Spatio-temporal distribution of phototrophic sulfur bacteria in the chemocline of meromictic Lake Cadagno (Switzerland)

In situ hybridization was used to study the spatio-temporal distribution of phototrophic sulfur bacteria in the permanent chemocline of meromictic Lake Cadagno, Switzerland. At all four sampling times during the year the numerically most important phototrophic sulfur bacteria in the chemocline were small-celled purple sulfur bacteria of two yet uncultured populations designated D and F. Other small-celled purple sulfur bacteria (Amoebobacter purpureus and Lamprocystis roseopersicina) were found in numbers about one order of magnitude lower. These numbers were similar to those of large-celled purple sulfur bacteria (Chromatium okenii) and green sulfur bacteria that almost entirely consisted of Chlorobium phaeobacteroides. In March and June when low light intensities reached the chemocline, cell densities of all populations, with the exception of L. roseopersicina, were about one order of magnitude lower than in August and October when light intensities were much higher. Most populations were evenly distributed throughout the whole chemocline during March and June, while in August and October a microstratification of populations was detected suggesting specific eco-physiological adaptations of different populations of phototrophic sulfur bacteria to the steep physico-chemical gradients in the chemocline of Lake Cadagn

Phototropic sulfur and sulfate-reducing bacteria in the chemocline of meromictic Lake Cadagno, Switzerland

Lake Cadagno, a crenogenic meromictic lake located in the catchment area of a dolomite vein rich in gypsum in the Piora Valley in the southern Alps of Switzerland, is characterized by a compact chemocline with high concentrations of sulfate, steep gradients of oxygen, sulfide and light and a turbidity maximum that correlates to large numbers of bacteria (up to 107 cells ml-1). The most abundant taxa in the chemocline are large- and small-celled purple sulfur bacteria, which account for up to 35% of all bacteria, and sulfate- reducing bacteria that represent up to 23% of all bacteria. Depending on the season, as much as 45% of all bacteria in the chemocline are associated in aggregates consisting of different populations of small-celled purple sulfur bacteria of the genus Lamprocystis (up to 35% of all bacteria) and sulfate-reducing bacteria of the family Desulfobulbaceae (up to 12% of all bacteria) that are almost completely represented by bacteria closely related to Desulfocapsa thiozymogenes. Their association in aggregates is restricted to small-celled purple sulfur bacteria of the genus Lamprocystis, but not obligate since non-associated cells of bacteria related to D. thiozymogenes are frequently found, especially under limited light conditions in winter and early summer. Aggregate formation and concomitant growth enhancement of isolates of both partners of this association suggests synergistic interactions that might resemble a sulfide-based source-sink relationship between the sulfate-reducing bacterium that is able to sustain growth by a disproportionation of inorganic sulfur compounds (sulfur, thiosulfate, sulfite), with the purple sulfur bacteria acting as a biotic scavenger. The availability of these isolates opens up the door for future studies considering other facets of potential interactions in aggregates since both types of organisms are metabolically highly versatile and interactions may not be limited to sulfur compounds only

Impacts de l’utilisation des eaux polluées en agriculture urbaine sur la qualité de la nappe de Dakar (Sénégal)

