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https://www.readbyqxmd.com/read/28944559/harnessing-photochemical-shrinkage-in-direct-laser-writing-for-shape-morphing-of-polymer-sheets
#1
Anton A Bauhofer, Sebastian Krödel, Jan Rys, Osama R Bilal, Andrei Constantinescu, Chiara Daraio
Structures that change their shape in response to external stimuli unfold possibilities for more efficient and versatile production of 3D objects. Direct laser writing (DLW) is a technique based on two-photon polymerization that allows the fabrication of microstructures with complex 3D geometries. Here, it is shown that polymerization shrinkage in DLW can be utilized to create structures with locally controllable residual stresses that enable programmable, self-bending behavior. To demonstrate this concept, planar and 3D-structured sheets are preprogrammed to evolve into bio-inspired shapes (lotus flowers and shark skins)...
September 25, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28944520/human-activities-as-a-driver-of-spatial-variation-in-the-trophic-structure-of-fish-communities-on-pacific-coral-reefs
#2
Jonathan L W Ruppert, Laurent Vigliola, Michel Kulbicki, Pierre Labrosse, Marie-Josée Fortin, Mark G Meekan
Anthropogenic activities such as land-use change, pollution and fishing impact the trophic structure of coral reef fishes, which can influence ecosystem health and function. Although these impacts may be ubiquitous, they are not consistent across the tropical Pacific Ocean. Using an extensive database of fish biomass sampled using underwater visual transects on coral reefs, we modelled the impact of human activities on food webs at Pacific-wide and regional (1,000s-10,000s km) scales. We found significantly lower biomass of sharks and carnivores, where there were higher densities of human populations (hereafter referred to as human activity); however, these patterns were not spatially consistent as there were significant differences in the trophic structures of fishes among biogeographic regions...
September 25, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28940897/effects-of-sample-cleaning-and-storage-on-the-elemental-composition-of-shark-vertebrae
#3
John A Mohan, Thomas C TinHan, Nathan R Miller, R J David Wells
RATIONALE: Application of vertebral chemistry in elasmobranchs has the potential to progress our understanding of individual migration patterns and population dynamics. However, the influence of handling artifacts such as sample cleaning and storage on vertebral chemistry is unclear and requires experimental investigation. METHODS: Vertebrae centra from blacktip sharks (Carcharhinus limbatus) were cleaned with bleach (NaOCl) for five minutes (m), 1 hour (h) and 24 (h) in a cleaning experiment and stored frozen, in 70% ethanol, and 10% formalin treatments for 20 days in a storage experiment...
September 20, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28938002/regional-endothermy-as-a-trigger-for-gigantism-in-some-extinct-macropredatory-sharks
#4
Humberto G Ferrón
Otodontids include some of the largest macropredatory sharks that ever lived, the most extreme case being Otodus (Megaselachus) megalodon. The reasons underlying their gigantism, distribution patterns and extinction have been classically linked with climatic factors and the evolution, radiation and migrations of cetaceans during the Paleogene. However, most of these previous proposals are based on the idea of otodontids as ectothermic sharks regardless of the ecological, energetic and body size constraints that this implies...
2017: PloS One
https://www.readbyqxmd.com/read/28934371/some-like-it-hot-repeat-migration-and-residency-of-whale-sharks-within-an-extreme-natural-environment
#5
David P Robinson, Mohammed Y Jaidah, Steffen S Bach, Christoph A Rohner, Rima W Jabado, Rupert Ormond, Simon J Pierce
The Arabian Gulf is the warmest sea in the world and is host to a globally significant population of the whale shark Rhincodon typus. To investigate regional whale shark behaviour and movements, 59 satellite-linked tags were deployed on whale sharks in the Al Shaheen area off Qatar from 2011-14. Four different models of tag were used throughout the study, each model able to collect differing data or quantities of data. Retention varied from one to 227 days. While all tagged sharks crossed international maritime boundaries, they typically stayed within the Arabian Gulf...
2017: PloS One
https://www.readbyqxmd.com/read/28933440/sharks-can-live-a-lot-longer-than-researchers-realized
#6
Daniel Cressey
No abstract text is available yet for this article.
September 20, 2017: Nature
https://www.readbyqxmd.com/read/28931746/voltage-gated-sodium-channel-gene-repertoire-of-lampreys-gene-duplications-tissue-specific-expression-and-discovery-of-a-long-lost-gene
#7
Harold H Zakon, Weiming Li, Nisha E Pillai, Sumanty Tohari, Prashant Shingate, Jianfeng Ren, Byrappa Venkatesh
Studies of the voltage-gated sodium (Nav) channels of extant gnathostomes have made it possible to deduce that ancestral gnathostomes possessed four voltage-gated sodium channel genes derived from a single ancestral chordate gene following two rounds of genome duplication early in vertebrates. We investigated the Nav gene family in two species of lampreys (the Japanese lamprey Lethenteron japonicum and sea lamprey Petromyzon marinus) (jawless vertebrates-agnatha) and compared them with those of basal vertebrates to better understand the origin of Nav genes in vertebrates...
