975 research outputs found
FROM ORGANISMS TO ECOSYSTEMS: IMPACTS OF LIMB LOSS AND REGENERATION ON CRAYFISH BEHAVIOR
The ability of some organisms to regenerate tissues and organs has fascinated naturalists since antiquity, dating back to the earliest accounts of scientific inquiry with Aristotle in Ancient Greece. Then, Darwinâs theory invigorated some scientistsâ dream of stimulating (or reactivating) regenerative capacities in human beings by showing that we are related to highly regenerative organisms. More recently, a renewed interest in discovering the molecular and genetic basis for organ and tissue regeneration has led biologists to focus more specifically on a restrictive set of model organisms.
Although the process of limb regeneration is different between invertebrate and vertebrate organisms, it follows the same general principles and steps. The presence or absence of regenerative ability appears to broadly correlate with the incidence of autotomy (reflex severance of a limb). Autotomy allows individuals to reduce costs associated with damaged structures, often limbs, by severing the appendage at a predetermined breakage plane, thus limiting wounding and helping the regeneration process. Individuals capable of rebuilding damaged structures during their lifespan may have higher fitness than individuals without this. This may help to explain how selective pressures for regenerative capacities could be maintained or acquired. The regenerative process, induced by autotomy, may also have high physiological costs and this comes with its own set of challenges in turn affecting how regenerating individuals interact with and change their environment.
Organisms capable of regeneration can also have impacts on their environment through their behavior. Therefore, regeneration of structures important for behavioral effects on the environment can mediate organismsâ environmental impacts. Recently, these reciprocal impacts have been the focus of new theory conceptualizing the ecological implications of organismal habitat, namely, ecosystem engineering (defined as the process by which organisms modify their physical environment from one physical state to another).
Furthermore, regeneration creates periods of time during which regenerating organisms face newfound challenges mediated by the way those organisms interact with their environments. Once again, regenerating crayfish might not be able to dig a burrow when needed (during drought, reproduction, etc.). Thus, they could find themselves competing for existing burrows or facing a now necessary migration to find water all of which non-regenerating crayfish may not experience. Therefore, ecosystem engineers capable of regeneration represent a powerful system allowing us to develop a clearer understanding of how regeneration might evolve as well as persist through its effects on organismal fitness
Epigenetic control of tissue-type plasminogen activator synthesis in human endothelial cells
Aims Tissue-type plasminogen activator (t-PA) is produced by endothelial cells (EC) and is responsible for the removal of intravascular fibrin deposits. We investigated whether expression of t-PA by EC is under epigenetic control. Methods and results Methylation analysis of the proximal t-PA promoter revealed a stretch of unmethylated CpG dinucleotides from position â121 to +59, while upstream CpG dinucleotides were all methylated. In contrast, in human primary hepatocytes, which express t-PA at much lower levels than EC, the proximal promoter was partially methylated. Treatment of EC with the non-specific histone deacetylase (HDAC) inhibitors butyrate and trichostatin and with MS275, a specific inhibitor of class I HDAC, resulted in a time- and dose-dependent increase in t-PA expression. Garcinol and anacardic acid, inhibitors of the histone acetyl transferases CBP/p300 and PCAF, reduced basal and HDAC inhibitor-induced t-PA expression, whereas curcumin, an inhibitor of CBP/p300 only, had no effect. We performed chromosome immunoprecipitation analysis of the t-PA promoter using antibodies specific for acetylated histone H3 or H4 and observed an increase in H3 acetylation of 10 ± 3 and 44 ± 14-fold in EC treated with trichostatin or MS275, respectively, and in H4 acetylation of 7.7 ± 1.4 and 16 ± 3-fold, respectively. Conclusion The proximal t-PA promoter is unmethylated in human EC and partially methylated in human primary hepatocytes. Expression of t-PA by EC is repressed by HDACs in a mechanism that involves de-acetylation of histone H3 and H
