Louda, J. William

Freshwater harmful algal blooms (HABs) are increasing in severity and frequency. These blooms are devastating to the communities surrounding these bodies of water due to their numerous health, economic, and environmental impacts (Hallegraeff et al. 1995; Smith 2003; O’Neil et al. 2012; Bláha et al. 2009; V. H. Smith et al. 1999). In Florida, runoff containing fertilizers, human wastes, or industrial wastes contribute to the eutrophication in these lakes and contribute to these freshwater blooms (Val H. Smith 2003; Heisler et al. 2008; O’Neil et al. 2012). M. aeruginosa, a toxic cyanobacterium, often devastates Lake Okeechobee. M. aeruginosa die off creates anoxic conditions and produces a toxin that causes major environmental loss. This project is aimed to increase knowledge on how organic phosphorus compounds affect the growth of the axenic M. aeruginosa and investigate the postulated interactome (Cook et al. 2020). Through these experiments, it was shown that axenic M. aeruginosa cannot utilize organic phosphorus compounds and therefore shows no growth when grown in this media. This research is critical to furthering our understanding of the mechanisms behind these blooms and to mitigating them.

Eutrophication is an increase in primary plant nutrients (Nitrogen [N] and Phosphorus [P]) in oceans, estuaries and lakes. The consequences of eutrophication are harmful algal blooms (HABs), resulting in algal toxin production and the depletion of oxygen as the extensive biomass decays. P is often the limiting nutrient and is viewed as a significant environmental problem. Most of the excess P that enters aquatic ecosystems originates from anthropogenic sources such as fertilizers, sewage, animal wastes, compost, crop residues, and wastewater. Over time, one of the main reservoirs of P becomes organic P (Po). We investigated the chemical nature and dynamics of P in cyanobacteria, horse manure, stormwater treatment areas, and rice fields. To better understand the chemical nature of P, the identification of specific P compounds was required, which was achieved through 31P nuclear magnetic resonance (NMR) spectroscopy. We investigated how paramagnetic metals and quadrupolar nuclei cause severe line broadening, peak shifts, and decreased the signal to noise ratio. Results revealed that certain Po forms are readily bioavailable to Microcystis aeruginosa. Additionally, the potential heterotrophic use of the organic portion (e.g., glucose, glycerol) of these P compounds are indicated for the growth and persistence of Microcystis aeruginosa. We showed that the cultivation of rice (Oryza sativa L.) had been found to effectively reduce P from agrarian soil and water through plant uptake and, therefore, minimizing downstream eutrophication. Soil, water, sugarcane, and rice plants at two different stages were analyzed for twelve different elements. Finally, we examined how a “relic” agrarian ditch in Stormwater Treatment Area 1 East (STA-1E) can be used for the retention and sequestration of P and other nutrients. The STAs were established to capture P from agricultural and other sources before reaching the Everglades. Retained P is primarily stored in the wetland soils and sediments, generated through a collection of interrelated physical, chemical, and biological processes.

The goal of this experiment is to perfect the method of trimethylsilyl derivatization of fecal steroids Coprostan-3-one and Coprostanol using pyridine & N,O-bis-(trimethylsilyl)-trifluoroacetamide (BSTFA) containing 1% of Trimethylchlorosilane (TMCS). The extraction method for sediments involves Soxhlet extraction followed by saponification. The extraction of water samples will be done by XAD-2 resin or SPE with C18 cartridges and extracted with MeCl2. The primary instrument of this experiment was a Gas Chromatography- Mass spectroscopy (GC-MS). In addition, a Perkin-Elmer Autosystem GC coupled to a Perkin-Elmer TurboMass Gold mass spectrometer was used, with Helium as the carrier gas. Lastly, this experiment required a computer with Turbomass software version 5.4.2. to analyze samples after derivatization. The results of the GC-MS analysis showed that the methods of derivatization were correct.

