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Heterogeneous generation of new cells in the adult echinoderm nervous system.

Mashanov VS, Zueva OR, García-Arrarás JE - Front Neuroanat (2015)

Bottom Line: Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline.Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals.Further analysis of one of those genes, the transcription factor Myc, showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Puerto Rico Rio Piedras, PR, USA.

ABSTRACT
Adult neurogenesis, generation of new functional cells in the mature central nervous system (CNS), has been documented in a number of diverse organisms, ranging from humans to invertebrates. However, the origin and evolution of this phenomenon is still poorly understood for many of the key phylogenetic groups. Echinoderms are one such phylum, positioned as a sister group to chordates within the monophyletic clade Deuterostomia. They are well known for the ability of their adult organs, including the CNS, to completely regenerate after injury. Nothing is known, however, about production of new cells in the nervous tissue under normal physiological conditions in these animals. In this study, we show that new cells are continuously generated in the mature radial nerve cord (RNC) of the sea cucumber Holothuria glaberrima. Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline. Some of the new cells generated in the apical region of the ectoneural neuroepithelium leave their place of origin and migrate basally to populate the neural parenchyma. Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals. Further analysis of one of those genes, the transcription factor Myc, showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms.

No MeSH data available.


Related in: MedlinePlus

Expression of homologs of neural stem/progenitor cell maintenance genes in the adult radial nerve cord (RNC) of H. glaberrima. The left column (A–G) shows reference low magnification micrographs of the entire cross section profile of the RNC. The middle column (A′–G′) is a detailed view of the midline region of the ectoneural neuroepithelium. Micrographs in the right column (A″–G″) are higher magnification of the lateral region of the ectoneural neuroepithelium.
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Figure 4: Expression of homologs of neural stem/progenitor cell maintenance genes in the adult radial nerve cord (RNC) of H. glaberrima. The left column (A–G) shows reference low magnification micrographs of the entire cross section profile of the RNC. The middle column (A′–G′) is a detailed view of the midline region of the ectoneural neuroepithelium. Micrographs in the right column (A″–G″) are higher magnification of the lateral region of the ectoneural neuroepithelium.

Mentions: We then employed in situ hybridization in order to investigate spatial expression of the above genes at the tissue level in the adult sea cucumber RNC (Figures 4–6). All 16 genes are strongly and extensively expressed in the apical region of the ectoneural neuroepithelium. However, this expression domain is discontinuous, as a narrow band of midline cells shows no positive staining with any of the riboprobes used in this study. In addition to being expressed in the apical region of the neuroepithelium, ten of the above genes, including Hes, Klf1/2/4, Myc, SoxB1, Piwi, NFI, DCLK, Prox, Runt, and Lhx1/5 are also expressed in scattered cells in the neural parenchyma. The labeled parenchymal cells are most abundant in the lateral regions of the RNC and are rare in the midline region (see e.g., Figures 4C,D,G,G″, 6A,A″,F,F″).


Heterogeneous generation of new cells in the adult echinoderm nervous system.

Mashanov VS, Zueva OR, García-Arrarás JE - Front Neuroanat (2015)

Expression of homologs of neural stem/progenitor cell maintenance genes in the adult radial nerve cord (RNC) of H. glaberrima. The left column (A–G) shows reference low magnification micrographs of the entire cross section profile of the RNC. The middle column (A′–G′) is a detailed view of the midline region of the ectoneural neuroepithelium. Micrographs in the right column (A″–G″) are higher magnification of the lateral region of the ectoneural neuroepithelium.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585025&req=5

Figure 4: Expression of homologs of neural stem/progenitor cell maintenance genes in the adult radial nerve cord (RNC) of H. glaberrima. The left column (A–G) shows reference low magnification micrographs of the entire cross section profile of the RNC. The middle column (A′–G′) is a detailed view of the midline region of the ectoneural neuroepithelium. Micrographs in the right column (A″–G″) are higher magnification of the lateral region of the ectoneural neuroepithelium.
Mentions: We then employed in situ hybridization in order to investigate spatial expression of the above genes at the tissue level in the adult sea cucumber RNC (Figures 4–6). All 16 genes are strongly and extensively expressed in the apical region of the ectoneural neuroepithelium. However, this expression domain is discontinuous, as a narrow band of midline cells shows no positive staining with any of the riboprobes used in this study. In addition to being expressed in the apical region of the neuroepithelium, ten of the above genes, including Hes, Klf1/2/4, Myc, SoxB1, Piwi, NFI, DCLK, Prox, Runt, and Lhx1/5 are also expressed in scattered cells in the neural parenchyma. The labeled parenchymal cells are most abundant in the lateral regions of the RNC and are rare in the midline region (see e.g., Figures 4C,D,G,G″, 6A,A″,F,F″).

Bottom Line: Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline.Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals.Further analysis of one of those genes, the transcription factor Myc, showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Puerto Rico Rio Piedras, PR, USA.

ABSTRACT
Adult neurogenesis, generation of new functional cells in the mature central nervous system (CNS), has been documented in a number of diverse organisms, ranging from humans to invertebrates. However, the origin and evolution of this phenomenon is still poorly understood for many of the key phylogenetic groups. Echinoderms are one such phylum, positioned as a sister group to chordates within the monophyletic clade Deuterostomia. They are well known for the ability of their adult organs, including the CNS, to completely regenerate after injury. Nothing is known, however, about production of new cells in the nervous tissue under normal physiological conditions in these animals. In this study, we show that new cells are continuously generated in the mature radial nerve cord (RNC) of the sea cucumber Holothuria glaberrima. Importantly, this neurogenic activity is not evenly distributed, but is significantly more extensive in the lateral regions of the RNC than along the midline. Some of the new cells generated in the apical region of the ectoneural neuroepithelium leave their place of origin and migrate basally to populate the neural parenchyma. Gene expression analysis showed that generation of new cells in the adult sea cucumber CNS is associated with transcriptional activity of genes known to be involved in regulation of various aspects of neurogenesis in other animals. Further analysis of one of those genes, the transcription factor Myc, showed that it is expressed, in some, but not all radial glial cells, suggesting heterogeneity of this CNS progenitor cell population in echinoderms.

No MeSH data available.


Related in: MedlinePlus