L’agriculture urbaine de la région de Dakar est un secteur en plein essor. À cause de la salinisation progressive des eaux de la nappe peu profonde (eaux de Céanes ), des eaux usées brutes sont utilisées pour irriguer les champs. L’objectif de notre étude est d’évaluer la qualité chimique et microbiologique des eaux de la nappe sous-jacentes aux champs irrigués et d’identifier les sources de pollution. Notre travail a été effectué dans les sites de Pikine et de Patte d’Oie.L’analyse de la qualité chimique des eaux d’arrosage a montré qu’à Pikine, la conductivité des eaux de Céanes est plus élevée (4822±2411 µS cm-1) par rapport à celle des eaux usées (3579±1242 µS cm-1 ; p<0.04). Par contre à Patte d’Oie, les eaux d’arrosage sont moins salées (<3000 µS cm-1). La quantité d’azote total de tous les types d’eaux d’arrosage est supérieure à la valeur guide de l’OMS (5-30 mg l-1).Salmonella spp. a été isolée dans 35 % des eaux d’arrosage. Un échantillon d’eaux usées a été positif pour Vibrio cholerae.L’impact des eaux d’irrigation sur la qualité chimique et microbiologique de la nappe d’eau souterraine est fortement influencé par la pluviométrie et est différent selon le site considéré.Ce travail a montré que l’irrigation avec les eaux polluées et l’usage de fumiers organiques peut altérer la qualité de la nappe et constituer des risques pour la santé.In Dakar capital city of Senegal, the urban agriculture is in high expansion. Since the progressive increase of salinity in the local groundwater (Céanes water), raw wastewater is used to water the crops. The objective of this study is to assess chemical and microbiological quality of the groundwater underlying the irrigated plots and to identify the sources of pollution. This work was carried out in the sites of Pikine and Patte d’Oie in Dakar Senegal.Chemical analysis of irrigation water showed that in Pikine, the conductivity of Céanes water was higher (4822±2411 µS cm-1) than those of the wastewater (3579±1242 µS cm-1 ; p<0.04), while at Patte d’Oie it was less salted (<3000 µS cm-1). The quantity of total nitrogen of irrigation water in both sites was higher than the WHO’s threshold (5-30 mg l-1).Salmonella spp. was isolated in 35 % of the irrigation water. One wastewater sample was Vibrio cholerae positive.The impact of irrigation water on the chemical and microbiological quality of the groundwater is strongly influenced by precipitations and is different according to the site considered.This work showed that the use of polluted water and organic manures can spoil the quality of the groundwater and constitute a health threat.Urban agricultur

Common variability in oestrogen-related genes and pancreatic ductal adenocarcinoma risk in women

The incidence of pancreatic ductal adenocarcinoma (PDAC) is different among males and females. This disparity cannot be fully explained by the difference in terms of exposure to known risk factors; therefore, the lower incidence in women could be attributed to sex-specific hormones. A two-phase association study was conducted in 12,387 female subjects (5436 PDAC cases and 6951 controls) to assess the effect on risk of developing PDAC of single nucleotide polymorphisms (SNPs) in 208 genes involved in oestrogen and pregnenolone biosynthesis and oestrogen-mediated signalling. In the discovery phase 14 polymorphisms showed a statistically significant association (P < 0.05). In the replication none of the findings were validated. In addition, a gene-based analysis was performed on the 208 selected genes. Four genes (NR5A2, MED1, NCOA2 and RUNX1) were associated with PDAC risk, but only NR5A2 showed an association (P = 4.08 × 10−5) below the Bonferroni-corrected threshold of statistical significance. In conclusion, despite differences in incidence between males and females, our study did not identify an effect of common polymorphisms in the oestrogen and pregnenolone pathways in relation to PDAC susceptibility. However, we validated the previously reported association between NR5A2 gene variants and PDAC risk

Piora - Lago di Cadagno - Ritom : Guide nature et environnement / Guida natura e ambiente

