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C S Goodman

Publications and source records attributed to C S Goodman.

At least 145 records · Page 8Linked to original sources
PubMed1989

The role of segment polarity genes during Drosophila neurogenesis.

Segment polarity genes in Drosophila are required for the proper formation of epidermal pattern within each segment. Here we show that certain segment polarity genes are also critical for the determination of specific neuronal identities in the developing central nervous system (CNS) of the Drosophila embryo. For several mutants, however, the pattern defects do not simply parallel their cuticular phenotypes. In fused, armadillo, and cubitus interruptus Dominant mutants, much of the CNS appears relatively normal. In hedgehog mutants, the CNS is highly disorganized, but this disruption may occur secondary to the initial events of neurogenesis. The specific cellular defects in patched mutants suggests that this gene specifies a subset of neuroblasts and neural progeny underlying the region of epidermal pattern defect. gooseberry mutants display a complex series of alterations in neuronal identity both underlying and outside of the region of epidermal modification. Neuronal identities of a set of cells along the midline appear to be changed in Cell mutants. The phenotype of wingless mutants is the most restricted and may be due to improper communication between sibling neurons. Thus, in addition to their functions in epidermal pattern formation, at least four of the segment polarity genes (gooseberry, patched, Cell, and wingless) appear to have specific roles in the control of cell fates during neurogenesis.

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PubMed1989

Expression of engrailed during segmentation in grasshopper and crayfish.

We have used a monoclonal antibody that recognizes engrailed proteins to compare the process of segmentation in grasshopper, crayfish, and Drosophila. Drosophila embryos rapidly generate metameres during an embryonic stage characterized by the absence of cell division. In contrast, many other arthropod embryos, such as those of more primitive insects and crustaceans, generate metameres gradually and sequentially, as cell proliferation causes caudal elongation. In all three organisms, the pattern of engrailed expression at the segmented germ band stage is similar, and the parasegments are the first metameres to form. Nevertheless, the way in which the engrailed pattern is generated differs and reflects the differences in how these organisms generate their metameres. These differences call into question what role homologues of the Drosophila pair-rule segmentation genes might play in other arthropods that generate metameres sequentially.

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PubMed1989

Embryonic development of axon pathways in the Drosophila CNS. II. Behavior of pioneer growth cones.

We have identified the neurons that pioneer the major CNS axon tracts in the Drosophila embryo and determined their trajectory and fasciculation choices using serial section electron microscopy. Although Drosophila pioneer neurons make choices similar to those of their grasshopper homologs, there are interesting differences that reflect the much smaller nervous system size and the much faster rate of development characteristic of Drosophila. For example, where 2 longitudinal tracts are pioneered independently in grasshopper, only one is formed in Drosophila. This change is due to a change in fasciculation affinity of the pCC growth cone. Additionally, the intersegmental (IS) nerve is pioneered by a different neuron in Drosophila (aCC) than in the grasshopper (U1) because the smaller Drosophila CNS places the IS nerve within filopodial reach of the aCC soma, while in the grasshopper it is not. Drosophila growth cones explore a much more confined neuropil volume than do grasshopper growth cones but can also sample a larger fraction of the CNS as well. For this reason, some cell-cell recognition events critical to pathfinding in the grasshopper embryo may not be as essential in Drosophila. Nevertheless, many specific cellular affinities have been retained through the evolutionary divergence of these 2 species.

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PubMed1989

Embryonic development of axon pathways in the Drosophila CNS. I. A glial scaffold appears before the first growth cones.

Three classes of glial cells are present early in embryogenesis and appear to play a major role in axon pathway formation in the Drosophila CNS. Six longitudinal glial (LG) cells are present over the longitudinal connective on each side of each segment. Six midline glia (MG) cells surround the anterior and posterior commissures of each segment. Finally, the intersegmental nerve root is covered by a glial cell: the segment boundary cell (SBC). All 3 classes of glial cells are present in their final position before axon outgrowth and their pattern prefigures the first axon pathways. The pioneer growth cones that establish the first axon pathways in the longitudinal connective and intersegmental nerve extend along the elongate surface of the LG and SBC glial cells; the pioneer growth cones for the anterior and posterior commissures extend toward and make close contact with the end feet of the MG glial cells. Later, all 3 classes of glial cells enwrap the axon tracts in much the same way as vertebrate oligodendrocytes. The results suggest that these early glial cells provide guidance cues for the first growth cones in the Drosophila CNS. More than simply providing a permissive substrate, the differential extension of specific early growth cones towards either the MG cells or along the LG cells suggests an active role for these glia in growth cone guidance.

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PubMed1988

Growth cone guidance in insects: fasciclin II is a member of the immunoglobulin superfamily.

