Cellular uptake and biological activity of synthetic hammerhead ribozymes

Glioblastoma Multiforme (GBM) is a highly malignant form of brain cancer for which there is no effective cure. The over-expression of a number of genes, including the epidermal growth factor receptor (EGFr), has been implicated as a causative factor of tumourigenesis. Ribozymes are a class of ribonucleic acid that possess enzymatic properties. They can inhibit gene-expression in a highly sequence specific manner by catalysing the trans-cleavage of target RNA. The potential use of synthetic hammerhead ribozymes as novel anti-brain tumour agents was investigated in this study. The successful use of synthetic, exogenously administered ribozymes for such applications will require chemical modifications that improve biological stability and a fundamental understanding of cellular uptake mechanisms. Chimeric 2'-O-methylated hammerhead ribozymes proved to be significantly more stable (>4000-fold) in serum than unmodified RNA ribozymes and exhibited high in vitro catalytic activity. The cellular association of an internally [32P]-labelled 2'-O-methylated chimeric ribozyme in U87-MG human glioma cells was temperature-, energy- and pH-dependent and involved an active process that could be competed with a variety of polyanions. Indications are that the predominant mechanism of uptake is by adsorptive and / or receptor mediated endocytosis. Twenty 2'-O-methylated chimeric ribozymes were designed to cleave various sites along the EGFr mRNA. In vitro, 18 ribozymes exhibited high activity in cleaving a complementary short substrate. Using LipofectAMINETM as a delivery agent, the efficacy of these ribozymes was evaluated in the A431 cell line, which expresses amplified levels of EGFr. Studies revealed that although the ribozymes were taken up by the cells and remained stable over a period of 4 days, no significant reduction in either EGFr expression or cell proliferation was evident. The presence of telomerase, a ribonucleoprotein responsible for telomere elongation, has been strongly associated with tumour progression. The biological activity of a 2'-O-methylated ribozyme targeted against the RNA component of telomerase was determined. The ribozyme exhibited specific dose-dependent inhibition of telomerase activity in U87-MG cell lysates with an IC50 of –4μM. When 4μM ribozyme was delivered to intact U87-MG cells, complexed to LipofectAMINETM, telomerase activity was significantly reduced to 74.5±4.17% of the untreated control. Free ribozyme showed no significant inhibitory effect demonstrating the importance of an appropriate delivery system for optimum delivery of exogenously administered ribozymes.

A combinatorial approach to the chemical synthesis and biological evaluation of 3,4,5-trisubstiituted furan-2(5H)-ones

Many important natural products contain the furan-2(5H)-one structure. The structure of this molecule lends itself to manipulation using combinatorial techniques due to the presence of more than one site for the attachment of different suhstituents. By developing different reaction schemes at the three sites available for attachment on the furan-2(5H)-one scaffold, combinatorial chemistry techniques can be employed to assemble libraries of novel furan 2(5H)-ones. These libraries can then be entered into various biological screening programmes. This approach will enable a vast diversity or compounds to be examined, in the hope or finding new biologically active Iead structures. The work in this thesis has investigated the potential that combinatorial chemistry has in the quest for new biologically active lead structures based on the furan-2(5H)-one structure. Different reactions were investigated with respect to their suitability for inclusion in a library. Once sets of reactions at the various sites had been established, the viability of these reactions in the assembly of combinatorial libraries was investigated. Purification methods were developed, and the purified products entered into suitable biological screening tests. Results from some of these tests were optimised using structure activity relationships, and the resulting products re-screened. The screening tests performed were for anticancer and antimicrobial activity, cholecystokinin (CCK-B) antagonism and anti-inflammatory activity (in the quest for novel cyclo-oxygenase (COX-2) selective non-steroidal anti-inflammatory drugs). It has been shown that many reactions undergone by the furan-2(5H)-one structure are suitable for the assembly of a combinatorial library. Investigation into the assembly of different libraries has been carried out with initial screening results included. From this work, further investigation into combinatorial library assembly and structure activity relationships of screened reaction products can be undertaken.

