The International Journal of Developmental Biology

Euskal Herriko Unibertsitateko Argitalpen Zerbitzua/Servicio Editorial de la Universidad del País Vasco.

Vol. 52/7, 2008                                         Más información

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Contents                                                           

In Memoriam of Prof. Jacques Signoret
Yannick Andéol, Alain Collenot and Jacques Lefresne
Int. J. Dev. Biol. (2008) 52: 797-799 

“Laboratoire de Biologie du Développement”, UMR CNRS 7622, Université Pierre et Marie Curie, Paris, France.

ABSTRACT:  Professor Jacques Signoret died last July 2007 at the age of 75. He was a physicist, a naturalist, an eminent embryologist possessing an impressive knowledge and a distinguished teacher. His name has become internationally associated with “Transition Blastuléenne” (Blastulean Transition) which he defined for the first time in 1971 in the urodele Axolotl. Jacques Signoret started his scientific carrier in Paris, first in 1952 as Assistant Professor of Physics in Pr. Louis Leprince-Ringuet’s laboratory, then in 1954 as Assistant Professor of Embryology at the Paris University of Science under the leadership of Pr. Louis Gallien. Research fellowships from NATO allowed him to carry out two post-doctoral positions in the USA, first in 1959 at the California Institute of Technology in Albert Tyler’s laboratory and in 1960 at the Indiana University in Robert Briggs’s laboratory where he succeeded in performing for the first time nuclear transplantations in Axolotl. He came back to France in 1962, bringing back the Axolotl as a laboratory model and was appointed Professor of Embryology at the University of Caen where he taught until 1998.....(continued)

 
Meeting Report

Pluripotency and differentiation in embryos and stem cells - Pavia, 17-18 January 2008
James A. Adjaye 1, Anne G. Byskov 2, Jose B. Cibelli 3, Ruggero De Maria 4, Stephen Minger 5, Maurilio Sampaolesi 6,7, Giuseppe Testa 8, Catherine Verfaillie 9, Magdalena Zernicka-Goetz 10, Hans Schöler 11, Michele Boiani 11, Nicola Crosetto 12 and Carlo A. Redi 13.
Int. J. Dev. Biol. (2008) 52: 801-809

ABSTRACT:  Each year many scientific meetings are held on stem cells to appraise the state of knowledge on their potency, differentiation and applications. So why did we hold another meeting? Because we thought one aspect was not adequately addressed in the others. When thinking of how our body is derived from a single fertilized egg, it is self-evident that the embryo is the ‘mother’ of all stem cells. This fact is probably overlooked because it is so remote (decades back in our lives!) and because embryonic stem cells do not exist as such in the embryo. However, this also tends to be ignored on purpose in many stem cell meetings because working on (human) embryos brings up substantial ethical concerns that bear on the scientific undertaking like nothing else. The origin of stem cells has become even more of a sensitive issue since the discovery in 2006 that embryonic stem (ES) cell-like cells can be generated in a petri dish straight from somatic cells by retrovirus-mediated transfer of selected genes. These new cells have been named ‘induced pluripotent stem‘ (iPS) cells and have been obtained without any egg or embryo consumption (Takahashi and Yamanaka, 2006). This leads to the first topic of our meeting: natural and induced pluripotency...

Key words: embryo, cancer, differentiation, pluripotency, stem cell, meeting report

*Corresponding author e-mail: mboiani@mpi-muenster.mpg.de

 
Essay

The enigmatic role of the ankyrin repeat domain 1 gene in heart development and disease
Alexander T. Mikhailov* and Mario Torrado
Int. J. Dev. Biol. (2008) 52: 811-821

Developmental Biology Group, Institute of Health Sciences, University of La Coruña, La Coruña, Spain

ABSTRACT: It has been proposed that the ankyrin repeat domain 1 (ANKRD1) factor (also known as CARP) plays a critical role in transcriptional regulation, myofibrillar assembly and stretch sensing during heart development and cardiac insults. ANKRD1/CARP has also been reported to negatively regulate cardiac gene expression in cell-based promoter-reporter assays. Consequently, rapid up-regulation of the ankrd1 gene in myocardium in response to developmental stimuli or pathological insults has tended to be interpreted in the context of the inhibitory effects of ANKRD1 on cardiomyocyte gene expression. Surprisingly, a total ankrd1 knockout resulted in a complete lack of phenotype, suggesting that ANKRD1/CARP is not crucial for regulation of cardiac gene expression in vivo. In this essay, we summarize (1) the accumulated evidence for the apparent multifunctional properties of this enigmatic protein, (2) the distinct chamber-dependent regulation of ankrd1 expression patterns in the heart, both during development and cardiac injury, and (3) ANKRD1 involvement in networks regulating adaptation of the myocardium to stress. Whenever feasible, we present the results obtained in patients together with those obtained in the relevant animal and cellular models. A close examination of the findings still fails to define ANKRD1 as a negative regulator of cardiac gene expression in vivo, but rather indicates that its augmented expression can represent an adaptive response of the myocardium to stress both during development and various heart insults.

