Distinct functions for IFT140 and IFT20 in opsin transport.

In the vertebrate retina, light is detected by the outer segments of photoreceptor rods and cones, which are highly modified cilia. Like other cilia, outer segments have no protein synthetic capacity and depend on proteins made in the cell body for their formation and maintenance. The mechanism of transport into the outer segment is not fully understood but intraflagellar transport (IFT) is thought to be a major mechanism for moving protein from the cell body into the cilium.

Disruption of Mks1 localization to the mother centriole causes cilia defects and developmental malformations in Meckel-Gruber syndrome.

Meckel-Gruber syndrome (MKS) is a recessive disorder resulting in multiple birth defects that are associated with mutations affecting ciliogenesis. We recovered a mouse mutant with a mutation in the Mks1 gene (Mks1(del64-323)) that caused a 260-amino-acid deletion spanning nine amino acids in the B9 domain, a protein motif with unknown function conserved in two other basal body proteins. We showed that, in wild-type cells, Mks1 was localized to the mother centriole from which the cilium was generated.

Scanning electron microscopy to examine cells and organs.

Scanning electron microscopy is an excellent method for viewing the surface of cells and organs, and provides exquisite detail of surface projections. This method has a long history of use in the analysis of eukaryotic cilia and flagella. In this chapter, we provide methods used by our group to examine mouse kidneys and the embryonic node.