Reproductive Cycle and Plasma Levels of Sex Steroids in Female Eurasian Perch Perca Fluviatilis

From April 1995 to April 1996, the annual reproductive cycle of the Eurasian perch Perca fluviatilis was studied at the Fishfarming Lindre Center (Moselle, France). At monthly intervals (at intervals of 10 days during the periovulatory period), 5 females were caught and dissected. From sampled organs, the gonado-, hepato- and viscerosomatic indexes (GSI, HSI, VSI) were calculated, oocyte diameters (OD) and the plasma levels of testosterone (T), 17P-estradiol (E2), 17,20P-dihydroxy-4-pregnen-3-one (17,2Op-P) and protein-phosphorus (PPP) were measured. After the sexual resting period observed from May to August (GSI \u3c 1 %, OD \u3c 200 urn, VSI = 4-6 %), oogenesis began in September when the water temperature decreased from 26.4 to 14.1 “C. The GSI increased progressively until mid March (15 %), then rapidly until spawning (25 %, OD = 850 urn) which occurred in April (14- 15 “C). The plasma levels of T, E,, 17,2Op-P and PPP were low during the sexual resting period. E, and PPP levels increased significantly at the onset of the oogenesis in September, then the E, level raised abruptly in November (3-4 ng mL-‘). In December, the T level increased rapidly to 15-20 ng . mL-’ The testosterone, E, and PPP levels remained very high until spawning, indicating the existence of active vitellogenesis. The highest HSI (2.1-2.2 %) recorded in winter confirmed this. During the periovulatory period, a peak of E, (4 ng . mL-‘) appeared, whereas T level diminished. In this study, 17,2Op-P levels remained low (0.2-0.6 ng mL-‘) and relatively constant. No 17,2Op-P peak was observed during the periovulatory period. Sampling at 10 day intervals was probably inadequate to specify the hormonal variations related to the final oocyte maturation and the ovulation. 0 Ifremer-Elsevier, Paris

Reproductive Cycle and Plasma Sex Steroid Profiles in Male Eurasian Perch Perca Fluviatilis

From April 1995 to April 1996, the annual reproductive cycle of male Eurasian perch Perca fluviatilis was studied at the Lindre Center (Moselle, France). At monthly intervals, five males (mean body weight of 133 ± 43 g and total length of 175 ± 9 mm) were caught. From sampled organs, the gonadosomatic (GSI), hepatosomatic (HSI) and viscerosomatic indexes (VSI) were calculated and plasma testosterone (T) and 11-ketotestosterone (11KT) levels were measured. After the spawning period in mid-April, GSI and HSI dropped and VSI increased to 3.8 ± 0.1 %. In September, GSI reached its maximum (8.5 ± 1.8 %). At this time, spermatocytes, spermatids and spermatozoa were abundant, whereas in June only spermatogonia were observed. During winter, GSI was stable at approximately 5 %, HSI reached its maximum (1.9 ± 0.3 %) and VSI was low (2.6 ± 0.2 %). From April to November 1995, plasma T and 11KT concentrations were low (\u3c 0.5 ng·mL–1). Plasma T levels increased significantly in December and reached peak levels (12.3 ± 2.1 ng·mL–1) in January, then decreased in February and increased again until spawning in April (6.8 ± 2.1 ng·mL–1). This second elevation could be related to the beginning of a new spermatogenic cycle. Plasma levels of 11KT increased significantly from October to February 1996 (4.9 ± 1.1 ng·mL–1). From February to the spawning period (April 1996), plasma 11KT decreased significantly, but values were significantly higher than those measured in fall. Males were spermiating from January to spawning in April. © 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Éditions scientifiques et médicales Elsevier SA

