My research focuses on symbiotic interactions between host and symbiont including how the symbiosis is established (onset), maintained, and how small genetic changes can prevent the symbiosis from occurring leading to host specificity. As such I combine ecological and evolutionary questions with molecular techniques. To address these questions, I have chosen to work with corals as they host many different organisms including mutualists and parasites.
Apicomplexans in corals
Apicomplexans are protists that comprise almost entirely of parasites including the causal agents of human malaria. It turns out corals host a group of apicomplexans as well and a single species, Gemmocystis cylindrus, was described by Esther Peters and Steve Upton in 1986. Since then my research has helped uncover lots of diversity among these putative coral parasites with evidence of host specificity. I was able molecularly screen historic coral samples going back 15 years and found that apicomplexans are consistently found associated with coral tissue. http://www.defendersblog.org/2013/05/another-potential-threat-to-corals/
Excitingly, these symbionts appear to be evolutionary related to a group of apicomplexans called the coccidians. The coccidians include the opportunistic human parasites Toxoplasma gondii and Cyclospora cayetanensis as well as numerous other parasites of livestock and fowl. They also are transmitted vertically from parental colonies in several species of brooding corals (brooding corals have internal fertilization and release larvae). This allows us to utilize brooded larvae as a source for acquiring and describing these coral-associated apicomplexans. If we look at a variable region of the genome - the internal transcribed spacer (ITS) region of the ribosomal operon - it appears there is quite a bit of difference between apicomplexans associated with different coral hosts. Therefore, we are likely vastly underestimating the diversity given there is only one described species.
It is also tempting to hypothesize about the nature of the interaction between corals and apicomplexans. Almost all (except one weird example) are parasitic symbionts. Given this and their high prevalence, it would imply that corals all harbor an opportunistic parasite! Trying to define this interaction and determining potential cost is a direction I would like to pursue in the future.
Dinoflagellates in cnidarians
Interestingly, dinoflagellates are the sister lineage of apicomplexans! Unlike apicomplexans, these dinoflagellates provide corals with photosynthetically-fixed carbon in exchange for a comfy place to live. These dinoflagellates are part of a remarkably diverse genus named Symbiodinium, which is divided into 9 different monophyletic clades (A-I). My research focuses on the fine scale diversity among just a single clade, clade B (specifically B1s). This clade associates with numerous Caribbean species of hard and soft corals. However, if you look close enough they seem to segregate by host species implying high specificity! My research, with the help of undergraduates at Oregon State University (See next page), explores the interaction between a host anemone and very closely related Symbiodinium during early infection.
Stress tolerance in cnidarians
As part of my postdoctoral work, I am also examining transcriptional changes associated with stress challenges in coral larvae and the local Oregon sea anemone, Anthopleura elegantissima. In brief, I am using RNAseq to examine genes that are significantly up- and down-regulated in response to a stress (generally heat or salt). Understanding how organisms react to changes in conditions in the laboratory can provide insights into how they might handle heating as predicted by global climate change.
Apicomplexans in corals
Apicomplexans are protists that comprise almost entirely of parasites including the causal agents of human malaria. It turns out corals host a group of apicomplexans as well and a single species, Gemmocystis cylindrus, was described by Esther Peters and Steve Upton in 1986. Since then my research has helped uncover lots of diversity among these putative coral parasites with evidence of host specificity. I was able molecularly screen historic coral samples going back 15 years and found that apicomplexans are consistently found associated with coral tissue. http://www.defendersblog.org/2013/05/another-potential-threat-to-corals/
Excitingly, these symbionts appear to be evolutionary related to a group of apicomplexans called the coccidians. The coccidians include the opportunistic human parasites Toxoplasma gondii and Cyclospora cayetanensis as well as numerous other parasites of livestock and fowl. They also are transmitted vertically from parental colonies in several species of brooding corals (brooding corals have internal fertilization and release larvae). This allows us to utilize brooded larvae as a source for acquiring and describing these coral-associated apicomplexans. If we look at a variable region of the genome - the internal transcribed spacer (ITS) region of the ribosomal operon - it appears there is quite a bit of difference between apicomplexans associated with different coral hosts. Therefore, we are likely vastly underestimating the diversity given there is only one described species.
It is also tempting to hypothesize about the nature of the interaction between corals and apicomplexans. Almost all (except one weird example) are parasitic symbionts. Given this and their high prevalence, it would imply that corals all harbor an opportunistic parasite! Trying to define this interaction and determining potential cost is a direction I would like to pursue in the future.
Dinoflagellates in cnidarians
Interestingly, dinoflagellates are the sister lineage of apicomplexans! Unlike apicomplexans, these dinoflagellates provide corals with photosynthetically-fixed carbon in exchange for a comfy place to live. These dinoflagellates are part of a remarkably diverse genus named Symbiodinium, which is divided into 9 different monophyletic clades (A-I). My research focuses on the fine scale diversity among just a single clade, clade B (specifically B1s). This clade associates with numerous Caribbean species of hard and soft corals. However, if you look close enough they seem to segregate by host species implying high specificity! My research, with the help of undergraduates at Oregon State University (See next page), explores the interaction between a host anemone and very closely related Symbiodinium during early infection.
Stress tolerance in cnidarians
As part of my postdoctoral work, I am also examining transcriptional changes associated with stress challenges in coral larvae and the local Oregon sea anemone, Anthopleura elegantissima. In brief, I am using RNAseq to examine genes that are significantly up- and down-regulated in response to a stress (generally heat or salt). Understanding how organisms react to changes in conditions in the laboratory can provide insights into how they might handle heating as predicted by global climate change.
