Cooperation among cancer cells: applying game theory to cancer

Cell cooperation promotes many of the hallmarks of cancer via the secretion of diffusible factors that can affect cancer cells or stromal cells in the tumour microenvironment. This cooperation cannot be explained simply as the collective action of cells for the benefit of the tumour because non-cooperative subclones can constantly invade and free-ride on the diffusible factors produced by the cooperative cells. A full understanding of cooperation among the cells of a tumour requires methods and concepts from evolutionary game theory, which has been used successfully in other areas of biology to understand similar problems but has been underutilized in cancer research. Game theory can provide insights into the stability of cooperation among cells in a tumour and into the design of potentially evolution-proof therapies that disrupt this cooperation

ICAR: endoscopic skull‐base surgery

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Analytical approaches to photobiological hydrogen production in unicellular green algae

Several species of unicellular green algae, such as the model green microalga Chlamydomonas reinhardtii, can operate under either aerobic photosynthesis or anaerobic metabolism conditions. A particularly interesting metabolic condition is that of “anaerobic oxygenic photosynthesis”, whereby photosynthetically generated oxygen is consumed by the cell’s own respiration, causing anaerobiosis in the culture in the light, and induction of the cellular “hydrogen metabolism” process. The latter entails an alternative photosynthetic electron transport pathway, through the oxygen-sensitive FeFe-hydrogenase, leading to the light-dependent generation of molecular hydrogen in the chloroplast. The FeFe-hydrogenase is coupled to the reducing site of photosystem-I via ferredoxin and is employed as an electron-pressure valve, through which electrons are dissipated, thus permitting a sustained electron transport in the thylakoid membrane of photosynthesis. This hydrogen gas generating process in the cells offers testimony to the unique photosynthetic metabolism that can be found in many species of green microalgae. Moreover, it has attracted interest by the biotechnology and bioenergy sectors, as it promises utilization of green microalgae and the process of photosynthesis in renewable energy production. This article provides an overview of the principles of photobiological hydrogen production in microalgae and addresses in detail the process of induction and analysis of the hydrogen metabolism in the cells. Furthermore, methods are discussed by which the interaction of photosynthesis, respiration, cellular metabolism, and H(2) production in Chlamydomonas can be monitored and regulated

Over-the-Counter Monocyclic Non-Steroidal Anti-Inflammatory Drugs in Environment—Sources, Risks, Biodegradation

Recently, the increased use of monocyclic non-steroidal anti-inflammatory drugs has resulted in their presence in the environment. This may have potential negative effects on living organisms. The biotransformation mechanisms of monocyclic nonsteroidal anti-inflammatory drugs in the human body and in other mammals occur by hydroxylation and conjugation with glycine or glucuronic acid. Biotransformation/biodegradation of monocyclic non-steroidal anti-inflammatory drugs in the environment may be caused by fungal or bacterial microorganisms. Salicylic acid derivatives are degraded by catechol or gentisate as intermediates which are cleaved by dioxygenases. The key intermediate of the paracetamol degradation pathways is hydroquinone. Sometimes, after hydrolysis of this drug, 4- aminophenol is formed, which is a dead-end metabolite. Ibuprofen is metabolized by hydroxylation or activation with CoA, resulting in the formation of isobutylocatechol. The aim of this work is to attempt to summarize the knowledge about environmental risk connected with the presence of over-the-counter antiinflammatory drugs, their sources and the biotransformation and/or biodegradation pathways of these drugs

Pb, Zn, Cs, Sc and rare earth elements as tracers of the Loire and Gironde particles on the Biscay shelf (SW France)

