sensors that record hydrostatic pressure, three-axis accelerometers, magnetometers, water temperature, and light level, all sampled at 1 Hz...
January 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28089553/plastic-debris-straps-on-threatened-blue-shark-prionace-glauca
#4
Ana I Colmenero, Claudio Barría, Elisabetta Broglio, Salvador García-Barcelona
Juveniles of blue shark Prionace glauca caught in pelagic longlines targeting tuna and swordfish in the Atlantic Ocean and the Mediterranean Sea were found entangled with plastic straps around their gill region. The plastic debris were identified as strapping bands and caused several degrees of injuries on the dorsal musculature and pectoral fins. They were also obstructing the gill slits probably causing breathing issues. These records were uploaded in the web site seawatchers.org, and highlight the potential of citizen science in revealing the occurrence of such problems which could help to measure the effects of plastic debris on marine life...
January 12, 2017: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/28071651/marine-origin-of-retroviruses-in-the-early-palaeozoic-era
#5
Pakorn Aiewsakun, Aris Katzourakis
Very little is known about the ancient origin of retroviruses, but owing to the discovery of their ancient endogenous viral counterparts, their early history is beginning to unfold. Here we report 36 lineages of basal amphibian and fish foamy-like endogenous retroviruses (FLERVs). Phylogenetic analyses reveal that ray-finned fish FLERVs exhibit an overall co-speciation pattern with their hosts, while amphibian FLERVs might not. We also observe several possible ancient viral cross-class transmissions, involving lobe-finned fish, shark and frog FLERVs...
January 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/27988590/-i-pseudotrichonotus-i-i-belos-i-new-species-first-record-of-the-fish-family-pseudotrichonotidae-from-australia-teleostei-aulopiformes
#6
Anthony C Gill, John J Pogonoski
Pseudotrichonotus belos new species, described from three specimens trawled in 100-120 m offshore between Exmouth Gulf and Shark Bay, Western Australia, represents the first record of the sand-diving fish family Pseudotrichonotidae from Australian waters. It differs from its two congeners in having a more posteriorly positioned dorsal fin (predorsal length 39.6-41.2 % SL) and fewer dorsal- and anal-fin rays (31-33 and 12, respectively).
December 5, 2016: Zootaxa
https://www.readbyqxmd.com/read/27987932/by-products-of-scyliorhinus-canicula-prionace-glauca-and-raja-clavata-a-valuable-source-of-predominantly-6s-sulfated-chondroitin-sulfate
#7
Ramon Novoa-Carballal, Ricardo Pérez-Martín, María Blanco, Carmen G Sotelo, Dario Fassini, Cláudia Nunes, Manuel A Coimbra, Tiago H Silva, Rui L Reis, José Antonio Vázquez
Chondroitin sulfate (CS) was isolated from Scyliorhinus canicula (fin, head and skeleton), Prionace glauca (head), and Raja clavata (skeleton) by-products from fish processing industry using environmentally friendly processes. The molecular weight was determined by gel permeation chromatography and the sugar composition and sulfation position by NMR and SAX-HPLC after enzymatic digestion. The CSs showed a prevalent 6S GalNAc sulfation for the 3 species (4S/6S ratio lower than 1). A higher 6S sulfation was observed for P...
February 10, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/27853556/relations-between-morphology-buoyancy-and-energetics-of-requiem-sharks
#8
Gil Iosilevskii, Yannis P Papastamatiou
Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, girth and body temperature. Our analysis predicts an intricate relation between these parameters, suggesting that ectothermic species residing in cooler temperatures must either have longer pectoral fins and/or be more buoyant in order to maintain swimming performance...
October 2016: Royal Society Open Science
https://www.readbyqxmd.com/read/27794535/convergence-in-thunniform-anatomy-in-lamnid-sharks-and-jurassic-ichthyosaurs
#9
Theagarten Lingham-Soliar
Among extinct ichthyosaurs the Jurassic forms Ichthyosaurus and Stenopterygius share a number of anatomical specializations with lamnid sharks, characterized in the white shark, Carcharodon carcharias These features allow their inclusion within the mode of high-speed thunniform swimming to which only two other equally distinctive phylogenetic groups belong, tuna and dolphins-a striking testaments to evolutionary convergence. Jurassic ichthyosaurs evolved from reptiles that had returned to the sea (secondarily adapted) about 250 million years ago (MYA) while lamnid sharks evolved about 50 MYA from early cartilaginous fishes (originating ca...
