Prothoracicotropic hormone
Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen or an abdomen under diapause would induce molting or pupation. Thus, the brain was originally thought to be the source of the hormone that induces molting in insects.
Alma Joslyn Whiffen-Barksdale
In 1955, Barksdale became a Research Associate at the New York Botanical Garden and returned to the study of aquatic fungi. From 1955 to 1961, she expanded existing research on the species "Achlya bisexualis", focusing on the fungus' unique sexual reproductive hormones. It had been previously concluded by fellow mycologist, Dr.John Raper, that the development of sexual organs in "A. bisexualis" was mediated by the exchange of hormones between the male and female strains of the fungus. Over the course of 10 years of research, Dr. Barksdale discovered and isolated the sex hormone antheridiol: a steroid released by the female strains of "A. bisexualis", which stimulates the growth of antheridia when introduced to male strains of the fungus. Antheridiol also stimulates the release of a second hormone, when introduced to the male strains, which promoted the growth of oogonia in the female strains. Her discoveries sparked a new wave of interest in the Achlya genus as a research subject over the following decades, and she and Dr. Raper are jointly considered the primary establishing figures in "Achlya" research, according to the retrospective on her life published in the 1981 issue of "Achlya Newsletter."