Determining crystal structures through crowdsourcing and coursework

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality

Les fondements utilitaristes et anti-utilitaristes de la coopération en biologie

Alors que les sciences naturelles ont semblé donner raison à l’utilitarisme pendant plus d’un demi-siècle, il devient aujourd’hui possible de contredire cette hypothèse :l’homme n’est pas uniquement égoïste, en plus du fait qu’il n’est pas parfaitement rationnel. Ce non-utilitarisme de l’être humain s’applique aux formes les plus primitives de la vie :la coopération est inscrite dès les origines et pourrait être un des moteurs essentiels de l’évolution. La découverte récente de mécanismes permettant la naissance de la coopération dans un contexte de gènes postulés égoïstes remet cent ans de débats socio-logiques sur la table de travail.During the last 50 years, life sciences seemed to demonstrate that utilitarianism was the only possible evolutionary pathway, closing the debate in social sciences. The latest converging results of studies using more complexe, less biaised models and behavioural experiments suggest today that this hypothesis was fundamentally wrong: humans are neither rational nor perfectly selfish. This non-utilitarianism of Human Beings is also a characteristic of primitive life forms: cooperation has existed since the origine of life and could even be one of the fundamental motors of evolution. The recent parallel discovery of various mecanism allowing the apparition and survival of cooperation in a context of postulated selfish genes revitalizes a 100 years old sociological debate.info:eu-repo/semantics/publishe

The bottom-up assessment of threatened species

Identifying the percentage of endangered species is crucial for the protection of biodiversity from local to global levels. However, the high costs of species evaluation jeopardise the feasibility of evaluating all world species. We propose a model to consolidate imperfect local assessments to a first (conservative) estimation of national to global assessment. We used it for the evaluation of 8132 Belgian species starting with incomplete red lists at lower geographic levels (Belgian regions). The model is based on the logical assumption that if a species is safe («Least Concern») at local level (> 10 000 km2), then it is safe at global level. It can be used at various geographic levels to help aggregate imperfect local red lists into a first estimate of global ones. Testing the model shows that it gives very conservative results because less species are evaluated endangered at global level than when using other methods. Our model can deal with non-standard local red lists, with an error range that is reducing when local red lists become compliant with the IUCN standards. It cannot and does not aim to replace full IUCN-compliant assessments. We show the value of publishing the lists of currently safe species-not only those that are threatened. Actually, in the light of the sixth mass extinction, identifying safe species becomes as important as those that are endangered. We encourage trained biologists to evaluate less-known groups like invertebrates, algae, or microfungi. Our model facilitates a low cost first rough conservative estimate at global level. This can help historical reviews as well as identifying research and policy priorities. Our tests question the IUCN guidelines for species that are stable but only present in areas smaller than a few km2.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe

Les modèles de développement et les histoires d’évolution à l’épreuve de l’incertitude radicale et de l’irréversibilité

Les théories du développement économique et de l’évolution biologique reposent sur une série de conditions fondamentales communes, comme la réversibilité (ou le déterminisme) et la mesurabilité. La réversibilité suppose une régularité minimale des phénomènes (comme la course cyclique des planètes dans le ciel). Sauf accident ou vieillissement, il y a moyen de prédire, calculer et optimiser le déplacement d’un train sur les rails ou la course d’une fusée dans l’espace. En science humaine, le corpus normatif et institutionnel passé a un impact sur les décisions présentes, mais les normes futures n’ont pas d’impact sur le passé. Cette irréversibilité de la capitalisation normative empêche de prédire le comportement ou les aspirations des générations futures. La mesurabilité permet de connaître et d’élaborer des outils d’optimisation ou de prévision. L’incertitude probabiliste (erreurs de mesure ou phénomènes peu fréquents) permet de gérer le risque sans sortir des « lois » déterministes. C’est ce à quoi s’attachent les scientifiques qui évaluent le risque climatique. Nous montrons en quoi la flèche du temps et l’incertitude radicale (non probabilisable) peuvent mettre à mal des théories aussi affirmées que la théorie économique et la théorie de l’évolution. En prenant des exemples dans le champ de la biologie, de l’économie et de leurs modèles, nous allons montrer en quoi « la réponse est dans la question » ou comment des hypothèses et des théories se renforcent mutuellement pour ne décrire in fine qu’un monde fictif. Dans ce monde fictif, malheureusement éloigné de la réalité, il y a des lois physiques, des lois naturelles et des lois historiques. Dans le monde réel, des savants se basent sur ces lois pour nous dire ce qu’il faut faire afin d’éviter le chaos, lequel continue, malgré cette belle assurance, à inquiéter le commun des mortels.info:eu-repo/semantics/publishe

