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Atrazine delays Purkinje cell development in vitro as evidenced by Golgi method in primary organotypic cultures of mouse cerebellar cortex
858
Poster Session 1 Abstracts 2 June 2008 / Int. J. Devl Neuroscience 26 (2008) 841–866
should be done in order to elucidate the significance of the expression.
[P1.51]
Acknowledgement
M. Tamura 1,*, S. Nakahara 1, A. Kakita 2, N. Matsuki 1, R. Koyama 1
This study was supported by the Major State Basic Research Development Program of China (973 Program, NO.2003CB515300)
1
doi: 10.1016/j.ijdevneu.2008.09.099 [P1.50] Atrazine delays Purkinje cell development in vitro as evidenced by Golgi method in primary organotypic cultures of mouse cerebellar cortex ˜ a-Contreras *, D. Davila-Vera, R.V. Mendoza-Bricen ˜o Z. Pen University of Los Andes, Venezuela *Corresponding author. Keywords: Purkinje cell development; Primary organotypic cultures; Atrazine; Mouse cerebellar cortex
There is limited information on neurotoxic effects of atrazine in developing nervous system. Atrazine, an extensively used chloros-triazine herbicide, has been identified as an endocrine disruptor in amphibians. Considering the importance of endocrine influence for normal brain development, in this study we examined the effects of atrazine on the development of Purkinje cells (PC) in vitro, by employing the Golgi method to study the morphological changes that occur during PC differentiation. Primary organotypic cultures of mouse cerebellar cortex were prepared from recently born Mus musculus mice (P0) and at postnatal days 3 (P3), P5, P7 and P9. Explanted cerebellar cortices from each age were divided into two groups: control and atrazine-exposed. A dosis of 15 mg atrazine/kg wet weight was added into the incubation medium every 48 h during the 6 day-period of incubation. Cultured tissues were harvested, fixed and stained using a modified Golgi method5 and then observed under Polyvar high resolution light microscopy. After 6 days of incubation, PC from control cultures obtained from mice at P0 until P9 showed a normal sequence of development in vitro. Immature morphological characteristics of PC were observed in P0 cultures, such as cell bodies that are highly irregular in shape and the presence of numerous prolongations from their soma. Cultures obtained at P3 showed PC with few cellular prolongations and cell body of more regular shape. At this stage, the emergence of PC primary dendrite and initial segment of the axon can already be observed. Cultures from P5 and P7 animals showed more developed axons and dendritic trees with secondary dendrite ramifications. In P9 cerebellar cultures, the PCs demonstrated phenotypic characteristics as in situ mature PCs. On the other hand, administration of atrazine during incubation not only delayed the development of PCs but also hindered the acquirement of mature phenotypic characteristics. Atrazine-exposed cultures from P0 until P3 showed highly immature PCs and it was not until P5 that the emergence of the primary dendrite and axon initial segment was observed. These results demonstrate the endocrinedisrupting effects of atrazine in the developing nervous system. doi: 10.1016/j.ijdevneu.2008.09.100
Sex differences in dendritic maturation of hippocampal granule cells after prenatal stress
The University of Tokyo, Japan University of Niigata, Japan *Corresponding author. 2
Keywords: Glucocorticoid; Neurogenesis; Antidepressant; Time-lapse imaging
Exposure of pregnant mothers to stress increases the risk of depressive disorders in their offspring later in life. However, cellular and molecular mechanisms underlying the phenomena are not clear. Here, we investigated the effect of antenatal stress on the morphological maturation of dentate granule cells in the hippocampus, which is strongly involved in the development of depressive disorders. Pregnant rats were subjected daily to three sessions of 45 min of restraint stress from day 15 to 21 of gestation, and subsequently hippocampal slices were prepared from their offspring at postnatal day 0–1 and cultured. After 14 days in vitro, the branch number and the total length of granule cell dendrites, which were visualized by biocytin injection, significantly decreased compared with control. Importantly, the effect was more remarkable in female than in male. This is the first study that reveals the sex differences in the prenatal stressinduced suppression of dendritic maturation of granule cells. doi: 10.1016/j.ijdevneu.2008.09.101 [P1.52] IgCAMs redundantly control different aspects of axon guidance in C. elegans V. Schwarz 1, J. Pan 2, S. Voltmer-Irsch 1, H. Hutter 2,* 1
Max Planck Institute for Medical Research, Germany Simon Fraser University, Canada *Corresponding author. 2
Keywords: IgCAM; Axon guidance; C. elegans
Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) form one of the largest and oldest families of adhesion molecules and receptors with a role in neuronal development. We systematically analyzed previously uncharacterized members of this family in C. elegans. Expression studies of 12 IgCAMs revealed that most of them are expressed in the nervous system. However, expression for none of these genes is confined to a single tissue and all tissues express at least one of the IgCAMs. Neuronal expression was analyzed at the single cell level. Significant overlap in expression was found in central components of the motor circuit like command interneurons and ventral cord motoneurons as well as motoneurons innervating head muscles. Sensory neurons are underrepresented among the cells expressing these IgCAMs. Mutations were obtained for eight genes showing significant neuronal expression. Phenotypic analysis of single mutants revealed only limited axonal defects in neurons belonging to the motor circuit in a few of the mutants. The majority of the mutants had no apparent defects in the neurons studied. Systematic genetic interaction studies identified two sets of interactions affecting interneuron navigation and commissure outgrowth. A quadruple mutant of rig-1, rig-3, rig-5 and rig-6 show significant interneuron navigation defects. None of the four possible triple mutant combinations shows significant defects, indicating that all four genes act redundantly to guide interneuron axons. Similarly, significant defects in motoneuron commissure outgrowth are apparent only in a triple mutant combination of syg-1, wrk-1 and
Poster Session 1 Abstracts 2 June 2008 / Int. J. Devl Neuroscience 26 (2008) 841–866
should be done in order to elucidate the significance of the expression.