Biological barriers to the nasal delivery of peptide drugs

The nasal absorption of larger peptide and protein drugs is generally low. The importance of the mucus layer and enzymic degradation in reducing absorption were investigated. Reversed-phase high-performance liquid chromatographic (HPLC) methods were developed to assay a variety of compounds. Pig gastric mucus (PGM) was selected to investigate the importance of the mucus layer. A method of treating and storing PGM was developed and evaluated which was representative of the gel in vivo. The nature of the mucus barrier was evaluated in vitro with three-compartment diffusion cells and a series of compounds with differing physicochemical properties. Mucus retarded the diffusion of all the compounds with molecular weight and charge exerting a marked effect. Binding to mucus was investigated by a centrifugation method. All of the compounds tested were found to bind to mucus with the exception of the negatively charged molecule benzoic acid. The small peptides did not demonstrate greater binding to mucus than any of the other compounds evaluated. The effect of some absorption enhancers upon the rate of diffusion of tryptophan through mucus was determined in vi tro. At the concentrations employed the enhancers EDTA, N-acetylcysteine and taurodeoxycholic acid exerted no effect, whilst taurocholic acid and cholic acid, were found to slightly reduce the rate of diffusion. The intracellular and luminal proteolytic activity of the nose was investigated in the sheep animal model with a nasal mucosal homogenate and a nasal wash preparation respectively and a series of chemically similar peptides. Hydrolysis was also investigated with the proteolytic enzymes carboxypeptidase A, cytosolic leucine aminopeptidase and microsomal leucine aminopeptidase. Sheep nasal mucosa possesses significant peptide hydrolase activity capable of degrading all the substrates tested. Considerable variation in susceptibility was observed. Degradation occurred excl us i ve ly at the pept ide bond between the aromatic amino ac id and glycine, indicating some specificity for aromatic amino acids. Hydrolysis profiles indicated the presence of both aminopeptidase and carboxypeptidase enzymes. The specific activity of the microsomal fraction was found to be greater than the cytosolic fraction. Hydrolysis in the nasal wash indicated the presence of either luminal or loosely-bound proteases, which can degrade peptide substrates. The same specificity for aromatic amino acids was observed and aminopeptidase activity demonstrated. The specific activity of the nasal wash was smaller than that of the homogenate.

Characterisation of electrospun polystyrene scaffolds for three-dimensional in vitro biological studies

The purpose of this study was to produce a well-characterised electrospun polystyrene scaffold which could be used routinely for three-dimensional (3D) cell culture experimentation. A linear relationship (p<0.01p<0.01) between three principal process variables (applied voltage, working distance and polymer concentration) and fibre diameter was reliably established enabling a mathematical model to be developed to standardise the electrospinning process. Surface chemistry and bulk architecture were manipulated to increase wetting and handling characteristics, respectively. X-ray photoelectron spectroscopy (XPS) confirmed the presence of oxygen-containing groups after argon plasma treatment, resulting in a similar surface chemistry to treated tissue culture plastic. The bulk architecture of the scaffolds was characterised by scanning electron microscopy (SEM) to assess the alignment of both random and aligned electrospun fibres, which were calculated to be 0.15 and 0.66, respectively. This compared to 0.51 for collagen fibres associated with native tissue. Tensile strength and strain of approximately of 0.15 MPa and 2.5%, respectively, allowed the scaffolds to be routinely handled for tissue culture purposes. The efficiency of attachment of smooth muscle cells to electrospun scaffolds was assessed using a modified 3-[4,5-dimethyl(thiazol-2yl)-3,5-diphery] tetrazolium bromide assay and cell morphology was assessed by phalloidin-FITC staining of F-actin. Argon plasma treatment of electrospun polystyrene scaffold resulted in significantly increased cell attachment (p<0.05p<0.05). The alignment factors of the actin filaments were 0.19 and 0.74 for the random and aligned scaffold respectively, compared to 0.51 for the native tissue. The data suggests that electrospinning of polystyrene generates 3D scaffolds which complement polystyrene used in 2D cell culture systems.

Learning from mother nature:exploiting a biological antioxidant for the melt stabilisation of polymers

An overview of the antioxidant role of the biologically active form of vitamin E, α-tocopherol, in polyolefins is discussed. The effect of the vitamin antioxidant on the melt and colour stability of polyethylene (PE) and polypropylene (PP) is highlighted. It is shown that tocopherol is a highly effective antioxidant that results in superior melt stabilisation of polyolefins particularly when used at much lower concentration than that needed for conventional synthetic hindered phenol processing stabilisers. As with other hindered phenols,α-tocopherol imparts also some colour to the polymer but this is shown to be reduced drastically in the presence of other antioxidants, such as phosphites, or other additives, such as polyhydric alcohols.

The Problems of Forming the Inner Personal Conflict as a Factor which Influences Decision-making

the article views examine the problems concerning with the sources of origin of unconscious the inner personal conflicts and the way the presence of this factor is reflected on the decision-making process by a person.

