The formation of the embryonic brain and spinal cord begins as the neural plate bends to form the neural folds, which meet and fuse to close the neural tube. The neural ectoderm and surrounding tissues also coordinate proliferation, differentiation, and patterning. This highly orchestrated process is susceptible to disruption, leading to neural tube defects (NTDs), a common birth defect. Here, we highlight genetic and epigenetic contributions to neural tube closure. We describe an online database we created as a resource for researchers, geneticists, and clinicians. Neural tube closure is sensitive to environmental influences, and we discuss disruptive causes, preventative measures, and possible mechanisms. New technologies will move beyond candidate genes in small cohort studies toward unbiased discoveries in sporadic NTD cases. This will uncover the genetic complexity of NTDs and critical gene-gene interactions. Animal models can reveal the causative nature of genetic variants, the genetic interrelationships, and the mechanisms underlying environmental influences.

Intramolecular hydroamination of aminoallenes is catalyzed by titanium complexes with a number of chiral amino alcohols. The ring-closing reaction of hepta-4,5-dienylamine at 110 °C with 5 mol % catalyst gives a mixture of 6-ethyl-2,3,4,5-tetrahydropyridine (14-33%) and both Z-and E-2-propenylpyrrolidine (67-86%). However, the ring-closing reaction of 6-methylhepta-4,5-dienylamine at 135 °C with 5 mol % catalyst gives exclusively 2-(2methylpropenyl)pyrrolidine. The pyrrolidine products are obtained with enantiomeric excesses up to 16%.

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Experiments were carried out to examine the effects of nitrogen source on nitrogen incorporation into cyanophycin during nitrogen limitation and repletion, both with or without inhibition of protein synthesis, in cyanobacteria grown on either nitrate or ammonium. The use of nitrate and ammonium, 14 N labeled in the growth medium and 15 N labeled in the repletion medium, allows the determination of the source of nitrogen in cyanophycin using proton nuclear magnetic resonance spectroscopy. The data suggest that nitrogen from both the breakdown of cellular protein ( 14 N) and directly from the medium ( 15 N) is incorporated into cyanophycin. Nitrogen is incorporated into cyanophycin at different rates and to different extents, depending on the source of nitrogen (ammonium or nitrate) and whether the cells are first starved for nitrogen. These differences appear to be related to the activity of nitrate reductase in cells and to the possible expression of cyanophycin synthetase during nitrogen starvation.