Subcellular investigation of photosynthesis-driven carbon assimilation in the symbiotic reef coral Pocillopora damicornis.

Reef-building corals form essential, mutualistic endosymbiotic associations with photosynthetic Symbiodinium dinoflagellates, providing their animal host partner with photosynthetically derived nutrients that allow the coral to thrive in oligotrophic waters. However, little is known about the dynamics of these nutritional interactions at the (sub)cellular level. Here, we visualize with submicrometer spatial resolution the carbon and nitrogen fluxes in the intact coral-dinoflagellate association from the reef coral Pocillopora damicornis by combining nanoscale secondary ion mass spectrometry (NanoSIMS) and transmission electron microscopy with pulse-chase isotopic labeling using [(13)C]bicarbonate and [(15)N]nitrate. This allows us to observe that (i) through light-driven photosynthesis, dinoflagellates rapidly assimilate inorganic bicarbonate and nitrate, temporarily storing carbon within lipid droplets and starch granules for remobilization in nighttime, along with carbon and nitrogen incorporation into other subcellular compartments for dinoflagellate growth and maintenance, (ii) carbon-containing photosynthates are translocated to all four coral tissue layers, where they accumulate after only 15 min in coral lipid droplets from the oral gastroderm and within 6 h in glycogen granules from the oral epiderm, and (iii) the translocation of nitrogen-containing photosynthates is delayed by 3 h. IMPORTANCE: Our results provide detailed in situ subcellular visualization of the fate of photosynthesis-derived carbon and nitrogen in the coral-dinoflagellate endosymbiosis. We directly demonstrate that lipid droplets and glycogen granules in the coral tissue are sinks for translocated carbon photosynthates by dinoflagellates and confirm their key role in the trophic interactions within the coral-dinoflagellate association.

Salvage Regimen With Autologous Stem Cell Transplantation With Or Without Rituximab Maintenance For Relapsed Diffuse Large B-Cell Lymphoma (Dlbcl): Coral Final Report

Times Cited: 0 References: 0 Citation MapAbstract : Background: Chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard treatment for relapsed DLBCL. No study has compared salvage therapies and evaluated maintenance post ASCT.Methods: DLBCL CD 20+ in first relapse or pts refractory after first therapy were randomized between R ICE (rituximab, ifosfamide, etoposide, carboplatinum) or R DHAP (rituximab dexamethasone cytarabine cisplatinum). Responding patients received BEAM and ASCT then randomized between observation or maintenance with rituximab every 2 m for 1 yr (Gisselbrecht J Clin Oncol; 2010).Results: Analysis was made on 477 pts (R ICE: 243 pts; R DHAP: 234 pts): 255 relapses >12m, 213 refractory/early relapses; 306 pts had prior rituximab; secondary(s) IPI 0-1: 281 pts; s IPI 2-3:181pts. There was no difference in response rate between R ICE 63.6% and R DHAP 64.3%. There was no difference between R ICE and R DHAP at 4 yrs for EFS (26% vs 37% p=0.2) and OS (43% vs 51%, p=0.3). Factors affecting 4 yrs EFS, PFS and OS were: prior treatment with rituximab; early relapse< 12 m; s IPI 2-3. ASCT was performed in 255 pts and 242 randomized for maintenance: 122 pts rituximab (R), 120 pts observation (O). Distribution between R/O arms were respectively: median age 54 /53 yrs, Male 76/83; female 46/37; secondary IPI 0-1: 84/81; sIPI 2-3: 36/36. 89/76 relapses >12m., 33/41 refractory/early relapses. Median follow up was 44 m with 111 events. 4 yrs EFS was 52.8 % (CI 46-59) with 63% (CI 56-69) OS. There was no difference in EFS, PFS and OS between R and O arms. In multivariate analysis, sIPI2-3 significantly affected EFS, PFS, OS (p=0.0004). Women (83pts) had a better 4 yrs EFS 63% than male (159pts) 37% (p=0.01). The difference was only in the R arm (p=0.004). Gender was an independent prognostic factor in the R arm. Toxicity was mild with 12% SAE versus 4% for R /O respectively.Conclusions: There was no difference between R ICE and R DHAP and between post ASCT maintenance with R or O. Women did significantly better after ASCT with rituximab. Early relapses to upfront rituximab-based chemotherapy have a poor prognosis.

