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Specialized Cortex Glial Cells Accumulate Lipid Droplets in Drosophila melanogaster.

Kis V, Barti B, Lippai M, Sass M - PLoS ONE (2015)

Bottom Line: Although the central nervous system contains the highest relative amount and the largest number of different lipid species, neither the spatial nor the temporal distribution of LDs has been described.Superficial cortex glial cells, combined with subperineurial glial cells, express the Drosophila fatty acid binding protein (Dfabp), as we have demonstrated through light- and electron microscopic immunocytochemistry.To the best of our best knowledge this is the first study that describes LD neuroanatomy in the Drosophila larval brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary.

ABSTRACT
Lipid droplets (LDs) are common organelles of the majority of eukaryotic cell types. Their biological significance has been extensively studied in mammalian liver cells and white adipose tissue. Although the central nervous system contains the highest relative amount and the largest number of different lipid species, neither the spatial nor the temporal distribution of LDs has been described. In this study, we used the brain of the fruitfly, Drosophila melanogaster, to investigate the neuroanatomy of LDs. We demonstrated that LDs are exclusively localised in glial cells but not in neurons in the larval nervous system. We showed that the brain's LD pool, rather than being constant, changes dynamically during development and reaches its highest value at the beginning of metamorphosis. LDs are particularly enriched in cortex glial cells located close to the brain surface. These specialized superficial cortex glial cells contain the highest amount of LDs among glial cell types and encapsulate neuroblasts and their daughter cells. Superficial cortex glial cells, combined with subperineurial glial cells, express the Drosophila fatty acid binding protein (Dfabp), as we have demonstrated through light- and electron microscopic immunocytochemistry. To the best of our best knowledge this is the first study that describes LD neuroanatomy in the Drosophila larval brain.

No MeSH data available.


Related in: MedlinePlus

Ultrastructural features of the LD accumulating superficial cortical glial cells.(A) HRP-labeled superficial cortical glial cell (CG1), encapsulating a mitotic neuroblast (NB, arrows: chromosomes) and other neurons (N). Note the abundance of LDs. (A’) Same picture as shown in panel A but overexposed during acquisition to reveal the DAB stained processes (arrows) at low magnification. Note that a phagosome (ph, labeled in panel A) accumulates HRP. (B, B’) Higher magnification pseudocolored image taken from the dashed areas in panel A. DAB stained glial membranes are indicated (arrows). Two overlapping cortex glial processes (CG1 and CG2) insulate a mitotic neuroblast (NB). (C) Organization of the glial layers encapsulating neuroblasts. (C’) Subperineurial glial cells (SPG1-2) are connected to each other through septate junctions. (C”) A subperineurial (SPG2) and a superficial cortex glia (CG) are connected with an adherens junction. Scalebar: (A, A’, B) 1 μm, (B’,C, C’, C”) 100nm.
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pone.0131250.g004: Ultrastructural features of the LD accumulating superficial cortical glial cells.(A) HRP-labeled superficial cortical glial cell (CG1), encapsulating a mitotic neuroblast (NB, arrows: chromosomes) and other neurons (N). Note the abundance of LDs. (A’) Same picture as shown in panel A but overexposed during acquisition to reveal the DAB stained processes (arrows) at low magnification. Note that a phagosome (ph, labeled in panel A) accumulates HRP. (B, B’) Higher magnification pseudocolored image taken from the dashed areas in panel A. DAB stained glial membranes are indicated (arrows). Two overlapping cortex glial processes (CG1 and CG2) insulate a mitotic neuroblast (NB). (C) Organization of the glial layers encapsulating neuroblasts. (C’) Subperineurial glial cells (SPG1-2) are connected to each other through septate junctions. (C”) A subperineurial (SPG2) and a superficial cortex glia (CG) are connected with an adherens junction. Scalebar: (A, A’, B) 1 μm, (B’,C, C’, C”) 100nm.

Mentions: To verify our observations at the EM level, we labeled cortex glial membranes with a membrane-targeted HRP, which can be visualised after the DAB reaction [33]. As expected, we found that these superficial cortex glial cells insulated mitotic neuroblasts (Fig 4A). The cells accumulated high amounts of LDs in their perinuclear region, had invaginated dense heterochromatic nucleus and often also contained a high amount of glycogen. The cells were tightly attached to subperineurial cells. Another interesting finding that EM showed was that while neighbouring SPGs establish septate junctions (Fig 4C and 4C’), as reported previously [30], SPG and cortex glial cells were connected to each other through adherens junctions (Fig 4C and 4C”). Based on our light and electron microscopic observations, we concluded that the medial part of the central brain contains specialized superficial cortex glial cells that encapsulate NBs and contain the highest amount of LDs.


