scholarly journals Survival of photoreceptor neurons in the compound eye of Drosophila depends on connections with the optic ganglia

Development ◽  
1992 ◽  
Vol 114 (2) ◽  
pp. 355-366 ◽  
Author(s):  
A.R. Campos ◽  
K.F. Fischbach ◽  
H. Steller
Keyword(s):  
Trophic Interactions ◽  
Compound Eye ◽  
Normal Development ◽  
Optic Lobe ◽  
Photoreceptor Cells ◽  
Optic Lobes ◽  
Genetic Mosaic ◽  
Retinal Innervation ◽  
Photoreceptor Neurons ◽  
The Brain

The importance of retinal innervation for the normal development of the optic ganglia in Drosophila is well documented. However, little is known about retrograde effects of the optic lobe on the adult photoreceptor cells (R-cells). We addressed this question by examining the survival of R-cells in mutant flies where R-cells do not connect to the brain. Although imaginal R-cells develop normally in the absence of connections to the optic lobes, we find that their continued survival requires these connections. Genetic mosaic studies with the disconnected (disco) mutation demonstrate that survival of R-cells does not depend on the genotype of the eye, but is correlated with the presence of connections to the optic ganglia. These results suggest the existence of retrograde interactions in the Drosophila visual system reminiscent of trophic interactions found in vertebrates.

A new rhodopsin in R8 photoreceptors of Drosophila: evidence for coordinate expression with Rh3 in R7 cells

Development ◽  
1997 ◽  
Vol 124 (9) ◽  
pp. 1665-1673 ◽  
Author(s):  
D. Papatsenko ◽  
G. Sheng ◽  
C. Desplan
Keyword(s):  
Concerted Evolution ◽  
Compound Eye ◽  
Photoreceptor Cells ◽  
Opsin Gene ◽  
Primary System ◽  
Neighboring Cell ◽  
Coordinate Expression ◽  
Opsin Genes ◽  
Developmental Signaling ◽  
The Brain

The photoreceptor cells of the Drosophila compound eye are precisely organized in elementary units called ommatidia. The outer (R1-R6) and inner (R7, R8) photoreceptors represent two physiologically distinct systems with two different projection targets in the brain (for review see Hardie, 1985). All cells of the primary system, R1-R6, express the same rhodopsin and are functionally identical. In contrast, the R7 and R8 photoreceptors are different from each other. They occupy anatomically precise positions, with R7 on top of R8. In fact, there are several classes of R7/R8 pairs, which differ morphologically and functionally and are characterized by the expression of one of two R7-specific opsins, rh3 or rh4. Here, we describe the identification of a new opsin gene, rhodopsin 5, expressed in one subclass of R8 cells. Interestingly, this subclass represents R8 cells that are directly underneath the R7 photoreceptors expressing rh3, but are never under those expressing rh4. These results confirm the existence of two subpopulations of R7 and R8 cells, which coordinate the expression of their respective rh genes. Thus, developmental signaling pathways between R7 and R8 lead to the exclusive expression of a single rhodopsin gene per cell and to the coordinate expression of another one in the neighboring cell. Consistent with this, rh5 expression in R8 disappears when R7 cells are absent (in sevenless mutant). We propose a model for the concerted evolution of opsin genes and the elaboration of the architecture of the retina.

VI. On the structure of the optic lobes of the Cuttle-fish

1867 ◽  
Vol 15 ◽  
pp. 260-261
Keyword(s):  
Optic Lobe ◽  
Thick Layer ◽  
Human Kidney ◽  
The Other ◽  
Optic Nerves ◽  
Optic Lobes ◽  
Striking Resemblance ◽  
Dark Layer ◽  
Outer Portion ◽  
The Brain