The western Atlantic continental margin of the Bay of Biscay is characterised by a combined macro-tidal and a high energy environment. These conditions are responsible for the essentially sandy sedimentary cover along with well-defined fine deposit zones observed on the shelf. The main continental sources are the Loire, Gironde and Adour Rivers. It is estimated that 2.4 to 2.5 million tons of fine sediments are supplied annually to the ocean from these rivers of the French Atlantic coast. The Gironde and the Loire contribute with 84 % and the Gironde with 60 % of this amount. Previous studies of the distribution of the clay mineral assemblages and of oligo-elements have distinguished two provinces (north and south Biscay areas) according to these riverine sources. The use of an inductively coupled plasma-mass spectrometry (ICP-MS) technique allowed us to analyse both heavy metals and rare earth elements (REE), thus permitting an effective characterisation of continental sources. On the basis of these results, it has been possible to better identify the respective contributions of the Loire and the Gironde Rivers to the fine-grained sedimentation on the inner shelf.La marge continentale ouest-atlantique est un domaine macro-tidal à haut niveau d'énergie. Cette dynamique forte a mis en place sur la plate-forme du Golfe de Gascogne une couverture sédimentaire essentiellement sableuse et des zones de dépôts fins bien circonscrites. Les principales sources continentales sont la Loire, la Gironde et l'Adour. On estime que 2,4 à 2,5 millions de tonnes de sédiments fins sont issus chaque année de ces fleuves. La Gironde et la Loire contribuent pour 84 % à cet apport et la Gironde, à elle seule, pour 60 %. Des études antérieures fondées sur la répartition des cortèges de minéraux argileux ou sur celle des éléments traces ont mis en évidence des domaines nord et sud-Gascogne. L'utilisation de techniques d'analyses multi-élémentaires telles que l'ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) dosant également les terres rares, a permis une meilleure caractérisation des sources continentales girondine et ligérienne. Ces résultats permettent de préciser les domaines d'influence respectifs de la Loire et de la Gironde dans la sédimentation fine actuelle sur la plate-forme interne

Geochemical characterization of sediment cores from the continental shelf off the western rias area (NW Iberian Peninsula)

The present work aims to understand the origin of sediments deposited in the Galician coastal zone and continental shelf. Selected sediment cores were studied using different geochemical approaches: grain-size measurements, carbonate determinations and elemental analyses. Chemical analyses were carried out by multielemental techniques: energy dispersive X-ray fluorescence spectrometry (EDXRF) and instrumental neutron activation analysis (INAA). The grain-size distribution demonstrated that samples collected off the rias (Vigo and Pontevedra) contain higher percentages of silt and clay. The carbonate enrichment measured in some sediment samples with different locations and granulometries seems to indicate that the sediments might have distinct origins: biological fluvial productivity in sediments off the rias and marine biogenic activities for the deeper continental shelf sediments. Chemical analyses made it possible to distinguish different elemental sources: lithogenic, anthropogenic and biogenic. The downcore profiles of the elemental composition showed signs of a recent continental contamination for Zn and to a lesser extent for As, although there are no signs of exportation to the adjacent continental shelf. Other elements that can indicate anthropogenic activities were present in low concentrations compared with reference values. The Zr distribution determined in sediments collected along a straight line off Vigo Ria increases westwards, indicating an absence of recent exportation of this element from the continent

Le comblement de la ria de Gernika (golfe de Gascogne) à l'Holocène terminal

A study of the recent sedimentation of the ria de Gernika (Bay of Biscay) is undertaken to characterise different steps of its Holocene filling. Sedimentological and micropalaeontological analysis of six cores sampled in the ria, completed with absolute dating (C-14, and based upon Pb-210 exc.), allow us to identify three phases in the filling of the ria that are Limited by two transgressive shifts (3500 and 2500 yr. B.P.) already described in other areas of the Bay of Biscay. In the first phase, lithologies as well as benthic foraminifera and ostracode assemblages are typical of coastal marine palaeo-environment. During the second phase the euryhaline waters progessively occupy the central area of the estuary. Here the presence of allochthonous microfauna, particularly of planktonic foraminifera, indicates an increase of exchanges with marine waters that can reach the inner areas of the estuarine system. The last phase (2500 yr. B.P. to the present), which corresponds to the recent and active sedimentation, is marked by an impoverishment of the microfaunas, the filling of some channels and the increase of salt marshes. The estimated sedimentation rate for the upper decimetres of the cores (0.73-1.29 cm . yr(-1)) shows faster sedimentary filling of the ria with anthropic action evidenced by the presence of metallic contaminants and hypohaline microfauna.Une étude de la sédimentation récente de la ria de Gernika (golfe de Gascogne) est entreprise dans le but de déterminer les diverses étapes de son comblement holocène. L'analyse sédimentologique et micropaléontologique de six carottes prélevées dans la ria, complétée par des datations absolues (14C) et l'estimation de taux de sédimentation basées sur la mesure du 210Pb exc. permettent d'identifier trois épisodes dans le comblement de la ria qui correspondraient à deux pulsations transgressives (3500 et 2500 ans B.P.) déjà observées dans d'autres secteurs du golfe de Gascogne. Dans le premier épisode, les lithologies et les associations de foraminifères benthiques et d'ostracodes montrent un paléoenvironnement marin côtier. Dans le second épisode, les paléoenvironnements euryhalins gagnent progressivement la partie médiane de l'estuaire avec, au même moment, la présence de microfaunes allochtones (foraminifères planctoniques surtout) qui suggère une augmentation des échanges avec les eaux marines jusque dans la partie la plus amont du système. L'épisode 3 (2500 ans B.P. à l'actuel) correspond à une sédimentation récente toujours active; elle se traduit par un appauvrissement de la microfaune, un colmatage des chenaux et une extension de la zone de schorre. Les taux de sédimentation dans les derniers décimètres (0,73-1,29 cm/an) témoignent d'une accélération du comblement de la ria durant le dernier siècle au cours duquel l'action anthropique se manifeste par la présence de contaminants métalliques (Pb et As) et d'une faune hyposaline

