Monoclonal antibodies (mAbs) to rat neurofilament (NF) proteins NF-L, NF-M, and NF-H were used to examine the developmental programs of NF expression in rat embryos. The ability of these mAbs to recognize differentially phosphorylated states of NF-M and NF-H (Lee et al., 1987, the preceding paper) was exploited in order to examine the temporal and spatial patterns of NF phosphorylation during early neuronal development in vivo. NF proteins were first detected on the twelfth day postfertilization (E12) using NF-L- or NF-M-specific mAbs. By E13, the coexpression of NF-L and NF-M was widespread, reflecting dramatic increases of immunoreactivity to both subunits. Partial phosphorylation, denoted P[+], of NF-M was already present in perikarya and neurites of E12 neurons. Extensively phosphorylated, or P[+++], isoforms of NF-M appeared in E13 axons, thereby establishing a proximodistal gradient of NF phosphorylation during the earliest phase of NF expression. Immunoblots of tissue homogenates revealed that most NF-M of E13 embryos exists in a partially phosphorylated, or P[+], isoform. Unequivocal staining for NF-H first appeared at E15, a time at which NF-L and NF-M had already attained their adult patterns of immunocytochemical staining. Levels of NF-H were extremely low at E15 but could be detected in all of its differentially phosphorylated states, i.e., nonphosphorylated P[-], partly P[+], and highly P[+++] phosphorylated isoforms. P[+++] isoforms of NF-H were restricted to the distal portions of E15 axons, although staining of more proximal axons, like those in adult, was noted by E17. Immunoblots of E17 embryos revealed most NF-H as P[-] and P[+] isoforms. Quantities of immunoreactive NF-H increased very slowly and remained well below those of NF-M and NF-L for several weeks beyond birth. These results show that sequential forms of NFs are expressed by developing and maturing neurons throughout the nervous system. An "immature" form of NFs, composed of NF-M and NF-L, appears to function in establishing the neuronal phenotype and in initiating and maintaining neurite outgrowth. Addition of NF-H confers a "mature" state to the NF. This delayed expression of NF-H is a slow and graduated process that coincides in time with the stabilization of neuronal circuitries and may be important in modulating axonal events, such as the slowing of cytoskeletal transport and the growth of axonal caliber.

Two-stage expression of neurofilament polypeptides during rat neurogenesis with early establishment of adult phosphorylation patterns

The appearance of neurofilaments (NFs) and vimentin (Vim) in the nervous system of the mouse embryo was documented using immunohistochemical techniques. The three NF protein subunits appear early and simultaneously in central and peripheral neurons at 9 to 10 days of gestation. The onset of NF expression is concomitant with axon elongation and correlates extremely well with neurofibrillar differentiation and, in the case of autonomic ganglia, with the expression of adrenergic neurotransmitter properties. In the central and peripheral nervous system, NF expression is preceded by that of Vim, and both types of intermediate filaments coexist within the same cell for a short period of time.

https://www.jneurosci.org/content/jneuro/4/8/2080.full.pdf

Initial expression of neurofilaments and vimentin in the central and peripheral nervous system of the mouse embryo in vivo.

The nature of Lewy bodies (LBs) in the brain stem and cerebral cortex in five cases of diffuse Lewy body disease and one case of Parkinson's disease with dementia were investigated immunocytochemically with various antibodies to cytoskeletal proteins, paired helical filaments (PHF) and ubiquitin. Antibodies to 200-kDa component of neurofilament, tau and PHF showed no significant reactions with most of LBs. Antibodies to high-molecular weight microtubule-associated proteins (HMWMAPs) moderately stained the periphery of a few of LBs. A monoclonal antibody to PHF (DF2) which recognizes ubiquitin, and polyclonal antibodies to ubiquitin immunostained virtually all of the typical and cortical LBs as intensely as Alzheimer's neurofibrillary tangles and senile plaque neurites: the periphery of LBs was darkly stained, whereas the central core of typical LBs and central zone of cortical LBs were less intensely stained or remained unstained. Immunoelectron microscopy of the LBs with DF2 revealed that immune reaction products were located on the filaments exclusively in the periphery of LBs, but not on those in the center. These findings suggest that both types of LBs are immunocytochemically indistinguishable despite some structural differences, and that peripherally located filaments in LBs are tagged with ubiquitin, an element required for the ATP-dependent proteolysis system in the cell. Antibodies to ubiquitin are the most useful marker of LBs ever known.

Lewy bodies are ubiquitinated. A light and electron microscopic immunocytochemical study.

The use of silver for detection of protein in polyacrylamide gels is becoming widespread. An effort has been made to develop a silver stain which minimizes the time to perform the stain, the amount of silver used, and the complexity of the procedures, and which maximizes the sensitivity. This stain is almost 200-fold more sensitive than the Coomassie Brilliant Blue R-250 stain. This silver stain procedure has been shown, with eight purified proteins, to generally be linear over a 40-fold range in concentration, between 0.005 ng/mm2 to 2.0 ng/mm2. For greater sensitivity, a recycling procedure has been developed. This procedure is capable of amplifying trace proteins which could not be visualized with previous silver stain techniques. Analysis of the kinetics of image development revealed that the silver ion was the limiting factor in image formation. By recycling the gel through silver nitrate solutions, silver ions are replenished in the gel, permitting amplification of further details when the gel is treated with a developing solution. A number of problems inherent in silver stain detection of proteins in polyacrylamide gels are discussed with suggested remedies.

Simplified silver protein detection and image enhancement methods in polyacrylamide gels

Gel protein stains: silver stain.

Bodian's silver method was used to stain polypeptides of rat spinal cord or peripheral nerve separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The bands corresponding to the t...

https://science.sciencemag.org/content/sci/213/4515/1521.full.pdf

L Autilio Gambetti

Papers

Bodian's silver method stains neurofilament polypeptides