The brain of the Cuttle-fish consists of several ganglia closely aggregated around the upper part of the œsophagus. The foremost or pharyngeal ganglion, which is much the smallest, is bilobed and somewhat quadrangular. The next is a large bilobed ganglion which forms the roof of the canal for the œsophagus. Beneath the œsophagus is another large and broad mass, which is connected on each side with the supra-œsopbageal masses by bands that complete the oesophageal ring. From each side of the cephalic masses springs a thick optic peduncle which ends in the optic lobe. Each optic lobe is larger than all the other cerebral masses taken together, and has a striking resemblance in shape to the human kidney. It is completely enveloped in a thick layer of optic nerves disposed in flattened bands which issue from all parts of its substance and proceed to the back of the eye in a fan-like expansion, the upper and lower bands crossing each other in their course. The substance of each lobe consists of two distinct portions, which differ from each other. entirely in appearance. The outer portion resembles a very thin rind or shell, is extremely delicate, and very easily torn from the central substance which it encloses. It consists of three concentric layers—an external dark layer, an internal dark layer, and a middle pale and broader layer containing thin and concentric bands of fibres.

Expression of the Drosophila optomotor-blind gene transcript in neuronal and glial cells of the developing nervous system

Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 1017-1029 ◽  
Author(s):  
B. Poeck ◽  
A. Hofbauer ◽  
G.O. Pflugfelder
Keyword(s):  
Nervous System ◽  
Embryonic Development ◽  
Optic Lobe ◽  
Adult Brain ◽  
Gene Transcript ◽  
Larval Brain ◽  
Ventral Ganglion ◽  
Optic Lobes ◽  
Central Brain ◽  
The Brain

Mutations in the complex gene locus optomotor-blind (omb) can lead to defects in the development of both the optic lobes and external features of the adult fly. We describe here the expression of omb in the developing and adult nervous system using in situ hybridization. During embryogenesis, omb expression is first observed in the optic lobe anlagen. It later expands to a larger part of the developing larval brain and to the gnathal lobes. Cells in the ventral and peripheral nervous systems begin to express omb after completion of germ band extension. Later in embryonic development, expression declines and only persists in the antennomaxillary complex and in part of the brain hemispheres. During the larval and pupal stages, omb expression in the brain is confined to the developing optic lobes and contiguous regions of the central brain. At these stages, only a few cells show expression in the ventral ganglion. In the eye imaginal disc, transcript accumulation is most conspicuous in a group of presumptive glia precursor cells posterior to the morphogenetic furrow and in the optic stalk. In the adult brain, expression is prominent in several regions of the optic lobe cortex and along the border between central brain and optic lobes. In the mutation In(1)ombH31, 40 kb of regulatory DNA, downstream from the transcription unit, are removed from the omb gene. In(1)ombH31 is characterized by the lack of a set of giant interneurons from the lobula plate of the adult optic lobes. We find that, already during embryogenesis, there is a drastic difference between wild type and In(1)ombH31 in the level of the omb transcript in the optic lobe primordia. The adult mutant phenotype may thus be caused by omb misexpression during embryonic development.

Localization of the clock controlling circadian rhythms in the first neuropile of the optic lobe in the housefly

2001 ◽  
Vol 204 (19) ◽  
pp. 3303-3310
Author(s):  
Monika Bałys ◽  
Elżbieta Pyza
Keyword(s):  
Circadian Rhythms ◽  
Musca Domestica ◽  
Compound Eye ◽  
Optic Lobe ◽  
Continuous Light ◽  
Constant Darkness ◽  
Cross Sectional ◽  
Circadian Oscillators ◽  
L1 And L2 ◽  
The Brain

SUMMARYThe visual system of a fly expresses several circadian rhythms that have been detected in the photoreceptors of the compound eye and in the first neuropile, the lamina, of the underlying optic lobe. In the lamina, axons of two classes of interneuron, L1 and L2, exhibit cyclical size changes, swelling by day and shrinking by night. These rhythmic size changes may be generated by circadian oscillators located inside and/or outside the optic lobe. To localize such oscillators, we have examined changes in the axonal cross-sectional areas of L1 and L2 within the lamina of the housefly (Musca domestica) under conditions of 12 h of light and 12 h of darkness (LD12:12), constant darkness (DD) or continuous light (LL) 24 h after the medulla was severed from the rest of the brain. After the lesion, the axon size changes of L1 and L2 were maintained only in LD conditions, but were weaker than in control flies. In DD and LL conditions, they were eliminated. This indicates that circadian rhythms in the lamina of a fly are generated central to the lamina and medulla neuropiles of the optic lobe. Cyclical changes of light and darkness in LD conditions are still able, however, to induce a weak daily rhythm in the axon sizes of L1 and L2.

