Salinitätspräferenzen bei Glasaalen und jungen Gelbaalen(Anguilla anguilla)

Preference experiments have been carried out on elvers and young eels in order to assess locomotory responses to different salinity conditions. Employing different test apparatus it was established that elvers preferred fresh water to water of 18 ‰ and 36 ‰ S. There was no significant difference between responses to water of 18 ‰ and 36 ‰ S. When young yellow eels were offered different salinities (fresh water, 18 ‰ and 36 ‰ S) in tubes, a preference for water of 18 ‰ S was noted. This preference was not influenced by the different salinities in which the eels had previously been kept.     

L'os cellulaire d'un Poisson Téléostéen ≪Anguilla anguilla L.≫

Résumé Le squelette vertébral de l'Anguille est formé d'os cellulaire: lamellaire compact ou spongieux, suivant les différentes parties de la vertèbre. Nous avons pu y mettre en évidence, chez des animaux physiologiquement normaux, les trois catégories de cellules caractéristiques de l'os des vertébrés supérieurs: ostéoblastes, osteocytes, ostéoclastes. Elles ont les mêmes fonctions que chez ces derniers, les ostéoblastes procèdent à l'élaboration du tissu osseux, alors que les ostéoclastes le détruisent; à cette résorption ostéoclastique s'ajoute une lyse périostéocytaire ou résorption périlacunaire. Les osteocytes, dans ce tissu, nous paraissent être des éléments actifs; néanmoins, leur nombre (par unité de surface) est très inférieur à celui trouvé chez les Mammifères. Le remaniement osseux résultant du jeu de l'apposition et de la résorption est important et comparable à celui existant chez l'Homme.L'os de l'Anguille est, à de nombreux points de vue, très voisin de celui des Mammifères; les Poissons n'ont pas de parathyroïdes en tant que telles mais ils sont pourvus d'autres glandes vraisemblablement impliquées dans la régulation phosphocalcique: corps ultimobranchial et corpuscules de Stannius. Notre but sera donc d'essayer de déterminer comment est réglé le métabolisme de l'os cellulaire des Téléostéens.

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Histologic study on teleost cellular bone I.

Summary The vertebral skeleton of the eel consists of cellular bone, either lamellar or spongy, depending on different parts of the vertebra. In this osseous tissue we have found, in physiologically normal animals, three categories of caracteristic cells of the bone of higher vertebrates: osteoblasts, osteocytes, osteoclasts. They have the same functions as in higher vertebrates, osteoblasts form the bone while the osteoclasts which are to be found in Howship's lacunae destroy it. In addition, a perilacunar type of bone resorption or osteocytic osteolysis can be observed. In this bone, osteocytes seem to be active cells, but the concentration of osteocytes is decidedly lower than that to be found in Mammals.The osseous remodeling produced by apposition and resorption is of the same importance as in human bone. The bone of the eel, in many ways, closely resembles that of mammals. Teleost fish do not have parathyroid glands, but their phosphocalcic regulation seems to be facilitated by the action of two endocrine glands: Ultimobranchial body and the corpuscles of Stannius.The regulation of the cellular bone metabolism of Teleostean fishes is discussed.

Nous remercions Monsieur le Professeur Baud qui nous accueille dans son laboratoire à Genève et qui nous prodigue ses conseils.     

Verhalten der Glasaale(Anguilla anguilla) bei ihrer Wanderung in den Ästuarien deutscher Nordseeflüsse

