Arne Christensen, PhD
Associate Professor of Biology
Anna Maria College
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Illustrations created for publications
Shown with corresponding reference and figure legend.

Image from (Christensen et al., 2018)

Model of the cladoceran F-actin bundles (red) in carapace epithelia as informed by confocal z-projections and orthogonal three-dimensional reconstructions. Pillar F-actin bundle stress fibers are predicted to merge at adherens junctions (pink) based on their structure in other species, but the presence of adherens junctions at cell-cell junctions within cladoceran pillars is entirely speculative. Membranous structures are in green, nuclei in blue, and carapace epithelia and cuticles are in grey.

Image from (McCormick et al., 2013)

Model for differential expression of NKAα1a and NKAα1b during smolt development. In freshwater (FW) parr and smolts, the gill epithelium is rich in ionocytes that express the freshwater NKA isoform, NKAα1a. In freshwater smolts, an additional class of ionocytes represented as an orange cell are present; these cells express NKAα1b or both NKAα1a and NKAα1b, as well as other ion transporters (CFTR and NKCC1) that are important for salt secretion. These NKAα1b-expressing ionocytes in freshwater smolts are likely to be inactive in freshwater but rapidly initiate salt secretion after exposure to seawater. AC, accessory cell.

Image from (Christensen et al., 2012)

Gill filament, lamellae and ionocytes in alewives. Diagrams indicate typical locations of ionocytes (red dots) and lamellae projecting above and below a gill filament, illustrating different section orientations used for localizing ionocytes by immunohistochemistry. LE, leading edge; TE, trailing edge. (A)  Exposure of across-filament structure with a sagittal section. (B) Exposure of along-filament structure with a transverse section. (C) Distribution of ionocytes across a gill filament in freshwater-acclimated (FW) and seawater-acclimated (SW) alewives. Images are representative 5 µm transverse sections, taken from proximal, medial and distal portions of the filament. LE, leading edge; TE, trailing edge. DAPI staining of cells (grey) indicates the filament and lamellae; fluorescence of antibody (red) indicates the location of ionocytes. In some cases, adjacent filaments were cropped from the image for clarity. A X25 objective was used; scale bar: 50 µm.

Image from (Christensen et al., 2012)

Summary of ion-transport protein localization in alewife ionocytes and a model for enhanced Na+ extrusion in seawater. Freshwater (FW) ionocytes express NKA, NHE3 and NKCC1 (possibly latent), whereas seawater (SW) ionocytes form clusters that are rich in NKA and NKCC1, express NHE3 and are frequently CFTR positive. Seawater ionocytes might share shallow Na+-permeable junctions with each other, as well as with accessory cells (AC), forming NKA-rich complexes with low Na+resistance to facilitate Na+ extrusion in seawater. PC, pavement cell; TJ, tight junction.

The following interactive Flash animations were developed as visual aids for describing complicated biochemical processes and tissue architecture.
Animations require Adobe Flash Player [download]
Freshwater- and Seawater-type Chloride Cell
Model of ion transport in gill chloride cells in seawater and freshwater, toggle within the animation by clicking the SW or FW buttons found in the upper corners of the image.
Grey - Chloride cell
Purple - Accessory cell

SW - Seawater-type chloride cell
CFTR - Cystic Fibrosis Transmembrane Conductance Regulator
NKA - Na+,K+-ATPase [alpha1b subunit]
NKCC - Na+-K+-2Cl-Cotransporter
Kir - inward rectifier K+ channel

FW - Freshwater-type chloride cell
AE - Anion Exchanger
V-HA - V-type H+-ATPase
ENaC - Epithelial Na+ Channel
NHE - Na+,H+ Exchanger
NCC - Na+-2Cl-Cotransporter
NKA - Na+,K+-ATPase [alpha1a subunit]

Download animated PowerPoint slide*:[ CCell.ppt] (150 KB)
Download Flash file:[ CCell - Flash]

* Insert slide into presentation, run animation by toggeling buttons, return to presention by clicking on periphery of slide.
PC only, ActiveX is not presently supported with Mac MS Office.
Cellular Architecture of the Vertebrate Retina
Retinal cells, click on the cell type within the diagram to identify it.
Site by: Arne Christensen, PhD
Anna Maria College
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Paxton, MA 01612