Littérature scientifique sur le sujet « Sharks Physiology »
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Articles de revues sur le sujet "Sharks Physiology"
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Leigh, Samantha C., Yannis Papastamatiou et Donovan P. German. « The nutritional physiology of sharks ». Reviews in Fish Biology and Fisheries 27, no 3 (25 mai 2017) : 561–85. http://dx.doi.org/10.1007/s11160-017-9481-2.
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Whitney, Nicholas M., Karissa O. Lear, John J. Morris, Robert E. Hueter, John K. Carlson et Heather M. Marshall. « Connecting post-release mortality to the physiological stress response of large coastal sharks in a commercial longline fishery ». PLOS ONE 16, no 9 (15 septembre 2021) : e0255673. http://dx.doi.org/10.1371/journal.pone.0255673.
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Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery. Blood was sampled from the same individuals that were tagged, providing direct correlation between stress physiology and animal fate for sandbar (Carcharhinus plumbeus, N = 130), blacktip (C. limbatus, N = 105), tiger (Galeocerdo cuvier, N = 52), spinner (C. brevipinna, N = 14), and bull sharks (C. leucas, N = 14). PRM rates ranged from 2% and 3% PRM in tiger and sandbar sharks to 42% and 71% PRM in blacktip and spinner sharks, respectively. Decision trees based on blood values predicted mortality with >67% accuracy in blacktip and spinner sharks, and >99% accuracy in sandbar sharks. Ninety percent of PRM occurred within 5 h after release and 59% within 2 h. Blood physiology indicated that PRM was primarily associated with acidosis and increases in plasma potassium levels. Total fishing mortality reached 62% for blacktip and 89% for spinner sharks, which may be under-estimates given that some soak times were shortened to focus on PRM. Our findings suggest that no-take regulations may be beneficial for sandbar, tiger, and bull sharks, but less effective for more susceptible species such as blacktip and spinner sharks.
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Kelly, Michael L., Errol R. P. Murray, Caroline C. Kerr, Craig A. Radford, Shaun P. Collin, John A. Lesku et Jan M. Hemmi. « Diverse Activity Rhythms in Sharks (Elasmobranchii) ». Journal of Biological Rhythms 35, no 5 (11 juin 2020) : 476–88. http://dx.doi.org/10.1177/0748730420932066.
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Sharks are an interesting group of vertebrates, as many species swim continuously to “ram” oxygen-rich seawater over their gills (ram ventilators), whereas other species “pump” seawater over their gills by manipulating buccal cavity volume while remaining motionless (buccal pumpers). This difference in respiratory physiology raises the question: What are the implications of these differences in lifestyle for circadian rhythms? We investigated the diel activity patterns of 5 species of sharks, including 3 ram ventilating species: the school shark ( Galeorhinus galeus), the spotted estuary smooth-hound ( Mustelus lenticulatus), and the spiny dogfish ( Squalus acanthias); and 2 buccal pumping species: the Port Jackson ( Heterodontus portusjacksoni) and draughtsboard ( Cephaloscyllium isabellum) sharks. We measured the amount, duration, and distance traveled while swimming over multiple days under a 12:12 light:dark light regime for all species and used modified light regimes for species with a clear diel rhythm in activity. We identified a surprising diversity of activity rhythms. The school shark and smooth-hound swam continuously; however, whereas the school shark swam at the same speed and covered the same distance during the day and night, the smooth-hound swam slower at night and traversed a shorter distance. A similar pattern was observed in the spiny dogfish, although this shark swam less overall. Both the Port Jackson and draughtsboard sharks showed a marked nocturnal preference for swimming. This pattern was muted and disrupted during constant light and constant dark regimes, although circadian organization of this pattern was maintained under certain conditions. The consequences of these patterns for other biological processes, such as sleep, remain unclear. Nonetheless, these 5 species demonstrate remarkable diversity within the activity rhythms of sharks.
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Benson, C. W., B. D. Shea, C. de Silva, D. Donovan, P. E. Holder, S. J. Cooke et A. J. Gallagher. « Physiological consequences of varying large shark exposure on striped bass (Morone saxatilis) ». Canadian Journal of Zoology 97, no 12 (décembre 2019) : 1195–202. http://dx.doi.org/10.1139/cjz-2019-0173.
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Large marine predators often aggregate seasonally in discrete locations to take advantage of optimal foraging conditions, leading to spatial and temporal variation in their exposure on other species. However, our understanding of the impacts this exposure may have on the behavior and physiology of prey is poor, especially in marine systems. Here, we evaluated the non-consumptive effects of potential exposure to large sharks (white sharks, Carcharodon carcharias (Linnaeus, 1758)) on the stress physiology of an economically important teleost, the striped bass (Morone saxatilis (Walbaum, 1792)), off Cape Cod, Massachusetts, USA. We sampled fish in habitats that varied significantly in shark exposure across 5 months and over 2 years, evaluating blood physiology stress indicators (i.e., cortisol, glucose, and lactate concentrations) and reflex impairment. None of the blood parameters were influenced by shark exposure, although we did observe subtle temperature and seasonal effects. One of the three reflex tests (the vertical orientation test) was negatively affected by shark exposure, although the mechanistic basis for this finding is unclear. This work supports the notion that predictable sources of predation pressure tend not to manifest in stress-related costs in free-ranging prey, which has implications for shaping our understanding of how large sharks influence ecosystems through non-consumptive effects.
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Esposito, Anaïs, Pierre Sasal, Éric Clua, Emese Meglécz et Camille Clerissi. « Shark Provisioning Influences the Gut Microbiota of the Black-Tip Reef Shark in French Polynesia ». Fishes 7, no 6 (29 octobre 2022) : 312. http://dx.doi.org/10.3390/fishes7060312.
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There is an increasing interest in touristic observations of top predators in the wild. Sharks are probably the most sought-after animal in marine ecosystems by divers. Regulations have been put in place, and even if they are more or less respected, providing food is still used in some places in order to attract wild animals. Because of the difficulty in sampling shark guts, few studies have analyzed the microbiota of sharks, and none have evaluated the effect of feeding on this microbiota. In this work, we compare microbiota assemblages of black-tip sharks between sites with and without regular feeding. Our results revealed a significant feeding effect on both alpha and beta diversities of microbiota. Notably, the alpha diversity of fed sharks was lower than unfed sharks. We hypothesize that this result is related to a lower diversity of food intake by sharks in places where feeding is regularly provided. More studies need to be conducted in order to estimate the impact of feeding on shark physiology.
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Johnston, Emmett M., Lewis G. Halsey, Nicholas L. Payne, Alison A. Kock, Gil Iosilevskii, Bren Whelan et Jonathan D. R. Houghton. « Latent power of basking sharks revealed by exceptional breaching events ». Biology Letters 14, no 9 (septembre 2018) : 20180537. http://dx.doi.org/10.1098/rsbl.2018.0537.