Cyclopheophorbides absorb light at higher wavelengths (> 670 run) as compared
to their precursor pyropheophorbides ( ~ 666 run) and are strong antioxidants. Therefore
they could potentially be used as photosensitizers in photodynamic therapy, although this
study does not focus on the pharmacology aspect of this class of compounds.
The overall goal of this study was to hemisynthesize, purify and characterize
certain cyclopheophorbides from both chlorophyll a and b families. The known
hemisynthesis of 13^2,17^3-cyclopheophorbide a enol was repeated. A major success in the
purification process was achieved by utilizing polystyrene divinylbenzene (PS-DVB
a.k .a. PRP-1 TM) as the stationary phase in reversed phase flash chromatography. Altering
(TMS)2-NNa with (TMS)2-NLi was found to increase yields. 13^2,17^3 -mesocyclopheophorbide a enol was successfully hemisynthesized as a
novel compound.
Methyl-3-devinyl-3-[1-hexyloxy]ethyl pyropheophorbide a (HPPH-ME), was
prepared, purified and molecular characteri zation on the compound was performed. Hemisynthesis ofHPPH-CYCLO from HPPH-ME was attempted, but was
unsuccessful.
Zinc and copper pyropheophorbide a methyl esters were prepared with the intent
of forming of zinc and copper CYCLO. Hemisynthesis of corresponding metalloCYCLO
from both insertion of the metal inside the CYCLO core and cyclizations of
metal derivatives of pyropheophorbide a methyl ester were unsuccessful.
Chlorophyll b was successfully extracted from green algae Chiarella and purified
in mg lots (100%) utilizing RP-LPLC and with a binary solvent gradient program.
Pheophorbide b methyl ester and pyropheophorbide b methyl ester were made and
characterized. Hemisynthesis of CYCLO-b was unsuccessful likely due to the altered
reactivity of pyropheophorbide b (vs. -a) methyl ester. To reduce the reactivity, reduction
of formyl group of pyropheophorbide b methyl ester with NaBH4 was performed. Still,
formation of a CYCLO derivative was not achieved.
Chromatographic purification, mass and NMR characterization of CYCLO,
mesoCYCLO, HPPH-ME and all precursor compounds are reported. 2D NMR of most of
these compounds are reported here for the first time.

The molar and weight ratios of the photosynthetic pigments of ten algal species were
analyzed in an attempt to determine if knowledge of the light field could be used to
give better ratios for estimating the chlorophyll a contributed from each algal division
to total chlorophyll a or biomass. High performance liquid chromatography (HPLC)
is one of the tools used in pigment-based chemotaxonomy for estimating the biomass
of algal communities by determining the concentrations of the various chlorophylls
and carotenoids. Stable ratios of chlorophyll a: marker pigment are used as
multiplying factors for calculating the amount of chlorophyll a contributed from each
major algal group to total chlorophyll a. Stable chlorophyll a : marker pigment ratios
are not always easy to determine, so light field was investigated as a factor for
determining consistently reliable ratios. This data will serve to determine new
chlorophyll a: marker pigment ratios, as well as to verify or suggest changes to the
existing ratios that are currently being used by our research group. An unknown
pigment was isolated from Scytonema sp. grown in higher light fields and the
ecological significance of this pigment was assessed.

An analysis of the waters, microphytobenthos, and carbonate marl sediments of Florida Bay was performed using ion-paired RP-HPLC-PDA for chemotaxonomic characterization of past and present photoautotrophic, communities. Application of regression formulae was determined to be applicable for the waters, microphytobenthos, and surficial sediments (0--5 cm) of Florida Bay using chemotaxonomic principles. Loss of chemotaxonomically important pigments with depth prevented similar application in deeper strata (>5 cm), however, past oxic and anoxic trends could be determined. Sedimentary alteration of pigments are characterized by: rapid conversion of chlorophylls-alpha and bacteriochlorophylls-alpha to their respective pheophytins-alpha, creation of a 'carotenoid diol-cluster', equilibrium isomerization of beta-carotene (15-cis and trans), and rapid conversion of pyropheophorbide-alpha to cyclopheophorbide-alpha. An abundant presence of pyropheophorbide-alpha steryl/hopanoid esters and an unusual relationship between organic carbon and water content providing the sediments with polymeric characteristics were also found.

