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Optimierung der biosorptiven Schwermetallentfernung unter Verwendung von immobilisierter AlgenbiomasseWilke, Andreas. January 2001 (has links) (PDF)
Berlin, Techn. Univ., Diss., 2001. / Computerdatei im Fernzugriff.
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Responses of desiccation-tolerant cyanobacteria to environmental extremes /Fleming, Erich David, January 2006 (has links)
Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 115-129). Also available for download via the World Wide Web; free to University of Oregon users.
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Cloning and biochemical characterization of the hectochlorin biosynthetic gene cluster from the marine cyanobacterium Lyngbya majusculaRamaswamy, Aishwarya V. 02 June 2005 (has links)
Cyanobacteria are rich in biologically active secondary metabolites, many of
which have potential application as anticancer or antimicrobial drugs or as useful
probes in cell biology studies. A Jamaican isolate of the marine cyanobacterium,
Lyngbya majuscula was the source of a novel antifungal and cytotoxic secondary
metabolite, hectochlorin. The structure of hectochlorin suggested that it was derived
from a hybid PKS/NRPS system. Unique features of hectochlorin such as the
presence of a gem dichloro functionality and two 2,3-dihydroxy isovaleric acid
prompted efforts to clone and characterize the gene cluster involved in hectochlorin
biosynthesis.
Initial attempts to isolate the hectochlorin biosynthetic gene cluster led to the
identification of a mixed PKS/NRPS gene cluster, LMcryl, whose genetic architecture
did not substantiate its involvement in the biosynthesis of hectochlorin. This gene
cluster was designated as a cryptic gene cluster because a corresponding metabolite
remains as yet unidentified. The expression of this gene cluster was successfully
demonstrated using RT-PCR and these results form the basis for characterizing the
metabolite using a novel interdisciplinary approach.
A 38 kb region putatively involved in the biosynthesis of hectochlorin has also
been isolated and characterized. The hct gene cluster consists of eight open reading
frames (ORFs) and appears to be colinear with regard to hectochlorin biosynthesis.
An unusual feature of this gene cluster includes the presence of a ketoreductase
domain in an NRPS module and appears to be the first report of such an occurrence in
a cyanobacterial secondary metabolite gene cluster. Other tailoring enzymes present
in the gene cluster are two cytochrome P450 monooxygenases and a putative
halogenase. The juxtaposition of two ORF's with identical modular organization
suggests that this gene cluster may have resulted from a gene duplication event.
Furthermore, biochemical characterization of two adenylation domains from this
cluster strengthens its involvement in the biosynthesis of hectochlorin. / Graduation date: 2006
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Biosynthetic investigations of two secondary metabolites from the marine cyanobacterium Lyngbya majusculaRossi, James V. 06 March 1997 (has links)
Marine cyanobacteria have been shown to produce a variety of biologically active
and stucturally diverse secondary metabolites. These compounds are of interest to natural
products researchers mainly because of their potential application as biomedicinals,
biochemical probes, and agrichemicals.
The metabolic pathways utilized by the cyanobacterium Lyngbya majuscula to
generate curacin A, a potent antimitotic and its cometabolite, the molluscicidal barbamide,
have been studied. Application of methods including radioisotope and stable isotope
labeling have revealed the role of acetate and the amino acids methionine, valine, cysteine,
and leucine as potential precursors in the biosynthesis of curacin and barbamide.
An analytical technique based upon GC-EIMS methodology has also been
developed to monitor the production levels of curacin A from cultures of Lyngbya
majuscula with respect to growth. This method which makes use of the thiazole analog of
curacin A, curazole as an internal standard, has also been preliminarily applied to the
curacin A production in response to environmental factors associated with changes in
geographical locations at or near sites where the original collections of the cyanophyte
were made in Curacao, Netherlands Antillies. This was performed by a series of transplantation experiments envolving high and trace curacin A producing strains of L. majuscula.
Interest in the bioactive profile of curacin A prompted a pilot scale up of the cultured tissue for isolation of the metabolite. These efforts provided a framework of methods that can be used industrially to obtain large quantites of the compound to meet possible future pharmaceutical or dignostics demands. / Graduation date: 1997
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Natural products studies of the marine cyanobacteria Lyngbya semiplena and Lyngbya majusculaHan, Bingnan 03 June 2005 (has links)
This thesis details my investigations of marine cyanobacterial natural
products that resulted in the discovery of eighteen new secondary metabolites.
Isolation and characterization of these unique molecules were carried out using
different chromatographic techniques and by careful analyses of 1D and 2D NMR
data, respectively.
Preliminary bioassays of the crude organic extract of the marine
cyanobacterium Lyngbya semiplena collected from Papua New Guinea in 1999,
showed good activity in the brine shrimp toxicity model at 10 ppm. Guided by this
assay, seven new anandamide-like fatty acid amides, semiplenamides A to G,
together with four cyclic depsipeptides, wewakpeptins A to D, were identified. Due
to the structural resemblance of the novel ethanolamide derivatives
(semiplenamide A-G) with anandamide, (N-arachidonoyl-ethanolamine), an
endogenous agonist of cannabinoid receptors compounds, semiplenamide A-G
were tested on the well characterized proteins of the endocannabinoid system: 1)
the "central" cannabinoid CB₁ receptors; 2) the anandamide membrane transporter
(AMT), which is responsible for anandamide cellular uptake; and 3) the fatty acid
amide hydrolase (FAAH), which catalyses anandamide hydrolysis. Three showed
modest potency in displacing radiolabeled anandamide from the cannabinoid
receptor (CB₁), and one was a modest inhibitor of the anandamide membrane
transporter (AMT). The wewakpeptins were tested for cytotoxicity to NCI-H460
human lung tumor and neuro-2a mouse neuroblastoma cells. Intriguingly,
wewakpeptin A and B were approximately 10-fold more toxic than C and D to
these cell lines.
