XB-ART-5164Gene Expr Patterns 2003 Jun 01;33:347-50. doi: 10.1016/s1567-133x(03)00032-2.
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The chloride conductance channel ClC-K is a specific marker for the Xenopus pronephric distal tubule and duct.
Almost nothing is known about the physiology of the pronephros other than that it is efficient at excreting large volumes of dilute urine. The distal segment of pronephric nephrons is the most poorly characterized region of this organ, in part due to the absence of early markers of this structure. In this report the embryonic expression of a Cl(-) conductance channel, x ClC-K, is described with high level transcription of this gene in the distal segment beginning at Xenopus stage 31. x ClC-K is also expressed at lower levels in the pronephric duct. This gene serves as a convenient marker for investigating the development of this physiologically critical nephric segment and also serves to identify the potential site of action of a component of the chloride handling system of the pronephros. As ClC-K channels are involved in human kidney disease the frog pronephros may be a useful system in which to study the in vivo activity of this channel.
PubMed ID: 12799083
Article link: Gene Expr Patterns
Species referenced: Xenopus
Genes referenced: clcnkb
Article Images: [+] show captions
|Fig. 1. xClC-K expression in the Xenopus pronephros. Twenty-five× (left) and 100× (right) images of the lateral pronephric region except where noted. (A, B) Stage 31. A faint ridge of staining in both distal tubule and duct is present, with duct staining being slightly stronger. Somite and head staining is background due to long development times. (C, D) Stage 34. Distal staining is now stronger than is duct. The red arrow indicates the point at which staining decreases. (E, F) Stage 38. (G, H) Stage 40. (I (dorsal), J) Stage 40.5.|
|Fig. 2. xClC-K expression in the distal segment and duct. All images depict transverse sections through stage 35 embryos previously stained in whole-mount for xClC-K expression with a purple substrate, then counterstained with eosin (pink). (A) Section through the pronephros. (B) Close up of panel A. Only distal tubules (DT) express xClC-K. The nephrostome (ns) and proximal tubule (PT) are not stained. (C) More posterior section through the pronephric duct. (D) Enlargement of panel C.|
|Stage 40-41 expression of clcnkb in laevis. Image not included in final published version|
|Stage 38 clcnkb expression. Panel F|