Complex sentence: While at Harvard, Gibbs switched advisors, completing her PhD under the advisement of George Chapman, studying the pyrenoid structure in algae, as well as the ultrastructure of the chloroplast itself.
Split into simpler sentences: While at Harvard, Gibbs switched advisors, completing her PhD under the advisement of George Chapman. During her tenure in Chapman's lab, Gibbs studied the pyrenoid structure in algae, as well as the ultrastructure of the chloroplast itself.