Key words: CARP, heart development, heart failure, stress-responsive regulator, expression patterns

*Corresponding author e-mail: margot@udc.es

 
Reviews

Genes controlling pancreas ontogeny
Claire Bonal and Pedro L. Herrera*
Int. J. Dev. Biol. (2008) 52: 823-835

Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland

ABSTRACT: The pancreas develops from two separate and independent endodermal primordia. The molecular events supporting the early morphological changes that give rise to the formation of the dorsal and ventral pancreatic buds result from coordinated responses to extrinsic and intrinsic signals. The extrinsic signals are involved in processes dictating whether progenitor cells remain as immature or as committed precursors. After specification, the sequential activation of transcription factors determines cell autonomously the commitment and differentiation of these progenitors. During pancreas development, the roles of extrinsic and intrinsic signals are variable, depending on the particular competence of each progenitor cell. We summarize in this review the main events, at the level of gene expression, which are involved in the early stages of pancreas development.

Key words: islet, pancreas, progenitor, endocrine, development, beta cell

*Corresponding author e-mail: pedro.herrera@medecine.unige.ch

Sex-determining mechanisms in insects
Lucas Sánchez
Int. J. Dev. Biol. (2008) 52: 837-856 

Centro de Investigaciones Biológicas (C.S.I.C), Madrid, Spain

ABSTRACT: Sex determination refers to the developmental programme that commits the embryo to either the male or the female pathway. The animal kingdom possesses a wealth of mechanisms via which gender is decided, all of which are represented among the insects. This manuscript focuses on a number of insects for which genetic and molecular data regarding sex determination mechanisms are available. The sex determination genetic cascade of Drosophila melanogaster is first discussed, followed by an analysis of the sex determination genes of other dipteran and non-dipteran insects. Representative examples of sex determination mechanisms that differ in their primary signal are also described. Finally, some evolutionary aspects of these mechanisms are discussed.

Key words: Drosophila, Apis, Sciarids, Coccids, heterochromatisation, chromosome elimination

*Corresponding author e-mail: lsanchez@cib.csic.es

The Apical Ectodermal Ridge: morphological aspects and signaling pathways
Marian Fernandez-Teran 1 and Maria A. Ros*2.
Int. J. Dev. Biol. (2008) 52: 857-871

1: Departamento de Anatomía y Biología Celular. Universidad de Cantabria.  2: Instituto de Biomedicina y Biotecnología de Cantabria, IBBTEC (CSIC-UC-IDICAN), Santander, Spain.

ABSTRACT: The Apical Ectodermal Ridge (AER) is one of the main signaling centers during limb development. It controls outgrowth and patterning in the proximo-distal axis. In the last few years a considerable amount of new data regarding the cellular and molecular mechanisms underlying AER function and structure has been obtained. In this review, we describe and discuss current knowledge of the regulatory networks which control the induction, maturation and regression of the AER, as well as the link between dorso-ventral patterning and the formation and position of the AER. Our aim is to integrate both recent and old knowledge to produce a wider picture of the AER which enhances our understanding of this relevant structure.

Key words: apical ectodermal ridge, AER, limb development, FGF, dorso-ventral patterning, double ridge

*Corresponding author e-mail: rosm@unican.es
 
Original Articles

Developmentally regulated expression of hemoglobin subunits in avascular tissues
Fiona C. Mansergh 1,2,  Susan M. Hunter 1,  Jenny C. Geatrell 3,  Miguel Jarrin 3,  Kate Powell 3,  Martin J. Evans 1 and Michael A. Wride* 3,4.
Int. J. Dev. Biol. (2008) 52: 873-886 

1: Cardiff School of Biosciences, Cardiff University, Wales, UK.  2: Smurfit Institute of Genetics, Trinity College Dublin, Ireland.  3: School of Optometry and Vision Sciences, Cardiff University, Wales, UK.  4: Ocular Development and Neurobiology Research Group, Department of Zoology, School of Natural Sciences, Trinity College Dublin, Ireland.

