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You searched for +publisher:"Universiteit Utrecht" +contributor:("Durston, A.J."). Showing records 1 – 2 of 2 total matches.

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Universiteit Utrecht

1. Rieden, P.M.J. in der. Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis.

Degree: 2003, Universiteit Utrecht

The Hox genes form a subset of the homeobox containing genes. The homeobox encodes a DNA binding motif, called the homeodomain. It has been firmly established that Hox expression boundaries along the AP and other embryonic axes are correlated with structural identities. Generating correct Hox expression patterns is thus clearly essential for correct AP axis patterning. The aim of investigations presented in this thesis has been to gain more insight into the processes controlling expression and function of Hox genes during anteroposterior patterning. Recent work in our research group has shown that a temporally colinear expression sequence of Hox genes is already present in the mesoderm of Xenopus gastrulae. Most, if not all, previous work concerning Hox colinearity has been focused on colinear Hox gene expression in the neurectoderm. In chapter two, we present data to show that Xwnt8 is directly upstream of Hoxd1 in mesoderm. This is the first example of an initiator of expression of a 3 Hox gene in a vertebrate embryo. An upstream regulator of Hox gene expression in the neurectoderm of vertebrates is retinoic acid (RA) (and or its derivatives). Retinoids can act via the nuclear receptors of the RAR and RXR family. Retinoic Acid Response Elements (RAREs) have been found in the regulatory sequences of a number of labial- and deformed group Hox genes. We searched for conserved RAREs in the Hox clusters of mouse and human, and the results are reported in chapter three. Most Hox proteins contain a second conserved domain, in addition to the homeodomain, the hexapeptide. This domain is mediates Hox/PBC interaction; this interaction leads to increased binding specificity and -affinity. Sequence analysis of Hox proteins demonstrates interspecies sequence conservation among paralog group members in the hexapeptide-flanking sequences, which is reported in chapter four. Meis/PBC interaction leads to shielding of the nuclear export signal of PBC proteins, resulting in a net influx into the nucleus, modifying the activity of Hox proteins present. In zebrafish hindbrain development, a synergistic relation between Hoxb1, Pbx4, and Meis3 has been shown, and was argued to directly induce the expression of Hoxb1. Since recent discoveries have shown that Hox genes are expressed in a colinear sequence in marginal zone mesoderm we investigated whether a Xenopus Meis homolog, XMeis3, cooperates with Hox function during gastrula stages. In chapter five, we report that XMeis3 is necessary for mesodermal and ectodermal Hox expression, and the progression of gastrulation. In chapter six, conservation of hexapeptide-flanking sequences of Pdx1 and Cdx proteins, present in a wide range of species, resembling the conservation found in Hox group 1 through 8 proteins (Chapter four) is reported. More generally the presence of a hexapeptide sequences and conservation of flanking sequences in all of the members of the Antp-class of homeodomain proteins was investigated, and found to be widely distributed, in addition, hexapeptide-flanking… Advisors/Committee Members: Durston, A.J..

Subjects/Keywords: Biologie; embryonic development; anteroposterior patterning; Hox genes; Meis; Wnt; hexapeptide; retinoids; gastrulation; signalling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Rieden, P. M. J. i. d. (2003). Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis. (Doctoral Dissertation). Universiteit Utrecht. Retrieved from http://dspace.library.uu.nl:8080/handle/1874/229

Chicago Manual of Style (16th Edition):

Rieden, P M J in der. “Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis.” 2003. Doctoral Dissertation, Universiteit Utrecht. Accessed November 20, 2019. http://dspace.library.uu.nl:8080/handle/1874/229.

MLA Handbook (7th Edition):

Rieden, P M J in der. “Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis.” 2003. Web. 20 Nov 2019.

Vancouver:

Rieden PMJid. Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis. [Internet] [Doctoral dissertation]. Universiteit Utrecht; 2003. [cited 2019 Nov 20]. Available from: http://dspace.library.uu.nl:8080/handle/1874/229.