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The fast swimming and associated breaching behaviour of endothermic mackerel sharks is well suited to the capture of agile prey. In contrast, the observed but rarely documented breaching capability of basking sharks is incongruous to their famously languid lifestyle as filter-feeding planktivores. Indeed, by analysing video footage and an animal-instrumented data logger, we found that basking sharks exhibit the same vertical velocity (approx. 5 m s −1 ) during breach events as the famously powerful predatory great white shark. We estimate that an 8-m, 2700-kg basking shark, recorded breaching at 5 m s −1 and accelerating at 0.4 m s −2 , expended mechanical energy at a rate of 5.5 W kg −1 ; a mass-specific energetic cost comparable to that of the great white shark. The energy cost of such a breach is equivalent to around 1/17th of the daily standard metabolic cost for a basking shark, while the ratio is about half this for a great white shark. While breaches by basking sharks must serve a different function to white shark breaches, their similar breaching speeds questions our perception of the physiology of large filter-feeding fish.
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Gallagher, Austin J., Erica R. Staaterman, Steven J. Cooke et Neil Hammerschlag. « Behavioural responses to fisheries capture among sharks caught using experimental fishery gear ». Canadian Journal of Fisheries and Aquatic Sciences 74, no 1 (janvier 2017) : 1–7. http://dx.doi.org/10.1139/cjfas-2016-0165.
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The response to capture is important in fisheries because it can reveal potential threats to species beyond fishing mortalities resulting from direct harvest. To date, the vast majority of studies assessing shark stress responses have used physiology or biotelemetry to look at sensitivity after capture, leaving a gap in our understanding of the behaviours of sharks during capture. We examined the behavioural responses of sharks to capture by attaching accelerometers to fishing gear and measuring the immediate and prolonged forces they exerted while on the line. We recorded acceleration vectors and derived the rate of intense fighting behaviours of 23 individual sharks comprising three species. Results suggest that blacktip sharks (Carcharhinus limbatus) exhibited intense bouts of fighting behaviour at the onset of hooking, while nurse (Ginglymostoma cirratum) and tiger sharks (Galeocerdo cuvier) displayed more subdued acceleration values during capture. We also obtained plasma lactate from a subset of individuals and detected a strong correlation with maximum acceleration. These results align with previously published values and suggest that shark movement during fisheries capture is an important factor during bycatch and catch-and-release interactions.
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Bouyoucos, IA, CA Simpfendorfer, S. Planes, GD Schwieterman, OC Weideli et JL Rummer. « Thermally insensitive physiological performance allows neonatal sharks to use coastal habitats as nursery areas ». Marine Ecology Progress Series 682 (20 janvier 2022) : 137–52. http://dx.doi.org/10.3354/meps13941.
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Coastal sharks can use shallow, nearshore habitats as nursery areas, which is a behaviour that may increase fitness. The ecological benefits of shark nursery areas are well studied; yet the physiological mechanisms that enable sharks to exploit coastal habitats, especially those that experience extreme and dynamic temperatures, remain understudied. We hypothesised that neonatal sharks are able to use thermally dynamic coastal habitats as nursery areas because temperature does not strongly affect their physiology. To test this hypothesis, we defined patterns of nursery area use and temperature-dependent physiological performance in 2 reef shark species. First, we determined whether 10 sites around the island of Moorea, French Polynesia, satisfied nursery area criteria for neonate populations of blacktip reef sharks Carcharhinus melanopterus and sicklefin lemon sharks Negaprion acutidens using 5 consecutive years of abundance surveys. We then quantified effects of thermal exposure in situ on growth in recaptured individuals and quantified the temperature dependence of metabolic rate ex situ using respirometry. We found several potential C. melanopterus nursery areas, but during different sampling years, and identified 1 N. acutidens nursery area that remained consistent during the entire 5 yr study. In support of our hypothesis, growth and metabolic performance were not strongly affected by temperature in either species. Thus, thermally insensitive physiological performance may be a trait that elasmobranchs exhibit in thermally variable coastal habitats, including shark nursery areas. Together, this approach demonstrates how physiological and ecological concepts complement each other to improve our understanding of nursery area use in coastal shark populations.
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Jacoby, David M. P., Penthai Siriwat, Robin Freeman et Chris Carbone. « Is the scaling of swim speed in sharks driven by metabolism ? » Biology Letters 11, no 12 (décembre 2015) : 20150781. http://dx.doi.org/10.1098/rsbl.2015.0781.
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The movement rates of sharks are intrinsically linked to foraging ecology, predator–prey dynamics and wider ecosystem functioning in marine systems. During ram ventilation, however, shark movement rates are linked not only to ecological parameters, but also to physiology, as minimum speeds are required to provide sufficient water flow across the gills to maintain metabolism. We develop a geometric model predicting a positive scaling relationship between swim speeds in relation to body size and ultimately shark metabolism, taking into account estimates for the scaling of gill dimensions. Empirical data from 64 studies (26 species) were compiled to test our model while controlling for the influence of phylogenetic similarity between related species. Our model predictions were found to closely resemble the observed relationships from tracked sharks, providing a means to infer mobility in particularly intractable species.
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Ritter, Erich. « Sharks and their Relatives II : Biodiversity, Adaptive Physiology and Conservation ». Bulletin of Marine Science 87, no 1 (1 janvier 2011) : 155–56. http://dx.doi.org/10.5343/bms.br.2011.0001.
Texte intégralThèses sur le sujet "Sharks Physiology"
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Dowd, W. Wesley. « Metabolic Rates and Bioenergetics of Juvenile Sandbar Sharks (Carcharhinus plumbeus) ». W&M ScholarWorks, 2003. http://www.vims.edu/library/Theses/Dowd03.pdf.
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Gennari, Enrico. « Thermal physiology and behavioural ecology of the white shark, carcharodon carcharias ». Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/64002.
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Gardiner, Jayne M. « Multisensory Integration in Shark Feeding Behavior ». Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4046.
