The Way In Which BEZ235 Slip Up On You
  • At 24 h post fertilization, wild-type (n= 13) and control-injected embryos (n= 13) displayed heart GSKJ4 rates of 90.0 �� 2.0 and 91.0 �� 2.5 beats min?1, respectively. At this time point, heart rates of MO-injected embryos (n= 15) were higher than both control groups (107.1 �� 2.8 beats min?1; P < 0.05 in both cases). Over the following 24 h, wild-type and control-injected embryonic heart rates increased significantly to 156.6 �� 3.8 beats min?1 and 152.0 �� 4.0 beats min?1, respectively. Over the same time period, MO-injected embryonic heart rate did increase significantly (P < 0.05 compared to 24 hpf), but at 48 hpf they were significantly lower (125.1 �� 3.3 beats min?1) compared to either control group (P < 0.05 in both cases). Given the current status of Danio rerio as a model of a number of human diseases, it is surprising that so little is known regarding the expression and functions of K+ channels in this organism. To date, five Kir channel genes have been identified in zebrafish (Sprague et al. 2006), of which only two have been characterized: kcnj11l (Kir6.3), which is expressed in brain (Zhang et al. 2006), and kcnj13 (Kir7.1), which is expressed selleck compound in melanophores and where loss of function of the channel gives rise to the jaguar/obelisk mutant (Iwashita et al. 2006). In comparison to our detailed knowledge of K+ channel expression and function in mammalian epithelia, virtually nothing is known about the function of such channels in freshwater fish such as Danio (Perry et al. 2003). Our sequence and phylogenetic analysis suggests that Kcnj1 is an orthologue of mammalian Kir1.1b rather than Kir1.1a or Kir1.1c, since the extended amino terminal sequence characteristic of both a and c isoforms is absent from the zebrafish protein (Fig. S1B in online Supplemental material). Structural models of both ROMK2 and Kcnj1 were created using PDB template 2qks, resolved in 2007. A previous structural model of ROMK1 (Haider et al. 2007) was itself based upon a model that is less accurate than when a resolved structural template is used. The new models described in this paper will, thus, provide a more accurate structural context with which to interpret the functional results. Heterologous expression of Kcnj1 in oocytes produced barium-sensitive and pH-dependent K+-selective currents. These basic functional properties suggest that in vivo, Kcnj1 acts as a K+ efflux pathway. Given that Kcnj1 shares 55% similarity with Kir1.1, it is not surprising that a number of functionally important phosphorylation motifs are conserved between zebrafish and the well-characterized mammalian channels (Hebert et al. 2005). The role of these motifs in the function of Kcnj1 will require further study. However, some sequence differences are noteworthy since they suggest that Kcnj1 may differ from the mammalian channels in some important regulatory features.

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