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C S Goodman

Publications and source records attributed to C S Goodman.

At least 181 records · Page 10Linked to original sources
PubMed1984

Pathfinding by neuronal growth cones in grasshopper embryos. III. Selective affinity of the G growth cone for the P cells within the A/P fascicle.

The growth cone of the G neuron selectively fasciculates upon specific axon bundles in a stereotypic sequence as it navigates through the developing central nervous system of the grasshopper embryo. It turns and extends anteriorly in the contralateral neuropil of the second thoracic ganglion at a specific choice point where it fasciculates with the A/P axon bundle which contains the axons of the A1, A2, P1, and P2 neurons. We previously hypothesized (Raper, J. A., M. J. Bastiani, and C. S. Goodman (1983) J. Neurosci. 3: 20-41) that this fascicle, or subsets of axons within it, were specifically labeled and that the G neuron was determined to follow this labeled pathway. Here we report on an ultrastructural analysis of the interactions between the G growth cone and its filopodia with the cells of the A/P fascicle at the choice point. As G reaches its choice point, its filopodia are in more frequent contact with the A/P fascicle in comparison to the other longitudinal axon fascicles. Within the A/P fascicle, the tip of G's growth cone is found to be closely associated with the P and not the A axons. Furthermore, before the G growth cone climbs onto the A/P fascicle, its filopodia show a selective affinity for the P axons as compared to the A axons. Another specific interaction involves selective filopodial insertions; only filopodia from the P cells were found to insert into the G growth cone and induce coated pits and vesicles. These findings suggest that G is able to distinguish the A/P fascicle from other axon bundles and, moreover, is able to distinguish the P axons from the A axons. The companion paper (Raper, J. A., M. J. Bastiani, and C. S. Goodman (1984) J. Neurosci. 4: 2329-2345) presents experimental results based on specific axon ablations that further support this hypothesis.

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PubMed1984

Pathfinding by neuronal growth cones in grasshopper embryos. IV. The effects of ablating the A and P axons upon the behavior of the G growth cone.

In the companion paper (Bastiani, M. J., J. A. Raper, and C. S. Goodman (1984) J. Neurosci. 4: 2311-2328), we show that as the G growth cone reaches its choice point and turns anteriorly on the A/P fascicle, its filopodia demonstrate selective affinity for the A/P fascicle as compared to the other approximately 25 longitudinal axon fascicles, and within the A/P fascicle itself, G's filopodia selectively contact the P axons as compared to the A axons. These results support the hypothesis that the A/P fascicle, and, moreover, subsets of axons within it (Ps versus As), are specifically labeled and that the G growth cone is determined to follow a particular labeled pathway. We tested the "labeled pathways" hypothesis by specifically ablating these axons and examining the subsequent behavior of the G growth cone in embryos grown in culture. Ablation of the A and P axons prevents G from growing more than a short distance anteriorly, although the G growth cone is within grasp of many other longitudinal axon fascicles. Ablation of only the P axons has a similar effect; the G growth cone behaves normally if only the A axons are ablated. Transmission electron micrograph semiserial section reconstructions of experimental embryos further indicate that G's growth cone behaves abnormally when the A and P axons, or only the P axons, are ablated. The G growth cone branches extensively in the lateral and ventral neuropil without it or its filopodia showing a high affinity for any other axon fascicle. These results indicate that the G growth cone is able to distinguish the A/P fascicle from the other longitudinal axon fascicles in the developing neuropil. Moreover, the results suggest that within the A/P fascicle the G growth cone is able to distinguish the P axons from the A axons.

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PubMed1983

Muscle pioneers: large mesodermal cells that erect a scaffold for developing muscles and motoneurones in grasshopper embryos.