September 27, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28927318/the-mitogenomic-phylogeny-of-the-elasmobranchii-chondrichthyes
#8
Cesar R L Amaral, Filipe Pereira, Dayse A Silva, António Amorim, Elizeu F de Carvalho
Here we present a mitogenomic perspective on the evolution of sharks and rays, being a first glance on the complete mitochondrial history of such an old and diversified group of vertebrates. The Elasmobranchii is a diverse subclass of Chondrichthyes, or cartilaginous fish, with about 1200 species of ocean- and freshwater-dwelling fishes spread all over the world's seas, including some of the ocean's largest fishes. The group dates back about 400 million years near the Devonian-Silurian boundary, being nowadays represented by several derivative lineages, mainly related to Mesozoic forms...
September 20, 2017: Mitochondrial DNA. Part A. DNA Mapping, Sequencing, and Analysis
https://www.readbyqxmd.com/read/28926627/tiger-sharks-can-connect-equatorial-habitats-and-fisheries-across-the-atlantic-ocean-basin
#9
André S Afonso, Ricardo Garla, Fábio H V Hazin
Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier) population structure off the oceanic insular system of Fernando de Noronha (FEN) and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry...
2017: PloS One
https://www.readbyqxmd.com/read/28924159/live-bearing-without-placenta-physical-estimation-indicates-the-high-oxygen-supplying-ability-of-white-shark-uterus-to-the-embryo
#10
Taketeru Tomita, Ryo Nozu, Masaru Nakamura, Shohei Matsuzaki, Kei Miyamoto, Keiichi Sato
One of the mysteries of shark aplacental viviparity is the ability of the embryos to acquire oxygen from their mothers without a placental connection. It has been assumed that embryonic respiration in aplacental viviparous shark depends on oxygen from the uterine wall, although this hypothesis has not been confirmed quantitatively. Morphological observations of the uterine wall of white shark (Carcharodon carcharias) provided the first quantitative evidence to support the ability of the uterus to supply ample oxygen to the embryo of viviparous elasmobranchs...
September 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28923557/a-molecular-approach-towards-taxonomic-identification-of-elasmobranch-species-from-maltese-fisheries-landings
#11
Adriana Vella, Noel Vella, Sarah Schembri
The mitochondrial genome, through the application of DNA barcoding, provides a powerful tool for identifying species even when specimens are either incomplete or belong to species that exhibit cryptic diversity. In fisheries management accurate identification of whole or part of the specimens landed is a fundamental requirement for the conservation of species affected directly or indirectly by the fisheries activities. In this study cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 2 (ND2) sequences were used to genetically distinguish 36 elasmobranch species collected from Maltese (Central Mediterranean) commercial fisheries landings...
September 8, 2017: Marine Genomics
https://www.readbyqxmd.com/read/28923317/calcified-cartilage-or-bone-collagens-in-the-tessellated-endoskeletons-of-cartilaginous-fish-sharks-and-rays
#12
Ronald Seidel, Michael Blumer, Elisabeth-Judith Pechriggl, Kady Lyons, Brian K Hall, Peter Fratzl, James C Weaver, Mason N Dean
The primary skeletal tissue in elasmobranchs -sharks, rays and relatives- is cartilage, forming both embryonic and adult endoskeletons. Only the skeletal surface calcifies, exhibiting mineralized tiles (tesserae) sandwiched between a cartilage core and overlying fibrous perichondrium. These two tissues are based on different collagens (Coll II and I, respectively), fueling a long-standing debate as to whether tesserae are more like bone (Coll 1-based) or calcified cartilage in their matrix composition. We demonstrate that stingray (Urobatis halleri) tesserae are bipartite, having an upper Coll I-based "cap" that merges into a lower Coll II-based "body" zone, although tesserae are surrounded by cartilage...
September 15, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28920792/squamous-cell-carcinoma-of-the-rostral-maxilla-in-an-adult-captive-whitespotted-bamboo-shark-chiloscyllium-plagiosum
#13
Betsy E Culp, Martin Haulena, Kelly Britt, Hannah Evans, Stephen Raverty
An approximately 10-yr-old adult female whitespotted bamboo shark (Chiloscyllium plagiosum) presented with a smooth, white, irregular, ulcerated, and expansile lesion on the left lateral aspect of the maxillary rostrum. The lesion had short periods of abrupt and rapid proliferation and then remained static for several months. Cytology and culture were nonspecific and did not reveal any discernible etiologic agents or cellular atypia. The lesion was nonresponsive to parenteral antibiotics. One year after the initial onset of the lesion, the ulcer was 10 cm in diameter, a percentage increase in size of 455%...
