Cloning and molecular characterization of cGMP-gated ion channels from rod and cone photoreceptors of striped bass ( M. saxatilis ) retina

Journal ArticleVertebrate photoreceptors respond to light with changes in membrane conductance that reflect the activity of cyclic-nucleotide gated channels (CNG channels). The functional features of these channels differ in rods and cones; to understand the basis of these differences we cloned CNG channels from the retina of striped bass, a fish from which photoreceptors can be isolated and studied electrophysiologically. Through a combination of experimental approaches, we recovered and sequenced three full-length cDNA clones. We made unambiguous assignments of the cellular origin of the clones through single photoreceptor RT-PCR. Synthetic peptides derived from the sequence were used to generate monospecific antibodies which labeled intact, unfixed photoreceptors and confirmed the cellular assignment of the various clones. In rods, we identified the channel alpha subunit gene product as 2040 bp in length, transcribed into two mRNA 1.8 kb and 2.9 kb in length and translated into a single 96-kDa protein. In cones we identified both alpha (CNGA3) and beta (CNGB3) channel subunits. For alpha, the gene product is 1956 bp long, the mRNA 3.4 kb, and the protein 74 kDa. For beta, the gene product is 2265 bp long and the mRNA 3.3 kb. Based on deduced amino acid sequence, we developed a phylogenetic map of the evolution of vertebrate rod and cone CNG channels. Sequence comparison revealed channels in striped bass, unlike those in mammals, are likely not N-linked-glycosylated as they are transported within the photoreceptor. Also bass cone channels lack certain residues that, in mammals, can be phosphorylated and, thus, affect the cGMP sensitivity of gating. On the other hand, functionally critical residues, such as positively charged amino acids within the fourth transmembrane helix (S4) and the Ca(2+)-binding glutamate in the pore loop are absolutely the same in mammalian and nonmammalian species

Ripening of plum fruit : GreenCHAINge Fruit & Vegetables WP6

Ripening of plums, from South Africa (SA), was studied following reefer transportation. In experiment 1, plum cultivars ‘Pioneer’ and ‘African Rose’ were ripened using different temperature scenarios. Both cultivars showed increased coloration during ripening, but this was much more pronounced in ‘Pioneer’ compared to ‘African Rose’. In ‘Pioneer’ there was a clear decrease in firmness during ripening; this was correlated with the temperature sum. At a temperature sum of 100-120 degree-days, the fruit had soften completely and reached the “ready–to-eat” stage. Increasing the temperature sum did not further soften the fruit. Irrespective the temperature scenario, ‘African Rose’ showed no softening and did not become “ready-to-eat”. In experiment 2, plum cultivars ‘ So ngold’ and ‘Southern Belle’ were harvested three times during their production season, transported to the Netherlands (NL), and ripening was studied at three temperatures (16, 20 and 24°C for 2 days). ‘So ngold’ was always less firm at arrival compared to ‘Southern Belle’. The applied temperatures did not have a clear effect on the speed of ripening. Fruit firmness at arrival was similar for the different batches of each cultivar; fruit from later harvest batches showed slightly more softening during storage and shelf life than fruit from first harvestbatch. Ethylene treatment (100 ppm, 24h) had effect on firmness loss in ‘Southern Belle’ when plums were ripened at higher temperature (ethylene effect was not tested in ‘So ngold’). Ethylene production in ‘Songold’ was about ten times higher than in ‘Southern Belle’ and increased during ripening in both cultivars. No clear effect of ripening temperature on ethylene production was observed

L'indemnisation du traumatisme psychique chez les vétérans : un parcours difficile

