Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"pollen grains"”.
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Evolution and ecology of C4 grasses: insights from carbon isotope analysis of grass pollen grains
… I addressed this limitation by utilizing Single Pollen Isotope Ratio AnaLysis (SPIRAL), a technique that reliably distinguishes C4 from C3 grasses in the fossil record via δ13C values of individual pollen grains. Before applying the technique to fossil samples, I refined the original SPIRAL …
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Pollen study in Castanea dentata and C. mollissima
… the direction and distance of C. dentata pollen dispersal. The study of C. dentata pollen dispersal patterns was set up at an isolated orchard in Cleveland, Tennessee. Pollen collectors were placed at 13 locations in an array 15.2, 30.4, 46 and 61 meters north, northeast and east from the …
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Identifying floral hosts of cerambycid beetles using palynology
Pollen is an important food source for many insects including the adults of beetles whose larvae are important forest pests. I quantified the distribution of pollen-feeding in adults of several species of long-horned beetles (Coleoptera: Cerambycidae). Palynivory by cerambycid beetles is common in …
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Application of high-throughput methods to reconstruct the evolutionary history of amherstieae by using the fossil pollen record of Striatopollis catatumbus and extant geographical records of the tribe
… improve the taxonomic identification of fossil pollen. It also applies an ecological analysis to review how climate has played a role in the modern geographic distributions of tropical plants, especially the legume tribe Amherstieae. First, superresolution confocal microscopy was used to …
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Small mammal pollination in Protea Witzenbergiana
… Mammal droppings were collected, processed and pollen grains were counted. All small mammal species excepting one (Otomys irroratus) contained pollen grains in their faeces. Oendromus melanotis, Mus minutoides and Aethomys namaquensis were found to be the most important pollinators. The small …
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Integrating discrete stochastic models with single-cell and single-molecule experiments
… single cells. Much like Robert Brown looking at pollen grains in water, experimentalists have noticed that individual cells that are genetically identical behave seemingly randomly in the way they carry out their most basic functions. The field of stochastic single-cell biology has been focused …
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Palynological analysis from a bush karoo rat (Otomys unisulcatus) lodge near Prince Albert, South Africa
… research in this region. The preservation of pollen in middens in arid environments from different parts of the world has great potential for the reconstruction of past vegetation. A lodge of the bush karoo rat (Otomys unisulcatus) was excavated near Prince Albert, South Africa, and the high …
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Fungi associated with the pistillate flowers of white oak (Quercus alba L.) and their effect on pollen germination
… <u>Fusarium</u>. The effect of fungal spores on pollen germination was investigated. Suspensions of pollen grains and fungi spores were cultured in Van Tieghem cells. Pollen germination <u>in vitro</u> was significantly enhanced by <u>Cladosporium</u> and <u>Epicoccum</u>, but unaffected by …
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Cave pollen taphonomy in Kurdish Iraq
… aims to understand the mechanisms involved in pollen transport and deposition in cave environments and the influence of different factors on the composition of the pollen assemblage, with special reference to the problem of the Neanderthal ‘Flower burial’ at Shanidar Cave, Kurdish Iraq. Limited …
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Chromosome pairing and its relationship to fertility in cytotypes of prairie cordgrass (Spartina pectinata Link)
… may lead to inconsistent chromosome numbers in pollen grains, whereas normal meiosis I in the tetraploids is hypothesized to generate pollen with consistent chromosome numbers. To investigate this potential effect, pollen morphology and DNA content of pollen nuclei were analyzed in tetraploids …
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Pollen allergy in the Icelandic urban landscape
Since years the global number of pollen allergy sufferers keeps rising. A trend connected and influenced by several factors such as pollution, man-made monodominant planting communities and reduced biodiversity, mainly seen in the urban landscape. For city dwellers urban green spaces are essential …
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Paleolimnology of selected Precambrian Shield lakes /
… (1 cm) analyses of diatoms, Mallomonas scales, pollen grains and sedimentary phosphorus. Found and Jake Lake are adjacent to Highway 60, whereas Delano Lake has been undisturbed and was used as a control. Dramatic changes in the diatom and Mallomonas communities were recorded in the Found and …
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Novel applications of surface-modified sporopollenin exine capsules
The external shell (exine) of plant spores and pollen grains is composed of sporopollenin, which is an organic polymer renowned for its exceptional resistance to physical and chemical attack. The resilience of sporopollenin to high temperature, pressures, acidic and basic corrosion is proved by its …
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The influence of linear landscape features on pollinator behaviour
… poorly connected patches. Pollinator abundance, pollen grains per stigma and seed yield, were greater in highly connected patches compared with patches with fewer connecting hedgerows. The overall connectedness of a landscape may therefore be important to both pollinator movement and those plants …
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Paleoenvironmental reconstruction based on palynological and palynofacies analyses of the Aptian-Albian succession in the Sergipe Basin, northeastern Brazil
… Altogether 19 species of spores, 31 species of pollen grains, 20 species of dinocysts were identified. Moreover, one genus of Acritarcha and one genus of fresh-water algae were recorded. The sections are clearly dominated by the pollen group, in particular gymnosperms, which is by far the most …
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Paths Towards Shape Change: Elastic Instabilities and Spontaneous Deformations
… on the mammal brain or the folding of pollen grains. In the case of soft active materials, we show that the ballooning instability and phase separation can be triggered and amplified by the spontaneous deformation of LCEs; that a coiling instability can be induced in spontaneous …
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Imaging nanoscale pollen morphology with Superresolution Structured Illumination Microscopy
… diagnostic surface texture of individual pollen grains, is a special challenge for researchers. However, a combination of high-resolution imaging and computational analyses promises to unveil such nanoscale plant morphology for a whole spectrum of hypotheses, including those that address …
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Palynology, palynofacies and hydrocarbon potential of the Cretaceous rocks of northern Egypt
… of spores, gymnosperm<br/>and angiosperm pollen and dinoflagellate cysts. Three new palynostratigraphically<br/>defined age divisions are described for the lower part of the Abu Tunis 1x<br/>succession, and a more refined biostratigraphy is made for the upper part of the<br/>sequence. In …
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Multigene Metabolic Engineering Via The Chloroplast Genome
… except for the male sterile phenotype, lacking pollen. Scanning electron microscopy revealed a collapsed morphology of the pollen grains. Transgenic lines followed an accelerated anther developmental pattern, affecting their development and maturation, resulting in aberrant tissue patterns. …
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Some aspects of the seed development and seedling growth of rimu, Dacrydium cupressinum, Lamb
… Of the 1,500 ovules examined 21% contained no pollen grains, 47% 1 grain, 23% 2 grains and 9% between 3 and 5 grains. High levels of pollination (mean 1.5 pollen grains per ovule) were found in Whirinaki and Ashley Forests and low levels (mean less than one grain per ovule) in Tautuku and …
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