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Palm seed and fruit lipid composition : phylogenetic and ecological perspectives
No full textBackground and aims - Palms are vital to worldwide human nutrition, in particular as major sources of vege-table oils. However, our knowledge of seed and fruit lipid diversity in the family Arecaceae is limited. We therefore aimed to explore relationships between seed and fruit lipid content, fatty acid composition in the respective tissues, phylogenetic factors and biogeographical parameters.
Methods - Oil content and fatty acid composition were characterized in seeds and fruits of 174 and 144 palmspecies respectively. Distribution, linear regression and multivariate analyses allowed an evaluation of the chemotaxonomic value of these traits and their potential relationship with ecological factors.
Key Results - A considerable intra-family diversity for lipid traits was revealed. Species with the most lipid-richseeds belonged to the tribe Cocoseae, while species accumulating oil in the mesocarp occurred in all subfamilies and two-thirds of the tribes studied. Seed and fruit lipid contents were not correlated. Fatty acid composition of mesocarp oil was highly variable within tribes. By contrast, within-tribe diversity for seed lipid traits was low, whereas between-tribe variability was high. Consequently, multivariate analyses of seed lipid traits produced groupings of species belonging to the same tribe. Medium-chain fatty acids predominated in seeds of most palm species, but they were also accumulated in the mesocarp in some cases. Seed unsaturated fatty acid content correl-ated with temperature at the coldest latitude of natural occurrence.
Conclusion - Several previously uncharacterized palms were identified as potential new sources of vegetable oils for comestible or non-food use. Seed lipid traits reflect genetic drift that occurred during the radiation of the family and therefore are highly relevant to palm chemotaxonomy. Our data also suggest that seed unsaturated fatty acids may provide an adaptive advantage in the coldest environments colonized by palms by maintaining storage lipids in liquid form for efficient mobilization during germination
The Amazonian dwarf cichlid Apistogramma agassizii (Steindachner, 1875) is a geographic mosaic of potentially tens of species : conservation implications
No full textAssessing biodiversity and understanding how it works is a prerequisite for species conservation. The Amazon basin is one of the main biodiversity hotspots where fish are heavily exploited for ornamental purposes. The ornamental trade heavily exploits the genusApistogramma, which is one of the most species-rich among Neotropical cichlids with 94 formally described species. This number is certainly underestimated owing to the limitations of conventional taxonomy, which is still too often based solely on morphological criteria and sometimes on few individuals. Most species of this genus have a high degree of endemism and are highly prized on the ornamental market, which could put them at risk. A few species are supposed to have extensive distributions, and in particularApistogramma agassizii, present from the Amazon estuary up to the Ucayali and Maranon rivers in Peru. This study assessed the taxonomic status of 1,151 specimens ofA. agassiziicollected from 35 sites around Iquitos in the Peruvian Amazon. On the basis of molecular analyses (nuclear and mitochondrial DNA) and mate choice experiments, at least three biological species within the nominalA. agassiziiwere evidenced in the sampling area, which is extremely small compared with the known distribution of the species as initially described. According to the molecular calibrations, these three species would have diverged during the Plio-Pleistocene. Two of them seem to be endemic from small sub-basins, one from the Nanay River and the other from the Apayacu/Ampiyacu systems. A possible scenario that may explain the evolutionary history of these species is proposed. The conservation implications of these results on the estimation of the diversity ofA. agassizii, ofApistogrammaspecies in general, and of other Amazonian cichlids are discussed
Bio-physical coupling around three shallow seamounts in the South Western Indian Ocean, with regional comparisons based on modelling, remote sensing and observational studies
No full textAn investigation of the vertical and horizontal distributions of micronekton, as influenced by mesoscale eddies, the Madagascar shelf and shallow seamounts, was undertaken using acoustic data collected during two research cruises at an unnamed pinnacle (summit depth similar to 240 m) thereafter named "MAD-Ridge", and at La Perouse seamount (similar to 60 m) in the south-western Indian Ocean. MAD-Ridge is located to the south of Madagascar, in an "eddy corridor", known both for its high mesoscale activity and high primary productivity. In contrast, La Perouse is located on the outskirts of the Indian South Subtropical Gyre (ISSG) province, characterised by low mesoscale activity and low primary productivity. During the MAD-Ridge cruise, a dipole was located in the vicinity of the seamount, with the anticyclone being almost stationary on the pinnacle. Total micronekton acoustic densities were greater at MAD-Ridge than at La Perouse. Micronekton acoustic densities of the total water column were lower within the anticyclone than within the cyclone during MAD-Ridge. Micronekton followed the usual diel vertical migration (DVM) pattern, except within the cyclone during MAD-Ridge where greater acoustic densities were recorded in the daytime surface layer. The backscatter intensities were stronger at the 38 kHz than at the 70 and 120 kHz frequencies in the daytime surface layer at MAD-Ridge cyclonic stations. These backscatter intensities likely correspond to gas-filled swimbladders of epi- and mesopelagic fish actively swimming and feeding within the cyclone or gelatinous organisms with gas inclusions. Our findings evidenced that the distributions of micronekton and DVM patterns are complex and are influenced significantly by physical processes within mesoscale eddies. The mesoscale eddies' effects were dominant over any potential seamount effects at the highly dynamic environment prevailing at MAD-Ridge during the cruise. No significant increase in total micronekton acoustic densities was observed over either seamount, but dense aggregations of biological scatterers were observed on their summits during both day and night