ABSTRACT: We investigated the spatio-temporal profile of hemoglobin subunit expression in developing avascular tissues. Significant up-regulation of hemoglobin subunits was identified in microarray experiments comparing blastocyst inner cell masses with undifferentiated embryonic stem (ES) cells. Hemoglobin expression changes were confirmed using embryoid bodies (derived from in vitro differentiation of ES cells) to model very early development at pre-vascular stages of embryogenesis; i.e. prior to hematopoiesis. We also demonstrate, using RT-PCR, Western blotting and immunocytochemistry, expression of adult and fetal mouse hemoglobin subunits in the avascular ocular lens at various stages of development and maturation. Hemoglobin proteins were expressed in lens epithelial cells (cytoplasmic) and cortical lens fiber cells (nuclear and cell-surface-associated); however, a sensitive heme assay demonstrated negligible levels of heme in the developing lens postnatally. Hemoglobin expression was also observed in the developing eye in corneal endothelium and retinal ganglion cells. Gut sections showed, in addition to erythrocytes, hemoglobin protein staining in rare, individual villus epithelial cells. These results suggest a paradigm shift: hemoglobin subunits are expressed in the avascular lens and cornea and in pre-hematopoietic embryos. It is likely, therefore, that hemoglobin subunits have novel developmental roles; the absence of the heme group from the lens would indicate that at least some of these functions may be independent of oxygen metabolism. The pattern of expression of hemoglobin subunits in the perinuclear region during lens fiber cell differentiation, when denucleation is taking place, may indicate involvement in the apoptosis-like signaling processes occurring in differentiating lens fiber cells.

Key words: hemoglobin, lens, differentiation, embryoid body, stem cell

*Corresponding author e-mail: wridem@tcd.ie

A histone H1 variant is required for erythrocyte maturation in medaka
Osamu Matsuoka 1,  Norihisa Shindo 2,  Daisuke Arai and Toru Higashinakagawa*1.
Int. J. Dev. Biol. (2008) 52: 887-892

1: Center for Advanced Life and Medical Science, Waseda University, Tokyo, Japan.  2: Department of Experimental Pathology, Cancer Institute of the Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan

ABSTRACT: Three histone H1 variants were identified in medaka fish and their sequence characteristics were analyzed. This paper reports one of these variants, termed H1-2, because of its possible implication in erythrocyte maturation. The amino acid sequence of H1-2 was phylogenetically similar to that of other replication-dependent histones. The mRNA transcribed from the h1-2 gene, however, possessed a poly(A) tail without a stem-loop structure, indicating that H1-2 may represent a replication-independent (RI) histone. Transcripts from the h1-2 gene were largely localized in erythrocytes, and knock-down of the h1-2 gene with morpholino antisense oligos resulted in failure to develop mature erythrocytes. In the morphants, residual erythrocytes showed severely impaired nuclear compaction. Although not structurally related to chicken RI histone H5, which is required for erythrocyte maturation, H1-2 may constitute its functional counterpart. Our findings may offer evolutionary insights into the function of H1 variants.

Key words: replication-dependent histone, replication-independent histone, evolution, medaka

*Corresponding author e-mail: toru@waseda.jp

 
Retinoic acid metabolizing factor xCyp26c is specifically expressed in neuroectoderm and regulates anterior neural patterning in Xenopus laevis
Misaki Tanibe 1,  Tatsuo Michiue* 1,2,  Akira Yukita 1,  Hiroki Danno 1,  Masayuki Ikuzawa 2,  Shoichi Ishiura 1  and Makoto Asashima* 1,2,3.
Int. J. Dev. Biol. (2008) 52: 893-901 

1: Graduate School of Arts and Sciences, The University of Tokyo. 2: Organ Development Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST). 3: Organ Regeneration project, International Cooperative Research Program (ICORP), Japan Science and Technology Agency (JST), Japan

ABSTRACT: Anterior-posterior neural patterning is determined during gastrulation when head structure is induced. Induction of anterior neural structures requires inhibition of Wnt signaling by several Wnt antagonists. We performed microarray analysis to isolate genes regulated by canonical Wnt signaling and abundantly expressed in the anterior neuroectoderm at the early neurula stage. We identified xCyp26c, a Cyp26 (RA-metabolizing protein)-family gene. In situ hybridization showed xCyp26c expression restricted to the anterior region of neurula, while xCyp26a was expressed in both anterior and posterior regions. At the tadpole stage, xCyp26c was also expressed in restricted sets of cranial nerves. Microarray, RT-PCR and in situ hybridization analyses revealed decreased xCyp26c expression with overexpression of b-catenin, suggesting regulation by Wnt/b-catenin signaling. We also assessed the effects of retinoic acid (RA) on xCyp26c expression. Embryos treated with 10-7 M RA showed an anterior shift in the spatial expression of xCyp26c, reflecting a posteriorization effect. Conversely, expression patterns in embryos treated with more than 10-6 M RA were less affected and remained restricted to the most anterior region. Moreover, injection of xCyp26c mRNA into animal poles caused head defects, and exogenous expression of xCyp26c rescued the posteriorizing effect of RA treatment. Taken together, these results implicated a role for xCyp26c in anterior patterning via RA signaling.

