The Complete Plastid Genome Sequence of Iris gatesii (Section Oncocyclus), a Bearded Species from Southeastern Turkey

Iris gatesii is a rare bearded species in subgenus Iris section Oncocyclus that occurs in steppe communities of southeastern Turkey. This species is not commonly cultivated, but related species in section Iris are economically important horticultural plants. The complete plastid genome is reported for I. gatesii based on data generated using the Illumina HiSeq platform and is compared to genomes of 16 species selected from across the monocotyledons. This Iris genome is the only known plastid genome available for order Asparagales that is not from Orchidaceae. The I. gatesii plastid genome, unlike orchid genomes, has little gene loss and rearrangement and is likely to be similar to other genomes from Asparagales. The plastid genome of I. gatesii demonstrates expansion of the inverted repeat, loss of 95% of the rps19–rpl22 intergenic spacer, the presence of introns in several protein-coding regions, and alternate start codons. Potentially variable regions are identified for further study

A Portrayal of the Work Life of Tenured African-american Female Faculty Working Within Historically White, Public Institutions of Higher Education in Virginia

The purpose of this study was to portray the experiences of African-American tenured female faculty employed within Historically White, public institutions of higher education in Virginia. This study is a portrait of the career paths, teaching experiences, institutional experiences, community and personal activities, work life, and the future of African-Americans. The study focused on personal experiences and provided a grounded recording for other African-American female faculty members employed within comparable institutions of higher education. The interviews also addressed educational preparation, mentoring, expectations, frustrations, difficulties, cultural and collegial experiences. Participants\u27 audio taped responses were transcribed. Similarities that evolved from the discussions were identified. Repeat conversations reflected concerns about the lack of role models, community, activities, isolation, mentoring, and access to professional development opportunities. These women were experiencing some of the same career paths, teaching experiences, institutional experiences, community and personal activities, and work life environments. The findings portrayed women that were very competent. The seven women interviewed had distinctive work ethics and, in spite of overloads in departmental responsibilities, at least six of them had completed some scholarly activities. These scholarly activities included funded grants, books, and community reform projects. These African-American women faculty members are still struggling to enter into the academic mainstream. They are currently working in different and uncertain environments. Being African-American and female places the women in this study in a subordinate role

Patterns in Evolution in Characters That Define Iris Subgenera and Sections

Subgeneric groups have been circumscribed in Iris based on a small number of morphological characters. Recent DNA sequence data has indicated that several of the subgenera, sections, and series that have previously been delineated are paraphyletic or polyphyletic. The evolution of characters that have traditionally been used to distinguish sub generic and sectional groups within Iris was investigated by mapping these characters on a phylogenetic tree based on matK sequence data. Results indicate that rhizomes are pleisomorphic for the genus and that three bulb types have arisen independently. My analysis shows that sepal beards, sepal crests, and seed arils show extensive homoplasy. Most of the homoplasy seen is associated with the circumscription of polyphyletic subgeneric groups such as the beardless subgenus Limniris. Some additional homoplasy is due to diversity within supported clades or the historical use of a single character in circumscribing more than one subgeneric group

Morphodynamics in Mid-Atlantic and New England saltmarshes: ecophysical processes and implications with sea-level rise

Thesis (Ph.D.)--Boston UniversityThis dissertation reports on the physical, biological, and biogeochemical processes in saltmarshes of Santee Delta, South Carolina, and Boston Harbor and Plum Island Estuary in Massachusetts to evaluate and quantify their dynamic response to sealevel rise. This includes comprehensive ecophysical analyses along the continuum of low to high marsh settings (South Carolina and Massachusetts, respectively), in addition to presenting information on historical saltmarsh evolution, recent anthropogenic alteration, and future sustainability. In the Santee Delta, South Carolina, relative sea-level rise is resulting in rapid creek extension on low marsh platforms of Spartina alterniflora. Measurements of redox potential, pH, belowground biomass, and soil strength reveal that crab colonization and bioturbation from the crab Sesarma reticulatum facilitate creek extension by altering the geotechnical and geochemical properties of the soil. Oxidized conditions in the upper 10-15 cm of the marsh induced by burrowing causes enhanced degradation of belowground biomass, which reduces the structural integrity of the soil and lowers elevation. This process ultimately increases the erosion potential of the sediment in creek head areas. In Plum Island Estuary, Massachusetts, creek extension is similarly occurring into localized depressions on high marsh platforms dominated by Spartina patens. Coring and stratigraphic analyses, elevation and vegetation surveys, and accretion rates on marsh platforms and in re-vegetating pools suggest the marshes are in dynamic equilibrium with sea-level rise. Degradation of organic matter, loss in elevation and pool formation is counterbalanced by creek incision, drainage, rapid revegetation, and regain in elevation. These marshes appear to be stable with respect to sea-level rise, and the recent increase in pool formation is linked to changes in drainage density. Finally, saltmarsh evolution throughout the Holocene is investigated in Boston Harbor. Cores, stratigraphic analysis and radiocarbon dating indicate that the marshes on Thompson and Peddocks Islands developed ~2-4 thousand years ago when rates of sea level rise decelerated after glacial melting. A reduction in sediment supply from drumlin bluff stabilization and anthropogenic diking has greatly impacted these marshes in the past century, evidenced by transition from high to low marsh vegetation. Their sustainability with accelerating rates of sea-level rise is questionable

