{'fraction_non_alphanumeric': 0.029675638371290544, 'fraction_numerical': 0.022774327122153208, 'mean_word_length': 5.444444444444445, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Nuclear accumulation of β‐catenin and transcription of downstream genes are regulated by zygotic Wnt5α and maternal Dsh in ascidian embryos

Nuclear β‐catenin plays crucial roles in the establishment of the embryonic axis and formation of mesendoderm tissues in ascidians and other animals. However, the cue responsible for nuclear accumulation of β‐catenin in the vegetal hemisphere is still unknown in ascidians. Here, we investigated the roles of Wnt5α and Dsh in the nuclear accumulation of β‐catenin and activation of its downstream genes in the ascidian Halocynthia roretzi. Wnt5α knockdown embryos lost nuclear accumulation of β‐catenin at the 64‐cell stage but not at the 32‐cell stage, and expression of Hr‐lim, one of the targets of β‐catenin, was impaired in the anterior region of the embryo. Zygotic Wnt5α expression in the anterior‐vegetal blastomeres was primarily responsible for these defects. Dsh knockdown showed no effect on nuclear localization of β‐catenin, but inhibited Hr‐lim expression in the posterior region. These results suggest that maintenance of nuclear Hr‐β‐catenin after the 64‐cell stage is regulated by zygotic Hr‐Wnt5α, and that expression of its target genes is modulated by both Hr‐Wnt5α and Hr‐Dsh. Our results also highlight the importance of nuclear accumulation of β‐catenin up to the 32‐cell stage through a still unclarified mechanism. Developmental Dynamics 236:1570–1582, 2007. © 2007 Wiley‐Liss, Inc.