The pathway of seawater ammonium assimilation and influence of light on amino acid synthesis remain unresolved in cnidarian symbioses. Labeled ammonium (10 μM 15NH4Cl) in seawater was used to trace the pathway of the incorporation into amino acids in host tissue, Zoanthus sp., and zooxanthellae, Symbiodinium microadriaticum. Freshly isolated zooxanthellae were exposed to 20 μM 15NH4Cl with coral homogenate to evaluate the role of host factors on amino acid synthesis. High performance liquid chromatography and mass spectrometry was used to measure percent labeling and concentrations of amino acids. In zooxanthellae, ammonium was assimilated into glutamine likely via glutamine synthetase and into glutamate via glutamine 2-oxoglutarate amidotransferase. Interrupting photosynthesis with DCMU did not inhibit glutamine and tryptophan synthesis however reduced the 15N-enrichment of glutamate, aspartate, and ornithine in zooxanthellae, as well as arginine, ornithine, and lysine in host tissue. Coral homogenate had little effect on the 15N-enrichment of glutamine, aspartate, and alanine in freshly isolated zooxanthellae. Evidence is presented to support the uptake of ammonium ions and data shows that glutamine and not glutamate is translocated to the coral host.

The difference in the ability of plants to obtain resources has been used to predict the competition outcomes. Competitive interactions between plants can be influenced by trophic interactions. If mycorrhizae increase the growth of inferior competitors, then it can prevent competitive exclusion. I examined the effect of mycorrhizae on competitive interactions and found that inferior competitors had slow growth in the absence of mycorrhizae, but greater growth with mycorrhizae. By providing greater growth responses to inferior versus superior competitors, mycorrhizae promoted coexistence. In a separate experiment, I looked at the effects of whole soil biota on competitive ability. Coexistence can occur if dominant competitors experience negative feedback and or if inferior competitors experience positive feedback. I examined Plantago lanceolata L. specific feedback effects on competitive ability of 21 co-occurring species. I found that feedback effects did not affect hierarchies, and that positive feedback did not improve species competitive ability. / NSERC (Natural Science and Engineering Research Council), University of Guelph, Queen Elizabeth II Graduate Scholarship for Science and Technology

Magistrantūros studijų baigiamasis praktinis-kūrybinis projektas, kuriamas naujoje aplinkoje ar pritaikomas jau susiklosčiusioje paveldo situacijoje, susijęs su integravimo aplinkoje ir kontekstualumo problemomis. Architektūrinis ansamblis, derantis su instaliuotu meno kūriniu ne tik vizualiai, bet ir konceptualiai, papildomas lygiagrečiai veikiančia patirtimi, yra suvokiamas kompleksiškai. Svencelės jėgos aitvarų ir burlenčių centro architektūrinis ansamblis pasižymi savitu požiūriu į gamtinę situaciją. Svencelės jėgos aitvarų ir burlenčių centras – rytinėje Kuršių marių pakrantėje įsikūrusi poilsiavietė, įrengta jūriniuose konteineriuose. Teritorijoje įrengta 33 konteinerių, iš kurių 23 yra gyvenami, sutvarkyta aplinka, praplatintas tvenkinys, kuriame sukurta vandenlenčių sporto infrastruktūra. Savita derme su gamta pasižymi darnus architektūros instaliavimas. Šiuolaikiniu požiūriu paremta patirtis leidžia suvokti šį kompleksą kaip lygiagrečiai su gamta egzistuojantį ir deramą pagarbą išlaikantį statinį. Objekto realizacijai panaudoti pažangūs, gamtinės aplinkos nepažeidžiantys sprendimai. Adekvatus požiūris į supančią aplinką ir objekto funkciją, ko gero, yra stipriausias šio projekto aspektas. Svarbiausia – suformuota aplinka, nevaržanti patyrimo pojūčių. Visa komplekso kompozicija dėliojama atsižvelgiant į infrastruktūros patogumą. Atsižvelgiant į architektūrinio komplekso paskirtį svarbiausia šiame komplekse išlieka pagarba gamtai, taigi svarbi idėja, jog pastatai gali... [toliau žr. visą tekstą] / Master's degree final practical-creative project, created a new architectural situation is related to the integration of the environment and the contextual issues. Architectural ensemble, negotiating with an installed piece of art, not only visually, but also conceptually, is perceived holistically. Svencelė kite and windsurfing center architectural ensemble has its own approach to the natural situation. Realization of the object is used the advanced solutions without damaging the natural environment. The complex is equipped with 33 containers, 23 of them are residential. There is an environment for active sports, is widened pond, where is a wakeboarding sports facilities. Adequate treatment of the surrounding environment and the object function is the strongest part of this project. In glass object designing process in the natural - architectural context, the most important factor in the way of expression is ethnic - cultural history of curonian region, the complex function and geographic location behavior - constantly blowing wind. Glass object - a weathercock concept dictated by the wind religious importance in the region. According to local tradition weathervane connects the two experiences: the old etnical and the new architectural expressions. The object looks like a sail or new age weathervane. Composed of several layers of glass overlaps and creates optical illusions of changing, wind-blown form creates additional movement. Glass object is composed of three... [to full text]