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Multimodal sensory input directs simple and complex behaviors in animals. Most research to date has been limited to studies of individual senses rather than multiple senses working together, leading to important advances in our comprehension of the sensory systems in isolation, but not their complementary and alternative roles in difficult behavioral tasks, such as feeding. In the marine environment, a prey item might emit an odor, create a hydrodynamic disturbance, such as from gill movements or swimming, be visible to the predator, produce a sound, and/or produce a weak electrical field. Therefore, the goal of this study was to investigate the integration of olfaction, mechanoreception by the lateral line system, vision, and electroreception in a marine animal. Sharks were chosen as a model organism in which to investigate multisensory integration because of their sensitivity and acuity, the presence of the same suite of sensory modalities in all species, the availability of experimental animals from different species, habitats and ecologies, and the rich literature on sharks' prey capture behavior. Two approaches were used: controlled artificial stimuli, delivered to the animals, were used to determine the spatial and concentration characteristics of odor encounters that guide the initial orientation to an odor plume in the far field in a model elasmobranch, the smooth dogfish, Mustelus canis; and sensory deprivation was used to restrict the availability of natural cues emanating from live prey items in order to elucidate the complementary and alternating roles of the senses in detecting, tracking, orienting to, striking at, and ultimately capturing prey. In the latter experiments, three species of sharks from different ecological niches were investigated: benthic, suction-feeding nurse sharks (Ginglymostoma cirratum) that hunt nocturnally for fish; ram-biting bonnetheads (Sphyrna tiburo) that scoop crustaceans off the bottom of seagrass beds; and ram-feeding blacktip sharks (Carcharhinus limbatus) that rapidly chase down midwater teleost prey. In orienting to odor patches, bilateral time differences between the nares are more important than concentration differences, such that animals turn toward the side stimulated first, even with delayed pulses of higher concentration. This response would steer the shark into each oncoming odor patch, helping the animal maintain contact with an odor plume. Sensory deprivation experiments revealed similarities and differences among species in terms of which senses they choose to focus on for particular behaviors, likely as a result of differences in the environments that they hunt in, type of prey consumed, and foraging strategies used, as well as anatomical differences in the central nervous system and the sensory organs. In most cases, multiple senses can be used for the same behavioral task. Thus, sharks are capable of successfully capturing prey, even when the optimal sensory cues are unavailable, by switching to alternative sensory modalities, which indicates that feeding behavior is plastic. Nurse sharks rely primarily on olfaction for detection. Olfaction in combination with vision, the lateral line, or touch is required for tracking. Nurse sharks orient to prey using the lateral line, vision, or electroreception, but will not ingest food if olfaction is blocked. Capture is mediated by the electrosensory system or tactile cues. Bonnetheads normally detect prey using olfaction, rely on olfactory-based tracking until they are close to the prey, then vision to line up a strike, and finally electroreception to time the jaw movements for capture. They can detect, orient, and strike visually in the absence of olfactory cues. Blacktip sharks also detect prey using olfaction or vision. Olfaction is used in combination with vision or the lateral line system for tracking. Long-distance orientation and striking is visually mediated, but strike precision relies on lateral line cues and an increase in misses occurs when this system is blocked. In the absence of vision, short-range orientation and striking can occur using lateral line cues. Capture is mediated by electroreception or tactile cues. Collectively, these results were used to develop species-specific sensory hierarchies for shark feeding behavior in a captive environment, the first such hierarchies to cover a complete behavioral sequence in a vertebrate.
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Hoggatt, April Marie. « Mab anti-type I and Mab anti-zebrin II labelling in two siluriform fishes : the role of shared lineage versus shared function in polypeptide co-distributions ». Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/902481.
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Two monoclonal antibodies (mabs), the newly generated mab anti-type I and the previously documented mab anti-zebrin II, were reacted with brainstem sections of two ostariophysan siluriforms, the gymnotoid Rhamphichthys rostratus and the siluroid Ictalurus punctatus. Mab anti-type I recognizes a 47 kD polypeptide present in the dendrites and soma of projection neurons. Mab anti-zebrin II recognizes a 36 kD polypeptide present throughout the neuronal cytoplasm, including the axon. Strongly type I immunopositive cells include all cerebellar Purkinje cells, pyramidal cells of the nucleus medialis, electrosensory lateral line lobe, and tectum, pacemaker relay cells, Mauthner neurons, lateral line ganglion cells, and cells of the reticular formation, lateral reticular nucleus, and inferior olive. Weakly reactive type I cells include neurons in the torus semicircularis, medial and efferent octavolateralis nuclei, magnocellular and lateral tegmentum, and motor neurons of the Vth, V I Ith, and Xth cranial nerves. All type I positive cells are projection neurons. Zebrin II expression is restricted to subsets of two cell types which also express the type I antigen -- Purkinje cells and developing acousticolateralis pyramidal cells. Both of these neurons develop from the region of the rhombic lip. Thus, the mutual expression of the type I antigen can be explained by the shared function of projection neurons, while the common expression of the zebrin II antigen may be due to a shared embryological lineage.Department of Physiology and Health Science
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Tompkins, Linda Suzanne. « Molecular mechanisms of glucose-sensing shared by insulin-secreting cells and glucose-sensing neurons of the rat hypothalamus ». Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/279863.
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Fundamental to life is the ability to acquire and assimilate nutrients. Individual cell types exhibit preferences for different nutrients, but only certain cells utilize nutrients as signaling molecules. The most intensely studied nutrient signaling system is the pancreatic beta cell, which secretes insulin in response to changes in blood glucose. Another glucose sensing system is found in the neurons within the hypothalamus of the brain. To study how single cells sense changes in glucose, a sensitive marker for secretion is required. To this end the human Growth Hormone (hGH) gene was fused to the 5' end of the enhanced Green Fluorescent Protein (GFP) gene and expressed in the RIN-1038 beta (β)-cell line. The hGH-GFP fusion protein was targeted to secretory granules and its secretion into culture media was detected from cell populations. At stimulatory levels of glucose (5 mM), hGH-EGFP secretion doubled, and potentiators of insulin secretion enhanced glucose-induced hGH-EGFP release. However, at the single cell level, hGH-EGFP fluorescence acted as a sensor for changes in secretory granule pH. Glucose induced granule acidification by increasing activity of the V-type proton ATPase resident in the vesicular membrane. Moreover, potentiators of secretion elicited alkalinization of the vesicle lumen suggesting a mechanism by which they enhance release. To compare components of the glucose-sensing mechanism of hypothalamic neurons to those described for the beta cell, RT-PCR analysis was performed on RNA samples taken from the Arcuate nucleus (ARC), Lateral Hypothalamus (LH), Paraventricular Hypothalamus (PVH) and Ventromedial Hypothalamus (VMH). Tissue-specific expression of Glucokinase (GK), Glucokinase Regulatory Protein (GKRP), Glucose transporter isoforms (GLUT) 1, 2, 3 and X1 genes were determined. GK gene expression was found in all hypothalamic regions, with highest levels in the ARC. Enzymatic activity assays show that GK activity accounts for approximately 20% of the total soluble hexokinase activity in pooled samples of ARC and VMH. All regions also express GLUT 1, 3 and X1. However, no GLUT-2 or GKRP mRNA was detected in any sample. Because the expression of the low K(m) GLUTS predominates and GKRP expression is absent, the hypothalamic glucose-sensing mechanism is adapted to the lower levels of glucose present in the cerebrospinal fluid compared to blood levels.
