The Molecular and Genomic Evolution of the Relaxin Gene Cluster in Hominoid Primates

Defense Date

7-13-2007

Graduation Date

Summer 1-1-2007

Availability

Restricted

Submission Type

thesis

Degree Name

MS

Department

Biological Sciences

Committee Chair

Michael Jensen-Seaman

Committee Member

Brady Porter

Committee Member

Kyle Selcer

Keywords

Relaxin, parturition, human evolution, labor, hominoid, selection

Abstract

Relaxin is a peptide hormone expressed during pregnancy whose function is to degrade connective tissue at the pubic symphysis and soften the cervix in preparation for birth. During evolution, the expansion of the human brain created a problem unique among hominoids: passage of a large fetal skull through a pelvic inlet designed for bipedal locomotion. Relaxin may have evolved to play a key role in the adaptations necessary to solve this problem. Humans and the great apes possess the relaxin cluster, consisting of RLN1, RLN2 and INSL4. Comparative analyses were used to examine the mode of sequence evolution in these genes, in order to test the hypothesis that positive selection has driven their evolution. Since this cluster arose as the result of multiple duplication events, we determined the number of putatively functional relaxin genes in each species in the study and characterized gene conversion events in the hominoids. Lastly, comparative computational analysis of regulatory elements critical for expression of the relaxin genes were evaluated for changes that might alter the expression pattern of both genes. Observed changes in regulatory elements have been interpreted in a phylogenetic context, and under the hypothesis that evolution of the relaxin promoter regions may be responsible for adaptations related to human birth.

Format

PDF

Language

English

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