Formuojant architektūros ir dailės ansamblį, lemiamu faktoriumi tampa vienos meno srities su kita tarpusavio santykis, priklausomai nuo to, ar jis labiau juslinis ar racionalus, hierarchinis ar ne, akcentuojantis skirtumus ar juos niveliuojantis. Šiuolaikinėje XX a. pabaigos – XXI a. pradžios architektūroje stipriai jaučiama moderniausiųjų menų ir ideologijų įtaka. Pastatas tampa tarpdisciplininiu meno objektu. Sujungiamos menininko ir architekto idėjos, darbo eigoje leidžiančios suvokti architektūrą, kaip skirtingų menininkų derybų objektą, įprasminantį skirtingus kūrybinius pajėgumus. Architektūra įgauna konceptualią formą ir išraišką, kur ypač svarbus architektūrinės raiškos elemento vaidmuo tenka pastato eksterjerams (fasadams). Autonomiška pastato fasado (paviršiaus) traktuotė leidžia daug platesnę raiškos priemonių galimybę. Pastato apvalkalas savo funkcija supanašėja su oda ar rūbu, gyvuoja autonomiškai nuo vidaus struktūros, todėl gali būti dinamiškas, kintantis, daugiasluoksnis, bet tuo pat metu ir monumentalus. Teorinį darbą sudaro trys dalys. Pagrindžiama šiuolaikinės architektūros pastato kaip integralaus kūrinio samprata, aptariama pagrindinė postmodernių fasadų vizualaus suaktyvinimo priemonė - stiklo sąveika su šviesa. Aptariami konkretūs plokščių architektūrinių paviršių suaktyvinimo būdai bei situacija Lietuvoje. Pateikiami objektų pavyzdžiai, apžvelgiant architektūrinių paviršių raiškos galimybes, nagrinėjami panaudojimo tikslai ir rezultatai... [toliau žr. visą tekstą] / In the late XXth – XXIst century architecture strongly felt influence of conteporary arts and ideologies. where essential architectural element of role definition of the building's exterior (facade). Architecture becomes a conceptual meaning in form and expression, where an important part of the architectural expression takes architectural surfaces (facades). Building envelope (surface) in his function converge with the skin or clothing, exists independently of the internal structure, so it can be dynamic, evolving, multi-layered, but at the same time monumental. The theoretical work consists of three particural parts. Describes modern building as an integral part of architectural ensemble, discusses the main postmodern facades visual activation tool - glass interaction with light. Specifies the architectural surface activation techniques and the situation in Lithuania. Describes the architectural objects, overview of the expression capabilitys of the architectural surface. Analyzed the application of architectural glass objects in the environment trends, discusses the future prospects. The third part is devoted to analysis of the particular architectural ensemble and the glass object proposal.

No description available.

The genera Spongia and Hippospongia include all of the commercially important bath sponges of the Caribbean fishery. This study examined the uniform presence of immense symbiotic bacterial populations of four of these species: Hippospongia lachne, Spongia barbara, S. cheiris and S. graminea. The nutritional characteristics and antibiotic sensitivities of bacteria isolated from the four species were also examined. A combined light and transmission electron microscopic investigation outlined the reproductive processes and larval development, behaviour, settlement and metamorphosis in these four species. / Symbiotic bacteria in these four sponge species are specific to the sponges and different from ambient seawater bacteria. Populations of intercellular bacteria within the tissues of these sponges are greater than those of ambient seawater. A variety of morphologically different types of sponge specific bacteria were observed. The symbionts are not fastidious organism but utilize a variety of amino acids, carbohydrates and tricarboxylic acid cycle intermediates as sole carbon and energy sources for growth. The bacteria showed sensitivities to a variety of antibiotics but were not susceptible to fluid from the sponges. / These sponges are viviparous and probably dioecious. Egg production and larval development are localized in patches or "nurseries" of endosomal tissue. Statistical analyses of specific morphological characteristics of female reproductive elements have identified four specific stages in the process of oogenesis. Umbilici connect young and maturing embryos to the maternal mesohyl and are the pathway for extracellular transfer of intercellular symbiotic bacteria and other mesohyl substances. These bacteria were observed in the embryos and larvae of all four species. Oocytes and embryos develop asynchronously within a given individual. Spermatogenesis occurs synchronously within cysts by transformation of entire choanocyte chambers. Cysts develop asynchronously within an individual. Male gametes exhibit a bright yellow-white autofluorescence when excited with blue light (460-485 nm). Spermatozoa do not possess intermediate segments or acrosomes. / The incubated parenchymella larvae of these four species are ovoid with dark grey pigmentation and enlarged posterior regions encircled by a black pigmented ring of cells bearing long cilia. Laboratory behavioural studies indicate that free-swimming larvae display directional swimming with constant rotation and negative phototaxis. Larval behaviour probably reflects the ecological situation of adult populations. Larval settlement occurs 26-56 hours after release and involves the rapid formation of a basal lamella between the larvae and substrate. There is no evidence of substrate selection or orientation by larvae. Precocious development of choanocytes does not occur in the larvae or post-larvae of these four species.

