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Gbb/BMP signaling is required to maintain energy homeostasis in Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The coordination of animal growth and development requires adequate nutrients. During times of insufficient food, developmental progression is slowed and stored energy is utilized to ensure that cell and tissue survival are maintained. Here, we report our finding that the Gbb/BMP signaling pathway known to play an important role in many developmental processes in both vertebrates and invertebrates, is critical in the Drosophila larval fat body for regulating energy homeostasis. Animals with mutations in the Drosophila BMP-5,7 orthologue, glass bottom boat (gbb), or in its signaling components, display phenotypes simila...
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Ballard SL, Jarolimova J, Wharton KA Tags: Dev Biol Source Type: journals

Foxj3 transcriptionally activates Mef2c and regulates adult skeletal muscle fiber type identity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The mechanisms that regulate skeletal muscle differentiation, fiber type diversity and muscle regeneration are incompletely defined. Forkhead transcription factors are critical regulators of cellular fate determination, proliferation, and differentiation. We identified a forkhead/winged helix transcription factor, Foxj3, which was expressed in embryonic and adult skeletal muscle. To define the functional role of Foxj3, we examined Foxj3 mutant mice. Foxj3 mutant mice are viable, but have significantly fewer Type I slow-twitch myofibers and have impaired skeletal muscle contractile function compared to their wild type c...
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Alexander MS, Shi X, Voelker KA, Grange RW, Garcia JA, Hammer RE, Garry DJ Tags: Dev Biol Source Type: journals

Cv2, Functioning as a Pro-BMP Factor via Twisted Gastrulation, is Required for Early Development of Nephron Precursors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this report, we show that the augmentation of BMP signaling by a BMP-binding secreted factor, Crossveinless2 (Cv2), is essential for the early embryonic development of mammalian nephrons. In the Cv2-null mouse, the number of cap condensates (clusters of nephron progenitors, which normally express Cv2) was decreased, and the condensate cells exhibited a reduced level of aggregation. In these Cv2(-/-) condensates, the level of phosphorylated Smad1 (pSmad1) was substantially lowered. The loss of a Bmp7 allele in the Cv2(-/-) mouse enhanced the cap condensate defects and further decreased the level of pSmad1 in this tissue....
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Ikeya M, Fukushima K, Kawada M, Onishi S, Furuta Y, Yonemura S, Kitamura T, Nosaka T, Sasai Y Tags: Dev Biol Source Type: journals

Cell cycle independent role of Cyclin E during neural cell fate specification in Drosophila is mediated by its regulation of Prospero function.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During development, neural progenitor cells or neuroblasts generate a great intra-and inter-segmental diversity of neuronal and glial cell types in the nervous system. In thoracic segments of the embryonic central nervous system of Drosophila, the neuroblast NB6-4t undergoes an asymmetric first division to generate a neuronal and a glial sublineage, while abdominal NB6-4a divides once symmetrically to generate only 2 glial cells. We had earlier reported a critical function for the G1 cyclin, CyclinE (CycE) in regulating asymmetric cell division in NB6-4t. Here we show that (i) this function of CycE is independent of it...
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Berger C, Kannan R, Myneni S, Renner S, Shashidhara LS, Technau GM Tags: Dev Biol Source Type: journals

The contribution of Notch1 to nephron segmentation in the developing kidney is revealed in a sensitized Notch2 background and can be augmented by reducing Mint dosage.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We previously determined that Notch2, and not Notch1 was required for forming proximal nephron segments. The dominance of Notch2 may be conserved in humans, since Notch2 mutations occur in Alagille syndrome (ALGS) 2 patients, which includes renal complications. To test whether mutations in Notch1 could increase the severity of renal complications in ALGS, we inactivated conditional Notch1 and Notch2 alleles in mice using a Six2-GFP::Cre. This BAC transgene is expressed mosaically in renal epithelial progenitors but uniformly in cells exiting the progenitor pool to undergo mesenchymal to epithelial transition. Although ...
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Surendran K, Boyle S, Barak H, Kim M, Stromberski C, McCright B, Kopan R Tags: Dev Biol Source Type: journals

Cell migration during morphogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19914236 [PubMed - as supplied by publisher] (Source: Developmental Biology)
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Aman A, Piotrowski T Tags: Dev Biol Source Type: journals

Retinoic acid signaling targets Hox genes during the amphioxus gastrula stage: insights into early anterior-posterior patterning of the chordate body plan.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Previous developmental studies of vertebrate development have shown that retinoic acid (RA) signaling at the gastrula stage strongly influences anterior-posterior (A-P) patterning of the neurula and later stages. However, much less is known about the more immediate effects of RA signaling on gene transcription and developmental patterning at the gastrula stage. To investigate the targets of RA signaling during the gastrula stage, we used the basal chordate amphioxus, in which gastrulation involves very minimal tissue movements. First, we determined the effect of altered RA signaling on expression of 42 genes (encoding ...
Source: Developmental Biology - November 12, 2009 Category: Biology Authors: Koop D, Holland ND, Sémon M, Alvarez S, Rodriguez de Lera A, Laudet V, Holland LZ, Schubert M Tags: Dev Biol Source Type: journals