Key words: Xenopus, retinoic acid, Wnt signaling, AP neural patterning, rhombencephalon

*Corresponding author e-mail: asashi@bio.c.u-tokyo.ac.jp 

 
Defective calcium release during in vitro fertilization of maturing oocytes of LT/Sv mice
Karolina Archacka 1,2,  Anna Ajduk2,  Pawel Pomorski 3,  Katarzyna Szczepanska 2,  Marek Maleszewski 2  and Maria A. Ciemerych 1,2*
Int. J. Dev. Biol. (2008) 52: 903-912

1: Department of Cytology and  2: Department of Embryology, Institute of Zoology, Faculty of Biology, University of Warsaw and  3: Department of Cell Biology, The Nencki Institute of Experimental Biology, Warsaw, Poland

ABSTRACT: Oocytes of LT/Sv mice have anomalous cytoplasmic and nuclear maturation. Here, we show that in contrast to the oocytes of wild-type mice, a significant fraction of LT/Sv oocytes remains arrested at the metaphase of the first meiotic division and is unable to undergo sperm-induced activation when fertilized 15 hours after the resumption of meiosis. We also show that LT/Sv oocytes experimentally induced to resume meiosis and to reach metaphase II are unable to undergo activation in response to sperm penetration. However, the ability for sperm-induced activation developed during prolonged in vitro culture. Both types of LT/Sv oocytes, i.e. metaphase I and those that were experimentally induced to reach metaphase II, underwent activation when they were fertilized 21 hours after germinal vesicle breakdown (GVBD). Thus, the ability of LT/Sv oocytes to become activated by sperm depends on cytoplasmic maturation rather than on nuclear maturation i.e. on the progression of meiotic division. We also show that sperm penetration induces fewer Ca2+ transients in LT/Sv oocytes than in control wild-type oocytes. In addition, we found that the levels of mRNA encoding different isoforms of protein kinase C (alpha, delta and zeta), that are involved in meiotic maturation and signal transduction during fertilization, differed between metaphase I LT/Sv oocytes which cannot be activated by sperm, and those which are able to undergo activation after fertilization. However, no significant differences between these oocytes were found at the level of mRNA encoding IP3 receptors which participate in calcium release during oocyte fertilization.

Key words: LT/Sv, meiosis, in vitro fertilization, activation, calcium oscillations

*Corresponding author e-mail: ciemerych@biol.uw.edu.pl

 
Maternal RNAs encoding transcription factors for germline-specific gene expression in Drosophila embryos
Jun Yatsu 1,2,  Makoto Hayashi 1,2,  Masanori Mukai 3,  Kayo Arita 4,  Shuji Shigenobu 1,5  and Satoru Kobayashi 1,2*
Int. J. Dev. Biol. (2008) 52: 913-923

1: Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Higashiyama, Myodaiji, Okazaki.  2: Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Myodaiji, Okazaki.  3: Department of Biology, Faculty of Science and Engineering, Konan University, Kobe.  4: Clinical Research Center for Blood Diseases, National Hospital Organization Nagoya Medical Center, Nagoya and  5: Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan

ABSTRACT: In early Drosophila embryos, germ plasm is localized to the posterior pole region and is partitioned into the germline progenitors, known as pole cells. Germ plasm contains the maternal factors required for germline development. It has been proposed that germline-specific gene expression is initiated by the function of maternal factors that are enriched in the germ plasm. However, such factors have remained elusive. Here, we describe a genome-wide survey of maternal transcripts that encode for transcription factors and are enriched in the germ plasm. We isolated pole cells from blastodermal embryos by fluorescence-activated cell sorting (FACS) and then used these isolated cells in a microarray analysis. Among the 835 genes in the Gene Ontology (GO) category “transcription regulator activity” listed in FlyBase, 68 were found to be predominantly expressed in pole cells as compared to whole embryos. As the early pole cells are known to be transcriptionally quiescent, the listed transcripts are predicted to be maternal in origin. Our in situ hybridization analysis revealed that 27 of the 68 transcripts were enriched in the germ plasm. Among the 27 transcripts, six were found to be required for germline-specific gene expression of vasa and/or nanos by knockdown experiments using RNA interference (RNAi). The identified transcripts encode a transcriptional activator (ovo), components of the transcriptional initiation complexes (Trf2, bip2 and Tif-IA), and the Ccr4-Not complex (CG31716 and l(2)NC136). Our study demonstrates that germ plasm contains maternal transcripts encoding transcriptional regulators for germline-specific gene expression in pole cells.

