After half a century of work on the pineal gland, Jo Arendt‘s passing is a great scientific loss. Over these years Jo probably gave more melatonin talks than anyone else. Although her melatonin assay company is no longer, her indefatigable energy, prolific writings and intrepid explorations will continue to resonate. In the 1970s, there were just a few of us who tackled the challenge of developing an assay for circulating levels of melatonin. Since then, the field of human chronobiology has grown in no small part due to Jo and the talented investigators she trained (many are now leaders in the field).

Personally, I have many fond memories — taking walks together during conference breaks, preparing meals when staying at each other’s home and embarking on a post-meeting three-day visit to Iguazu Falls (just the two of us and our spouses).
 
Jo, I will miss you.