Mob as Tumor Suppressor is Activated at the Cell Membrane to Control Tissue Growth and Organ Size in Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Growth-inhibition mediated by Hippo (Hpo) signaling is essential for tissue growth and organ size control in Drosophila. However, the cellular mechanism by which the core components like Mob as tumor suppressor (Mats) and Warts (Wts) protein kinase are activated is poorly understood. In this work, we found that the endogenous Mats is located at the plasma membrane in developing tissues. Membrane-targeting constitutively activates Mats to promote apoptosis and reduce cell proliferation, which leads to reduced tissue growth and organ size. Moreover, the ability of membrane-targeted Mats to inhibit tissue growth required ...
Source: Developmental Biology - November 11, 2009 Category: Biology Authors: Ho LL, Wei X, Shimizu T, Lai ZC Tags: Dev Biol Source Type: journals

Formation of the insect head involves lateral contribution of the intercalary segment, which depends on Tc-labial function.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The insect head is composed of several segments. During embryonic development the segments fuse to form a rigid head capsule where obvious segmental boundaries are lacking. Hence, the assignment of regions of the insect head to specific segments is hampered, especially with respect to dorsal (vertex) and lateral (gena) parts. We show that upon Tribolium labial (Tc-lab) knock down the intercalary segment is deleted but not transformed. Further, we find that the intercalary segment contributes to lateral parts of the head cuticle in Tribolium. Based on several additional mutant and RNAi phenotypes that interfere with gna...
Source: Developmental Biology - November 11, 2009 Category: Biology Authors: Posnien N, Bucher G Tags: Dev Biol Source Type: journals

Requirement for Lmo4 in the Vestibular Morphogenesis of Mouse Inner Ear.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During development, compartmentalization of an early embryonic structure produces blocks of cells with distinct properties and developmental potentials. The auditory and vestibular components of vertebrate inner ears are derived from defined compartments within the otocyst during embryogenesis. The vestibular apparatus, including three semicircular canals, saccule, utricle, and their associated sensory organs, detects angular and linear acceleration of the head and relays the information through vestibular neurons to vestibular nuclei in the brainstem. How the early developmental events manifest vestibular structures a...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Deng M, Pan L, Xie X, Gan L Tags: Dev Biol Source Type: journals

Pax2 and Pea3 synergize to activate a novel regulatory enhancer for spalt4 in the developing ear.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transcription factor spalt4 is a key early-response gene in otic placode induction. Here, we characterize the cis-regulatory regions of spalt4 responsible for activation of its expression in the developing otic placode and report the isolation of a novel core enhancer. Identification and mutational analysis of putative transcription factor binding sites reveal that Pea3, a downstream effector of FGF signaling, and Pax2 directly activate spalt4 during ear development. Morpholino-mediated knock-down of each factor reduces or eliminates reporter expression. In contrast, combined over-expression of Pea3 and Pax2 drives...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Barembaum M, Bronner-Fraser M Tags: Dev Biol Source Type: journals

Role of Epiprofin, a zinc-finger transcription factor, in limb development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The formation and maintenance of the apical ectodermal ridge (AER) is critical for the outgrowth and patterning of the vertebrate limb. In the present work, we have investigated the role of Epiprofin (Epfn/Sp6), a member of the SP/KLF transcription factor family that is expressed in the limb ectoderm and the AER, during limb development. Epfn mutant mice have a defective autopod that shows mesoaxial syndactyly in the forelimb and synostosis (bony fusion) in the hindlimb and partial bidorsal digital tips. Epfn mutants also show a defect in the maturation of the AER that appears flat and broad, with a double ridge phenot...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Talamillo A, Delgado I, Nakamura T, de-Vega S, Yoshitomi Y, Unda F, Birchmeier W, Yamada Y, Ros MA Tags: Dev Biol Source Type: journals

Foregut separation and tracheo-oesophageal malformations: The role of tracheal outgrowth, dorso-ventral patterning and programmed cell death.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Foregut division - the separation of dorsal (oesophageal) from ventral (tracheal) foregut components - is a crucial event in gastro-respiratory development, and frequently disturbed in clinical birth defects. Here, we examined three outstanding questions of foregut morphogenesis. The origin of the trachea is suggested to result either from respiratory outgrowth or progressive septation of the foregut tube. We found normal foregut lengthening despite failure of tracheo-oesophageal separation in Adriamycin-treated embryos, whereas active septation was observed only in normal foregut morphogenesis, indicating a primary ro...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Ioannides AS, Massa V, Ferraro E, Cecconi F, Spitz L, Henderson DJ, Copp AJ Tags: Dev Biol Source Type: journals

