Research

I feel extremely lucky to have had the opportunity to explore a wide diversity of topics that have excited my interest. Below are vignettes of some of the major research projects I have been or am currently involved in.

You can hover over the paper text at the end of paragraphs for more information on relevant publications.

Development of biomarkers for assessing health and physiology in population-based research

PI: J Josh Snodgrass

Biomarkers can provide objective measures of health, facilitate the identification of physiological mechanisms through which humans adapt to environmental stressors, and allow mapping of the processes through which social and cultural factors ‘get under the skin’ to shape human development, behavior, and health.

In particular, minimally invasive techniques have allowed unprecedented access to previously unstudied or unstudied populations. Although saliva and urine samples have been used to access certain biomarkers, blood is the biological substance of choice or necessity for many analytes.

Blood from a finger prick collected onto filter paper (dried blood spots) has opened a realm of possibilities, and the last decade has seen the adoption of this method in biological anthropology, epidemiology, psychology, and a variety of other disciplines.

In my role as lab manager of the Snodgrass Human Biology Research Lab, I am actively engaged in developing and validating new, minimally invasive molecular biology-based techniques (primarily ELISAs) for research in our lab and for dissemination to other researchers interested in assessing human health and physiology in a population-based context (paper).

Evolution of steroid receptors

PI: Joe Thornton

Steroid hormone receptors (SRs), such as the estrogen receptor and androgen receptor, are hormone-activated nuclear transcription factors with diverse and largely distinct specificities for steroid hormones (e.g. estrogen and testosterone).

The SR family diversified from a single gene through a series of gene duplication events early during chordate and vertebrate evolution, and the duplicate copies diversified to bind steroid hormones distinct from one another (paper).

I used a synthesis of phylogenetic, ancestral gene resurrection, structural biology, and molecular biology approaches to reconstruct historical changes in ligand recognition in the SR family (paper).

In addition, in collaboration with colleagues, I showed how only two mutations were sufficient to switch the specificity of the ancestral steroid receptor and allow it to recognize a new class of steroid hormones, due to amplification of the effects of these two mutations by the protein’s architecture (paper & media coverage).

Bat phylogenetics

PIs: David Jacobs & Conrad Matthee

Bats, the only mammals capable of powered flight and sophisticated laryngeal echolocation, are one of the most species-rich and ubiquitous orders of mammals.

However, evolutionary relationships within this group were poorly resolved and controversial when my colleagues (Prof David Jacobs, Prof Conrad Matthee) and I initiated this study in 2003. I generated a robust  phylogenetic tree of  Chiroptera to evaluate echolocation within Chiroptera as well as gain insight to their biogeographical history by generating sequence data from four nuclear intron markers for multiple representatives of 17 of the 18 recognized extant bat families (paper).

This allowed me to confirm the then-controversial hypothesis that some families of insect-eating microbats were more closely related to fruit bats than to the other microbats. In addition, diversification of bats was dated to the Cretaceous-Tertiary boundary (65 mya), and the data suggested that bats originated and dispersed out of Africa.

Mapping of morphological characters and echolocation onto the molecular phylogeny I generated provided some support for the hypothesis that echolocation may have evolved twice within the bats. In the process of collecting bat tissue samples for this project, we also discovered the existence of a new species of bat in South Africa (paper).

Publications

I have published in a broad range of peer-reviewed scientific journals, reflecting my diverse research interests. You can read more about my publications here.

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