Un nouvel Indice Diatomique Pratique pour l'évaluation de la qualité des eaux en réseau de surveillance

L'Indice de Polluosensibilité Spécifique (IPS) est considéré comme l'un des indices diatomiques les plus performants pour l'évaluation de la qualité des cours d'eau. Son utilisation en réseau de surveillance reste cependant limitée en raison de la nécessité de travailler au niveau spécifique voire infraspécifique et de la systématique en perpétuelle évolution. A l'opposé, l'Indice Diatomique Générique (IDG) est plus accessible dans sa mise en oeuvre mais ne permet pas d'obtenir des résultats très fiables. Un nouvel Indice Diatomique Pratique (IDP) a donc été mis au point sur un bassin versant expérimental à partir d'un jeu de 86 relevés. Dans un premier temps, les inventaires ont été classés en fonction des écarts observés entre IPS et IDG. Dans un second temps, ont été identifiées les espèces responsables de ces écarts en prenant en compte celles présentant une abondance relative supérieure à 5 % et une différence de polluosensibilité avec le genre correspondant supérieure ou égale à 0,4. Plusieurs IDP ont été mis au point et leurs performances, par rapport à l'IPS, étudiées. Il apparaît que la prise en compte des espèces responsables des écarts supérieurs ou égaux à 2 constitue le meilleur compromis entre fiabilité et applicabilité en réseau. Cette méthodologie a été appliquée aux 480 relevés effectués dans le bassin Artois - Picardie et aux 550 espèces inventoriées. Elle permet de proposer un indice diatomique pratique basé sur l'identification de 45 genres et 91 espèces.Macroinvertebrates constitute the main biological support for an evaluation of the quality of water courses and are, therefore, widely put to use in monitoring networks. However, for major water courses and canalized waterways the use of other methodologies is imperative. Diatoms and diatom indices are well adapted to the study of these environments. Among these, the Specific Polluosensitivity Index (SPI) established by CEMAGREF seems to be one of the better performing diatom indices. Calculation of this index relies on the Zelinka & Marvan formula derived from the saprobic system: SPI=[Epsilon]A[inf]j v[inf]j i[inf]j / [Epsilon] A[inf]j v[inf]j where A[inf]j is the relative abundance of the species j, v j is its indicative value ( 1 [smaller or equal] v[inf]j [smaller or equal] 3) and i[inf]j its pollution sensitivity (1 [smaller or equal] i[inf]j [smaller or equal] 5). The values initially falling in the range between 1 and 5 are transformed into values comprised between 1 and 20, in order to make comparisons between the various existing indices easier. Five categories of water quality can be distinguished according to the value of the index: SPI [Bigger or equal] 16: zero pollution or low eutrophication; 13.5 [smaller or equal] SPI < 16: moderate eutrophication; 11 [smaller or equal] SPI < 13.5: moderate pollution or heavy eutrophication; 7 [smaller or equal] SPI < 11: high pollution; SPI < 7 : very heavy pollution. However, the SPI index is rarely used because of two main obstacles: it requires data at a specific or even infraspecific level, and it is based on constantly changing systematics. Progress towards increased accessibility and, therefore, larger application was made with the elaboration of the Generic Diatomic Index (IDG) based on the same principle as the SPI. However, this GDI does not yield reliable results, in so far as certain genera, such as Navicula and Nitzschia, contain species with a widely differing ecologies. In order to provide a methodology that can be used as a matter of routine, a protocol for the elaboration of a Practical Diatomic Index (PDI) was established and tested on 86 inventories from the water basin of the river Aa (North of France). These were first classified into four categories according to the variations observed between SPI and GDI: category 1: |SPI-GDI| [bigger or equal] 3 ; category 2: 2 [smaller or equal] |SPI-GDI|; category 3: 1 [smaller or equal] |SPI-DGI| < 2 ; category 4: |SPI-DGI| < 1. For each of the first three categories, the species responsible for the variations were identified, taking into consideration those with a relative abundance of more than 5%, the pollution sensitivity of which showed, compared to the corresponding genus, a variation higher than or equal to 0.4. Thus, three indices corresponding respectively to category 1 (PDI1), 2 (PDI2), and 3 (PDI3) were proposed and tested against the SPI taken as reference index. The results of this comparative study can be summarized as follows:- GDI=0.57 SPI + 5.47 r=0.801 (242 species), - PDI1=0.86 SPI + 1.12 r=0.972 ( 27 species), - PDI2=0.95 SPI + 0.55 r=0.991 ( 39 species), - PDI3=0.96 SPI + 0.45 r=0.994 ( 42 species). To test the implications of replacing the presently used SPI by this practical index, a comparative study of the classification of inventories in four categories of hydrobiological quality was also carried out. This study shows that the mean, at - 1.76 ± 2.25 for the GDI, is reduced to 0.14 ± 0.94 for PDI1, to - 0.07 ± 0.51 for PDI2, and to - 0.07 ± 0.45 for PDI3. Given the variability of the index at one and the same site and in one sampling, PDI2 considered to be the best compromise between reliability and network applicability. The methodology corresponding to PDI2 was applied to the 480 samplings carried out in the Artois-Picardie basin and a new Practical Diatom Index is thus proposed for the monitoring of the 200 sites making up the monitoring network of the Artois-Picardie water basin. This PDI, built on a base of more than 550 species and varieties, rests on the joint determination of 45 genera and 91 species of which the pollution sensitivity coefficients and the indicative values are given