BMP signaling coordinates gene expression and cell migration during precardiac mesoderm development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Gene regulatory networks control the progressive specification of cell types and govern morphogenetic events during development. However, how morphogenetic events reciprocally affect gene expression remains poorly understood. Here, we analyzed the function of BMP signaling and expression of downstream target genes during cell migration of the precardiac mesoderm (trunk ventral cells, TVCs) in ascidian embryos. Our results indicate that migrating TVCs experience increasing BMP signaling as they migrate towards the ventral trunk epidermis, which expresses sustained levels of Bmp2/4. This increasing signaling intensity al...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Christiaen L, Stolfi A, Levine M Tags: Dev Biol Source Type: journals

BMP antagonists and FGF signaling contribute to different domains of the neural plate in Xenopus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In ectodermal explants from Xenopus embryos, inhibition of BMP signaling is sufficient for neural induction, leading to the idea that neural fate is the default state in the ectoderm. Many of these experiments assayed the action of BMP antagonists on animal caps, which are relatively naïve explants of prospective ectoderm, and different results have led to debate regarding both the mechanism of neural induction and the appropriateness of animal caps as an assay system. Here we address whether BMP antagonists are only able to induce neural fates in pre-patterned explants, and the extent to which neural induction re...
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Wills AE, Choi VM, Bennett MJ, Khokha MK, Harland RM Tags: Dev Biol Source Type: journals

Which FGF ligands are involved in lens induction?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19913010 [PubMed - as supplied by publisher] (Source: Developmental Biology)
Source: Developmental Biology - November 10, 2009 Category: Biology Authors: Smith AN, Radice G, Lang RA Tags: Dev Biol Source Type: journals

A new role for the SHATTERPROOF genes during Arabidopsis gynoecium development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Gynoecium development is a complex process which is regulated by key factors that control the spatial formation of the apical, medial and basal parts. SHATTERPROOF1 (SHP1) and SHP2, two closely related MADS-box genes, redundantly control the differentiation of the dehiscence zone and promote the lignification of adjacent cells. Furthermore, SHP1 and SHP2 have shown to play an important role in ovule identity determination. The present work identifies a new function for these two genes in promoting stigma, style and medial tissue development. This new role was discovered by combining the shp1 shp2 double mutant with the...
Source: Developmental Biology - November 6, 2009 Category: Biology Authors: Colombo M, Brambilla V, Marcheselli R, Caporali E, Kater MM, Colombo L Tags: Dev Biol Source Type: journals

A role of the LIM-homeobox gene Lhx2 in the regulation of pituitary development.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we show that the LIM-homeobox gene Lhx2 is extensively expressed in the developing ventral diencephalon, including the infundibulum and the posterior lobe of the pituitary. Deletion of Lhx2 gene results in persistent cell proliferation, a complete failure of evagination of the neuroectoderm in the ventral diencephalon, and defects in the formation of the distinct morphological features of the infundibulum and the posterior pituitary lobe. Rathke's pouch is formed and endocrine cell lineages are generated in the anterior/intermediate pituitary lobes of the Lhx2 mutant. However, the shape and organization of t...
Source: Developmental Biology - November 6, 2009 Category: Biology Authors: Zhao Y, Mailloux CM, Hermesz E, Palkovits M, Westphal H Tags: Dev Biol Source Type: journals

Hippo signaling regulates Yorkie nuclear localization and activity through 14-3-3 dependent and independent mechanisms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Hippo (Hpo) signaling pathway controls cell growth, proliferation and apoptosis in both Drosophila and vertebrates. In Drosophila, Hpo signaling regulates gene expression by inhibiting a transcription complex consisting of the transcriptional coactivator Yorkie (Yki) and the TEAD/TEF family of transcription factor Scalloped (Sd). Here we provide genetic evidence that both isoforms of 14-3-3, 14-3-3varepsilon and 14-3-3zeta, regulate Yki activity through modulating its subcellular localization. Inactivation of 14-3-3 by RNAi or genetic mutations enhanced whereas overexpression of 14-3-3 suppressed tissue overgrowth ...
Source: Developmental Biology - November 6, 2009 Category: Biology Authors: Ren F, Zhang L, Jiang J Tags: Dev Biol Source Type: journals

