Neural tube development

Shimamura, K., Hartigan, D.J., Martinez, S., Puelles, L., and Rub-enstein, J.L.R (1995) Longitudinal organization of the anterior neural plate an d neural tube. Development 121 3923—3933. 

Marasas, W. F., Riley, R. T., Hendricks, K. A., Stevens, V. L., Sadler, T. W., Gelineau-van Waes, J., Missmer, S. A., Cabrera, J., Torres, O., Gelderblom, W. C., Allegood, J., Martinez, C., et al. (2004). Fumonisins disrupt sphingolipid metabolism, folate transport, and neural tube development in embryo culture and in vivo A potential risk factor for human neural tube defects among populations consuming fumonisin-contaminated maize. J. Nutr. 134(4), 711-716. 

The teratogenic syndrome of in utero VPA exposure in humans includes neural, craniofacial, cardiovascular, and skeletal defects. A similar teratology is exhibited in rodents, rabbits, and nonhuman primates. The most dramatic of malformations associated with gestational VPA exposure is spina bifida, a neural tube defect that is estimated to occur in 1-2% of VPA exposed infants. Mice are the only known animal model to exhibit a comparable effect of VPA on neural tube development. 

The mechanisms by which VPA disrupts neural tube development remain largely unknown. Neural tube closure during organogenesis requires continuous cell proliferation of the neuroepithelia, and in vitro studies indicate that VPA causes cell cycle arrest in neuronal cells. These findings suggest that VPA either directly disturbs the proliferative ability of neuronal cells or perhaps alters their sensitivity to neurotrophic growth factors. 

The answer is a. (Murray, pp 812-828. Scriver, pp 3-45. Sack, pp 167-180. Wilson, pp 287-324.) Spina bifida is a defect of neural tube development that can be partially prevented by encouraging preconceptional folic acid supplementation in women desiring to become pregnant. Examination for subtle evidence of dysmorphology in children with major birth defects is necessary to rule out a syndrome. Syndromes often exhibit Mendelian or chromosomal inheritance. 

Liu, J.P., Jessell, T.M. 1998. A role for rhoB in the delamination of neural crest cells from the dorsal neural tube. Development 125, 5055-5067. 

Mice (Mus sp.) fed a zinc-deficient diet of 0.7 mg Zn/kg ration for 40 days, when compared to mice fed a zinc-adequate diet of 36.5 mg Zn/kg, had a reduced growth rate, impaired phagocytic function, increased susceptibility to lead poisoning, and reduced zinc content in blood (0.7mg/L vs. 1.0-1.1) and liver (12.0 mg Zn/kg EW vs. 17.0-19.0). Zinc deficiency during early development affects neural tube development through arrested cell... 

Takeuchi, T, Yamazaki, Y, Katoh-Fuki, Y, Tsuchiya, R., Kondo, S., Motoyama, J., and Higashinakagawa, T. (1995) Gene trap capture of a novel mouse gene jumonji, required for neural tube development. Genes Dev. 9,1211-1222. 

Sharman, A.C., Shimeld, S.M. and Holland, P.W.H. (1999) An amphioxus Msx gene expressed predominantly in the dorsal neural tube . Development Genes and Evolution, 209, 260-3. 

Folate supplementation is often given in pregnancy where its deficiency can lead to birth defects resulting from defects in neural tube development such as spina bifida. 

Neural tube defects Birth defect resulting from improper development of the central nervous system. 

Epstein, D. J., Vekemans, M., and Gros, P. (1991). Splotch, a mutation affecting development of the mouse neural tube, shows a deletion within the paired homeodomain of Pax-3. Cell 67 767-774. 

The best examples of pleiotropy have been provided by developmental biologists. Two examples illustrate the pleiotropic action of developmental genes. Sonic hedgehog participates in the formation of the different cell types that form the neural tube, in limb development and in somitogenesis, a process by which mesodermic cells aggregate to form bones and muscles. 

Cell adhesion molecules (CAMs) play critical roles in all facets of nervous system development and maintenance. Important phenomena in which CAMs are involved include initial formation of the neural tube and the neural crest, migration of all neurons and glial cells, axonal outgrowth and guidance, target selection, synaptic stabilization and plasticity, myelination and nerve regeneration after injury (see Chs 4,24,28-30 and 53). Adhesion molecules interact with each other and with nonadhesive cell-surface and/or cytoplasmic molecules, and, in the two... 

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