Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Body Patterning”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,549 records · Page 86Linked to original sources
PubMed2000

Sonic hedgehog-mediated ventralization disrupts formation of the midbrain-hindbrain junction in the chick embryo.

The secreted signaling molecule Sonic hedgehog (Shh) plays critical roles in pattern formation of the vertebrate central nervous system. During neurulation, Shh is produced by the ventral midline mesoderm as well as by the ventral neural tube, and its activity is required for the determination of ventral characteristics along the anterior-posterior neuraxis. The morphological boundary between midbrain and hindbrain, the isthmus, is an important tissue organizer that regulates the development of both the midbrain and the anterior hindbrain. In this study, we report that retrovirus-mediated misexpression of Shh in the early chick neural tube disrupts formation of the boundary between the midbrain and the hindbrain, and causes a fusion of the bilateral cerebellum primordia. Dorsally expressed Shh signals induce ectopic transcription of its receptor Ptc1 in the midbrain and the hindbrain. The expression of several genes (Noggin, Lmx1, BMP7) along the dorsal midline of the midbrain is abolished, and ventral or lateral markers (HNF3 beta, Ptc1, ELF1) are induced in the dorsal brain. Furthermore, the normally restricted expression of two genes (En1 and Pax2) in the mid/hindbrain junction region are expanded, reflecting the morphological defects. These results suggest that maintaining proper dorsal-ventral patterns of the neural tube is essential for normal development of the mid/hindbrain region.

Animals↗
PubMed1997

Mechanisms of dorsal-ventral patterning in noggin-induced neural tissue.

We have investigated mechanisms of dorsal-ventral patterning of neural tissue, using Xenopus ectoderm neuralized by noggin protein. This tissue appears to be patterned dorsoventrally; cp1-1, a gene expressed in the dorsal brain, and etr-1, a gene largely excluded from the dorsal brain, are expressed in separate territories in noggin-treated explants (Knecht, A. K., Good, P. J., Dawid, I. B. and Harland, R. M. (1995) Development 121, 1927-1936). Here we show further evidence that this pattern represents a partial dorsal-ventral organization. Additionally, we test two mechanisms that could account for this pattern: a dose-dependent response to a gradient of noggin protein within the explant, and regulative cell-cell interactions. We show that noggin exhibits concentration-dependent effects, inducing cp1-1 at low doses but repressing it at high doses. Since noggin acts by antagonizing Bone Morphogenetic Protein (BMP) signaling, this result suggests that BMPs also may act in a dose-dependent manner in vivo. However, in the absence of a noggin gradient, regulative cell-cell interactions can also pattern the tissue. Such regulation is facilitated by increased motility of noggin-treated cells. Finally, the response of cells to both of these patterning mechanisms is ultimately controlled by a third process, the changing competence of the responding tissue.

Animals↗
PubMed1998

Complete dissipation of coherent clonal growth occurs before gastrulation in mouse epiblast.

Observations on chimaeric mice argue that there must be considerable dispersal and intermingling of the clonal descendants of epiblast founder cells at an early stage in the development of the tissue. However, it has not been established when or how this occurs. Here we have used a genetic marker that enables donor cells to be visualized in situ to examine the early postimplantation distribution of clones obtained by transplanting epiblast founder cells into host blastocysts. We have also determined the spatial relationship between sister cells in non-chimaeric postimplantation epiblast by ionophoretic injection of a fluorescent macromolecule. Both experimental approaches support the conclusion that breakdown of coherent clonal growth accompanies epithelialization of the epiblast and is essentially complete by the onset of gastrulation. Furthermore, the clonal analysis shows that descendants of different epiblast founder cells continue to intermingle extensively well into organogenesis. We suggest that this sustained intermingling of cells in the epithelial epiblast, which does not occur in the adjacent visceral endoderm, depends on cells losing contact with the basal lamina when they divide. These findings have implications both for patterning of the early amniote embryo and for the growth of tall columnar epithelia in general.

Animals↗
PubMed1999

Differential patterning of ventral midline cells by axial mesoderm is regulated by BMP7 and chordin.