Distinct contributions from the hindbrain and mesenchyme to inner ear morphogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A mature inner ear is a complex structure consisting of vestibular and auditory components. Microsurgical ablations, rotations and translocations were performed in ovo to identify the tissues that control inner ear morphogenesis. We show that mesenchyme/ectoderm adjacent to the developing ear specifically governs the shape of vestibular components - the semicircular canals and ampullae - by conferring anteroposterior axial information to these structures. In contrast, removal of individual hindbrain rhombomeres adjacent to the developing ear preferentially affects the growth and morphogenesis of the auditory subdivisio...
Source: Developmental Biology - November 5, 2009 Category: Biology Authors: Liang JK, Bok J, Wu DK Tags: Dev Biol Source Type: journals

The role of eyg Pax gene in the development of the head vertex in Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Drosophila head vertex is composed of three ocelli, stereotypic bristle patterns and characteristic cuticles. It is derived from the fusion of two eye-antenna discs. The head vertex primordium is located at the anterior-dorsal region of the eye disc. The orthodenticle (otd) homeobox gene is expressed in the primordium and is functionally required for its development and patterning. Here we show that the Pax gene eye gone (eyg) is expressed adjacent to the otd expression domain in the eye disc. otd is required and sufficient to repress eyg transcription, thereby preventing eyg from expressing in the head vertex prim...
Source: Developmental Biology - November 5, 2009 Category: Biology Authors: Wang LH, Huang YT, Tsai YC, Sun YH Tags: Dev Biol Source Type: journals

Activation of Ras-ERK pathway by Fgf8 and its downregulation by Sprouty2 for the isthmus organizing activity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the previous studies, we showed that strong Fgf8 signaling activates the Ras-ERK pathway to induce cerebellum. Here, we show importance of negative regulation following activation of this pathway for proper regionalization of mesencephalon and metencephalon in chick embryos. 'Prolonged' activation of ERK by misexpression of Fgf8b and dominant-negative Sprouty2 (dnSprouty2) did not change the fate of the mesencephalic alar plate. Downregulation of ERK activity using a MEK inhibitor, U0126, or by tetracycline dependent Tet-off system after co-expression of Fgf8b and dnSprouty2, forced the mesencephalic alar plate to d...
Source: Developmental Biology - November 5, 2009 Category: Biology Authors: Suzuki-Hirano A, Harada H, Sato T, Nakamura H Tags: Dev Biol Source Type: journals

JAK/STAT signaling coordinates stem cell proliferation and multilineage differentiation in the Drosophila intestinal stem cell lineage.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Adult stem cells are the most primitive cells of a lineage and are distinguished by the properties of self-renewal and multipotency. Coordinated control of stem cell proliferation and multilineage differentiation is essential to ensure a steady output of differentiated daughter cells necessary to maintain tissue homeostasis. However, little is known about the signals that coordinate stem cell proliferation and daughter cell differentiation. Here we investigate the role of the conserved JAK/STAT signaling pathway in the Drosophila intestinal stem cell (ISC) lineage. We show first, that JAK/STAT signaling is normally act...
Source: Developmental Biology - November 5, 2009 Category: Biology Authors: Beebe K, Lee WC, Micchelli CA Tags: Dev Biol Source Type: journals

Gene Switching at Xenopus laevis metamorphosis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During the climax of amphibian metamorphosis many tadpole organs remodel. The different remodeling strategies are controlled by thyroid hormone (TH). The liver, skin, and tail fibroblasts shut off tadpole genes and activate frog genes in the same cell without DNA replication. We refer to this as "gene switching". In contrast, the exocrine pancreas and the intestinal epithelium dedifferentiate to a progenitor state and then redifferentiate to the adult cell type. Tadpole and adult globin are not present in the same cell. Switching from red cells containing tadpole-specific globin to those with frog globin in the liver o...
Source: Developmental Biology - November 5, 2009 Category: Biology Authors: Mukhi S, Cai L, Brown DD Tags: Dev Biol Source Type: journals

Foxh1 and Foxa2 are not required for formation of the midgut and hindgut definitive endoderm.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The definitive endoderm forms during gastrulation and is rapidly transformed into the gut tube which is divided along the anterior-posterior axis into the foregut, midgut, and hindgut. Lineage tracing and genetic analysis has examined the origin of the definitive endoderm during gastrulation and demonstrated that the majority of definitive endoderm arises at the anterior end of the primitive streak (APS). Foxh1 and Foxa2 have been shown to play a role in specification of the APS and definitive endoderm. However, prior studies have focused on the role of these factors in specification of foregut definitive endoderm, whi...
Source: Developmental Biology - November 4, 2009 Category: Biology Authors: McKnight KD, Hou J, Hoodless PA Tags: Dev Biol Source Type: journals