During embryonic development, muscles differentiate in the appropriate places and motoneurone growth cones find the appropriate muscles; both events occur concurrently and with remarkable specificity. What are the cellular interactions that orchestrate this coordinated development of nerve and muscle? In the development of vertebrate skeletal muscles, motoneurone growth cones arrive in the periphery along stereotyped routes and enter the appropriately located masses of mesodermal cells usually before differentiated muscle fibres appear and before the masses cleave into separate muscles. We find that a similar sequence of events occurs in the grasshopper embryo. We are interested in how mesodermal cells become organized into the appropriate muscles and what guides motoneurone growth cones to their appropriate targets. Fortunately, in the grasshopper embryo the mesodermal cells in the periphery and motoneurones in the central nervous system (CNS) are large, accessible and in many cases individually identifiable from early in their development. We report here the discovery of a class of large mesodermal cells, which we call muscle pioneers, that arise early in development when the embryonic environment is relatively simple and distances short. By their growth and association with particular sites along the ectoderm, the muscle pioneers appear to erect a scaffold for later developing muscles and motoneurone growth cones.

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PubMed1983

Selective groups of neuronal and mesodermal cells recognized early in grasshopper embryogenesis by a monoclonal antibody.

Our aim in generating monoclonal antibodies against the grasshopper nervous system is to identify molecules expressed early in neuronal development. A crude homogenate of the adult nervous system was used as the immunogen, and the hybridoma supernatants were screened on young grasshopper embryos. Here we report on the I-5 monoclonal antibody, which recognizes an antigen appearing in an interesting pattern of ectodermal and mesodermal cells early in the embryonic development of the grasshopper. Amongst the cells stained are the pioneer neurons in the central nervous system and the periphery, and the muscle pioneers.

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PubMed1983

Neuronal cell death in grasshopper embryos: variable patterns in different species, clutches, and clones.

Previous studies showed that cell death plays an important role in adjusting the segment-specific number of ganglionic neurones during grasshopper embryogenesis (Bate, Goodman & Spitzer, 1979; Goodman & Bate, 1981). In every segment, the single midline precursor 3 (MP3) divides once to produce two progeny. In some segments, one or both of these two progeny die; there is a general pattern of cell death of the MP3 progeny across the thoracic and abdominal segments. In the present study we examined the pattern of cell survival versus death of the MP3 progeny in 472 embryos from four different species, from the genetically related offspring within different clutches of the same species and from the genetically identical offspring within isogenic clones of the same species. We find variability in the pattern of cell survival versus death amongst embryos of the same species, clutch and clone, suggesting a significant epigenetic influence on this pattern. However, our results also show significant differences in the pattern of cell death between different genera and species, and between different clones and clutches within a single species, suggesting a genetic influence on this pattern as well.

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PubMed1983

Pathfinding by neuronal growth cones in grasshopper embryos. I. Divergent choices made by the growth cones of sibling neurons.

We are interested in how the growth cones of identified neurons navigate in the central nervous system of the grasshopper embryo. The behavior of identified growth cones was observed as a function of developmental time by (i) periodically removing embryos from synchronized clutches of eggs and (ii) filling identified neurons in the central nervous system with the fluorescent dye Lucifer Yellow. We examined the first six progeny of the identified neuronal precursor cell, neuroblast 7-4: the Q1, Q2, G, C, Q5, and Q6 neurons. Their growth cones extend sequentially upon the same route across the midline of the posterior commissure of the developing ganglionic neuropil. However, after reaching the contralateral side of the neuropil, their growth cones diverge from each other at reproducible, cell-specific choice points. By focusing our attention on one such choice point, at which the growth cone of the G neuron turns anteriorly while the growth cone of its sibling C neuron turns posteriorly, we hope to elucidate the environmental cues which guide individual growth cones.

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PubMed1983

Pathfinding by neuronal growth cones in grasshopper embryos. II. Selective fasciculation onto specific axonal pathways.

