Dynamique de la conductance hydraulique chez l'olivier de table (Olea europaea L., cv Meski)

Hydraulic Conductance Dynamic in Olive Table Tree (Olea europaea L. cv Meski). Cette étude expose les effets de l'aménagement des pâturages par la digue filtrante sur la dynamique de la végétation. Dans les régions sahéliennes, de nombreuses techniques sont appliquées sur les sols pour la restauration des parcours dégradés. La digue filtrante s'intéresse particulièrement aux axes de drainage ou bas-fonds en dégradation. La méthode d'étude a consisté à évaluer l'impact des digues filtrantes par l'inventaire de la végétation, la mesure de la biomasse produite, et l'analyse chimique d'échantillons de fourrage et de sol. Ces observations ont été faites à la fois sur l'espace aménagé et sur un espace témoin représentatif en deux fois durant cinq ans. Les observations sur l'espace aménagé (stations d'observation d'un ha) ont été faites en fonction du gradient par rapport à la digue filtrante tandis que sur le témoin (station d'observation d'un ha), les mesures ont été homogénéisées sur l'ensemble de la parcelle. Les résultats obtenus des inventaires de végétation montrent un effet positif de l'aménagement sur la dynamique de la végétation qui se maintient après cinq années. Les effets concernent la composition floristique pour laquelle certaines espèces connaissent une amélioration. Il s'agit de Panicum laetum (+ 5,9% en 1999 et + 1,9% en 2003), Setaria pallide fusca (+ 2,4 à + 8,6%), Cassia obtusifolia (+ 13,6% à + 9,3%) et Zornia glochidiata (- 2,9% à + 1,7 %). Les espèces en régression sont surtout composées de Schoenefeldia gracilis (+ 1,7% à - 12%) et Microchloa indica (- 28,9% à - 12,1% entre 1999 et 2003). L'écart de recouvrement du sol entre la parcelle aménagée et le témoin a été de -0,4% en 1999 contre + 14,6% en 2003. La biomasse produite et la capacité de charge ont connu une expansion allant de 3,14 à 4,5 fois par rapport à l'espace non aménagé. Cependant, des suivis doivent encore être maintenus en associant surtout les effets de l'exploitation (fauche et pâture) pour mieux préciser l'efficacité et la durabilité de ces aménagements sur les zones pastorales en même temps que des stratégies sont définies au niveau village sur la gestion de ces espaces restaurés

Mutations in DNAH1, which encodes an inner arm heavy chain dynein, lead to male infertility from multiple morphological abnormalities of the sperm flagella.

International audienceTen to fifteen percent of couples are confronted with infertility and a male factor is involved in approximately half the cases. A genetic etiology is likely in most cases yet only few genes have been formally correlated with male infertility. Homozygosity mapping was carried out on a cohort of 20 North African individuals, including 18 index cases, presenting with primary infertility resulting from impaired sperm motility caused by a mosaic of multiple morphological abnormalities of the flagella (MMAF) including absent, short, coiled, bent, and irregular flagella. Five unrelated subjects out of 18 (28%) carried a homozygous variant in DNAH1, which encodes an inner dynein heavy chain and is expressed in testis. RT-PCR, immunostaining, and electronic microscopy were carried out on samples from one of the subjects with a mutation located on a donor splice site. Neither the transcript nor the protein was observed in this individual, confirming the pathogenicity of this variant. A general axonemal disorganization including mislocalization of the microtubule doublets and loss of the inner dynein arms was observed. Although DNAH1 is also expressed in other ciliated cells, infertility was the only symptom of primary ciliary dyskinesia observed in affected subjects, suggesting that DNAH1 function in cilium is not as critical as in sperm flagellum

PTPA variants and impaired PP2A activity in early-onset parkinsonism with intellectual disability