Indicators of sustainable development: fundamentals and applications

Existe-t-il un consensus scientifique sur les conditions de la durabilité ?Est-il possible de construire un indicateur unique de soutenabilité faible ?Quelles sont les composantes objectives et subjectives des indicateurs ?Peut-on envisager des indicateurs objectifs de soutenabilité ?Quelles voies de recherche sont-elles nécessaires pour développer des indicateurs de développement durable ?Telles sont les questions auxquelles cet ouvrage tente de répondre.La comparaison des courants de la soutenabilité faible et de la soutenabilité forte nous sert de fil conducteur pour évaluer la part normative et la part objective du choix des paramètres et de leur méthode d'agrégation. L'agrégation arithmétique implique des hypothèses de substituabilité entre les facteurs, ce qui relève de la soutenabilité faible. La pondération, toujours normative, peut être explicite ou se traduire par le choix d'une unité ou dimension unique. Nous redéfinissons la soutenabilité faible comme étant la réduction de la complexité à une dimension unique. Il y a dès lors autant d'indicateurs de soutenabilité faible que de choix possibles de cette dimension unique. En particulier, l'empreinte écologique par habitant relève d'une forme "écologique" de soutenabilité faible. Le prix de marché est l'unité fondamentale de mesure de sa forme "économique". Nous montrons que les acteurs ne savent pas bien identifier leur intérêt et qu'ils ne sont pas parfaitement égoïstes, ce qui introduit un biais non systématique remarquable dans toute mesure en unité monétaire. La soutenabilité forte se caractérise par la multiplicité de dimensions ou "capitaux critiques" dont le dépassement d'un seul suffit à déterminer la non soutenabilité. Les différentes formes de soutenabilités faibles peuvent représenter des capitaux critiques parmi d'autres.Nous présentons une typologie des acteurs et du partage des responsabilités, également susceptible d'introduire des grandes divergences dans les résultats publiés. Quelques études de cas illustrent ces différents éléments dans des contextes contrastés. L'empreinte écologique de consommation se limite en particulier à une responsabilisation du seul consommateur, alors que les comptes nationaux permettent d'envisager la coresponsabilité de l'ensemble des acteurs. L'indicateur de "dématérialisation de l'économie" appliqué à un village indien montre la pertinence de mesurer l'utilisation absolue de matière sans pondération monétaire. Il est par ailleurs possible de minimiser le coût de dépollution sans toucher à la limite absolue d'émissions globales de centrales thermiques. Les deux dimensions, coûts sociaux et bénéfices environnementaux, peuvent donc être traitées séparément.En conclusion, il est possible d'identifier, dans chaque calcul d'indicateur de développement durable, une composante relativement objective de soutenabilité "forte" et une composante "faible", négociable, de partage des droits et responsabilités./ We study how different world views may influence how to develop sustainable development indicators. The comparison of weak sustainability and strong sustainability serves as a guide to estimate the share of objective versus normative choice of parameters and their method of aggregation. We then present a typology of actors and shared responsibilities, which may also introduce large discrepancies in the results published. Some case studies illustrate these different elements in contrasting contexts. It appears that it is possible to identify in each calculation of sustainable development indicator, a relatively objective component of sustainability and a negotiable component of shared rights and responsibilities.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

A Model of Emission Trading for Minimizing the Cost of Air Pollution Control from Belgian Power Plants

In Belgium recent national and community legislation regulates emission levels of "acid pollutants" (SO2, NOx) and apply to large combustion facilities whose pollutants are transported over large distances. Complying with these legislations requires costly emission control equipment. In order to minimize the costs of clean-up operations, this paper analyses the potentialities of an emission trading programme by means of a linear programming model. Six retrofit power plants have been chosen to test the model. As the results suggest, substantial credits are obtained for either SO2 or NOx emissions reduction.info:eu-repo/semantics/publishe

Impacts sur l’environnement de l’Europe de l’Ouest et de l’Afrique de l’Ouest :essai de comparaison sur base d’indicateurs

info:eu-repo/semantics/publishe

A Model of Emission Trading for Minimizing the Cost of Air Pollution Control from Belgian Power Plants

In Belgium recent national and community legislation regulates emission levels of "acid pollutants" (SO2, NOx) and apply to large combustion facilities whose pollutants are transported over large distances. Complying with these legislations requires costly emission control equipment. In order to minimize the costs of clean-up operations, this paper analyses the potentialities of an emission trading programme by means of a linear programming model. Six retrofit power plants have been chosen to test the model. As the results suggest, substantial credits are obtained for either SO2 or NOx emissions reduction.emission trading, linear programming model, power plants, SO2, NO