Patterns in Evolution in Characters That Define Iris Subgenera and Sections

Subgeneric groups have been circumscribed in Iris based on a small number of morphological characters. Recent DNA sequence data has indicated that several of the subgenera, sections, and series that have previously been delineated are paraphyletic or polyphyletic. The evolution of characters that have traditionally been used to distinguish sub generic and sectional groups within Iris was investigated by mapping these characters on a phylogenetic tree based on matK sequence data. Results indicate that rhizomes are pleisomorphic for the genus and that three bulb types have arisen independently. My analysis shows that sepal beards, sepal crests, and seed arils show extensive homoplasy. Most of the homoplasy seen is associated with the circumscription of polyphyletic subgeneric groups such as the beardless subgenus Limniris. Some additional homoplasy is due to diversity within supported clades or the historical use of a single character in circumscribing more than one subgeneric group

Epiparasitism in Phoradendron durangense and P. falcatum (Viscaceae)

Phoradendron, the largest mistletoe genus in the New World, extends from temperate North America to temperate South America. Most species are parasitic on terrestrial hosts, but a few occur only, or primarily, on other species of Phoradendron. We examined relationships among two obligate epiparasites, P. durangense and P. falcatum, and their parasitic hosts. Fruit and seed of both epiparasites were small compared to those of their parasitic hosts. Seed of epiparasites was established on parasitic-host stems, leaves, and inflorescences. Shoots developed from the plumular region or from buds on the holdfast or subjacent tissue. The developing endophytic system initially consisted of multiple separate strands that widened, merged, and often entirely displaced its parasitic host from the cambial cylinder. During establishment the epiparasite invaded the cortex, vascular cylinder, and pith of its parasitic host and spread aggressively within host tissues, extending between and into individual host parenchyma cells, eventually isolating host cells or cell groups. The parasitic host showed little visual response to the epiparasite. Endophytic system growth of the epiparasite within its parasitic host was compared to that of a parasitic Phoradendron within its terrestrial host. The results indicate growth dynamics similar to those of parasitic species on terrestrial hosts. We conclude that the epiparasite/parasitic-host union should not be regarded as a graft union. The harmonious appearance of the union is a result of the growth of the epiparasite replacing entirely tissues of its parasitic host, with little or no hypertrophy of parasitic-host branches

Seasonal Variability of Forces Controlling Sedimentation in the Sundarbans National Forest, Bangladesh

Southwest Bangladesh, located on the Ganges-Brahmaputra-Meghna delta, is experiencing the impacts of sea level rise (SLR) due to processes at both the local and global scale. In particular, regional alterations of the hydrodynamic network, due to embankment construction, have drastically altered effective SLR, placing millions of inhabitants at risk of prolonged inundation, and threatening the world\u27s largest continuous mangrove stand, the Sundarbans National Forest (SNF). In order to effectively employ landscape recovery solutions, an understanding of local sediment transport and deposition is critical. This field-based study investigates the sediment dynamics between the mangrove platform and tidal channels of the SNF using data from a variety of instruments and sediment samples collected within a forested sub-basin (similar to 20 km(2)) fed by a major tidal channel. We observe profound seasonal variability within the sub-basin, with the wet season exhibiting a deeper and longer inundation of the mangrove platform and greater suspended sediment concentrations (SSC). Further, there exists a trend of decreasing SSC and median grain size from the perimeter of the SNF to the interior, and decreasing SSC from the tidal channel to the platform at both locations. We project seasonal platform sedimentation rates ranging from 0.17 +/- 0.16 cm in the dry season to 1.8 +/- 0.35 cm in the wet season. Importantly, the annual deposition rate measured at either location is sufficiently rapid to keep pace with observed rates of effective SLR published in other studies (similar to 1.0-1.7 cm/year). Based on our results, it appears that many controls on sedimentation are both covariant and of similar importance to land aggradation in the SNF. While inundation depth and frequency will likely increase under future SLR scenarios, sediment supply is threatened by India\u27s proposed River Linking Project, which could decrease the sediment loads of the Ganges and Brahmaputra Rivers by as much as 75 and 25%, respectively. These rivers provide the sediment for the entire delta, and we predict that with decreasing SSC, some regions-particularly interior sediment-depleted regions-may begin to deteriorate and become submerged, including within the SNF

