Lead (Pb) pollution is a serious environmental problem. Phytoremediation is emerging as a promising technology for removal of Pb and other heavy metals from soils and waterways. In this study, the phytoremediation potential of a popular landscape plant, in New Zealand, Cyathea medullaris (the black tree fern), was investigated. Pb uptake by the gametophytes and different parts (roots, shoots and leaves) of 3-month-old black tree fern plants in hydroponic experiments were studied using flame atomic absorption spectrometry. Morphological and ultrastructural changes in the Pb-treated materials were also investigated. Generally, the levels of Pb in the various black tree fern tissues increased with the external Pb concentration and exposure time. Transmission electron microscopy observation showed that the cell wall was the major subcellular site for Pb accumulation. Evidence obtained here suggests that the black tree fern gametophytes and the sporophyte can accumulate levels of Pb exceeding 1% of their dry weights. This resembles the capacity of a hyperaccumulating plant.

Lead (Pb) pollution is a serious environmental problem. Phytoremediation is emerging as a promising technology for removal of Pb and other heavy metals from soils and waterways. In this study, the phytoremediation potential of a popular landscape plant, in New Zealand, Cyathea medullaris (the black tree fern), was investigated. Pb uptake by the gametophytes and different parts (roots, shoots and leaves) of 3-month-old black tree fern plants in hydroponic experiments were studied using flame atomic absorption spectrometry. Morphological and ultrastructural changes in the Pb-treated materials were also investigated. Generally, the levels of Pb in the various black tree fern tissues increased with the external Pb concentration and exposure time. Transmission electron microscopy observation showed that the cell wall was the major subcellular site for Pb accumulation. Evidence obtained here suggests that the black tree fern gametophytes and the sporophyte can accumulate levels of Pb exceeding 1% of their dry weights. This resembles the capacity of a hyperaccumulating plant.

Thesis (M.S.)--Miami University, 2007. / Title from first page of PDF document. Includes bibliographical references (p. 38-43). Also available online via OhioLINK's ETD Center: http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1193256414.

Thesis (M.S.)--Miami University, Dept. of Botany, 2007. / Title from first page of PDF document. Includes bibliographical references (p. 38-43).

A dissertation submitted to the faculty of science university of the Witwatersrand, Johannesburg for the Degree of Master of Science Johannesburg 1992 / The gametophyte generation of the fern life cycle is initiated with the formation of spores. The spores of C. viridis (Fonsic) Swarts var. glaeca (Sim) schelp Anthony are trilete and have a cristate spore wall ornamentation. Under favourable conditions the spores of C. viridis var. glauca show polar germination [Abbreviated Abstract. Open document to view full version] / GR2017

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The mission statements of Utah State University and the Department of Biology, as well as the requirements of funding agencies like the National Science Foundation encourage an integration of teaching and research. I have attempted to achieve that in my dissertation work by using tools I originally created to support and inform my biological research projects to teach science content and inquiry to middle school and undergraduate students. Chapter 2 of this dissertation reports the results of surveys for Hymenophyllum wrightii, a fern with independent gametophyte populations in the Pacific Northwest, which improved our understanding of the range, distribution, and habitat requirements of this species that was previously thought to be rare. The result of these surveys led to the removal of the species from the Forest Service's Alaska Region Sensitive Species List and provided a first report of the species in the contiguous United States. A preliminary genetic data analyses of gametophyte populations found during the surveys sets the stage for future work to determine the relationships between the independent gametophyte populations and sporophytes growing in Haidi Gwaii, British Columbia and East Asia, which is important for understanding their evolutionary and conservation potential. Chapter 3 describes an attempt to explore the population genetics of another fern with independent gametophyte populations, Crepidomanes intricatum in the Appalachian mountains of Eastern North America. This species apparently exists only as gametophytes, which raises interesting questions about how and when it was established, and its conservation and evolutionary potential. This population genetics analysis was not able to be completed, but led to an analysis of potential sources of error in genotyping-by-sequencing datasets and to the development of a set of software tools for evaluating the quality of these datasets. To help better visualize the evolutionary processes at work in populations of ferns with independent gametophytes, I developed an interactive software tool to simulate populations of ferns in a virtual 3-dimensional space. Chapter 4 describes that tool, an educational activity using it to teach population genetics and science inquiry to undergraduates, and the results of a study demonstrating its effects on student content learning and confidence in their ability to perform inquiry. This tool and the activity built around it have been used in undergraduate genetic laboratories at Utah State University since 2011. The apparent benefits of this simulation tool led to a collaboration with educators and the development of another 3-dimensional simulation tool to teach eight grade students about the effects of the environment and human impacts on living organisms. Chapter 4 presents an educational activity using this tool that has been used as part of a larger National Science Foundation funded project to train teachers to use technology in the classroom. The simulations are publicly available and have been used by hundreds of students in two Utah school districts. Together, these projects demonstrate on way that research to expand knowledge can lead to tools to impart knowledge to students.