Le processus de patrimonialisation dâun petit fromage de montagne, le persillĂ© de Tarentaise
La Tarentaise est une longue vallĂ©e intra-alpine appartenant au dĂ©partement de la Savoie. Terre de contrastes, elle rĂ©unit en son sein une grande variĂ©tĂ© de paysages et de micro-terroirs, mais Ă©galement de rĂ©alitĂ©s sociologiques, avec des zones agricoles qui cĂŽtoient les plus grands domaines skiables du monde. Dans le secteur haut de la vallĂ©e, quelques Ă©leveurs de chĂšvres ont organisĂ© leur production autour dâun petit fromage local, le persillĂ©, dont ils disent avoir hĂ©ritĂ© les procĂ©dĂ©s de fabrication de leurs parents et grands-parents. Les donnĂ©es collectĂ©es dans le cadre dâune enquĂȘte anthropologique sur les pratiques culinaires et alimentaires en Tarentaise, commandĂ©e par le MusĂ©e savoisien (ChambĂ©ry) entre janvier 2018 et janvier 2019, permettent dâinterprĂ©ter le contexte dans lequel se situe ce fromage : aprĂšs avoir connu un certain dĂ©clin, Ă lâombre du prestigieux beaufort, il est actuellement en reprise en raison de lâengouement des consommateurs contemporains pour les produits locaux non industriels. Lâarticle entend illustrer les enjeux existant autour de lâĂ©mergence dâun objet patrimonial, Ă travers la description et lâanalyse de la variĂ©tĂ© des productions portant le mĂȘme nom (sur lâaxe diachronique aussi bien que sur lâaxe synchronique), ainsi que des tensions existant entre les diffĂ©rents producteurs, chacun revendiquant un statut particulier au sein de la triade « producteur â persillĂ© â territoire ».The Tarentaise is a long alpine valley located in the department of Savoie. It is a land of contrasts, with a wide variety of landscapes and micro-terroirs, specific localities with specific products, but also many different sociological realities. Agricultural zones coexist with the largest skiing domains in the world. In the upper part of the valley, some goat farmers have organised their production around a local blue veined cheese, the persillĂ©, of which they claim to have inherited the manufacturing processes from their parents and grandparents. Information collected during an anthropological study on culinary and food practices in the Tarentaise, commissioned by the MusĂ©e savoisien (ChambĂ©ry) between January 2018 and January 2019, make it possible here to give an account of the context in which this cheese evolved. After a certain decline, when the persillĂ© was overshadowed by the prestigious Beaufort cheese, its new success was founded on the appeal that non-industrial local products exercises over consumers today. The article aims to illustrate the issues surrounding the revival of this cheese. It describes and analyses the variety of cheese products bearing the same name (on the diachronic level as well as on a synchronic one) and looks at the tensions between the different producers, each one claiming a special status within the triad formed by the producer, the persillĂ© and the territory
Risk and animal welfare, the role of the Anses
As part of the new animal welfare governance, Anses was asked to organize the risk assessment expertise.
Its new Working Group for Animal Welfare is responsible for providing available scientific elements
on various animal welfare issues to risk managers, for decision making. The organization of
collective expertise at Anses is presented here, emphasizing the qualities of independence and transparency
of the collegial and multidisciplinary work of expertise. The Working Group for Animal Welfare,
created at the end of 2012, gave himself a double mandate : build his own fundamental basis for expertise
about animal welfare, and address the different questions, today mainly received from the authorities.