Key words: germ line, germ plasm, pole cell, transcription factor, Drosophila

*Corresponding author e-mail: skob@nibb.ac.jp

Integrins contribute to the establishment and maintenance of cell polarity in the follicular epithelium of the Drosophila ovary
Ana Fernández-Miñán, Laura Cobreros, Acaimo González-Reyes and María D. Martín-Bermudo*
Int. J. Dev. Biol. (2008) 52: 925-932

Centro Andaluz de Biología del Desarrollo, CSIC-Univ. Pablo de Olavide, Sevilla, Spain

ABSTRACT: The generation of epithelial cell polarity is a key process during development. Although the induction and orientation of cell polarity by cell-cell and cell-extracellular matrix (ECM) interactions is well established, the molecular mechanisms by which signals from the ECM control cell polarity in developing epithelial tissues remain poorly understood. Here, we have used the follicular epithelium of the Drosophila ovary to investigate the role that integrins, the main cell-ECM receptors, play in the establishment of apicobasal polarity. Mature follicle cells have an apical side facing the germ line and a basal side in contact with a basement membrane. Our results show that integrins - presumably via interactions with the basement membrane - play a reinforcing role in follicle cell polarization, as they are required to establish and/or maintain follicle cell membrane asymmetry only when contact with the germ line is prevented. We suggest that the primary cue for polarization of the follicular epithelium is contact with the germline cells. In addition, while interfering with apical and lateral polarization cues leads to apoptosis, we show here that inhibition of contact with the basement membrane mediated by integrins does not affect cell survival. Finally, we provide evidence to suggest that integrins are required to orientate epithelial polarity in vivo.

Key words: integrin, apicobasal polarity, basement membrane, epithelial polarity

*Corresponding author e-mail: mdmarber@upo.es

The serpin Spn5 is essential for wing expansion in Drosophila melanogaster
Yves Charron 1,  Rime Madani 1,  Chantal Combepine 1, Vincent Gajdosik 2,  Yeukuang Hwu 3, Giorgio Margaritondo 2  and Jean-Dominique Vassalli 1*
Int. J. Dev. Biol. (2008) 52: 933-942 

1: Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Switzerland.  2: School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.  3: Institute of Physics, Academica Sinica, Nankang, Taiwan, ROC.

ABSTRACT: Serpins, a superfamily of protease inhibitors, control proteolytic cascades in many physiological processes. Genomic studies have revealed the presence of a high number of serpin-encoding genes in Drosophila melanogaster, but their functions remain largely unknown. In a biochemical screen designed to detect protease inhibitors that may be implicated in early Drosophila development, we identified in embryos a ligand that forms a 67 kDa SDS-stable complex with the broad spectrum protease trypsin. Characterization of this ligand revealed it to be the recently described serpin, Spn5. Expression analysis by in situ and Northern blot hybridization indicated maternal transmission of the transcript as well as zygotic expression in many larval, pupal and adult tissues. Targeted repression by RNA interference did not alter early embryogenesis but resulted in a complete defect in the unfolding and expansion of the wings of freshly eclosed mutant flies, without other detectable effects on development.

Key words: Spn5, serpin, Drosophila, embryo, wing expansion

*Corresponding author e-mail: Jean-Dominique.Vassalli@medecine.unige.ch

Two msh/msx-related genes, Djmsh1 and Djmsh2, contribute to the early blastema growth during planarian head regeneration
Linda Mannini 1, Paolo Deri 1, Vittorio Gremigni 2,  Leonardo Rossi 2,  Alessandra Salvetti 2  and Renata Batistoni 1*
Int. J. Dev. Biol. (2008) 52: 943-952 

1: Dipartimento di Biologia  and  2: Dipartimento di Morfologia Umana e Biologia Applicata, Università di Pisa, Italy

ABSTRACT: Regeneration in planarians is an intriguing phenomenon, based on the presence of pluripotent stem cells, known as neoblasts. Following amputation, these cells activate mitotic divisions, migrate distally and undergo differentiation, giving rise to the regeneration blastema. We have identified two msh/msx-related genes, Djmsh1 and Djmsh2, which are expressed in distinct cell populations of the planarian Dugesia japonica and activated, with different patterns, during head regeneration. We demonstrate that RNA interference of Djmsh1 or Djmsh2 generates a delay in the growth of cephalic blastema, interfering with the dynamics of mitoses during its initial formation. Our data also reveal that the activity of the two planarian msh genes is required to regulate Djbmp expression during head regeneration. This study identifies, for the first time, a functional association between muscle segment homeobox (MSH) homeoproteins and BMP signaling during stem cell-based regeneration of the planarian head and provides a functional analysis of how msh genes may regulate in vivo the regenerative response of planarian stem cells.