Effects of season, sex and body size on the feeding ecology of turtle-headed seasnakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs

In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape-limitation - and hence, are most common in species that feed on relatively large prey, and exhibit a wide body-size range. Our data on seasnakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed seasnakes (Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic-stage specialization, the prey come from a taxonomically diverse array of species including damselfish (41% of samples, at least 5 species), blennies (41%, 4 species) and gobies (19%, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female seasnakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate-searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral-reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these seasnakes, by mechanisms different from those that apply to terrestrial snakes.

Quaternary coral reef refugia preserved fish diversity.

The most prominent pattern in global marine biogeography is the biodiversity peak in the Indo-Australian Archipelago. Yet the processes that underpin this pattern are still actively debated. By reconstructing global marine paleoenvironments over the past 3 million years on the basis of sediment cores, we assessed the extent to which Quaternary climate fluctuations can explain global variation in current reef fish richness. Comparing global historical coral reef habitat availability with the present-day distribution of 6316 reef fish species, we find that distance from stable coral reef habitats during historical periods of habitat loss explains 62% of the variation in fish richness, outweighing present-day environmental factors. Our results highlight the importance of habitat persistence during periods of climate change for preserving marine biodiversity.

Hybridisation and diversification in the adaptive radiation of clownfishes.

BackgroundThe importance of hybridisation during species diversification has long been debated among evolutionary biologists. It is increasingly recognised that hybridisation events occurred during the evolutionary history of numerous species, especially during the early stages of adaptive radiation. We study the effect of hybridisation on diversification in the clownfishes, a clade of coral reef fish that diversified through an adaptive radiation process. While two species of clownfish are likely to have been described from hybrid specimens, the occurrence and effect of hybridisation on the clade diversification is yet unknown.ResultsWe generate sequences of three mitochondrial genes to complete an existing dataset of nuclear sequences and document cytonuclear discordance at a node, which shows a drastic increase of diversification rate. Then, using a tree-based jack-knife method, we identify clownfish species likely stemming from hybridisation events. Finally, we use molecular cloning and identify the putative parental species of four clownfish specimens that display the morphological characteristics of hybrids.ConclusionsOur results show that consistently with the syngameon hypothesis, hybridisation events are linked with a burst of diversification in the clownfishes. Moreover, several recently diverged clownfish lineages likely originated through hybridisation, which indicates that diversification, catalysed by hybridisation events, may still be happening.

The radiation of the clownfishes has two geographical replicates

AimThe study of adaptive radiations provides an evolutionary perspective on the interactions between organisms and their environment, and is necessary to understand global biodiversity. Adaptive radiations can sometimes be replicated over several disjunct geographical entities, but most examples are found on island or in lakes. Here, we investigated the biogeographical history of the clownfishes, a clade of coral reef fish with ranges that now span most of the Indo-Pacific Ocean, in order to explore the geographical structure of an unusual adaptive radiation. LocationIndian Ocean, Indo-Australian Archipelago (IAA) and Central Pacific Ocean. MethodsWe generated DNA sequence data comprising seven nuclear markers for 27 of the 30 clownfish species. We then inferred a Bayesian phylogeny and reconstructed the biogeographical history of the group using three different methods. Finally, we applied a biogeographical model of diversification to assess whether diversification patterns differ between the Indian and Pacific Oceans. ResultsThe phylogenetic tree is highly supported and allows reconstruction of the biogeographical history of the clade. While most species arose in the IAA, one clade colonized the eastern shores of Africa and diversified there. We found that the diversification rate of clownfishes does not differ between the main radiation and the African clade. Main conclusionsThe clownfishes first appeared and diversified in the IAA. Following a colonization event, a geographically independent radiation occurred in the Indian Ocean off East Africa. This rare example of replicated adaptive radiation in the marine realm provides intriguing possibilities for further research on ecological speciation in the sea.

Trophic specialization influences the rate of environmental niche evolution in damselfishes (Pomacentridae).