Questions may also arise from stakeholders represented on its board or self- mandate from the
Agency itself. In terms of animal welfare, Anses can also use the results of research conducted within
some of its laboratoriesDans le cadre de la nouvelle gouvernance mise en place dans le domaine de la protection animale,
lâAnses sâest vu confier lâactivitĂ© dâĂ©valuation des risques. Son nouveau Groupe de Travail Bien-ĂȘtre
des animaux est chargé de fournir aux gestionnaires des risques les éléments scientifiques disponibles
sur diffĂ©rentes questions de protection animale, en amont de leurs dĂ©cisions. Lâorganisation de lâexpertise
collective Ă lâAnses est ici prĂ©sentĂ©e, en soulignant le caractĂšre collĂ©gial, multidisciplinaire,
indĂ©pendant et transparent qui prĂ©side aux travaux dâexpertise. Le Groupe de Travail Bien-ĂȘtre des
animaux, constitué fin 2012, mÚne de front la construction de ses propres fondamentaux et la réponse
aux diffĂ©rentes saisines, principalement reçues aujourdâhui des autoritĂ©s. Des questions peuvent Ă©galement
provenir de parties prenantes reprĂ©sentĂ©es Ă son conseil dâadministration ou dâauto-saisines
de lâAgence elle-mĂȘme. En matiĂšre de bien-ĂȘtre des animaux, lâAnses bĂ©nĂ©ficie Ă©galement des fruits
des activités de recherche menée au sein de certains de ses laboratoire
Current regulation applicable to ritual slaughter
EU and national regulations do not include definitions or specifications of religious slaughter, whether
Halal or Kosher. The question of religious slaughter is addressed mainly in the form of derogations
from the general provisions, such as exempting pre-cut stunning, and allowing the section of esophagus
and trachea during bleeding. The restraint of animals slaughtered ritually must be strengthened
during bleeding, and the operators involved must be properly trained for it. In France as in numerous
States, religious slaughter can be a highly controversial topic which regulation alone cannot solve.
Ritual slaughter is first and foremost a religious action that must comply with the rules and good practices
of animal welfare and hygienic handling. The religious background of ritual slaughter must not
be used as a pretext or alibi for non-compliance with the statutory requirements, which is unfortunately
sometimes the case. Religious requirements and statutory regulations are perfectly compatible,
and may even enhance each other when they are met. Current regulations applicable to animal
slaughter and welfare seem satisfactory; some points should however be clarified, particularly those
relating to derogations from the provisions on prior stunning. The strict application of regulations
combined with training and information of the various actors will help meet the fundamental objectives
in animal welfare and hygienic handling, reduce non-compliances, enhance good practices, and
hence reduce the tensions surrounding ritual slaughter practices.Les réglementations
communautaire et nationale ne contiennent pas de définition ni de spécification pour
l'abattage rituel, qu'il soit halal ou casher. Ces textes intĂšgrent la question de
l'abattage rituel essentiellement sous la forme de dérogations aux prescriptions générales.
D'une part, ils permettent de déroger à l'étourdissement préalable avant la saignée et
d'autre part, ils permettent la section de l'oesophage et de la trachée des animaux lors de
la saignĂ©e. Les modalitĂ©s de contention des animaux abattus rituellement doivent ĂȘtre
renforcées lors de la saignée, et les personnes réalisant la mise à mort des animaux doivent
ĂȘtre habilitĂ©es pour cet acte. En France comme dans de nombreux Ătats, la pratique de
l'abattage rituel fait souvent l'objet de dĂ©bats qui peuvent ĂȘtre trĂšs polĂ©miques, car cet
acte fait intervenir de nombreuses composantes et sensibilités et la réglementation seule ne
saurait prétendre à résoudre toutes les problématiques. L'abattage rituel est avant tout un
acte religieux qui doit intégrer les rÚgles et bonnes pratiques en matiÚre de protection des
animaux et d'hygiĂšne des manipulations. Le cadre religieux de l'abattage rituel ne doit pas
servir de prétexte ou d'alibi au non-respect des exigences réglementaires, ce qui est
