Increased ROS Production: A Component of the Longevity Equation in the Male Mygalomorph, Brachypelma albopilosa

The diversity of longevities encountered in wildlife is one of the most intriguing problems in biology. Evolutionary biologists have proposed different theories to explain how longevity variability may be driven by bad genes expression in late life or by gene pleiotropic effects. This reflexion has stimulated, in the last ten years, an active research on the proximal mechanisms that can shape lifespan. Reactive oxygen species (ROS), i.e., the by-products of oxidative metabolism, have emerged as the main proximate cause of ageing. Because ROS are mainly produced by the mitochondria, their production is linked to metabolic rate, and this may explain the differences in longevity between large and small species. However, their implication in the sex difference in longevity within a species has never been tested, despite the fact that these differences are widespread in the animal kingdom.Mitochondrial superoxide production of hemolymph immune cells and antioxidant and oxidative damages plasma levels were measured in adult male and female B. albopilosa at different ages. We found that female spiders are producing less mitochondrial superoxide, are better protected against oxidative attack and are then suffering less oxidative damages than males at adulthood.In tarantulas, once reaching sexual maturity, males have a life expectancy reduced to 1 to 2 years, while females can still live for 20 years, in spite of the fact that females continue to grow and moult. This study evidences an increased exposure of males to oxidative stress due to an increase in mitochondrial superoxide production and a decrease in hemolymph antioxidant defences. Such a phenomenon is likely to be part of the explanation for the sharp reduction of longevity accompanying male tarantula maturity. This opens several fundamental research roads in the future to better understand how reproduction and longevity are linked in an original ageing model