Wide cross-species RNA-Seq comparison reveals convergent molecular mechanisms involved in nickel hyperaccumulation across dicotyledons
No full textThe Anthropocene epoch is associated with the spreading of metals in the environment increasing oxidative and genotoxic stress on organisms. Interestingly,c. 520 plant species growing on metalliferous soils acquired the capacity to accumulate and tolerate a tremendous amount of nickel in their shoots. The wide phylogenetic distribution of these species suggests that nickel hyperaccumulation evolved multiple times independently. However, the exact nature of these mechanisms and whether they have been recruited convergently in distant species is not known. To address these questions, we have developed a cross-species RNA-Seq approach combining differential gene expression analysis and cluster of orthologous group annotation to identify genes linked to nickel hyperaccumulation in distant plant families. Our analysis reveals candidate orthologous genes encoding convergent function involved in nickel hyperaccumulation, including the biosynthesis of specialized metabolites and cell wall organization. Our data also point out that the high expression of IREG/Ferroportin transporters recurrently emerged as a mechanism involved in nickel hyperaccumulation in plants. We further provide genetic evidence in the hyperaccumulatorNoccaea caerulescensfor the role of the NcIREG2 transporter in nickel sequestration in vacuoles. Our results provide molecular tools to better understand the mechanisms of nickel hyperaccumulation and study their evolution in plants
Review on observational studies of western tropical Pacific Ocean circulation and climate
No full textThe Western Tropical Pacific (WTP) Ocean holds the largest area of warm water (>28 degrees C) in the world ocean referred to as the Western Pacific Warm Pool (WPWP), which modulates the regional and global climate through strong atmospheric convection and its variability. The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability, making it crucial in the water and energy cycle of the global ocean. Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960s through field experiments. In this study, we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades, with emphasis on the achievements since 2000. The challenges and open questions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate
Ruby deposits : a review and geological classification
No full textCorundum is not uncommon on Earth but the gem varieties of ruby and sapphire are relatively rare. Gem corundum deposits are classified as primary and secondary deposits. Primary deposits contain corundum either in the rocks where it crystallized or as xenocrysts and xenoliths carried by magmas to the Earth's surface. Classification systems for corundum deposits are based on different mineralogical and geological features. An up-to-date classification scheme for ruby deposits is described in the present paper. Ruby forms in mafic or felsic geological environments, or in metamorphosed carbonate platforms but it is always associated with rocks depleted in silica and enriched in alumina. Two major geological environments are favorable for the presence of ruby: (1) amphibolite to medium pressure granulite facies metamorphic belts and (2) alkaline basaltic volcanism in continental rifting environments. Primary ruby deposits formed from the Archean (2.71 Ga) in Greenland to the Pliocene (5 Ma) in Nepal. Secondary ruby deposits have formed at various times from the erosion of metamorphic belts (since the Precambrian) and alkali basalts (from the Cenozoic to the Quaternary). Primary ruby deposits are subdivided into two types based on their geological environment of formation: (Type I) magmatic-related and (Type II) metamorphic-related. Type I is characterized by two sub-types, specifically Type IA where xenocrysts or xenoliths of gem ruby of metamorphic (sometimes magmatic) origin are hosted by alkali basalts (Madagascar and others), and Type IB corresponding to xenocrysts of ruby in kimberlite (Democratic Republic of Congo). Type II also has two sub-types; metamorphic deposits sensu stricto (Type IIA) that formed in amphibolite to granulite facies environments, and metamorphic-metasomatic deposits (Type IIB) formed via high fluid-rock interaction and metasomatism. Secondary ruby deposits, i.e., placers are termed sedimentary-related (Type III). These placers are hosted in sedimentary rocks (soil, rudite, arenite, and silt) that formed via erosion, gravity effect, mechanical transport, and sedimentation along slopes or basins related to neotectonic motions and deformation
Preliminary investigation of the relationship between differential phase shift and path-integrated attenuation at the X band frequency in an Alpine environment
No full textThe RadAlp experiment aims at developing advanced methods for rainfall and snowfall estimation using weather radar remote sensing techniques in high mountain regions for improved water resource assessment and hydrological risk mitigation. A unique observation system has been deployed since 2016 in the Grenoble region of France. It is composed of an X-band radar operated by Meteo-France on top of the Moucherotte mountain (1901m above sea level; hereinafter MOUC radar). In the Grenoble valley (220m above sea level; hereinafter a.s.l.), we operate a research X-band radar called XPORT and in situ sensors (weather station, rain gauge and disdrometer). In this paper we present a methodology for studying the relationship between the differential phase shift due to propagation in precipitation (Phi(dp)) and path-integrated attenuation (PIA) at X band. This relationship is critical for quantitative precipitation estimation (QPE) based on polarimetry due to severe attenuation effects in rain at the considered frequency. Furthermore, this