11-P006 Ancient animal homeobox genes, in a novel chordate context
نویسندگان
چکیده
Internal organs in vertebrates show distinctive left–right asymmetry. To establish left–right patterning, creation of a leftward flow plays a critical role. However, how this flow function or how this flow is sensed is still debated, because a flow sensor itself has not been identified yet. Here we show a medaka mutant abecobe (abc), isolated by our recent ENU-mediated mutagenesis screening with medaka (Japanese killifish). abc displays a reversal of left–right polarity in organ positioning in the half of the homozygotes. The asymmetric expression of the sided genes, southpaw, lefty and charon, is randomized in abc, indicating that abc acts upstream of these early asymmetric genes. The leftward flow generated by rotating cilia in Kupffer’s vesicle (KV), the first sign of symmetry breaking, is, however, normal in abc. By positional cloning, we have identified abc as the medaka homolog of human PKD1L1, which encodes a transmembrane protein of unknown function and has homology with polycystins. Polycystin-1 is thought to act as a mechanosensor to detect fluid flow in the kidney. The expression of pkd1l1 is confined to KV. This candidate gene was also found to be mutated in the other abc allele. These results suggest that the abc gene is crucially involved in the formation of left–right asymmetry downstream of leftward flow, and may function as a sensor of the leftward flow. We believe that further analysis of Abc function will provide insights into a molecular link between leftward flow and the asymmetric gene expression.
منابع مشابه
Ancient homeobox gene loss and the evolution of chordate brain and pharynx development: deductions from amphioxus gene expression
Homeobox genes encode a large superclass of transcription factors with widespread roles in animal development. Within chordates there are over 100 homeobox genes in the invertebrate cephalochordate amphioxus and over 200 in humans. Set against this general trend of increasing gene number in vertebrate evolution, some ancient homeobox genes that were present in the last common ancestor of chorda...
متن کاملDispersal of NK homeobox gene clusters in amphioxus and humans.
The Drosophila melanogaster genome has six physically clustered NK-related homeobox genes in just 180 kb. Here we show that the NK homeobox gene cluster was an ancient feature of bilaterian animal genomes, but has been secondarily split in chordate ancestry. The NK homeobox gene clusters of amphioxus and vertebrates are each split and dispersed at two equivalent intergenic positions. From the a...
متن کاملEvidence for 14 homeobox gene clusters in human genome ancestry
The arrangement of Hox genes into physical clusters is fundamental to the patterning of animal body plans. Other homeobox genes are often described as dispersed, with only occasional examples of linkage reported, such as the amphioxus ParaHox and Drosophila 93D/E clusters. This clustering is unlikely to be the derived condition, as the genes of the ParaHox and 93D/E clusters are phylogeneticall...
متن کاملReinforcing the Egg-Timer: Recruitment of Novel Lophotrochozoa Homeobox Genes to Early and Late Development in the Pacific Oyster
The metazoan superclade Lophotrochozoa includes mollusks, annelids, and several other animal phyla. It is reasonable to assume that this organismal diversity may be traced, in part, to changes in developmentally important genes, such as the homeobox genes. Although most comparative studies have focussed on ancient homeobox gene families conserved across bilaterians, there are also "novel" homeo...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Mechanisms of Development
دوره 126 شماره
صفحات -
تاریخ انتشار 2009