The rate of environmental niche evolution describes the capability of species to explore the available environmental space and is known to vary among species owing to lineage-specific factors. Trophic specialization is a main force driving species evolution and is responsible for classical examples of adaptive radiations in fishes. We investigate the effect of trophic specialization on the rate of environmental niche evolution in the damselfish, Pomacentridae, which is an important family of tropical reef fishes. First, phylogenetic niche conservatism is not detected in the family using a standard test of phylogenetic signal, and we demonstrate that the environmental niches of damselfishes that differ in trophic specialization are not equivalent while they still overlap at their mean values. Second, we estimate the relative rates of niche evolution on the phylogenetic tree and show the heterogeneity among rates of environmental niche evolution of the three trophic groups. We suggest that behavioural characteristics related to trophic specialization can constrain the evolution of the environmental niche and lead to conserved niches in specialist lineages. Our results show the extent of influence of several traits on the evolution of the environmental niche and shed new light on the evolution of damselfishes, which is a key lineage in current efforts to conserve biodiversity in coral reefs.

Trait decoupling promotes evolutionary diversification of the trophic and acoustic system of damselfishes.

Trait decoupling, wherein evolutionary release of constraints permits specialization of formerly integrated structures, represents a major conceptual framework for interpreting patterns of organismal diversity. However, few empirical tests of this hypothesis exist. A central prediction, that the tempo of morphological evolution and ecological diversification should increase following decoupling events, remains inadequately tested. In damselfishes (Pomacentridae), a ceratomandibular ligament links the hyoid bar and lower jaws, coupling two main morphofunctional units directly involved in both feeding and sound production. Here, we test the decoupling hypothesis by examining the evolutionary consequences of the loss of the ceratomandibular ligament in multiple damselfish lineages. As predicted, we find that rates of morphological evolution of trophic structures increased following the loss of the ligament. However, this increase in evolutionary rate is not associated with an increase in trophic breadth, but rather with morphofunctional specialization for the capture of zooplanktonic prey. Lineages lacking the ceratomandibular ligament also shows different acoustic signals (i.e. higher variation of pulse periods) from others, resulting in an increase of the acoustic diversity across the family. Our results support the idea that trait decoupling can increase morphological and behavioural diversity through increased specialization rather than the generation of novel ecotypes.

Blockade of the Renin-Angiotensin system in hypertensive patients with atherosclerotic renal artery stenosis.

Renin angiotensin system (RAS) blockers are generally considered as contraindicated when an atheromatous renal artery stenosis (ARAS) is diagnosed. The main reason is the fear of inducing renal ischemia and, hence, accelerating renal fibrosis and the progression towards end stage renal disease, albeit RAS blocker have been shown to be highly effective in controlling blood pressure. Part of the solution came by the development of the revascularization. There is now growing evidence showing no superiority of angioplasty over medical treatment on cardiovascular events and mortality, renal function and blood pressure control. Hence, RAS blockers resurfaced based on their proven beneficial effects on blood pressure control and cardiovascular prevention in high risk atherosclerotic patients. Thus, RAS blockers belong today to the standard treatment of hypertensive patients with ARAS. However they were not systematically prescribed in trials focusing on ARAS. The ongoing CORAL trial will give us further information on the place of this class of antihypertensive drugs in patients with ARAS.

La spéciation écologique racontée au travers de l'étude de l'évolution des poissons-clowns et de quelques autres

