Our group investigates the cellular and molecular interactions underlying mutualistic symbioses between cnidarians, such as corals and anemones, and their photosynthetic dinoflagellate symbionts Symbiodinium spp. These partnerships are of fundamental importance as they form the trophic and structural foundation of coral reef ecosystems. We are interested in the establishment, maintenance and breakdown of these cooperative associations and approach the study of these phenomena at the cellular and molecular level. The Weis group has used a variety of model associations in these examinations and has in recent years focused on the Hawaiian stony coral, Fungia scutaria; a tropical sea anemone, Aiptasia pallida; and a temperate sea anemone, Anthopleura elegantissima.
Weis lab undergraduate Lindsey Ferguson is at the Smithsonian Tropical Research Institute's Naos Island Laboratoires in Panama. Lindsey will spend ten weeks at the field station studying marine invertebrates with Dr. Rachel Collin. Dr. Collin studies evolution of reproduction and mode of development in marine invertebrates, systematics and evolution in marine gastropods, and evolutionary ecology of sex change. Lindsey is working on a project investigating the effects of rainfall on barnacle recruitment in the intertidal zone. This means that I am looking at how many barnacle larvae survive and how large the barnacles are after settling on rocks in areas that remain mostly dry versus areas that experience artificial rainfall. The "rainfall" will be simulated by me holding a sprinkler over some areas.
January 3-8th, 2016 was the annual meeting for the Society of Integrative and Comparative Biology. This year the meeting was held in Portland, Oregon; a short hour and a half drive from Corvallis. We had quite a presence at the meeting this year making six talks and two posters (including current and past Weis lab members). Trevor, a third year graduate student in the lab, made his first talk at an international conference. Needless to say, he gave an outstanding talk about the influence of time of day, nutritional status, and symbiosis status on host cell division rates. The overall takeaway is that host cells show significantly different division patterns under different circadian, nutrient, and symbiosis states. Host symbiotic cells show varied rates of division according to time of day. Starvation increases host cell division rates in aposymbiotic anemones. Starvation may increase rate of algal recolonization and host cell division during onset.
Tivey, T., M. Waianuhea, and V. M. Weis. 2015. Host Cell Division and Symbiont Population Dynamics in the Symbiotic Anemone Aiptasia sp. Integrative and Comparative Biology.
Many non-model species exemplify important biological questions but lack the sequence resources required to study the genes and genomic regions underlying traits of interest. Reef-building corals are famously sensitive to rising seawater temperatures, motivating ongoing research into their stress responses and long-term prospects in a changing climate. A comprehensive understanding of these processes will require extending beyond the sequenced coral genome (Acropora digitifera) to encompass diverse coral species and related anthozoans. Toward that end, we have assembled and annotated reference transcriptomes to develop catalogs of gene sequences for three scleractinian corals (Fungia scutaria, Montastraea cavernosa, Seriatopora hystrix) and a temperate anemone (Anthopleura elegantissima). The catalogs of gene sequences developed in this study made it possible to identify hundreds to thousands of orthologs across diverse scleractinian species and related taxa. We used these sequences for phylogenetic inference, recovering known relationships and demonstrating superior performance over phylogenetic trees constructed using single mitochondrial loci. The resources developed in this study provide gene sequences and genetic markers for several anthozoan species. To enhance the utility of these resources for the research community, we developed searchable databases enabling researchers to rapidly recover sequences for genes of interest. (PDF)
Kitchen, S. A., C. M. Crowder, A. Z. Poole, V. M. Weis, and E. Meyer. 2015. De Novo Assembly and Characterization of Four Anthozoan (Phylum Cnidaria) Transcriptomes. G3: Genes| Genomes| Genetics 5(11), 2441-2452.
Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23C and 28C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization. (PDF)
Crowder, C. M., W. Liang, V. M. Weis, and T. Fan. 2014. Elevated Temperature Alters the Lunar Timing of Planulation in the Brooding Coral Pocillopora damicornis. PLoS ONE 9(10): e107906.
The complement system is an innate immune pathway that in vertebrates, is responsible for initial recognition and ultimately phagocytosis and destruction of microbes. Several complement molecules have been characterized in invertebrates and while most studies have focused on their conserved role in defense against pathogens, little is known about their role in managing beneficial microbes. The purpose of this study was to (1) characterize complement pathway genes in Aiptasia pallida, (2) investigate the evolution of complement genes in invertebrates, and (3) examine the potential dual role of complement genes Factor B (Bf) and MASP in the onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge. The results demonstrate that A. pallida has multiple Factor B genes and one MASP gene. Gene expression analyses revealed a potential role for complement in both onset and maintenance of cnidarian-dinoflagellate symbiosis and immune challenge. The results indicate functional divergence between Ap_Bf-1 and Ap_Bf-2b, and that Ap_Bf-1 and Ap_MASP may be functioning together in an ancestral hybrid of the lectin and alternative complement pathways. Overall, this study provides information on the role of the complement system in a basal metazoan and its role in host-microbe interactions. (PDF)
Poole, A. Z., S. A. Kitchen, and V. M. Weis. 2016. The role of complement in cnidarian-dinoflagellate symbiosis and immune challenge in the sea anemone Aiptasia pallida. Frontiers in Microbiology 7.
Join us in congratulating Dr. Sheila Kitchen who successfully defended her PhD dissertation on Friday afternoon! Sheila gave an excellent public defense presentation about her research on cell signaling processes in cnidarians during symbiont uptake and loss. She also presented work about the potential role of key signaling lipids as cell fate determinants in cnidarian-dinoflagellate symbiosis. Her next adventure will be at Penn State to do a post-doc in the lab of Dr. Illiana Baums. Congratulations Sheila!
Lab Undergraduate to Panama
Weis Lab at SICB 2016
Coral Lunar Brooding
Aiptasia Immune Complement
Congratulations Dr. Sheila Kitchen!!
Giant Green Anemone (Anthopleura xanthogrammica) - University of Washington Friday Harbor Laboratories
Aggregating Sea Anemone (Anthopleura elegantissima) - Beginning the division process in cold tank at OSU
Phagocytosis of symbiont by Fungia larva.
Aiptasia sp. in lab cultures at Oregon State University - All individuals in this finger bowl are clones.
Hematoxylin and eosin stain on Aiptasia sp. mesentery tissue showing gonad development - (left) individual showing
multiple stages of development, including undifferentiated mesentery (m), well-developed oocytes (o), and atretic
oocytes (a). (right) individual contains mostly well-developed oocytes with some atretic oocytes.
Composite Aiptasia sp. tentacle snip under confocal microscope - Stained to determine host cell
cycle stage (red = algae autofluorescence, yellow = S-phase marker [EdU-AF555],
green = mitotic marker [Anti-phospho Histone H3(Ser10)], and purple = nuclear marker [Hoechst].
Christmas sea anemone (Urticina crassicornis) - Grandma's Cove, San Juan Island, Washington
(left) Healthy coral and (right) bleached coral.
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