December 2016: Integrative and Comparative Biology
https://www.readbyqxmd.com/read/27783634/whale-shark-rhincodon-typus-seasonal-occurrence-abundance-and-demographic-structure-in-the-mid-equatorial-atlantic-ocean
#10
Bruno C L Macena, Fábio H V Hazin
Whale sharks are generally associated with environmental factors that drive their movements to specific locations where food availability is high. Consequently, foraging is believed to be the main reason for the formation of whale shark aggregations. Feeding aggregations occur mainly in nearshore areas and are composed primarily of immature individuals. Conversely, aggregations of mature adults are rarely observed, and their occurrence is correlated with oceanic environments. Despite an increase in the number of whale shark studies, information on mating and parturition grounds is still lacking...
2016: PloS One
https://www.readbyqxmd.com/read/27774596/a-novel-field-method-to-distinguish-between-cryptic-carcharhinid-sharks-australian-blacktip-shark-carcharhinus-tilstoni-and-common-blacktip-shark-c-limbatus-despite-the-presence-of-hybrids
#11
G J Johnson, R C Buckworth, H Lee, J A T Morgan, J R Ovenden, C R McMahon
Multivariate and machine-learning methods were used to develop field identification techniques for two species of cryptic blacktip shark. From 112 specimens, precaudal vertebrae (PCV) counts and molecular analysis identified 95 Australian blacktip sharks Carcharhinus tilstoni and 17 common blacktip sharks Carcharhinus limbatus. Molecular analysis also revealed 27 of the 112 were C. tilstoni × C. limbatus hybrids, of which 23 had C. tilstoni PCV counts and four had C. limbatus PCV counts. In the absence of further information about hybrid phenotypes, hybrids were assigned as either C...
January 2017: Journal of Fish Biology
https://www.readbyqxmd.com/read/27723102/dicephalous-v-diprosopus-sharks-record-of-a-two-headed-embryo-of-galeus-atlanticus-and-review-of-the-literature
#12
V Sans-Coma, C Rodríguez, M A López-Unzu, M Lorenzale, B Fernández, L Vida, A C Durán
As far as is known, this paper gives the first description of a two-headed shark embryo belonging to an oviparous species, Galeus atlanticus (Carcharhiniformes: Scyliorhinidae). The specimen was detected among 797 embryos intended for cardiovascular studies, which represents a defect incidence of 0·13%. Each head had a mouth, two eyes, a brain, a notochord and five gill openings on each side. The two heads fused behind the gills. On the single body, there were four anticipated dorsal fins, two anterior, right and left and two posterior, right and left...
January 2017: Journal of Fish Biology
https://www.readbyqxmd.com/read/27684706/shark-conservation-an-educational-approach-based-on-children-s-knowledge-and-perceptions-toward-sharks
#13
Kwok Ho Tsoi, Sau Ying Chan, Yeung Chung Lee, Brian Ho Yeung Ip, Chi Chiu Cheang
Shark conservation has become a focus of current international conservation efforts. However, the misunderstanding of sharks and their negative public portrayal may hinder their conservation. More importantly, the consumption of shark fin, which is very common in Chinese cultures, poses a significant threat to sharks. Hong Kong has long been the world's largest shark fin trading center. Shark conservation would become more sustainable if public understanding of this predatory fish and an appreciation of its ecological significance could be promoted...
2016: PloS One
https://www.readbyqxmd.com/read/27537913/cyanobacterial-neurotoxin-bmaa-and-mercury-in-sharks
#14
Neil Hammerschlag, David A Davis, Kiyo Mondo, Matthew S Seely, Susan J Murch, William Broc Glover, Timothy Divoll, David C Evers, Deborah C Mash
Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg), because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products...
