What triggers the gametocyte pathway in Plasmodium falciparum

Professor Emeritus William Trager passed away on Saturday 22 January, 2005. He would have celebrated his 95th birthday in March. Professor Trager had been working up to the day of his passing on yet another project, one that was just about completed.William Trager graduated with a BSc from Rutgers University (http://www.rutgers.edu/) and received a PhD from Harvard University (http://www.harvard.edu/). He spent his entire professional career at the Rockefeller University (http://www.rockefeller.edu/), where he became a Professor Emeritus in 1980 and remained active until the end of his life.Trager provided the first direct evidence of the importance of nutritional factors in host susceptibility to malaria. He established that intracellular parasites lack certain biosynthetic pathways and depend on their host cells for cofactors essential to their own metabolism. His laboratory provided the first demonstration of the fine-structural relationship between malaria parasites and their host RBCs. The laboratory also elucidated the cellular and physiological basis of the relative resistance to malaria conferred by the sickle hemoglobin gene. Trager and his coworkers achieved axenic cultivation of Plasmodium falciparum, obtaining extracellular development of the complete erythrocytic cycle.Other contributions included early studies of the nutritional needs of the larvae of Aedes aegypti (the yellow-fever vector), demonstration of the mechanism of acquired immunity to ticks and development of cultivation methods for a principal trypanosomal parasite of cattle.In 1976, Trager and a colleague described a practical method for the continuous cultivation of P. falciparum; this method has given rise to a spectrum of physiological, biochemical, immunological and genetic studies that was previously impossible or prohibitively difficult, paving the way for scientists working to develop an effective malaria vaccine. P. falciparum cultures have also advanced the work on malarial drug resistance and efforts to screen for new types of antimalarial compound.Trager received many honors, including Thailand's Prince Mahidol Award in Medical Science in 1994 (named in honor of the Thai Prince) for ‘exemplary contribution to the advancement of medicine in malaria’ (see http://kanchanapisek.or.th/pmaf/awardees/1994.en/).One of the prime leaders in malariology, William Trager was a talented, inspired, inspiring, insightful and honest scientist who will be missed by all who knew him (http://www.promedmail.org/pls/promed/f?p=2400:1202:8774933027688645908∷NO∷F2400_P1202_CHECK_DISPLAY,F2400_P1202_PUB_MAIL_ID:X,27869).