Key words: planarian, regeneration, msh/msx, RNAi, bmp

*Corresponding author e-mail: rbatistoni@biologia.unipi.it

 
Alteration of the shoot radial pattern in Arabidopsis thaliana by a gain-of-function allele of the class III HD-Zip gene INCURVATA4
Isabel Ochando 1,  Santiago González-Reig, Juan-José Ripoll 2,  Antonio Vera and Antonio Martínez-Laborda*
Int. J. Dev. Biol. (2008) 52: 953-961 

Area de Genética, Universidad Miguel Hernández, Campus de Sant Joan d’Alacant, E-03550 Alicante, Spain

ABSTRACT: Class III HD-Zip (HD-Zip III) family genes play key roles in a number of fundamental developmental programs in Arabidopsis thaliana, such as embryo patterning, meristem initiation and homeostasis, lateral organ polarity and vascular development. Semidominant gain-of-function alleles of the HD-Zip III genes PHABULOSA (PHB), PHAVOLUTA (PHV) and REVOLUTA (REV) disrupt the negative regulation of these genes by a mechanism of microRNA interference. We provide evidence that the gain-of-function icu4-1 allele of INCURVATA4, a gene encoding the HD-Zip III transcription factor ATHB15/CORONA (CNA), stimulates the production of vascular tissues, supporting a role for ICU4 in promoting vascular development. Occasionally, homozygous mutants for this allele show a reduced number of thick shoot vascular bundles, although normal collateral polarity remains unchanged. Genetic analysis of icu4-1 and phb-1D, a gain-of-function allele of the related PHB gene, revealed antagonism in lateral organ polarity between both mutations and a synergistic interaction in shoots, with transformation of the polarized collateral bundles into a radialized amphivasal pattern. These results indicate that the precise regulation of HD-Zip III genes confers positional information which is required to establish the number and pattern of vascular bundles in the stem. In addition, we present results that suggest an interaction between ICU4 function and auxin signaling.

Key words: Arabidopsis, class III HD-Zip gene, shoot radial pattern, vascular development

*Corresponding author e-mail: laborda@umh.es

 
Short Communications

The embryonic cell lineage of the nematode Rhabditophanes sp.
Wouter Houthoofd, Maxime Willems, Kim Jacobsen, August Coomans and Gaetan Borgonie*
Int. J. Dev. Biol. (2008) 52: 963-967

Department of Biology, Ghent University, Ghent, Belgium

ABSTRACT: One of the unique features of the model organism Caenorhabditis elegans is its invariant development, where a stereotyped cell lineage generates a fixed number of cells with a fixed cell type. It remains unclear how embryonic development evolved within the nematodes to give rise to the complex, invariant cell lineage of C. elegans. Therefore, we determined the embryonic cell lineage of the nematode, Rhabditophanes sp. (family Alloionematidae) and made detailed cell-by-cell comparison with the known cell lineages of C. elegans, Pellioditis marina and Halicephalobus gingivalis. This gave us a unique data set of four embryonic cell lineages, which allowed a detailed comparison between these cell lineages at the level of each individual cell. This lineage comparison revealed a similar complex polyclonal fate distribution in all four nematode species (85% of the cells have the same fate). It is striking that there is a conservation of a ‘C. elegans’ like polyclonal cell lineage with strong left-right asymmetry. We propose that an early symmetry-breaking event in nematodes of clade IV-V is a major developmental constraint which shapes their asymmetric cell lineage.

Key words: 4D microscopy, cell lineage, embryo, evolution, nematode, Rhabditophanes sp

*Corresponding author e-mail: gaetan.borgonie@ugent.be

Evolution of CUT class homeobox genes: insights from the genome of the amphioxus, Branchiostoma floridae
Naohito Takatori and Hidetoshi Saiga*
Int. J. Dev. Biol. (2008) 52: 969-977 

Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachiohji, Japan

ABSTRACT: CUT class homeobox genes, including CUX/CASP, ONECUT, SATB and COMPASS family genes, are known to exhibit diverse features in the homeodomain and the domain architecture. Furthermore, the intron/exon organization of CUX/CASP is different between vertebrates and protostomes, and SATB genes are only known for vertebrates, whereas COMPASS genes have only been found in protostomes. These observations suggest a complex evolutionary history for the CUT class homeobox genes, but the evolution of CUT class homeobox genes in the lineage to vertebrates remained largely unknown. To obtain clearer insights into this issue, we searched the genome of amphioxus, Branchiostoma floridae, a lower chordate, for CUT class homeobox genes by extensive BLAST survey and phylogenetic analyses. We found that the genome of Branchiostoma floridae encodes each single orthologue of CUX/CASP, ONECUT, and COMPASS, but not the SATB gene, and one atypical CUT gene likely specific to this species. In addition, the genomic structure of the amphioxus CUX/CASP gene turned out to be protostome-type, but not vertebrate-type. Based on these observations, we propose a model in which SATB is suggested to evolve at the expense of COMPASS and this change, together with the structural change in CUX/CASP, is supposed to take place in the lineage to vertebrates after divergence of the amphioxus and vertebrate ancestors. The present study provides an example of dramatic evolution among homeobox gene groups in the vertebrate lineage and highlights the ancient character of amphioxus, retaining genomic features shared by protostomes.