Lyngbya majuscula has been recognized as a chemically and biologically
rich strain. Five new lyngbyabellin analogs, lyngbyabellins E-I, along with the
known compound dolabellin, originally isolated from sea hare Dolabella auricularia,
were identified from a 2002 Papua New Guinea collection of the marine
cyanobacterium Lyngbya majuscula. The lyngbyabellins were tested for
cytotoxicity to NCI-H460 human lung tumor and neuro-2a mouse neuroblastoma
cells and had LC₅₀ values between 0.2 and 4.8 μM. Intriguingly, lyngbyabellin E
and H appeared to be more active against the H460 cell line with LC₅₀ values of
0.4 μM and 0.2 μM, respectively, compared to LC₅₀ values of 1.2 and 1.4 μM in the
neuro-2a cell line. Lynbyabellin I was the most toxic to neuro-2a cells (LC₅₀ 0.7
μM), whereas lyngbyabellin G, was the least cytotoxic of all compounds to either
cell line. On the basis of this limited screening, it appears that lung tumor cell
toxicity is enhanced in the cyclic representatives, and overall potency is increased
in those containing an elaborated side chain.
Additionally, two new cytotoxins, aurilides B and C, which are closely
related to aurilide, originally isolated from the sea hare Dolabella auricularia, have
been identified from the same extract where the lyngbyabellins E-I were isolated.
Aurilides B and C were tested for cytotoxicity to NCI-H460 human lung tumor and
neuro-2a mouse neuroblastoma cells. Interestingly, aurilide B was approximately
4-fold more toxic than C to these cell lines. The LC₅₀ for Aurilide B was 0.01 μM
and 0.04 μM for neuro-2a and H460 cells, respectively, and 0.05 μM and 0.13 μM,
respectively, for aurilide C. Aurilide B was evaluated in the NCI 60 cell line panel
and found to exhibit a high level of growth inhibition in leukemia, renal, and
prostate cancer cell lines with a GI₅₀ less than 10 nM. Aurilide B showed net tumor
cell killing activity in the NCI's hollow fiber assay, an in vivo model for assessing a
chemical's anticancer activity. / Graduation date: 2006
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Novel bioactive secondary metabolites from the marine cyanobacterium Lyngbya majusculaWu, Min, 1963- 13 September 1996 (has links)
Marine algae have been recognized as a rich resource of new
and unusual organic molecules with diverse biological properties.
The current need to develop new antifungal, anticancer, antibiotic
and antiviral drugs has led to an intense research effort into the
discovery, isolation and structure determination of potential
medicinal agents from marine algae.
In the past two years, I have participated in a drug discovery
program designed for antitumor, antifungal and other agents of
potential pharmaceutical utility from the marine cyanobacterium
Lyngbya majuscula. This research utilized modern chromatographic
and spectrochemical techniques including 2D NMR spectroscopy.
Brine shrimp toxicity guided the fractionation that led to the
discovery of the biologically active compound kalkitoxin from a
Curacao Lyngbya majuscula extract. The structure of this new
thiazoline ring-containing lipid was determined spectroscopically
by interpretation of 2D-NMR experiments, including heteronuclear
multiple quantum coherence (HMQC), heteronuclear multiple-bond
coherence spectroscopy (HMBC) and ��H-��H COSY at room
temperature and elevated temperature. Kalkitoxin shows modest
molluscicidal toxicity, good brine shrimp toxicity and extremely
potent ichthyotoxicity.
From the same extract of Lyngbya majuscula, I also isolated
two other secondary metabolites, malyngamide J and malyngamide
L. The structures of these new compounds, including
stereochemistry, were determined by spectroscopic techniques
including 2D-NMR experiments and by comparison with other
known malyngamides. / Graduation date: 1997
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Novel secondary metabolites from a Madagascar collection of Lyngbya majusculaNannini, Christopher J. 19 June 2002 (has links)
Graduation date: 2003
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Marine chemical ecology the search for sequestered and bioactive compounds in the sea hares Dolabrifera dolabrifera and Stylocheilus striatus and in their preferred food, the cyanobacterium, Lyngbya majuscula /Clark, Kathryn Elizabeth. January 1900 (has links)
Thesis (M.Sc.). / Written for the Dept. of Plant Science. Title from title page of PDF (viewed 2008/07/29). Includes bibliographical references.
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Optimierung der biosorptiven Schwermetallentfernung unter Verwendung von immobilisierter AlgenbiomasseWilke, Andreas. Unknown Date (has links)
Techn. Universiẗat, Diss., 2001--Berlin.
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Biomasses et compositions relatives des communautés de macroinvertébrés associées à différents types d'habitats au lac Saint-Pierre (Québec, Canada)Tourville Poirier, Anne-Marie January 2009 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
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