Zusammenfassung 1. Das Verhalten von GlasaalenAnguilla anguilla L., die bei Tage im oberen Tidegebiet der Elbe an der Oberfläche und im Schwarm wanderten, wurde beobachtet.2. Aus diesen und früheren Untersuchungen in der Elbe geht hervor, daß bei Ebbe die Aale ihre Tageswanderung am Ufer etwas unterhalb der Flutstromgrenze in den frühen Morgenstunden beginnen und täglich in den Vormittagsstunden wieder abbrechen. Sie verbergen sich dann im Sand oder unter den Steinen.3. Die täglich weiter flußaufwärts begonnenen Oberflächenwanderungen enden vermutlich an der Tidegrenze oder etwas oberhalb davon und umfassen damit einen Bereich von etwa 50 km.4. Glasaalschwärme wurden am häufigsten an den Tagen, die dem Mitternachtstidehochwasser an der Flutstromgrenze folgten, festgestellt. Diese Erscheinung läßt sich aus dem Verhalten der Glasaale erklären, negativ phototaktisch und passiv mit dem Flutstrom flußaufwärts zu treiben.5. Die Aale halten während der Tageswanderung engen Uferkontakt und lassen sich in ihrer Wanderrichtung, außer bei starker Turbulenz, durch gleichlaufende Strömungen nicht irritieren.6. Das Elbestauwehr wird, außer gelegentlich an der Schleuse, während des beschriebenen Entwicklungsabschnittes nur bei Hochwasser überwunden; dann können die Aale im Bereich überfluteten Geländes in das Gebiet oberhalb des Stauwehrs gelangen.7. Die in der Elbe nachgewiesenen Verhaltensweisen bestätigen sich nach früheren Beobachtungen anderer Autoren und eigenen Ermittlungen in den Flüssen Weser und Ems.8. Das periodische Auftauchen der Glasaale an der Wasseroberfläche im oberen Tidebereich wird dadurch erklärt, daß sich aus der vorangegangenen Zeit im wechselnden Flut- und Ebbstrom ein innerer Rhythmus erhalten hat, der abwechselnd eine positive und negative Rheotaxis auch ohne äußeren Zeitgeber noch einige Tage in Erscheinung treten läßt.9. Die Frage, wie die Aale im äußeren und inneren Küstenabschnitt Ebbe-oder Flutströmungen perzipieren und welche Bedeutung möglicherweise lunaren Einflüssen zukommt, wird diskutiert.

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Behaviour of elvers(Anguilla anguilla) during their migration in estuaries of German North Sea rivers

Upon observing the tidal section of the Elbe River, it was found that the elvers (Anguilla anguilla L.), gathering in shoals immediately below the surface of the water, moved only in the early part of the morning. The area of such below-the-surface movements probably ranges from approximately the uppermost point reached by the flood stream to the uppermost point of measurable vertical tidal fluctuations. In the Elbe this area spreads over a distance of about 50 kilometers. Subsequent to such early day movements, the elvers bury themselves in the river bottom. They are passively carried upstream and, following a midnight high tide, appear at the upper boundary of the flood stream. Above this boundary the elvers swim against the current and close to the river bank. If the direction of the downstream current occasionally changes, for example, due to the special morphology of the river banks, the elvers swim with it, but, in principle, they do not alter their upstream direction of swimming. The elvers reach the section above the weir near Geesthacht only when the water is extremely high and the surrounding land flooded, or, though more seldom, through the sluice. Behavioural patterns and hydrographical relationships similar to those described for the Elbe were found by other authors to exist in the Weser and Ems Rivers. The periodic emergence of the elvers to the surface in the upper tidal region can be explained by previous experiences and resulting internal rhythms, which do not need reinforcements by external factors over shorter periods of time. The question of how ebb and flood streams are perceived in outer and inner coastal waters by the elvers, as well as possible direct and indirect influences through the moon, are discussed.

     

Silvering and gill “mitochondria-rich” cells in the eel,Anguilla anguilla

Gills of typical yellow and silver ells, Anguilla anguilla L., were examined by light and electron microscopy. In both eel types, mitochondria-rich cells were located in the epithelium covering the primary lamellae and consisted ofchloride cells and accessory cells. As compared to yellow eels, the primary gill epithelium of silver eels was thicker and contained larger and more numerous chloride cells with enlarged mitochondria. The accessory cells also increased in number but did not show significant modifications in their size or ultrastructural features. These observations indicate that, as far as mitochondria-rich cells are concerned, the silvering process in eels would be equivalent to smoltification in salmonids. It corresponds to a preparation for seawater life and is probably controlled by hormonal factors.     

Les prémices d'une agriculture diversifiée à la fin du Mésolithique dans le Val de Loire (Loire armoricaine,France)

Pollen analyses carried out in the Armorican Massif have already drawn our attention to the early appearance (at the end of the Mesolithic period/beginning of the Neolithic period) of several taxa, particularly Cerealia. New studies conducted in the Val de Loire region of France and in the surrounding tributaries seem to confirm these initial findings. These studies also provided more information about the introduction of Fagopyrum and Juglans at about 6000 BC. We hypothesise that ‘pre-domesticated’ agriculture took place in this area at this time and that it might have been brought to this area by southern migration. To cite this article: L. Visset et al., C. R. Palevol 1 (2002) 51–58.     

