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Cowpea [Vigna unguiculata (L.) Walp.] maternal lineages, chloroplast captures, and wild cowpea evolution
No full textVigna unguiculata is the major grain legume in Africa and is also important in South-East Asia as a vegetable. The wild relatives, present only in Africa, are currently made of ten subspecies. However, while the different groups are well identified, the relationships between them are not firmly established. The present study of chloroplast diversity through restriction fragment length polymorphism confirms the different groups, as well as the split between savannah subspecies and forest subspecies. It justifies treating subsp. stenophylla as a subspecies independent from subsp. protracta and invalidates the subsp. stenophylla sensu lato concept. It suggests that the species V. unguiculata originated in southern Africa and that the annual subsp. unguiculata var. spontanea originated in eastern Africa. More importantly, it proves that three subspecies are of hybrid origin, between the annual var. spontanea and various perennial subspecies from southern Africa with left-twisted keel. Owing to its annual and inbred properties, var. spontanea spread across all African low- to medium-altitude savannahs, displacing the left-twisted keel savannah perennials from their warmer and drier areas
Rapport d'activités 2020 - Institut de recherche pour le développement : face aux défis globaux, la science des solutions durables
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International science foresight workshop : global challenges and research gaps : the Royaumont process
No full textIntrinsic timescales of variability in a marine plankton model
No full textPhytoplankton are known to exhibit temporal variability in biomass and community composition. While physically driven sources of variability have been studied extensively, ecosystems often exhibit complicated intrinsic dynamics that are not as well understood. As a first step towards assessing the contribution of this intrinsic variability to the total variability in the ocean, we examine the temporal scales of intrinsic variability in a marine plankton model suitable for use in climate model projections. Our rationale is that a better understanding of the time scales over which intrinsic variability manifests could help in the attribution of observed variability. Our model includes multiple phytoplankton, dissolved inorganic nutrients, and zooplankton and supports two oscillatory mechanisms: "R-oscillations", corresponding to patterns of species succession and associated with changes in resources, and "Z-oscillations", corresponding to changes in total phytoplankton biomass due to predator-prey interactions. Over a wide range of model parameters, we found that while Z-oscillations typically occurred on time scales not exceeding 60 days, R-oscillations ranged from roughly 100 to 900 days under predation-free conditions, and R-oscillations occurred on longer time scales when interacting with Z-oscillations. Thus the two kinds of oscillations can be easily distinguished. At high grazing rates, we identified aperiodic cases where the dominant period never resolved, with distinct regimes emerging over decadal (or longer) time scales. These chaotic regime shifts are likely highly dependent on the model parameters and structure. More work must be done to understand how these oscillations interact with physical forcings
Evaluation of vitamin D bioaccessibility and mineral solubility from test meals containing meat and/or cereals and/or pulses using in vitro digestion
No full textIn this study, we evaluated vitamin D and mineral (iron, zinc, magnesium) transfer to the bolus aqueous phase during the digestion of meals with/without pulses. We performed in vitro digestions using test meals made either of i) beef and/or semolina and/or chickpeas, or of ii) potatoes supplemented or not with fibers, phytates, tannins and saponins. Chickpea presence led to a decrease in vitamin D bioaccessibility (-56%, p < 0.05) and mineral solubility (-28% for iron, p < 0.05) compared with meals with beef and/or semolina only. This effect was largely compensated for vitamin D by the fact that this vitamin was more stable during digestion of meals based on plant foods only than of meals with beef. Tannins were the most deleterious compounds for iron solubility, while phytates and tannins decreased vitamin D bioaccessibility. Agronomical or technical solutions to selectively decrease the amount in pulses of compounds that affect micronutrient bioavailability should be further explored
Cats Felis catus as a threat to bats worldwide : a review of the evidence
No full textCats Felis catus, in all their forms (domestic, free-roaming/stray and feral), have been identified as a major global threat to biodiversity, especially birds and small mammals. However, there has been little previous consideration of the extent and impact of predation of bats by cats, or of whether specific characteristics make certain species of bats particularly vulnerable to predation by cats. We reviewed the impact of cats on bats, based on a collation of scientific literature and the International Union for Conservation of Nature (IUCN) Red List database. Our aim was to produce a synthesis of the extent to which cats prey upon and threaten bats. We also collated available data on cat diet, which provide information on predation rates of bats by cats. Few studies (n = 44) have identified bat species preyed upon or threatened by cats, with a disproportionate number of studies from islands. In these studies, 86 bat species (about 7% of the global extant tally) are reported as preyed upon or threatened by cats, and about one quarter of these species are listed as Near Threatened or threatened (IUCN categories Critically Endangered, Endangered, or Vulnerable). In IUCN Red List assessments, cats are more frequently mentioned as a threat to threatened or Near Threatened bat species than to non-threatened species (IUCN category Least Concern). In studies reporting on the incidence of bats in cat dietary samples (scats, stomachs and guts), the frequency of occurrence of bats in samples averaged 0.7 +/- 2.1% (mean +/- standard deviation; n = 102). Many studies had sample sizes that were too small to be likely to detect bats. All forms of cat are reported to kill bats, and such predation has been reported in all major terrestrial habitats. We conclude that predation by cats is an under-appreciated threat to the world's bat species
