Contribution of lipophilic secondary metabolites to the toxicity of strains of freshwater cyanobacterial harmful algal blooms, identified using the zebrafish (Danio rerio) embryo as a model for vertebrate development

Cyanobacteria ("blue-green algae") are known to produce a diverse repertoire of biologically active secondary metabolites. When associated with so-called "harmful algal blooms", particularly in freshwater systems, a number of these metabolites have been associated—as "toxins", or commonly "cyanotoxins"—with human and animal health concerns. In addition to the known water-soluble toxins from these genera (i.e. microcystins, cylindrospermopsin, and saxitoxins), our studies have shown that there are metabolites within the lipophilic extracts of these strains that inhibit vertebrate development in zebrafish embryos. Following these studies, the zebrafish embryo model was implemented in the bioassay-guided purification of four isolates of cyanobacterial harmful algal blooms, namely Aphanizomenon, two isolates of Cylindrospermopsis, and Microcystis, in order to identify and chemically characterize the bioactive lipophilic metabolites in these isolates. ^ We have recently isolated a group of polymethoxy-1-alkenes (PMAs), as potential toxins, based on the bioactivity observed in the zebrafish embryos. Although PMAs have been previously isolated from diverse cyanobacteria, they have not previously been associated with relevant toxicity. These compounds seem to be widespread across the different genera of cyanobacteria, and, according to our studies, suggested to be derived from the polyketide biosynthetic pathway which is a common synthetic route for cyanobacterial and other algal toxins. Thus, it can be argued that these metabolites are perhaps important contributors to the toxicity of cyanobacterial blooms. In addition to the PMAs, a set of bioactive glycosidic carotenoids were also isolated because of their inhibition of zebrafish embryonic development. These pigmented organic molecules are found in many photosynthetic organisms, including cyanobacteria, and they have been largely associated with the prevention of photooxidative damage. This is the first indication of these compounds as toxic metabolites and the hypothesized mode of action is via their biotransformation to retinoids, some of which are known to be teratogenic. Additional fractions within all four isolates have been shown to contain other uncharacterized lipophilic toxic metabolites. This apparent repertoire of lipophilic compounds may contribute to the toxicity of these cyanobacterial harmful algal blooms, which were previously attributed primarily to the presence of the known water-soluble toxins.^

Teachers' knowledge, awareness, and pedagogy of global education in secondary schools

In 1979, the Florida State Board of Education approved the teaching of global education in the state of Florida. The purpose of this study was to examine the factors that contributed to teachers' global knowledge, global mindedness, and pedagogy in global education. The Hanvey model of teaching from a global perspective was the theoretical framework for the study. ^ A total of 90 secondary teachers from Miami-Dade County Public Schools were randomly selected and placed in three groups: Globally Oriented Social Studies Program (GOSSE), Non-Globally Oriented Social Studies Program (non-GOSSE), and Teachers Who Teach Other Subjects (TWTOS). Seven teachers, two of whom team-taught a class, were selected for classroom observations and interviews. A mixed methods design that combined quantitative and qualitative data was used. ANOVA and Chi square techniques were used to determine whether the factors that contributed to teachers' global knowledge and global mindedness differ among groups. Classroom observations and interviews were conducted to determine whether the instructional strategies differ among the seven selected teachers. ^ The findings of the study show that teachers who were trained in teaching from a global perspective differed in their global knowledge and used more appropriate instructional strategies than teachers who were not trained in teaching global perspectives. There was no significant difference in the combined global knowledge of the non-GOSSE and TWTOS groups when compared with the GOSSE group. There was no significant difference in the combined global knowledge of the GOSSE and non-GOSSE groups when compared with the TWTOS group. There was no significant difference among the teachers in their global mindedness. Observation and interview data indicate that current events, role-playing, simulations, open-ended discussion, debates, and projects were the predominant instructional strategies used by globally trained teachers. Cable networks, Internet, magazines, and newspapers were found to be the dominant tools for teaching global education. ^ This study concluded that teachers who were trained in globally oriented programs had more global knowledge than teachers who were not. It is recommended that teacher education programs should incorporate a global perspective in the preparation of social studies teachers, with particular attention to developing their global attitudes. ^