Environmental lead contamination in Miami inner-city area

The purpose of the study was to evaluate the magnitude of environmental lead contamination in the downtown area of Miami. Lead inspections took place at 121 homes in Little Haiti and Liberty City and involved the collection ofrepresentative samples from floors, window wells, tap water, soil and air. Community health workers (CHWs) trained in interview and safety techniques went from door to door to enlist participation. On-site investigations were tailored to areas most utilized by children underthe age of6 years. The presence of lead-containing paint was also investigated in situ via X-ray fluorescence (XRF) analysis. Results: Of the sampling areas, the window wells area had the most abundant occurrence of lead. On analysis, 24% of sites returned window well samples with lead levels above Department of Housing and Urban Development (HUD) guidelines. Of the soil samples, the playgrounds around the house had the highest concentration of lead. Soil sampling demonstrated that 27.5% of sites returned samples with lead levels (400 to 1600 ppm) inexcess of HUD/Environmental Protection Agency (EPA) standards. Positive XRF readings in one or more components were returned by 18% of sites. Conclusions: More than half of the houses in these two neighborhoods exhibited unacceptably high levels of lead dust and soil in areas where children live and play. Limitations of this study did not allow the assessment of how many children in this area are affected. A more comprehensive study including other areas of Miami-Dade County with older housing stock is recommended.

Determination of signature volatile odor chemicals emanating from novel biological specimens by non-invasive analytical techniques for the potential use in forensic identifications

Human scent, or the volatile organic compounds (VOCs) produced by an individual, has been recognized as a biometric measurement because of the distinct variations in both the presence and abundance of these VOCs between individuals. In forensic science, human scent has been used as a form of associative evidence by linking a suspect to a scene/object through the use of human scent discriminating canines. The scent most often collected and used with these specially trained canines is from the hands because a majority of the evidence collected is likely to have been handled by the suspect. However, the scents from other biological specimens, especially those that are likely to be present at scenes of violent crimes, have yet to be explored. Hair, fingernails and saliva are examples of these types of specimens. ^ In this work, a headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technique was used for the identification of VOCs from hand odor, hair, fingernails and saliva. Sixty individuals were sampled and the profiles of the extracted VOCs were evaluated to assess whether they could be used for distinguishing individuals. Preliminary analysis of the biological specimens collected from an individual (intra-subject) showed that, though these materials have some VOCs in common, their overall chemical profile is different for each specimen type. Pair-wise comparisons, using Spearman Rank correlations, were made between the chemical profiles obtained from each subject, per a specimen type. Greater than 98.8% of the collected samples were distinguished from the subjects for all of the specimen types, demonstrating that these specimens can be used for distinguishing individuals. ^ Additionally, field trials were performed to determine the utility of these specimens as scent sources for human scent discriminating canines. Three trials were conducted to evaluate hair, fingernails and saliva in comparison to hand odor, which was considered the standard source of human odor. It was revealed that canines perform similarly to these alternative human scent sources as they do to hand odor implying that, though there are differences in the chemical profiles released by these specimens, they can still be used for the discrimination of individuals by trained canines.^

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Data to Decision in a Dynamic Ocean: Robust Species Distribution Models and Spatial Decision Frameworks

Human use of the oceans is increasingly in conflict with conservation of endangered species. Methods for managing the spatial and temporal placement of industries such as military, fishing, transportation and offshore energy, have historically been post hoc; i.e. the time and place of human activity is often already determined before assessment of environmental impacts. In this dissertation, I build robust species distribution models in two case study areas, US Atlantic (Best et al. 2012) and British Columbia (Best et al. 2015), predicting presence and abundance respectively, from scientific surveys. These models are then applied to novel decision frameworks for preemptively suggesting optimal placement of human activities in space and time to minimize ecological impacts: siting for offshore wind energy development, and routing ships to minimize risk of striking whales. Both decision frameworks relate the tradeoff between conservation risk and industry profit with synchronized variable and map views as online spatial decision support systems.

For siting offshore wind energy development (OWED) in the U.S. Atlantic (chapter 4), bird density maps are combined across species with weights of OWED sensitivity to collision and displacement and 10 km2 sites are compared against OWED profitability based on average annual wind speed at 90m hub heights and distance to transmission grid. A spatial decision support system enables toggling between the map and tradeoff plot views by site. A selected site can be inspected for sensitivity to a cetaceans throughout the year, so as to capture months of the year which minimize episodic impacts of pre-operational activities such as seismic airgun surveying and pile driving.