Carotenoid composition, tissue distribution, deposition in the
exoskeleton, and assimilation were studied in the blue crab, Callinectes
sapidus. Carotenoids identified were: alpha-carotene; beta-carotene;
lutein; 'carcinoxanthin'; isocryptoxanthin; echinenenone; canthaxanthin;
astaxanthin; and, astaxanthin esters. Tentative identification was made
for a-carotene, 8-carotene-monoepoxide, and phoenicoxanthin. The
occurrence of 'carcinoxanthin', in high concentration, in antennae and
eyestalks, is noted and discussed. Hepatopancreas yields mainly Bcarotene,
with more oxidized 'intermediates' and astaxanthin being
localized in the hypodermis. Exoskeletal carotenoids, both free and
conjugated to protein, were shown to be bound to chitin. Exoskeletal
carotenoprotein was shown to contain free astaxanthin as the only
carotenoid present. External coloration was analyzed and the underlying
pigments identified. Starved crabs with carotenoid-depleted
hepatopancreas were shown to assimilate beta-carotene, but not astaxanthin,
from test diets. Possible metabolic pathways and functions of
carotenoids in Crustacea are discussed.

Seagrass meadows in Florida Bay have rapidly declined due to synergistic stresses. The microalgal communities present on the leaves of Thalssia testudinum were studied in the Snake Bight and Whipray Basin areas of Florida Bay. These areas have been the sites of recurrent phytoplankton blooms and this study was aimed at exploring similar effects within the microalgal epiphytic communities. Epiphytometers, or surrogate seagrass, were used to provide a time zero (T0) point which is impossible in natural samples. Epiphyte samples were analyzed using HPLC/PDA which provided measurements of standing crop and community structure (>90% diatom). Epiphytometers were found to be excellent tool for monitoring epiphyte productivity on Thalassia. The monitoring of productivity, standing crop and community structure should allow insight into positive and negative effects of water supply changes.

The phytoplankton community of Lake Okeechobee, Florida, has been studied and algal divisions were identified. Chemotaxonomy is a process that assigns taxonomic divisions based on ratios of biomarker pigments to chlorophyll, as measured by high performance liquid chromatography (HPLC). Microscopic counts of taxonomic groups were compared to chemotaxonomic groups for lake samples for one year. Lab cultures of cyanobacteria grown at irradiance of 2 to 500 micromoles photons m-2 s-1 (muEinsteins) suggested that internal ratios of chlorophyll to both zeaxanthin and echinenone could be used to estimate abundance of cyanobacteria, as either alone missed certain populations. Lake water samples showed that both methods agreed that diatoms and cyanobacteria were the dominant groups, with moderate number of green algae and few dinoflagellates. HPLC evidence revealed cryptophytes more frequently than did microscopy. This suggested that cryptophytes may be more significant than has been previously reported.

Fresh and aged unispecific samples have been analyzed using IP-RPHPLC and PDA in order to reveal the chlorophylls and carotenoids alterations during senescence and death. Aging studies showed that cyanobacterial chlorophyll- a was destroyed faster than carotenoids in room oxic conditions. The reverse was found for the other eukaryotic species. Species with high chlorophyllase activity produced phytol free chlorophyll derivatives during death. The rate of chlorophyll-a destruction was; room oxic > room anoxic > cold anoxic. Pyropheophorbide-a was often the final product of type-I chlorophyll-a degradation. The conversion from fucoxanthin to fucoxanthinol was observed. Chlorophyll-c was found to be destroyed faster than chlorophyll-a. The quantitative relationship of certain "biomarker" pigments (e.g. fucoxanthin, zeaxanthin) to chlorophyll-a was found not to change significantly during the first 1--2 months senescence-death scenarios. This aids the field of chemotaxonomy in that valid estimations may still be made when phytoplankton populations contain senescent individuals.