Functionally conserved cis-regulatory elements of COL18A1 identified through zebrafish transgenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Type XVIII Collagen is a component of basement membranes, and expressed prominently in the eye, blood vessels, liver, and the central nervous system. Homozygous mutations in COL18A1 lead to Knobloch Syndrome, characterized by ocular defects and occipital encephalocele. However, relatively little has been described on the role of type XVIII collagen in development, and nothing is known about the regulation of its tissue-specific expression pattern. We have used zebrafish transgenesis to identify and characterize cis-regulatory sequences controlling expression of the human gene. Candidate enhancers were selected from non...
Source: Developmental Biology - November 3, 2009 Category: Biology Authors: Kague E, Bessling SL, Lee J, Hu G, Passos-Bueno MR, Fisher S Tags: Dev Biol Source Type: journals

Vascular Morphogenesis in the Zebrafish Embryo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
During embryonic development the vertebrate vasculature is undergoing vast growth and remodeling. Blood vessels can be formed by a wide spectrum of different morphogenetic mechanisms, such as budding, cord hollowing, cell hollowing, cell wrapping and intussusception. Here, we describe the vascular morphogenesis that occurs in the early zebrafish embryo. We discuss the diversity of morphogenetic mechanisms that contribute to vessel assembly, angiogenic sprouting and tube formation in different blood vessels and how some of these complex cell behaviors are regulated by molecular pathways. PMID: 19895803 [PubMed - as ...
Source: Developmental Biology - November 3, 2009 Category: Biology Authors: Ellertsdóttir E, Lenard A, Blum Y, Krudewig A, Herwig L, Affolter M, Belting HG Tags: Dev Biol Source Type: journals

Pdlim7 (LMP4) regulation of Tbx5 specifies zebrafish heart atrio-ventricular boundary and valve formation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Tbx5 is involved in congenital heart disease, however, the mechanisms leading to organ malformation are greatly unknown. We hypothesized a model by which the Tbx5 binding protein Pdlim7 controls nuclear/cytoplasmic shuttling and function of the transcription factor. Using the zebrafish, we present in vivo significance for an essential role of Tbx5/Pdlim7 protein interaction in the regulation of cardiac formation. Knock-down of Pdlim7 results in a non-looped heart, strikingly reminiscent of the tbx5 heartstrings mutant phenotype. However, while misregulation of Pdlim7 and Tbx5 produce similar aberrant cardiac morphology...
Source: Developmental Biology - November 3, 2009 Category: Biology Authors: Camarata T, Krcmery J, Snyder D, Park S, Topczewski J, Simon HG Tags: Dev Biol Source Type: journals

FoxO genes are dispensable during gastrulation but required for late embryogenesis in Xenopus laevis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Forkhead box (Fox) transcription factors of subclass O are involved in cell survival, proliferation, apoptosis, cell metabolism and prevention of oxidative stress. FoxO genes are highly conserved throughout evolution and their functions were analyzed in several vertebrate and invertebrate organisms. We here report on the identification of FoxO4 and FoxO6 genes in Xenopus laevis and analyze their expression patterns in comparison with the previously described FoxO1 and FoxO3 genes. We demonstrate significant differences in their temporal and spatial expression during embryogenesis and in their relative expression within...
Source: Developmental Biology - November 3, 2009 Category: Biology Authors: Schuff M, Siegel D, Bardine N, Oswald F, Donow C, Knöchel W Tags: Dev Biol Source Type: journals

The endoderm gene regulatory network in sea urchin embryos up to mid-blastula stage.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
As the result of early specification processes, sea urchin embryos eventually form various mesodermal cell lineages and a gut consisting of fore-, mid-and hindgut. The progression of specification as well as the overall spatial organization of the organism is encoded in its gene regulatory networks (GRNs). We have analyzed the GRN driving endoderm specification up to the onset of gastrulation and present in this paper the mechanisms which determine this process up to mid-blastula stage. At this stage, the embryo consists of two separate lineages of endoderm precursor cells with distinct regulatory states. One of these ...
Source: Developmental Biology - November 3, 2009 Category: Biology Authors: Peter IS, Davidson EH Tags: Dev Biol Source Type: journals

Integrin-mediated adhesion maintains sarcomeric integrity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Integrin-mediated adhesion to the ECM is essential for normal development of animal tissues. During muscle development integrins provide the structural stability required to construct such a highly tensile, force generating tissue. Mutations that disrupt integrin-mediated adhesion in skeletal muscles give rise to a myopathy in humans and mice. To determine if this is due to defects in formation or defects in maintenance of muscle tissue we used an inducible, targeted RNAi based approach to disrupt integrin-mediated adhesion in fully formed adult fly muscles. A decrease in integrin-mediated adhesion in adult muscles led...
Source: Developmental Biology - October 28, 2009 Category: Biology Authors: Perkins AD, Ellis SJ, Asghari P, Shamsian A, Moore ED, Tanentzapf G Tags: Dev Biol Source Type: journals