Does a 5500-km swim trial stimulate early sexual maturation in the European eel (Anguilla anguilla L.)?

The catadromous European eel (Anguilla anguilla L.) undertakes a 6000-km spawning migration from its freshwater habitats to the Sargasso Sea. In large Blazka swim tunnels of 127 l, the physiological effect of such a prolonged swimming performance on sexual maturation in adult female eels was investigated. Two groups of eels were placed in swim tunnels for 173 days, one group was able to swim at 0.5 body lengths/second (Swim group) covering a distance of c. 5500-km over the experimental period, and one group kept in static (End Control group). A control group was sampled at the start of the experiment in order to determine the initial stage of reproductive development (Initial Control group). At the end of the swim trial, the maturation parameters 11-ketotestosterone, pituitary levels of LH and plasma levels of estradiol were higher (although not significantly) in the Swim compared to the End Control group. In addition, no significant differences were observed in most measured morphometric and reproductive parameters, including eye-index, gonadosomatic index, hepatosomatic index, and plasma levels of vitellogenin, cortisol and melanophore-stimulating hormone (MSH). Also, pituitary levels of both MSH, and adrenocorticotropic hormone (ACTH) were unaffected. In contrast, the oocyte diameter was found to be significantly higher in the Swim compared to the End Control group. Based on these observations we conclude that a period of prolonged swimming might be a physiological stimulus necessary for the onset of maturation in the European eel.     

Der Einfluß von Temperatur,Futter, Größe und Herkunft auf die sexuelle Differenzierung von Glasaalen(Anguilla anguilla)

The effects of rearing and feeding conditions, as well as of body size and origin on sexual differentiation have been examined in elvers collected on the Atlantik coast (River Ems) and in the Tyrrhenian Sea. Raised at 17°, 20°, 23°, 26° or 29° C and at constant photoperiod, the elvers received either commercial fish food or cod roe. Eels from the Tyrrhenian Sea mostly developed into males. To some extent, at temperatures optimal for growth (26° C) and feeding a cod-roe diet, a shift of sex ratio in favour of females was observed in Atlantic eels. The results obtained contradict those ofFidora (1951), who, rearing elvers in ponds, found the percentage of male eels to be positively correlated with increasing stock density. Although in the present study, stock density was 200 times higher than inFidora's experiments, the percentage of females was much higher than that of males. The results obtained supportBellini's (1907) findings that big elvers preferentially develop into females, but small elvers into males. Irrespective of elvers' origin, water temperature and diet, the onset of sexual differentiation dependends upon attaining a certain body length (15–25 cm), but not on age. Whereas under natural conditions females are supposed to grow faster than males, under the conditions tested the males grew faster than the females. It is concluded, that, in addition to genetic factors, various environmental factors may influence sex determination in eels.     

Paludisme d’importation en France: données actuelles

Le nombre de cas de paludisme d’importation a augmenté régulièrement en France de 1996 à 2001 alors qu’il semble stable ou en diminution dans d’autres pays de l’Union Européenne (1). Il est de 7223 cas estimés pour l’année 2001. Nous avons interrogé le Professeur E. Caumes, Président de la Société de Médecine des voyages, pour un rappel des différents points concernant le paludisme d’importation.     

鳗鲡(Anguilla japonica)人工育苗技术研究进展

鳗鲡（Ａｎｇｕｉｌｌａｊａｐｏｎｉｃａ）人工育苗技术研究进展马海飞（中国科学院发育生物学研究所,北京１０００８０）一、鳗鲡人工育苗技术研究的意义鳗鲡养殖是我国及周边国家和地区水产动物养殖业的一项重要内容,也是我国水产养殖的主要创汇项目之一。我国周边地区和国家鳗鲡养殖中使用的鳗鲡苗主要产自我国,全部为天然苗。鳗鲡的产卵场在我国沿海附近。每年春季鳗苗进入我国河口水域。由于自然资源自身的产量有限,加上工业污染造成资源破坏,现 在天然苗的捕获量已经越来越不能满足日趋增长的市场需求,因此人工繁殖鳗苗技术的研究和开发已迫在眉睫。     

Characterization of pore-forming activity in liver mitochondria from Anguilla anguilla. Two porins in mitochondria?

