Infectious disease has always been and will continue to be a heavy burden on human society worldwide. Terrestrial actinobacteria, notable as a source of antibiotics, have been well investigated in the past. In constrast, marine actinobacteria, especially sponge-associated species, have received much less attention and isolates are sparse. With the aim of studying and discovering novel marine actinobacteria, 11 different species of sponges were collected from the Central Red Sea in Saudi Arabia and cultured with three different types of media. 16S rRNA gene-sequencing revealed that among all 75 isolated bacterial strains 13 belonged to the order actinomycetales. These 13 actinomycetes fall into four different families and can be assigned to six different genera. Antibiotic activity tests using disc diffusion assay were performed against Gram-positive bacteria (Bacillus sp.), Gram-negative bacteria (Escherichia coli), fungi (Fusarium sp.) and West Nile virus NS3 protease. Nine strains presented different level of bioactivity against these pathogens. These findings provide evidence that actinomycetes are presented in marine sponges and that they have the potential to be good candidates in the search for new effective antibiotic, antifungal, and antiviral compounds.

No description available.

No description available.

The work of this dissertation examined the secondary metabolites of several blooms of the marine cyanobacterium Lyngbya collected in Guam and Florida with an emphasis on the isolation and structure elucidation of novel biologically active compounds. The introduction in Chapter One provides a brief history of marine natural products, a description of cyanobacteria and a summary of peptides isolated from Lyngbya collected in the Caribbean. In Chapter Two, a bioassay-guided fractionation of a Floridian collection of Lyngbya polychroa led to the isolation and structural determination of the cytotoxin desacetylmicrocolin B and the known compounds microcolins A and B. The structures were established by nuclear magnetic resonance (NMR) spectroscopic analysis. All three compounds inhibited the growth of cancer cell lines HT-29 and IMR-32 at nanomolar concentrations. Microcolins A and B were found to have little activity in the ecological assay against the marine fungus Dendryphiella salina. Chapter Three describes the isolation and structure elucidation of the glycosidic, acyl proline derivative tumonoic acid J from a sample Lyngbya sp. collected in Guam. The planar structure was determined by 1D and 2D NMR spectroscopy in conjunction with high resolution-mass spectrometry (HR-MS) data. Tumonoic acid J showed moderate activity in the ecological assay against the marine fungus D. salina. In Chapter Four, NMR-guided fractionation of a Floridian sample of Lyngbya majuscula led to the isolation of two novel cyclic peptides porpoisamides A and B. The planar structures were determined by 1D and 2D NMR spectroscopy with HR-MS data. The absolute configurations of these two compounds were defined through chiral chromatographic methods and derivatization techniques. / The porpoisamides showed only moderate activity in cytotoxicity assays against cancer cell lines HCT-116 and U2OS. Finally, Chapter Five examines a potential ecological role of compounds isolated from marine cyanobacte ria. These secondary metabolites may function as chemical defenses against competing microorganisms within marine environments. Compounds isolated from cyanobacteria were tested for anti-fungal activity against the saprophytic marine fungus D. salina. Three of the six compounds tested produced inhibitory activity at or below their natural concentration. / by Theresa Meickle. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The ability to raise an immune response is essential for all life. Despite this, the evolution of immune systems is poorly understood, as immune genes confound many bioinformatic analyses. This is driven by the rapid rates at which immune genes evolve due to the incessant arms race between host and pathogen often causing standard phylogenetic approaches to fail to accurately model the evolutionary history of immune gene families. Many phylogenetic lessons have been learned since the dawn of the phylogenomics era however, and genome sequences of non-model organisms have now been assembled, permitting improved immune gene detection and hence taxon sampling. In this thesis, I have paired sophisticated phylogenomic tools, including outgroup-free rooting methods, and substitution models that account for structural and functional constraints on protein evolution, with new genome and transcriptome sequence data from taxa that allow inference of the ancestral immune state in vertebrates and animals. Using this approach, I have managed to identify the origins of several key immune genes and families. My results support ancestral complexity in the genes that regulate the functioning of vertebrate adaptive immune systems. My findings also support the presence of a complement system, a front-line innate immune defence, in the ancestor of all animals. I show that this system later underwent a period of major remodelling early in vertebrate evolution, generating novel complement systems in at least three major vertebrate taxa. It is clear from my findings that combining sophisticated phylogenetic models with enriched taxon sampling represents a powerful approach with which to gain understanding of the evolutionary history of the immune system, even in the face of gene loss and the inherent complexity of immune gene evolution.

Natural products have been a fundamental source of medicinal scaffolds for decades; with sixty percent of marketed drugs. Many synthetic chemists are focused on synthesizing potent and nontoxic compounds for pharmaceutical targets, however, nature is still proving to be a source of new bioactive compounds. Produced by the host organism for defense, reproduction and communication, secondary metabolites also demonstrate promising bioactivity against human pathogens. Hence, natural product chemists continue their quest for new leads. As a continuation of these efforts, this thesis attempts to explore fungi and sponges for new chemistry, and ultimately, new drug candidates. Antarctica is largely untapped; hence herein two Antarctic sponges were chemically investigated. This resulted in isolation and characterization of two metabolites. Concurrently, chemical investigation of fungus, from Floridian mangrove species, resulted in the isolation of two structurally diverse metabolites. Further, a dereplication process was applied to MPLC fractions, which lead to the identification of known metabolites and mycotoxins. This enabled prioritization of fractions for future studies.

"March 2002" / Addendum inserted at back. / Includes bibliographical aspects (leaves 105-117) / xi, 117 leaves : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2002

Specimens of freshwater bryozoans (Ectoprocta) and sponges (Porifera: Spongillidae), two of the most poorly known faunal groups in Canada, were obtained from various locations in Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland. A total of 14 species of bryozoans and 15 species of sponges were identified. In 31 cases, these species were recorded from a province for the first time. Species new to Canada include the bryozoans Lophopodella carteri, Plumatella orbisperma, and Pottsiella erecta, and the sponges Radiospongilla crateriformis, Spongilla aspinosa, and Trochospongilla horrida. The morphology, taxonomy, distribution, and ecology of each species are examined. Several taxonomic revisions are made. Eunapius mackayi and Plumatella orbisperma are redescribed. Spongilla heterosclerifera, considered an endangered species, is shown to be a species mixture. Taxonomic keys to Eastern Canadian species of freshwater bryozoans and sponges are presented. New limits of tolerance to pH, calcium and magnesium levels, and water temperature are established for several species.

Thesis (M.A.)--Georgia Southern University, 2008. / "A dissertation submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Under the direction of Daniel F. Gleason. ETD. Electronic version approved: May 2008. Includes bibliographical references (p. 53-61) and appendices.

Thesis (Ph.D.)--University of North Carolina Wilmington, 2008. / Title from PDF title page (viewed May 27, 2009) Includes bibliographical references (p. 73-76)