Temperature and size-dependency of lumpfish (Cyclopterus lumpus) oxygen requirement and tolerance

Under embargo until: 2023-10-09Lumpfish are currently produced and utilized as cleaner fish, to control sea lice infestation rates in salmon net pens, but information on environmental requirements is still limited. This study aimed to determine the zone of environmental hypoxia for two relevant fish sizes (15 and 60 g) and temperatures (5 and 12 °C), using intermittent flow respirometry (referred to as 15:5, 15:12, 60:5, 60:12), and to investigate parameters of stress in response to acute changes in dissolved oxygen (DO, % air saturation) from normoxia to 47, 63, 98 (control), 148 and 194% O2 at 10 °C. The standard and maximal metabolic rates (SMR and MMR) were measured in normoxia (n = 8), and MMR was measured at 5–6 DO levels ranging from 20−160% O2 (n = 8 per DO) to define the upper and lower boundaries of the hypoxic zone (DOlim and DOcrit). SMR, MMR and the aerobic metabolic scope (AS) increased with temperature and decreased with fish size. Similar effects of temperature and size were found on DOcrit – DOlim ranges: 20–55 (15:5), 35–147 (15:12), 21–53 (60:5) and 22–89 (60:12) % O2 air saturation. Results from acute exposure tests resulted in elevated cortisol levels at 63 and 47% O2, although not statistically significant at 47% O2. Other parameters of hypoxic or hyperoxic stress (lactate, pH, osmolality, lipid peroxidation rates, catalase activity) were not affected. Results from the present study suggest that lumpfish may experience oxygen levels in sea cages that restricts metabolism, performance and induce hypoxic stress.acceptedVersio

Differentiated skeletal cells contribute to blastema formation during zebrafish fin regeneration

The origin of cells that generate the blastema following appendage amputation has been a long-standing question in epimorphic regeneration studies. The blastema is thought to originate from either stem (or progenitor) cells or differentiated cells of various tissues that undergo dedifferentiation. Here, we investigate the origin of cells that contribute to the regeneration of zebrafish caudal fin skeletal elements. We provide evidence that the process of lepidotrichia (bony rays) regeneration is initiated as early as 24 hours post-amputation and that differentiated scleroblasts acquire a proliferative state, detach from the lepidotrichia surface, migrate distally, integrate into the blastema and dedifferentiate. These findings provide novel insights into the origin of cells in epimorphic appendage regeneration in zebrafish and suggest conservation of regeneration mechanisms between fish and amphibians.Fundacao para a Ciencia e Tecnologia (FCT), Portugal; FCT [PTDC/SAU-OBD/100200/2008, PTDC/SAU-OBD/73112/2006]; Ramon y Cajal; MCIN, Spain; Medical Research Council [G0700091B

Gene Expression During the First 28 Days of Axolotl Limb Regeneration I: Experimental Design and Global Analysis of Gene Expression

While it is appreciated that global gene expression analyses can provide novel insights about complex biological processes, experiments are generally insufficiently powered to achieve this goal. Here we report the results of a robust microarray experiment of axolotl forelimb regeneration. At each of 20 post-amputation time points, we estimated gene expression for 10 replicate RNA samples that were isolated from 1 mm of heterogeneous tissue collected from the distal limb tip. We show that the limb transcription program diverges progressively with time from the non-injured state, and divergence among time adjacent samples is mostly gradual. However, punctuated episodes of transcription were identified for five intervals of time, with four of these coinciding with well-described stages of limb regeneration—amputation, early bud, late bud, and pallet. The results suggest that regeneration is highly temporally structured and regulated by mechanisms that function within narrow windows of time to coordinate transcription within and across cell types of the regenerating limb. Our results provide an integrative framework for hypothesis generation using this complex and highly informative data set

Compatibilité études de médecine et sport ? (l'exemple du rugby)

La coupe du monde de rugby en 2007 a, de manière surprenante, vu s affronter deux médecins joueurs de l équipe d Argentine à un médecin de l équipe d Afrique du Sud lors d une demi finale. A partir de cet événement, notre thèse a voulu comptabiliser l ensemble des médecins ayant joué au niveau international en rugby en recherchant les raisons de cette présence dans un sport de haut niveau et les possibilités qu un médecin français puisse y accéder de nouveau. Pour répondre à cette question, une enquête a été faite auprès de fédérations nationales de rugby et auprès des 30 médecins des clubs de rugby français professionnels. Enfin nous avons réalisé une étude sur la pratique sportive des étudiants de la faculté de médecine d Amiens. On a recensé 12 médecins ou chirurgiens étrangers ayant concouru pour 8 nations différentes en coupe du monde et 34 dont 3 français dans les différentes équipes nationales. La tradition universitaire et la professionnalisation tardive du rugby expliquent ce nombre important. Ceci va probablement disparaître progressivement. A l opposé du sport de haut niveau, la pratique du sport par les 125 étudiants en médecine que nous avons suivis est faible. Ils ne sont que 50 % à se dépenser régulièrement. Le passage du concours en PCEM1 fait chuter leur activité et la reprise du sport est difficile. Pourtant à défaut de fabriquer des champions qui concourraient au niveau mondial, il est nécessaire de promouvoir l activité physique chez les étudiants ce qui leur assurera des bénéfices personnels ainsi qu à leurs futurs patients. En soutien des actions locales, nous attendons la future réforme sport et université des ministères de la santé et de l enseignement supérieurAMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

How to define the size of a sampling unit to map high resolution spatial data?

International audienceThe development and the release of sensors able to provide data with a high spatial resolution (> 4000 points.ha-1 for some of them) in agriculture raises new questions as to how to represent the information. This study proposes adaptation and application of a theoretical framework to high resolution data in agriculture to explain how changes in sampling unit (SU) affects: i) the total variance of the data, ii) the nugget effect (C0) as well as iii) the proportion of variance corresponding to spatially correlated component (C1). The theoretical approach has been validated on simulated data with known characteristics and on real data sets (total soluble solids of grapes just before harvest). Application of this methodology demonstrated that for the type of data under consideration, increasing the SU resulted in an expected decrease in C0 and C1 simultaneously and in an independent decrease in C0. Our study demonstrates that it is not possible to find a SU that maximizes C1 while minimizing C0. It also demonstrates that for a given increase in the SU, the decrease in C0 depends only on the sample support (the size of the SU). The choice of an optimal SU can therefore be based on the resolution of the available information and the C0 value of the raw data

Développement d'un appareil permettant de prédire la maturité du raisin par spectroscopie proche infra-rouge(PIR)

La qualité optimale des vendanges dépend étroitement du choix de la date des vendanges. Différents critères de qualité du raisin sont donc suivis au cours de sa maturation. La spectroscopie visible proche infrarouge (Vis-NIR) permet d'analyser rapidement la composition des produits de manière non-destructive. Cet article présente le développement d'un capteur basé sur l'utilisation de la spectroscopie Vis-NIR destiné au suivi de maturité, le Spectron. Il permet de connaître le taux de sucre, l'acidité totale, la teneur en eau et la concentration en anthocyanes du raisin, qui sont directement mesurés sur la parcelle. Il a été mis au point par la société Pellenc S.A.en partenariat avec l'équipe de l'UMR-ITAP du Cemagref de Montpellier