Root symbioses with arbuscular mycorrhizal fungi and rhizobial bacteria share a common signaling pathway in legumes. Among the common symbiosis genes are CASTOR and POLLUX, the twin homologous genes in Lotus japonicus that encode putative ion channel proteins. Orthologs of CASTOR and POLLUX are ubiquitously present in both legumes and non-legumes, but their function in non-legumes remains to be elucidated. Here, we use reverse genetic approaches to demonstrate that the rice (Oryza sativa) ortholog of POLLUX, namely Os-POLLUX, is indispensible for mycorrhizal symbiosis in rice. Furthermore, we show that Os-POLLUX can restore nodulation, but not rhizobial infection, to a M. truncatula dmi1 mutant.

All animals exist in lifelong relations with a complement of bacteria. Because of the ubiquity of these symbioses as well as the derived biomedical applications, the study of both beneficial and pathogenic host-microbe associations has long been established. The monospecific light organ association between the Hawaiian sepiolid squid Euprymnascolopes and the marine luminous bacterium Vibrio fischeri has been used as a experimental model for the study of the most common type of animal-bacterial interaction, i.e., the association of coevolved Gram-negative bacteria with the extracellular apical surfaces of polarized epithelia. A fundamental step for understanding the mechanisms of host-symbiont associations lies in defining the genetic components involved; specifically defining changes in host gene expression. The studies presented in this dissertation identify and characterize V. fischeri-induced changes in host gene expression at both the transcript and protein level.

