Genomic and transcriptomic alterations in Leishmania donovani lines experimentally resistant to antileishmanial drugs

Leishmaniasis is a serious medical issue in many countries around the World, but it remains largely neglected in terms of research investment for developing new control and treatment measures. No vaccines exist for human use, and the chemotherapeutic agents currently used are scanty. Furthermore, for some drugs, resistance and treatment failure are increasing to alarming levels. The aim of this work was to identify genomic and trancriptomic alterations associated with experimental resistance against the common drugs used against VL: trivalent antimony (SbIII, S line), amphotericin B (AmB, A line), miltefosine (MIL, M line) and paromomycin (PMM, P line). A total of 1006 differentially expressed transcripts were identified in the S line, 379 in the A line, 146 in the M line, and 129 in the P line. Also, changes in ploidy of chromosomes and amplification/deletion of particular regions were observed in the resistant lines regarding the parental one. A series of genes were identified as possible drivers of the resistance phenotype and were validated in both promastigotes and amastigotes from Leishmania donovani, Leishmania infantum and Leishmania major species. Remarkably, a deletion of the gene LinJ.36.2510 (coding for 24-sterol methyltransferase, SMT) was found to be associated with AmB-resistance in the A line. In the P line, a dramatic overexpression of the transcripts LinJ.27.T1940 and LinJ.27.T1950 that results from a massive amplification of the collinear genes was suggested as one of the mechanisms of PMM resistance. This conclusion was reinforced after transfection experiments in which significant PMM-resistance was generated in WT parasites over-expressing either gene LinJ.27.1940 (coding for a D-lactate dehydrogenase-like protein, D-LDH) or gene LinJ.27.1950 (coding for an aminotransferase of branched-chain amino acids, BCAT). This work allowed to identify new drivers, like SMT, the deletion of which being associated with resistance to AmB, and the tandem D-LDH-BCAT, the amplification of which being related to PMM resistance.This work was supported by grants (to B.A. and J.M.R.) from Proyecto del Ministerio de Economía, Industria y Competitividad (SAF2013-47556-R and SAF2017-86965-R, co-financed with FEDER funds), and from ISCIII, proyecto " RD16/0027/0008″ Red de Enfermedades Tropicales, Subprograma RETICS del Plan Estatal de I + D + I 2013–2016 y cofinanciado FEDER: Una manera de hacer Europa. The CBMSO receives institutional grants from the Fundación Ramón Areces and from the Fundación Banco Santander. Also, this work was supported by the Spanish Grant Proyecto de Excelencia, Junta de Andalucía, Ref. CTS-7282 (to F.G.

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Les acides nucléiques des feuilles et des chloroplastes au cours de l'induction photopériodique de la floraison chez l'épinard (Spinacia oleracera L.)

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Les acides nucléiques des feuilles et des chloroplastes au cours de l'induction photopériodique de la floraison chez l'épinard (Spinacia oleracera L.)

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

The Reduction of Protochlorophyllide into Chlorophyllide. III The phototransformability of the forms of the protochlorophyllide-lipoprotein complex found in Darkness

peer reviewedThree distinct forms of the protochlorophyllide lipoprotein complex are found in darkness within the etiolated leaf: a native form absorbing at 647-648 nm, a transformed, still active 639-640 nm form, and a transformed, denatured 627-628 nm form. Methods for producing the tranformed forms are freezing and thawing, extraction, heat and acid treatments. The significance of these forms is discussed in realtion to the phototransformability of the complex: it is suggested that pigment-pigment interaction is not required for phototransformation while a given binding to the protein is required

Sur les cytochromes des chloroplastes : variations de leur teneur en rapport avec l'âge foliaire et le contenu en chlorophylle

Le contenu en cytochromes totaux s'abaisse dans les chloroplastes au fur et à mesure de leur vieillissement. On en trouve environ 3 fois moins dans les chloroplastes des feuilles âgées ou vieillissantes que dans les chloroplastes des feuilles jeunes à demi étalées. Dans les feuilles âgées, on peut démontrer un rapport constant entre le contenu en cytochromes chloroplastiques totaux et le contenu en chlorophylle totale. Dans ces feuilles, il y a entre 200 à 300 molécules de chlorophylle pour 1 molécule de cytochrome f ou b6 ; le rapport b6/f est voisin de l'unité ; la quantité calculée de cytochrome b3 est de loin plus faible que celle des deux cytochromes majeurs des chloroplastes (f + b6) pris ensemble. Les auteurs discutent une hpothèse sur la constitution d l'unité photosynthétique intralamellaire.The content in total cytochromes decreases in the chloroplasts during their ageing. There is three times less cytochromes in the chloroplasts of old leaves than in the chloroplasts of half-expanded leaves. In the old leaves the ratio between the content in total cytochromes and the content in total chorophyll is nearly constant. In these leaves, there are about 200 to 300 molecules of chlorophyll per 1 molecule of cytochrome f or b6 ; the ratio b6/f is near unity ; the calculated quantity of cyochrome b3 is much more lower than the quantity of the two major chloroplast cytochromes (f + b6). The authors discuss a possible hypothesis on the composition of the intralamellar photosynthetic unit

Transitory pigment-protein complexes similar to photosynthesis active centres during protochlorophyll(ide) photoreduction

peer reviewedBy illuminating etiolated bean leaves (Phaseolus vulgaris, var. Commodore) at temperatures around 178 K, and by freezing them in liquid nitrogen, hitherto unknown intermediates in the reduction of protochlorophyll(ide) to chlorophyll(ide) have been trapped. These intermediates appear to have red absorption bands located at wavelengths longer than 680 nm, up to 750 nm. They consist of pigment-protein complexes with a very short life time at room temperature. They do not emit any appreciable fluorescence at 77 K. When heated to temperatures above 178 K, they are transformed in the dark into a chlorophyll(ide)-protein complex: the P688-678 form already described. Energy is transferred from short wavelength absorbing pigments to the intermediate long wavelength pigments. The significance of the intermediates described, especially their similarity to photosynthetic reaction centres, are discussed briefly. © 1977

Ultrastructure and Fluorescence Emission Spectra of the Chloroplasts of Acetabularia and Batophora²

peer reviewe