Actin and α-tubulin immuno-EM labelings reveal differences in intra versus interphotoreceptor matrix

1990 ◽  
Vol 48 (3) ◽  
pp. 466-467
Author(s):  
Matti Järvilehto ◽  
Riitta Harjula
Keyword(s):  
Compound Eye ◽  
Frozen Section ◽  
Smooth Muscle Actin ◽  
Photoreceptor Cells ◽  
Immune Serum ◽  
Cell Organelles ◽  
Calliphora Erythrocephala ◽  
Optical Axes ◽  
Interphotoreceptor Matrix ◽  
Similar Kind

The photoreceptor cells in the compound eyes of higher diptera are clustered in groups (ommatidia) of eight receptor cells. The cells from six adjacent ommatidia are organized into optical units, neuro-ommatia sharing the same visual field. In those ommatidia the optical axes of the photopigment containing structures (rhabdomeres) are parallel. The rhabdomeres of the photoreceptor cells are separated from each other by an interstitial i.e innerommatidial space (IOS). In the photoreceptor cell body, besides of the normal cell organelles, a cellular matrix is a structurally apparent component. Similar kind of reticular formation is also found in the IOS containing some unidentified filamentary substance, of which composition and functional significance for optical properties of vision is the aim of this report.The prefixed (2% PA + 0.2% GA in 0.1-n phosphate buffer, pH 7.4, for 1h), frozen section blocks of the compound eye of the blowfly (Calliphora erythrocephala) were prepared by immuno-cryo-techniques. The ultrathin cryosections were incubated with antibodies of monoclonal α-tubulin and polyclonal smooth muscle actin. Control labelings of excess of antigen, non-immune serum and non-present antibody were perforated.

A study of the properties, morphogenetic potencies and prospective fate of outer and inner layers of ectodermal and chordamesodermal regions during gastrulation, in various Anuran amphibians

Development ◽  
1983 ◽  
Vol 75 (1) ◽  
pp. 67-86
Author(s):  
T. A. Dettlaff
Keyword(s):  
Outer Layer ◽  
Normal Development ◽  
Neural Plate ◽  
Ependymal Cells ◽  
Epithelial Layer ◽  
Bombina Bombina ◽  
Cell Layers ◽  
The Brain ◽  
Early Gastrula

In both the ectodermal and the chordamesodermal regions of Anuran embryos, the outer layer of cells possesses epithelial properties and has the same restricted morphogenetic potencies. It is thus interchangeable between the regions, capable of epiboly and, when underlain by notochord material, of the formation of bottle-shaped cells as at the blastoporal groove, and invagination. When taken from the chordamesoderm region, this outer layer has no inducing effect on the ectoderm of the early gastrula. In normal development the outer layer of the neural plate takes an active part in forming the neural tube cavity. It gives rise to the neuroepithelial roof of the diencephalon and medulla oblongata and, when underlain by neuroblasts that develop from the inner cell layers, to ependymal cells of the brain wall. The outer layer of the notochord material is included in the epithelial layer underlying the roof of the gastrocoel - the hypochordal plate. The inner layers of these regions consist of loosely arranged cells and normally have no epithelial properties although, when taken from the ectoderm region, they may acquire such properties upon long-term contact with the environment. However they have wide morphogenetic potencies; the differences in these potencies between cells taken from the various presumptive regions being less than the differences between outer and inner cell layers in each region. Maps are provided which show the arrangement of presumptive rudiments in the ectoderm and chordamesoderm on sagittal sections through Bombina bombina embryos in early and late gastrulation.

