Voltage-dependent calcium influx has been shown to regulate the differentiation of cultured amphibian spinal neurons. We have examined the transient elevation of intracellular calcium induced by depolarization, using calcium indicators and confocal microscopy with high temporal and spatial resolution. Rapid calcium elevations in both the nucleus and the cytosol are primarily due to calcium-dependent release of calcium from intracellular stores. Depletion of stores associated with the endoplasmic reticulum reduces all transients. Elevations diminish with neuronal maturation. Depletion of stores of intracellular calcium at early times affects neuronal differentiation in a manner similar to the prevention of influx. The results indicate that both influx and release are necessary to promote neuronal differentiation.
Functional regulation of potassium currents in developing neurons is pivotal for changes in excitability and action potential waveform. Here, we test whether an excess of potassium channel transcripts is sufficient to drive functional expression of potassium current and shortening of the duration of the action potential. Injection of Shaker-like potassium channel transcripts into two-cell stage embryos achieves increases in RNA levels. The elevated levels of potassium channel RNA produce larger delayed-rectifier currents. Action potential durations are briefer, indicating that larger potassium currents are not compensated by changes in inward currents. Strikingly, overexpression of potassium current RNA leads to a reduction in the number of morphologically differentiated neurons in culture. We suggest that, by prematurely reducing the duration of the impulse, early overexpression of potassium channel activity suppresses normal developmental cues.
This paper examines the impact of ination on economic growth in Sub-Saharan Africa in order to provide an empirical evidence whether ination hinders or boost economic activities in the region. The paper found that ination exhibits a reducing-growth effect in both short-term and long-term periods using Panel Autoregressive Distributed Lag (PARDL) model. Therefore, the study recommends that African government needs to address the issues of ination especially imported ination in order to stimulate sustainable economic growth in the region. In addition, strengthening political commitment to ensure conducive business environment has to be paramount rather than depending on the traditional model of bring your own infrastructure. Keywords: Ination, Sub-Sahara Africa, Panel Autoregressive Distributed Lag