The relationship between educational placement, instructional practices, and achievement gains of Black students with specific learning disabilities in secondary urban school settings

Black students, in general, are underserved academically (Darling-Hammond, 2000; Townsend, 2002) and overrepresented in special education (Donovan & Cross, 2002). Black students with disabilities are further overrepresented in more restrictive educational environments (Skiba, Poloni-Staudinger, Gallini, Simmons & Feggins-Azziz, 2006). Although the National Longitudinal Transition Study 2 (NLTS2) revealed that the academic performance of students with learning disabilities is positively related to the percentage of courses taken in the general education setting (Newman, 2006), the research specifically on placement of Black students with disabilities, particularly at the secondary level, as it relates to academic achievement is lacking. While previous studies have sought to determine which placement is better for students with disabilities, no study was found that specifically examined the impact of placement specific to Black students with specific learning disabilities (SLD) in urban settings (Fore, III, Hagan-Burke, Burke, Boon & Smith, 2008; Rea, McLaughlin & Walther-Thomas, 2002). This study examined educational placement, instructional best practices, and achievement gains of Black students with SLD in urban secondary settings using an ex post facto research design. Achievement, placement, and demographic data were collected and analyzed on approximately 314 Black eighth grade students with SLD. The Teacher Instructional Practices Survey was developed and used to collect and analyze data from the teachers of 78 of these students as it relates to instructional best practices. Results indicate no significant difference in reading but a significant difference in math gains of students served in inclusive settings as compared to resource settings with a small effect size. Also, no significant relationship was found between achievement gains and the reported use of instructional best practices. However, there was a relationship between educational placement and the use of instructional best practices. The results implied that there is a need for training with both general and special education teachers on instructional best practices for SWD and that there should be certain IEP team considerations when making placement decisions for this population of students with disabilities. It is recommended that future research in this area include classroom observations and factors other than test scores to measure growth in achievement.

Teachers’ Knowledge, Awareness and Pedagogy of Global Education in Secondary Schools

For the last fifty years, social studies teachers have been prepared to teach from a global perspective, but since September 11, 2001 have faced a difficult challenge teaching from a global perspective. This study examines ninety secondary school teachers’ global knowledge and their disposition toward teaching from a global perspective.

Origin of salinity variations in Florida Bay

This note presents a method of distinguishing the source of freshwater that causes reductions in salinity in the coastal environment of South Florida. This technique, which uses the 18O and D of the water, allows for differentiation of the freshwater derived from precipitation as opposed to runoff, because surface waters in the Everglades have been highly evaporated and therefore have elevated 18O and dD values relative to precipitation. A time series of monthly 18O and D values of surface waters, collected from stations in Florida Bay between 1993 and 1999, has shown that, during this time, the major source of freshwaters causing depressions in the salinity in the western portion of Florida Bay was derived from precipitation rather than from the runoff of water from the Everglades. In the eastern portion of Florida Bay, close to the boundary between peninsular Florida and the Bay, the proportion of freshwater derived from precipitation drops steadily, reaching <10%. This method not only allows differentiation between the sources of freshwater but can, in a temporal sense, ascertain the effectiveness of water management practices on the salinity of the estuarine ecosystems of South Florida.

Teachers' knowledge, awareness, and pedagogy of global education in secondary schools

Professor Mohammed K. Farouk, Major Professor In 1979, the Florida State Board of Education approved the teaching of global education in the state of Florida. The purpose of this study was to examine the factors that contributed to teachers' global knowledge, global mindedness, and pedagogy in global education. The Hanvey model of teaching from a global perspective was the theoretical framework for the study. A total of 90 secondary teachers from Miami-Dade County Public Schools were randomly selected and placed in three groups: Globally Oriented Social Studies Program (GOSSE), Non-Globally Oriented Social Studies Program (non-GOSSE), and Teachers Who Teach Other Subjects (TWTOS). Seven teachers, two of whom team-taught a class, were selected for classroom observations and interviews. A mixed methods design that combined quantitative and qualitative data was used. ANOVA and Chi square techniques were used to determine whether the factors that contributed to teachers' global knowledge and global mindedness differ among groups. Classroom observations and interviews were conducted to determine whether the instructional strategies differ among the seven selected teachers. The findings of the study show that teachers who were trained in teaching from a global perspective differed in their global knowledge and used more appropriate instructional strategies than teachers who were not trained in teaching global perspectives. There was no significant difference in the combined global knowledge of the non-GOSSE and TWTOS groups when compared with the GOSSE group. There was no significant difference in the combined global knowledge of the GOSSE and non- GOSSE groups when compared with the TWTOS group. There was no significant difference among the teachers in their global mindedness. Observation and interview data indicate that current events, role-playing, simulations, open-ended discussion, debates, and projects were the predominant instructional strategies used by globally trained teachers. Cable networks, Internet, magazines, and newspapers were found to be the dominant tools for teaching global education. This study concluded that teachers who were trained in globally oriented programs had more global knowledge than teachers who were not. It is recommended that teacher education programs should incorporate a global perspective in the preparation of social studies teachers, with particular attention to developing their global attitudes.

