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631.
632.
M.M. Diogo S. Ribeiro J.A. Queiroz G.A. Monteiro P. Perrin N. Tordo D.M.F. Prazeres 《Biotechnology letters》2000,22(17):1397-1400
The purification of a DNA vaccine against rabies by hydrophobic interaction chromatography (HIC) using a Sepharose gel derivatised with 1,4-butanediol diglycidyl ether was scaled up 60 times. The purification profile was not affected by increased loadings (up to 15 mg DNA) and a product with a consistent quality was obtained. Fourteen mg of plasmid with an HPLC purity of 100% were obtained in one run, corresponding to a 95% yield. 相似文献
633.
Natalie C. Bamford Brendan D. Snarr Fabrice N. Gravelat Dustin J. Little Mark J. Lee Caitlin A. Zacharias Josée C. Chabot Alexander M. Geller Stefanie D. Baptista Perrin Baker Howard Robinson P. Lynne Howell Donald C. Sheppard 《The Journal of biological chemistry》2015,290(46):27438-27450
Aspergillus fumigatus is the most virulent species within the Aspergillus genus and causes invasive infections with high mortality rates. The exopolysaccharide galactosaminogalactan (GAG) contributes to the virulence of A. fumigatus. A co-regulated five-gene cluster has been identified and proposed to encode the proteins required for GAG biosynthesis. One of these genes, sph3, is predicted to encode a protein belonging to the spherulin 4 family, a protein family with no known function. Construction of an sph3-deficient mutant demonstrated that the gene is necessary for GAG production. To determine the role of Sph3 in GAG biosynthesis, we determined the structure of Aspergillus clavatus Sph3 to 1.25 Å. The structure revealed a (β/α)8 fold, with similarities to glycoside hydrolase families 18, 27, and 84. Recombinant Sph3 displayed hydrolytic activity against both purified and cell wall-associated GAG. Structural and sequence alignments identified three conserved acidic residues, Asp-166, Glu-167, and Glu-222, that are located within the putative active site groove. In vitro and in vivo mutagenesis analysis demonstrated that all three residues are important for activity. Variants of Asp-166 yielded the greatest decrease in activity suggesting a role in catalysis. This work shows that Sph3 is a glycoside hydrolase essential for GAG production and defines a new glycoside hydrolase family, GH135. 相似文献
634.
Barret C. Phillips Nicolas Rodrigues Alexandra Jansen van Rensburg Nicolas Perrin 《Evolution; international journal of organic evolution》2020,74(3):644-654
Sex chromosomes in vertebrates range from highly heteromorphic (as in most birds and mammals) to strictly homomorphic (as in many fishes, amphibians, and nonavian reptiles). Reasons for these contrasted evolutionary trajectories remain unclear, but species such as common frogs with polymorphism in the extent of sex chromosome differentiation may potentially deliver important clues. By investigating 92 common frog populations from a wide range of elevations throughout Switzerland, we show that sex chromosome differentiation strongly correlates with alleles at the candidate sex-determining gene Dmrt1. Y-specific Dmrt1 haplotypes cluster into two main haplogroups, YA and YB, with a phylogeographic signal that parallels mtDNA haplotypes: YA populations, with mostly well-differentiated sex chromosomes, occur primarily south of the main alpine ridge that bisects Switzerland, whereas YB populations, with mostly undifferentiated (proto-)sex chromosomes, occur north of this ridge. Elevation has only a marginal effect, opposing previous suggestions of a major role for climate on sex chromosome differentiation. The Y-haplotype effect might result from differences in the penetrance of alleles at the sex-determining locus (such that sex reversal and ensuing X-Y recombination are more frequent in YB populations), and/or fixation of an inversion on YA (as supported by the empirical observation that YA haplotypes might not recombine in XYA females). 相似文献
635.