Abstract The age of an adult female mosquito is a critical determinant of its ability to transmit a range of human pathogens such as the dengue viruses. Since most pathogens require a relatively long period of development in their mosquito vector before they can be transmitted to a new host, only older insects are of epidemiological importance. It has been proposed that life-shortening strains of the inherited bacterial symbiont Wolbachia may be potentially useful to shift mosquito population age structure towards younger individuals, thereby reducing pathogen transmission without eradicating the mosquito population. However, life-shortening Wolbachia strains do not occur in mosquitoes naturally. To facilitate the evaluation of this potential strategy, the major aim of this project was to transfer a life-shortening Wolbachia strain, wMelPop, from the fruit fly, Drosophila melanogaster, to the dengue vector, Aedes aegypti. After successful transinfection, I then characterized the wMelPop infection in this mosquito species, and the associated phenotypic effects of this Wolbachia strain on several aspects of Ae. aegypti life-history. The horizontal transfer of the obligate intracellular bacterium Wolbachia pipientis between invertebrate hosts hinges on the ability of Wolbachia to adapt to new intracellular environments. Previous attempts to directly transfer wMelPop from D. melanogaster to Ae. aegypti have been unsuccessful, presumably due to mal-adaptation of wMelPop to this novel mosquito host. In an attempt to adapt wMelPop to the mosquito intracellular environment to facilitate transfer, we serially passaged this infection for 3 years in Aedes cell culture. After long-term serial passage in mosquito cell lines, wMelPop was then initially reintroduced into its native host, D. melanogaster, by embryonic microinjection to examine the phenotypic outcome of this process. The cell line-adapted wMelPop strains were characterized by a loss of infectivity when reintroduced into Drosophila, grew to decreased densities, and had reduced abilities to cause life-shortening infection and cytoplasmic incompatibility (CI), when compared to the original wMelPop strain. These results were suggestive of adaptation of this Wolbachia strain to the mosquito intracellular environment. Subsequently, we successfully established wMelPop in Ae. aegypti using embryonic microinjection. Two independently transinfected Ae. aegypti lines, PGYP1 and PGYP2, were generated. Analogous to infection in Drosophila, the presence of wMelPop in both of these lines halved adult mosquito lifespan under a range of laboratory conditions. The new association is stable, and wMelPop is maternally inherited with high fidelity across Ae. aegypti life span. It is capable of inducing near perfect CI that does not diminish as male Ae. aegypti age, which should facilitate its invasion into natural field populations and persistence over time. Fecundity assays using young PGYP1 females revealed that wMelPop infection induced minimal costs for reproductive fitness for females during their first gonotrophic cycle. The phenotypic effects of wMelPop on several aspects of Ae. aegypti life-history were additionally characterized. Overall, minor costs of wMelPop infection for pre-imaginal survivorship, development and adult size were observed. However, wMelPop infection decreased the viability of quiescent Ae. aegypti eggs over time. Similarly, the reproductive fitness of wMelPop-infected Ae. aegypti females declined with age. These results revealed a general pattern associated with wMelPop pathogenesis in Ae. aegypti, where host fitness costs incurred by this infection increase during aging of both immature and adult life-history stages. We also discovered that wMelPop-infected Ae. aegypti have a reduced ability to utilise blood from non-human hosts for egg development. Blood feeding by wMelPop-infected females on mouse, guinea pig or chicken hosts resulted in a near complete abolishment of reproductive output associated with both a decline in the numbers of eggs oviposited as well as the hatching rate of successfully laid eggs. In contrast, the reproductive output of wMelPop-infected females fed human blood was normal, with intermediate effects observed with other vertebrate blood sources. Removal of Wolbachia from mosquitoes using antibiotic treatment restored egg development to standard levels on all blood sources. Further blood feeding assays over two reproductive cycles definitively illustrated a nutritional interaction between host blood source and egg development in wMelPop-infected Ae. aegypti. This dramatic phenotype may provide new insights into the nutritional basis of mosquito anthropophily. The results presented in this thesis highlight several important parameters required to theoretically model the infection dynamics of wMelPop, and its potential impacts on Ae. aegypti populations. Moreover, the successful establishment of wMelPop in Ae. aegypti forms the primary basis for further field-based evaluations, which will ultimately determine the viability of this Wolbachia-based strategy as an applied tool to reduce dengue transmission.

Hydrolytic enzymes degrade macromolecules into smaller components. These enzymes are important in fungal nutrition and have been implicated in the pathogenicity and virulence of pathogenic fungi towards their hosts. However, it is unknown if hydrolytic enzymes play important roles in mutualistic symbioses. In this study, the function of two different classes of hydrolytic enzymes was examined in the mutualistic symbiosis between the fungal endophyte Epichloë festucae and perennial ryegrass (Lolium perenne cv. Nui). Nine members of a gene family encoding subtilisin-like proteases were identified in E. festucae. The prt2, prt3 and prt5 genes encode putative extracellular proteins belonging to the proteinase K subfamily 1, and prt1 and prt6 encode putative extracellular proteins belonging proteinase K subfamily 2. The prt7 and prt8 genes encoded pyrolysin-like enzymes from subfamilies 1 and 2. The prt4 gene encodes a putative vacuolar protease, while the kex2 gene encodes a putative proprotein convertase. Expression analysis showed that the prt1, prt3, prt5, prt4 and kex2 genes, but not the prt2 gene, were expressed in culture. The prt1 and prt3 genes appeared to be up-regulated in planta compared to culture. The function of prt1 and prt2 in the symbiotum between E. festucae and perennial ryegrass was characterised by expressing these genes under the control of the Aspergillus nidulans gpdA or the E. festucae F11 ltmM promoters. No major differences in hyphal or plant morphology were observed between symbioses containing wild type E. festucae or endophyte strains containing the prt1 or prt2 transgenes. The gcnl gene, which encodes a β-1,6-glucanase, was identified immediately downstream of the prt2 gene. The function of the gcnl gene was characterised by gene replacement and testing the phenotype during growth in culture and in planta. E. festucae ∆gcnl strains grew normally on glucose-containing media. On media containing the β-1,6-glucan pustulan, ∆gcnl strains did not form aerial hyphae or hydrolyse pustulan, which the wild type strain did. This phenotype was partially complemented by growth of the ∆gcnl mutant in close proximity to wild type strains, and fully complemented by insertion of the gcnl gene. This suggests that the gcnl gene encodes the major β-1,6-glucanase activity of E. festucae.