Present-day Pattern Variations in the Central and Eastern Pacific El Nino

El Niño and the Southern Oscillation (ENSO) is a cycle that is initiated in the equatorial Pacific Ocean and is recognized on interannual timescales by oscillating patterns in tropical Pacific sea surface temperatures (SST) and atmospheric circulations. Using correlation and regression analysis of datasets that include SST’s and other interdependent variables including precipitation, surface winds, sea level pressure, this research seeks to quantify recent changes in ENSO behavior. Specifically, the amplitude, frequency of occurrence, and spatial characteristics (i.e. events with maximum amplitude in the Central Pacific versus the Eastern Pacific) are investigated. The research is based on the question; “Are the statistics of ENSO changing due to increasing greenhouse gas concentrations?” Our hypothesis is that the present-day changes in amplitude, frequency, and spatial characteristics of ENSO are determined by the natural variability of the ocean-atmosphere climate system, not the observed changes in the radiative forcing due to change in the concentrations of greenhouse gases. Statistical analysis, including correlation and regression analysis, is performed on observational ocean and atmospheric datasets available from the National Oceanographic and Atmospheric Administration (NOAA), National Center for Atmospheric Research (NCAR) and coupled model simulations from the Coupled Model Inter-comparison Project (phase 5, CMIP5). Datasets are analyzed with a particular focus on ENSO over the last thirty years. Understanding the observed changes in the ENSO phenomenon over recent decades has a worldwide significance. ENSO is the largest climate signal on timescales of 2 - 7 years and affects billions of people via atmospheric teleconnections that originate in the tropical Pacific. These teleconnections explain why changes in ENSO can lead to climate variations in areas including North and South America, Asia, and Australia. For the United States, El Niño events are linked to decreased number of hurricanes in the Atlantic basin, reduction in precipitation in the Pacific Northwest, and increased precipitation throughout the southern United Stated during winter months. Understanding variability in the amplitude, frequency, and spatial characteristics of ENSO is crucial for decision makers who must adapt where regional ecology and agriculture are affected by ENSO.

Present-day Pattern Variations in the Central and Eastern Pacific El Nino

El Niño and the Southern Oscillation (ENSO) is a cycle that is initiated in the equatorial Pacific Ocean and is recognized on interannual timescales by oscillating patterns in tropical Pacific sea surface temperatures (SST) and atmospheric circulations. Using correlation and regression analysis of datasets that include SST’s and other interdependent variables including precipitation, surface winds, sea level pressure, this research seeks to quantify recent changes in ENSO behavior. Specifically, the amplitude, frequency of occurrence, and spatial characteristics (i.e. events with maximum amplitude in the Central Pacific versus the Eastern Pacific) are investigated. The research is based on the question; “Are the statistics of ENSO changing due to increasing greenhouse gas concentrations?” Our hypothesis is that the present-day changes in amplitude, frequency, and spatial characteristics of ENSO are determined by the natural variability of the ocean-atmosphere climate system, not the observed changes in the radiative forcing due to change in the concentrations of greenhouse gases. Statistical analysis, including correlation and regression analysis, is performed on observational ocean and atmospheric datasets available from the National Oceanographic and Atmospheric Administration (NOAA), National Center for Atmospheric Research (NCAR) and coupled model simulations from the Coupled Model Inter-comparison Project (phase 5, CMIP5). Datasets are analyzed with a particular focus on ENSO over the last thirty years. Understanding the observed changes in the ENSO phenomenon over recent decades has a worldwide significance. ENSO is the largest climate signal on timescales of 2 - 7 years and affects billions of people via atmospheric teleconnections that originate in the tropical Pacific. These teleconnections explain why changes in ENSO can lead to climate variations in areas including North and South America, Asia, and Australia. For the United States, El Niño events are linked to decreased number of hurricanes in the Atlantic basin, reduction in precipitation in the Pacific Northwest, and increased precipitation throughout the southern United Stated during winter months. Understanding variability in the amplitude, frequency, and spatial characteristics of ENSO is crucial for decision makers who must adapt where regional ecology and agriculture are affected by ENSO.