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Bouyoucos, Ian. « Les effets des conditions du changement climatique prévues sur les requins tropicaux ». Thesis, Université Paris sciences et lettres, 2020. https://tel.archives-ouvertes.fr/tel-02889401.
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Les requins sont menacés aux causes anthropiques ; mais, les conséquences qu’une menace nouveau, le changement climatique, sont mal connus. Pour ma thèse, j’ai testé l’hypothèse que le changement climatique agira sur les performances physiologiques des requins tropicaux pour réduire la valeur sélective. Mes objectives sont d’évaluer les effets des zones « nurseries » sur la performance physiologique, la performance physiologique in situ, les performances, préférences, et tolérances thermiques, et les effets du réchauffement et de l’acidification des océans sur la performance physiologique. J’ai trouvé que les requins pointes noires (Carcharhinus melanopterus) ont la croissance supérieure dans les zones nurseries mais l’acidification et le réchauffement agissent en synergie à la réduire. Mes résultats suggèrent que le changement climatique va réduire la valeur sélective des requins tropicaux par les effets sur les performances physiologiques qui sont associés aux zones nurseriesMyriad anthropogenic impacts drive declines in global shark populations; yet, the consequences of a newly recognised threat, global climate change, are poorly understood. This thesis tested the hypothesis that global change stressors (ocean acidification and warming) reduce fitness in tropical reef sharks via effects on physiological performance. My specific objectives were to define thermal performance in fitness-enhancing nursery areas, physiological performance in situ, associations between thermal performance, preference, and tolerance, and physiological performance under multiple global change stressors. I found that neonatal blacktip reef sharks (Carcharhinus melanopterus) have superior growth efficiency in nursery areas relative to other habitats, but ocean acidification and warming synergistically reduce performance. This thesis suggests that global change stressors reduce fitness in tropical reef sharks by acting on physiological traits that are associated with nursery areas
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Brooks, Edward James. « Elasmobranch longline capture : ecological application, physiological impacts and alternative techniques ». Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/1570.
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Longline fishing is the most common elasmobranch capture method in the world, both for commercial fishing, and to a lesser extent for scientific surveys. The capture of an animal on a longline initiates a series of physiological responses designed to promote survivorship in the short term, but if unchecked, can cause reduced individual fitness and/or mortality in the long term. Given widespread declines in shark populations, an improved understanding of the physiological costs of longline capture is needed. The aim of this thesis was to investigate the physiological response of sharks to capture and restraint, to assess novel, non-invasive alternatives to scientific longline surveys, and to generate scientific insight into poorly understood elasmobranch populations in The Bahamas. The results presented herein suggest that some species of shark are able to recover from the physiological stress of capture despite the presence of persistent negative stimuli. Tonic immobility was assessed as a means of generating baseline blood chemistry data, but was found to be inappropriate given that it increases the magnitude of physiological perturbation in the short term. To avoid the stress of capture altogether, Baited Remote Underwater Video Surveys (BRUVS) were considered as a non-invasive alternative to capture based surveys, however, it was concluded that they lack the resolution necessary to answer fine scale demographic questions. For the Caribbean reef shark, longline surveys yielded high resolution data allowing the identification of fine scale spatiotemporal shifts in demographic population structure with minimal cost (mortality). Nevertheless, the ethics of using capture based surveys on sensitive species are questionable when alternative techniques are available. Deep water sharks caught on longline surveys exhibited high mortality rates, however, for these very poorly understood species moribund specimens have great scientific value which in some cases can offset the high ecological costs of the surveys. The results presented in this thesis highlight the on-going need for improved biological and ecological research into the majority of elasmobranch populations, particularly with regards to anthropogenic interactions such as capture. Given the tenuous conservation status of many species, the acquisition of applied, management focused data should remain the priority of elasmobranch scientists.
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Hart, Hannah. « Molecular Identification and Functional Characteristics of Peptide Transporter 1 (PEPT1) in the Bonnethead Shark (Sphyrna tiburo) ». UNF Digital Commons, 2015. http://digitalcommons.unf.edu/etd/610.
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Many elasmobranchs are considered top predators with worldwide distribution, and in general these fish play an important role in the transfer of energy from the lower to the upper trophic levels within the marine ecosystem. Despite this, little research has been done regarding the rates of prey ingestion, digestion, and the processes of energy and nutrient absorption. Specifically understudied is enzymatic digestion within the intestinal brush border, which functions to break down macromolecules into smaller subunits for luminal absorption across the gastrointestinal epithelium. Given their carnivorous diet, the present study sought to expand knowledge on nutrient intake in elasmobranchs by focusing on the uptake of products of protein metabolism. To accomplish this, sequence encoding Peptide Transporter 1 (PepT1), a protein found within the brush border membrane (BBM) of higher vertebrates that is responsible for the translocation and absorption of small peptides released during digestion by luminal and membrane-bound proteases, was molecularly identified in the bonnethead shark (Sphyrna tiburo) using degenerate primers based on conserved portions of known PEPT1 sequences from other vertebrates. Sequence encoding Peptide Transporter 2 (PepT2) was also isolated from the S. tiburo scroll valve intestine using the same methodology. PepT1 was then localized using immunocytochemistry with rabbit polyclonal anti-rat PEPT1 in the esophagus, stomach, duodenum, scroll valve intestine, rectum, and pancreas. Vesicle studies were used to identify the apparent affinity of the transporter, and to quantify the rate of uptake by its H+-dependent cotransporter properties, using 3H-glycylsarcosine as a model dipeptide. The results of this study provide insight into the rate and properties of food passage within S. tiburo, and can lead to future work on topics such as physiological regulation of protein metabolism and absorption and how it may vary in elasmobranchs that exhibit different feeding strategies.
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Zaffaroni, Marta. « Modélisation des interactions plant-puceron, en considérant explicitement le rôle des pratiques agricoles : Pêche (Prunus persica) - puceron vert (Myzus persicae) comme cas d'étude An ecophysiological model of plant–pest interactions : the role of nutrient and water availability Maximizing plant production and minimizing environmental impact : comparing agricultural management scenarios with multi criteria decision analysis The role of vectors interference in a shared host-multi vector system ». Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0723.