Traduction et pré-test d’un outil de mesure multidimensionnel centré sur les besoins des familles d'enfants non-verbaux, en situation de handicap.

peer reviewed3. Good health and well-bein

FHR4-based immunoconjugates direct complement-dependent cytotoxicity and phagocytosis towards HER2-positive cancer cells

Directing selective complement activation towards tumour cells is an attractive strategy to promote their elimination. In the present work, we have generated heteromultimeric immunoconjugates that selectively activate the complement alternative pathway (AP) on tumour cells. We used the C4b-binding protein C-terminal-alpha-/beta-chain scaffold for multimerisation to generate heteromultimeric immunoconjugates displaying (a) a multivalent-positive regulator of the AP, the human factor H-related protein 4 (FHR4) with; (b) a multivalent targeting function directed against erbB2 (HER2); and (c) a monovalent enhanced GFP tracking function. Two distinct VHH targeting two different epitopes against HER2 and competing either with trastuzumab or with pertuzumab-recognising epitopes [VHH(T) or VHH(P)], respectively, were used as HER2 anchoring moieties. Optimised high-FHR4 valence heteromultimeric immunoconjugates [FHR4/VHH(T) or FHR4/VHH(P)] were selected by sequential cell cloning and a selective multistep His-Trap purification. Optimised FHR4-heteromultimeric immunoconjugates successfully overcame FH-mediated complement inhibition threshold, causing increased C3b deposition on SK-OV-3, BT474 and SK-BR3 tumour cells, and increased formation of lytic membrane attack complex densities and complement-dependent cytotoxicity (CDC). CDC varies according to the pattern expression and densities of membrane-anchored complement regulatory proteins on tumour cell surfaces. In addition, opsonised BT474 tumour cells were efficiently phagocytosed by macrophages through complement-dependent cell-mediated cytotoxicity. We showed that the degree of FHR4-multivalency within the multimeric immunoconjugates was the key element to efficiently compete and deregulate FH and FH-mediated convertase decay locally on tumour cell surface. FHR4 can thus represent a novel therapeutic molecule, when expressed as a multimeric entity and associated with an anchoring system, to locally shift the complement steady-state towards activation on tumour cell surface

CD32+CD4+memory T cells are enriched for total HIV-1 DNA in tissues from humanized mice

