研究领域
Aquatic viruses recently became a focus of interest when abundances of viruses in natural waters were documented to be in excess of 10,000,000 /mL (Bergh et al. 1989). Through infection of aquatic organisms, these viruses impact the community composition and diversity of aquatic ecosystems (Bratbak et al. 1996), nutrient cycling (Wilhelm & Suttle 1999) and may act as vectors for genetic transfer (Suttle et al. 1990). Since phytoplankton form the ‘base’ of aquatic food webs, natural succession, species shifts, and changes in phytoplankton population dynamics resulting from viral infections have the potential to influence community structure and have cascading effects in aquatic ecosystems (ie. Larsen et al. 2001). Indeed, the most drastic impacts of viruses on algal populations are evident during algal blooms when high host densities result in the rapid propagation of infection throughout a population (Suttle et al. 1990, Bratbak et al. 1993, Nagasaki et al. 1994, Suttle 2000). We are beginning appreciate that these ultramicroscopic entities are responsible for bottom-up control of the aquatic food webs; food webs that we rely on heavily, and, paradoxically, understand little about.
Given the vastness of aquatic microbial ecology and the unending supply of fascinating ideas to study, I am developing a research program to specifically address one general topic: the role of viruses in the ecology of microalgae. I am particularly interested in pursuing the following:
a) Isolating and characterizing novel algal viruses – Viruses have recently been found to infect members of every major algal group, however, only representatives from each group have been investigated. There are likely viruses infecting every species of algae. Given the number of diverse viruses known to infect individual species, there may even be a number of different viruses that infect each algal species. One of the first steps toward understanding the importance of algal viruses and their role in the ecology of algal populations is to know which algae can be infected by what viruses. The identification of viruses that infect commercially important species is of particular interest. This can only be achieved by isolating and characterizing new algal viruses.
b) Developing molecular tools for identifying and enumerating algal viruses, especially in lieu of tools for monitoring invasive species (algal hosts), biodiversity, and the health of the aquatic environment – Since viruses are obligate pathogens their presence indicates the existence of their host. This presents a powerful tool for detecting invasive algal species, monitoring algal biodiversity, and assessing the overall health of aquatic environments. Through the development of molecular tools we will be able to rapidly identify the presence and abundance of algal viruses in the natural environment. The molecular data generated through developing these tools will also be useful for examining the evolutionary and phylogenetic relationships between novel and known viruses, leading to a greater understanding of microbial diversity.
c) Determining the role of viruses in controlling the maintenance, population and community dynamics, and dissemination of harmful algal blooms – Certain algal viruses have been associated with the termination of algal blooms. As novel viruses are discovered, elucidating their role in the ecology of their bloom-forming hosts will further our understanding of bloom dynamics, and enable us to develop better prediction and management strategies for the natural resources impacted by harmful algal blooms.
d) Examining the factors that determine the susceptibility of algal hosts to viral infections – Successful infection begins with the interaction of a virus with receptors on the host cell-surface known as viral receptors. These receptors have other functions to the host and are naturally present on the surface of host cells. Viruses have evolved to exploit these receptors to gain entry into cells, and therefore the receptor will, in part, determine the susceptibility of different hosts to the same virus. As viral attachment and entry into the host are the first steps in successful infection, it makes sense to begin understanding the regulation of infection here.
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J.E. Lawrence. Viral Contamination of Algal cultures. In: Algal Culturing Techniques (Ed. R.A. Andersen) Academic Press. In press.
J.E. Lawrence & C.A. Suttle. The effect of viral infection on sinking rates in Heterosigma akashiwo and its implications for bloom dynamics. Aquatic Microbial Ecology. In press.
P. Juneau, J.E. Lawrence, C.A. Suttle & P.J. Harrison. 2003. Detection of viral infection in phytoplankton using pulse-amplitude modulated fluorometry. Aquatic Microbial Ecology 31:9-7.
V. Tai, J.E. Lawrence, A. Lang, A.M. Chan, A. Culley & C.A. Suttle. 2003. Characterization of HaRNAV, a novel single-stranded RNA virus causing lysis of the toxic bloom-forming alga, Heterosigma akashiwo (Raphidophyceae). Journal of Phycology 39:343-352.
J.E. Lawrence, A.M. Chan & C.A. Suttle. 2002. Viruses causing lysis of the toxic bloom-forming alga, Heterosigma akashiwo (Raphidophyceae) in coastal sediments of British Columbia, Canada. Limnology and Oceanography 47(2):545-550.
A.C. Ortmann, J.E. Lawrence & C.A. Suttle. 2002. Lytic viral production and lysogeny in heterotrophic bacterial and cynaobacterial communities. Microbial Ecology 43(2):225-231.
J.E. Lawrence, A.M. Chan & C.A. Suttle. 2001. A novel virus causes lysis of the toxic bloom-forming alga, Heterosigma akashiwo. Journal of Phycology 37(2):1-7.