Ultrastructure and synaptic relations in the optic lobe of the brain of Eledone and Octopus

1972 ◽  
Vol 39 (1-2) ◽  
pp. 115-123 ◽  
Author(s):  
Norman M. Case ◽  
E.G. Gray ◽  
J.Z. Young
Keyword(s):  
Optic Lobe ◽  
The Brain

Distribution of the myosin I-like ninaC proteins in the Drosophila retina and ultrastructural analysis of mutant phenotypes

1992 ◽  
Vol 101 (1) ◽  
pp. 247-254 ◽  
Author(s):  
J.L. Hicks ◽  
D.S. Williams
Keyword(s):  
Compound Eye ◽  
Photoreceptor Cells ◽  
Amino Acid Sequences ◽  
Ultrastructural Analysis ◽  
Multivesicular Bodies ◽  
Filamentous Actin ◽  
Electron Microscopic ◽  
Myosin I ◽  
Specific Proteins ◽  
Mutant Phenotypes

The Drosophila ninaC gene encodes for two head-specific proteins of 132 kDa and 174 kDa. Their predicted amino acid sequences indicate that they may have myosin I and kinase properties. We have: (1) determined the cellular and subcellular distributions of the ninaC proteins in the Drosophila retina by electron microscopic immunocytochemistry with an antibody specific for epitopes shared by both proteins; (2) characterized the ultrastructure of the mutant phenotype. The proteins were detected only in the photoreceptor cells, but were detected in all classes of the compound eye photoreceptors. Within the photoreceptors, they were found in the rhabdomeral microvilli and the cytoplasm adjacent to the rhabdomeres. This distribution coincides with that shown previously for actin filaments. Immunolabelling of tissue from the ninaC P221 mutant, which lacks the 174 kDa protein, and two mutants whose rhabdomeres degenerate, suggests that the 132 kDa protein is present primarily in the cytoplasm adjacent to the rhabdomeres, and that the 174 kDa protein is concentrated in the rhabdomeres. Our ultrastructural analysis showed that the axial cytoskeleton of the rhabdomeral microvilli (which contains filamentous actin) was absent in both the null and P221 mutants. In the photoreceptor cell cytoplasm, the number of multivesicular bodies in the null mutant, but not the P221 mutant, was 3-fold greater in comparison with wild-type.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Brain manganese and the balance between essential roles and neurotoxicity

2020 ◽  
Vol 295 (19) ◽  
pp. 6312-6329 ◽  
Author(s):  
Rekha C. Balachandran ◽  
Somshuvra Mukhopadhyay ◽  
Danielle McBride ◽  
Jennifer Veevers ◽  
Fiona E. Harrison ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Normal Development ◽  
The Body ◽  
Neurological Dysfunction ◽  
Cellular Transport ◽  
Brain Health ◽  
Biochemical Mechanisms ◽  
Molecular And Biochemical Mechanisms ◽  
Neuronal Physiology ◽  
The Brain

Manganese (Mn) is an essential micronutrient required for the normal development of many organs, including the brain. Although its roles as a cofactor in several enzymes and in maintaining optimal physiology are well-known, the overall biological functions of Mn are rather poorly understood. Alterations in body Mn status are associated with altered neuronal physiology and cognition in humans, and either overexposure or (more rarely) insufficiency can cause neurological dysfunction. The resultant balancing act can be viewed as a hormetic U-shaped relationship for biological Mn status and optimal brain health, with changes in the brain leading to physiological effects throughout the body and vice versa. This review discusses Mn homeostasis, biomarkers, molecular mechanisms of cellular transport, and neuropathological changes associated with disruptions of Mn homeostasis, especially in its excess, and identifies gaps in our understanding of the molecular and biochemical mechanisms underlying Mn homeostasis and neurotoxicity.

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