The Caenorhabditis elegans lin-15 locus

Author: Huang, Linda S.

Year: 1995

Degree: Dissertation (Ph.D.)

Advisor: Sternberg, Paul W.

Committee Members: Sternberg, Paul W.; Anderson, David J.; Meyerowitz, Elliot M.; Davidson, Eric H.; Zinn, Kai George

Option: Biology

DOI: 10.7907/pat7-8d95

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

In the nematode [...], vulval development involves an inductive signalling event mediated by the LIN-3 growth factor and the LET-23 receptor tyrosine kinase. The LIN-3 growth factor is sent from the anchor cell, a cell in the somatic gonad, to the six multipotent vulval precursor cells (VPCs) in the ventral epidermis. Lack of the signal leads to none of the six VPCs adopting vulval fates. The [...] locus is a negative regulator of [...] mediated signalling; animals carrying loss-of function mutations in [...] have excessive vulval differentiation. Mosaic studies demonstrate this negative regulation to occur non-autonomously. Furthermore, the [...] locus has two genetically defined functions, A and B. These A and B functions are shared by other loci with these functions, defining two distinct pathways for negative regulation. The A and B functions are redundant because animals defective in only one function display the wild-type phenotype; only animals defective in both A and B function display the excessive vulval differentiation phenotype.

This thesis describes the molecular and genetic analysis of the [...]

locus. The lin-15 locus was cloned based on its genetic map position. The two functions of lin-15 are due to two transcripts comprising the [...] locus, one transcript corresponding to the A function, the other, the B function. These two transcripts are transcribed in the same direction, separated by 105 base pairs, and possibly transcribed polycistronically. The predicted proteins coded for by both transcripts are novel and hydrophilic. Antibodies raised against the LIN-15B protein show that LIN-15B is a 170 kD protein that is localized to the nucleus and broadly expressed. Genetic studies demonstrate that [...] acts upstream of the receptor and in parallel to the inductive signal. When a [...] null allele is used to modulate signalling through weakly functioning LET-23 receptors, we see that the activity of the receptor can be correlated to the type of vulval fate specified.

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