Français: «Aucune autre vallée du Canton du Tessin ne jouit d'une telle renommée et attire autant de visiteurs que le Val Piora, qui fait maintenant partie des vallées élevées les plus connues d'Europe». C'est de cette façon que l'Encyclopédie géographique suisse présentait la région en 1905. En effet, de par sa géologie et une richesse minéralogique extraordinaires, ses anciens lacs glaciaires, une flore à forte diversité, et enfin ses magnifiques alpages, le Val Piora constitue un vrai paradis et une région de prédilection pour les recherches et excursions naturalistes. Mais c'est également un lieu de passage incontournable: à travers le Passo dell'Uomo, le Passo Columbe et le Passo del Sole, il est possible de rejoindre le Lukmanier; le Passo de Predelp communique avec la Leventina. Depuis le Val Cadlimo on rejoint le Col de l'Oberalp, en passant par le Passo Bornengo et, en passant par le Val Canaria, le Col du St Gothard. Parmi les nombreuses publications qui concernent la région, on peut mentionner le guide d'excursion édité par l'Atlas hydrologique suisse et le livret publié à l'occasion de l'inauguration du Sentier didactique du Ritóm. Le guide nature et environnement présenté ici propose une information scientifique de base et des itinéraires qui incluent à la fois les itinéraires décrits par les deux guides susmentionnés et des sites complémentaires, se référant à la géologie et à la minéralogie. De nombreuses publications scientifiques sont énumérées dans les bibliographies et peuvent en partie être déchargées sur le site internet www.cadagno.ch, du Centre de biologie alpine (Centro Biologia Alpina, CBA) à Piora. On incite ainsi le naturaliste à se référer à la littérature spécialisée pour approfondir ses connaissances et combler d'éventuelles lacunes. Ce guide comble ainsi un manque d'informations et de méta-informations en langue française. Italiano: «Nessun'altra valle del Canton Ticino gode di tale rinomanza e attira più visitatori della Val Piora, che al giorno d'oggi fa parte delle alte valli più conosciute d'Europa». E' così che l'Enciclopedia geografica svizzera presentava la regione nel 1905. Difatti, grazie alla sua geologia e a una ricchezza mineralogica straordinarie, i suoi antichi laghi glaciali, una flora molto diversa, e infine ai suoi magnifici alpeggi, la Valle Piora costituisce un vero paradiso e una regione prediletta per le ricerche ed escursioni naturalistiche. Ma è pure un luogo di passaggio obbligato: attraverso il Passo dell'Uomo, il Passo Columbe ed il Passo del Sole, è possibile raggiungere il Lucomagno; il Passo Predelp e il Passo Forca comunicano con la Leventina. Dalla Val Cadlimo si raggiunge il Passo dell'Oberalp, attraverso il Passo Bornengo, e, passando dalla Val Canaria, il Passo del S. Gottardo. Tra le numerose pubblicazioni che concernono la regione, possiamo menzionare la guida di escursioni edita dall'Atlas idrologico svizzero (n. 5.1), e il libretto pubblicato in occasione dell'inaugurazione del Sentiero didattico Lago Ritóm. La guida natura e ambiente qui presentata propone un'informazione scientifica semplice e alcuni itinerari che includono parzialmente i due itinerari descritti dalle due guide qui sopra menzionate e alcuni siti complementari che fanno riferimento alla geologia e alla mineralogia. Numerose pubblicazioni scientifiche sono menzionate nelle bibliografie di cui alcune possono essere consultate sul sito internet www.cadagno.ch. Questa guida dovrebbe incitare anche ricercatori e visitatori a far riferimento alla letteratura specializzata per approfondire le proprie conoscenze e colmare eventuali lacune

Piora - Lago di Cadagno - Ritom : Guide nature et environnement = Guida nature e ambiente = Natur- und Umweltführer

Le Val Piora constitue un vrai paradis et une région de prédilection pour les recherches et excursions scientifiques dans un milieu alpin exceptionnellement riche et varié. C'est pour cette raison que l'Université de Genève, associée au Centre de Biologie Alpine du Canton du Tessin et à l'Université de Zürich, y organise chaque année des stages de formation dans le cadre des cursus en sciences de l'environnement, en géologie et en biologie. Le "Guide nature et environnement" présenté ici fournit une introduction à de nombreux aspects scientifiques de la région, de la géologie à l'hydrologie, la géochimie et la microbiologie des eaux, la flore, la faune, les sols, l'histoire environnementale et l'histoire de l'économie alpestre. Le guide peut être déchargé en trois langues: français, italien, allemand. Avec des contributions de: Reiner Bachofen, Fabrizio Barudoni, Adriano Dolfini, Giorgio Guscetti, Valerio Jelmini, Enrico Krüsi, Jean-Luc Loizeau, Joëlle Massy, Yves Nardini, Raffaele Peduzzi, Sandro Peduzzi, Rodolphe Spichiger, Mauro Tonolla, Walter Wild

Piora – Lago di Cadagno – Ritom : Natur- und Umweltführer /A guide to nature and environment