Nanos functions to maintain the fate of the small micromere lineage in the sea urchin embryo.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The translational regulator nanos is required for the survival and maintenance of primordial germ cells during embryogenesis. Three nanos homologs are present in the genome of the sea urchin Strongylocentrotus purpuratus, all of which are expressed with differential timing in the small micromere lineage. This lineage is set-aside during embryogenesis and contributes to constructing the adult rudiment. Small micromeres lacking Sp-nanos1 and Sp-nanos2 undergo an extra division and are not incorporated into the coelomic pouches. Further, these cells do not accumulate Vasa protein even though they retain vasa mRNA. Larvae ...
Source: Developmental Biology - October 27, 2009 Category: Biology Authors: Juliano CE, Yajima M, Wessel GM Tags: Dev Biol Source Type: journals

Making heads from tails: Development of a reversed anterior-posterior axis during budding in an acoel.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The anterior-posterior axis is a key feature of the bilaterian body plan. Although axis specification during embryogenesis has been studied extensively, virtually nothing is known about how this axis can be established post-embryonically, as occurs in budding animals. We investigated bud formation in the acoel Convolutriloba retrogemma, which reproduces by a remarkable process involving the formation of animals with linked but completely opposite body axes. Reverse axes are established anew during each round of budding and manifestations of the bud's new axis develop gradually, with regionalization of axial patterning ...
Source: Developmental Biology - October 27, 2009 Category: Biology Authors: Sikes JM, Bely AE Tags: Dev Biol Source Type: journals

Dhrs3a Regulates Retinoic Acid Biosynthesis through a Feedback Inhibition Mechanism.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Retinoic acid (RA) is an important developmental signaling molecule responsible for the patterning of multiple vertebrate tissues. RA is also a potent teratogen, causing multi-organ birth defects in humans. Endogenous RA levels must therefore be tightly controlled in the developing embryo. We used a microarray approach to identify genes that function as negative feedback regulators of retinoic acid signaling. We screened for genes expressed in early somite-stage embryos that respond oppositely to treatment with RA versus RA antagonists, and validated them by RNA in situ hybridization. Focusing on genes known to be invo...
Source: Developmental Biology - October 26, 2009 Category: Biology Authors: Feng L, Hernandez RE, Waxman JS, Yelon D, Moens CB Tags: Dev Biol Source Type: journals

Kit ligand cytoplasmic domain is essential for basolateral sorting in vivo and has roles in spermatogenesis and hematopoiesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Juxtamembrane signaling via the membrane growth factor KitL is critical for Kit mediated functions. KitL has a conserved cytoplasmic domain, and has been shown to possess a monomeric leucine dependent basolateral targeting signal. To investigate the consequences in vivo of impaired basolateral KitL targeting in polarized epithelial cells, we have mutated this critical leucine to alanine using a knock-in strategy. KitL(L263A/L263A) mutant mice are pigmented normally and steady-state hematopoiesis is unaffected although peritoneal and skin mast cell numbers are significantly increased. KitL localization is affected in th...
Source: Developmental Biology - October 26, 2009 Category: Biology Authors: Deshpande S, Agosti V, Manova K, Moore MA, Hardy MP, Besmer P Tags: Dev Biol Source Type: journals

Challenges for modeling global Gene Regulatory networks during development: insights from Drosophila.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Development is regulated by dynamic patterns of gene expression, which are orchestrated through the action of complex gene regulatory networks (GRNs). Substantial progress has been made in modeling transcriptional regulation in recent years, including qualitative 'coarse-grain' models operating at the gene level to very 'fine-grain' quantitative models operating at the biophysical 'Transcription Factor-DNA level'. Recent advances in genome-wide studies have revealed an enormous increase in the size and complexity or GRNs. Even relatively simple developmental processes can involve hundreds of regulatory molecules, with ...
Source: Developmental Biology - October 26, 2009 Category: Biology Authors: Wilczynski B, Furlong EE Tags: Dev Biol Source Type: journals

Pulsation and stabilization: Contractile forces that underlie morphogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Embryonic development involves global changes in tissue shape and architecture that are driven by cell shape changes and rearrangements within cohesive cell sheets. Morphogenetic changes at the cell and tissue-level require that cells generate forces and that these forces are transmitted between the cells of a coherent tissue. Contractile forces generated by the actin-myosin cytoskeleton are critical for morphogenesis, but the cellular and molecular mechanisms of contraction have been elusive for many cell shape changes and movements. Recent studies that have combined live imaging with computational and biophysical app...
Source: Developmental Biology - October 26, 2009 Category: Biology Authors: Martin AC Tags: Dev Biol Source Type: journals

