Meteor and remote sensing satellites (a collection of articles)

Two short articles are presented that discuss satellite observation. Cloud cover interference of infrared photography is discussed. A file of the cloud cover over France is presented

Chemometric perspectives on plankton community responses to natural iron fertilisation over and downstream of the Kerguelen Plateau in the Southern Ocean

International audienceWe examined phytoplankton community responses to natural iron fertilisation at 32 sites over and downstream from the Kerguelen Plateau in the Southern Ocean during the austral spring bloom in October–November 2011. The community structure was estimated from chemical and isotopic measurements (particulate organic carbon – POC; 13C-POC; particulate nitrogen – PN; 15N-PN; and biogenic silica – BSi) on size-fractionated samples from surface waters (300, 210, 50, 20, 5, and 1 μm fractions). Higher values of 13C-POC (vs. co-located 13C values for dissolved inorganic carbon – DIC) were taken as indicative of faster growth rates and higher values of 15N-PN (vs. co-located 15N-NO3 source values) as indicative of greater nitrate use (rather than ammonium use, i.e. higher f ratios).Community responses varied in relation to both regional circulation and the advance of the bloom. Iron-fertilised waters over the plateau developed dominance by very large diatoms (50–210 μm) with high BSi / POC ratios, high growth rates, and significant ammonium recycling (lower f ratios) as biomass built up. In contrast, downstream polar frontal waters with a similar or higher iron supply were dominated by smaller diatoms (20–50 μm) and exhibited greater ammonium recycling. Stations in a deep-water bathymetrically trapped recirculation south of the polar front with lower iron levels showed the large-cell dominance observed on the plateau but much less biomass. Comparison of these communities to surface water nitrate (and silicate) depletions as a proxy for export shows that the low-biomass recirculation feature had exported similar amounts of nitrogen to the high-biomass blooms over the plateau and north of the polar front. This suggests that early spring trophodynamic and export responses differed between regions with persistent low levels vs. intermittent high levels of iron fertilisation

Reduction of Dopamine Level Enhances the Attractiveness of Male Drosophila to Other Males

Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior

The ITGAV rs3738919-C allele is associated with rheumatoid arthritis in the European Caucasian population: a family-based study

The integrin αvβ3, whose αv subunit is encoded by the ITGAV gene, plays a key role in angiogenesis. Hyperangiogenesis is involved in rheumatoid arthritis (RA) and the ITGAV gene is located in 2q31, one of the suggested RA susceptibility loci. Our aim was to test the ITGAV gene for association and linkage to RA in a family-based study from the European Caucasian population

Transcriptome Analysis Describing New Immunity and Defense Genes in Peripheral Blood Mononuclear Cells of Rheumatoid Arthritis Patients

Background: Large-scale gene expression profiling of peripheral blood mononuclear cells from Rheumatoid Arthritis (RA) patients could provide a molecular description that reflects the contribution of diverse cellular responses associated with this disease. The aim of our study was to identify peripheral blood gene expression profiles for RA patients, using Illumina technology, to gain insights into RA molecular mechanisms. Methodology/Principal Findings: The Illumina Human-6v2 Expression BeadChips were used for a complete genome-wide transcript profiling of peripheral blood mononuclear cells (PBMCs) from 18 RA patients and 15 controls. Differential analysis per gene was performed with one-way analysis of variance (ANOVA) and P values were adjusted to control the False Discovery Rate (FDR < 5%). Genes differentially expressed at significant level between patients and controls were analyzed using Gene Ontology (GO) in the PANTHER database to identify biological processes. A differentially expression of 339 Reference Sequence genes (238 down-regulated and 101 up-regulated) between the two groups was observed. We identified a remarkably elevated expression of a spectrum of genes involved in Immunity and Defense in PBMCs of RA patients compared to controls. This result is confirmed by GO analysis, suggesting that these genes could be activated systemically in RA. No significant down-regulated ontology groups were found. Microarray data were validated by real time PCR in a set of nine genes showing a high degree of correlation. Conclusions/Significance: Our study highlighted several new genes that could contribute in the identification of innovative clinical biomarkers for diagnostic procedures and therapeutic interventions

Carbon, nitrogen and phosphorus elemental stoichiometry in aquacultured and wild-caught fish and consequences for pelagic nutrient dynamics

International audienceThe elemental carbon (C), nitrogen (N) and phosphorus (P) compositions of the whole-body and gut content of wild marine fish inhabiting the Bay of Biscay (Northeast Atlantic) were studied. Furthermore, the literature was examined for studies of aquacultured fish, reporting the elemental composition of the whole-body fish, that of their food, and nutrient assimilation and gross growth efficiencies (GGE). In both wild-caught and aquacultured fish, significant differences in C, N and P elemental composition were found between species, with P being the most variable component. Differences among species in terms of C, N and P content could be explained by varying proportions of storage compounds in whole-body fish, and varying degrees of ossification. Aquacultured fish feces were found to be P-rich, because of a lower P assimilation efficiency, compared to C or N assimilation efficiencies. Examination of aquacultured fish literature also revealed that C, N and P GGE and nutrient resupply ratios agreed with basic principles of homeostatic regulation of whole-body fish elemental composition. Extrapolation of the results to broader marine systems indicated that fish may be important for conveying nutrients toward the ocean interior