The cellular cues that guide neuronal growth cones toward their targets are highly conserved in such diverse organisms as insects and vertebrates. Evidence presented here suggests that the molecular mechanisms underlying these events may be equally conserved. This article describes the structure and function of fasciclin II, a glycoprotein expressed on a subset of fasciculating axons in the grasshopper embryo. Antibody perturbation experiments suggest that fasciclin II functions in mediating one form of neuronal recognition: selective fasciculation. Fasciclin II is a member of the immunoglobulin gene superfamily and is homologous in structure and function to the neural cell adhesion molecule N-CAM and to several other vertebrate cell adhesion molecules.

Amino Acid Sequence↗
PubMed1988

Control of neuronal fate by the Drosophila segmentation gene even-skipped.

The central nervous system (CNS) contains a remarkable diversity of cell types. The molecular basis for generating this neuronal diversity is poorly understood. Much is known, however, about the regulatory genes which control segmentation and segment identity during early Drosophila embryogenesis. Interestingly, most of the segmentation and homoeotic genes in Drosophila, as well as many of their vertebrate homologues, are expressed during the development of the nervous system (for example, ref. 3). Are these genes involved in specifying the identity of individual neurons during neurogenesis, just as they specify the identity of cells during segmentation? We previously described the CNS expression of the segmentation gene fushi tarazu (ftz) and showed that ftz CNS expression is involved in the determination of an identified neuron. Here we show that another segmentation gene, even-skipped (eve), is expressed in a different but overlapping subset of neurons. Temperature-sensitive inactivation of the eve protein during neurogenesis alters the fate of two of these neurons. Our results indicate that the nuclear protein products of the eve and ftz segmentation genes are components of the mechanism controlling cell fate during neuronal development.

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PubMed1988

Sequence analysis and neuronal expression of fasciclin I in grasshopper and Drosophila.

The fasciclin I, II, and III glycoproteins are expressed on different subsets of axon bundles (fascicles) in insect embryos and are thus candidates for surface recognition molecules involved in growth cone guidance. Here we present the sequence of grasshopper fasciclin I and the identification and sequence of the Drosophila fasciclin I homolog. In both species, fasciclin I appears to be an extrinsic membrane protein with a signal sequence but no transmembrane region; the protein comprises four homologous domains of approximately 150 amino acids each. Antibodies against Drosophila fasciclin I reveal that it is expressed on the surface of a subset of commissural axon pathways in the embryonic central nervous system and on all sensory axon pathways in the peripheral nervous system. This pattern of expression is similar to that in grasshopper.

Amino Acid Sequence↗
PubMed1988

Drosophila substrate adhesion molecule: sequence of laminin B1 chain reveals domains of homology with mouse.

Laminin, a substrate adhesion molecule in vertebrates, is a large glycoprotein complex in basement membranes that promotes cell adhesion, cell migration, and neurite outgrowth. Here we report on the cloning of the genes encoding the three subunits of Drosophila laminin. Sequence analysis of cDNA clones encoding the Drosophila B1 chain reveals a multidomain structure similar to that of its mouse homolog. The Drosophila sequence has only 25% amino acid identity with the mouse sequence in domains I, II, and IV. However, in one of the putative collagen-binding regions (domain VI) and the two cysteine-rich domains of EGF-like repeats (domains III and V), the amino acid identity between these two evolutionarily distant species jumps to 55%. Moreover, the number, length, and unique amino acid sequences of each of the 13 EGF-like repeats are highly conserved between Drosophila and mouse, suggesting that each may serve a unique function in protein-protein interactions.

Amino Acid Sequence↗
PubMed1988

Molecular genetics of the single-minded locus: a gene involved in the development of the Drosophila nervous system.

The embryonic neuroepithelium of Drosophila gives rise to the central nervous system. We have studied the mutant phenotype and expression of a gene, single-minded (sim), which is involved in generating a specific region of this neuroepithelium. In sim mutant embryos, a subset of neuronal and nonneuronal precursor cells lying along the midline fail to emerge with the rest of the neuroepithelium. We have identified the sim transcription unit and have shown by in situ hybridization to embryos that the sim gene is expressed specifically in the midline neuroepithelium. Both the mutant phenotype and the temporal and spatial expression of transcripts suggest that the sim gene plays a key role in the emergence of this subset of cells along the midline of the developing central nervous system.

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PubMed1988

The Drosophila single-minded gene encodes a nuclear protein with sequence similarity to the per gene product.

Mutations in the single-minded (sim) gene of Drosophila result in the loss of the precursor cells giving rise to the midline cells of the embryonic central nervous system. We have examined the structure of the sim product by sequencing a sim cDNA clone, and have also determined the subcellular localization of the protein and its developmental expression by staining embryos with an antiserum against a sim fusion protein. The results indicate that sim is a nuclear protein specifically expressed along the midline of the neuroepithelium, the same subset of cells that are missing in the mutant. No similarity is observed between sim and any known nuclear protein, but, surprisingly, it is similar to the Drosophila period (per) locus gene product, which controls the periodicity of biological rhythms.

Amino Acid Sequence↗
PubMed1988

Expression and function of the segmentation gene fushi tarazu during Drosophila neurogenesis.