Key words: Cux, COMPASS, Onecut, SATB, chordate

*Corresponding author e-mail: saiga-hidetoshi@tmu.ac.jp

Characterization of fibroblast-like cells from the rat olfactory bulb
Masoud Soleimani* 1,  Samad Nadri* 2,3,  Mohammad Salehi 2,4,  Aligholi Sobhani 4,  and Athena Hajarizadeh 5.
Int. J. Dev. Biol. (2008) 52: 979-984

1: Hematology Department, Faculty of Medical Science, Tarbiat Modares University,  2: Stem Cells and Tissue Engineering Department, Stem Cell Technology Institute,  3: Biomedical Engineering and Medical Physics Department, Faculty of Medicine, Shahid Beheshti University of Medical Science,  4: Anatomy Department, Faculty of Medicine, Tehran University of Medical Science and  5: Molecular Biology Department, Stem Cell Technology Institute, Tehran, Iran

ABSTRACT: The isolation and characterization of stem cells from an alternative tissue is a subject of intensive investigation. In the present study, we have focused on the characterization of fibroblastic cells in olfactory bulb tissue of the rat. To this end, 4-6 week old rats were killed and their olfactory bulb tissue was dissected out. Olfactory bulb derived fibroblast-like cells were recovered by adhesion to cell culture plastic. The plastic adherent cultivated cells were induced to differentiate along osteoblastic, adipogenic and chondrogenic lineages. Furthermore, the expression of some surface antigens was investigated. We obtained purified cells with spindle shaped morphology in primary culture, which differentiated into mesenchymal lineages. These cells expressed CD29 and CD90 (Thy1.1) surface antigens, but not CD31, CD34 and CD45. Our results indicate that fibroblast-like cells from the olfactory bulb are mesenchymal stem cells in nature. Taken together, our data suggest that olfactory bulb tissue may constitute a new source of mesenchymal stem cells and could be used for the treatment of injury.

Key words: fibroblast-like cell, mesenchymal stem cell, surface antigen, differentiation potential

*Corresponding author e-mail: Soleim_m@modares.ac.ir; s.nadri@stemcellstech.com

Developmental Expression Patterns

Isolation and expression analysis of foxj1 and foxj1.2 in zebrafish embryos
Emil Aamar and Igor B. Dawid*
Int. J. Dev. Biol. (2008) 52: 985-991 

Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD, USA

ABSTRACT: In this report, we present the isolation and identification of a zebrafish homolog of the winged helix\forkhead transcription factor Foxj1. Foxj1 was identified in other species but not in zebrafish. Foxj1 was shown in mice to be required in ciliogenesis and left-right asymmetry establishment. Here we present a spatio-temporal expression pattern of zebrafish foxj1, showing that this gene is expressed in dorsal forerunner cells, Kupffer’s vesicle, the floor plate, pronephric ducts and kidney. This expression pattern is overlapping but different from that of the foxj1.2, the closest related gene in zebrafish. Foxj1 in zebrafish appears to have similar functions as those reported in other species connected to ciliogenesis and left-right asymmetry.

Key words: Foxj1, Foxj1.2, dorsal forerunner cell, Kupffer’s vesicle, floor plate, pronephric duct

*Corresponding author e-mail: idawid@nih.gov

Identification and gene expression of versican during early development of Xenopus
Paola Casini 1,  Michela Ori* 1,  Angela Avenoso 2,  Angela D’Ascola 2,  Paola Traina 2,  Walter Mattina 2,  Roberto Perris 3, Giuseppe M. Campo 2,  Alberto Calatroni 2,  Irma Nardi 1  and Salvatore Campo 2.
Int. J. Dev. Biol. (2008) 52: 993-918

1: Unit of Cellular and Developmental Biology, Dept. of Biology, University of Pisa, Pisa,  2: Dept. of Biochemical, Physiological and Nutritional Sciences, School of Medicine, University of Messina, Policlinico Universitario, Torre Biologica, Messina and  3. Lab. of Tumour Biology and Stem Cells, Dept. of Genetics, Microbiology and Anthropology, University of Parma, Parma, Italy.

