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H Rohrer

Publications and source records attributed to H Rohrer.

At least 73 records · Page 4Linked to original sources
PubMed1985

Progenitor cells from embryonic chick dorsal root ganglia differentiate in vitro to neurons: biochemical and electrophysiological evidence.

We have analyzed the appearance of neurons and glial cells in chick dorsal root ganglia during development. Neurons were identified by the presence of polysialogangliosides recognized by tetanus toxin (GD1b, GT1) or by the monoclonal antibody Q211 directed against polysialogangliosides containing four, five and six sialic acid residues. Glial cells were identified by the presence of 04 antigen. A population of undifferentiated cells, i.e., cells which express neither neuronal nor glial cell surface antigens, present in dorsal root ganglia until embryonic day 7, was separated from the neuronal and glial population. This cell population contains neuronal progenitor cells which differentiate to neurons within 1 day in culture. This differentiation process is characterized by the appearance of neuronal morphology, of neuron-specific gangliosides and by the appearance of voltage-dependent sodium and calcium channels.

Animals↗
PubMed1985

Placodal sensory neurons in culture: nodose ganglion neurons are unresponsive to NGF, lack NGF receptors but are supported by a liver-derived neurotrophic factor.

Explant and dissociated neuron-enriched cultures of nodose ganglia (inferior or distal sensory ganglion of the Xth cranial nerve) were established from chick embryos taken between embryonic Day 4 (E4) and Day 16 (E16). The response of each type of culture to nerve growth factor (NGF) was examined over this developmental range. At the earliest ages taken (E4-E6), NGF elicited modest neurite outgrowth from ganglion explants cultured in collagen gel for 24 hr, although the effect of NGF on ganglia taken from E4 chicks was only marginally greater than spontaneous neurite extension from control ganglia of the same developmental age. The response of nodose explants to NGF was maximal at E6-E7, but declined to a negligible level in ganglia taken from E9-E10 or older chick embryos. In dissociated neuron-enriched cultures, nodose ganglion neurons were unresponsive to NGF throughtout the entire developmental age range between E5 and E12. In contrast to the lack of effect of NGF, up to 50% of nodose ganglion neurons survived and produced extensive neurites in dissociated cultures, on either collagen- or polylysine-coated substrates, in the presence of extracts of late embryonic or early posthatched chick liver (E18-P7). Antiserum to mouse NGF did not block the neurotrophic activity of chick (or rat or bovine) liver extracts. Whether cultured with chick liver extract alone or with chick liver extract plus NGF, nodose ganglion neurons taken from E6-E12 chick embryos and maintained in culture for 2 days were devoid of NGF receptors, as assessed by autoradiography of cultures incubated with 125I-NGF. Under similar conditions 70-95% of spinal sensory neurons (dorsal root ganglion--DRG) were heavily labeled. 2+

Animals↗
PubMed1985

Differences and similarities in the neurotrophic growth factor requirements of sensory neurons derived from neural crest and neural placode.

This article reviews recent studies that have examined differences and similarities in the neurotrophic growth factor requirements of neural crest- and neural placode-derived sensory neurons of the developing chick embryo. From in vitro experiments using both explant and dissociated, neuron-enriched cultures of spinal and cranial nerve sensory neurons, it has been established that only sensory neurons of neural crest origin are responsive, at least in terms of survival and neurite outgrowth, to mouse submandibular gland nerve growth factor (NGF). Sensory neurons derived from neural placodes (neurons of the ventrolateral portion of the trigeminal ganglion and the entire neuronal population of the vestibular, geniculate, petrosal and nodose ganglia) are largely unresponsive to NGF throughout embryonic development, but do respond to neurotrophic activity present in extracts of brain and various peripheral 'end-organs', such as heart or liver. By incubation of neuron-enriched cultures with radiolabelled [125I]NGF, followed by autoradiographic exposure, it has been demonstrated that placode-derived neurons, in marked contrast to those of neural crest origin, are completely devoid of specific cell surface receptors for NGF. In contrast to differences in their requirement and responsiveness to NGF, both placode- and crest-derived sensory neurons are responsive to the survival and neurite-promoting activity of a recently purified brain-derived neurotrophic factor (BDNF). It is postulated that all primary sensory neurons have a dual growth factor requirement during development; their survival being dependent on a supply of both a peripheral and a central 'target'-derived neurotrophic factor. It appears that BDNF may act as common 'central target-derived' neurotrophic factor for both placode- and crest-derived sensory neurons, but that within peripheral tissues there are specific neurotrophic factors for each of these two classes of primary sensory neurons.

Animals↗
PubMed1984

[Social behavior of 5 to 7-year-old children at risk as newborn infants with special reference to parental child-rearing behavior].