Ecological speciation and its hallmark, adaptive radiation is a process from which most of the current biodiversity derives. As ecological opportunity allows species to colonise unoccupied niches, natural selection drives adaptive phenotypical change. In this thesis, I begin by describing how this evolutionary process acted on the evolution of the clownfishes. During its infancy, this iconic group of coral reef fishes developed a mutualism with sea anemone species. I show how this event triggered the evolutionary radiation of the group, generating species that now inhabit diverse habitats of the coral reefs. Following the appearance of the mutualism, the diversification of the clownfish was catalysed by hybridisation events which shuffled genes, allowing hybrids to reach new fitness optima. While the clownfishes appeared in the region of the coral triangle, a lineage colonised the eastern shores of Africa. I reconstructed the geographic history of the group and showed that this event lead to the rapid appearance of new species, replicating the evolutionary patterns of the original radiation. To better grasp the mechanisms of ecological speciation, I conducted analyses at the population level and identified similar evolutionary patterns than found at the clade level. I discuss how such result suggests a continuity bridging micro- and macroevolution, which so far only been theorised. In parallel to this study case, I question whether biotic and abiotic interactions can promote or restrain ecological speciation. Indeed, I show how the ecological setting of species can drastically impact on their diversification dynamics. Moreover, tradeoffs can occur between specialisation made on different ecological axes allowing species cohabitation. Overall, I show in this work that regardless of the few simple rules that explain the mechanism of ecological speciation, the unavoidable interactions with the ever changing ecological context lead diversification events to give always a different outcome. It is thus primordial to account for the ecological settings of species when discussing their evolutionary dynamics. LA SPÉCIATION ÉCOLOGIQUE RACONTÉE AU TRAVERS DE L'ÉTUDE DE L'ÉVOLUTION DES POISSONS-CLOWNS ET DE QUELQUES AUTRES Le phénomène de spéciation écologique est à l'origine de la majeure partie de la biodiversité que l'on rencontre aujourd'hui. Au fil des opportunités qu'elles rencontrent, les espèces colonisent l'espace écologique laissant la sélection naturelle forger leur phénotype moyen. Malgré l'omniprésence de ce phénomène dans la nature, beaucoup de questions qui lui sont relatives restent à élucider. C'est afin de mieux comprendre ce mécanisme que j'étudie les poissons-clowns, célèbres habitants des récifs coralliens. Dans ce travail, je démontré que le développement du comportement mutualiste liant les poissons-clowns aux anémones de mer fut l'événement qui déclencha leur diversification. Suite à ce premier événement, j'illustre comment l'hybridation entre lignées primordiales a remodelé la diversité génétique du groupe et catalysé leur radiation évolutive. Je poursuis en reconstruisant l'expansion géographique des poissons-clowns au cours du temps depuis le triangle de corail, leur lieu d'origine, jusqu'aux côtes d'Afrique de l'Ouest. Afin d'affiner ces analyses générales sur le groupe, je continue en étudiant plus finement des populations d'une seule espèce de poisson-clown. Cette fine résolution me permet de comprendre plus précisément quels sont les facteurs écologiques qui permettent aux poissons-clowns de se différencier. Les résultats de ces analyses suggèrent qu'il est important de comprendre les liens entre le contexte écologique et la diversification des espèces. J'étudie cette question dans la seconde partie de ce travail en montrant que l'hétérogénéité du paysage ou les liens entretenus avec un partenaire mutualiste influencent fortement la dynamique évolutive des espèces. Finalement, j'illustre les compromis que chaque espèce réalise en se spécialisant ou non dans ses interactions avec l'environnent. Plus généralement, je souligne dans ce travail l'influence du contexte écologique sur le résultat de la spéciation écologique. Ce sont ces interactions entre les organismes et leur environnent qui sont à l'origine de l'incroyable diversité de la vie. Il est donc primordial de les prendre en compte lors de l'étude de l'évolution des espèces.

Community replacement of neritic carbonate organisms during the late Valanginian platform demise: A new record from the Provence Platform

The Valanginian is marked by a major platform demise inducing a hiatus in the northern Tethyan neritic carbonate record from the top of the lower Valanginian to the lower Hauterivian. New biostratigraphic and chemostratigraphic data from the Ollioules section (Provence Platform, southern France) are presented here, demonstrating that a large part of the upper Valanginian is preserved in an inner platform environment. The thick, upper Valanginian, aggrading carbonate succession is observed in an aborted rift domain, implying relatively low subsidence. In this context, a relatively long-term sea-level rise was required to sustain a keep-up style of carbonate production. Like the Apulian Platform, the remarkable preservation of the Provence Platform may have been favored by its remoteness from terrigenous source areas, as suggested by the low clastic inputs and low P-accumulation rates. Two main biotic community replacements are observed in Ollioules. The first saw the development of abundant microbialites and algae at the onset of the late Valanginian. A Tubiphytes concentration occurred during the coolest climatic conditions and the transition towards arid conditions, whereas the subsequent Lithocodium-Bacinella and orbitolinids assemblages developed under low nutrient conditions during a warmer interval. Both assemblages may have been triggered by increased alkalinity. The second community replacement saw the installation of coral- and rudist-dominated communities during the latest Valanginian to early Hauterivian. They indicate a change to oligotrophic, open marine conditions. Six medium-scale sequences have been defined in Ollioules, indicating short-term transgressive-regressive trends superimposed on a long-term transgression. Low nutrient inputs and relatively low subsidence in an aggradational context may explain the survival of the isolated Provence Carbonate Platform during a time of widespread drowning episodes and platform demise in the northern Tethyan domain. (c) 2012 Elsevier B.V. All rights reserved.