Search

The synuclein family consists of three small intracellular proteins mainly expressed in neural tissues, and has been associated with human neurodegenerative diseases. We have examined the spatial and temporal expression patterns of three synuclein genes during embryogenesis of Xenopus laevis. The Xenopus synucleins were firstly expressed in the developing nervous system at the tail bud stages. At tadpole stages, Xenopus snca was expressed in the brain, branchial arch and somite, and sncbb signals were detected in entire brain and spinal cord. However, sncg was only expressed in the peripheral nervous system including trigeminal nerve and dorsal root ganglion. RT-PCR indicated that expression of synucleins was up-regulated at the end of neurulation, and then maintained at later examined stages. Our study provides the spatiotemporal expression patterns of the synuclein family genes in Xenopus embryos, and forms a basis for further functional analysis of synucleins., (Copyright © 2011 Wiley-Liss, Inc.)

The interaction between early proneural genes and lateral inhibition determines the number of primary neurons. The mechanism for regulating the size of the proneural domain, however, has not been clarified. We show here that inhibition of the function of XETOR in Xenopus, a homolog of human oncoprotein ETO/MTG8, leads to a neurogenic phenotype of expanded proneural domain without alteration in the density of primary neurons. This result suggests that XETOR is a prerequisite for regulating the size of the proneural domain. We further show that such a regulation is accomplished by establishing a negative feedback loop between XETOR and proneural genes except Xngnr-1, as well as by antagonism between XETOR and lateral inhibition., (Copyright 2002 Elsevier Science Ireland Ltd.)

We identified a novel cDNA, XCL-2, encoding an m-type calpain, a calcium-dependent intracellular protease. This protein has all characteristic structures and active sites of canonical calpains. Zygotic transcription of the gene was first detected at stage 10. It is expressed exclusively in the ventral circumblastoporal collar and the mesoderm-free zone at the most anterior tip of neural fold in late gastrulae and neurulae. In later stages, expression is only found in cement gland and proctodeum. It is also expressed in a tissue-specific manner. In adult tissues, various levels of expression were detected in brain, eye, heart, intestine, kidney, lung, stomach and testis, but not in liver, muscle, nerve, ovary, skin and spleen. Overexpression of wild-type XCL-2 suggests that this gene is involved in gastrulation movement and convergent extension during gastrulation and neurulation. Overexpression of a dominant-negative mutant caused a phenotype morphologically similar to, but histologically different from, that caused by overexpression of wild-type XCL-2. The mutant phenotype can be rescued by injection of wild-type XCL-2. These data suggest that XCL-2 plays an important role in convergent extension movements during embryogenesis in Xenopus laevis. [ABSTRACT FROM AUTHOR]

We have isolated a full-length cDNA encoding Xenopus L-arginine:glycine amidinotransferase (XAT), which shares a highly conserved sequence with human, chick and rat amidinotransferase. Although there are some studies about its structure and function in energy metabolism of adult tissues in some other species, little is known about its roles during early embryonic development. Characterization of embryonic expression indicates that XAT is differentially expressed around the yolk plug including the dorsal blastopore area at early gastrula stages and is extensively expressed in the midline of the neural plate of early neurula stages. Sections reveal that its transcripts are located in the notochord. In the tailbud stage signals are found both in the notochord and trunk area, whereas only faint signals can be found in the cephalic part. [ABSTRACT FROM AUTHOR]

The ontogeny and localization of crystallins during free lens development (i.e. lens development without the optic vesicle) were investigated in Xenopus laevis using the indirect immunofluorescence staining method with an antiserum raised against homologous total lens soluble proteins. Since the developing free lenses pass through stages similar to those of the lenses regenerated from the inner cell layer of the outer cornea following lentectomy in the same species Freeman's classification was used to identify the stages of free lens development. The first appearance of a positive reaction occurred at early stage IV in a number of cells in an area where future lens fibre cells would develop. With further differentiation of the free lens more and more cells in the fibre area started to show a positive reaction and the first positive reaction in the epithelium was observed late in stage V. Histological examination revealed that a fully differentiated free lens and a normally developed lens are similar but that the free lens is smaller. [ABSTRACT FROM AUTHOR]