J.E. Lawrence, J. Grant, M.A. Quilliam, A.G. Bauder & A.D. Cembella. 2000. Colonization and growth of the toxic dinoflagellate Prorocentrum lima and associated fouling macroalgae on mussels in suspended culture. Marine Ecology Progress Series 201:147-154.
J.E. Lawrence, A.G. Bauder, M.A. Quilliam & A.D. Cembella. 1998. Prorocentrum lima: A putative link to diarrhetic shellfish poisoning in Nova Scotia, Canada. In: Harmful Microalgae (Ed. B. Reguera, J. Blanco, M.L. Fernandez & T. Wyatt) Xunta de Galicia and UNESCO. pp. 78-79.
J.E. Lawrence & A.D. Cembella. 1998. An immunolabelling technique for the detection of diarrhetic shellfish toxins in individual dinoflagellate cells. Phycologia 38(1): 60-65.
J.E. Lawrence, A.D. Cembella, N.W. Ross, & J.L.C. Wright. 1998. Cross-reactivity of an anti-okadaic acid antibody to dinophysistoxin-4 (DTX-4), dinophysistoxin-5 (DTX-5), and an okadaic acid diol ester. Toxicon 36(8): 1193-1196.
J.E. Lawrence, C.P.D. Brussaard, C.A. Suttle. 2004. Flow-cytometric analysis of Heterosigma akashiwo permits rapid detection of viral infections. Ocean Research Conference, American Society of Limnology and Oceanography / The Oceanography Society, Honolulu, HI, USA.
J.E. Lawrence, C.M. Frederickson, S.M. Short & C.A. Suttle. 2002. Interrogating marine sediments to examine historical virioplankton diversity. Aquatic Sciences Meeting, American Society of Limnology and Oceanography, Victoria, BC.
J.E. Lawrence & C.A. Suttle. 2002. The effect of viral infection on sinking rates in Heterosigma akashiwo and its implications for bloom dynamics. 3rd International Algal Virus Workshop, Hiroshima, Japan.
J.E. Lawrence & C.A. Suttle. 2002. Invited. Novel algal viruses and their role in the bloom dynamics of Heterosigma akashiwo. Ocean Science Meeting, American Geophysical Union / American Society of Limnology and Oceanography, Honolulu, HI, USA. Eos. Trans. AGU, 80(49): OS12T-05.
C.A. Suttle, V. Tai, S.M. Short & J.E. Lawrence. 2002. Keynote Lecture. Algal virus diversity and its implications for understanding viru-host interactions in nature. 3rd International Algal Virus Workshop, Hiroshima, Japan
P. Juneau, J.E. Lawrence, C.A. Suttle & P.J. Harrison. 2001. Use of PAM-fluorometry to detect viral infection of phytoplankton. Aquatic Sciences Meeting, American Society of Limnology and Oceanography, Albuquerque, NM, USA. Abstracts p.76.
J.E. Lawrence & C.A. Suttle. 2001. Viruses causing mortality of Heterosigma akashiwo in coastal sediments of British Columbia. In: Proceedings of the Sixth Canadian Workshop of Harmful Marine Algae (Ed. J.N.C. Whyte) Can. Tech. Rep. Fish. Aquat. Sci. 2386: 52.
A.C. Ortmann, J.E. Lawrence & C.A. Suttle. 2001. Viral Production and the induction of lysogens in coastal seawater. Aquatic Sciences Meeting, American Society of Limnology and Oceanography, Albuquerque, NM, USA. Abstracts p.106.
N.G. Taylor, J.E. Lawrence & C.A. Suttle. 2001. Seasonal variation in the abundance of viruses infecting Heterisigma akashiwo on the B.C. coast. In: Proceedings of the Sixth Canadian Workshop of Harmful Marine Algae (Ed. J.N.C. Whyte) Can. Tech. Rep. Fish. Aquat. Sci. 2386: 113.
J.E. Lawrence, A.M. Chan & C.A. Suttle. 2000. A previously unknown virus with novel characteristics causes lysis of the toxic bloom forming alga, Heterosigma akashiwo. 2000 Ocean Science Meeting, American Geophysical Union / American Society of Limnology and Oceanography, San Antonio, TX, USA. Eos. Trans. AGU, 80(49): OS11J-07
C.A. Suttle, A.M. Chan & J.E. Lawrence. 2000. Strong evidence for wide distribution and high abundance of viruses infecting the toxic bloom forming alga Heterosigma akashiwo in coastal sediments of British Columbia. 2000 Ocean Science Meeting, American Geophysical Union / American Society of Limnology and Oceanography, San Antonio, TX, USA. Eos. Trans. AGU, 80(49): OS11J-06
V. Tai, J.E. Lawrence, A.M. Chan & C.A. Suttle. 2000. Isolation and characterization of viruses infecting Heterosigma akashiwo (Raphidophyceae). Northwest Algal Symposium, Vancouver, BC, Canada.
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