Routing ships to avoid whale strikes (chapter 5) can be similarly viewed as a tradeoff, but is a different problem spatially. A cumulative cost surface is generated from density surface maps and conservation status of cetaceans, before applying as a resistance surface to calculate least-cost routes between start and end locations, i.e. ports and entrance locations to study areas. Varying a multiplier to the cost surface enables calculation of multiple routes with different costs to conservation of cetaceans versus cost to transportation industry, measured as distance. Similar to the siting chapter, a spatial decisions support system enables toggling between the map and tradeoff plot view of proposed routes. The user can also input arbitrary start and end locations to calculate the tradeoff on the fly.

Essential to the input of these decision frameworks are distributions of the species. The two preceding chapters comprise species distribution models from two case study areas, U.S. Atlantic (chapter 2) and British Columbia (chapter 3), predicting presence and density, respectively. Although density is preferred to estimate potential biological removal, per Marine Mammal Protection Act requirements in the U.S., all the necessary parameters, especially distance and angle of observation, are less readily available across publicly mined datasets.

In the case of predicting cetacean presence in the U.S. Atlantic (chapter 2), I extracted datasets from the online OBIS-SEAMAP geo-database, and integrated scientific surveys conducted by ship (n=36) and aircraft (n=16), weighting a Generalized Additive Model by minutes surveyed within space-time grid cells to harmonize effort between the two survey platforms. For each of 16 cetacean species guilds, I predicted the probability of occurrence from static environmental variables (water depth, distance to shore, distance to continental shelf break) and time-varying conditions (monthly sea-surface temperature). To generate maps of presence vs. absence, Receiver Operator Characteristic (ROC) curves were used to define the optimal threshold that minimizes false positive and false negative error rates. I integrated model outputs, including tables (species in guilds, input surveys) and plots (fit of environmental variables, ROC curve), into an online spatial decision support system, allowing for easy navigation of models by taxon, region, season, and data provider.

For predicting cetacean density within the inner waters of British Columbia (chapter 3), I calculated density from systematic, line-transect marine mammal surveys over multiple years and seasons (summer 2004, 2005, 2008, and spring/autumn 2007) conducted by Raincoast Conservation Foundation. Abundance estimates were calculated using two different methods: Conventional Distance Sampling (CDS) and Density Surface Modelling (DSM). CDS generates a single density estimate for each stratum, whereas DSM explicitly models spatial variation and offers potential for greater precision by incorporating environmental predictors. Although DSM yields a more relevant product for the purposes of marine spatial planning, CDS has proven to be useful in cases where there are fewer observations available for seasonal and inter-annual comparison, particularly for the scarcely observed elephant seal. Abundance estimates are provided on a stratum-specific basis. Steller sea lions and harbour seals are further differentiated by ‘hauled out’ and ‘in water’. This analysis updates previous estimates (Williams & Thomas 2007) by including additional years of effort, providing greater spatial precision with the DSM method over CDS, novel reporting for spring and autumn seasons (rather than summer alone), and providing new abundance estimates for Steller sea lion and northern elephant seal. In addition to providing a baseline of marine mammal abundance and distribution, against which future changes can be compared, this information offers the opportunity to assess the risks posed to marine mammals by existing and emerging threats, such as fisheries bycatch, ship strikes, and increased oil spill and ocean noise issues associated with increases of container ship and oil tanker traffic in British Columbia’s continental shelf waters.

Starting with marine animal observations at specific coordinates and times, I combine these data with environmental data, often satellite derived, to produce seascape predictions generalizable in space and time. These habitat-based models enable prediction of encounter rates and, in the case of density surface models, abundance that can then be applied to management scenarios. Specific human activities, OWED and shipping, are then compared within a tradeoff decision support framework, enabling interchangeable map and tradeoff plot views. These products make complex processes transparent for gaming conservation, industry and stakeholders towards optimal marine spatial management, fundamental to the tenets of marine spatial planning, ecosystem-based management and dynamic ocean management.