A fast purification procedure for the isolation and purification of eukaryotic porin (De Pinto et al., (1987) Biochim. Biophys. Acta 905, 499-502) was applied to liver mitochondria of the fish Anguilla anguilla. A protein preparation was obtained which formed slightly anionically selective pores in reconstitution experiments with lipid bilayer membranes. The distribution of single-channel conductances had two maxima of 2.4 nS and 4.0 nS in 1 M KCl. Sodium dodecylsulfate electrophoretograms of the protein preparation showed the presence of two bands of very similar electrophoretic mobility (32 and 32.5 kDa). Both bands cross-reacted with antibodies raised against purified bovine heart porin and with antibodies raised against the 19 amino acids N-terminal end of human porin. No cross-reactivity was observed with antibodies against yeast porin. The peptide maps of the two bands showed slight differences. The possibility of the presence of two different porins in liver mitochondria of Anguilla anguilla is discussed. An extensive immunological comparison of different mitochondrial porins is presented.     

Cycle évolutif de Bucephalus anguillae Spakulová, Macko,Berrilli & Dezfuli, 2002 (Digenea,Bucephalidae) parasite de Anguilla anguilla (L.)

The species of Bucephalus from the eel Anguilla anguilla of the north-eastern Tunisian lagoons was identified as B. anguillae which was recently described by pakulová et al. (2002) from the Adriatic coast of Italy. In order to confirm that this eel digenean is distinct from B. polymorphus von Baer, 1827 present in other freshwater fishes, we investigated the life-cycle of this species. Surveys in the wild and experimental studies have shown that the life-cycle of B. anguillae is completed in brackish environments, with the lamellibranch Abra tenuis as the first intermediate host and the cyprinodontid fish Aphanius fasciatus as the second intermediate host. This life-cycle differs from that of B. polymorphus and can be considered as an additional argument for the distinction of these two morphologically similar species.     

Halyomorpha halys (Stål 1855) en Île de France (Hemiptera : Pentatomidae : Pentatominae) : surveillons la punaise diabolique

Le Pentatomidae (Insecta : Hemiptera) d’origine asiatique Halyomorpha halys (Stal 1855) a été trouvée en Ile de France (Paris intra muros et Lardy, Essonne) à la fin de l’année 2013. Ces occurrences font suite à celle de l’été 2013 dans l’agglomération de Strasbourg, près de la frontière allemande. Il s’agit de la 5^e mention de cette espèce en Europe après la Suisse, l’Allemagne, et l’Italie. Il serait nécessaire de surveiller l’expansion de cette espèce polyphage et dommageable à des nombreuses cultures, dont l’expansion en Europe est très rapide, et qui peut être un agent allergénique.     

Inter-annual variability in the environmental performance of viticulture technical management routes—a case study in the Middle Loire Valley (France)

Purpose

Improving the environmental performances of viticulture practices is particularly complicated during unfavorable climatic conditions because of the need for fungal and other pest pressure and the variability of phytosanitary control methods available for winegrowers. However, winegrowers wish to improve the environmental performances of their practices regardless of climatic conditions. The objective of the study was to quantify the variability in environmental impacts due to climatic variations, and changes in viticulture practices induced by climatic variability.

Methods

Life cycle assessment was used to evaluate the environmental impacts of viticulture technical management routes (TMR) implemented on five plots in the Loire Valley for the Chenin Blanc grape variety. These TMRs are representative of the range of practices used in the region, including intensive conventional practices to moderate organic practices. The study covered two different years of production (2011 and 2013) under contrasting climatic conditions. The first year (2011) was hot and dry, which are favorable conditions for viticulture, while the second year (2013) was cold and humid, which are unfavorable conditions.

Results and discussion

During the unfavorable year, the number of phytosanitary treatments and soil maintenance interventions increased for most of the studied TMRs. This meant that the inter-annual variability in environmental impact was significant, depending on the type of TMR, with differences in impacts ranging from 19% to more than 40% between 2011 and 2013. Managing environmental impacts was found to be more difficult for the organic systems when climatic conditions are unfavorable (in 2013). The non-organic TMRs showed less variation in environmental impacts than the organic TMRs between the 2 years studied.

