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Jeremiah Hackett, 2006-2007 Postdoctoral Scholar

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Jeremiah Hackett

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CICOR postdoctoral scholar Jeremiah Hackett, right, works with Amy Koid, a summer student fellow in Don Anderson's lab. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)

Dr. Hackett arrived at the Woods Hole Oceanographic Institution (WHOI) in September of 2005, after completing his Ph.D. in genetics at the University of Iowa.  During his Ph.D. training, Dr. Hackett generated a genomic resource for the toxic dinoflagellate Alexandrium tamarense and used these data to address plastid evolution in dinoflagellates.  Dr. Hackett’s Ph.D. training provided him with a strong background in genomics, molecular biology and evolution.  At WHOI, Dr. Hackett seeks to become familiar with the ecology and physiology of toxic dinoflagellates and apply genomic tools to investigate harmful algal bloom formation.  Dr. Hackett’s project at WHOI, in collaboration with faculty advisor Donald M. Anderson, is to use this genomic resource to investigate the ecology of harmful algal bloom formation and toxin production in Alexandrium species, which cause paralytic shellfish poisoning through the production of saxitoxin.

Dr. Hackett’s primary project is to use the expressed sequence tag (EST) database that he generated in his Ph.D. to identify genes involved in nutrient utilization (i.e. nitrogen and phosphorus) and toxin production.  The ESTs are partial sequences of expressed genes in Alexandrium are an efficient means for the discovery of genes involved in these processes.  He is then measuring the expression of these genes in cultures of Alexandrium grown under nutrient stress.  This work will identify genes that may serve as markers for nutrient stress in natural toxic blooms.  Samples from a natural bloom were also collected for gene expression analysis.  The ultimate goal of this research is to identify a set of genes that can be used as markers of nutrient stress and toxin production to analyze how nutrient utilization influences the growth, sustenance, and decline of harmful algal blooms.  Dr. Hackett hopes to use these markers as a diagnostic “tool kit” that can be used to monitor blooms and predict their severity and toxicity in the field.

Using bioinformatics tools, Dr. Hackett identified genes in Alexandrium involved in nitrogen (e.g. nitrate reductase, glutamine synthetase, urease) and phosphorus (alkaline phosphatase, phosphate transporters) utilization.  The expression of these genes was tested on cultures of Alexandrium under nitrogen and phosphorus stress and compared to the nutrient replete condition using quantitative polymerase chain reaction (QPCR).  These experiments confirmed that the expression of these genes responds to decreasing nutrient levels.  Dr. Hackett also tested several genes that may be directly involved in toxin production, although clear candidates have yet to be identified.  Dr. Hackett and colleagues from the Anderson lab collected samples of a toxic Alexandrium bloom from Salt Pond in Eastham, MA from April-June 2006.  Candidate markers for nutrient stress are currently being tested on these field samples.  The QPCR method needs to be optimized before it will be clear if these genes will be good candidates to monitor the nutrient status of natural algal blooms.

Dr. Hackett is also attempting to culture another harmful dinoflagellate, Dinophysis, which is the cause of diarrhetic shellfish poisoning (DSP).  Research into the causes of has been hindered by the fact researchers are currently unable to keep this organism alive in culture.  Previous work by Dr. Hackett and others, using molecular biology techniques, has shown that Dinophysis steals its chloroplast from another alga, a cryptophyte called Teleaulax.  In an attempt to culture Dinophysis, Dr. Hackett isolated single cells of Teleaulax from Eel Pond in Woods Hole and confirmed the identity of these tiny algae using molecular markers.  Dr. Hackett then isolated single cells of Dinophysis and is attempting to feed Teleaulax to Dinophysis.  These experiments are on-going and are approaching a critical point (about 6 weeks from isolation) where we will know if Dinophysis can survive on this prey. 

CICOR sponsored Dr. Hackett’s travel to two international conferences in 2006.  The first was the American Society of Limnology and Oceanography conference in Victoria, BC in June.  Coming from a genomics and evolution background, this conference was an important opportunity for Dr. Hackett to learn about the latest research in the broad field of oceanography and network with the leaders in this field.  Dr. Hackett was chosen to give an oral presentation at the meeting.

The second conference was the International Society for the Study of Harmful Algae conference in Copenhagen, Denmark.  This meeting gave Dr. Hackett the opportunity to see the latest research in the harmful algae community and meet directly with several researchers involved in related work.  Dr. Hackett also learned about two discoveries directly related to his projects, including the discovery of saxitoxin genes in cyanobacteria and attempts to culture Dinophysis using a ciliate prey.  Both of these results will greatly accelerate Dr. Hackett’s current work.  Dr. Hackett was selected to give an oral presentation at this meeting as well.

Dr. Hackett was a Co-PI on a proposal submitted to the National Science Foundation to sequence the genome of a saxitoxin producing cyanobacterium and use bioinformatic methods to discover the related genes in Alexandrium.  A panel will decide on this proposal in October 2006.

In 2006, Dr. Hackett was offered, and has accepted, a faculty position as an assistant professor at the University of Arizona, Department of Ecology and Evolutionary Biology, in Tucson, AZ.  He will begin his new position in January of 2007.

In the last year, Dr. Hackett has had three publications published or accepted, and an additional three submitted:

Hackett, J. D., Yoon, H. S., Bhattacharya, D. Genome Evolution in Dinoflagellates. 2006. In: Genome Evolution in the Algae. Bhattacharya, D. and Katz, L. eds. Oxford University Press.

Yoon, H. S., Hackett, J. D., Bhattacharya, D. In Press. A genomic and phylogenetic perspective on endosymbiosis and algal origin. Journal of Applied Phycology.

Hackett, J. D., Yoon, H. S., Butterfield, N. J., Sanderson, M. J., Bhattacharya, D. Accepted. Plastid endosymbiosis: Sources and timing of the major events. In: Evolution of Aquatic Photoautotrophs, Eds. Falkowski, P., and A. Knoll. Academic Press.

Last updated: May 21, 2009

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