Sinker Structure of Phoradendron californicum (Viscaceae) Confounds its Presumed Close Relationship to Other Acataphyllous Species

Phoradendron is the largest genus of New World mistletoes, with about 250 species in two subgenera, Boreales and Aequatoriales, corresponding, respectively, to northern acataphyllous and southern cataphyllous groups. The typically acataphyllous P. californicum of western North America is controversial because recent phylogenetic work has nested it in the southern cataphyllous clade. Seedling establishment, stem anatomy, and endophytic system structure of this species were studied. Seedling haustorial holdfasts have gland cavities, structures considered absent in the Viscaceae clade of Santalales. The stem epidermis has a thick cuticle, deeply sunken stomata, and branched multicellular trichomes. The stem has an outer cortex of palisade chlorenchyma and an inner cortex of large isodiametric parenchyma cells. The boundary area between the outer and inner cortex contains druses and an unusual ring of small xylic bundles lacking protoxylem fibers and phloem. Sinkers are of two types: uniseriate, with only parenchyma that often has thick-walled transfer cells at its interface with vessels of the host; and multiseriate, with parenchyma and vessel elements that often are in direct contact and share simple perforation plates with vessels of the host. Sinker morphology is also dimorphic in the cataphyllous P. fragile but only unimorphic (multiseriate) in the acataphyllous P. juniperinum and P. serotinum. The dimorphic sinker system of P. californicum may be functionally partitioned, whereas these functions are combined in the unimorphic sinkers of other acataphyllous species. Differences in sinker morphology may reflect evolutionary trends in Phoradendron. This study also supports the hypothesis that P. californicum is more closely aligned with the mainly tropical cataphyllous species of the genus

Computer Analysis of Spectrum Anomaly in 32-GHz Traveling-Wave Tube for Cassini Mission

Computer modeling of the 32-GHz traveling-wave tube (TWT) for the Cassini Mission was conducted to explain the anomaly observed in the spectrum analysis of one of the flight-model tubes. The analysis indicated that the effect, manifested as a weak signal in the neighborhood of 35 GHz, was an intermodulation product of the 32-GHz drive signal with a 66.9-GHz oscillation induced by coupling to the second harmonic'signal. The oscillation occurred only at low- radiofrequency (RF) drive power levels that are not expected during the Cassini Mission. The conclusion was that the anomaly was caused by a generic defect inadvertently incorporated in the geometric design of the slow-wave circuit and that it would not change as the TWT aged. The most probable effect of aging on tube performance would be a reduction in the electron beam current. The computer modeling indicated that although not likely to occur within the mission lifetime, a reduction in beam current would reduce or eliminate the anomaly but would do so at the cost of reduced RF output power

Surface Elevation and Sedimentation Dynamics in the Ganges-Brahmaputra Tidal Delta Plain, Bangladesh: Evidence for Mangrove Adaptation to Human-Induced Tidal Amplification

In the Ganges-Brahmaputra (G-B) delta, periodic flooding of the land surface during the tidal cycle coupled with enormous sediment delivery during the monsoon promotes sediment accretion and surface elevation gain through time. However, over the past several decades, widespread embankment (“polder”) construction in the GB tidal delta plain has led to numerous environmental disturbances, including channel siltation and tide range amplification. While previous research indicates that rates of sediment accretion are relatively high in the G-B tidal delta plain, it remains unclear if and how surface elevation is maintaining pace with relative sea-level rise (RSLR) in this region. In this study, we utilize an array of surface elevation tables, sediment traps, and groundwater piezometers to provide longitudinal trends of sedimentation and elevation dynamics with respect to local platform elevation and associated hydroperiod. Two hydro-geomorphic settings of the Sundarbans mangrove forest are compared: higher elevation stream-bank and lower elevation interior. Seasonal measurements over a time span of 5 years reveal that elevation gain is occurring in all settings, with the highest rates observed at elevated stream-bank zones. Elevation gain occurs primarily in response to sediment accretion, with possible minor contributions from pore-water storage and swelling of clay minerals during the monsoon season (i.e., belowground biomass and organic contribution is minimal). As a result, elevation loss and shallow subsidence in the G-B delta is unlikely to be caused by compaction of organic-rich soils, but rather appears to be controlled by seasonal lowering of the groundwater table and compaction of clay minerals. Rates of surface elevation gain in the Sundarbans greatly exceed rates of RSLR and more closely follow rates of RSLR augmented from tide range amplification, indicating that this landscape is adapting to human-induced environmental change. The proceedings of this study underscore the adaptability of the natural G-B tidal delta plain to local environmental disturbances, with the caveat that these defenses may be lost to future upstream reductions in sediment supply