Ventral midline cells in the neural tube have distinct properties at different rostrocaudal levels, apparently in response to differential signalling by axial mesoderm. Floor plate cells are induced by sonic hedgehog (SHH) secreted from the notochord whereas ventral midline cells of the rostral diencephalon (RDVM cells) appear to be induced by the dual actions of SHH and bone morphogenetic protein 7 (BMP7) from prechordal mesoderm. We have examined the cellular and molecular events that govern the program of differentiation of RDVM cells under the influence of the axial mesoderm. By fate mapping, we show that prospective RDVM cells migrate rostrally within the neural plate, passing over rostral notochord before establishing register with prechordal mesoderm at stage 7. Despite the co-expression of SHH and BMP7 by rostral notochord, prospective RDVM cells appear to be specified initially as caudal ventral midline neurectodermal cells and to acquire RDVM properties only at stage 7. We provide evidence that the signalling properties of axial mesoderm over this period are regulated by the BMP antagonist, chordin. Chordin is expressed throughout the axial mesoderm as it extends, but is downregulated in prechordal mesoderm coincident with the onset of RDVM cell differentiation. Addition of chordin to conjugate explant cultures of prechordal mesoderm and neural tissue prevents the rostralization of ventral midline cells by prechordal mesoderm. Chordin may thus act to refine the patterning of the ventral midline along the rostrocaudal axis.

Animals↗
PubMed2000

Extraocular mesenchyme patterns the optic vesicle during early eye development in the embryonic chick.

The vertebrate eye develops from the neuroepithelium of the ventral forebrain by the evagination and formation of the optic vesicle. Classical embryological studies have shown that the surrounding extraocular tissues - the surface ectoderm and extraocular mesenchyme - are necessary for normal eye growth and differentiation. We have used explant cultures of chick optic vesicles to study the regulation of retinal pigmented epithelium (RPE) patterning and differentiation during early eye development. Our results show that extraocular mesenchyme is required for the induction and maintenance of expression of the RPE-specific genes Mitf and Wnt13 and the melanosomal matrix protein MMP115. In the absence of extraocular tissues, RPE development did not occur. Replacement of the extraocular mesenchyme with cranial mesenchyme, but not lateral plate mesoderm, could rescue expression of the RPE-marker Mitf. In addition to activating expression of RPE-specific genes, the extraocular mesenchyme inhibits the expression of the neural retina-specific transcription factor Chx10 and downregulates the eye-specific transcription factors Pax6 and Optx2. The TGF(&bgr;) family member activin can substitute for the extraocular mesenchyme by promoting expression of the RPE-specific genes and downregulating expression of the neural retina-specific markers. These data indicate that extraocular mesenchyme, and possibly an activin-like signal, pattern the domains of the optic vesicle into RPE and neural retina.

Animals↗
PubMed2001

Early embryo patterning in the grasshopper, Schistocerca gregaria: wingless, decapentaplegic and caudal expression.

Although the molecular pathways that pattern the early embryo of Drosophila melanogaster are well understood, how these pathways differ in other types of insect embryo remains largely unknown. We have examined the expression of three markers of early patterning in the embryo of the African plague locust Schistocerca gregaria, an orthopteran insect that displays a mode of embryogenesis very different from that of Drosophila. Transcripts of the caudal gene are expressed maternally and are present in all cells that aggregate to form the early embryonic rudiment. First signs of a posterior-to-anterior gradient in the levels of caudal transcript appear in the early heart-stage embryo, shortly before gastrulation. This gradient rapidly resolves to a defined expression domain marking segment A11. The decapentaplegic (dpp) gene, which encodes a transforming growth factor beta family ligand, is first expressed in a circle of cells that delimit the margins of the embryonic primordium, where embryonic and extra-embryonic tissues abut. Patterned transcription of wingless reveals that the first segments are delineated in the Schistocerca embryo substantially earlier than previously thought, at least 14-16 hours before the onset of engrailed expression. By the late heart-stage, gnathal and thoracic segments are all defined. Thus, with respect to the molecular patterning of segments, the short germ Schistocerca embryo differs little from intermediate germ embryos. The expression of these marker genes suggests that embryonic pattern formation in the grasshopper occurs as cells move together to form the blastodisc.

Amino Acid Sequence↗
PubMed2001

Grasshopper hunchback expression reveals conserved and novel aspects of axis formation and segmentation.