September 2017: Journal of Zoo and Wildlife Medicine: Official Publication of the American Association of Zoo Veterinarians
https://www.readbyqxmd.com/read/28906448/valorization-of-by-products-from-commercial-fish-species-extraction-and-chemical-properties-of-skin-gelatins
#14
Sérgio C Sousa, José A Vázquez, Ricardo I Pérez-Martín, Ana P Carvalho, Ana M Gomes
Fish skins constitute an important fraction of the enormous amount of wastes produced by the fish processing industry, part of which may be valorized through the extraction of gelatins. This research exploited the extraction and characterization of gelatins from the skin of three seawater fish species, namely yellowfin tuna (Thunnus albacares), blue shark (Prionace glauca), and greenland halibut (Reinhardtius hippoglossoides). Characterization included chemical composition, rheology, structure, texture, and molecular weight, whereas extraction studies intended to reduce costly steps during extraction process (reagents concentration, water consumption, and time of processing), while maintaining extraction efficiency...
September 14, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28901006/reproductive-aspects-of-the-atlantic-angel-shark-squatina-dumeril-in-the-southern-caribbean-sea
#15
A Tagliafico, S Rangel, M K Broadhurst
The maturity and reproduction of the Atlantic angel shark Squatina dumeril were assessed using 77 females (29·2-110·4 cm total length; LT ) and 269 males (58·7-108·2 cm LT ) harvested by artisanal gillnetters off Venezuela. The biased sex ratio implied segregation or sex-specific gear selectivity. Based on the development of the reproductive tract, 50% LT at sexual maturity (LT50 , mean ± s.e.) for females and males were estimated at 86·14 ± 0·64 and 81·55 ± 0·12 cm, respectively...
September 12, 2017: Journal of Fish Biology
https://www.readbyqxmd.com/read/28887553/insight-into-shark-magnetic-field-perception-from-empirical-observations
#16
James M Anderson, Tamrynn M Clegg, Luisa V M V Q Véras, Kim N Holland
Elasmobranch fishes are among a broad range of taxa believed to gain positional information and navigate using the earth's magnetic field, yet in sharks, much remains uncertain regarding the sensory receptors and pathways involved, or the exact nature of perceived stimuli. Captive sandbar sharks, Carcharhinus plumbeus were conditioned to respond to presentation of a magnetic stimulus by seeking out a target in anticipation of reward (food). Sharks in the study demonstrated strong responses to magnetic stimuli, making significantly more approaches to the target (p = < 0...
September 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28883085/hydrodynamic-function-of-dorsal-fins-in-spiny-dogfish-and-bamboo-sharks-during-steady-swimming
#17
Anabela Maia, George V Lauder, Cheryl D Wilga
A key feature of fish functional design is the presence of multiple fins that allow thrust vectoring and redirection of fluid momentum to contribute to both steady swimming and maneuvering. A number of previous studies have analyzed the function of dorsal fins in teleost fishes in this context, but the hydrodynamic function of dorsal fins in freely-swimming sharks has not been analyzed, despite the potential for differential functional roles between the anterior and posterior dorsal fins. Previous anatomical research has suggested a primarily stabilizing role for shark dorsal fins...
September 7, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28882216/biodiversity-life-history-and-conservation-of-northeastern-pacific-chondrichthyans
#18
David A Ebert, Jennifer S Bigman, Julia M Lawson
The sharks, batoids, and chimaeras, collectively the class Chondrichthyes, are one of the most successful groups of fishes, with over 1250 species globally. Recent taxonomic revisions have increased their diversity by about 20% over the past 17 years (2000-2016). The Northeast Pacific Ocean is one of the top 20 most diverse regions/countries on the globe with 77 chondrichthyan species, a number less than a quarter that of the most species-rich area (Australia) but that has increased by 10% since 2000 to include three new species (two skates and a chimaera)...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/28882215/review-of-current-conservation-genetic-analyses-of-northeast-pacific-sharks
#19
Shawn E Larson, Toby S Daly-Engel, Nicole M Phillips
Conservation genetics is an applied science that utilizes molecular tools to help solve problems in species conservation and management. It is an interdisciplinary specialty in which scientists apply the study of genetics in conjunction with traditional ecological fieldwork and other techniques to explore molecular variation, population boundaries, and evolutionary relationships with the goal of enabling resource managers to better protect biodiversity and identify unique populations. Several shark species in the northeast Pacific (NEP) have been studied using conservation genetics techniques, which are discussed here...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/28882213/stable-isotope-applications-for-understanding-shark-ecology-in-the-northeast-pacific-ocean
#20
Jonathan C P Reum, Gregory D Williams, Chris J Harvey
Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e...
2017: Advances in Marine Biology
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