Deutsch: "Kein anderes Tal im Kanton Tessin geniesst einen solchen Ruf und zieht so viele Besucher an, wie das Val Piora, das heute zu den bekanntesten Hochtälern Europas zählt." Mit diesen Worten beschreibt das Geographische Lexikon der Schweiz die Region im Jahr 1905. In der Tat, ist das Val Piora durch seine außergewöhnliche Geologie und Mineralogie, seine ehemaligen Gletscherseen, seine vielfältige Flora und seine Alpweiden, ein Paradies und eine ausgezeichnete Region für Forschung und naturkundliche Ausflüge. Das Tal ist aber auch ein wichtiger Durchgangsweg: Über den Passo dell'Uomo, den Passo Columbe und den Passo del Sole ist es möglich, den Lukmanierpass zu erreichen. Der Passo de Predelp verbindet mit der Leventina. Durch das Val Cadlimo gelangt man via Passo Bornengo zum Oberalppass, durch das Val Canaria via Unteralp- und Sellapass zum Gotthardpass. Unter den zahlreichen Veröffentlichungen zu dieser Region, sind die im Rahmen des Hydrologischen Atlas der Schweiz veröffentlichten Führer und die anlässlich der Einweihung des Lehrpfads Ritom erstellten Broschüren zu erwähnen. Der vorliegende „Natur- und Umweltführer“ bietet grundlegende wissenschaftliche Informationen und schlägt zusätzlich zu den in den oben erwähnten Schriften beschriebenen Exkursionen ergänzende Routen vor, unter besonderer Berücksichtigung geologischer und mineralogischer Themen. Zahlreiche wissenschaftliche Publikationen sind in den Bibliographien aufgelistet. Davon können einige auf der Internetsite www.cadagno.ch studiert und heruntergeladen werden. Damit möchten wir Forscher und andere interessierte Besucher einladen, zu spezifischen Fragen auch einschlägige Fachliteratur beizuziehen. English: "No other valley in the Canton of Ticino enjoys such a reputation and attracts so many visitors as Val Piora, which is now one of the best known high alpine valleys in Europe." With these words, the Geographical Dictionary of Switzerland describes the region in 1905. In fact, with its geological and mineralogical diversity, its former glacial lakes, its diverse flora and its alpine meadows, the Val Piora is a paradise and an excellent area for research and natural history studies. But the valley is also an important transit route: when crossing the Passo dell'Uomo, the Passo Columbe and the Passo del Sole it is possible to reach the Lucomagno Pass. The Passo de Predelp connects to the Leventina. Val Cadlimo leads via the Passo Bornengo to the Oberalp Pass, and through the Val Canaria one gets to the Gotthard Pass via the Unteralp- and Sellapass . Among the numerous publications dealing with this region, one has to mention the field guides published in the Hydrological Atlas of Switzerland and the guides published in relation with the didactic trail of Lago Ritom. The present “guide to nature and environment” provides basic scientific information and proposes, in addition to the excursions described in the documents mentioned above, additional routes, with special consideration to geological and mineralogical topics. Numerous scientific publications are listed in the bibliography. Some can be studied and downloaded on the internet site www.cadagno.ch. We would also like to invite scientists and interested visitors to consult other relevant literature about specific issues

Wolfgang Geiger (17 July 1921 - 3 July 2000)

Wolfgang Geiger died on the 3rd July 2000, at the age of 79. He was born on July 17th 1921 in Biel; his mother died at his birth. His childhood was spent with his father, a well-known artist, partly in Ligerz, on Lake Biel, and partly in Porto Ronco in Ticino, on Lago Maggiore. After high school in Biel, he began his University studies, first at the Swiss Federal Institute of Technology in Zürich, then in Basel, where he studied under Professor A. Portmann. During his PhD a grant from the Janggen-Pöhn foundation enabled him to work for some months at the Institut des Pêches maritimes du Maroc, in Casablanca, with Dr. J .Furnestin. In 1953 he completed his PhD on teleost fish brain. His career as a biologist began in Bern at the Eidgenossische Inspektion für Fortwesen, Jagd und Fischerei. In 1962 he was appointed head assistant (chef des travaux) at the University of Geneva, in the comparative anatomy and physiology laboratory (Dr H. J. Huggel), where he discovered the joys and the limitations of teaching. He was highly regarded as a lecturer and taught in a relaxed atmosphere of mutual respect and trust, much appreciated by his students. Professor Geiger was also the main organiser of field trips to Sète, on the French Mediterranean coast, where he was in his element living on the water. He went out on the trawlers with the students and introduced them enthusiastically to the marvels of sea fauna. He was happy during those field trips and had the knack of communicating his happiness to the students