Cell cycle regulation in the inner ear sensory epithelia: Role of cyclin D1 and cyclin-dependent kinase inhibitors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sensory hair cells and supporting cells of the mammalian cochlea and vestibular (balance) organs exit the cell cycle during embryogenesis and do not proliferate thereafter. Here, we have studied the mechanisms underlying the maintenance of the postmitotic state and the proliferative capacity of these cells. We provide the first evidence of the role of cyclin D1 in cell cycle regulation in these cells. Cyclin D1 expression disappeared from embryonic hair cells as differentiation started. The expression was transiently upregulated in cochlear hair cells early postnatally, paralleling the spatiotemporal pattern of unsched...
Source: Developmental Biology - October 22, 2009 Category: Biology Authors: Laine H, Sulg M, Kirjavainen A, Pirvola U Tags: Dev Biol Source Type: journals

The Extracellular Matrix In Development and Morphogenesis: A Dynamic View.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The extracellular matrix (ECM) is synthesized and secreted by embryonic cells beginning at the earliest stages of development. Our understanding of ECM composition, structure and function has grown considerably in the last several decades and this knowledge has revealed that the extracellular microenvironment is critically important for cell growth, survival, differentiation and morphogenesis. ECM and the cellular receptors that interact with it mediate both physical linkages with the cytoskeleton and the bidirectional flow of information between the extracellular and intracellular compartments. This review considers t...
Source: Developmental Biology - October 22, 2009 Category: Biology Authors: Rozario T, Desimone DW Tags: Dev Biol Source Type: journals

The Zn Finger protein Iguana impacts Hedgehog signaling by promoting ciliogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Hedgehog signaling is critical for metazoan development and requires cilia for pathway activity. The gene iguana was discovered in zebrafish as required for Hedgehog signaling, and encodes a novel Zn finger protein. Planarians are flatworms with robust regenerative capacities and that utilize epidermal cilia for locomotion. RNA interference of Smed-iguana in the planarian S. mediterranea caused cilia loss and failure to regenerate new cilia, but did not cause defects similar to those observed in hedgehog(RNAi) animals. Smed-iguana gene expression was also similar in pattern to the expression of multiple other ciliogene...
Source: Developmental Biology - October 20, 2009 Category: Biology Authors: Glazer A, Wilkinson A, Backer CB, Lapan S, Gutzman JH, Cheeseman IM, Reddien PW Tags: Dev Biol Source Type: journals

Wnt/Lef1 signaling acts via Pitx2 to regulate somite myogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Wnt signalling has been implicated in somite, limb and branchial arch myogenesis but the mechanisms and roles are not clear. We now show that Wnt signalling via Lef1 acts to regulate the number of premyogenic cells in somites but does not regulate myogenic initiation in the limb bud or maintenance in the first or second branchial arch. We have also analysed the function and regulation of a putative down-stream transcriptional target of canonical Wnt signalling, Pitx2. We show that loss of function of Pitx2 decreases the number of myogenic cells in the somite, whereas overexpression increases myocyte number particularly...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Abu-Elmagd M, Robson L, Sweetman D, Hadley J, Francis-West P, Münsterberg A Tags: Dev Biol Source Type: journals

Gata4 directs development of cardiac-inducing endoderm from ES cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transcription factor Gata4 is essential for normal heart morphogenesis and regulates the survival, growth, and proliferation of cardiomyocytes. We tested if Gata4 can specify cardiomyocyte fate from an uncommitted stem or progenitor cell population, by developing a system for conditional expression of Gata4 in embryonic stem cells. We find that in embryoid body cultures containing even a low ratio of these cells, expression of Gata4 is sufficient to enhance significantly the generation of cardiomyocytes, via a non-cell-autonomous mechanism. The Gata4-expressing cells do not generate cardiac or other mesoderm deriva...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Holtzinger A, Rosenfeld GE, Evans T Tags: Dev Biol Source Type: journals

Regulation of Smoothened by Drosophila G-protein-coupled receptor kinases.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Hedgehog (Hh) signaling pathway plays a conserved and essential role in regulating development and homeostasis of numerous tissues. Cytoplasmic signaling is initiated by Smoothened (Smo), a G-protein-coupled receptor (GPCR) family member, whose levels and activity are regulated by the Hh receptor Patched (Ptc). In response to Hh binding to Ptc, Ptc-mediated repression of Smo is relieved, leading to Smo activation, surface accumulation, and downstream signaling. We find that downregulation of Drosophila Smo protein in Hh-responding imaginal disc cells is dependent on the activity of G-protein-coupled receptor kinase...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Cheng S, Maier D, Neubueser D, Hipfner DR Tags: Dev Biol Source Type: journals