Fredrik RM Huss Erika Nyman Carl-Johan Gustafson Katrin Gisself?lt Elisabeth Liljensten Gunnar Kratz 《Organogenesis》2008,4(3):195-200
Full thickness skin wounds in humans heal with scars, but without regeneration of the dermis. A degradable poly(urethane urea) scaffold (PUUR), Artelon® is already used to reinforce soft tissues in orthopaedics, and for treatment of osteoarthritis of the hand, wrist and foot. In this paper we have done in vitro experiments followed by in vivo studies to find out whether the PUUR is biocompatible and usable as a template for dermal regeneration. Human dermal fibroblasts were cultured on discs of PUUR, with different macrostructures (fibrous and porous). They adhered to and migrated into the scaffolds, and produced collagen. The porous scaffold was judged more suitable for clinical applications and 4 mm Ø, 2 mm-thick discs of porous scaffold (12% w/w or 9% w/w polymer solution) were inserted intradermally in four healthy human volunteers. The implants were well tolerated and increasing ingrowth of fibroblasts was seen over time in all subjects. The fibroblasts stained immunohistochemically for procollagen and von Willebrand factor, indicating neocollagenesis and angiogenesis within the scaffolds. The PUUR scaffold may be a suitable material to use as a template for dermal regeneration.Key words: dermal regeneration, tissue engineering, polymer scaffold, wound healing, in vitro, in vivo, guided tissue regeneration, human, burns 相似文献
636.
Christophe Dufresnes Ilias Strachinis Nataliia Suriadna Galyna Mykytynets Dan Coglniceanu Paul Szkely Tanja Vukov Jan W. Arntzen Ben Wielstra Petros Lymberakis Eli Geffen Sarig Gafny Yusuf Kumluta etin Ilgaz Kamil Candan Edvrd Mizsei Mrton Szabolcs Krzysztof Kolenda Nazar Smirnov Philippe Gniez Simeon Lukanov Pierre‐Andr Crochet Sylvain Dubey Nicolas Perrin Spartak N. Litvinchuk Mathieu Denoël 《Molecular ecology》2019,28(13):3257-3270
Cryptic phylogeographic diversifications provide unique models to examine the role of phylogenetic divergence on the evolution of reproductive isolation, without extrinsic factors such as ecological and behavioural differentiation. Yet, to date very few comparative studies have been attempted within such radiations. Here, we characterize a new speciation continuum in a group of widespread Eurasian amphibians, the Pelobates spadefoot toads, by conducting multilocus (restriction site associated DNA sequencing and mitochondrial DNA) phylogenetic, phylogeographic and hybrid zone analyses. Within the P. syriacus complex, we discovered species‐level cryptic divergences (>5 million years ago [My]) between populations distributed in the Near‐East (hereafter P. syriacus sensu stricto [s.s.]) and southeastern Europe (hereafter P. balcanicus), each featuring deep intraspecific lineages. Altogether, we could scale hybridizability to divergence time along six different stages, spanning from sympatry without gene flow (P. fuscus and P. balcanicus, >10 My), parapatry with highly restricted hybridization (P. balcanicus and P. syriacus s.s., >5 My), narrow hybrid zones (~15 km) consistent with partial reproductive isolation (P. fuscus and P. vespertinus, ~3 My), to extensive admixture between Pleistocene and refugial lineages (≤2 My). This full spectrum empirically supports a gradual build up of reproductive barriers through time, reversible up until a threshold that we estimate at ~3 My. Hence, cryptic phylogeographic lineages may fade away or become reproductively isolated species simply depending on the time they persist in allopatry, and without definite ecomorphological divergence. 相似文献
637.