Spic'ing into Existence: Epitaph, Epithet, and the Ethnopoetic Imagination

Quién Es, Quién Somos? Spic’ing into Existence claims a four-fold close-reading: first, analysis of texts: from theoretical meditations to (prison) memoir and film. Second, a half dozen central figures appear, largely Latinx and black American. They cut across a score of registers, socio-economics, ideological reservations, but all are, as Carl Carlton sang, poetry in motion. Writers, poets, theologians, pathologists, artists, comedians, actors, students whose vocation is invocation, the inner surge of their calling. Third, the manuscript draws from a series of historical moments—from radical liberation of the late 60s, to contemporary student activism. Finally, this body of work is movement, in all its social, gestural, and kinesthetic viscera. From this last heading, we peel away layers of what I call the ethnopoet, the fascia undoing that reveals its bio-political anatomy, dressing its bare life with kinship speech. First, the social revolutions of the Civil Rights, Black Power, abolitionism, the Black Panthers and Young Lords, boycotts and jarring artistic performances. These events are superficial not in vain sense, but key epicenters of underground murmurings, the workings of a cunning assailant. She robs not lavish estates, but another day to breathe. Gesturally, as perhaps the interlocutor, lies this author, interspersing his own diatribes to conjure her presence. The final branch is admittedly the most intangible. Kinesthetically, we map the nimbleness, footwork lígera of what I call the ethnopoet. Ethnopoet is no mere aggregate of ethnicity and poetry, but like chemical reaction, the descriptor for its behavior under certain pressures, temperatures, and elements. Elusive and resisting confinement, and therefore definition, the ethnopoet is a shapeshifting figure of how racialized bodies [people of color] respond to hegemonic powers. She is, at bottom, however, a native translator, the plural-lensed subject whose loyalty is only to the imagination of a different world, one whose survival is not contingent upon her exploitation. The native translator’s constant re-calibrations of oppressive power apparatuses seem taxing at best, and near-impossible, at worst. To effectively navigate through these polarized loci, she must identify ideologies that in turn seek “affective liberatory sances” in relation to the dominant social order (43). In a kind of performative contradiction, she must marshall the knowledge necessary to “break with ideology” while speaking within it. Chicana Studies scholar, Chela Sandoval, describes this dual movement as “meta-ideologizing”: the appropriation of hegemonic ideological forms in order to transform them (82). Nuestros padres se subieron encima de La Bestia, y por eso somos pasageros a ese tren. Y ya, dentro su pansa, tenemos que ser vigilantes cuando plantamos las bombas. In Methodology of the Oppressed, Sandoval schematizes this oppositional consciousness around five principle categories: “equal rights,” “revolutionary,” “supremacist,” “separatist,” and “differential.” Taken by themselves, the first four modes appear mutually exclusive, incapable of occupying the same plane, until a fifth pillar emerges. Cinematographic in nature, differential consciousness, as Sandoval defines it, is “a kinetic motion that maneuvers, poetically transfigures, and orchestrates while demanding alienation, perversion, and reformation in both spectators and practitioners” (44). For Sandoval, then, differential consciousness is a methodology that privileges an incredible sense mobility, one reaching artistic sensibilities. Our fourth and final analytic of movement serves an apt example of this dual meaning. Lexically speaking, ‘movement’ may be regarded as a political mobilization of aggrieved populations (through sustained efforts), or the process of moving objects (people or otherwise) from one location to another. Praxis-wise, it is both action and ideal, content and form. Thus, an ethnic poetics must be regarded less as a series of stanzas, shortened lyric, or even arrangement of language, but as a lens through which peripheralized peoples kaleidecope ideological positions in an “original, eccentric, and queer sight” (43). Taking note of the advantages of postponing identifications, the thesis stands its ground on the term ethnopoet. Its abstraction is not dewey-eyed philosophy, but an anticipation of poetic justice, of what’s to come from callused hands. This thesis is divided into 7.5 chapters. The first maps out the ethnopoet’s cartographies of struggle. By revisiting that alleged Tío Tomas, Richard Rodriguez, we unearth the tensions that negatively, deny citizenship to one silo, but on the flipside, engender manifold ways of seeing, hearing, and moving . The second, through George Jackson’s prison memoirs, pans out from this ethnography of power, groping for an apparatus that feigns an impervious prestige: ‘the aesthetic regime of coercion.’ In half-way cut, the thesis sidesteps to spic into existence, formally announcing, through Aime Cesaire, myself, and Pedro Pietri, the poeticization of trauma. Such uplift denies New Age transcendence of self, but a rehearsal of our entrapment in these mortal envelopes. Thirdly, conscious of the bleeding ethnic body, we cut open the incipient corpse to observe her pathologist. Her native autopsies offer the ethnic body’s posthumous recognition, the ethnopoetics ability to speak for and through the dead. Chapter five examines prolific black artists—Beyonce and Kendrick Lamar—to elide the circumvention of their consumption via invoking radical black hi/her-stories, ones fragmenting the black body. Sixth, the paper compares the Black Power Salute of the 1968 Mexico City Olympics to Duke’s Mi Gente Boycott of their Latino Student Recruitment Weekend. Both wielded “silent gestures,” that shrewdly interfered with white noise of numbed negligence. Finally, ‘taking the mask off’ that are her functionalities, the CODA expounds on ethnopoet’s interiority, particularly after the rapid re-calibration of her politics. Through a rerun of El Chavo del Ocho, one of Mexican television’s most cherished shows, we tune into the heart-breaking indigence of barrio residents, only to marvel at the power of humor to, as Friday’s John Witherspoon put it, “fight another day.” This thesis is the tip of my tongue. Y por una vez, déjala que cante.