Etude isotopique (Sr-Nd) de l'origine des depots fins holocenes du littoral atlantique (S-O France)

The fine-grained sediments of the West Gironde mud patch derive mainly from materials supplied via the Gironde estuary. Between 1500 and 1200/1300 years BP and 300/400 years BP and the present day, the Sr isotopic and chemical compositions of the estuarine silty clay inputs are the same. In contrast, these compositions were different during the period 1200/1300 to 300/400 years BP These variations probably reflect anthropogenic activities including cultivation and agriculture, in the Garonne and Dordogne drainage basins during the medieval period. Modern silty clay sedimentation in the mud flats of the Marennes-Oleron basin and Perthuis Breton is characterised by the occurrence of important quantities (between 40 and 90 % of the total) of detritus that issues from the Gironde estuary. The autochthonous silty clays derived from outcrops of Jurassic green marls and Flandrian deposits are mixed with estuarine allochthonous clays delivered by coastal surface currents. In the Anse de l'Aiguillon, the muds are mainly composed of these autochthonous silty clays. The silty clay infilling of these mud flats has been highly influenced by the development of the oyster and shellfish aquaculture.La sédimentation fine de la vasiére Ouest-Gironde a essentiellement été alimentée par des matériaux provenant de l'estuaire de la Gironde. Si la signature isotopique et chimique (Sr) des apports silty-argileux estuariens a été la même pendant les périodes 1500 ans BP - 1300/1400 ans BP et 300/400 ans BP - actuel, elle présente, au contraire, des variations importantes pendant toute la période allant de 1200/1300 ans BP à 300/400 ans BP. Ces changements sédimentaires sont probablement à reliet à des actions anthropiques, défrichements et agriculture, dans les bassins versants de la Garonne et de la Dordogne de la période médiévale. La sédimentation silto-argileuse actuelle des slikkes du bassin de Marennes-Oléron et du perthuis Breton est caractérisée par la présence, souvent en quantité importante (entre 40 et 90 %), de matériaux provenant de l'estuaire de la Gironde; à ces matériaux allochtones véhiculés par les courants de surface se mélangent des argiles silteuses autochtones issues des formations affleurantes de marnes grises jurassiques et/ou de dépôts flandriens. Dans l'anse de l'Aiguillon, les vases sont composées essentiellement de ces argiles silteuses autochtones. Le colmatage silto-argileux de ces slikkes a été fortement favorisé par l'homme avec le développement de l'ostréiculture et de la conchyliculture

Some evidences of northward fine sediment transport in the northern Portuguese continental shelf

On the basis of sedimentological and oceanographical data, a transport scheme for fine-grained material is proposed in order to explain the location of a muddy deposit present in the northern Portuguese continental shelf, north-west off the Douro River mouth. This mid-shelf deposit is recent, active and its main source is apparently the Douro River. The sediment supply can be related with the oceanographic conditions in winter regime, characterised by a poleward along shelf current with a bottom westward component, as a consequence of a south-west wind. The resulting fine sediment transport, essentially made in the bottom nepheloid layer is believed to have a north-west direction.Un schéma de circulation des sédiments fins, sur le plateau continental au nord du Portugal, a été établi à partir de données sédimentologiques et océanographiques. Il explique la présence d'une vasière située au nord-ouest de l'embouchure du Douro; ce dépôt récent et actif proviendrait essentiellement du fleuve. L'apport de sédiment est lié aux conditions hydrologiques hivernales, caractérisées par un courant dirigé vers le nord le long du plateau continental avec, au fond, une composante vers l'ouest due au vent du sud-ouest. Il en résulte que le transport des sédiments fins se fait principalement dans la couche néphéloïde de fond, en direction du nord-ouest