Gracilaria caudata J. Agardh is one of the naturally occurring species in Brazil that produce good quality agar. In Rio do Fogo (RN), Brazil, a green variant was discovered in a G. caudata population of predominantly red (wild phenotype) tetrasporophytes. Epiphytes gametophytes on tetrasporophytes have been observed for both strains. Considering the wild and green variant strains in laboratory control conditions, this study: (i) assessed the impacts of epiphyte gametophytes on tetrasporophytes by evaluating the growth rates, the pigment content, and the photosynthetic potential of the tetrasporophytes; (ii) evaluated the amount of time required for the differentiation of cystocarps in free-living gametophytes and epiphyte gametophytes on tetrasporophytes; (iii) evaluated the number of epiphyte gametophytes produced by tetrasporophyte; and (iv) analyzed anatomical aspects of the intersection between the tetrasporophytes and the tetraspores that germinated on the tetrasporophytes. Samples were cultivated for 12 weeks on laboratory conditions. Control samples had epiphyte gametophytes growing on them, while treatment samples had their epiphyte gametophytes removed weekly. Physiological analyses compared control and treatment samples, while anatomical analysis used the control samples only. Considering the tetrasporophyte growth rates before fertility (2nd week), wild strain showed higher values than green variant; however, after 12 weeks, no differences were found between strains or between samples without epiphyte gametophytes. The wild strain produced tetraspores more frequently than the green variant and showed deficiency in phycoerythrin and allophycocyanin. Green variant treatment samples had higher content of allophycocyanin, phycocyanin and phycoerythrin than the control samples. Chlorophyll a was higher in the wild strain, and treatment samples had lower values in comparison to control samples. Epiphyte gametophytes possibly promoted reduction in pigment content of the tetrasporophytes on both strains. Wild strain samples without epiphyte gametophytes had higher photosynthetic efficiency. Epiphyte gametophytes produced cystocarps one week before free-living gametophytes. The amount of epiphyte gametophytes on tetrasporophytes is not different between strains. Epiphyte gametophytes were visible one week before on the wild strain than in the green variant strain. It was found that tetraspores give rise to epiphyte gametophytes through two distinct germination methods: outside or inside the thallus of the tetrasporophyte. Germination outside the tetrasporophyte thallus was more common, produced visible holdfasts and promoted cortex thickening in the cortical region of the tetrasporophyte. Germination inside the tetrasporophyte thallus did not show evidences of holdfasts nor cortex thickening on the tetrasporophytes. Epiphyte gametophytes holdfasts had adjacent cells to the cortex of the tetrasporophytes when they germinate outside the thallus; however, when germination occurred inside the thallus, the connection interface was closer to the medulla of the tetrasporophyte. Epiphyte gametophytes might represent a new life strategy that promotes sexual variability in a population mostly composed of tetrasporophytes. For cultivation purposes, wild tetrasporophytes with epiphyte gametophytes yielded more mass than the variant tetrasporophytes, being the best option for production. However, the green variant without epiphyte gametophytes produced more phycobiliproteins, making it a better option to harvest those substances / Gracilaria caudata J. Agardh é uma das espécies encontradas na costa brasileira que produzem ágar de boa qualidade. Em Rio do Fogo (RN), Brasil, uma linhagem variante verde de G. caudata foi descoberta em uma população composta principalmente por indivíduos de coloração vermelha (fenótipo selvagem). Gametófitos epífitos em tetrasporófitos foram observados para as duas linhagens. Considerando-se as linhagens selvagem e verde em condições controladas de laboratório, este estudo analisou: (i) os impactos dos gametófitos epífitos nos tetrasporófitos por meio de taxas de crescimento, conteúdo pigmentar e potencial fotossintetizante dos tetrasporófitos; (ii) o tempo necessário para a diferenciação de cistocarpos em gametófitos de vida livre e gametófitos epífitos; (iii) o número de gametófitos epífitos produzidos por tetrasporófito; e (iv) aspectos anatômicos da interseção entre tetrasporófitos e gametófitos epífitos. O experimento teve duração de 12 semanas. Amostras controle foram mantidas com seus gametófitos epífitos durante o experimento, enquanto as amostras tratamento tiveram seus gametófitos epífitos