While the expression patterns of segment polarity genes such as engrailed have been shown to be similar in Drosophila melanogaster and Schistocerca americana (grasshopper), the expression patterns of pair-rule genes such as even-skipped are not conserved between these species. This might suggest that the factors upstream of pair-rule gene expression are not conserved across insect species. We find that, despite this, many aspects of the expression of the Drosophila gap gene hunchback are shared with its orthologs in the grasshoppers S. americana and L. migratoria. We have analyzed both mRNA and protein expression during development, and find that the grasshopper hunchback orthologs appear to have a conserved role in early axial patterning of the germ anlagen and in the specification of gnathal and thoracic primordia. In addition, distinct stepped expression levels of hunchback in the gnathal/thoracic domains suggest that grasshopper hunchback may act in a concentration-dependent fashion (as in Drosophila), although morphogenetic activity is not set up by diffusion to form a smooth gradient. Axial patterning functions appear to be performed entirely by zygotic hunchback, a fundamental difference from Drosophila in which maternal and zygotic hunchback play redundant roles. In grasshoppers, maternal hunchback activity is provided uniformly to the embryo as protein and, we suggest, serves a distinct role in distinguishing embryonic from extra-embryonic cells along the anteroposterior axis from the outset of development - a distinction made in Drosophila along the dorsoventral axis later in development. Later hunchback expression in the abdominal segments is conserved, as are patterns in the nervous system, and in both Drosophila and grasshopper, hunchback is expressed in a subset of extra-embryonic cells. Thus, while the expected domains of hunchback expression are conserved in Schistocerca, we have found surprising and fundamental differences in axial patterning, and have identified a previously unreported domain of expression in Drosophila that suggests conservation of a function in extra-embryonic patterning.

Amino Acid Sequence↗
PubMed2001

Gsh2 and Pax6 play complementary roles in dorsoventral patterning of the mammalian telencephalon.

The telencephalon has two major subdivisions, the pallium and subpallium. The pallium, which primarily consists of glutamatergic cortical structures, expresses dorsal molecular markers, whereas the subpallium, which primarily consists of the GABAergic basal ganglia, expresses ventral molecular markers. Here, we present evidence that the progenitor and postmitotic cells flanking the pallial/subpallial boundary (PSB) in the embryonic mouse can be subdivided into multiple regions that express unique combinations of transcription factors. The domains that immediately flank the PSB are the ventral pallium (VP) and the dorsal lateral ganglionic eminence (dLGE). The early expression of the Pax6 and Gsh2 homeobox transcription factors overlaps in the region of the dLGE. Analyses of mice that lack functional alleles of either Gsh2 or Pax6 demonstrate that these genes have complementary roles in patterning the primordia flanking the PSB. In the Gsh2 mutants, the dLGE is respecified into a VP-like structure, whereas in the Pax6 mutants the VP is respecified into a dLGE-like structure. The role of Pax6 in dorsalizing the telencephalon is similar to its role in the spinal cord, supporting the hypothesis that some dorsoventral patterning mechanisms are used at all axial levels of the central nervous system.

Animals↗
PubMed2002

Six3 inactivation reveals its essential role for the formation and patterning of the vertebrate eye.

The establishment of retinal identity and the subsequent patterning of the optic vesicle are the key steps in early vertebrate eye development. To date little is known about the nature and interaction of the genes controlling these steps. So far few genes have been identified that, when over-expressed, can initiate ectopic eye formation. Of note is Six3, which is expressed exclusively in the anterior neural plate. However, 'loss of function' analysis has not been reported. Using medaka fish, we show that vertebrate Six3 is necessary for patterning of the anterior neuroectoderm including the retina anlage. Inactivation of Six3 function by morpholino knock-down results in the lack of forebrain and eyes. Corroborated by gain-of-function experiments, graded interference reveals an additional role of Six3 in the proximodistal patterning of the optic vesicle. During both processes of vertebrate eye formation, Six3 cooperates with Pax6.

Animals↗
PubMed2006

Threshold-dependent BMP-mediated repression: a model for a conserved mechanism that patterns the neuroectoderm.