A questionnaire was used to investigate the social behaviour of 168 5-7 year olds, who as neonates had been at risk for developing psychomotor disturbances, and the educational behaviour of their parents. 52 six year olds with an uneventful perinatal period formed the control group. Sociodemographic data did not differ between the two groups. The basic tendency of the children's temperament ( liveliness vs. calmness ) during the first year was similar in both groups. Achievement of developmental milestones (gross motor activity, language, bladder and bowel control) was reached at similar age. The parents' educational behaviour did not differ. The social behaviour of the children at risk, as judged by the inhibited or aggressive behaviour, was also equal to the controls. The psychomotor development of the same population of children had been found to be normal in most cases at age 3-42 (mean 15) months ( Schweiz . med. Wschr . 109, 215 [1979]). According to the present study, this risk population of newborns also showed normal social behaviour.

Age Factors↗
PubMed1983

Presence of nerve growth factor receptors and catecholamine uptake in subpopulations of chick sympathetic neurons: correlation with survival factor requirements in culture.

The presence of nerve growth factor receptors and the imipramine-sensitive uptake of catecholamines in sympathetic neurons of chick embryos were investigated by autoradiography. Neurons were dissociated from paravertebral ganglia of different embryonic ages and receptors and catecholamine uptake were then determined both at the beginning of culture and after 2 days in culture, at which time the number of surviving neurons is determined by the survival factors present. It was found that while essentially all the neurons specifically bound 125I-NGF both after dissociation and at the end of the culture period, only 60% of the neurons take up [3H]norepinephrine after dissociation, and this proportion remained constant through the culture period under conditions where all the neurons survived. All of the neurons maintained by NGF in culture (35% of the total) displayed this uptake, and in contrast, only one-quarter of those maintained by heart cell-conditioned medium alone (60% of the total) took up catecholamines. The uptake was shown to be neither induced by NGF nor suppressed by heart cell-conditioned medium. These results support the hypothesis that chick sympathetic ganglia contain discrete subpopulations of neurons which may be selected in culture by virtue of their different requirements for survival factors.

Animals↗
PubMed1983

Simultaneous expression of neuronal and glial properties by chick ciliary ganglion cells during development.

Autoradiographic methods were used to show that non-neuronal cells from dissociated chick ciliary ganglia grown in cell culture for 1 day exhibit high affinity uptake for norepinephrine (NE) and/or specific receptors for nerve growth factor (NGF). Using immunofluorescence procedures, it was demonstrated that these cells reacted neither with the neuron-specific marker tetanus toxin nor with antibodies to the fibroblast marker fibronectin. The cells were, however, positive for 04 antigen, which is present on Schwann cells and oligodendrocytes and is recognized by a monoclonal antibody (Schachner, M., S. K. KIm, and R. Zehnle (1981) Dev. Biol. 83: 328-338). At all stages studied between embryonic day 6 (E6) and embryonic day 14 (E14), about 80% of the non-neuronal cells were positive for 04 antigen, the other non-neuronal cells being identified as fibroblasts or fibroblast-like cells by staining with antibodies to fibronectin. The proportion of cells with NGF receptors and cells with NE uptake decreased during development between E6 and E14. The percentage of 04-positive cells which have NGF receptors decreased from about 95% at E6 to about 35% at E14. The proportion of 04-positive cells with NE uptake decreased from about 57% at E6 to about 15% at E14. Thus, a considerable proportion of the non-neuronal cell population in embryonic ciliary ganglia displays neuronal properties. We suggest that those cells exhibiting biochemical properties of both differentiated glial cells and neurons are precursor cells which have the potential to develop either into glial cells or neurons.

Animals↗
PubMed1982

Internalization of nerve growth factor by pheochromocytoma PC12 cells: absence of transfer to the nucleus.