Council of Science Editors:

Rieden PMJid. Control of Hox gene regulation and function during anteroposterior patterning in Xenopus laevis. [Doctoral Dissertation]. Universiteit Utrecht; 2003. Available from: http://dspace.library.uu.nl:8080/handle/1874/229


Universiteit Utrecht

2. Peres, João Nuno Borges Baptista. Divide and conquer: Segmentation and patterning of the anteroposterior axis.

Degree: 2005, Universiteit Utrecht

The formation of the anteroposterior (AP) axis is one of the key events that occur during embryogenesis. Here we investigate the dual processes of patterning and segmentation of the AP axis. To study the role of Hox genes in AP patterning, we decided to analyse the function of the PG1 (paralogous group 1) genes (Hoxa1, -b1, and -d1), the first Hox genes to be expressed in the embryo (Chapter II). PG1 genes are expressed in a widely overlapping domain in the future hindbrain and its associated neural crest. To overcome the functional redundancy of the Hox genes we knocked down the complete paralogous group using morpholinos (MOs) against all three PG1 genes. In the triple PG1 knockdown embryos, the hindbrain lacks segments and the posterior expansion of the rhombomere 1 (r1) marker, Gbx-2, suggests that in the absence of Hox PG1 expression the hindbrain acquires an r1-like fate. This effect could be due to the reduction of other Hox genes, as we show that the ‘Hox code’ is severely perturbed in the PG1 knockdown. Furthermore, PG1 function is also necessary for the migration of the neural crest cells and the formation of the gill cartilages. In Chapter III we study the expression and function of X-Delta-2, one of the genes shown previously to be involved in the somitogenesis of Xenopus laevis. We show that X-Delta-2 pre-patterns the presomitic mesoderm (PSM) from the end of gastrulation on, much earlier than the formation of the first pair of somites. The expression analysis suggests that X-Delta-2 is oscillating in the posterior part of the PSM, leading to the formation of a stripe of expression marking the presumptive somites. Complementary to the expression in the paraxial mesoderm, X-Delta-2 is also expressed in the central nervous system (CNS) and in the cranial placodes. Loss of function studies showed that X-Delta-2 is also involved in hindbrain segmentation and in regulating gene expression throughout the brain. Furthermore, X-Delta-2 also seems to be involved in the determination of eye size and in the neurogenesis and migration of the cranial placode cells. In vertebrates, somites are formed by segmentation of the Hox expressing paraxial mesoderm. Hox genes confer specific identity to the somites, and their anterior boundaries are maintained at the same somite number. This suggests that somitogenesis and AP patterning are coordinated at some level. In Chapter IV we study the interaction between these two events, and more precisely between X-Delta-2 and PG1 genes. We show that besides its role in segmentation, X-Delta-2 is also vital for Hox gene expression. X-Delta-2 function is necessary for both ectodermal and mesodermal expression, not only during somitogenesis, as previously shown, but also during gastrulation when the 'Hox code' starts to be set. We also show evidence that the regulation of Hox genes is via the intracellular domain of X-Delta-2, and not via the Notch receptor, as is the case in the somitogenesis process. For the first time evidence is shown for a clear involvement of the Hox genes… Advisors/Committee Members: Durston, A.J..

Subjects/Keywords: Biologie; segmentation; somitogenesis; Hox genes; anteroposterior patterning; X-Delta-2; CNS; hindbrain; placodes; PG1; neural crest

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Peres, J. N. B. B. (2005). Divide and conquer: Segmentation and patterning of the anteroposterior axis. (Doctoral Dissertation). Universiteit Utrecht. Retrieved from http://dspace.library.uu.nl:8080/handle/1874/7295

Chicago Manual of Style (16th Edition):

Peres, João Nuno Borges Baptista. “Divide and conquer: Segmentation and patterning of the anteroposterior axis.” 2005. Doctoral Dissertation, Universiteit Utrecht. Accessed November 20, 2019. http://dspace.library.uu.nl:8080/handle/1874/7295.

MLA Handbook (7th Edition):

Peres, João Nuno Borges Baptista. “Divide and conquer: Segmentation and patterning of the anteroposterior axis.” 2005. Web. 20 Nov 2019.

Vancouver:

Peres JNBB. Divide and conquer: Segmentation and patterning of the anteroposterior axis. [Internet] [Doctoral dissertation]. Universiteit Utrecht; 2005. [cited 2019 Nov 20]. Available from: http://dspace.library.uu.nl:8080/handle/1874/7295.

Council of Science Editors:

Peres JNBB. Divide and conquer: Segmentation and patterning of the anteroposterior axis. [Doctoral Dissertation]. Universiteit Utrecht; 2005. Available from: http://dspace.library.uu.nl:8080/handle/1874/7295

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