CD32 has raised conflicting results as a putative marker of the HIV-1 reservoir. We measured CD32 expression in tissues from viremic and virally suppressed humanized mice treated relatively early or late after HIV-1 infection with combined antiretroviral therapy. CD32 was expressed in a small fraction of the memory CD4(+) T-cell subsets from different tissues in viremic and aviremic mice, regardless of treatment initiation time. CD32(+) memory CD4(+) T cells were enriched in cell associated (CA) HIV-1 DNA but not in CA HIV-1 RNA as compared to the CD32(-) CD4(+) fraction. Using multidimensional reduction analysis, several memory CD4(+)CD32(+) T-cell clusters were identified expressing HLA-DR, TIGIT, or PD-1. Importantly, although tissue-resident CD32(+)CD4(+) memory cells were enriched with translation-competent reservoirs, most of it was detected in memory CD32-CD4(+) T cells. Our findings support that CD32 labels highly activated/exhausted memory CD4(+) T-cell subsets that contain only a small proportion of the translation-competent reservoir

Predominance of the heterozygous CCR5 delta‐24 deletion in African individuals resistant to HIV infection might be related to a defect in CCR5 addressing at the cell surface

Introduction The chemokine receptor CCR5 is the main co-receptor for R5-tropic HIV-1 variants. We have previously described a novel 24-base pair deletion in the coding region of CCR5 among individuals from Rwanda. Here, we investigated the prevalence of hCCR5 Delta 24 in different cohorts and its impact on CCR5 expression and HIV-1 infection in vitro. Methods We screened hCCR5 Delta 24 in a total of 3232 individuals which were either HIV-1 uninfected, high-risk HIV-1 seronegative and seropositive partners from serodiscordant couples, Long-Term Survivors, or HIV-1 infected volunteers from Africa (Rwanda, Kenya, Guinea-Conakry) and Luxembourg, using a real-time PCR assay. The role of the 24-base pair deletion on CCR5 expression and HIV infection was assessed in cell lines and PBMC using mRNA quantification, confocal analysis, flow and imaging cytometry. Results and Discussion Among the 1661 patients from Rwanda, 12 individuals were heterozygous for hCCR5 Delta 24 but none were homozygous. Although heterozygosity for this allele may not confer complete resistance to HIV-1 infection, the prevalence of the mutation was 2.41% (95%CI: 0.43; 8.37) in 83 Long-Term Survivors (LTS) and 0.99% (95%CI: 0.45; 2.14) in 613 HIV-1 exposed seronegative members as compared with 0.35% (95% Cl: 0.06; 1.25) in 579 HIV-1 seropositive members. The prevalence of hCCR5 Delta 24 was 0.55% (95%CI: 0.15; 1.69) in 547 infants from Kenya but the mutation was not detected in 224 infants from Guinea-Conakry nor in 800 Caucasian individuals from Luxembourg. Expression of hCCR5 Delta 24 in cell lines and PBMC showed that the hCCR5 Delta 24 protein is stably expressed but is not transported to the plasma membrane due to a conformational change. Instead, the mutant receptor was retained intracellularly, colocalized with an endoplasmic reticulum marker and did not mediate HIV-1 infection. Co-transfection of hCCR5 Delta 24 and wtCCR5 did not indicate a transdominant negative effect of CCR5 Delta 24 on wtCCR5. Conclusions Our findings indicate that hCCR5 Delta 24 is not expressed at the cell surface. This could explain the higher prevalence of the heterozygous hCCR5 Delta 24 in LTS and HIV-1 exposed seronegative members from serodiscordant couples. Our data suggest an East-African localization of this deletion, which needs to be confirmed in larger cohorts from African and non-African countries

Flocculation onset in Saccharomyces cerevisiae: effect of ethanol, heat and osmotic stress