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Les pucerons modifient le développement des plantes et peuvent transmettre des virus, représentant ainsi une menace majeure pour les cultures. Il est possible de réduire la pression exercée par les pucerons sur les plantes et d’améliorer la production agricole en facilitant certains processus écologiques en plus ou en remplacement de l’utilisation de pesticides. Les modèles mathématiques peuvent aider à prédire la direction et la force de ces processus écologiques et ils peuvent révéler l’impact des modes alternatifs de gestion des cultures. La thèse proposée vise à développer des modèles mathématiques basés sur les processus, couplant la physiologie des plantes et la démographie des pucerons, afin de favoriser l’intensification écologique et de réduire l’utilisation des pesticides. Les modèles tiennent compte i) des interactions entre la plante et le puceron, alors que la plupart des modèles de culture ne prennent en compte que l’effet du ravageur sur la plante et non l’inverse, ce qui nuit à la compréhension de la lutte antiparasitaire via les pratiques culturales;et ii) de l’effet des pratiques culturales et du résultat en termes de récolte,questions qui sont généralement absentes dans les modèles écologiques. Je couple tout d’abord un modèle mécaniste de croissance des plantes avec un modèle de population des pucerons, je le calibre pour un système pêche-puceron vert et je l’utilise pour obtenir des informations sur les mécanismes qui sous-tendent la réponse des pucerons à la fertilisation et à l’irrigation. En outre, je développe un modèle épidémiologique qui tient compte explicitement de l’interférence entre deux pucerons vecteurs. J’applique ce modèle pour étudier l’effet de l’interférence inter-spécifique des pucerons dans la propagation des virus des plantes, en tenant compte de l’effet des pratiques agricolesAphids alter plant development and can transmit viruses, thus representing a major threat for crops. Aphid pressure on plant can be reduced and crop production can be enhanced by facilitating some ecological processes in addition, or in substitution, to the use of pesticides. Mathematical models can help in predicting the direction and strength of these ecological processes and they can reveal the impact of alternative ways of managing crops. The proposed thesis aims to develop process based mathematical models coupling plant physiology and aphid demography to drive ecological intensification and reduce the use of pesticides. The models consider i) interactions between plant and aphid, while most crop models only consider the effect of the pest on the plant and not vice versa hence impairing insights upon bottom-up pest control via cultural practices; and ii) the effect of cultural practices and the outcome in terms of harvest, issues that are usually absent in ecological models. Therefore, I firstly couple a mechanistic plant growth model with a pest population model, I calibrate it for a peach-green aphid system and I use it to get insights on the mechanisms behind the response of aphids to fertilization and irrigation. Furthermore, I develop an epidemiological model explicitly accounting for the interference between two aphid vectors. I apply the model to explore the effect of inter-specific aphid interference in shaping the spread of plant viruses, considering the effect of agricultural practices
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Wåhlin, Peter. « Enhanching the Human-Team Awareness of a Robot ». Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-16371.
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The use of autonomous robots in our society is increasing every day and a robot is no longer seen as a tool but as a team member. The robots are now working side by side with us and provide assistance during dangerous operations where humans otherwise are at risk. This development has in turn increased the need of robots with more human-awareness. Therefore, this master thesis aims at contributing to the enhancement of human-aware robotics. Specifically, we are investigating the possibilities of equipping autonomous robots with the capability of assessing and detecting activities in human teams. This capability could, for instance, be used in the robot's reasoning and planning components to create better plans that ultimately would result in improved human-robot teamwork performance. we propose to improve existing teamwork activity recognizers by adding intangible features, such as stress, motivation and focus, originating from human behavior models. Hidden markov models have earlier been proven very efficient for activity recognition and have therefore been utilized in this work as a method for classification of behaviors. In order for a robot to provide effective assistance to a human team it must not only consider spatio-temporal parameters for team members but also the psychological.To assess psychological parameters this master thesis suggests to use the body signals of team members. Body signals such as heart rate and skin conductance. Combined with the body signals we investigate the possibility of using System Dynamics models to interpret the current psychological states of the human team members, thus enhancing the human-awareness of a robot.Användningen av autonoma robotar i vårt samhälle ökar varje dag och en robot ses inte längre som ett verktyg utan som en gruppmedlem. Robotarna arbetar nu sida vid sida med oss och ger oss stöd under farliga arbeten där människor annars är utsatta för risker. Denna utveckling har i sin tur ökat behovet av robotar med mer människo-medvetenhet. Därför är målet med detta examensarbete att bidra till en stärkt människo-medvetenhet hos robotar. Specifikt undersöker vi möjligheterna att utrusta autonoma robotar med förmågan att bedöma och upptäcka olika beteenden hos mänskliga lag. Denna förmåga skulle till exempel kunna användas i robotens resonemang och planering för att ta beslut och i sin tur förbättra samarbetet mellan människa och robot. Vi föreslår att förbättra befintliga aktivitetsidentifierare genom att tillföra förmågan att tolka immateriella beteenden hos människan, såsom stress, motivation och fokus. Att kunna urskilja lagaktiviteter inom ett mänskligt lag är grundläggande för en robot som ska vara till stöd för laget. Dolda markovmodeller har tidigare visat sig vara mycket effektiva för just aktivitetsidentifiering och har därför använts i detta arbete. För att en robot ska kunna ha möjlighet att ge ett effektivt stöd till ett mänskligtlag måste den inte bara ta hänsyn till rumsliga parametrar hos lagmedlemmarna utan även de psykologiska. För att tyda psykologiska parametrar hos människor förespråkar denna masteravhandling utnyttjandet av mänskliga kroppssignaler. Signaler så som hjärtfrekvens och hudkonduktans. Kombinerat med kroppenssignalerar påvisar vi möjligheten att använda systemdynamiksmodeller för att tolka immateriella beteenden, vilket i sin tur kan stärka människo-medvetenheten hos en robot.
The thesis work was conducted in Stockholm, Kista at the department of Informatics and Aero System at Swedish Defence Research Agency.
Livres sur le sujet "Sharks Physiology"
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International White Shark Symposium (2010 : Honolulu, Hawaii), dir. Global perspectives on the biology and life history of the white shark. Boca Raton : Taylor & Francis, 2012.
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Sharks and their relatives II : Biodiversity, adaptive physiology, and conservation. Boca Raton, FL : CRC Press/Taylor & Francis, 2010.
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Gilda, Berger, dir. Flies. New York : Scholastic, 2011.
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Simons, Terry. The Baas Becking Geobiological Laboratory field trip to Shark Bay, W.A., July 1986 : Observations and technical notes. Campbell, A.C.T., Australia : Dept. of Geography and Oceanography, University College, University of New South Wales, Australian Defence Force Academy, 1987.
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Bindi, Marco, Giada Brandani, Alessandro Dessì, Camilla Dibari, Roberto Ferrise, Marco Moriondo et Giacomo Trombi, dir. Impact of climate change on agricultural and natural ecosystems. Florence : Firenze University Press, 2009. http://dx.doi.org/10.36253/978-88-8453-921-2.
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This book illustrates the main results deriving from fourteen studies, dealing with the impact of climate change on different agricultural and natural ecosystems, carried out within the Impact of Climate change On agricultural and Natural Ecosystems (ICONE) project funded by the ALFA Programme of the European Commission. During this project, a common methodology on several Global Change-related matters was developed and shared among members of scientific communities coming from Latin America and Europe. In order to facilitate this interdisciplinary approach, specific mobility programmes, addressed to post-graduate, Master and PhD students, have been organized. The research, led by the research groups, was focused on the study of the impact of climate change on various environmental features (i.e. runoff in hydrological basins, soil erosion and moisture, forest canopy, sugarcane crop, land use, drought, precipitation, etc). Integrated and shared methodologies of atmospheric physics, remote sensing, eco-physiology and modelling have been applied.