The intracellular distribution of 125I-labeled nerve growth factor (NGF) in rat pheochromocytoma PC12 cells was studied by quantitative electron microscopic (EM) autoradiography and by subcellular fractionation. PC12 cells were grown as monolayer cultures in medium supplemented with serum in the presence of 125I-NGF. EM autoradiography showed that 125I-NGF was localized at the plasma membrane and cytoplasmic compartments but did not accumulate in the nuclear chromatin or in the nuclear membrane compartment of cells analyzed after 1 hr and 1, 2, and 8 d of incubation with 125I-NGF. 125I-NGF also was not detected in nuclear subcellular fractions prepared from cells grown in serum-supplemented medium either in suspension for 1 d or in monolayer cultures for 1 to 8 d. In contrast, and in confirmation of the results of Yankner and Shooter (Yankner, B. A., and E. M. Shooter (1979) Pro. Natl. Acad. Sci. U. S. A. 76: 1269-1273), about 60% of the cell-bound 125I-NGF was found in the nuclear pellet after cell fractionation if the cells had been kept previously in suspension for 1 d in phosphate-buffered saline supplemented with 0.2% glucose, 0.1% bovine serum albumin, and 125I-NGF. The ultrastructure of PC12 cells grown under such conditions, however, revealed signs of varying degrees of damage. Autoradiography of the nuclear pellet from these cells showed the grains to be located mainly over damaged nuclei or over cell debris between nuclei. It is concluded that NGF, after binding to specific receptors at the plasma membrane, is transferred to membrane-confined cytoplasmic compartments but does not have to be transferred further to the nuclear membrane or to the nuclear chromatin as a prerequisite for its physiological action.

Animals↗
PubMed1980

Surface proteins of cultured mouse cerebellar cells.

Surface proteins of cultured monolayer cells from embryonic and early postnatal C57BL/6J mouse cerebella were identified by a lactoperoxidase-catalysed 131iodine labelling technique. Major iodinated polypeptides have molecular weights of approximately 200, 145, 120, 100, 85, 65, 50, and 30 x 10(3) (P200, P145,...) as estimated by sodium dodecylsulphate polyacrylamide gel electrophoresis. Membrane glycoproteins, of apparent molecular weights 200, 145, 100, 85, and 50 x 10(3), are detected by biosynthetic labelling with [3H]fucose. The two major iodinated proteins are the glycoproteins P200 and P145. P145 is released from the cells into the medium together with other surface proteins. No changes in the patterns of labelled cerebellar cell surface proteins are detectable between embryonic day 17 and postnatal day 10. A pattern similar to the one seen with cerebellum is obtained with embryonic day 12 and 17 cerebral cortex. Cultured retinal cells from 2-day-old mice, skin fibroblasts, and L-cells display a distinctly different pattern, which does not contain P145 as a major iodinated component. In granule cell-enriched fractions of cerebellar cells the two glycoproteins P200 and P145 are proportionately increased, while three proteins, P100, P85, and P50, are more abundant in the glial cell-enriched fraction. These three polypeptides are also enriched in cells obtained from staggerer mutant mice. An antiserum against 4-day-old cerebellar cells (anti-NS-4) precipitates the 145 and 200 x 10(3) molecular weight proteins, from lysates of both embryonic cerebral and postnatal cerebellar cells. From lysates of mouse retinal cells, anti-NS-4 antiserum precipitates two proteins with molecular weights of 140 and 210 x 10(3).

Animals↗
PubMed1978

Nerve growth factor-mediated induction of tyrosine hydroxylase in rat superior cervical ganglia in vitro.

Exposure of rat sympathetic ganglia to 3 microgram/ml of 2.5 S nerve growth factor (NGF) resulted in a 100% increase in tyrosine hydroxylase activity within 48 h. Pulselabeling of proteins with [3H]leucine, followed by immunoprecipitation with antibodies to tyrosine hydorxylase and isolation of the precipitated enzyme by gel electrophoresis, demonstrated that the increase in tyrosine hydroxylase activity was due to enhanced de novo synthesis. The incorporation of [3H]leucine into tyrosine hydroxylase was increased by 150% compared to a 17% increase in total protein synthesis, which was not statistically significant. The fact that the half-life of pulse-labeled tyrosine hydroxylase was the same for NGF-treated and control organ cultures of superior cervical ganglia excludes the possibility that enhanced tyrosine hydroxylase labeling by NGF is due to decreased degradation. We conclude that, without modulatory factors which play a role in vivo, NGF can enhance the synthesis of tyrosine hydroxylase in sympathetic ganglia in vitro, provided organ culture conditions which permit optimal survival of adrenergic neurons are selected.

Animals↗
PubMed1977

Studies on the transcription complex of Escherichia coli RNA polymerase.

To study the chain elongation phase of enzymatic RNA synthesis ternary transcription complexes with T7 DNA or poly[dA) - (dT)] as template were isolated by gel exclusion chromatography. The DNA in these complexes contains single-stranded regions which are recognized by a single-strand-specific nuclease from Neurospora crassa. The non-codogenic DNA strand in the poly[(dA) - (dT)] ternary complex is preferentially hydrolysed by the nuclease. The polymerase protects predominantly the codogenic strand in this complex from digestion by DNAse I. In the T7 DNA ternary complex a DNA fragment with a chain length of approximately 26 nucleotides and an RNA fragment of about 22 nucleotides are protected by polymerase from digestion by DNAse and RNAse.

Coliphages↗