Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Biochemistry, Biophysics and Molecular Biology


Neuroscience; Molecular, Cellular, and Developmental Biology;

First Advisor

Jorgen Johansen

Second Advisor

Kristen M. Johansen


This thesis describes the molecular and functional analysis of the leech Hillarin and its Drosophila homolog D-hil. Leech Hillarin was identified by screening a leech expression library with the mAb Lan3-15, which specifically labels the axon hillock region of leech neurons. Database searches revealed that leech Hillarin has a number of potential homologs in a variety of organisms such as yeast, cyanobacterium, fly, nematode, mouse and human and that these proteins share two novel protein domains, the W180 domain and the H domain. The W180 domain is enriched with tryptophans whereas the H domain shares high number of invariant residues among family members and was named since it was first described in Hillarin. Drosophila member of this protein family, D-hil, is localized to the neuropil of central nervous system neurons, the cortex of metaphase S2 cells, and the cleavage furrow of dividing S2 cells. The protein level of D-hil starts to increase 12 hours after egg laying and the expression persists into adult stage, indicating the expression of D-hil is developmentally regulated. Pnut, a Drosophila septin member, was identified as an interactor of D-hil. The interaction is supported by the co-immunoprecipitation and co-localization results. Furthermore, GFP-D-hil in transfected S2 cells co-localizes with Pnut and F-actin. Genetic interaction studies between a mutant Pnut allele and a mutant D-hil allele suggest that they function in the same genetic pathway since D-hilPnut double mutants show double amount of polyploid cells in the third instar larval brains compared to that of the Pnut single mutants. This genetic interaction between D-hil and Pnut further supports their interaction in vivo.



Digital Repository @ Iowa State University,

Copyright Owner

Yun Ji



Proquest ID


File Format


File Size

93 pages