Aims: To examine the effect of different stress conditions on the onset of flocculation in an ale-brewing strain, Saccharomyces cerevisiae NCYC 1195. Methods and Results: Flocculation was evaluated using the method of Soares, E.V. and Vroman, A. [Journal of Applied Microbiology (2003) 95, 325]; plasma membrane integrity was accessed using propidium iodide and the staining of the yeast cell wall was performed using calcofluor white M2R. Cells in exponential phase of growth were subjected to different stress conditions. The addition of 1%, 3% and 5% (v/v) ethanol, 1% and 3% (v/v) isopropanol or a brief heat shock (52ºC, 5 min), did not induce an early flocculation phenotype when compared with control cells. The addition of 10% (v/v) ethanol, a continuous mild heat-stress (37ºC) or an osmotic stress (0.5 or 1 mol l-1 of NaCl) did not induce a flocculent phenotype. Conclusions: Flocculation seems not to be induced as a response to different chemical (ethanol and isopropanol) and physical (heat and osmotic) stress conditions. Conversely, osmotic and ethanol [10% (v/v)] stress, as well as a continuous mild heat shock (37ºC), have a negative impact on the phenotype expression of flocculation. Significance and Impact of the Study: The findings reported here contribute to the elucidation of the control of yeast flocculation. This information might be useful to the brewing industry, as the time when the onset of flocculation occurs can determine the fermentation performance and the beer quality, as well as in other biotechnological industries where flocculation can be used as a cell separation process.ERASMUS; ISEP (Portugal)

Cytotoxic CD8+ T Cells Expressing CXCR5 Are Detectable in HIV-1 Elite Controllers After Prolonged In Vitro Peptide Stimulation

Antiretroviral therapy (ART) is not curative as HIV-1 persists in long-lived viral reservoirs. Consequently, patients are dependent on life-long drug adherence with possible side effects. To overcome these limitations strategies of a functional cure aim at ART free viral remission. In this study, we sought to identify detailed subsets of anti-viral CD8+ T cell immunity linked to natural long-term control of HIV-1 infection. Here, we analyzed HIV controllers and ART suppressed progressors for in vitro viral suppressive capacity (VSC) at baseline and after peptide stimulation. Functional properties and phenotypes of CD8+ T cells were assessed by IFN-γ ELISPOT and 18 color flow cytometry. HIV controllers showed significantly increased suppression at baseline as well as after peptide stimulation. IFN-γ secretion and the proliferation marker Ki67 positively correlated with VSC. Moreover, the detailed phenotype of three distinct multifunctional memory CD8+ T cell subsets were specific traits of HIV controllers of which two correlated convincingly with VSC. Our results underline the importance of multifunctional CD8+ T cell responses during natural control. Especially the role of CXCR5 expressing cytotoxic subsets emphasizes potential surveillance in sites of reservoir persistence and demand further study.</jats:p

Phocid Seal Leptin: Tertiary Structure and Hydrophobic Receptor Binding Site Preservation during Distinct Leptin Gene Evolution

The cytokine hormone leptin is a key signalling molecule in many pathways that control physiological functions. Although leptin demonstrates structural conservation in mammals, there is evidence of positive selection in primates, lagomorphs and chiropterans. We previously reported that the leptin genes of the grey and harbour seals (phocids) have significantly diverged from other mammals. Therefore we further investigated the diversification of leptin in phocids, other marine mammals and terrestrial taxa by sequencing the leptin genes of representative species. Phylogenetic reconstruction revealed that leptin diversification was pronounced within the phocid seals with a high dN/dS ratio of 2.8, indicating positive selection. We found significant evidence of positive selection along the branch leading to the phocids, within the phocid clade, but not over the dataset as a whole. Structural predictions indicate that the individual residues under selection are away from the leptin receptor (LEPR) binding site. Predictions of the surface electrostatic potential indicate that phocid seal leptin is notably different to other mammalian leptins, including the otariids. Cloning the grey seal leptin binding domain of LEPR confirmed that this was structurally conserved. These data, viewed in toto, support a hypothesis that phocid leptin divergence is unlikely to have arisen by random mutation. Based upon these phylogenetic and structural assessments, and considering the comparative physiology and varying life histories among species, we postulate that the unique phocid diving behaviour has produced this selection pressure. The Phocidae includes some of the deepest diving species, yet have the least modified lung structure to cope with pressure and volume changes experienced at depth. Therefore, greater surfactant production is required to facilitate rapid lung re-inflation upon surfacing, while maintaining patent airways. We suggest that this additional surfactant requirement is met by the leptin pulmonary surfactant production pathway which normally appears only to function in the mammalian foetus

Functional Consequences of the Human Leptin Receptor ( LEPR ) Q223R Transversion

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93715/1/oby.2008.489.pd