Effet de l'azote et du rayonnement sur le développement des feuilles et de l'épi chez le blé d'hiver : mise en place de l'appareil foliaire et de la structure de l'épi

Des plantes monotalles élevées depuis le semis en faible nutrition azotée ou en faible rayonnement ont été transférées en conditions optimales à différents stades du développement. La carence en N et l'ombrage ont augmenté le thermochrone et leur suppression l'a diminué. L'ombrage a diminué le nombre de feuilles (-2) et la carence en N le nombre final d'épillets (-4). Le nombre de grains par épi a varié de 54 à 111. L'azote a agi surtout sur la zone basale de l'épi et la lumière sur la moitié supérieure. La suppression de la carence en N a amélioré la fertilité d'abord à la base de l'épi et ensuite dans la zone médiane et distale. La suppression de l'ombrage a augmenté la fertilité uniformément sur tous les épillets. Après le stade «double ride», la perte de fertilité due à la carence azotée a été proportionnelle à la durée de la carence et n'a pas mis en évidence un stade de développement particulièrement sensible. En revanche, la période allant de la sortie de la dernière feuille à la floraison a présenté une sensibilité supérieure à un complément de lumière. L'existence d'un seuil limite de développement d'une fleur conditionnant sa fertilité est discutée.Leaf development and ear structure in wheat as affected by nitrogen and shading. Single main-stems of wheat grown in individual pots and in reduced light intensity (50%) or without N fertilizer were transferred to optimal conditions (light and nitrogen) at different stages. The effects on thermal time of appearance of successive leaves (thermochron, QT), on number of leaves and spikelets per ear and on grain number, ear structure and fertility of grain sites were analysed. Nitrogen deficiency (Nd) and shading decreased the rate of leaf appearance (figs 3, 4) and their suppression at terminal spikelet stage raised it (table I). Ligule appearance was more linearly related to thermal time than lamina appearance, and so was better for the calculation of thermochron value, possibly due to variation in laminal area (fig 10). The total number of primordia (leaves + spikelets) was decreased by both shading (-2) and Nd (-4). Shading decreased the number of leaves (-2) and Nd the number of spikelets (-4) (table II). The number of grains per ear ranged from 51 under fully stressed conditions to 111 under optimal conditions. Continuous Nd acted principally on fertility at the basal part of the ear and shading on the upper part (fig 5). The suppression of Nd increased the fertility successively in basal, median and upper parts of the ear (fig 6) and the suppression of shading increased the fertility uniformly in all spikelets (fig 7). No stage after double-ridge was significantly more sensitive to nitrogen changes than any other, there being a progressive reduction in grain number with thermal time. In contrast, the period between the appearance of the last leaf and anthesis was more sensitive to light change (fig 8). The number of sterile florets was similar in all spikelets (2-3) (fig 10) and the hypothesis of a minimum stage of floral development for grain siting has been discussed

Activation of liver X receptor decreases atherosclerosis in Ldlr⁻/⁻ mice in the absence of ATP-binding cassette transporters A1 and G1 in myeloid cells

Liver X receptor (LXR) activators decrease atherosclerosis in mice. LXR activators (1) directly upregulate genes involved in reverse cholesterol transport and (2) exert anti-inflammatory effects mediated by transrepression of nuclear factor-κB target genes. We investigated whether myeloid cell deficiency of ATP-binding cassette transporters A1 and G1 (ABCA1/G1), principal targets of LXR that promote macrophage cholesterol efflux and initiate reverse cholesterol transport, would abolish the beneficial effects of LXR activation on atherosclerosis. LXR activator T0901317 substantially reduced inflammatory gene expression in macrophages lacking ABCA1/G1. Ldlr(-/-) mice were transplanted with Abca1(-/-)Abcg1(-/-) or wild-type bone marrow (BM) and fed a Western-type diet for 6 weeks with or without T0901317 supplementation. Abca1/g1 BM deficiency increased atherosclerotic lesion complexity and inflammatory cell infiltration into the adventitia and myocardium. T0901317 markedly decreased lesion area, complexity, and inflammatory cell infiltration in the Abca1(-/-)Abcg1(-/-) BM-transplanted mice. To investigate whether this was because of macrophage Abca1/g1 deficiency, Ldlr(-/-) mice were transplanted with LysmCreAbca1(fl/fl)Abcg1(fl/fl) or Abca1(fl/fl)Abcg1(fl/fl) BM and fed Western-type diet with or without the more specific LXR agonist GW3965 for 12 weeks. GW3965 decreased lesion size in both groups, and the decrease was more prominent in the LysmCreAbca1(fl/fl)Abcg1(fl/fl) group. The results suggest that anti-inflammatory effects of LXR activators are of key importance to their antiatherosclerotic effects in vivo independent of cholesterol efflux pathways mediated by macrophage ABCA1/G1. This has implications for the development of LXR activators that lack adverse effects on lipogenic genes while maintaining the ability to transrepress inflammatory gene

CH92/082 and TME 6 cassava clones officially released for farmer growing in Malawi

Cassava clones CH92/082, TME 6 and BA95/070 were evaluated against Mbundumali, Phoso, Mulola and Sauti as checks. These clones were evaluated at Makoka, Mkondezi, Baka and Kasinthula Research Stations that represented different agro ecologies and in Mzuzu ADD under farmers' conditions. The objective of cassava improvement programme in Malawi is to develop cassava varieties that are: high yielding per unit area of land; tolerant to major diseases (cassava mosaic disease and cassava brown streak disease) and pests (cassava green mite and cassava mealy bug), adaptable to local environmental conditions and acceptable by end-users

A review of Cameroonian medicinal plants with potentials for the management of the COVID-19 pandemic

Since the outbreak in December 2019, in Wuhan (China) of COVID-19, approved drugs are still lacking and the world is seeking effective treatment. The purpose of this article is to review the medicinal plants with potential to be used as complementary therapies against COVID-19. Bibliographic information was searched in several databases (Google Scholar, PubMed, Scopus, ScienceDirect, PROTA, ResearchGate and GLOBEinMED), to retrieve relevant papers on (1) plants used to manage common symptoms of COVID-19, (2) plant secondary metabolites with confirmed inhibitory effects on COVID-19 and (3) plants exhibiting pharmacological activities of relevance for COVID-19 management. A total of 230 species was recorded as potential source of ingredients for the fight against the 2019 novel corona virus. Of these species, 30 contain confirmed antiCOVID-19 secondary metabolites, 90 are used traditionally to manage at least 3 common symptoms of COVID-19, 10 have immunostimulant activity, 52 have anti-inflamatory activity, 14 have antiviral properties and 78 species are documented as used to treat malaria. A PCA analysis showing cluster formatting among the recorded species indicates 4 groups of species and an array of possibility of using individual species or a combination of species for their complementary effects. The authors argue that Cameroonian medicinal plants can be of potential contribution to the fight against COVID-19. Further applied research is needed to provide more scientific evidence for their efficacy, to establish standard formulations and clinical studies as part of efforts to develop therapies for COVID-19