malheureusement parfois constaté. Exigences religieuses et réglementation sont parfaitement
compatibles, voire se potentialisent réciproquement lorsqu'elles sont satisfaites. Les
réglementations existantes applicables en matiÚre de modalités d'abattage et de
bientraitance apparaissent satisfaisantes; certains points mĂ©riteraient nĂ©anmoins d'ĂȘtre
précisés, en particulier ceux relatifs aux modalités de dérogation à l'étourdissement. La
stricte application des réglementations, associée à des formations et informations destinées
aux différents acteurs, tout en permettant d'atteindre les objectifs fondamentaux en matiÚre
de protection animale et d'hygiĂšne des manipulations, devrait permettre de faire diminuer
les non-conformités, d'améliorer les bonnes pratiques et en conséquence, de tendre vers un
apaisement des tensions entourant la pratique de l'abattage rituel
De la magie des sons Ă la magie du monde
NĂ©e Ă Aoste le 16 juillet 1972 de parents valdĂŽtains, elle a grandi, et vit toujours dans cette rĂ©gion oĂč la variation linguistique est une expĂ©rience quotidienne. Sensible Ă tout ce qui a trait Ă la communication, elle partage ici ses souvenirs autour des nombreuses langues avec lesquelles elle est entrĂ©e en contact. Anthropologue, elle porte un regard dĂ©calĂ© sur son expĂ©rience personnelle, mais au fil de ces pages elle tente de restituer un tĂ©moignage aussi vrai que possible.Born in Aosta July 16, 1972 of Valdaostan parents, she grew up and still lives in this region, where linguistic variation is a day-to-day experience. Awake to everything that concerns communication, she shares with us her memories of the many languages with which she came into contact. As an anthropologist, she casts an objective eye upon her own life expĂ©rience, but tries to deliver, as she goes along, an as authentically personal account as possible
ComparaciĂłn de fuerzas de corte del escalpelo y profundidad en tejidos gingivales porcinos
The composition of the gums confers some physical characteristics that make it resistant to mechanical stimulation. The objective of the study was to compare the difference of the utilized forces when performing cuts in the anterior and posterior sections of porcine gingival tissue, measuring the depth of the tissue. A comparative descriptive study was performed with a non-probability convenience sampling, sectioned pig mandibles were used. The experimental trials were performed with an EZ-S SHIMADZU texture analyzer. All of the samples were submitted to a vertical shear force, thus identified the force level used to perform the incision and its depth. the necessary force to perform a cut in porcine gingival tissue was evaluated, comparing the posterior section (39.3571 Newton and 2.160 mm) and with the anterior ( 37.8424 newton and 1.747 mm), just as the depth of said cut, showing a statistical difference on the depth, (p=0.022 p< 0.59); regarding the force, no statistically significant difference was found. In the analyzed samples where the shear force in the posterior and anterior section were compared, no difference was found in both groups; as for the cut depth, this was greater in the posterior section than in the anterior.La composiciĂłn de las encĂas le confiere algunas caracterĂsticas fĂsicas que la hacen resistentes al estĂmulo mecĂĄnico. El objetivo del estudio fue comparar la diferencia de fuerzas utilizadas al realizar cortes en las secciones anterior y posterior del tejido gingival porcino, midiendo la profundidad del tejido. Se realizĂł un estudio descriptivo comparativo con un muestreo de conveniencia no probabilĂstico, se utilizaron mandĂbulas de cerdo seccionadas. Los ensayos experimentales se realizaron en un analizador de textura EZ-S SHIMADZU. Todas las muestras se sometieron a una fuerza de corte vertical, por lo que se identificĂł el nivel de fuerza utilizado para realizar la incisiĂłn y su profundidad. Se evaluĂł la fuerza necesaria para realizar un corte en el tejido gingival porcino, comparando la secciĂłn posterior con la anterior, al igual que la profundidad de dicho corte, mostrando una diferencia estadĂstica en la profundidad (p = 0,022 p <0,59). Con respecto a la fuerza, no se encontraron diferencias estadĂsticamente significativas. En las muestras analizadas donde se comparĂł la fuerza de corte en la secciĂłn posterior y anterior, no se encontraron diferencias en ambos grupos; en cuanto a la profundidad de corte, esta fue mayor en la secciĂłn posterior que en la anterior