Conclusions

This study shows the importance of taking into account inter-annual variability in environmental assessments of viticulture systems. Indeed, winegrowers do not respond the same way to climate variability mainly with regard to plant protection and soil maintenance. Viticulture is very sensitive to inter-annual climate variations due to the parasitic pressure variability. The different production systems do not give to winegrowers the same possibilities for adapting practices to limit their impact on the environment.

     

Réévaluation des dosages de PSA disponibles en France en 2012

The evaluation kits PSA conducted in 2004 by AFSSAPS resumed in 2012 using the same methodology to update the performance of assays available on the French market. Preference should be given to equimolar and accurate assays of PSA for uniform clinical use and correct kinetic monitoring.     

H+ and Cl− secretion in the stomach of the teleost fish, Anguilla anguilla : stimulation by histamine and carbachol

The fundus of an eel stomach was mounted in an Ussing chamber and bathed with control Ringer on the serosal side and with unbuffered solution on the mucosal side. The gastric mucosa exhibited a mucosa negative transepithelial voltage (V _t), a “short circuit” current (I _SC) and a small spontaneous acid secretion rate (J _H). All these parameters were abolished by cimetidine treatment. Bilateral ion substitution experiments in tissues lacking spontaneous acid secretion suggested that a net Cl⁻ transport from serosa to mucosa was responsible for the genesis of the I _SC in the absence of H⁺ secretion. Serosal application of histamine (10⁻⁴ mol · l⁻¹) or carbachol (10⁻⁴ mol · l⁻¹) stimulated both I _SC and J _H. The action of carbachol was independent of histamine. The control as well as the histamine-stimulated I _SC was sensitive to both serosal bumetanide (10⁻⁵ mol · l⁻¹), inhibitor of the Na⁺-K⁺-2Cl⁻ cotransport, and 4,4-diisothiocyano-stilbene-2,2-disulphonic acid (DIDS, 5 · 10⁻⁴ mol · l⁻¹), inhibitor of the Cl⁻-HCO⁻ ₃ exchange, while the I _SC stimulated by carbachol was nullified by serosal DIDS. These data suggested that the non-acidic Cl⁻ uptake across the serosal membrane was linked to the activity of both Na⁺-K⁺-2Cl⁻ cotransport and Cl⁻-HCO⁻ ₃ antiporter; histamine stimulated both transporters while carbachol was limited to the anion exchanger. The finding that the acid secretion was strictly dependent on serosal Cl⁻ and was completely blocked by serosal DIDS suggested that the Cl⁻ accompanying H⁺ secretion entered the cell through the serosal membrane by the Cl⁻-HCO⁻ ₃ exchange. In addition, the acid secretion stimulated by carbachol was also dependent on serosal Na⁺ and sensitive to the application of 5-N-N-dimethyl-amiloride in the serosal bath, suggesting that the increased activity of the Cl⁻-HCO⁻ ₃ during carbachol treatment was linked to the activation of serosal Na⁺-H⁺ exchange. The inhibitory effect of luminal omeprazole (10⁻⁴ mol · l⁻¹) on acid secretion suggested the presence of the H⁺-K⁺ pump on the luminal membrane. Accepted: 18 September 1997     

Is the continental life of the European eel Anguilla anguilla affected by the parasitic invader Anguillicoloides crassus?

Quantifying the fitness cost that parasites impose on wild hosts is a challenging task, because the epidemiological history of field-sampled hosts is often unknown. In this study, we used an internal marker of the parasite pressure on individual hosts to evaluate the costs of parasitism with respect to host body condition, size increase and reproductive potential of field-collected animals for which we also determined individual age. In our investigated system, the European eel Anguilla anguilla and the parasitic invader Anguillicoloides crassus, high virulence and severe impacts are expected because the host lacks an adaptive immune response. We demonstrated a nonlinear relationship between the severity of damage to the affected organ (i.e. the swimbladder, our internal marker) and parasite abundance and biomass, thus showing that the use of classical epidemiological parameters was not relevant here. Surprisingly, we found that the most severely affected eels (with damaged swimbladder) had greater body length and mass (+11% and +41%, respectively), than unaffected eels of same age. We discuss mechanisms that could explain this finding and other counterintuitive results in this host–parasite system, and highlight the likely importance of host panmixia in generating great inter-individual variability in growth potential and infection risk. Under that scenario, the most active foragers would not only have the greatest size increase, but also the highest probability of becoming repeatedly infected—via trophic parasite transmission—during their continental life.