Traitements sylvicoles alternatifs en forêt boréale irrégulière sur la Côte-Nord : la réponse des communautés de coléoptères

Cette étude vise à déterminer l'impact de quatre traitements sylvicoles (CPRS, CPPTM et 2 types de coupes de jardinage) sur la diversité et l'abondance des coléoptères en forêt boréale irrégulière. Un dispositif d'échantillonnage a été déployé dans 4 blocs expérimentaux du 5 juin au 22 août 2007 et a permis de capturer 26 906 coléoptères regroupant 407 taxons de coléoptères répartis au sein de 52 familles distinctes. Les résultats montrent que la CPRS et la CPPTM modifient davantage la structure et la composition des communautés de coléoptères retrouvées dans l'aire d'étude que les coupes de jardinage. L'ouverture du milieu de même que les débris ligneux au sol et sur pied semblent des facteurs déterminants dans l'établissement de plusieurs espèces saproxyliques et non-saproxyliques. Les coupes de jardinage permettent le maintien des communautés étudiées; ces traitements sylvicoles s'inscrivent bien dans une perspective d'aménagement écosystémique et durable de la forêt boréale irrégulière

The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015

Interceptions and captures of Halyomorpha halys (Hemiptera: Pentatomidae) in Quebec from 2008 to 2018

The brown marmorated stink bug, Halyomorpha halys (Heteroptera: Pentatomidae), was monitored in southern Quebec through a network of 137 baited pyramid traps deployed in urban and rural habitats between 2014 and 2017. Overall, 73 adults and 9 nymphs were captured. The first capture in rural (an apple orchard) and in urban areas (in Montreal) were observed in 2016. In that same year, 87% of the 54 individuals (adults) caught in Montreal were from a single trap. Similarly in 2017, only two adults were captured in rural habitats and 87% of the 25 captures (16 adults and 9 nymphs) in urban habitats were from the same trap as in 2016. This trap was the only one in which nymphs of various stages were collected, which suggests population establishment in Montreal. Haplotyped specimens from this site (four adults and two nymphs) were all of the H1 haplotype. Over 40 interceptions and sightings by citizens during the period 2008-2018 are also reported.La punaise marbrée, Halyomorpha halys (Heteroptera: Pentatomidae), a été dépistée dans le sud du Québec à travers un réseau de 137 pièges pyramidaux appâtés déployés en milieux urbains et ruraux entre 2014 et 2017. Au total, 73 adultes et 9 nymphes ont été capturés. La première capture en milieu rural (un verger de pommiers) et les premières captures en milieu urbain (à Montréal) ont été rapportées en 2016. La même année, 87 % des 54 individus (adultes) capturés à Montréal provenaient du même piège. Similairement en 2017, seulement deux adultes ont été capturés en milieu rural et 87 % des 25 captures (16 adultes et 9 larves) en milieu urbain ont été observées dans le même piège qu’en 2016. Ce piège a aussi été le seul dans lequel des larves de différents stades ont été capturées, suggérant un établissement de population à Montréal. Les spécimens de ce site (quatre adultes et deux larves), séquencés à cette fin, se sont révélés être de l’haplotype H1. Plus de 40 observations et interceptions par les citoyens entre 2008 et 2018 sont aussi rapportées

Gene amplification and point mutations in pyrimidine metabolic genes in 5-fluorouracil resistant Leishmania infantum.

The human protozoan parasites Leishmania are prototrophic for pyrimidines with the ability of both de novo biosynthesis and uptake of pyrimidines.Five independent L. infantum mutants were selected for resistance to the pyrimidine analogue 5-fluorouracil (5-FU) in the hope to better understand the metabolism of pyrimidine in Leishmania. Analysis of the 5-FU mutants by comparative genomic hybridization and whole genome sequencing revealed in selected mutants the amplification of DHFR-TS and a deletion of part of chromosome 10. Point mutations in uracil phosphorybosyl transferase (UPRT), thymidine kinase (TK) and uridine phosphorylase (UP) were also observed in three individual resistant mutants. Transfection experiments confirmed that these point mutations were responsible for 5-FU resistance. Transport studies revealed that one resistant mutant was defective for uracil and 5-FU import.This study provided further insights in pyrimidine metabolism in Leishmania and confirmed that multiple mutations can co-exist and lead to resistance in Leishmania

Single-shot phase-matching free ultrashort pulse characterization based on transient absorption in solids