Subdivision of the neuroectoderm into three rows of cells along the dorsal-ventral axis by neural identity genes is a highly conserved developmental process. While neural identity genes are expressed in remarkably similar patterns in vertebrates and invertebrates, previous work suggests that these patterns may be regulated by distinct upstream genetic pathways. Here we ask whether a potential conserved source of positional information provided by the BMP signaling contributes to patterning the neuroectoderm. We have addressed this question in two ways: First, we asked whether BMPs can act as bona fide morphogens to pattern the Drosophila neuroectoderm in a dose-dependent fashion, and second, we examined whether BMPs might act in a similar fashion in patterning the vertebrate neuroectoderm. In this study, we show that graded BMP signaling participates in organizing the neural axis in Drosophila by repressing expression of neural identity genes in a threshold-dependent fashion. We also provide evidence for a similar organizing activity of BMP signaling in chick neural plate explants, which may operate by the same double negative mechanism that acts earlier during neural induction. We propose that BMPs played an ancestral role in patterning the metazoan neuroectoderm by threshold-dependent repression of neural identity genes.

Animals↗
PubMed2003

Developmental basis for vein pattern variations in insect wings.

The venation patterns characteristics of different insect orders and of families belonging to the same order possess enormous variation in vein number, position and differentiation. Although the developmental basis of changes in vein patterns during evolution is entirely unknown, the identification of the genes and developmental processes involved in Drosophila vein pattern formation facilitates the elaboration of construction rules. It is thus possible to identify the likely changes which may constitute a source of pattern variation during evolution. In this review, we discuss how actual patterns of venation could be accounted for by modifications in different Pterygota of a common set of developmental operations. We argue that the individual specification of each vein and the modular structure of the regulatory regions of the key genes identified in Drosophila offer candidate entry points for pattern modifications affecting individual veins or interveins independently. Assuming a general conservation of the processes involved in different species, the transitions between different patterns may require few changes in the regulatory gene networks involved.

Animals↗
PubMed1998

UNC-55, an orphan nuclear hormone receptor, orchestrates synaptic specificity among two classes of motor neurons in Caenorhabditis elegans.

Loss of UNC-55 function in the nematode Caenorhabditis elegans causes one motor neuron class, the ventral D (VD) motor neurons, to adopt the synaptic pattern of another motor neuron class, the dorsal D (DD) motor neurons. Here we show that unc-55 encodes a member of the nuclear hormone receptor gene family that is similar to the vertebrate chicken ovalbumin upstream promoter transcription factors. Although the VD and DD motor neuron classes arise from different lineages at different developmental stages, they share a number of structural and functional features that appear to be the product of identical genetic programs. UNC-55 is expressed in the VD but not the DD motor neurons to modify this genetic program and to create the synaptic pattern that distinguishes the two motor neuron classes from one another.

Amino Acid Sequence↗
PubMed1990

Electrogenesis of the S1S2S3 electrocardiographic pattern. A study in humans based on body surface potential and right ventricular endocardial mapping.

To study the electrogenesis of the S1S2S3 pattern, seven patients had body surface potential mapping and endocardial mapping of inflow tract, outflow tract, and apex of the right ventricle. QRS duration was longer in S1S2S3 versus controls (94 +/- 14 vs. 84 +/- 14 msec). Surface mapping was similar in S1S2S3 patients and in controls during the first 30-40 msec of QRS, but S1S2S3 patients subsequently presented the following differences: (1) earlier time of onset (34 +/- 3 vs. 44 +/- 6 msec) and a lower voltage (1,242 +/- 468 vs. 1,649 +/- 31 mV) of peak positive anterior maximum; (2) earlier dorsal migration (45 +/- 3 vs. 55 +/- 7 msec) of the maximum; (3) a second peak positive maximum at 58 +/- 3 msec, located on the dorsal spine; (4) the appearance of a right subclavicular positive area at 51 +/- 6 msec, which in controls was absent or appeared later (66 +/- 7 msec). At the end of QRS, the maximum was located in all but two S1S2S3 cases on the upper sternum. Right ventricular endocardial mapping showed a similar activation time of the apex in S1S2S3 patients and controls, but in the former a significant inflow (56 +/- 21 vs. 36 +/- 9 msec) and outflow tract (79 +/- 13 vs. 39 +/- 8 msec) activation delay was documented. The data obtained using body surface potential mapping suggest that an anomalous wavefront rightward and superiorly oriented is present in the S1S2S3 pattern, which is able to oppose the electrical forces of ventricular free walls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

A system for the automated recording of feeding behavior and body weight.

A method that uses passive integrated transponder (PIT) tags for the continuous recording of feeding behavior and body weight from multiple individual animals is described. We have used this method in the field and in semi-natural captive conditions with black-capped chickadees (Poecile atricapillus) to determine daily and seasonal patterns in body weight and to estimate the proportions of food cached and consumed.