Pietro Tedesco Marco Visone Ermenegilda Parrilli Maria Luisa Tutino Elena Perrin Isabel Maida Renato Fani Francesco Ballestriero Radleigh Santos Clemencia Pinilla Elia Di Schiavi George Tegos Donatella de Pascale 《PloS one》2015,10(11)
This study investigated the relationship between host efflux system of the non-vertebrate nematode Caenorhabditis elegans and Burkholderia cepacia complex (Bcc) strain virulence. This is the first comprehensive effort to profile host-transporters within the context of Bcc infection. With this aim, two different toxicity tests were performed: a slow killing assay that monitors mortality of the host by intestinal colonization and a fast killing assay that assesses production of toxins. A Virulence Ranking scheme was defined, that expressed the toxicity of the Bcc panel members, based on the percentage of surviving worms. According to this ranking the 18 Bcc strains were divided in 4 distinct groups. Only the Cystic Fibrosis isolated strains possessed profound nematode killing ability to accumulate in worms’ intestines. For the transporter analysis a complete set of isogenic nematode single Multidrug Resistance associated Protein (MRP) efflux mutants and a number of efflux inhibitors were interrogated in the host toxicity assays. The Bcc pathogenicity profile of the 7 isogenic C. elegans MRP knock-out strains functionality was classified in two distinct groups. Disabling host transporters enhanced nematode mortality more than 50% in 5 out of 7 mutants when compared to wild type. In particular mrp-2 was the most susceptible phenotype with increased mortality for 13 out 18 Bcc strains, whereas mrp-3 and mrp-4 knock-outs had lower mortality rates, suggesting a different role in toxin-substrate recognition. The use of MRP efflux inhibitors in the assays resulted in substantially increased (>40% on average) mortality of wild-type worms. 相似文献
638.
Tatiana Selchenkova Clément Fran?ois Daniele Sch?n Alexandra Corneyllie Fabien Perrin Barbara Tillmann 《PloS one》2014,9(11)
The present study investigated whether a temporal hierarchical structure favors implicit learning. An artificial pitch grammar implemented with a set of tones was presented in two different temporal contexts, notably with either a strongly metrical structure or an isochronous structure. According to the Dynamic Attending Theory, external temporal regularities can entrain internal oscillators that guide attention over time, allowing for temporal expectations that influence perception of future events. Based on this framework, it was hypothesized that the metrical structure provides a benefit for artificial grammar learning in comparison to an isochronous presentation. Our study combined behavioral and event-related potential measurements. Behavioral results demonstrated similar learning in both participant groups. By contrast, analyses of event-related potentials showed a larger P300 component and an earlier N2 component for the strongly metrical group during the exposure phase and the test phase, respectively. These findings suggests that the temporal expectations in the strongly metrical condition helped listeners to better process the pitch dimension, leading to improved learning of the artificial grammar. 相似文献
639.
640.
Christophe?Dufresnes Lionel?Di?Santo Julien?Leuenberger Johan?Schuerch Glib?Mazepa Nathalie?Grandjean Daniele?Canestrelli Nicolas?Perrin Sylvain?DubeyEmail author 《Biological invasions》2017,19(5):1407-1420
Human introductions of exotic amphibians can have catastrophic effects on native species. However, they usually remain unnoticed without genetic tools when species are difficult to distinguish morphologically. In Western Europe, pool frogs (Pelophylax sp.) make a worrisome case: recent genetic data showed the presence of Italian (Pelophylax bergeri) mtDNA haplotypes within the range of the threatened European Pelophylax lessonae, two morphologically similar taxa. Here we conduct a multilocus phylogeographic and population genetic survey of European and Italian pool frogs (combining present and historic samples), to investigate the origin(s) and consequences of potential introductions. Results are unequivocal: we show that the alien P. bergeri have extensively invaded France and north-Alpine Switzerland, and have also deeply introgressed with P. lessonae, which has led to the complete replacement of most populations. Alien specimens have probably been translocated multiple times from Central Italy at least prior to the 1960s. Based on our dense sampling, only two areas, north and south of the Alps still host native pool frogs in Switzerland, the Joux Valley near the French border and the canton of Ticino, respectively. Importantly, we show that these last P. lessonae populations are remnants of a private genetic diversity specific to Western Europe, which vanished during the P. bergeri’s invasion. Our study emphasizes the risk of genetic pollution during invasion by human-introduced taxa and brings alarming concern regarding uncontrolled amphibian translocations. Moreover, it demonstrates the necessity for genetic surveys to detect and monitor these invasions, especially where species determination is problematic. 相似文献