A new role for carnitine in yeasts

Thesis (MSc)--University of Stellenbosch, 2006.ENGLISH ABSTRACT: L-Carnitine (3-0H-4-N-trimethylaminobutanoic acid), also called vitamin Br, is required for the metabolism of fatty acids. Only one specific metabolic activity has been ascribed to L-carnitine in eukaryotic organisms, the transfer of activated acyl residues. In the case of yeast, this process involves the transfer of activated acetyl residues from the peroxisomes or the cytoplasm to the mitochondria. In Saccharomyces cerevisiae, 13-oxidation of fatty acids takes place exclusively in the peroxisomes. The process generates peroxisomal acetyl-CoA, and the activated acetyl-residue has to be transferred to the mitochondria for energy production. Acetyl-CoA and other acyl-CoAs however can not be transferred across intracellular membranes. The activated acetyl residue is therefore transferred to a molecule of carnitine to form acetyl carnitine, which can be shuttled across membranes. The reverse reaction, the transfer of the activated acetyl to free CoA-SH and the liberation of carnitine takes place in the mitochondria. This process is also referred to as the carnitine shuttle. Most organisms, including some yeast, fungi, plants and all mammals, but not S. cerevisiae, can synthesize carnitine from lysine and S-adenosyl-methionine. However, in humans, carnitine synthesis is insufficient to satisfy carnitine requirements, and dietary contributions are essential. Various diseases linked to carnitine deficiencies have been described. Such deficiencies include those found in neonates who, in the absence of carnitine, are unable to assimilate fatty acids from milk, or genetically inborn errors of metabolism, frequently linked to a defective transport of carnitine into cells. More recent literature suggests that carnitine supplementation can have beneficial effects in a number of pathologies, and can also provide some protection against diabetes and liver disease. It has furthermore been suggested that carnitine can contribute to slowing brain aging and to improve conditions of patients suffering from neurodegenerative diseases such as Alzheimer's disease. The accumulation of such data may suggest that carnitine plays additional, as yet unrecognized roles in cellular physiology. In the study reported here, the yeast S. cerevisiae was used to identify possible additional roles for carnitine in cellular metabolism. The study furthermore attempted to identify genes that may be associated with such additional roles. The data show that carnitine supplementation of the growth substrate can protect yeast cells from hyper osmotic and high temperature stress. These protective effects are independent of the metabolic role of carnitine, since deletion of genes that are essential for the carnitine shuttle does not reduce the protective effect. The investigation also suggests that there are no other metabolic roles for carnitine in yeast than the carnitine shuttle, and that it therefore may act as a compatible solute in osmo-protection. The data also indicate a role for PH087, previously identified as a low affinity inorganic phosphate carrier, in the protective effect of carnitine. PH087 overexpression strains accumulate higher concentrations of carnitine, whereas pho87t:. strains contain less carnitine than the corresponding wild type strain. The data therefore suggest either a direct or a regulatory role of the protein in carnitine uptake.AFRIKAANSE OPSOMMING: L-Karnitien (3-0H-4-N-trimetielaminobutaansuur), ook bekend as vitamien Br, word vir die metabolisme van vetsure benodig. Tot dusver is net een spesifieke metaboliese aktiwiteit in eukariotiese organismes aan L-karnitien toegeskryf, naamlik die oordrag van geaktiveerde asielreste. In die geval van gis behels hierdie proses die oordrag van geaktiveerde asetielreste vanaf die peroksisome of die sitoplasma na die mitochondria. In Saccharomyces cerevisiae vind die P-oksidasie van vetsure uitsluitlik in die peroksisome plaas. Hierdie proses genereer peroksisomale asetiel-KoA, en die geaktiveerde asetielreste moet vir energieproduksie na die mitochondria oorgeplaas word. Asetiel-KoA en ander asiel-KoA's kan egter nie oar intrasellulere membrane vervoer word nie. Die geaktiveerde asetielreste word dus na 'n karnitienmolekuul oorgedra om asetielkarnitien te vorm, wat oor die membrane vervoer kan word. Die omgekeerde reaksie, naamlik die oordrag van die geaktiveerde asetiel na vrye KoA-SH en die vrystelling van karnitien, vind in die mitochondria plaas. Hierdie proses staan ook as die "karnitien heen-en-weerstelsel" bekend. Die meerderheid organismes, insluitende sommige giste, swamme, plante en alle soogdiere, hoewel nie S. cerevisiae nie, kan karnitien vanaf lisien en S-adenosielmetionien sintetiseer. In mense is karnitiensintese egter onvoldoende om in die karnitienbehoeftes te voorsien en voedingsaanvullings is dus noodsaaklik. Verskeie siektes wat met 'n tekort aan karnitien verband hou, is reeds beskryf. Sulke tekorte kom o.a. voor in pasgebore babas wat in die afwesigheid van karnitien nie die vetsure afkomstig van melk kan opneem nie, of in persone met genetiese afwykings in hul metabolisme wat in baie gevalle met die onvoldoende vervoer van karnitien na die selle verband hou. In onlangse literatuur word daar voorgestel dat karnitienaanvulling voordelig vir 'n aantal patologiese toestande kan wees, en dat dit ook 'n mate van beskerming teen diabetes en lewersiektes kan verskaf. Daar is ook beweer dat karnitien die veroudering van die brein kan teewerk en die toestand van pasiente wat aan neurodegeneratiewe siektes soos Alzheimer's ly, kan verbeter. Hierdie data dui dus op die moontlikheid dat karnitien bykomende, en tot dusver onbekende, funksies in sellulere fisiologie kan he. In die studie waaroor hier verslag gedoen word, is die gis S. cerevisiae gebruik om moontlike bykomende funksies vir karnitien in sellulere metabolisme te identifiseer. Die studie poog om gene wat moontlik met sulke addisionele funksies geassosieer kan word, te identifiseer. Die data toon dat karnitienaanvulling van die groeisubstraat die gisselle teen hiperosmotiese en hoe-temperatuur stres kan beskerm. Hierdie beskermende invloed is onafhanklik van die metaboliese funksie van karnitien, aangesien die delesie van die gene wat noodsaaklik is vir die "karnitien heen-en-weerstelsel" nie die beskermende effek verminder nie. Hierdie ondersoek stel ook voor dat, buiten karnitientransport, daar geen ander metaboliese rolle vir karnitien in gis is nie, en dat dit dus moontlik as 'n verenigbare opgeloste stof in osmo-beskerming kan optree. Die data dui ook op 'n funksie vir PH087, wat voorheen as 'n lae-affiniteit anorganiese fosfaatdraer in die beskermende effek van karnitien ge"identifiseer is. PH087-ooruitdrukkingsrasse akkumuleer hoer karnitienkonsentrasies, terwyl pho87!i-rasse minder karnitien as die ooreenkomstige wilde ras bevat. Die data dui dus op 6f 'n direkte 6f 'n regulatoriese funksie vir die proteren in karnitienopname

Mécanismes physiopathologiques des atteintes musculaires dans les déficits héréditaires en carnitine palmitoyl transférase II