Specialized Cortex Glial Cells Accumulate Lipid Droplets in Drosophila melanogaster.

Kis V, Barti B, Lippai M, Sass M - PLoS ONE (2015)

Ultrastructural features of the LD accumulating superficial cortical glial cells.(A) HRP-labeled superficial cortical glial cell (CG1), encapsulating a mitotic neuroblast (NB, arrows: chromosomes) and other neurons (N). Note the abundance of LDs. (A’) Same picture as shown in panel A but overexposed during acquisition to reveal the DAB stained processes (arrows) at low magnification. Note that a phagosome (ph, labeled in panel A) accumulates HRP. (B, B’) Higher magnification pseudocolored image taken from the dashed areas in panel A. DAB stained glial membranes are indicated (arrows). Two overlapping cortex glial processes (CG1 and CG2) insulate a mitotic neuroblast (NB). (C) Organization of the glial layers encapsulating neuroblasts. (C’) Subperineurial glial cells (SPG1-2) are connected to each other through septate junctions. (C”) A subperineurial (SPG2) and a superficial cortex glia (CG) are connected with an adherens junction. Scalebar: (A, A’, B) 1 μm, (B’,C, C’, C”) 100nm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4493057&req=5

pone.0131250.g004: Ultrastructural features of the LD accumulating superficial cortical glial cells.(A) HRP-labeled superficial cortical glial cell (CG1), encapsulating a mitotic neuroblast (NB, arrows: chromosomes) and other neurons (N). Note the abundance of LDs. (A’) Same picture as shown in panel A but overexposed during acquisition to reveal the DAB stained processes (arrows) at low magnification. Note that a phagosome (ph, labeled in panel A) accumulates HRP. (B, B’) Higher magnification pseudocolored image taken from the dashed areas in panel A. DAB stained glial membranes are indicated (arrows). Two overlapping cortex glial processes (CG1 and CG2) insulate a mitotic neuroblast (NB). (C) Organization of the glial layers encapsulating neuroblasts. (C’) Subperineurial glial cells (SPG1-2) are connected to each other through septate junctions. (C”) A subperineurial (SPG2) and a superficial cortex glia (CG) are connected with an adherens junction. Scalebar: (A, A’, B) 1 μm, (B’,C, C’, C”) 100nm.
Mentions: To verify our observations at the EM level, we labeled cortex glial membranes with a membrane-targeted HRP, which can be visualised after the DAB reaction [33]. As expected, we found that these superficial cortex glial cells insulated mitotic neuroblasts (Fig 4A). The cells accumulated high amounts of LDs in their perinuclear region, had invaginated dense heterochromatic nucleus and often also contained a high amount of glycogen. The cells were tightly attached to subperineurial cells. Another interesting finding that EM showed was that while neighbouring SPGs establish septate junctions (Fig 4C and 4C’), as reported previously [30], SPG and cortex glial cells were connected to each other through adherens junctions (Fig 4C and 4C”). Based on our light and electron microscopic observations, we concluded that the medial part of the central brain contains specialized superficial cortex glial cells that encapsulate NBs and contain the highest amount of LDs.

Bottom Line: Although the central nervous system contains the highest relative amount and the largest number of different lipid species, neither the spatial nor the temporal distribution of LDs has been described.Superficial cortex glial cells, combined with subperineurial glial cells, express the Drosophila fatty acid binding protein (Dfabp), as we have demonstrated through light- and electron microscopic immunocytochemistry.To the best of our best knowledge this is the first study that describes LD neuroanatomy in the Drosophila larval brain.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary.

ABSTRACT
Lipid droplets (LDs) are common organelles of the majority of eukaryotic cell types. Their biological significance has been extensively studied in mammalian liver cells and white adipose tissue. Although the central nervous system contains the highest relative amount and the largest number of different lipid species, neither the spatial nor the temporal distribution of LDs has been described. In this study, we used the brain of the fruitfly, Drosophila melanogaster, to investigate the neuroanatomy of LDs. We demonstrated that LDs are exclusively localised in glial cells but not in neurons in the larval nervous system. We showed that the brain's LD pool, rather than being constant, changes dynamically during development and reaches its highest value at the beginning of metamorphosis. LDs are particularly enriched in cortex glial cells located close to the brain surface. These specialized superficial cortex glial cells contain the highest amount of LDs among glial cell types and encapsulate neuroblasts and their daughter cells. Superficial cortex glial cells, combined with subperineurial glial cells, express the Drosophila fatty acid binding protein (Dfabp), as we have demonstrated through light- and electron microscopic immunocytochemistry. To the best of our best knowledge this is the first study that describes LD neuroanatomy in the Drosophila larval brain.

No MeSH data available.


Related in: MedlinePlus