In the previous paper (Raper, J.A., M. Bastiani, and C.S. Goodman (1983) J. Neurosci. 3:20-30) we showed that the growth cones of two sibling neurons, the G and C cells, follow the same route in the developing grasshopper neuropil until they reach a stereotypic choice point. Here their growth cones diverge from each other as G turns and extends anteriorly and C turns and extends posteriorly. In this paper we show that the G and C growth cones fasciculate and extend in opposite directions upon a specific bundle of four axons. This occurs even though many other axons are within filopodial reach of the G and C growth cones. We identified the four neurons (the A1, A2, P1, and P2 cells) whose axons form the bundle that G and C extend upon by filling individual axons with Lucifer Yellow and viewing the filled cells in living embryos and by filling individual neurons with HRP and reconstructing the axon bundle from electron micrographs. The G neuron extends anteriorly in the bundle containing these four axons; the C neuron extends posteriorly in the same bundle only after several other axons have joined in. These results suggest that the growth cones of the G and C neurons are determined to recognize and extend upon labeled axons, leading us to propose the "labeled pathways" hypothesis.

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PubMed1981

The mature electrical properties of identified neurones in grasshopper embryos.

1. We have examined the mature electrical properties of five identified neurones in embryos of the grasshopper Schistocerca nitens. The five cells arise from two different precursor cells: the median neuroblast, whose first three progency are called DUM 3,4,5; DUM 4,5; and DUM 5; and mid-line precursor 3, which divides once to produce the H cell and the H cell sibling.2. Electrical coupling was investigated by dual intracellular penetrations. Action potentials were elicited by intracellular stimulation of cell bodies and by extracellular stimulation of axons. The ionic basis of action potentials was investigated by changing the ionic environment and by applying various blocking agents.3. Most of the mature electrical properties of all five cells appear by day 13 of embryonic development. They change little through hatching on day 20.4. The recorded resting potential for all five cells varies from -55 to -60 mV and the recorded input resistance varies from 200 to 450 MOmega. All five cells show delayed rectification, much of which is blocked by tetraethylammonium (TEA). Their resistance increases as they are hyperpolarized.5. The five cells do not appear to be electrically coupled between days 13 and 20.6. All five neurones generate mature action potentials and in several cases show cell-specific electrical properties by day 13. The ionic dependence and depolarizing phase of the action potential change little between days 13 and 20; some changes occur in the after-hyperpolarization.7. One cell-specific difference is observed in normal saline. Four of the cells have axons, median neurites, and somata which generate action potentials in normal saline; but one of the cells (the H cell sibling) has an inexcitable soma and generates action potentials only in its axon.8. Another cell-specific difference in the soma action potentials of DUM 3,4,5,; DUM 4,5; DUM 5; and the H cell is observed when outward current is blocked by TEA. In three of the cells, TEA causes the short-duration action potential (2-4 msec) to be converted into a long-duration action potential (100-1000 msec) in which there is an initial spike (Na(+)-dependent) followed by a long plateau (Ca(2+)-dependent). In the other cell, DUM 5, at resting potential the addition of TEA only causes a shoulder (Ca(2+)-dependent) on the falling phase of the action potential. DUM 5 and DUM 4,5 thus have different electrical properties, even though they differ only by a single cell division from the precursor cell.9. In all four neurones which normally generate soma action potentials (DUM 3,4,5; DUM 4,5; DUM 5; and the H cell), the inward current is carried by both Na(+) and Ca(2+). On day 13, either inward current alone can generate the overshooting action potential; in contrast, by day 18, neither inward current alone can generate an overshooting response. The inward current of the axon action potential in all five cells is carried predominantly by Na(+).10. Thus, the progeny of two different embryonic precursor cells (median neuroblast and mid-line precursor 3) show a broad spectrum of electrical properties. The mature phenotype of electrical excitability is not a property shared in common by all the progeny of a single embryonic precursor cell in the grasshopper. Conversely, progeny from different precursor cells can share the same mature phenotype of electrical excitability.

Action Potentials↗
PubMed1981

The development of electrical properties of identified neurones in grasshopper embryos.