Effect of pregnancy and concomitant antiretrovirals on the pharmacokinetics of tenofovir in women with HIV receiving tenofovir disoproxil fumarate-based antiretroviral therapy versus women with HBV receiving tenofovir disoproxil fumarate monotherapy
No full textTenofovir disoproxil fumarate (TDF) is recommended as part of antiretroviral therapy (ART) for pregnant women with HIV and as monotherapy for pregnant women with hepatitis B virus (HBV) monoinfection at high risk of transmitting infection to their infants. Tenofovir (TFV) plasma exposures are reduced during pregnancy; however, concomitant antiretrovirals and the viral infection itself can also influence TFV pharmacokinetics. Our aim was to compare TFV pharmacokinetics in pregnant women receiving TDF-based ART, with or without a ritonavir-boosted protease inhibitor (r/PI), to pregnant women with HBV receiving TDF monotherapy. Non-r/PI regimens were primarily integrase strand transfer inhibitors or nonnucleoside reverse transcriptase inhibitor-based regimens. Data were combined from a pharmacokinetic study of pregnant women with HIV on ART (PANNA), and a study assessing TFV pharmacokinetics in pregnant women with HBV (iTAP). A total of 196 pregnant women, 59 with HIV (32 receiving r/PIs) and 137 with HBV monoinfection were included. Intraindividual TFV area under the plasma concentration-time curve from time 0 to 24 hours was 25%, 26%, and 21% lower during the third trimester compared to I month postpartum in women with HIV using TDF and an r/PI or TDF and non-r/PI and women with HBV receiving TDF monotherapy, respectively. TFV area under the plasma concentration-time curve from time 0 to 24 hours was similar in pregnant women receiving non-r/PI to pregnant women with HBV receiving TDF monotherapy (1.84 vs 1.86 mu g . h/mL); however, pregnant women receiving TDF with an r/PI had higher exposures (2.41 mu g . h/mL; P < .01). Pregnancy reduces TFV exposure and the relative size was not impacted by concomitant antiretroviral drugs or viral infection, but a drug-drug interaction between TDF and r/PI remains during pregnancy, leading to higher exposures than those on TDF and non-r/PI or TDF monotherapy
On the influence of the current feedback to the atmosphere on the Western Mediterranean sea dynamics
No full textThe ocean Current FeedBack to the atmosphere (CFB) has been shown to be an unambiguous physical process to achieve proper equilibrium in the Ocean. However, its effects on the Western Mediterranean Sea (WMS) are not known. In this study, eddy-rich coupled ocean-atmosphere simulations are carried out for the WMS to assess the extent to which CFB alters the WMS circulation and to characterize the low-level wind and surface stress responses to CFB. By generating conduits of energy from oceanic currents to the atmosphere, CFB slows the mean circulation by about 10% and acts as an oceanic eddy killer, reducing the mesoscale activity by 25% and attenuating the intensity of their intermittency. It also alters the mean barotropic vorticity balance of the WMS Gyre, reducing the role of wind stress curl, nonlinear torque, and bottom pressure torque. By reducing the eddy-mean flow interaction, CFB has a large influence on the properties of the Algerian Current, reducing the presence of standing eddies near Sardinia and improving the realism of the circulation. It also modifies the Alboran Gyres formation and the Northern Current retroflection. Finally, coupling coefficients from the coupled simulations are estimated and are consistent with those for other regions. The CFB coupling coefficients can be used to parameterize the CFB in a forced ocean model. Overall, our results show that, as for other regions, the CFB is another physical mechanism to be considered for the representation of the WMS circulation
Mg/Ca, Sr/Ca and stable isotopes from the planktonic foraminifera T. sacculifer : testing a multi-proxy approach for inferring paleotemperature and paleosalinity
No full textOver the last decades, sea surface temperature (SST) reconstructions based on the Mg/Ca of foraminiferal calcite have frequently been used in combination with the delta O-18 signal from the same material to provide estimates of the delta O-18 of water delta O-18, a proxy for global ice volume and sea surface salinity (SSS). However, because of error propagation from one step to the next, better calibrations are required to increase the accuracy and robustness of existing isotope and element to temperature proxy relationships. Towards that goal, we determined Mg/Ca, Sr/Ca and the oxygen isotopic composition of Trilobatus sacculifer (previously referenced as Globigerinoides sacculifer) collected from surface waters (0-10 m) along a north-south transect in the eastern basin of the tropical and subtropical Atlantic Ocean. We established a new paleotemperature calibration based on Mg/Ca and on the combination of Mg/Ca and Sr/Ca. Subsequently, a sensitivity analysis was performed in which one, two or three different equations were considered. Results indicate that foraminiferal Mg/Ca allows for an accurate reconstruction of surface water temperature. Combining equations, delta O-18 can be reconstructed with a precision of about +/- 0.5 parts per thousand. However, the best possible salinity reconstruction based on locally calibrated equations only allowed for a reconstruction with an uncertainty of +/- 2.49. This was confirmed by a Monte Carlo simulation, applied to test successive reconstructions in an "ideal case" in which explanatory variables are known. This simulation shows that from a purely statistical point of view, successive reconstructions involving Mg/Ca and delta O-18 preclude salinity reconstructions with a precision better than +/- 1.69 and hardly better than +/- 2.65 due to error propagation. Nevertheless, a direct linear fit to reconstruct salinity based on the same measured variables (Mg/Ca and delta O-18(c)) was established. This direct reconstruction of salinity led to a much better estimation of salinity (+/- 0.26) than the successive reconstructions