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Genetic transformation of structural and functional circuitry rewires the Drosophila brain.

Sen S, Cao D, Choudhary R, Biagini S, Wang JW, Reichert H, VijayRaghavan K - Elife (2014)

Bottom Line: However, the extent to which individual factors can contribute to this is poorly understood.Loss of orthodenticle from this neuroblast affects molecular properties, neuroanatomical features, and functional inputs of progeny neurons, such that an entire central complex lineage transforms into a functional olfactory projection neuron lineage.This ability to change functional macrocircuitry of the brain through changes in gene expression in a single neuroblast reveals a surprising capacity for novel circuit formation in the brain and provides a paradigm for large-scale evolutionary modification of circuitry.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Biology and Genetics, National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, India.

ABSTRACT
Acquisition of distinct neuronal identities during development is critical for the assembly of diverse functional neural circuits in the brain. In both vertebrates and invertebrates, intrinsic determinants are thought to act in neural progenitors to specify their identity and the identity of their neuronal progeny. However, the extent to which individual factors can contribute to this is poorly understood. We investigate the role of orthodenticle in the specification of an identified neuroblast (neuronal progenitor) lineage in the Drosophila brain. Loss of orthodenticle from this neuroblast affects molecular properties, neuroanatomical features, and functional inputs of progeny neurons, such that an entire central complex lineage transforms into a functional olfactory projection neuron lineage. This ability to change functional macrocircuitry of the brain through changes in gene expression in a single neuroblast reveals a surprising capacity for novel circuit formation in the brain and provides a paradigm for large-scale evolutionary modification of circuitry.

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Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.(A and B) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the larval brain. (A) shows that the cell bodies are closely apposed to each other and lie above the larval antennal lobe (AL, yellow), (B) shows their tracts diverge—the ALad1 tract (magenta) projects dorsally and the LALv1 tract (green) projects posteriorly behind the AL and splits. (C and D) show WT MARCM clones of the larval ALad1 and LALv1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the white arrows trace their tracts. Insets in C and D show that while LALv1 cells (cyan arrow in D) express Otd, ALad1 cells (cyan arrow in C) do not. (E–L) is a third larval instar brain (CS) immunolabelled with neurotactin (green, to identify lineages), Otd (red) and TOPRO-3 (to label nuclei). The LALv1 lineage is documented in E–H, and the ALad1 lineage is documented in I–L. The neuroblasts are marked with yellow dotted lines and the lineages are marked with white dotted lines. The LALv1 neuroblast expresses Otd (yellow arrow in F) and the ALad1 neuroblast does not (yellow arrow in J). (M and N) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the adult brain. Note that the adult antennal lobe (AL, yellow in M and N) is situated between the ALad1 lineage (antero-dorsal to AL) and the LALv1 lineage (ventral to AL) and the cell bodies of these lineages are not closely apposed anymore. The arrows in M and N indicate the ALad1 tract (magenta), which projects dorsally towards the protocerebrum and the LALv1 tract (green), which projects posterior to the AL. (O and P) show WT clones of the adult LALv1 and ALad1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the AL is outlined by yellow dotted lines. White arrows trace the tracts of these lineages. The LALv1 lineage innervates the lateral accessory lobe (LAL) and the central complex (CC). The ALad1 lineage innervates the calyx of the mushroom body (MB) and lateral horn (LH). The midline is represented by a yellow line in all images. Scale bars in C (applicable to D) and in L (applicable to E–L) are 20 µm. Scale bar in P (applicable to O) is 50 µm. Genotypes in C and D: FRT19A/FRT19A,Tub-Gal80,hsFLP; Tub-Gal4,UAS-mCD8::GFP/+. Genotype in O: FRT19A/FRT19A,Tub-Gal80,hsFLP; Per-Gal4,UAS-mCD8::GFP/+. Genotype in P: FRT19A/FRT19A,Tub-Gal80,hsFLP; GH146-Gal4,UAS-mCD8::GFP/+.DOI:http://dx.doi.org/10.7554/eLife.04407.003
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fig1: Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.(A and B) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the larval brain. (A) shows that the cell bodies are closely apposed to each other and lie above the larval antennal lobe (AL, yellow), (B) shows their tracts diverge—the ALad1 tract (magenta) projects dorsally and the LALv1 tract (green) projects posteriorly behind the AL and splits. (C and D) show WT MARCM clones of the larval ALad1 and LALv1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the white arrows trace their tracts. Insets in C and D show that while LALv1 cells (cyan arrow in D) express Otd, ALad1 cells (cyan arrow in C) do not. (E–L) is a third larval instar brain (CS) immunolabelled with neurotactin (green, to identify lineages), Otd (red) and TOPRO-3 (to label nuclei). The LALv1 lineage is documented in E–H, and the ALad1 lineage is documented in I–L. The neuroblasts are marked with yellow dotted lines and the lineages are marked with white dotted lines. The LALv1 neuroblast expresses Otd (yellow arrow in F) and the ALad1 neuroblast does not (yellow arrow in J). (M and N) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the adult brain. Note that the adult antennal lobe (AL, yellow in M and N) is situated between the ALad1 lineage (antero-dorsal to AL) and the LALv1 lineage (ventral to AL) and the cell bodies of these lineages are not closely apposed anymore. The arrows in M and N indicate the ALad1 tract (magenta), which projects dorsally towards the protocerebrum and the LALv1 tract (green), which projects posterior to the AL. (O and P) show WT clones of the adult LALv1 and ALad1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the AL is outlined by yellow dotted lines. White arrows trace the tracts of these lineages. The LALv1 lineage innervates the lateral accessory lobe (LAL) and the central complex (CC). The ALad1 lineage innervates the calyx of the mushroom body (MB) and lateral horn (LH). The midline is represented by a yellow line in all images. Scale bars in C (applicable to D) and in L (applicable to E–L) are 20 µm. Scale bar in P (applicable to O) is 50 µm. Genotypes in C and D: FRT19A/FRT19A,Tub-Gal80,hsFLP; Tub-Gal4,UAS-mCD8::GFP/+. Genotype in O: FRT19A/FRT19A,Tub-Gal80,hsFLP; Per-Gal4,UAS-mCD8::GFP/+. Genotype in P: FRT19A/FRT19A,Tub-Gal80,hsFLP; GH146-Gal4,UAS-mCD8::GFP/+.DOI:http://dx.doi.org/10.7554/eLife.04407.003