1. We have examined the development of the electrical properties of five identified neurones in grasshopper embryos between days 10 and 13 of embryogenesis (hatching occurs on day 20). DUM 3,4,5; DUM 4,5; DUM 5; the H cell; and the H cell sibling are the progeny of two different precursor cells. Electrical coupling and electrical excitability were assayed by intracellular recordings. 2. Midway through embryogenesis, on day 10, the five cells are highly electrically coupled to each other and are electrically inexcitable. The temporal sequence of the development of electrical excitability and electrical coupling is described for DUM 3,4,5; 4,5; and 5. The H cell and H cell sib undergo the same sequence one day later. 3. The first non-linear membrane property to appear is delayed rectification which appears on day 11 and can be blocked by tetraethylammonium (TEA). In some cells at about day 11, the addition of TEA to normal saline unmasks a Na+-dependent action potential in the axon. 4. The first action potential in normal saline is a Na+-dependent response that appears in the axon at day 11-11.5. 5. The next stage of excitability in normal saline is the appearance about day 11.5 of a Na+-dependent action potential in the median neurite between the soma and the two axons. In some cells at about day 11.5, the addition of TEA unmasks an excitable response in the soma. 6. Overshooting action potentials appear in the soma about day 12; the inward current is carried by both Na+ and Ca2+; TEA causes a prolonged shoulder on the falling phase of the action potential. A short time later, TEA causes a long-duration CA2+ plateau. 7. A progressive decrease in the degree of electrical coupling among the cells occurs between days 10 and 12.5. Complete uncoupling is never observed before day 11, but has always occurred by day 12.5. 8. Two methods were used to demonstrate that electrical coupling does not mask the presence of excitable inward current channels and thus make the cells appear inexcitable. First, we exposed the cells to veratridine. The cells which normally generate excitable Na+ response are depolarized by it; the younger inexcitable cells are not. Secondly, we electrically isolated the cells by killing the somata of their neighbours. The input resistance increased, yet the extent of excitability remained unchanged. 9. There is variability in the precise temporal relationship of excitability and uncoupling. Pairs of cells from different embryos of the same ate can generate the same type of action potentials and yet be coupled in one embryo and uncoupled in another. Electrical excitability and uncoupling appear to be causally unrelated and independent events, occurring at about the same developmental stage.

Action Potentials↗
PubMed1981

Presynaptic inhibition of transmission from identified interneurons in locust central nervous system.

1. Intracellular recordings near the output terminals of an identified interneuron (the descending contralateral movement detector, DCMD) in the locust revealed the occurrence of depolarizing synaptic potentials. These presynaptic depolarizing potentials were evoked by spikes in both DCMDs, by auditory stimuli, and by electrical stimulation of the pro- to mesothoracic connectives. The occurrence of the depolarizing potentials decreased the amplitude of the action potentials close to the output terminals. 2. The stimuli that produced depolarizing potentials in the presynaptic terminals reduced the amplitude of the monosynaptic excitatory postsynaptic potentials evoked by the DCMDs in identified follower interneurons. We conclude that at least part of this reduction in transmission from the DCMDs results from presynaptic inhibition and that the presynaptic inhibition is related to a reduction in the amplitude of the presynaptic action potentials. 3. We propose that the function of the presynaptic inhibition of the DCMDs is to ensure that the interneurons triggering a jump are never activated by the DCMDs in the absence of proprioceptive signals from the legs indicating the animal's readiness to jump.

Action Potentials↗
PubMed1981

Embryonic development of identified neurons: segment-specific differences in the H cell homologues.

Although all of the segmental ganglia of the grasshopper come from identical sets of embryonic precursor cells, there are striking differences in the number and properties of the neurons in the mature ganglia. In every segment, midline precursor 3 (MP3) divides once and gives rise to two progeny. We describe the fate of the two MP3 progeny in different segments. The morphology, physiology, and survival of the MP3 progeny depend upon their segmental position in the embryo. In the meso- and metathoracic segments (T2 and T3), one of the two progeny of MP3 transforms into the H cell. In many of the abdominal segments, beginning with the fourth (A4), both MP3 progeny die. A gradient of transformation and cell death is seen in the intervening first three abdominal segments (A1 to A3). From A1 to A3, the MP3 progeny acquire fewer of the morphological phenotypes of the H cell. This is paralleled by the partial acquisition of the physiological phenotypes of the H cell. Thus, cells that are the progeny of the same precursor cell in different segments can either live or die and, if they survive, can develop different morphological and physiological properties.

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