removidos semanalmente. Análises fisiológicas compararam amostras controle e tratamento, enquanto que para os estudos anatômicos utilizou-se apenas as amostras controle. A linhagem selvagem apresentou maiores taxas de crescimento que a linhagem verde nas duas primeiras semanas do experimento, quando ainda não estavam férteis; entretanto, após as doze semanas de cultivo, não foram observadas diferenças entre as linhagens tetrasporofíticas. A linhagem vermelha produziu tetrásporos com mais frequência do que a linhagem verde e apresentou deficiência em ficoeritrina e aloficocianina. As amostras tratamento da linhagem verde apresentaram valores maiores de aloficocianina e ficoeritrina do que às do controle. A linhagem selvagem apresentou menores teores de ficoeritrina e aloficocianina quando comparada à linhagem verde. As amostras tratamento da linhagem verde apresentaram maiores valores de aloficocianina, ficocianina e ficoeritrina que as amostras controle da mesma linhagem. A quantidade de clorofila a foi maior na linhagem selvagem, e as amostras tratamento desta linhagem apresentaram valores maiores que às do controle. A presença de gametófitos epífitos promoveu a redução no conteúdo pigmentar nas duas linhagens. Amostras tratamento da linhagem selvagem apresentaram potencial fotossintetizante maior do que amostras controle. A quantidade de gametófitos epífitos não foi diferente entre as linhagens. Gametófitos epífitos produziram cistocarpos uma semana antes do que gametófitos de vida livre. A linhagem selvagem produziu gametófitos epífitas uma semana antes da linhagem verde. A germinação de tetrásporos em tetrasporófitos ocorreu de duas maneiras: antes e após a liberação de tetrásporos. A liberação de tetrásporos seguida da germinação sobre o tetrasporófito foi mais frequente, produziu apressórios e promoveu aumento do número de células no córtex do tetrasporófito. A germinação de tetrásporos dentro do talo do tetrasporófito não apresentou evidências de apressórios ou espessamento da região cortical do tetrasporófito. A porção basal de apressórios de gametófitos epífitos permaneceu adjacente ao córtex do tetrasporófito. Quando a germinação do tetrásporo ocorreu ainda dentro do talo, a interface de conexão das células foi mais próxima da medula do tetrasporófito. Gametófitos epífitos podem representar uma nova estratégia de vida para a espécie por possibilitar a variabilidade por reprodução sexual em uma população predominantemente composta por tetrasporófitos. Para um possível cultivo em larga escala, tetrasporófitos com gametófitos epífitos da linhagem selvagem seriam mais adequados por produzirem mais massa que os da variante verde. Entretanto, se o objetivo for a produção de ficobiliproteínas, a linhagem verde seria a mais indicadaphycoerythrin and allophycocyanin. Green variant treatment samples had higher content of allophycocyanin, phycocyanin and phycoerythrin than the control samples. Chlorophyll a was higher in the wild strain, and treatment samples had lower values in comparison to control samples. Epiphyte gametophytes possibly promoted reduction in pigment content of the tetrasporophytes on both strains. Wild strain samples without epiphyte gametophytes had higher photosynthetic efficiency. Epiphyte gametophytes produced cystocarps one week before free-living gametophytes. The amount of epiphyte gametophytes on tetrasporophytes is not different between strains. Epiphyte gametophytes were visible one week before on the wild strain than in the green variant strain. It was found that tetraspores give rise to epiphyte gametophytes through two distinct germination methods: outside or inside the thallus of the tetrasporophyte. Germination outside the tetrasporophyte thallus was more common, produced visible holdfasts and promoted cortex thickening in the cortical region of the tetrasporophyte. Germination inside the tetrasporophyte thallus did not show evidences of holdfasts nor cortex thickening on the tetrasporophytes. Epiphyte gametophytes holdfasts had adjacent cells to the cortex of the tetrasporophytes when they germinate outside the thallus; however, when germination occurred inside the thallus, the connection interface was closer to the medulla of the tetrasporophyte. Epiphyte gametophytes might represent a new life strategy that promotes sexual variability in a population mostly composed of tetrasporophytes. For cultivation purposes, wild tetrasporophytes with epiphyte gametophytes yielded more mass than the variant tetrasporophytes, being the best option for production. However, the green variant without epiphyte gametophytes produced more phycobiliproteins, making it a better option to harvest those substances