The pigmentary system of planaria

Abstract

The pigmentary system of the planaria, Dugesia gonocephala s.l. (Platyhelminthes, Turbellaria, Tricladida), has been studied by light and electron microscopy. The system consists of granules contained in chromatophore-like cells embedded in the parenchyma. The cell processes penetrate between the muscle layers and extend to the sub-epidermal basal lamina. The nature of the pigment and the comparative anatomical significance of the chromatophore structure is discussed.

Light-induced depigmentation in planarians models the pathophysiology of acute porphyrias

“…Strikingly, S. mediterranea homologs of ALAS, ALA dehydratase (ALAD ), and PBG deaminase (PBGD ), enzymes catalyzing the first 3 reactions in metazoan heme biosynthesis, were highly expressed in pigment cells, while the 5 remaining genes in the pathway were expressed predominantly or exclusively in other cell types ( Figure 4B ). In agreement with histological analyses of Dugesia gonocephala chromatophores ( Palladini et al, 1979 ), PBGD-1- expressing cells were located just beneath the epithelium ( Figure 4C ) and exhibited a dendritic morphology also characteristic of other pigment-producing cell types ( Figure 4D ). Double fluorescent in situ hybridization (dFISH) confirmed Smed-PBGD-1 (PBGD-1 ) was co-expressed with KMO-1 ( Figure 4E ).…”

FOX and ETS family transcription factors regulate the pigment cell lineage in planarians

“…Both dendritic and punctate markers were subepidermal, and interdigitated with muscle and epidermal progenitor cells (Fig. 2B), as predicted by previous electron microscopy studies of pigment cells in a related freshwater planarian species (Palladini et al, 1979). Interestingly, we observed a small but significant overlap between punctate and dendritic markers and early ( prog-1 + ) and late (AGAT-1 + ) epidermal progenitors (between ∼2% and 14%; Fig.…”

“…We favor the former model for several reasons. First, previous electron microscopy studies reported that mature pigment cells have a dendritic morphology in planarians (Palladini et al, 1979), as in many other animal species. Second, although there are clear differences in the number of cells expressing dendritic versus punctate markers during physiological cell turnover in adult animals (at the resolution of WISH), these markers show significant overlap (Fig.…”

“…After dFISH for dendritic pooled markers and punctate pooled markers, the same circles were overlaid (right of each pair) and cells identity and source of the ligand for this receptor are presently unknown, but it is interesting to speculate that it might be secreted by muscle, both because the pigment cells are interdigitated with the muscle layer (Fig. 2) (Palladini et al, 1979) and because many other patterning signals are secreted by muscle cells in planarians (Lander and Petersen, 2016;Scimone et al, 2016;Witchley et al, 2013).…”

Interaction of prion protein with divalent metals: possible role in neuroprotection and neurodegeneration in prion disease model

“…Inability of the pump to function properly results in excessive accumulation of copper in the body, causing cirrhosis and neurodegeneration (Harada et al 2000;La Fontaine et al 1998b;Langner and Denk 2004;Suzuki and Ogura 2000). Excessive copper also tends to accumulate in the basal ganglia of the brain, causing gliosis and neuronal loss similar to Parkinson's disease (Ferenci 2004;Palladini et al 1977;Tumer and Horn 1996; Yuzbasiyan-…”