Les blessures psychiques ont été présentes au détour de chacun des conflits qui ont jalonné l’Histoire. La première partie de ce travail porte sur la découverte de la névrose traumatique, sa perception dans le cadre militaire, et sur la distinction qui existe entre l’approche psychanalytique européenne centrée sur le trauma et l’entité américaine qui s’est imposée pour se fonder essentiellement sur le stress. Les législations canadiennes et françaises qui encadrent le vétéran et l’ancien combattant atteint de psychosyndrome traumatique vont constituer le sujet de la seconde partie. L’historique du cadre juridique contemporain ; les étapes de la demande d’indemnisation avec leurs caractéristiques et leurs écueils respectifs ; les notions de preuve et d’imputabilité, enfin les particularités de l’expertise médicale sont présentées selon la perspective propre à chaque pays. Des sujets variés issus d’une trame commune qui, relatant l’expérience du vétéran blessé psychiquement pour lequel l’exercice de son droit à réparation prend l’allure d’un second combat, vont permettre de déterminer si, au-delà de la reconnaissance de l’institution ou des attentes déçues, la législation actuelle encadre de manière satisfaisante – ou pas – le droit à réparation

HIV controls the selective packaging of genomic, spliced viral and cellular RNAs into virions through different mechanisms

In addition to genomic RNA, HIV-1 particles package cellular and spliced viral RNAs. In order to determine the encapsidation mechanisms of these RNAs, we determined the packaging efficiencies and specificities of genomic RNA, singly and fully spliced HIV mRNAs and different host RNAs species: 7SL RNA, U6 snRNA and GAPDH mRNA using RT-QPCR. Except GAPDH mRNA, all RNAs are selectively encapsidated. Singly spliced RNAs, harboring the Rev-responsible element, and fully spliced viral RNAs, which do not contain this motif, are enriched in virions to similar levels, even though they are exported from the nucleus by different routes. Deletions of key motifs (SL1 and/or SL3) of the packaging signal of genomic RNA indicate that HIV and host RNAs are encapsidated through independent mechanisms, while genomic and spliced viral RNA compete for the same trans-acting factor due to the presence of the 5′ common exon containing the TAR, poly(A) and U5-PBS hairpins. Surprisingly, the RNA dimerization initiation site (DIS/SL1) appears to be the main packaging determinant of genomic RNA, but is not involved in packaging of spliced viral RNAs, suggesting a functional interaction with intronic sequences. Active and selective packaging of host and spliced viral RNAs provide new potential functions to these RNAs in the early stages of the virus life cycle

Analyse de la validité des règlements municipaux sur les bandes riveraines

Au cours des dernières années, les municipalités du Québec ont adopté des règlements sur les bandes riveraines pour combattre la prolifération de cyanobactéries dans leurs plans d’eau. Un recensement des règlements municipaux, effectué dans le bassin versant de la rivière Saint-François, a montré une grande variabilité sur le plan des mesures préconisées par les municipalités. Un cadre d’analyse permettant d’évaluer la validité de ces règlements est présenté. L’analyse se fait en deux temps soit, premièrement, en fonction des pouvoirs délégués aux municipalités, puis, dans un deuxième temps, en fonction du respect des droits acquis. Alors que certains règlements sont clairement ultra vires (par ex., l’obligation de revégétaliser), d’autres souffrent plutôt d’un déficit de légitimité (par ex., la bande riveraine de trois mètres en milieu agricole). L’atteinte d’une véritable efficience environnementale et sociétale se doit de reposer sur des assises objectives qui peuvent découler de l’application d’un test de «pertinence normative».Abstract : In recent years, Quebec municipalities have adopted by-laws relating to shore-lines in order to control the proliferation of cyanobacteria in bodies of water within their territories. A survey of municipal by-laws within the Saint-François river catchment area has revealed a great diversity of strategies adopted. In this article, a two-step analytical framework is utilized in order to assess the validity of these by-laws, commencing firstly with a discussion of the powers delegated to municipalities and then secondly, the the need to respect acquired rights. While some by-laws are clearly untra vires (e.g. the obligation to replant vegetation), others suffer from a lack of legitimacy (e.g. the requirement of a 3 meter wide shore-line in an agricultural environment). In order to be truly environmentally and societally efficient, it is felt that objective standards must be set through an application of the «normative relevance» test