Autocrine and paracrine Shh signaling are necessary for tooth morphogenesis, but not tooth replacement in snakes and lizards (Squamata).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Here we study the role of Shh signaling in tooth morphogenesis and successional tooth development in snakes and lizards (Squamata). By characterizing the expression of Shh pathway receptor Ptc1 in the developing dentitions of three species (Eublepharis macularius, Python regius, and Pogona vitticeps) and by performing gain- and loss-of-function experiments, we demonstrate that Shh signaling is active in the squamate tooth bud and is required for its normal morphogenesis. Shh apparently mediates tooth morphogenesis by separate paracrine- and autocrine-mediated functions. According to this model, paracrine Shh signaling ...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Handrigan GR, Richman JM Tags: Dev Biol Source Type: journals

Germline Cyst Formation and Incomplete Cytokinesis During Drosophila melanogaster Oogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Germline cyst formation via incomplete cytokinesis (IC) is necessary to generate functional eggs and sperm in various organisms. D. melanogaster oogenesis is an ideal system for studying IC. 29 stages of germline cyst formation can be identified in D. melanogaster oogenesis. We have defined necessary terminology to describe IC and have developed a method to measure the sizes of contractile rings and ring canals. Time course study of germline cyst formation demonstrates that contractile ring constriction proceeds to a defined end point unique for each mitotic division. Contractile rings constrict to a greater degree, re...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Ong S, Tan C Tags: Dev Biol Source Type: journals

A critical role for sFRP proteins in maintaining caudal neural tube closure in mice via inhibition of BMP signaling.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we provide genetic and functional evidence that the secreted sFRP1 and sFRP2 proteins, which have been primarily implicated as negative regulators of Wnt signaling, can also antagonize BMP signaling in the caudal neural tube, and that this function is critical to maintain proper neural tube closure and dorsal cell fate segregation. Our studies thus reveal a novel role for specific sFRP proteins in balancing the response of cells to two critical extracellular signaling pathways. PMID: 19850029 [PubMed - as supplied by publisher] (Source: Developmental Biology)
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Misra K, Matise MP Tags: Dev Biol Source Type: journals

Mast cells contribute to the stromal microenvironment in mammary gland branching morphogenesis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The stromal microenvironment regulates mammary gland branching morphogenesis. We have observed that mast cells are present in the mammary gland throughout its postnatal development and in particular, are found around the terminal end buds and ductal epithelium of the pubertal gland. Mast cells contribute to allergy, inflammatory diseases, and cancer development, but have not been implicated in normal development. Genetic and pharmacological disruption of mast cell function in the mammary gland revealed that mast cells are involved in rapid proliferation and normal duct branching during puberty, and this effect is indep...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Lilla JN, Werb Z Tags: Dev Biol Source Type: journals

A systematic approach to identify functional motifs within vertebrate developmental enhancers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Uncovering the cis-regulatory logic of developmental enhancers is critical to understanding the role of non-coding DNA in development. However, it is cumbersome to identify functional motifs within enhancers, and thus few vertebrate enhancers have their core functional motifs revealed. Here we report a combined experimental and computational approach for discovering regulatory motifs in developmental enhancers. Making use of the zebrafish gene expression database, we computationally identified conserved non-coding elements (CNEs) likely to have a desired tissue-specificity based on the expression of nearby genes. Throu...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Li Q, Ritter D, Yang N, Dong Z, Li H, Chuang JH, Guo S Tags: Dev Biol Source Type: journals

The evolution of class V POU domain transcription factors in vertebrates and their characterisation in a marsupial.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
POU5F1 (OCT4) encodes a master regulator of pluripotency that is present in all mammals. A paralogue, POU2, is also present in the genomes of marsupials and monotremes and is an orthologue of zebrafish pou2 and chicken POUV. We explored the evolution of class V POU domain transcription factors and show that POU5F1 arose by gene duplication of pou2 early in the evolution of tetrapods and is not mammal-specific, as previously thought. Instead, either POU5F1 or POU2/POUV has become extinct independently in various lineages, although all gnathostomes appear to possess at least one or the other. In the tammar wallaby, POU5F...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Frankenberg S, Pask A, Renfree MB Tags: Dev Biol Source Type: journals

In vivo analysis in Drosophila reveals differential requirements of contact residues in Axin for interactions with GSK3beta or beta-catenin.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Proper regulation of the Wingless/Wnt signaling pathway is essential for normal development. The scaffolding protein Axin plays a key role in this process through interactions with Drosophila Shaggy and Armadillo. In the current studies, we used a yeast two-hybrid assay to identify ten amino acids in Axin that are critical for in vitro interaction with Shaggy and two for interaction with Armadillo. We then generated five Axin variants in which individual putative contact amino acids were mutated and compared their activity, as assayed by rescue of axin null mutant flies, to that of Axin lacking the entire Shaggy (AxinD...
Source: Developmental Biology - October 19, 2009 Category: Biology Authors: Kremer SA, Erdeniz N, Peterson-Nedry W, Swanson EA, Wehrli M Tags: Dev Biol Source Type: journals