| 1. |
- Pattyn, A, et al.
(författare)
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Complementary roles for Nkx6 and Nkx2 class proteins in the establishment of motoneuron identity in the hindbrain
- 2003
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 130:17, s. 4149-4159
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Tidskriftsartikel (refereegranskat)abstract
- The genetic program that underlies the generation of visceral motoneurons in the developing hindbrain remains poorly defined. We have examined the role of Nkx6 and Nkx2 class homeodomain proteins in this process, and provide evidence that these proteins mediate complementary roles in the specification of visceral motoneuron fate. The expression of Nkx2.2 in hindbrain progenitor cells is sufficient to mediate the activation of Phox2b, a homeodomain protein required for the generation of hindbrain visceral motoneurons. The redundant activities of Nkx6.1 and Nkx6.2, in turn, are dispensable for visceral motoneuron generation but are necessary to prevent these cells from adopting a parallel program of interneuron differentiation. The expression of Nkx6.1 and Nkx6.2 is further maintained in differentiating visceral motoneurons, and consistent with this the migration and axonal projection properties of visceral motoneurons are impaired in mice lacking Nkx6.1 and/or Nkx6.2 function. Our analysis provides insight also into the role of Nkx6 proteins in the generation of somatic motoneurons. Studies in the spinal cord have shown that Nkx6.1 and Nkx6.2 are required for the generation of somatic motoneurons,and that the loss of motoneurons at this level correlates with the extinguished expression of the motoneuron determinant Olig2. Unexpectedly, we find that the initial expression of Olig2 is left intact in the caudal hindbrain of Nkx6.1/Nkx6.2 compound mutants, and despite this, all somatic motoneurons are missing. These data argue against models in which Nkx6 proteins and Olig2 operate in a linear pathway, and instead indicate a parallel requirement for these proteins in the progression of somatic motoneuron differentiation. Thus, both visceraland somatic motoneuron differentiation appear to rely on the combined activity of cell intrinsic determinants, rather than on a single key determinant of neuronal cell fate.
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| 2. |
- Pattyn, A, et al.
(författare)
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Coordinated temporal and spatial control of motor neuron and serotonergic neuron generation from a common pool of CNS progenitors
- 2003
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Ingår i: Genes & development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 17:6, s. 729-737
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Tidskriftsartikel (refereegranskat)abstract
- Neural progenitor cells often produce distinct types of neurons in a specific order, but the determinants that control the sequential generation of distinct neuronal subclasses in the vertebrate CNS remain poorly defined. We examined the sequential generation of visceral motor neurons and serotonergic neurons from a common pool of neural progenitors located in the ventral hindbrain. We found that the temporal specification of these neurons varies along the anterior-posterior axis of the hindbrain, and that the timing of their generation critically depends on the integrated activities of Nkx- and Hox-class homeodomain proteins. A primary function of these proteins is to coordinate the spatial and temporal activation of the homeodomain protein Phox2b, which in turn acts as a binary switch in the selection of motor neuron or serotonergic neuronal fate. These findings assign new roles for Nkx, Hox, and Phox2 proteins in the control of temporal neuronal fate determination, and link spatial and temporal patterning of CNS neuronal fates.
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| 3. |
- Cerecetto, H, et al.
(författare)
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Synthesis and herbicidal activity of N-oxide derivatives
- 2000
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 48:7, s. 2995-3002
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Tidskriftsartikel (refereegranskat)abstract
- As part of an ongoing program on the chemistry and biological activity of N-oxide-containing molecules, a number of novel 1,2,5-oxadiazole N-oxide, benzo[1,2-c]1,2,5-oxadiazole N-oxide, and quinoxaline N,N'-dioxide derivatives were synthesized and evaluated for their herbicidal activity. Many of these compounds exhibited moderate to good herbicidal pre-emergence activity against Triticum aestivum. Dose-response studies were done on the more representative compounds (12, 20, and 26). The most active compound, butylcarbamoylbenzo[1,2-c]l,2,5-oxadiazole N-oxide, 26, displayed herbicidal activity at concentrations as low as 24 g/ha.
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