The frequency-resolved optical switching (FROSt) method developed for ultrashort pulse characterization is implemented for single-shot measurements. In this basic demonstration, the delay axis of the spectrogram is spatially encoded by the pump beam having a small incident angle with the photoexcited material. We present the calibration procedure for spectrograms acquired in single-shot and the temporal characterization of 44 fs pulses with central wavelength at 800 nm both in scanning and single-shot FROSt configurations. The retrieved pulses are compared by means of the root-mean-square field error. Finally, the pulses are propagated through a known dispersive material to measure the added group-delay dispersion

Chromosomal Translocations in the Parasite <i>Leishmania</i> by a MRE11/RAD50-Independent Microhomology-Mediated End Joining Mechanism

<div><p>The parasite <i>Leishmania</i> often relies on gene rearrangements to survive stressful environments. However, safeguarding a minimum level of genome integrity is important for cell survival. We hypothesized that maintenance of genomic integrity in <i>Leishmania</i> would imply a leading role of the MRE11 and RAD50 proteins considering their role in DNA repair, chromosomal organization and protection of chromosomes ends in other organisms. Attempts to generate <i>RAD50</i> null mutants in a wild-type background failed and we provide evidence that this gene is essential. Remarkably, inactivation of <i>RAD50</i> was possible in a <i>MRE11</i> null mutant that we had previously generated, providing good evidence that <i>RAD50</i> may be dispensable in the absence of <i>MRE11</i>. Inactivation of the <i>MRE11</i> and <i>RAD50</i> genes led to a decreased frequency of homologous recombination and analysis of the null mutants by whole genome sequencing revealed several chromosomal translocations. Sequencing of the junction between translocated chromosomes highlighted microhomology sequences at the level of breakpoint regions. Sequencing data also showed a decreased coverage at subtelomeric locations in many chromosomes in the <i>MRE11</i>^<i>-/-</i><i>RAD50</i>^<i>-/-</i> parasites. This study demonstrates an MRE11-independent microhomology-mediated end-joining mechanism and a prominent role for MRE11 and RAD50 in the maintenance of genomic integrity. Moreover, we suggest the possible involvement of RAD50 in subtelomeric regions stability.</p></div

Transport activities of uracil and 5-fluorouracil in <i>L. infantum</i> wild-type cells and 5-FU resistant mutants.

<p>(<b>A</b>). Transport of 5-fluorouracil (black squares) and uracil (black triangles) in <i>L. infantum</i> WT cells and in Lin5FU500.4 mutant cells (5-fluorouracil (white squares) and uracil (white triangles)) after 1, 2, 5 and 10 minutes (<b>B</b>). Transport of [³H]-uracil (white bars) competed with 200× (grey bars) or 2000× ratio (black bars) of cold uracil (left panel) or 5-FU (right panel) after a 10 minutes incubation period. (<b>C</b>). Accumulation of [³H]-5-fluorouracil in <i>L. infantum</i> WT 263 strain and in the 5-FU mutants after 10 minutes. Average of three independent biological replicates. * (p<0.05).</p

Resistance levels to 5-FU and MTX in <i>L. infantum</i> 263 WT and 5-FU resistant mutants.

*<p>Rev = revertant strain cultured without drug pressure over 30 passages;</p>**<p>(p<0,005).</p

<i>DHFR-TS</i> amplification and resistance to 5-fluorouracil.

<p>(<b>A</b>). Comparative genomic hybridization (CGH) experiments between wild-type and Lin5FU500.2 cells. Grey, equal amount of DNA between the two strains; black, increased copy number of DNA in the mutant Lin5FU500.2. (<b>B</b>). Southern blots of total digested DNAs isolated from WT and each mutant strains at 0 and 30 passages without drug were hybridized to a specific <i>DHFR-TS</i> probe. The DNA was digested to discriminate the chromosomal copy (C*) from the amplified copy (A*). (<b>C</b>). Role of <i>DHFR-TS</i> in 5-FU resistance. Growth curves of wild-type <i>L. infantum</i> parasites transfected with the expression construct pSP72<i>αHYGα- DHFR-TS</i> (black squares) or with the empty vector pSP72<i>αHYGα</i> (white squares) or the Lin5FU500.2 revertant transfected with pSP72<i>αHYGα- DHFR-TS</i> (black circles) or pSP72<i>αHYGα</i> (white circles). Average of at least three independent experiments. Transfection of <i>DHFR-TS</i> led to 5FU resistance that was statistically significant compared to mock transfectants (p<0.05).</p