Animals↗
PubMed2004

Blood vessel patterning at the embryonic midline.

The reproducible pattern of blood vessels formed in vertebrate embryos has been described extensively, but only recently have we obtained the genetic and molecular tools to address the mechanisms underlying these processes. This review describes our current knowledge regarding vascular patterning around the vertebrate midline and presents data derived from frogs, zebrafish, avians, and mice. The embryonic structures implicated in midline vascular patterning, the hypochord, endoderm, notochord, and neural tube, are discussed. Moreover, several molecular signaling pathways implicated in vascular patterning, VEGF, Tie/tek, Notch, Eph/ephrin, and Semaphorin, are described. Data showing that VEGF is critical to patterning the dorsal aorta in frogs and zebrafish, and to patterning the vascular plexus that forms around the neural tube in amniotes, is presented. A more complete knowledge of vascular patterning is likely to come from the next generation of experiments using ever more sophisticated tools, and these results promise to directly impact on clinically important issues such as forming new vessels in the human body and/or in bioreactors.

Animals↗
PubMed1984

Energy depot replenishment in rats during refeeding after fasting: effect of exercise.

The effect of progressive moderate exercise on body weight gain, visceral and muscle protein stores, and thyroid hormone levels during an 8-day refeeding period after 65 h of starvation was studied in 2-month-old male Sprague-Dawley rats. Twenty-four animals were divided into three groups and acclimated for 5 days while being fed with ordinary Purina Chow. After the fasting phase, a group of rats was killed in order to provide base-line information concerning fasting-induced changes in body composition; a sedentary group was fed Purina Chow ad libitum; and a treadmill-exercised group was pair fed with the sedentary rats. During the refeeding phase, the exercised animals regained significantly less weight than the sedentary animals (p less than 0.001), but the two groups did not differ significantly with respect to visceral, muscle, eviscerated carcass, and skin protein. Total body fat content was lower in the exercised than the sedentary group. The thyroid hormone levels were not significantly different for the two refed groups. These results indicate that exercise during refeeding may alter the pattern of body weight gain during refeeding after fasting such that the replenishment of adipose tissue stores is reduced without compromising the restoration and growth of lean tissue.

Adipose Tissue↗
PubMed2000

Regulation of the Hoxa4 and Hoxa5 genes in the embryonic mouse lung by retinoic acid and TGFbeta1: implications for lung development and patterning.

We have previously described a 5; cis-acting retinoic acid response element that is required for a subset of Hoxa4 expression, including the midgestation mouse lung. As both retinoids and Hox genes have been implicated in lung development and patterning, we have examined Hoxa4 expression in the developing mouse lung and extended our work on its regulation. At E12.5, a Hoxa4/lacZ transgene is expressed in the mesenchymal compartment of the lung. Later in development expression is restricted to the proximal mesenchyme and is also observed in smooth muscle cells, subepithelial fibroblasts, and alveolar cells. We show that both Hoxa4 and Hoxa5 are upregulated when cultured in the presence of all-trans retinoic acid. In addition, retinoic acid extends the domain of Hoxa4 and Hoxa5 expression to the periphery of the explants where the distal epithelia are developing. Interestingly, the effect of retinoic acid on Hoxa5 expression was not observed in a Hoxa4 mutant background. In contrast, TGFbeta1 was found to downregulate both Hoxa4 and Hoxa5 expression in cultured lung explants. We also establish that retinoic acid has the effect of proximalizing the mouse lung when cultured in a serum-free medium, as evidenced by reduced expression of the distal marker surfactant protein-C. Lungs from Hoxa4 mutant embryos exhibited a similar response to retinoic acid, suggesting that Hoxa4 alone is not required for the proximalizing effect. Based on their retinoid-dependent expression, we conclude that members of the group 4 and/or group 5 Hox genes are likely to be involved in patterning of the mouse lung. Dev Dyn 2000;217:62-74.

Animals↗
PubMed2003

Expression of the type III TGFbeta receptor during chick organogenesis.

Transforming growth factor beta (TGFbeta) is a regulator of embryonic development. The role of specific TGFbeta receptors is emerging, and a unique role for the type III TGFbeta receptor (TBRIII) has been suggested. We report the pattern of TBRIII expression in chicken embryos from 2 to 14 days in ovo.

Animals↗