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Sharks (Nature Watch (Lorenz)). Lorenz Books Childrens, 2000.
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Sharks : Nature Fact File Series. Southwater, 2003.
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Sharks : Killers of the Deep. Gallery Books, 1985.
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C, Carrier Jeffrey, Musick John A et Heithaus Michael R, dir. Sharks and their relatives II : Biodiversity, adaptive physiology, and conservation. Boca Raton : Taylor & Francis, 2010.
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Musick, John A., Michael R. Heithaus et Jeffrey C. Carrier. Sharks and Their Relatives II : Biodiversity, Adaptive Physiology, and Conservation. Taylor & Francis Group, 2010.
Trouver le texte intégralChapitres de livres sur le sujet "Sharks Physiology"
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Simonitis, Lauren Eve, Miasara Andrew, Tatyana Brewer-Tinsley, Aubree Jones, Peyton Thomas, Sabrina Van Eyck et Amani Webber-Schultz. « Fields of elasmobranch anatomy and physiology ». Dans Minorities in Shark Sciences, 71–116. Boca Raton : CRC Press, 2022. http://dx.doi.org/10.1201/9781003260370-3.
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Beyerlein, Peter. « Informational physiology of individual development ». Dans The Routledge International Handbook of Shared Parenting and Best Interest of the Child, 129–41. Abingdon, Oxon ; New York, NY : Routledge, 2021. : Routledge, 2021. http://dx.doi.org/10.4324/9781003140566-12.
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Forrest, John N., et Grant G. Kelley. « Chloride Secretion in the Shark Rectal Gland : A Model for Epithelial Adenosine Receptors ». Dans Adenosine and Adenine Nucleotides : From Molecular Biology to Integrative Physiology, 211–18. Boston, MA : Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-2011-5_25.
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Bouyoucos, Ian A., et Jodie L. Rummer. « Improving ‘shark park’ protections under threat from climate change using the conservation physiology toolbox ». Dans Conservation Physiology, 185–204. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198843610.003.0011.
Texte intégralRésumé :
Sharks and rays are among the most threatened aquatic vertebrate taxa. This is due to a combination of their slow generation times, exploitation within the fisheries, and habitat degradation. Climate change was added as an additional, major threat to sharks and rays in the first decade of the 21st century. While marine protected areas are becoming more widespread, managing and conserving sharks and rays is complicated. Yet, the conservation physiology toolbox can be used to address such challenges. Here, we highlight studies from the Physioshark project, a conservation physiology research programme initiated to understand how human-induced stressors, primarily climate change, will affect tropical sharks and rays and the consequences for the health and viability of populations. We also highlight how other research teams from around the world have taken physiological approaches to understanding conservation problems for sharks. We then emphasize the importance of public outreach and education about the conservation issues sharks encounter, the benefits of using social media to disseminate key concepts, publications, presentations, media, and successes, and we underscore the power of storytelling through digital media as an important means for attracting attention to research, which can result in support and action.
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« Hormonal Regulation of Elasmobranch Physiology ». Dans Biology of Sharks and Their Relatives, 329–64. CRC Press, 2012. http://dx.doi.org/10.1201/b11867-19.
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Ballantyne, J. S., et J. W. Robinson. « CHONDRICHTHYES | Physiology of Sharks, Skates, and Rays ». Dans Encyclopedia of Fish Physiology, 1807–18. Elsevier, 2011. http://dx.doi.org/10.1016/b978-0-12-374553-8.00043-5.
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« Sensory Physiology and Behavior of Elasmobranchs ». Dans Biology of Sharks and Their Relatives, 365–418. CRC Press, 2012. http://dx.doi.org/10.1201/b11867-20.
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Block, B. A. « PELAGIC FISHES | Endothermy in Tunas, Billfishes, and Sharks ». Dans Encyclopedia of Fish Physiology, 1914–20. Elsevier, 2011. http://dx.doi.org/10.1016/b978-0-12-374553-8.00103-9.
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« Biology and Management of Dogfish Sharks ». Dans Biology and Management of Dogfish Sharks, sous la direction de John W. Mandelman et Marianne A. Farrington. American Fisheries Society, 2009. http://dx.doi.org/10.47886/9781934874073.ch20.
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Abstract.—To provide a synthesis of the physiological responses to otter-trawl capture in spiny dogfish <em>Squalus acanthias</em>, blood values from trawled individuals were evaluated against values from minimally stressed dogfish caught rapidly by hook and line (control). Values and analyses from published studies are considered along with those from the most expansive set of blood samples taken from dogfish captured by both methods to date. Significant impacts of trawling on dogfish blood physiology were reflected in all parameters excluding log plasma protein. Parameters for whole-blood acid–base status (pH, significant decrease; pO<sub>2</sub>, 45% decrease; pCO<sub>2</sub>, 82% increase), and the metabolite lactate anion (125% increase) were most perturbed relative to differences induced by the capture methods in other parameters. The concentrations of sera monovalent electrolytes (Na<sup>+</sup>, K<sup>+</sup>, Cl<sup>-</sup>) and glucose were significantly elevated by trawling, but not to the magnitude seen in other studies related to capture stress in fish. Significant elevations in hematocrit and reductions in blood urea nitrogen (BUN) concentrations were also observed subsequent to trawling. Overall, this capture method incited marked changes in blood physiology relative to values in minimally stressed dogfish. However, previous studies demonstrating high rates of posttrawl dogfish survival indicate that such changes are resolvable in this species prior to lethal consequences.
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« Integrative Multisensor Tagging : Emerging Techniques to Link Elasmobranch Behavior, Physiology, and Ecology ». Dans Biology of Sharks and Their Relatives, 281–306. CRC Press, 2012. http://dx.doi.org/10.1201/b11867-17.
Texte intégralActes de conférences sur le sujet "Sharks Physiology"
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Potkonjak, Veljko, Vladimir Petrović, Kosta Jovanović et Dragan Kostić. « Human-Robot Analogy − How Physiology Shapes Human and Robot Motion ». Dans European Conference on Artificial Life 2013. MIT Press, 2013. http://dx.doi.org/10.7551/978-0-262-31709-2-ch021.
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Fukushima, Shuichiro, Kenichiro Inagi, Kotaro Oka et Kazuo Tanishita. « Measurement of Micro Flow Field Over Model Endothelial Cells ». Dans ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0228.
