The secreted signal retinoic acid (RA) has been shown to control multiple, sequential steps of motor neuron differentiation in the ventral spinal cord, including initial patterning of progenitors cells and specification of motor neuron subtype identity [11].
Another recent report demonstrates that Neurog2 phosphorylation at Ser231 and Ser234 by GSK3 regulates the specification of motor neuron subtypes but has no effect on the total number of neurons produced per se [38].
Previously, Lim3 was found to be active in the Drosophila embryonic nervous system and to take part in regulatory networks leading to the specification of motor neuron subclass identity, axon pathfinding, and finally, proper muscle innervation [12].
Gene expression changes in the anterior hindbrain are extensive (see below), suggesting that specification of motor as well as sensory components of CN V and VII might be compromised.
The second trend followed from a seminal discovery made by Jessell and co-workers [ 12] on the specification of motor neurons and other neurons in developing mouse spinal cord.
There are 12 LIM-HD-containing genes in vertebrates (Fig. 6A), and most of them are involved in neural development, such as specification of motor neuron subtypes (Hobert and Westphal, 2000; Jessell, 2000).
Genes of the olig family (olig1, olig2, and olig3) have key roles in the specification of motor neurons, dorsal interneurons, and oligodendrocytes in the vertebrate CNS [ 18, 23, 24, 28- 30].
This result implies that Fz3 is not required for the initial specification of LMCL motor neurons.
If these two components reflect the activation of dorsal prefrontal and posterior areas involved in the programming of reaching movements, as suggested above, their simultaneous presence might indicate that these areas work in parallel, rather than sequentially, during the specification of a motor program (see also Naranjo et al., 2007).
The specifications of the motor bike are as follows: No. of strokes: four.
The torque requirements of the driven equipment determine the torque specifications of the motor from initial start to shutdown.
