Diversité et origine génétique des espèces de la sous famille des Aurantioideae et décryptage des structures interspécifiques des génomes des agrumes modernes

L'étude de l'espaceur intergénique tmL-tmF chez les espèces tunisiennes du genre Citrus montre la présence d'une seule copie du pseudogène tmF chez toutes les variétés analysées. Les valeurs positives et non significatives des tests de neutralité plaident en faveur d'un modèle d'évolution neutre et supportent l'hypothèse d'un scénario démographique stable. Nos résultats montrent clairement la contribution des pools génétiques de C. reticulata et C. maxima dans le développement des espèces secondaires tunisiennes. L'analyse basée sur les séquences nucléotidiques de huit régions génomiques chloroplastiques de 79 variétés de la sous famille des Aurantioideae révèle, via les marqueurs SNPs, une différenciation taxonomique au niveau des tribus, des soustribus, des genres et des espèces. 166 SNPs diagnostiques des 54 clades analysés ont été identifiés suivis d'une sélection de 40 KASPars. L'application de ces marqueurs chez 108 variétés montre un haut taux de transférabilité au sein de la sous famille des Aurantioideae et une cohérence avec les analyses génétiques antérieures du génome chloroplastique 21 clés marqueurs de clade catégoriquement diagnostique de 19 clades ont été identifiées. L'analyse GBS des 55 variétés d'agrumes par séquençage ILLUMINA H1SEQ2000 s'avère efficace dans d'identification des polymorphismes diagnostiques (12564 SNPs/lnDels) de la différenciation C. reticulata/C. maxima couvrant l'ensemble du génome nécessaire au déchiffrage de l'origine phylogénomique tout au long des neuf chromosomes des 55 variétés. L'approche adoptée confirme les analyses récentes basées sur des données de séquence de génome complet pour la clémentine, l'orange douce et amère et la mandarine 'Ponkan'. La technique GBS couplée à la détection des points polymorphes diagnostiques s'avère très efficace dans le décryptage des caryotypes phylogénomiques des variétés qui dérivent d'une mosaïque de deux espèces ancestrales. Le mélange C. reticulata/C. maxima doit être l'élément majeur de la variabilité phénotypique révélée élevée de ces ressources. (Résumé d'auteur

Details of antibodies used in the study.

<p>Details of antibodies used in the study.</p

Image2.PDF

<p>Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K⁺) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K_2P channels in mouse ileum and colon. Expression and distribution of the K_2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K_2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K_2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K_2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K_2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K_2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.</p

Image1.PDF

<p>Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K⁺) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K_2P channels in mouse ileum and colon. Expression and distribution of the K_2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K_2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K_2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K_2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K_2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K_2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.</p

Table1.DOCX

<p>Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K⁺) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K_2P channels in mouse ileum and colon. Expression and distribution of the K_2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K_2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K_2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K_2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K_2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K_2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.</p