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Abstract Shear stress induced by blood flow on the arterial wall affect morphology and physiology of endothelial cells. The specific mechanisms alternating shapes and functions have not been identified in endothelial cells, because of the lack of a detailed description of the flow near the cell surface. Although the velocity profiles were numerically calculated (Barbee et al., 1995, Satcher et al., 1992, Yamamoto et al., 1996), experimental verification has not been accomplished.
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Будак, Александр. « Влияние пониженных температур на прорастание семян сои ». Dans VIIth International Scientific Conference “Genetics, Physiology and Plant Breeding”. Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2021. http://dx.doi.org/10.53040/gppb7.2021.30.
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The urgency of soybean breeding for increasing resistance to low temperatures is caused by a large share of the arid regions of Moldova, where the increase in productivity can be ensured by carrier earlier plant-ing and ripening periods before the summer droughts peaks. Thus, as a result of the studies carried out, it was found that when germinating seeds at a temperature of 4˚C, selection is stricter and more efficient. Sowing in the early stages is possible, since soybean seeds remain viable at low temperatures, and when the temperature rises, the best varieties reach the germination rate characteristic of optimal conditions.
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Fukushima, Shuichiro, Ai Nagatsu, Makoto Kaibara, Kotaro Oka et Kazuo Tanishita. « Wall Shear Stress Distribution on the Surface of Realistic Endothelial Cell Model ». Dans ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0366.
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Abstract Wall shear stress induced by blood flow affects morphology and physiology of endothelial cells. The specific mechanisms of mechano-biological interactions alternating shapes and functions have not been identified in the cells, because of the lack of a detailed description of microscopic flow near the cell surface. We therefore developed velocimetry using expanded cell model and demonstrated that the microscopic flow depended on three-dimensional cell shape (Fukushima et al., 1997, 1998). Furthermore, we determined wall shear stress distribution on cultured endothelial cells experimentally.
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Fukushima, Shuichiro, Takaaki Deguchi, Masahiro Nishida, Makoto Kaibara, Kotaro Oka et Kazuo Tanishita. « Determination of Microscopic Wall Shear Stress Distribution on Endothelial Cell Model ». Dans ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0054.
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Abstract Wall shear stress induced by blood flow affects morphology and physiology of endothelial cells. The specific mechanisms alternating shapes and functions have not been identified in endothelial cells, because of the lack of a detailed description of the flow near the cell surface. To clarify the mechanism, an analysis of the flow on subcellular scale is required. We therefore developed velocimetry using expanded cell model (Fukushima et al. 1997). The method, however, needs some improvements in order to discuss wall shear stress distribution on subcellular scale. In this paper we deal with determination of three-dimensional velocity field and wall shear stress distribution and verify the reliability by comparing experimental results with theoretical solution.
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Бобровский, А. А. « On the Method of Study Vessels’ Shapes From Archeological Excavations ». Dans ФОРМЫ ГЛИНЯНЫХ СОСУДОВ КАК ОБЪЕКТ ИЗУЧЕНИЯ. Crossref, 2018. http://dx.doi.org/10.25681/iaras.2018.978-5-94375-254-4.11-25.
Texte intégralRésumé :
he author puts forward an original procedure of earthenware shapes study. Presentment of the procedure is prefaced by a big review of procedures and methods of analytical study of vessel shapes that exist in the Russian and foreign science. Along with the review principal methods are not just described but efficiency of these methods is analyzed. In result, the author concludes that, within analytical approach to earthenware shapes study, rather stable opinions on the prospects of vessels and their separate parts comparison with geometrical bodies emerged. The common characteristic of all these methods is the approach to vessel shapes study from positions of formal analysis. The procedure put forward by the author is based on perception of vessel shapes as the materialized result of a certain system of a potter’s physical efforts (compression, extension and lifting of clay during pottery making) distribution. Analysis of this system of a potter’s physical efforts distribution allows distinguishing the natural earthenware shapes structure. Places where a potter applied the particular force are marked with points of the greatest local flexure. These points represent borders of functional parts of a vessel consisting of functional parts. Since all earthenware vessels have some asymmetry, methods of this asymmetry elimination by way of the average contour of a vessel drawing are specially discussed in the article. The suggested procedure of vessel shapes analysis differs from all earlier ones because it considers vessels not as certain geometry creations but as materialized results produced by labor physiology of particular potters’ labor. The author holds that procedures and methods of vessels production study as a peculiar source of historical information should rest on this informal ground.
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Serna-Garcia, Marta, Eva Serna, María Dolores Mauricio, Teresa San-Miguel, Javier Megías et Nicla Flacco. « Valoración de diferentes perfiles de alumnado sobre material multimedia en asignaturas básicas de Ciencias de la Salud ». Dans IN-RED 2022 : VIII Congreso de Innovación Educativa y Docencia en Red. València : Editorial Universitat Politècnica de València, 2022. http://dx.doi.org/10.4995/inred2022.2022.15881.
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Two of the pillars on which university education is based are the integrated curriculum and transdisciplinarity. The first consists of combining and teaching two or more subjects together, while the second refers to interacting and working as a team with professionals from other areas, to have a 360º vision. This work is the result of a collaboration between teachers from different universities and departments in the area of Health Sciences, who implemented a multimedia material integrating contents of Biology and Physiology, with the aim of promoting the achievement of a more significant knowledge in students.The multimedia material consisted of an explanatory video on the transport through the membrane, which was produced at the Universitat de València (UV) and later implemented at another university with a different student profile, the Universidad Europea de Valencia (UEV). The student assessment surveys showed a good acceptance by this type of student, in the same way that was obtained in the previous study at the UV.This work supports the use of multimedia materials in university teaching to integrate content between subjects. In addition, it motivates teachers to continue making similar materials that can be shared between different institutions so that the work is more effective, useful and productive, and improves the quality of teaching.
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Manning, Keefe B., et Gerald E. Miller. « Shaft/Shaft-Seal Interaction of a Multiple Disk Centrifugal Blood Pump : A Study of Thermal and Wear Characteristics ». Dans ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0197.
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Abstract A multiple disk centrifugal pump (MDCP) is under investigation as a potential left ventricular assist device. As is the case with most shaft driven pumps, leakage problems around the shaft/shaft-seal interface are of major interest. If leakage were to occur during or after implantation, potential events such as blood loss, clotting, blood damage, and/or infections might result in adverse effects for the patient. Because these effects could be quite disastrous, potential shaft and shaft-seal materials have been investigated to determine the most appropriate course to limit these effects. Teflon and Nylon were analyzed as potential shaft-seal candidates with both a stainless steel shaft and a Melonite® coated shaft, the latter provided by Houston Unlimited Inc. Metal Processing in Chappell Hill, Texas. The materials and shafts were evaluated under time, motor, and outer diameters. Motor speed and geometrical configurations were typical for the MDCP under normal physiologic conditions. The three parameters analyzed were the inner diameter (ID), the inner temperature, and the outer temperature. Statistical comparisons were computed for the shaft seal materials, the shafts, and the outer diameters along with the inner and outer temperatures.
