Sweetpotato-based complementary food would be less inhibitory on mineral absorption than a maize-based infant food assessed by compositional analysis.

The availability of micronutrients from sweetpotato-based complementary foods (CFs): oven-toasted and roller-dried ComFa, and from a maize-based infant food, enriched Weanimix, was compared using phytate/mineral molar ratios, polyphenols and ß-carotene levels. The phytate/calcium, iron and zinc molar ratios of approximately 0.17, 1 and 15 predict better absorption of calcium, iron and zinc respectively. Generally, the sweetpotato-based CFs had at least half the phytate/mineral ratios of enriched Weanimix. The phytate/iron ratio in both the sweetpotato- and the maize-based CFs was greater than 1. Only the ComFa formulations had phytate/zinc ratio lower than 15. The level of polyphenol (iron inhibitor) was similar for the formulations. Only the sweetpotato-based CFs contained measurable levels of ß-carotene, a possible iron enhancer. The lower phytate/mineral ratios and the ß-carotene level of the sweetpotato-based CFs suggest that calcium, iron and zinc absorption could be better from them than from the maize-based infant food.

Receptor tyrosine kinase ErbB4 modulates neuroblast migration and placement in the adult forebrain.

Neural progenitor proliferation, differentiation and migration are continually active in the rostral migratory stream of the adult brain. Here, we show that the receptor tyrosine kinase ErbB4 is expressed prominently by the neuroblasts present in the subventricular zone and the rostral migratory stream. The neuregulins (NRG1-NRG3), which have been identified as ErbB4 ligands, are detected either in the stream or in adjacent regions. Mice deficient in ErbB4 expressed under the control of either the nestin or the hGFAP promoter have altered neuroblast chain organization and migration and deficits in the placement and differentiation of olfactory interneurons. These findings suggest that ErbB4 activation helps to regulate the organization of neural chains that form the rostral migratory stream and influences the differentiation of olfactory interneuronal precursors.

Neuregulin-2 is synthesized by motor neurons and terminal Schwann cells and activates acetylcholine receptor transcription in muscle cells expressing ErbB4.

Acetylcholine receptor (AChR) genes are transcribed selectively in synaptic nuclei of skeletal muscle fibers, leading to accumulation of the mRNAs encoding AChR subunits at synaptic sites. The signals that regulate synapse-specific transcription remain elusive, though Neuregulin-1 is considered a favored candidate. Here, we show that motor neurons and terminal Schwann cells express neuregulin-2, a neuregulin-1-related gene. In skeletal muscle, Neuregulin-2 protein is concentrated at synaptic sites, where it accumulates adjacent to terminal Schwann cells. Neuregulin-2 stimulates AChR transcription in cultured myotubes expressing ErbB4, as well as ErbB3 and ErbB2, but not in myotubes expressing only ErbB3 and ErbB2. Thus, Neuregulin-2 is a candidate for a signal that regulates synaptic differentiation.