Savings and extinction of conditioned eyeblink responses in fragile X syndrome

The fragile X syndrome (FRAXA) is the most widespread heritable form of mental retardation caused by the lack of expression of the fragile X mental retardation protein (FMRP). This lack has been related to deficits in cerebellum-mediated acquisition of conditioned eyelid responses in individuals with FRAXA. In the present behavioral study, long-term effects of deficiency of FMRP were investigated by examining the acquisition, savings and extinction of delay eyeblink conditioning in male individuals with FRAXA. In the acquisition experiment, subjects with FRAXA displayed a significantly poor performance compared with controls. In the savings experiment performed at least 6 months later, subjects with FRAXA and controls showed similar levels of savings of conditioned responses. Subsequently, extinction was faster in subjects with FRAXA than in controls. These findings confirm that absence of the FMRP affects cerebellar motor learning. The normal performance in the savings experiment and aberrant performance in the acquisition and extinction experiments of individuals with FRAXA suggest that different mechanisms underlie acquisition, savings and extinction of cerebellar motor learning

Characterization of sulfer metabolizing microbes in a cold saline microbial mat of the Canadian High Artic

The Gypsum Hill (GH) spring system is located on Axel Heiberg Island of the High Arctic, perennially discharging cold hypersaline water rich in sulfur compounds. Microbial mats are found adjacent to channels of the GH springs. This thesis is the first detailed analysis of the Gypsum Hill spring microbial mats and their microbial diversity. Physicochemical analyses of the water saturating the GH spring microbial mat show that in summer it is cold (9°C), hypersaline (5.6%), and contains sulfide (0-10 ppm) and thiosulfate (>50 ppm). Pyrosequencing analyses were carried out on both 16S rRNA transcripts (i.e. cDNA) and genes (i.e. DNA) to investigate the mat's community composition, diversity, and putatively active members. In order to investigate the sulfate reducing community in detail, the sulfite reductase gene and its transcript were also sequenced. Finally, enrichment cultures for sulfate/sulfur reducing bacteria were set up and monitored for sulfide production at cold temperatures. Overall, sulfur metabolism was found to be an important component of the GH microbial mat system, particularly the active fraction, as 49% of DNA and 77% of cDNA from bacterial 16S rRNA gene libraries were classified as taxa capable of the reduction or oxidation of sulfur compounds. Major components of the bacterial libraries are Gamma-, Epsilon-, and Deltaproteobacteria, Flavobacteriia, and Actinobacteria. The GH microbial mat community appears to be highly influenced by the microorganisms present in the upstream GH spring sediment. Close investigation of archaeal species and sulfate reducing bacteria within the mat revealed the presence of enigmatic phyla for which no representatives have yet been isolated. In addition to sulfate reducing bacteria, a variety of elemental sulfur reducing bacteria were detected from the GH microbial mat, including Desulfuromusa, Desulfuromonas, and Sulfurospirillum. As well, cultures enriched with either elemental sulfur, thiosulfate, or sulfate, and inoculated with sediments from Axel Heiberg sulfidic spring sediments generally showed sulfide at low temperatures (5°C and 10°C), indicating that many different sulfur compounds may be metabolised within the springs.Le système de source de Gypsum Hill (GH) est situé sur l'île d'Axel Heiberg dans le Haut-Arctique, et évacue perpétuellement de l'eau hypersaline, froide et riche en composés soufrés. Les tapis microbiens se trouvent à côté des canaux de source GH. Cette thèse est la première analyse détaillée des tapis microbiens de source Gypsum Hill et leur diversité microbienne. Des analyses physico-chimiques de l'eau saturant le tapis microbiens de source GH montrent que durant l'été il est froid (9 ° C), hypersalin (5,6%), et contient du sulfure (0-10 ppm) et du thiosulfate (> 50 ppm). Des analyses en pyroséquençage ont été effectuées sur les transcriptions ARNr 16S (c.-à-ADNc) et sur des gènes (c.-à-ADN) pour enquêter sur la composition des communautés du tapis, de sa diversité, et des membres présumés actifs. Afin d'étudier la communauté réductrice de sulfate en détail, le gène de la réductase sulfite et sa transcription ont également été séquencés. Enfin, des cultures d'enrichissement pour les bactéries réductrices de soufre/sulfate ont été mises en place et suivies pour la production de sulfure à des températures froides. Dans l'ensemble, le métabolisme du soufre s'est trouvé être un élément important du système de tapis microbien GH, en particulier la fraction active, étant donne que 49% de l'ADN et de 77% de l'ADNc de banques bactériennes de gènes ARNr 16S ont été classés comme étant un taxon capable de la réduction ou l'oxydation des composés de soufre. Les principaux éléments des banques bactériennes sont Gamma-, Epsilon, et Deltaproteobacteria, Flavobacteriia et Actinobacteria. La communauté de tapis microbien GH semble être fortement influencée par les micro-organismes présents en amont de sédiments des sources GH. Des enquêtes fermées d'espèces d'archées et des bactéries réductrices de sulfate dans le tapis microbien ont révélé la présence d'embranchements énigmatique pour laquelle aucun représentant n'a encore été isolé. En plus de bactéries sulfato-réductrices, une variété de bactéries réductrices de soufre élémentaire ont été détectés à partir du tapis microbien GH, y compris Desulfuromusa, Desulfuromonas, et Sulfurospirillum. Aussi, des cultures enrichies avec soit du soufre élémentaire, thiosulfate, ou du sulfate, et inoculé avec les sédiments provenant des sédiments des sources sulfurées d'Axel Heiberg montrent généralement du sulfure à basse température (5 ° C et 10 ° C), ce qui indique que de nombreux différents composés soufrés peuvent être métabolisés à l'intérieur des ressorts

Evidence of in situ microbial activity and sulphidogenesis in perennially sub-0 \ub0C and hypersaline sediments of a high Arctic permafrost spring

The lost hammer (LH) spring perennially discharges subzero hypersaline reducing brines through thick layers of permafrost and is the only known terrestrial methane seep in frozen settings on Earth. The present study aimed to identify active microbial communities that populate the sediments of the spring outlet, and verify whether such communities vary seasonally and spatially. Microcosm experiments revealed that the biological reduction of sulfur compounds (SR) with hydrogen (e.g., sulfate reduction) was potentially carried out under combined hypersaline and subzero conditions, down to 1220 \ub0C, the coldest temperature ever recorded for SR. Pyrosequencing analyses of both 16S rRNA (i.e., cDNA) and 16S rRNA genes (i.e., DNA) of sediments retrieved in late winter and summer indicated fairly stable bacterial and archaeal communities at the phylum level. Potentially active bacterial and archaeal communities were dominated by clades related to the T78 Chloroflexi group and Halobacteria species, respectively. The present study indicated that SR, hydrogenotrophy (possibly coupled to autotrophy), and short-chain alkane degradation (other than methane), most likely represent important, previously unaccounted for, metabolic processes carried out by LH microbial communities. Overall, the obtained findings provided additional evidence that the LH system hosts active communities of anaerobic, halophilic, and cryophilic microorganisms despite the extreme conditions in situ.Peer reviewed: YesNRC publication: Ye