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Hirata K, Shiga S. Bolwig Organ and Its Role in the Photoperiodic Response of Sarcophaga similis Larvae. INSECTS 2023; 14:115. [PMID: 36835683 PMCID: PMC9959995 DOI: 10.3390/insects14020115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
Flesh-fly Sarcophaga similis larvae exhibit a photoperiodic response, in which short days induce pupal diapause for seasonal adaptation. Although the spectral sensitivity of photoperiodic photoreception is known, the photoreceptor organ remains unclear. We morphologically identified the Bolwig organ, a larval-photoreceptor identified in several other fly species, and examined the effects of its removal on the photoperiodic response in S. similis. Backfill-staining and embryonic-lethal-abnormal-vision (ELAV) immunohistochemical-staining identified ~34 and 38 cells, respectively, in a spherical body at the ocular depression of the cephalopharyngeal skeleton, suggesting that the spherical body is the Bolwig organ in S. similis. Forward-fill and immunohistochemistry revealed that Bolwig-organ neurons terminate in the vicinity of the dendritic fibres of pigment-dispersing factor-immunoreactive and potential circadian-clock neurons in the brain. After surgical removal of the Bolwig-organ regions, diapause incidence was not significantly different between short and long days, and was similar to that in the insects with an intact organ, under constant darkness. However, diapause incidence was not significantly different between the control and Bolwig-organ-removed insects for each photoperiod. These results suggest that the Bolwig organ contributes partially to photoperiodic photoreception, and that other photoreceptors may also be involved.
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Affiliation(s)
- Kazuné Hirata
- Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
- Center for Ecological Research, Kyoto University, Otsu 520-2133, Shiga, Japan
| | - Sakiko Shiga
- Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
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Hartenstein V, Yuan M, Younossi-Hartenstein A, Karandikar A, Bernardo-Garcia FJ, Sprecher S, Knust E. Serial electron microscopic reconstruction of the drosophila larval eye: Photoreceptors with a rudimentary rhabdomere of microvillar-like processes. Dev Biol 2019; 453:56-67. [PMID: 31158364 DOI: 10.1016/j.ydbio.2019.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 11/26/2022]
Abstract
Photoreceptor cells (PRCs) across the animal kingdom are characterized by a stacking of apical membranes to accommodate the high abundance of photopigment. In arthropods and many other invertebrate phyla PRC membrane stacks adopt the shape of densely packed microvilli that form a structure called rhabdomere. PRCs and surrounding accessory cells, including pigment cells and lens-forming cells, are grouped in stereotyped units, the ommatidia. In larvae of holometabolan insects, eyes (called stemmata) are reduced in terms of number and composition of ommatidia. The stemma of Drosophila (Bolwig organ) is reduced to a bilateral cluster of subepidermal PRCs, lacking all other cell types. In the present paper we have analyzed the development and fine structure of the Drosophila larval PRCs. Shortly after their appearance in the embryonic head ectoderm, PRC precursors delaminate and lose expression of apical markers of epithelial cells, including Crumbs and several centrosome-associated proteins. In the early first instar larva, PRCs show an expanded, irregularly shaped apical surface that is folded into multiple horizontal microvillar-like processes (MLPs). Apical PRC membranes and MLPs are covered with a layer of extracellular matrix. MLPs are predominantly aligned along an axis that extends ventro-anteriorly to dorso-posteriorly, but vary in length, diameter, and spacing. Individual MLPs present a "beaded" shape, with thick segments (0.2-0.3 μm diameter) alternating with thin segments (>0.1 μm). We show that loss of the glycoprotein Chaoptin, which is absolutely essential for rhabdomere formation in the adult PRCs, does not lead to severe abnormalities in larval PRCs.
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Affiliation(s)
- Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA, 90095, USA.
| | - Michaela Yuan
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany
| | - Amelia Younossi-Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Aanavi Karandikar
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | | | - Simon Sprecher
- Department of Biology, University of Fribourg, 10, Ch. du Musée, 1700, Fribourg, Switzerland
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany
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Baker NE, Brown NL. All in the family: proneural bHLH genes and neuronal diversity. Development 2018; 145:145/9/dev159426. [PMID: 29720483 DOI: 10.1242/dev.159426] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Proneural basic Helix-Loop-Helix (bHLH) proteins are required for neuronal determination and the differentiation of most neural precursor cells. These transcription factors are expressed in vastly divergent organisms, ranging from sponges to primates. Here, we review proneural bHLH gene evolution and function in the Drosophila and vertebrate nervous systems, arguing that the Drosophila gene atonal provides a useful platform for understanding proneural gene structure and regulation. We also discuss how functional equivalency experiments using distinct proneural genes can reveal how proneural gene duplication and divergence are interwoven with neuronal complexity.
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Affiliation(s)
- Nicholas E Baker
- Department of Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
| | - Nadean L Brown
- Department of Cell Biology and Human Anatomy, University of California, One Shields Avenue, Davis, CA 95616 USA
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Mishra AK, Bernardo-Garcia FJ, Fritsch C, Humberg TH, Egger B, Sprecher SG. Patterning mechanisms diversify neuroepithelial domains in the Drosophila optic placode. PLoS Genet 2018; 14:e1007353. [PMID: 29677185 PMCID: PMC5937791 DOI: 10.1371/journal.pgen.1007353] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 05/07/2018] [Accepted: 04/04/2018] [Indexed: 12/31/2022] Open
Abstract
The central nervous system develops from monolayered neuroepithelial sheets. In a first step patterning mechanisms subdivide the seemingly uniform epithelia into domains allowing an increase of neuronal diversity in a tightly controlled spatial and temporal manner. In Drosophila, neuroepithelial patterning of the embryonic optic placode gives rise to the larval eye primordium, consisting of two photoreceptor (PR) precursor types (primary and secondary), as well as the optic lobe primordium, which during larval and pupal stages develops into the prominent optic ganglia. Here, we characterize a genetic network that regulates the balance between larval eye and optic lobe precursors, as well as between primary and secondary PR precursors. In a first step the proneural factor Atonal (Ato) specifies larval eye precursors, while the orphan nuclear receptor Tailless (Tll) is crucial for the specification of optic lobe precursors. The Hedgehog and Notch signaling pathways act upstream of Ato and Tll to coordinate neural precursor specification in a timely manner. The correct spatial placement of the boundary between Ato and Tll in turn is required to control the precise number of primary and secondary PR precursors. In a second step, Notch signaling also controls a binary cell fate decision, thus, acts at the top of a cascade of transcription factor interactions to define PR subtype identity. Our model serves as an example of how combinatorial action of cell extrinsic and cell intrinsic factors control neural tissue patterning.
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Affiliation(s)
| | | | - Cornelia Fritsch
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | - Boris Egger
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Simon G. Sprecher
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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