Segmentation genes control cell identities during early pattern formation in Drosophila. One of these genes, fushi tarazu (ftz), is now shown also to control cell fate during neurogenesis. Early in development, ftz is expressed in a striped pattern at the blastoderm stage. Later, it is transiently expressed in a specific subset of neuronal precursor cells, neurons (such as aCC, pCC, RP1, and RP2), and glia in the developing central nervous system (CNS). The function of ftz in the CNS was determined by creating ftz mutant embryos that express ftz in the blastoderm stripes but not in the CNS. In the absence of ftz CNS expression, some neurons appear normal (for example, the aCC, pCC, and RP1), whereas the RP2 neuron extends its growth cone along an abnormal pathway, mimicking its sibling (RP1), suggesting a transformation in neuronal identity.

Animals↗
PubMed1988

Characterization and cloning of fasciclin I and fasciclin II glycoproteins in the grasshopper.

Monoclonal antibodies were previously used to identify two glycoproteins, called fasciclin I and II (70 and 95 kDa, respectively), which are expressed on different subsets of axon fascicles in the grasshopper (Schistocerca americana) embryo. Here the monoclonal antibodies were used to purify these two membrane-associated glycoproteins for further characterization. Fasciclin II appears to be an integral membrane protein, whereas fasciclin I is an extrinsic membrane protein. The amino acid sequences of the amino terminus and fragments of both proteins were determined. Using synthetic oligonucleotide probes and antibody screening, we isolated genomic and cDNA clones. Partial DNA sequences of these clones indicate that they encode fasciclins I and II.

Amino Acid Sequence↗
PubMed1987

Characterization and cloning of fasciclin III: a glycoprotein expressed on a subset of neurons and axon pathways in Drosophila.

To identify candidates for neuronal recognition molecules in Drosophila, we used monoclonal antibodies to search for surface glycoproteins expressed on subsets of axon bundles (or fascicles) during development. Here we report on the characterization and cloning of fasciclin III, which is expressed on a subset of neurons and axon pathways in the Drosophila embryo. Fasciclin III is also expressed at other times and places including transient segmentally repeated patches in the neuroepithelium and segmentally repeated stripes in the body epidermis. Antisera generated against each of four highly related forms of the protein were used for cDNA expression cloning to identify a single gene, which was confirmed to encode fasciclin III by tissue in situ hybridization and genetic deficiency analysis.

Animals↗
PubMed1987

Expression of fasciclin I and II glycoproteins on subsets of axon pathways during neuronal development in the grasshopper.

The "labeled pathways" hypothesis predicts that axon fascicles in the embryonic neuropil are differentially labeled by surface recognition molecules used for growth cone guidance. To identify candidates for such recognition molecules, we generated monoclonal antibodies (MAbs) that recognize surface antigens expressed on subsets of axon fascicles in the grasshopper embryo. The 3B11 and 8C6 MAbs immunoprecipitate 70- and 95-kd membrane glycoproteins called fasciclin I and II, respectively, which are expressed on different subsets of axon fascicles during development. These two glycoproteins are expressed regionally on particular portions of embryonic axons in correlation with their patterns of fasciculation, dynamically during the period of axon outgrowth in a manner consistent with a role in growth cone guidance, and at other times and places during embryogenesis, suggesting multiple developmental roles.

Animals↗
PubMed1987

Neural-specific carbohydrate moiety shared by many surface glycoproteins in Drosophila and grasshopper embryos.

Antiserum against horseradish peroxidase (anti-HRP Ab) labels the surfaces of neurons in both Drosophila and grasshopper (Jan and Jan, 1982). Here we show that the anti-HRP Ab (1) immunoprecipitates at least 17 different membrane glycoproteins from the Drosophila embryo CNS (and a similar array from grasshopper), and (2) recognizes a neural-specific carbohydrate moiety expressed by most if not all of these proteins. Although the anti-HRP Ab stains all axon pathways, 2 of the anti-HRP glycoproteins, fasciclin I and II, are expressed on specific subsets of axon pathways in the grasshopper embryo.

Animals↗
PubMed1986

Guidance of neuronal growth cones in the grasshopper embryo. I. Recognition of a specific axonal pathway by the pCC neuron.

The selective affinities that growth cones display for specific axonal surfaces give rise to stereotyped patterns of selective fasciculation. Previous studies on cell recognition by neuronal growth cones in the grasshopper embryo led to the proposal and initial experimental testing of the labeled-pathways hypothesis. Here we report on a further experimental analysis of this hypothesis, using the first 3 longitudinal axon fascicles, which initially contain only the axons of 7 identified neurons. We describe and experimentally test the selective affinity of the pCC growth cone for the MP1 and dMP2 axons in the MP1/dMP2 fascicle. The pCC growth cone appears to demonstrate an absolute, rather than hierarchical, preference for the MP1/dMP2 fascicle, as compared with other longitudinal axon fascicles, which supports the notion that the surfaces of the MP1 and dMP2 axons have some special distinguishing label that guides the pCC growth cone onto and along them.

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