Mentions: We focused our analysis on two identified neuroblast lineages referred to as LALv1 and ALad1 (Pereanu and Hartenstein, 2006; Lovick et al., 2013) (see ‘Materials and methods’ for lineage nomenclature). During postembryonic development in the larval brain, the adult-specific (postembryonically generated) neural progeny of these lineages have their cell bodies clustered close to each other, dorsal to the larval antennal lobe (Figure 1A,B). Although their cell body clusters are closely apposed, the two lineages can be easily identified based on their distinct and unique axon tracts that project to different brain regions (Pereanu et al., 2010; Das et al., 2013; Lovick et al., 2013).10.7554/eLife.04407.003Figure 1.Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.


Genetic transformation of structural and functional circuitry rewires the Drosophila brain.

Sen S, Cao D, Choudhary R, Biagini S, Wang JW, Reichert H, VijayRaghavan K - Elife (2014)

Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.(A and B) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the larval brain. (A) shows that the cell bodies are closely apposed to each other and lie above the larval antennal lobe (AL, yellow), (B) shows their tracts diverge—the ALad1 tract (magenta) projects dorsally and the LALv1 tract (green) projects posteriorly behind the AL and splits. (C and D) show WT MARCM clones of the larval ALad1 and LALv1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the white arrows trace their tracts. Insets in C and D show that while LALv1 cells (cyan arrow in D) express Otd, ALad1 cells (cyan arrow in C) do not. (E–L) is a third larval instar brain (CS) immunolabelled with neurotactin (green, to identify lineages), Otd (red) and TOPRO-3 (to label nuclei). The LALv1 lineage is documented in E–H, and the ALad1 lineage is documented in I–L. The neuroblasts are marked with yellow dotted lines and the lineages are marked with white dotted lines. The LALv1 neuroblast expresses Otd (yellow arrow in F) and the ALad1 neuroblast does not (yellow arrow in J). (M and N) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the adult brain. Note that the adult antennal lobe (AL, yellow in M and N) is situated between the ALad1 lineage (antero-dorsal to AL) and the LALv1 lineage (ventral to AL) and the cell bodies of these lineages are not closely apposed anymore. The arrows in M and N indicate the ALad1 tract (magenta), which projects dorsally towards the protocerebrum and the LALv1 tract (green), which projects posterior to the AL. (O and P) show WT clones of the adult LALv1 and ALad1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the AL is outlined by yellow dotted lines. White arrows trace the tracts of these lineages. The LALv1 lineage innervates the lateral accessory lobe (LAL) and the central complex (CC). The ALad1 lineage innervates the calyx of the mushroom body (MB) and lateral horn (LH). The midline is represented by a yellow line in all images. Scale bars in C (applicable to D) and in L (applicable to E–L) are 20 µm. Scale bar in P (applicable to O) is 50 µm. Genotypes in C and D: FRT19A/FRT19A,Tub-Gal80,hsFLP; Tub-Gal4,UAS-mCD8::GFP/+. Genotype in O: FRT19A/FRT19A,Tub-Gal80,hsFLP; Per-Gal4,UAS-mCD8::GFP/+. Genotype in P: FRT19A/FRT19A,Tub-Gal80,hsFLP; GH146-Gal4,UAS-mCD8::GFP/+.DOI:http://dx.doi.org/10.7554/eLife.04407.003
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4307181&req=5