Seawater carbonate chemistry, pigments and biological processes during experiments with coralline alga Corallina sessilis

Previous studies have shown that increasing atmospheric CO2 concentrations affect calcification in some planktonic and macroalgal calcifiers due to the changed carbonate chemistry of seawater. However, little is known regarding how calcifying algae respond to solar UV radiation (UVR, UVA+UVB, 280-400 nm). UVR may act synergistically, antagonistically or independently with ocean acidification (high CO2/low pH of seawater) to affect their calcification processes. We cultured the articulated coralline alga Corallina sessilis Yendo at 380 ppmv (low) and 1000 ppmv (high) CO2 levels while exposing the alga to solar radiation treatments with or without UVR. The presence of UVR inhibited the growth, photosynthetic O2evolution and calcification rates by13%, 6% and 3% in the low and by 47%, 20% and 8% in the high CO2 concentrations, respectively, reflecting a synergistic effect of CO2 enrichment with UVR. UVR induced significant decline of pH in the CO2-enriched cultures. The contents of key photosynthetic pigments, chlorophyll a and phycobiliproteins decreased, while UV-absorptivity increased under the highpCO2/low pH condition. Nevertheless, UV-induced inhibition of photosynthesis increased when the ratio of particulate inorganic carbon/particulate organic carbon decreased under the influence of CO2-acidified seawater, suggesting that the calcified layer played a UV-protective role. Both UVA and UVB negatively impacted photosynthesis and calcification, but the inhibition caused by UVB was about 2.5-2.6 times that caused by UVA. The results imply that coralline algae suffer from more damage caused by UVB as they calcify less and less with progressing ocean acidification.

Paleoecology, Diagenesis and Biological Affinity of Tetradiids in the Upper Ordovician (Sandbian) Black River Group of the Kingston Area, Ontario, Canada

Tetradiids are a group of colonial, tubular fossils that occur globally in Middle to Upper Ordovician strata. Tetradiids were first described as a type of tabulate coral; however, based on their four-fold symmetry, division, and presence of a central-sparry canal, they were recently reinterpreted as a florideophyte rhodophyte algae, a reinterpretation that is tested in this thesis. This study focused on understanding the affinity and taphonomy of this order of fossil. Research was conducted by stratigraphic and petrographic analyses of the Black River Group in the Kingston, Ontario region. Tetradiid occurrences were divided into fragment or colonial, with three morphologies of tetradiids described (Tetradium, Phytopsis and Paratetradium). Morphology is specific to depositional environment, with compact Tetradium consistently within ooid grainstones and open branching Phytopsis and chained Paratetradium consistently within mudstones. Two types of patch reefs were recognized: a Paratetradium bioherm, and a Paratetradium, Phytopsis, stromatolite bioherm. The presence of bioherms implies that tetradiids were capable of hypercalcifying. Preservation styles of tetradiids were investigated, and were compared to brachiopods, echinoderms, mollusks, and ooids. Tetradiids were preferentially preserved as molds and demonstrated complete dissolution of skeletal material. Rare specimens, however, demonstrated preserved horizontal partitions, central plates, and a double wall. Skeletal molds were filled with either calcite spar, mud or encrusted by a cryptomicrobial colony. Both calcitic and aragonitic ooids were discovered. The co-occurrence of aragonitic ooids, aragonitic crytodontids, and the evolution of aragonitic, hypercalcifying tetradiids is interpreted as representing the geochemical favoring of aragonite and HMC in a time of global calcite seas. The geochemical favoring of aragonite is interpreted to be independent to global Mg: Ca ratios, but was the result of increased saturation levels and temperature driven by high atmospheric pCO2. Based on the presence of epitheca, tabulae, septa, and the commonality of growth forms, tetradiids are interpreted as an order of Cnidaria. The evolution of an aragonitic skeleton in tetradiids is interpreted to be the result of de novo acquisition of a skeleton from an unmineralized clade.