Pigments, elemental composition (C, N, P, and Si), and stoichiometry of particulate matter in the naturally iron fertilized region of Kerguelen in the Southern Ocean

International audienceThe particulate matter distribution and phyto-plankton community structure of the iron-fertilized Ker-guelen region were investigated in early austral spring (October–November 2011) during the KEOPS2 cruise. The iron-fertilized region was characterized by a complex mesoscale circulation resulting in a patchy distribution of particulate matter. Integrated concentrations over 200 m ranged from 72.2 to 317.7 mg m −2 for chlorophyll a 314 to 744 mmol m −2 for biogenic silica (BSi), 1106 to 2268 mmol m −2 for particulate organic carbon, 215 to 436 mmol m −2 for particulate organic nitrogen, and 29.3 to 39.0 mmol m −2 for particulate organic phosphorus. Three distinct high biomass areas were identified: the coastal waters of Kerguelen Islands, the easternmost part of the study area in the polar front zone, and the southeastern Kergue-len Plateau. As expected from previous artificial and natural iron-fertilization experiments, the iron-fertilized areas were characterized by the development of large diatoms revealed by BSi size–fractionation and high performance liquid chromatography (HPLC) pigment signatures, whereas the iron-limited reference area was associated with a low biomass dominated by a mixed (nanoflagellates and diatoms) phy-toplankton assemblage. A major difference from most previous artificial iron fertilization studies was the observation of much higher Si : C, Si : N, and Si : P ratios (0.31 ± 0.16, 1.6 ± 0.7 and 20.5 ± 7.9, respectively) in the iron-fertilized areas compared to the iron-limited reference station (0.13, 1.1, and 5.8, respectively). A second difference is the patchy response of the elemental composition of phytoplankton communities to large scale natural iron fertilization. Comparison to the previous KEOPS1 cruise also allowed to address the seasonal dynamics of phytoplankton bloom over the southeastern plateau. From particulate organic carbon (POC), particulate organic nitrogen (PON), and BSi evolu-tions, we showed that the elemental composition of the particulate matter also varies at the seasonal scale. This temporal evolution followed changes of the phytoplankton community structure as well as major changes in the nutrient stocks progressively leading to silicic acid exhaustion at the end of the productive season. Our observations suggest that the specific response of phy-toplankton communities under natural iron fertilization is much more diverse than what has been regularly observed in artificial iron fertilization experiments and that the elemental composition of the bulk particulate matter reflects phyto-plankton taxonomic structure rather than being a direct consequence of iron availability

Seasonal evolution of net and regenerated silica production around a natural Fe-fertilized area in the Southern Ocean estimated with Si isotopic approaches

International audienceA massive diatom bloom is observed each year in the surface waters of the naturally Fe-fertilized Kerguelen Plateau (Southern Ocean). We measured biogenic silica production and dissolution fluxes (ρSi and ρDiss, respectively) in the mixed layer in the vicinity of the Kerguelen Plateau during austral spring 2011 (KEOPS-2 cruise). We compare results from a high-nutrient low-chlorophyll reference station and stations with different degrees of iron enrichment and bloom conditions. Above the plateau biogenic ρSi are among the highest reported so far in the Southern Ocean (up to 47.9 mmol m−2 d−1). Although significant (10.2 mmol m−2 d−1 on average), ρDiss were generally much lower than production rates. Uptake ratios (ρSi : ρC and ρSi : ρN) confirm that diatoms strongly dominate primary production in this area. At the bloom onset, decreasing dissolution-to-production ratios (D : P) indicate that the remineralization of silica could sustain most of the low silicon uptake and that the system progressively shifts toward a silica production regime which must be mainly supported by new source of silicic acid. Moreover, by comparing results from the two KEOPS expeditions (spring 2011 and summer 2005), we suggest that there is a seasonal evolution of the processes decoupling Si and N cycles in the area. Indeed, the consumption of H4SiO4 standing stocks occurs only during the growing stage of the bloom when strong net silica production is observed, contributing to higher H4SiO4 depletion relative to NO3−. Then, the decoupling of H4SiO4 and NO3− is mainly controlled by the more efficient nitrogen recycling relative to Si. Gross Si : N uptake ratios were higher in the Fe-rich regions compared to the high-nutrient low-chlorophyll (HNLC) area, likely due to different diatom communities. This suggests that the diatom responses to natural Fe fertilization are more complex than previously thought, and that natural iron fertilization over long timescales does not necessarily decrease Si : N uptake ratios as suggested by the silicic acid leakage hypothesis. Finally, we propose the first seasonal estimate of the Si biogeochemical budget above the Kerguelen Plateau based on direct measurements. This study points out that naturally iron-fertilized areas of the Southern Ocean could sustain very high regimes of biogenic silica production, similar to those observed in highly productive upwelling systems