fig1: Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.(A and B) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the larval brain. (A) shows that the cell bodies are closely apposed to each other and lie above the larval antennal lobe (AL, yellow), (B) shows their tracts diverge—the ALad1 tract (magenta) projects dorsally and the LALv1 tract (green) projects posteriorly behind the AL and splits. (C and D) show WT MARCM clones of the larval ALad1 and LALv1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the white arrows trace their tracts. Insets in C and D show that while LALv1 cells (cyan arrow in D) express Otd, ALad1 cells (cyan arrow in C) do not. (E–L) is a third larval instar brain (CS) immunolabelled with neurotactin (green, to identify lineages), Otd (red) and TOPRO-3 (to label nuclei). The LALv1 lineage is documented in E–H, and the ALad1 lineage is documented in I–L. The neuroblasts are marked with yellow dotted lines and the lineages are marked with white dotted lines. The LALv1 neuroblast expresses Otd (yellow arrow in F) and the ALad1 neuroblast does not (yellow arrow in J). (M and N) show anterior and lateral views of 3D reconstructions of the LALv1 (green) and the ALad1 (magenta) lineages in the adult brain. Note that the adult antennal lobe (AL, yellow in M and N) is situated between the ALad1 lineage (antero-dorsal to AL) and the LALv1 lineage (ventral to AL) and the cell bodies of these lineages are not closely apposed anymore. The arrows in M and N indicate the ALad1 tract (magenta), which projects dorsally towards the protocerebrum and the LALv1 tract (green), which projects posterior to the AL. (O and P) show WT clones of the adult LALv1 and ALad1 lineages, respectively. Their cell bodies are outlined by white dotted lines and the AL is outlined by yellow dotted lines. White arrows trace the tracts of these lineages. The LALv1 lineage innervates the lateral accessory lobe (LAL) and the central complex (CC). The ALad1 lineage innervates the calyx of the mushroom body (MB) and lateral horn (LH). The midline is represented by a yellow line in all images. Scale bars in C (applicable to D) and in L (applicable to E–L) are 20 µm. Scale bar in P (applicable to O) is 50 µm. Genotypes in C and D: FRT19A/FRT19A,Tub-Gal80,hsFLP; Tub-Gal4,UAS-mCD8::GFP/+. Genotype in O: FRT19A/FRT19A,Tub-Gal80,hsFLP; Per-Gal4,UAS-mCD8::GFP/+. Genotype in P: FRT19A/FRT19A,Tub-Gal80,hsFLP; GH146-Gal4,UAS-mCD8::GFP/+.DOI:http://dx.doi.org/10.7554/eLife.04407.003
Mentions: We focused our analysis on two identified neuroblast lineages referred to as LALv1 and ALad1 (Pereanu and Hartenstein, 2006; Lovick et al., 2013) (see ‘Materials and methods’ for lineage nomenclature). During postembryonic development in the larval brain, the adult-specific (postembryonically generated) neural progeny of these lineages have their cell bodies clustered close to each other, dorsal to the larval antennal lobe (Figure 1A,B). Although their cell body clusters are closely apposed, the two lineages can be easily identified based on their distinct and unique axon tracts that project to different brain regions (Pereanu et al., 2010; Das et al., 2013; Lovick et al., 2013).10.7554/eLife.04407.003Figure 1.Development, morphogenesis, and differential Otd expression in two identified central brain neuroblast lineages, LALv1 and ALad1.

Bottom Line: However, the extent to which individual factors can contribute to this is poorly understood.Loss of orthodenticle from this neuroblast affects molecular properties, neuroanatomical features, and functional inputs of progeny neurons, such that an entire central complex lineage transforms into a functional olfactory projection neuron lineage.This ability to change functional macrocircuitry of the brain through changes in gene expression in a single neuroblast reveals a surprising capacity for novel circuit formation in the brain and provides a paradigm for large-scale evolutionary modification of circuitry.

View Article: PubMed Central - PubMed

Affiliation: Department of Developmental Biology and Genetics, National Centre for Biological Sciences, Tata Institute for Fundamental Research, Bangalore, India.

ABSTRACT
Acquisition of distinct neuronal identities during development is critical for the assembly of diverse functional neural circuits in the brain. In both vertebrates and invertebrates, intrinsic determinants are thought to act in neural progenitors to specify their identity and the identity of their neuronal progeny. However, the extent to which individual factors can contribute to this is poorly understood. We investigate the role of orthodenticle in the specification of an identified neuroblast (neuronal progenitor) lineage in the Drosophila brain. Loss of orthodenticle from this neuroblast affects molecular properties, neuroanatomical features, and functional inputs of progeny neurons, such that an entire central complex lineage transforms into a functional olfactory projection neuron lineage. This ability to change functional macrocircuitry of the brain through changes in gene expression in a single neuroblast reveals a surprising capacity for novel circuit formation in the brain and provides a paradigm for large-scale evolutionary modification of circuitry.

Show MeSH