The protein phosphatase 2A complex (PP2A), the major Ser/Thr phosphatase in the brain, is involved in a number of signalling pathways and functions, including the regulation of crucial proteins for neurodegeneration, such as alpha-synuclein, tau and LRRK2. Here, we report the identification of variants in the PTPA/PPP2R4 gene, encoding a major PP2A activator, in two families with early-onset parkinsonism and intellectual disability. We carried out clinical studies and genetic analyses, including genome-wide linkage analysis, whole-exome sequencing, and Sanger sequencing of candidate variants. We next performed functional studies on the disease-associated variants in cultured cells and knock-down of ptpa in Drosophila melanogaster. We first identified a homozygous PTPA variant, c.893T&gt;G (p.Met298Arg), in patients from a South African family with early-onset parkinsonism and intellectual disability. Screening of a large series of additional families yielded a second homozygous variant, c.512C&gt;A (p.Ala171Asp), in a Libyan family with a similar phenotype. Both variants co-segregate with disease in the respective families. The affected subjects display juvenile-onset parkinsonism and intellectual disability. The motor symptoms were responsive to treatment with levodopa and deep brain stimulation of the subthalamic nucleus. In overexpression studies, both the PTPA p.Ala171Asp and p.Met298Arg variants were associated with decreased PTPA RNA stability and decreased PTPA protein levels; the p.Ala171Asp variant additionally displayed decreased PTPA protein stability. Crucially, expression of both variants was associated with decreased PP2A complex levels and impaired PP2A phosphatase activation. PTPA orthologue knock-down in Drosophila neurons induced a significant impairment of locomotion in the climbing test. This defect was age-dependent and fully reversed by L-DOPA treatment. We conclude that bi-allelic missense PTPA variants associated with impaired activation of the PP2A phosphatase cause autosomal recessive early-onset parkinsonism with intellectual disability. Our findings might also provide new insights for understanding the role of the PP2A complex in the pathogenesis of more common forms of neurodegeneration.</p

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

WATER STRESS IN TANNAT AND DURAS GRAPEVINE CULTIVARS (VITIS VINIFERA L.): LEAF PHOTOSYNTHESIS AND GRAPE PHENOLIC MATURITY

Our study focuses on the physiological responses and berries phenolic maturity of Tannat and Duras red wine grape cultivars, which are autochthonous from the southern France, under water stress condition from pre-véraison to harvest by limiting water availability to 30% of the control well-watered. Methode and result : Predawn and midday leaf water potentials served as an indicator to maintain water stress level compared to the control. The seasonal reduction of leaf net assimilation rate under saturating irradiance (An) under water stress over six weeks stress period versus well-watered was 60% for Tannat and Duras as compared to 64 and 46% for leaf stomatal conductance (gs) for Tannat and Duras cultivars respectively. These responses qualify Tannat as a good candidate for adapting to limited water availability. For both Tannat and Duras cultivars, relationships between the fresh mass, skin and flesh in six different berry size categories, ranged from about 0.5 to 2.0 g, were assessed on ripe fruit from grapevines subjected to well-watered and water stressed treatments. Fresh mass components for both treatments varied significantly depending on the grape cultivar and water availability. Tannat showed that seed represented around 6%, skin around 12%, and flesh about 82% of the berry total fresh weight. The Duras cultivar showed that seed represented around 3%, skin around 12% and flesh around 85%. Exact proportion of seed, skin and flesh varied according to berry size category. There was an increase in total seed mass per berry to water stress treatment. Anthocyanin content and the seed tannin concentration varied depending on the grape variety and water stress treatment. In comparison with skin tannin or anthocyanin content, seed tannin varied more with berry size and less with vine water status. Tannat variety showed a positive effect of water stress on anthocyanin content but not Duras. At last, seed and skin tannin concentrations decreased with berry fresh weight

Effetto della disponibilita’ idrica sulla risposta eco-fisiologica e sulle caratteristiche dell’acino di quattro varieta’ autoctone della regione di “Midi-Pyrénées” in Francia.

In due successive stagioni vegetative è stato studiato l’effetto dello stress idrico su alcune caratteristiche eco-fisiologiche e morfologiche dell’acino di quattro varietà di vite: Côt (=Malbec), Négrette, Tannat e Duras; autoctone dell’area Sud-Ovest della Francia (Regione “Midi-Pyrénées”). All’inizio dell’invaiatura su metà delle piante di ciascuna varietà, secondo uno schema completamente randomizzato, è stato imposto uno stress idrico diminuendo del 70% i volumi irrigui utilizzati per il controllo. Dopo sei settimane, la diminuzione delle disponibilità idriche ha comportato un abbassamento, rispetto alle piante irrigate, della conduttanza stomatica e dell’assimilazione massima. La distribuzione del peso fresco dell’acino, misurata in 6 diverse categorie di dimensione degli acini, ha messo in evidenza un significativo aumento delle categorie di acino con peso inferiore ad 1.0 g nelle piante sottoposte a stress idrico rispetto a quelle ben irrigate. Gli acini sottoposti a stress idrico avevano inoltre un maggior peso relativo dei semi rispetto a buccia e polpa. La concentrazione in antociani e tannini della buccia non è stata significativamente modificata dal trattamento irriguo in Côt, Négrette mentre significativamente più elevata è stata in Tannat e Duras. La concentrazione di tannini dei semi è stata influenzata dal trattamento irriguo in relazione alla cultivar ed alla dimensione dell’acino. In definitiva la concentrazione dei tannini dei semi e della buccia decresce con l’aumentare del peso fresco dell’acino, mentre la concentrazione gli antociani della buccia è meno influenzata dalle dimensioni dell’acino e positivamente associata al deficit idrico