2016: Toxins
https://www.readbyqxmd.com/read/27457414/great-hammerhead-sharks-swim-on-their-side-to-reduce-transport-costs
#15
Nicholas L Payne, Gil Iosilevskii, Adam Barnett, Chris Fischer, Rachel T Graham, Adrian C Gleiss, Yuuki Y Watanabe
Animals exhibit various physiological and behavioural strategies for minimizing travel costs. Fins of aquatic animals play key roles in efficient travel and, for sharks, the functions of dorsal and pectoral fins are considered well divided: the former assists propulsion and generates lateral hydrodynamic forces during turns and the latter generates vertical forces that offset sharks' negative buoyancy. Here we show that great hammerhead sharks drastically reconfigure the function of these structures, using an exaggerated dorsal fin to generate lift by swimming rolled on their side...
2016: Nature Communications
https://www.readbyqxmd.com/read/27339437/waves-traces-and-shark-fins
#16
Steven McVea, Kate Skehin, Mark Terris
No abstract text is available yet for this article.
June 23, 2016: Archives of Disease in Childhood. Education and Practice Edition
https://www.readbyqxmd.com/read/27291051/rethinking-trade-driven-extinction-risk-in-marine-and-terrestrial-megafauna
#17
Loren McClenachan, Andrew B Cooper, Nicholas K Dulvy
Large animals hunted for the high value of their parts (e.g., elephant ivory and shark fins) are at risk of extinction due to both intensive international trade pressure and intrinsic biological sensitivity. However, the relative role of trade, particularly in non-perishable products, and biological factors in driving extinction risk is not well understood [1-4]. Here we identify a taxonomically diverse group of >100 marine and terrestrial megafauna targeted for international luxury markets; estimate their value across three points of sale; test relationships among extinction risk, high value, and body size; and quantify the effects of two mitigating factors: poaching fines and geographic range size...
June 20, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27220775/seasonal-migration-of-the-starry-smooth-hound-shark-mustelus-asterias-as-revealed-from-tag-recapture-data-of-an-angler-led-tagging-programme
#18
N W P Brevé, H V Winter, H M J Van Overzee, E D Farrell, P A Walker
The primary aim of this long-term angler-led tagging programme was to gain information about seasonal changes in distribution of the starry smooth-hound shark Mustelus asterias, along the Dutch coast for management and conservation purposes. Between 2011 and 2014, M. asterias comprised 92·6% (n = 2418) of the total elasmobranch catch (n = 2612) by the licenced group of taggers within the Dutch Delta of which 2244 M. asterias were fin-tagged with plastic rototags. Sex and total length (LT ) composition inside the eastern tidal basin (Oosterschelde) were significantly different, i...
August 2016: Journal of Fish Biology
https://www.readbyqxmd.com/read/27220618/corticotropin-releasing-hormone-family-evolution-five-ancestral-genes-remain-in-some-lineages
#19
João C R Cardoso, Christina A Bergqvist, Rute C Félix, Dan Larhammar
The evolution of the peptide family consisting of corticotropin-releasing hormone (CRH) and the three urocortins (UCN1-3) has been puzzling due to uneven evolutionary rates. Distinct gene duplication scenarios have been proposed in relation to the two basal rounds of vertebrate genome doubling (2R) and the teleost fish-specific genome doubling (3R). By analyses of sequences and chromosomal regions, including many neighboring gene families, we show here that the vertebrate progenitor had two peptide genes that served as the founders of separate subfamilies...
July 2016: Journal of Molecular Endocrinology
https://www.readbyqxmd.com/read/27095494/a-shared-role-for-sonic-hedgehog-signalling-in-patterning-chondrichthyan-gill-arch-appendages-and-tetrapod-limbs
#20
J Andrew Gillis, Brian K Hall
Chondrichthyans (sharks, skates, rays and holocephalans) possess paired appendages that project laterally from their gill arches, known as branchial rays. This led Carl Gegenbaur to propose that paired fins (and hence tetrapod limbs) originally evolved via transformation of gill arches. Tetrapod limbs are patterned by asonic hedgehog(Shh)-expressing signalling centre known as the zone of polarising activity, which establishes the anteroposterior axis of the limb bud and maintains proliferative expansion of limb endoskeletal progenitors...
April 15, 2016: Development
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