Antiformalismo y la escuela del derecho libre en Colombia
La forma de estudiar y entender el derecho y los sistemas jurĂdicos han ido evolucionado con el paso del tiempo, predominaba en un inicio los pensamientos liderados por los positivistas formalista, y como antĂtesis surge las corrientes antiformalistas del derecho, y es entonces donde surge la escuela libre del derecho, el Realismo jurĂdico y la escuela del derecho libre. Por medio de este trabajo investigativo se hablarĂĄ del paradigma formalista y anti-formalista haciendo un especial Ă©nfasis en la escuela libre del derecho, y la influencia de la misma en el ordenamiento jurĂdico colombiano
Gene conversion limits divergence of mammalian TLR1 and TLR6
<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLR) recognize pathogen-associated molecular patterns and are important mediators of the innate immune system. TLR1 and TLR6 are paralogs and located in tandem on the same chromosome in mammals. They form heterodimers with TLR2 and bind lipopeptide components of gram-positive and gram-negative bacterial cell walls. To identify conserved stretches in TLR1 and TLR6, that may be important for their function, we compared their protein sequences in nine mammalian species(<it>Homo sapiens</it>, <it>Pan troglodytes</it>, <it>Macaca mulatta</it>, <it>Mus musculus</it>, <it>Rattus norvegicus</it>; <it>Erinaceus europaeus</it>, <it>Bos Taurus</it>, <it>Sus scrofa </it>and <it>Canis familiaris</it>).</p> <p>Results</p> <p>The N-terminal sequences of the orthologous proteins showed greater similarity than corresponding paralog sequences. However, we identified a region of 300 amino acids towards the C-terminus of TLR1 and TLR6, where paralogs had a greater degree of sequence identity than orthologs. Preservation of DNA sequence identity of paralogs in this region was observed in all nine mammalian species investigated, and is due to independent gene conversion events. The regions having undergone gene conversion in each species are almost identical and encode the leucine-rich repeat motifs 16 to 19, the C-terminal cap motif, the transmembrane domain and most of the intracellular Toll/interleukin-1 receptor (TIR) domain.</p> <p>Conclusion</p> <p>Our results show that, for a specific conserved region, divergence of TLR1 and TLR6 is limited by gene conversion, most likely because of the need for co-evolution with multiple intracellular and extracellular binding partners. Thus, gene conversion provides a mechanism for limiting the divergence of functional regions of protein paralogs, while allowing other domains to evolve diversified functions.</p
The protein kinase TOUSLED facilitates RNAi in Arabidopsis
RNA silencing is an evolutionarily conserved mechanism triggered by double-stranded RNA that is processed into 21- to 24-nt small interfering (si)RNA or micro (mi)RNA by RNaseIII-like enzymes called Dicers. Gene regulations by RNA silencing have fundamental implications in a large number of biological processes that include antiviral defense, maintenance of genome integrity and the orchestration of cell fates. Although most generic or core components of the various plant small RNA pathways have been likely identified over the past 15 years, factors involved in RNAi regulation through post-translational modifications are just starting to emerge, mostly through forward genetic studies. A genetic screen designed to identify factors required for RNAi in Arabidopsis identified the serine/threonine protein kinase, TOUSLED (TSL). Mutations in TSL affect exogenous and virus-derived siRNA activity in a manner dependent upon its kinase activity. By contrast, despite their pleiotropic developmental phenotype, tsl mutants show no defect in biogenesis or activity of miRNA or endogenous trans-acting siRNA. These data suggest a possible role for TSL phosphorylation in the specific regulation of exogenous and antiviral RNA silencing in Arabidopsis and identify TSL as an intrinsic regulator of RNA interferenc
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