Association Study of CARD8 (p.C10X) and NLRP3 (p.Q705K) Variants with Rheumatoid Arthritis in French and Tunisian Populations

International audienceThe objective of the study was to investigate the association of caspase activating and recruitment domain 8 (CARD8) and nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 (NLRP3) polymorphisms with rheumatoid arthritis (RA) in Tunisian and French populations. CARD8 (c.30T\backslashtextgreaterA, rs2043211) and NLRP3 (c.2113C\backslashtextgreaterA, rs35829419) single nucleotide polymorphisms (SNPs) were genotyped in 100 French RA trio families and 141 Tunisian patients with RA and 191 unrelated healthy controls, using TaqMan(®) allelic discrimination assay. The genetic analyses for the association and linkage in French families were performed using the comparison of allelic frequencies (AFBAC), the genotype relative risk (GRR) and the transmission disequilibrium test (TDT). Data for case and control samples were analysed by chi-square-test, GRR and odds ratio (OR). No significant differences between alleles and genotypes frequencies were detected in French trio and Tunisian patients with RA and controls, either with CARD8 or with NLRP3 SNPs both in French and in Tunisian populations. Moreover, stratifying patients according to the presence of rheumatoid factor (RF), anti-cyclic peptides antibodies (ACPA), erosion, nodules, other autoimmune disease or HLA-DRB1*04-positive subgroups did not show any significant association with CARD8 or NLRP3 (P ≥ 0.05). This study suggests that variations in the innate immunity genes CARD8 (p.C10X) and NLRP3 (p.Q705K) have no effect on RA susceptibility either in the Tunisian or in the French population

Differential impact of consanguineous marriages on autosomal recessive diseases in Tunisia

International audienceObjectives Consanguinity is common in Tunisia. However, little information exists on its impact on recessive disorders. In this study, we evaluate the impact of consanguineous marriages on the occurrence of some specific autosomal recessive disorders and consider how other factors, such as population substructure and mutation frequency, may be of equal importance in disease prevalence. Methods Consanguinity profiles were retrospectively studied among 425 Tunisian patients suffering from autosomal recessive xeroderma pigmentosum, dystrophic epidermolysis bullosa, nonsyndromic retinitis pigmentosa, Gaucher disease, Fanconi anemia, glycogenosis type I, and ichthyosis, and compared to those of a healthy control sample. Results Consanguinity was observed in 341 cases (64.94%). Consanguinity rates per disease were 75.63, 63.64, 60.64, 61.29, 57.89, 73.33, and 51.28%, respectively. First-cousin marriages were the most common form of consanguinity (48.94%) with the percentages of 55.46, 45.46, 47.87, 48.39, 45.61, 56.66, and 35.90%, respectively. A very high level of geographic endogamy was also observed (93.92%), with the values by disease ranging between 75.86 and 96.64%. We observed an overall excess risk associated to consanguinity of nearly sevenfold which was proportional to the number of affected siblings and the frequency of disease allele in the family. Consanguinity was significantly associated with the first five cited diseases (odds ratio=24.41, 15.17, 7.5, 5.53, and 5.07, respectively). However, no meaningful effects were reported among the remaining diseases. Conclusions This study reveals a variation in the excess risk linked to consanguinity according to the type of disorder, suggesting the potential of cryptic population substructure to contribute to disease incidence in populations with complex social structure like Tunisia. It also emphasizes the role of other health and demographic aspects such as mutation frequency and reproductive replacement in diseases etiology. (c) 2015 Wiley Periodicals, Inc

Elevated CO2 has concurrent effects on leaf and grain metabolism but minimal effects on yield in wheat

While the general effect of CO2 enrichment on photosynthesis, stomatal conductance, nitrogen elemental content or yield has been documented, there is still some uncertainty as to whether there are interactive effects between CO2 enrichment and other factors (such as temperature, geographical location, water availability and cultivar). In addition, the metabolic coordination between leaves and grains, which is crucial for crop responsiveness to elevated CO2, has never been examined closely. Here, we addressed these two aspects by taking advantage of several FACE experiments across five different countries using multi-level analyses. There was little effect of elevated CO2 on yield (except in USA) likely due to photosynthetic capacity acclimation, as reflected by protein profiles. Also, there was a significant decrease in leaf amino acids (threonine) and macro-elements (such as K) at elevated CO2, while other elements such as magnesium (Mg) or sulfur (S) increased. Despite the insignificant effect of CO2-enrichment on yield, grains appeared to be significantly depleted (as expected) in N, but also in threonine, the S-containing amino acid methionine and Mg. Overall, our results suggest a strong detrimental effect of CO2 enrichment on nutrient availability and remobilization from leaves to grains