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Xenopus ZFP36L1 (zinc finger protein 36, C3H type-like 1) belongs to the ZFP36 family of RNA-binding proteins, which contains two characteristic tandem CCCH-type zinc-finger domains. The ZFP36 proteins can bind AU-rich elements in 3' untranslated regions of target mRNAs and promote their turnover. However, the expression and role of ZFP36 genes during neural development in Xenopus embryos remains largely unknown. The present study showed that Xenopus ZFP36L1 was expressed at the dorsal part of the forebrain, forebrain-midbrain boundary, and midbrain-hindbrain boundary from late neurula stages to tadpole stages of embryonic development. Overexpression of XZFP36L1 in Xenopus embryos inhibited neural induction and differentiation, leading to severe neural tube defects. The function of XZP36L1 requires both its zinc finger and C terminal domains, which also affect its subcellular localization. These results suggest that XZFP36L1 is likely involved in neural development in Xenopus and might play an important role in post-transcriptional regulation. more...

Actins are a small family of ubiquitous proteins that are essential cytoskeletal components and are highly conserved during evolution. Actins are usually divided into two classes, the cytoplasmic and muscle actins, which have different functional roles. Here we systematically analyzed the actin genes in the genome of the primitive chordate amphioxus ( Branchiostoma floridae ). We found that amphioxus contains more than 30 actin genes, many of which are linked. Phylogenetic analysis suggests the amphioxus actin genes have clearly undergone extensive expansion through tandem duplications. The actin genes' structure also varies a lot, containing 2 to 7 exons. We also cloned two muscle type of actin genes from the amphioxus (B. belcheri) and compared their expression patterns during early development. The slight difference in their expression suggests functional diversification of these actin genes. Our results shed light on the evolution both of actin genes themselves and their functional roles in chordate development. more...

Neural tube defects (NTDs) are severe congenital malformation diseases, which occur in 1 out of 1000 births in human. In Xenopus , several tissue movements are involved in the neural tube closure process. Immediately after the neural tube fusion, the neural crest cells get monopolar protrusion toward dorsal midline and migrate to form the roof of the neural tube. At the same time, radial intercalation takes place from the ventral neural tube and forces it to be single-layered. Here, we physically block the neural tube closure to test the cell movements and the following patterning in Xenopus laevis explants. The results show that the single-layered neural tube fails to form and the neural crest cells remain at the lateral regions in the explants with NTDs. However, the patterning of the neural tube is not affected as indicated by the normal expression of the preneural genes. These results indicate a requirement of the neural tube fusion for the radial intercalation and the dorsal midline directed neural crest migration, but not for the dorsal-ventral patterning of the neural tube. more...

GATA factors are evolutionarily conserved and play crucial roles during embryonic development in both vertebrates and invertebrates. Vertebrate GATAs can be divided into two subgroups, the GATA1/2/3 and the GATA4/5/6 classes. Through genomic analysis, we have identified three GATA factors, representing the GATA1/2/3 and GATA4/5/6 subfamilies respectively, and one GATA like protein in the genome of the basal chordate amphioxus ( Branchiostoma floridae , cephalochordata). Partial sequence of GATA123 in the amphioxus Branchiostoma belcheri (BbGATA123) was cloned and its expression pattern during early embryonic development was studied. Expression of BbGATA123 is first detected in the mesendoderm during gastrulation. Interestingly, in the late neurula and early larva stages, it is expressed strongly in the cerebral vesicle and the mid gut region. Its expression is compared to Otx, a gene known crucial for the development of anterior structures. Our observations suggest that GATA123, together with Otx, might play an important role in the development of amphioxus cerebral vesicle, the counterpart of the vertebrate brain. more...