relationship is still poorly documented in the melting layer (ML) due to the complexity of the hydrometeors' distributions in terms of size, shape and density. The available observation system offers promising features to improve this understanding and to subsequently better process the radar observations in the ML. We use the mountain reference technique (MRT) for direct PIA estimations associated with the decrease in returns from mountain targets during precipitation events. The polarimetric PIA estimations are based on the regularization of the profiles of the total differential phase shift (Psi(dp)) from which the profiles of the specific differential phase shift on propagation (K-dp) are derived. This is followed by the application of relationships between the specific attenuation (k) and the specific differential phase shift. Such k-K-dp relationships are estimated for rain by using drop size distribution (DSD) measurements available at ground level. Two sets of precipitation events are considered in this preliminary study, namely (i) nine convective cases with high rain rates which allow us to study the phi(dp)-PIA relationship in rain, and (ii) a stratiform case with moderate rain rates, for which the melting layer (ML) rose up from about 1000 up to 2500ma.s.l., where we were able to perform a horizontal scanning of the ML with the MOUC radar and a detailed analysis of the phi(dp)-PIA relationship in the various layers of the ML. A common methodology was developed for the two configurations with some specific parameterizations. The various sources of error affecting the two PIA estimators are discussed, namely the stability of the dry weather mountain reference targets, radome attenuation, noise of the total differential phase shift profiles, contamination due to the differential phase shift on backscatter and relevance of the k-K-dp relationship derived from DSD measurements, etc. In the end, the rain case study indicates that the relationship between MRT-derived PIAs and polarimetry-derived PIAs presents an overall coherence but quite a considerable dispersion (explained variance of 0.77). Interestingly, the nonlinear k-K-dp relationship derived from independent DSD measurements yields almost unbiased PIA estimates. For the stratiform case, clear signatures of the MRT-derived PIAs, the corresponding phi(dp) value and their ratio are evidenced within the ML. In particular, the averaged PIA/phi(dp) ratio, a proxy for the slope of a linear k-K-dp relationship in the ML, peaks at the level of the copolar correlation coefficient (rho(hv)) peak, just below the reflectivity peak, with a value of about 0.42 dB per degree. Its value in rain below the ML is 0.33 dB per degree, which is in rather good agreement with the slope of the linear k-K-dp relationship derived from DSD measurements at ground level. The PIA/phi(dp) ratio remains quite high in the upper part of the ML, between 0.32 and 0.38 dB per degree, before tending towards 0 above the ML
Effect of pelagic longline bait type on species selectivity : a global synthesis of evidence
No full textFisheries can profoundly affect bycatch species with 'slow' life history traits. Managing bait type offers one tool to control species selectivity. Different species and sizes of marine predators have different prey, and hence bait, preferences. This preference is a function of a bait's chemical, visual, acoustic and textural characteristics and size, and for seabirds the effect on hook sink rate is also important. We conducted a global meta-analysis of existing estimates of the relative risk of capture on different pelagic longline baits. We applied a Bayesian random effects meta-analytic regression modelling approach to estimate overall expected bait-specific catch rates. For blue shark and marine turtles, there were 34% (95% HDI: 4-59%) and 60% (95% HDI: 44-76%) significantly lower relative risks of capture on forage fish bait than squid bait, respectively. Overall estimates of bait-specific relative risk were not significantly different for seven other assessed taxa. The lack of a significant overall estimate of relative capture risk for pelagic shark species combined but significant effect for blue sharks suggests there is species-specific variability in bait-specific catch risk within this group. A qualitative literature review suggests that tunas and istiophorid billfishes may have higher catch rates on squid than fish bait, which conflicts with reducing marine turtle and blue shark catch rates. The findings from this synthesis of quantitative and qualitative evidence support identifying economically viable bycatch management measures with acceptable tradeoffs when multispecies conflicts are unavoidable, and highlight research priorities for global pelagic longline fisheries
The impact of daily soap use in rural areas of Senegal on respiratory infectious diseases, fevers and skin microbiota
No full textObjectives: Children aged <5 years are the group most affected by infectious diseases, more specifically in underdeveloped countries. A study was performed to assess the effects of daily soap use on the incidence of diarrhoea, fever, respiratory infection, and the prevalence of pathogenic bacteria on the skin. Methods: Soap was distributed to the population of the village of Ndiop (test) for use in their daily hygiene but not to the population of the village of Dielmo (control). Fieldworkers daily recorded the clinical events in the two villages and encouraged the use of soap in Ndiop. Results: A total of 638 people participated in the study. The incidence rates of cough, runny nose and fever significantly decreased in 2016 compared with 2015, unlike that of diarrhoea. In 2016, significant reductions in the incidence rates of cough, runny nose and fever were observed in children aged <15 years in Ndiop. The prevalence of Streptococcus pneumoniae, Staphylococcus aureus and Streptococcus pyogenes in the palms of the hands significantly dropped in Ndiop. Conclusion: Using soap reduces the incidence of respiratory infections, fevers and the prevalence of pathogenic bacteria on the skin. However, for diarrhoea, additional strategies are needed to improve outcomes