[P1.51]
Acknowledgement
M. Tamura 1,*, S. Nakahara 1, A. Kakita 2, N. Matsuki 1, R. Koyama 1
This study was supported by the Major State Basic Research Development Program of China (973 Program, NO.2003CB515300)
1
doi: 10.1016/j.ijdevneu.2008.09.099 [P1.50] Atrazine delays Purkinje cell development in vitro as evidenced by Golgi method in primary organotypic cultures of mouse cerebellar cortex ˜ a-Contreras *, D. Davila-Vera, R.V. Mendoza-Bricen ˜o Z. Pen University of Los Andes, Venezuela *Corresponding author. Keywords: Purkinje cell development; Primary organotypic cultures; Atrazine; Mouse cerebellar cortex
There is limited information on neurotoxic effects of atrazine in developing nervous system. Atrazine, an extensively used chloros-triazine herbicide, has been identified as an endocrine disruptor in amphibians. Considering the importance of endocrine influence for normal brain development, in this study we examined the effects of atrazine on the development of Purkinje cells (PC) in vitro, by employing the Golgi method to study the morphological changes that occur during PC differentiation. Primary organotypic cultures of mouse cerebellar cortex were prepared from recently born Mus musculus mice (P0) and at postnatal days 3 (P3), P5, P7 and P9. Explanted cerebellar cortices from each age were divided into two groups: control and atrazine-exposed. A dosis of 15 mg atrazine/kg wet weight was added into the incubation medium every 48 h during the 6 day-period of incubation. Cultured tissues were harvested, fixed and stained using a modified Golgi method5 and then observed under Polyvar high resolution light microscopy. After 6 days of incubation, PC from control cultures obtained from mice at P0 until P9 showed a normal sequence of development in vitro. Immature morphological characteristics of PC were observed in P0 cultures, such as cell bodies that are highly irregular in shape and the presence of numerous prolongations from their soma. Cultures obtained at P3 showed PC with few cellular prolongations and cell body of more regular shape. At this stage, the emergence of PC primary dendrite and initial segment of the axon can already be observed. Cultures from P5 and P7 animals showed more developed axons and dendritic trees with secondary dendrite ramifications. In P9 cerebellar cultures, the PCs demonstrated phenotypic characteristics as in situ mature PCs. On the other hand, administration of atrazine during incubation not only delayed the development of PCs but also hindered the acquirement of mature phenotypic characteristics. Atrazine-exposed cultures from P0 until P3 showed highly immature PCs and it was not until P5 that the emergence of the primary dendrite and axon initial segment was observed. These results demonstrate the endocrinedisrupting effects of atrazine in the developing nervous system. doi: 10.1016/j.ijdevneu.2008.09.100
Sex differences in dendritic maturation of hippocampal granule cells after prenatal stress
The University of Tokyo, Japan University of Niigata, Japan *Corresponding author. 2
Keywords: Glucocorticoid; Neurogenesis; Antidepressant; Time-lapse imaging
Exposure of pregnant mothers to stress increases the risk of depressive disorders in their offspring later in life. However, cellular and molecular mechanisms underlying the phenomena are not clear. Here, we investigated the effect of antenatal stress on the morphological maturation of dentate granule cells in the hippocampus, which is strongly involved in the development of depressive disorders. Pregnant rats were subjected daily to three sessions of 45 min of restraint stress from day 15 to 21 of gestation, and subsequently hippocampal slices were prepared from their offspring at postnatal day 0–1 and cultured. After 14 days in vitro, the branch number and the total length of granule cell dendrites, which were visualized by biocytin injection, significantly decreased compared with control. Importantly, the effect was more remarkable in female than in male. This is the first study that reveals the sex differences in the prenatal stressinduced suppression of dendritic maturation of granule cells. doi: 10.1016/j.ijdevneu.2008.09.101 [P1.52] IgCAMs redundantly control different aspects of axon guidance in C. elegans V. Schwarz 1, J. Pan 2, S. Voltmer-Irsch 1, H. Hutter 2,* 1
Max Planck Institute for Medical Research, Germany Simon Fraser University, Canada *Corresponding author. 2
Keywords: IgCAM; Axon guidance; C. elegans
Cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) form one of the largest and oldest families of adhesion molecules and receptors with a role in neuronal development. We systematically analyzed previously uncharacterized members of this family in C. elegans. Expression studies of 12 IgCAMs revealed that most of them are expressed in the nervous system. However, expression for none of these genes is confined to a single tissue and all tissues express at least one of the IgCAMs. Neuronal expression was analyzed at the single cell level. Significant overlap in expression was found in central components of the motor circuit like command interneurons and ventral cord motoneurons as well as motoneurons innervating head muscles. Sensory neurons are underrepresented among the cells expressing these IgCAMs. Mutations were obtained for eight genes showing significant neuronal expression. Phenotypic analysis of single mutants revealed only limited axonal defects in neurons belonging to the motor circuit in a few of the mutants. The majority of the mutants had no apparent defects in the neurons studied. Systematic genetic interaction studies identified two sets of interactions affecting interneuron navigation and commissure outgrowth. A quadruple mutant of rig-1, rig-3, rig-5 and rig-6 show significant interneuron navigation defects. None of the four possible triple mutant combinations shows significant defects, indicating that all four genes act redundantly to guide interneuron axons. Similarly, significant defects in motoneuron commissure outgrowth are apparent only in a triple mutant combination of syg-1, wrk-1 and