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Amirouche, Farid, Mark Gonzalez, Wayne Goldstein, Adam Derhake, Barbara Dudas et Madhuri Tanushri. « Computer Modeling of the Patellofemoral Joint Instability : Patella Inherent Geometry Influence on Stress and Loading ». Dans ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206885.
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Despite a large range of surgical options, treatment of patellofemoral instability continues to be a challenging clinical problem. Currently, there have been a number of computer models developed to try and better define the stabilizing forces about the patellofemoral joint. However, most of these studies have focused on patellofemoral contact pressures, omitting evaluation of patellar stability in the first 30° of knee flexion. The purpose of this study was to reconstruct a pathologic and normative patellar shape within a computer model based on previously described morphologic ratios. We then applied physiologic force vectors to each patellar shape and calculated the stress and moment about each. We hypothesized that individuals with a pathologic patellar shape would have internal stress and moments about the patella which could predispose them to instability. We found that there were significant differences in patterns of stress, strain, and internal displacement about the control and study patellar shapes. This study suggests that a change of patellar shape could have significant effects on the stresses and moments about the patella. Future studies in which calculations of moments could be performed on a series of control and study patellar groups could further define this difference. Dynamic simulations of the control and study patellar shapes could also visually demonstrate the difference in patellar translation. In the future, the results of patellofemoral modeling could be applied to individual patients to more accurately detail an individual treatment plan.
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Thuramalla, Naveen V., William I. Douglas, Prem Rachakonda, Jamey D. Jacob et Charles F. Knapp. « Effect of Plunger Design on the Constricting Forces in an Adjustable Systemic to Pulmonary Artery Shunt ». Dans ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61127.
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Hypoplastic left heart syndrome (HLHS) is a leading cause of cardiac death among newborns, in which the entire left side of the heart is underdeveloped and unable to support the blood circulation. It is the most common type of single ventricle physiology (SVP) and an important need for an adjustable systemic to pulmonary artery (SPA) shunt. In order to achieve full range control of blood flow between the systemic and pulmonary circulation, an adjustable SPA shunt is being developed. SPA shunts are generally made from FDA approved polytetrafluroethylene (PTFE). A screw-plunger mechanism is being used to cause the desired constriction in the pressurized shunt. It is necessary to optimize the design of the plunger, in order to vary the cross-section of the shunt with minimum forces required. An in vitro set up consisting of a hydraulic circuit to have a constant inlet pressure to the shunt throughout the process and a certain post shunt pressure initially, plunger attached to the force gauge mounted on a stand to cause constriction and measure forces, a mounting stand to hold the shunt and its casing, a flow meter and pressure transducers, is used to determine the effect of various plunger tip shapes. It was observed that wider the plunger, lesser is the force required to cause the same reduction in flow. Flow-displacement-force variations for each plunger tip used are also presented. Results from this study will be used to determine the torque required to drive the screw plunger mechanism to cause the desired constriction.
Rapports d'organisations sur le sujet "Sharks Physiology"
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Fridman, Eyal, et Eran Pichersky. Tomato Natural Insecticides : Elucidation of the Complex Pathway of Methylketone Biosynthesis. United States Department of Agriculture, décembre 2009. http://dx.doi.org/10.32747/2009.7696543.bard.
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Plant species synthesize a multitude of specialized compounds 10 help ward off pests. and these in turn may well serve as an alternative to synthetic pesticides to reduce environmental damage and health risks to humans. The general goal of this research was to perform a genetic and biochemical dissection of the natural-insecticides methylketone pathway that is specific to the glandular trichomes of the wild species of tomato, Solanumhabrochaites f. glabratum (accession PI126449). Previous study conducted by us have demonstrated that these compounds are synthesized de novo as a derivate pathway of the fatty acid biosynthesis, and that a key enzyme. designated MethylketoneSynthase 1 (MKS 1). catalyzes conversion of the intermediate B-ketoacyl- ACPs to the corresponding Cn-1 methylketones. The approach taken in this proposed project was to use an interspecific F2 population. derived from the cross between the cultivated lV182 and the wild species PIl26449. for three objectives: (i) Analyze the association between allelic status of candidate genes from the fatty acid biosynthesis pathway with the methylketone content in the leaves (ii) Perform bulk segregant analysis of genetic markers along the tomato genome for identifying genomic regions that harbor QTLs for 2TD content (iii) Apply differential gene expression analysis using the isolated glands of bulk segregant for identifying new genes that are involved in the pathway. The genetic mapping in the interspecific F2 population included app. 60 genetic markers, including the candidate genes from the FAS pathway and SSR markers spread evenly across the genome. This initial; screening identified 5 loci associated with MK content including the candidate genes MKS1, ACC and MaCoA:ACP trans. Interesting observation in this genetic analysis was the connection between shape and content of the glands, i.e. the globularity of the four cells, typical to the wild species. was associated with increased MK in the segregating population. In the next step of the research transcriptomic analysis of trichomes from high- and 10w-MK plants was conducted. This analysis identified a new gene, Methy1ketone synthase 2 (MKS2), whose protein product share sequence similarity to the thioesterase super family of hot-dog enzymes. Genetic analysis in the segregating population confirmed its association with MK content, as well as its overexpression in E. coli that led to formation of MK in the media. There are several conclusions drawn from this research project: (i) the genetic control of MK accumulation in the trichomes is composed of biochemical components in the FAS pathway and its vicinity (MKS 1 and MKS2). as well as genetic factors that mediate the morphology of these specialized cells. (ii) the biochemical pathway is now realized different from what was hypothesized before with MKS2 working upstream to I\1KS 1 and serves as the interface between primary (fatty acids) and secondary (MK) metabolism. We are currently testing the possible physical interactions between these two proteins in vitro after the genetic analysis showed clear epistatic interactions. (iii) the regulation of the pathway that lead to specialized metabolism in the wild species is largely mediated by transcription and one of the achievements of this project is that we were able to isolate and verify the specificity of the MKS1 promoter to the trichomes which allows manipulation of the pathways in these cells (currently in progress). The scientific implications of this research project is the advancement in our knowledge of hitherto unknown biochemical pathway in plants and new leads for studying a new family in plants (hot dog thioesterase). The agricultural and biotechnological implication are : (i) generation of new genetic markers that could assist in importing this pathway to cultivated tomato hence enhancing its natural resistance to insecticides, (ii) the discovery of MKS2 adds a new gene for genetic engineering of plants for making new fatty acid derived compounds. This could be assisted with the use of the isolated and verified MKS1 promoter. The results of this research were summarized to a manuscript that was published in Plant Physiology (cover paper). to a chapter in a proceeding book. and one patent was submitted in the US.