Migratory Neural Crest Cells Phagocytose Dead Cells in the Developing Nervous System

During neural tube closure and spinal cord development, many cells die in both the central and peripheral nervous systems (CNS and PNS, respectively). However, myeloid-derived professional phagocytes have not yet colonized the trunk region during early neurogenesis. How apoptotic cells are removed from this region during these stages remains largely unknown. Using live imaging in zebrafish, we demonstrate that neural crest cells (NCCs) respond rapidly to dying cells and phagocytose cellular debris around the neural tube. Additionally, NCCs have the ability to enter the CNS through motor exit point transition zones and clear debris in the spinal cord. Surprisingly, NCCs phagocytosis mechanistically resembles macrophage phagocytosis and their recruitment toward cellular debris is mediated by interleukin-1β. Taken together, our results reveal a role for NCCs in phagocytosis of debris in the developing nervous system before the presence of professional phagocytes.

Multidimensional liquid chromatography of opioid peptides: fluorogenic labelling, retention prediction and separation optimization

The ultra-trace analysis of opioid peptides in biological samples can be achieved by multidimensional liquid chromatography with pre-column fluorogenic derivatization with naphthalene-2,3-dicarboxaldehyde in the presence of cyanide ion. However, in order to take full advantage of the high sensitivity possible with detectors based on laser-induced fluorescence or chemiluminescence, each component of the analytical method must be carefully optimized. In this study, strategies are presented for the prediction of retention time and the optimization of separations of derivatized opioid peptides in multidimensional LC systems.

Determination of immunoglobulins in blood serum by high-performance affinity chromatography

High-performance affinity chromatography columns were prepared by immobilizing protein A from Staphylococcus aureus on 10-microns diol-bonded silica. Immunoglobulin-containing samples were injected into the column at pH 7 and eluted by stepwise changes to pH 3. Immunoglobulin G, A, and M standards were tested, but only a small fraction of the latter two was retained on the column. Analysis of 3-microliters samples of reference blood sera without pretreatment was performed using immunoglobulin G standards. Good agreement was observed between the immunoglobulin G concentrations measured by this method and by radial immunodiffusion. Chromatography of albumin and electrophoresis of retained serum fractions showed no interference by non-specific adsorption. Chromatographic analysis times were 4 min or less.