ABSTRACT: The chondroitin sulfate proteoglycan (PG) PG-M/versican is known to be a primary component of the vertebrate embryonic extracellular matrix and, in the mouse, functional abrogation of the versican gene leads to severe cardiovascular malformations and embryonic lethality. In order to provide a means for approaching the study of the role of versican during embryogenesis, we have cloned the Xenopus versican cDNA and we have performed in situ hybridization on embryos at different stages of development. We showed maternal Xversican transcription, as well as a previously undocumented early expression of the PG during gastrulation and neurulation. At later stages of development, spatial transcription of Xversican correlates with the patterns of migrating neural crest cells (NCC) and it is expressed in embryonic regions representing the final sites of arrest of NCC. Xversican mRNA was also detected in a subpopulation of trunk NCC migrating into the fin, in tissues flanking the trunk NCC ventral migratory pathway and in post-migratory cranial skeletogenic NCC. Further embryonic sites expressing Xversican were the pronephros, pronephric ducts, heart anlage and branchial pouches. These findings constitute the basis for future studies aimed at clarifying unresolved aspects of versican function during embryogenesis.

Key words: chondroitin sulfate proteoglycan, versican, embryo, neural crest, Xenopus laevis

*Corresponding author e-mail: mori@biologia.unipi.it

 
Cloning and developmental expression of the soxB2 genes, sox14 and sox21, during Xenopus laevis embryogenesis
Doreen D. Cunningham, Zhuo Meng, Bernd Fritzsch and Elena Silva Casey*
Int. J. Dev. Biol. (2008) 52: 999-1004 

Georgetown University, Department of Biology, Washington DC and 1 Creighton University, Department of Biomedical Sciences, Omaha, NE, USA

ABSTRACT: The Sox family of transcription factors is thought to regulate gene expression in a wide variety of developmental processes. Here we describe the cloning of the X. laevis orthologs of the SoxB2 family of transcription factors, sox14 and sox21. In situ hybridization revealed that sox14 expression is restricted to the hypothalamus, dorsal thalamus, the optic tectum, a region of the somatic motornucleus in the midbrain and hindbrain, the vestibular nuclei in the hindbrain and a discrete ventral domain in the developing spinal cord. In contrast to the limited expression domain of sox14, sox21 is found throughout the developing central nervous system, including the olfactory placodes, with strongest expression at the boundary between the midbrain and hindbrain.

Key words: Sox, neurogenesis, Xenopus, neural tube

*Corresponding author e-mail: emc26@georgetown.edu

Spatiotemporal expression of the selenoprotein P genein postimplantational mouse embryos
Se-Ra Lee 1,  Jung-Min Yon 1,  In-Jeoung Baek 1, Mi-Ra Kim 1, Chun-Gui Park 2,  Beom-Jun Lee 1,  Young-Won Yun 1  and Sang-Yoon Nam* 1.
Int. J. Dev. Biol. (2008) 52: 1005-1011

1: College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University, Cheongju, Korea  and  2: Samkwang-Bio. Inc., Kumsan, Chungnam, Korea

ABSTRACT Selenoprotein P (Sepp) is an extracellular glycoprotein which functions principally as a selenium (Se) transporter and antioxidant. In order to assess the spatiotemporal expression of the Sepp gene during mouse embryogenesis, quantitative RT-PCR and in situ hybridization analyses were conducted in embryos and extraembryonic tissues, including placenta. Sepp mRNA expression was detected in all embryos and extraembryonic tissues on embryonic days (E) 7.5 to 18.5. Sepp mRNA levels were high in extraembryonic tissues, as compared to embryos, on E 7.5-13.5. However, the levels were higher in embryos than in extraembryonic tissues on E 14.5-15.5, but were similar in both tissues during the subsequent periods prior to birth. According to the results of in situ hybridization, Sepp mRNA was expressed principally in the ectoplacental cone and neural ectoderm, including the neural tubes and neural folds. In whole embryos, Sepp mRNA was expressed abundantly in nervous tissues on E 9.5-12.5. Sepp mRNA was also expressed in forelimb and hindlimb buds on E 10.5-12.5. In the sectioned embryos, on E 13.5-18.5, Sepp mRNA was expressed persistently in the developing limbs, gastrointestinal tract, nervous tissue, lung, kidney and liver. On E 16.5-18.5, Sepp mRNA expression in the submandibular gland, whisker follicles, pancreas, urinary bladder and skin was apparent. In particular, Sepp mRNA was detected abundantly in blood cells during all the observed developmental periods. These results show that Sepp may function as a transporter of selenium, as well as an antioxidant, during embryogenesis.

Key words: selenoprotein P, quantitative RT-PCR, in situ hybridization, mouse embryo

*Corresponding author e-mail: synam@cbu.ac.kr