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Drivers of microbial diversity in the temperate coral Oculina arbuscula
Get PDFDisruption of the coral-algal symbiosis (bleaching) in response to anthropogenic stressors, such as warming and nutrient pollution, represents a significant threat to coral reefs worldwide. Corals are complex meta-organisms (“holobionts”) that host a variety of microbes, and recent evidence supports the role of bacteria in facilitating coral acclimatization to environmental stressors. Oculina arbuscula, an abundant scleractinian coral in the southeastern US, is characterized by a facultative symbiosis with photosynthetic algae (Symbiodiniaceae), allowing for investigation of coral host biology at varying levels of symbiosis. Here, I use 16S and ITS2 metabarcoding to investigate variation in coral-associated bacterial and algal communities in symbiotic (high symbiont density) and aposymbiotic (low symbiont density) O. arbuscula colonies along an inshore-offshore disturbance gradient in North Carolina. I found that O. arbuscula microbiomes significantly differed from the surrounding environment across sites and seasons, and that evenness of O. arbuscula microbiomes was higher in nearshore environments. Two bacterial taxa (Thiovulum and Burkholderiaceae) that have previously been suggested as disease indicators in tropical corals were present in high relative abundance across O. arbuscula samples, suggesting potential functional roles for these bacteria within the temperate coral holobiont. Lastly, coral-associated bacterial diversity and community structure did not differ between symbiotic states, but symbiont density was found to be a strong predictor of alpha diversity. Interestingly, the relationship between density and alpha diversity varied between sites, which I explain using a model incorporating ideas from resource allocation theory and the mutualism-parasitism hypothesis. Overall, this study provides a novel investigation of the microbial ecology of O. arbuscula, furthering our understanding of the coral-algal symbiosis and providing foundational knowledge of an ecologically important species to North Carolina hardbottom ecosystems.Master of Scienc
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Marine invertebrate-microbial bioactive metabolite symbioses
Get PDFConspicuous and soft-bodied planktonic marine invertebrate larvae often use bioactive compounds for defense against predators. Bioactive compounds play a significant role in shaping the host ecology, and in some cases, the molecules are synthesized by microbial symbionts. This dissertation addresses fundamental questions of bioactive metabolite symbioses between metazoans and microbes. The bryozoan Bugula neritina transmits the symbiotic proteobacterium 'Candidatus Endobugula sertula,' via its larvae. E. sertula synthesizes the bryostatins, which protect B. neritina larvae from predation in the environment. Development of a method for simultaneous in situ bryostatin and E. sertula localization demonstrates that embryos are coated with bryostatins before release from adult colonies, and there is an ontogenetic shift in bryostatin concentration and localization throughout the host life cycle. E. sertula is present in all host life stages of the host, suggesting that bryostatin biosynthesis may somehow be regulated, reserved for specific events in the life history, such as the protection of larvae. The second invertebrate studied in this dissertation is the sponge Corticium candelabrum. C. candelabrum possesses tedanolides, anti-tumor polyketides that might possibly be produced by bacteria in the sponge. Two chapters in this dissertation are dedicated to microbial assemblages associated with developing C. candelabrum embryos. Both Archaea and Bacteria are present throughout C. candelabrum embryonic development. Here we identify three specific bacterial taxa, and show that there are likely dozens more, that are vertically transmitted in C. candelabrum and consistently associated with it across space and time. One of these species, a strain of alpha-proteobacterium a-CC01, is present throughout embryogenesis and is also present in swimming larvae. These studies show that C. candelabrum inoculates vertically transmits a specific, diverse microbial community. A main theme linking the studies in this dissertation is vertical transmission of microbes in marine invertebrates. Embryo and larva isolation allows identification of specific microbial associates in marine invertebrates by decreasing the complexity of microbes in a sample. In addition, understanding of microbial assemblages in marine invertebrate embryos and larvae offers valuable insight into how species-specific invertebrate-microbe associations are maintained in the environmen
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Localization of ‘Candidatus Endobugula sertula’ and the bryostatins throughout the life cycle of the bryozoan Bugula neritina
No full text‘Candidatus Endobugula sertula,’ the uncultivated γ-proteobacterial symbiont of the marine bryozoan Bugula neritina, synthesizes bryostatins, complex polyketides that render B. neritina larvae unpalatable to predators. Although the symbiosis is well described, little is known about the locations of ‘E. sertula’ or the bryostatins throughout larval settlement, metamorphosis and early development. In this study, we simultaneously localized ‘E. sertula’ and the bryostatins in multiple stages of the B. neritina life cycle, using a novel bryostatin detection method based on its known ability to bind mammalian protein kinase C. Our results suggest that the bryostatins are deposited onto the exterior of B. neritina larvae during embryonic development, persist on the larval surface throughout metamorphosis and are shed prior to cuticle formation. During metamorphosis, ‘E. sertula’ remains adhered to the larval pallial epithelium and is incorporated into the preancestrula cystid tissue layer, which ultimately develops into a bud and gives rise to the next zooid in the colony. Colocalization of bryostatin signal with aggregates of ‘E. sertula’ in buds of ancestrulae suggested new synthesis of bryostatins in ancestrulae. In adult B. neritina colonies, symbiont microcolonies were observed in the funicular cords of rhizoids, which likely result in asexual transmission of ‘E. sertula’ to regenerated colonies. Furthermore, bryostatin signal was detected on the surface of the rhizoids of adult B. neritina colonies. Through simultaneous localization of the bryostatins and the ‘E. sertula,’ we determined how ‘E. sertula’ is transmitted, and identified shifts in bryostatin localization throughout the life cycle of the host B. neritina
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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