L'oxydation mitochondriale des acides gras à longue chaîne (AGLC) est la principale source d'énergie du cœur et des muscles squelettiques. Les AGLC rentrent dans la mitochondrie par les Carnitine Palmitoyl Transferases (CPT1 et 2) et leur dégradation aboutie à la formation d'acétyl-CoA. Le couplage de la b-oxydation (b-ox) à la chaîne respiratoire assure la production d'ATP avec un rendement énergétique élevé. Les déficits héréditaires de b-ox, regroupent une quinzaine de maladies, souvent associées à une myopathie. Ces pathologies complexes sont bien caractérisées d'un point de vue clinique et génétique mais sont encore mal comprises et peu traitées. Les déficits en CPT2 comptent parmi les déficits les plus fréquents. Ses phénotypes varient d'une forme néonatale sévère, souvent fatale à une forme modérée plus fréquente. Cette myopathie se développe souvent chez l'adolescent et se traduit par des myalgies, une raideur musculaire, une fatigabilité importante, voire des rhabdomyolyses. Ces symptômes sont aggravés par un exercice modéré et des situations de stress métabolique (jeûne, épisode infectieux, froid). L'étude de modèles myoblastes/myotubes de cellules de patients atteints de la forme modérée et exposés à des conditions entrainant l'apparition des symptômes : acides gras et hyperthermie, a permis de mettre en évidence: un stress oxydant, un défaut de prolifération et de différenciation, une chute du potentiel membranaire mitochondrial et un profil apoptose/nécrose différent des témoins. Le bézafibrate, bien que restaurant les capacités de b-oxydation (à 37C), n'a eu quasiment aucun effet bénéfique sur ces paramètres.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Mean superoxide production measured using MitoSOX Red fluorescence intensity levels in haemolymph tarantula cells.

<p>Data were collected during three independent sessions. Rate of superoxide production were standardized among the three sessions of measurement and examined relatively to each mean values. Males (n = 15) presented a relative superoxide production significantly higher than females (n = 14, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013104#pone-0013104-t001" target="_blank">Table 1</a>).</p

General linear model testing the effect of two factors, the time elapsed from the last moult and the residuals between body mass and the time elapsed from the last moult on mitochondrial ROS production in males or females tarantula.

<p>Linear regression values for males were: ROS  = 0.006 x Time from last moult +0.88, r = 0.67. Confidence interval at 95% for the slope value: 0.002–0.009; for the constant: 0.341–1.417.</p

Antioxidant hemolymph barrier measured on male (white cross hatched bars, n = 9) and female (grey cross hatched bars, n = 11) tarantulas, as well as reactive oxygen metabolite levels (5 males (white bars) and 7 females (grey bars)).

<p>Female tarantulas showed a two fold higher antioxidant capacity than males (<i>P</i><0.001), and a two fold reduced quantity of damaged bio-molecules in their haemolymph (<i>P</i> = 0.036).</p

Representative images of tarantula haemolymph cells after incubation with MitoSOX Red probe.

<p>Fluorescence was mainly localized in the cytoplasm (a) and there was no apparent unspecific labelling of the nucleus (b).</p

Longevity of <i>Brachypelma albopilosa</i> in laboratory (n = 30 for males and n = 10 for females).

<p>These data were measured from different individuals than the ones used for superoxide production. The duration of periods were compared between males and females using a <i>t</i>-test. All inter-sex comparisons are significant, <i>P</i><0.001.</p

Existing and evolving bioethical dilemmas, challenges, and controversies in vascularized composite allotransplantation: An international perspective from the Brocher Bioethics Working Group

Early results of hand and face transplants and other grafts such as those of uterus, penis, trachea, larynx, or abdominal wall have confirmed the potential for vascularized composite allotransplantation (VCA) to restore appearance, anatomy, function, independence, and social integration in patients suffering from devastating tissue deficits untreatable by conventional treatment options. Despite such promise, these novel and complex procedures face challenges and controversies that remain open to discussion and debate. Indeed, many barriers to clinical advancement and negative stakeholder perceptions still exist. The bioethical challenges surrounding VCA include but are not limited to justice and vulnerability of subjects, and their experiences with risks, benefits and outcomes, provider economy of fame, public awareness and attitudes toward transplantation, and policy and regulatory issues shaping progress of the field. The First International Workshop on Bioethical Challenges in Reconstructive Transplantation was organized by the Brocher Foundation in Hermance, Switzerland. VCA professionals representing teams from across the world examined bioethical issues in VCA related to standards for safety, efficacy, feasibility, privacy, confidentiality, and equitability. Key discussion topics from the workshop were included in a survey questionnaire implemented across VCA professionals attending the 13th Congress of International Society of VCA held in Salzburg, Austria. The insights from the Brocher workshop and International Society of VCA survey as presented here could help inform the future development of clinical practice and policy strategies in VCA to ensure value, accessibility, and acceptance of these procedures by potential donors, potential or actual recipients and their families, and providers and payers