A molecular basis for polyketide biosynthesis in marine dinoflagellates with emphasis on Karenia brevis

Polyketides derived from dinoflagellates are among the most complex and unique structures identified to date. The carbon framework of all polyketides is assembled by a polyketide synthase (PKS). No studies of the biosynthesis of dinoflagellate derived polyketides at the genomic level have been reported to date. Nine strains representing seven different species of dinoflagellates were screened for the presence of type I and type II polyketide synthases (PKS) by PCR and RT-PCR. Seven of the nine strains yielded products that were homologous with known and putative type I polyketide synthases. In each case, the presence of a PKS gene was correlated with the presence of bacteria in the cultures as identified by amplification of the bacterial 16S rRNA gene. However, residual phylogenetic signals, resistance to methylation sensitive restriction enzymes and the lack of hybridization to bacterial isolates support a dinoflagellate origin for most of these genes. ^ A more detailed analysis of Karenia brevis, a toxic marine dinoflagellate endemic to the Gulf of Mexico, also supports the hypothesis that dinoflagellates have polyketide synthase genes. Blooms of this harmful alga cause fish kills, marine mammal mortalities and neurotoxic shellfish poisonings. These harmful effects are attributed to a suite of polyketide secondary metabolites known as the brevetoxins. PKS encoding genes amplified from K. brevis culture were found to be similar to PKS genes from the closely related protist, Cryptosporidium parvum. This suggested that these genes originate from the dinoflagellate. However, K. brevis has not been grown axenically. The associated bacteria might be the source of the toxins or the PKS genes. This dissertation reports the localization of these PKS encoding genes by a combination of flow cytometry/PCR and fluorescence in situ hybridization (FISH). Two genes localized exclusively to K. brevis cells while a third localized to both K. brevis and associated bacteria. While these genes have not yet been linked to toxin production, the work describes the first definitive evidence of resident PKS genes in any dinoflagellate. ^

Depth-related variations of trace metal abundances in south Florida sediments

Variations in trace element abundances with depth in soils and sediments may be due to natural processes or reflect anthropogenic influences. The depth related variations of five major elements (Fe, Si, Al, Ca and Mg), seventeen trace elements (Mn, Cr, Ti, P, Ni, Ba, Sc, Sr, Sb, Zn, Pb, Cd, Co, V, Be, Cu and Y) and volatile loss patterns were examined for sediment cores from five sites in South Florida (Lake Okeechobee, SFWMD Water Conservation area 3B, F.I.U., the Everglades and Chekika State Recreation Area). Principal component analysis of the chemical data combined with microscopic examination of the soils reveal that depth-related variations can be explained by varying proportions of three natural soil constituents and one anthropogenic component. The results can be used as a geochemical baseline for human influence on South Florida soils.

Light-activated phytotoxic thiophenes in Flaveria linearis L.

Chromatographic analyses of crude leaf extracts of Flaveria linearis L. revealed the presence of four acetylenic monothiophenes. Three of these metabolites were purified and structurally characterized by UV, NMR, IR, and GC-MS. Germination, growth, and survival/mortality studies with and without UVA, the activating wavelengths of these metabolites, were conducted with the crude leaf extracts and the purified compounds (taken individually and combined) against selected crop species (lettuce, radish, and carrot). Results suggest that acetylenic metabolites are phytotoxic against lettuce, carrot, and radish, but with variability in response among species. These variations in sensitivity and the allelopathic potential of F. linearis is discussed.