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Multiple domains in MtENOD8 protein including the signal peptide target it to the symbiosome

Description: Article presenting evidence from GFP fusion experiments that the MtENOD8 protein contains at least three symbiosome targeting domains, including its N-terminal signal peptide (SP).
Date: May 2012
Creator: Meckfessel, Matthew H.; Blancaflor, Elison B.; Plunkett, Michael; Dong, Qunfeng & Dickstein, Rebecca
Partner: UNT College of Arts and Sciences


Description: An analysis of outstanding problems still presenting difficulty with respect to understanding the quantumconversion process in photosynthesis is presented. Considerations of how some of these difficulties may be overcome are included. The dynamic process of energy conversion is considered in terms of photon absorption, electronic energy transfer, trapping in long-lived excited states, primary oxidants and reductants, and the electron transport chain leading to products representing stored chemical potential. The physical structure of the apparatus accomplishing this energy conversion is sought in the framework of the concept of the photosynthetic unit. The nature of this unit--its size, composition, arrangement and orientation of components, internal electrical and polarizability properties, and assembly and aggregation in the chloroplast--and the problems related to its determination are essential considerations in the overall approach to the understanding of the mechanism of energy conversion. (auth)
Date: December 1, 1962
Creator: Sauer, K.
Partner: UNT Libraries Government Documents Department

BEST: Bilingual environmental science training: Kindergarten level

Description: This booklet is one of a series of bilingual guides to environmental-science learning activities for students to do at home. Lesson objectives, materials required, procedure, vocabulary, and subjects integrated into the lesson are described in English for each lesson. A bilingual glossary, alphabetized by English entries, with Spanish equivalents in both English and Spanish, follows the lesson descriptions, and is itself followed by a bibliography of English-language references. This booklet includes descriptions of six lessons covering the senses of touch and sight, the sense of smell, how to distinguish living and non-living things, cell structures, the skeletal system, and the significance of food groups. 8 figs.
Date: March 1, 1996
Partner: UNT Libraries Government Documents Department

1997 Gordon Research Conference on Plant Cell Walls. Final progress report

Description: The Gordon Research Conference (GRC) on Plant Cell Walls was held at Tilton School, Tilton, New Hampshire, July 18-22, 1997. The conference was well attended with 106 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both US and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. In addition to these formal interactions, free time was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.
Date: August 25, 1999
Creator: Staehelin, A.
Partner: UNT Libraries Government Documents Department

Workshop on stems and trunks in plant form and function. Final report

Description: This document is the final report on the workshop on stems and trunks in plant form and function relating to DOE grant DE-FG06-93ER20128 which took place at Oregon State University in February 1994. The resulting book is organized into four sections and a synthesis: roles of stem architecture in plant performance, roles of stems in transport and storage of water, roles of live stem cells in plant performance, and the roles of stems in preventing or reacting to response to plant injury. The synthesis stemmed from debated and discussion by the authors and a few dozen other workshop participants. The authors cover many stem functions, although the list is not exhaustive, and the focus is on terrestrial woody tree stems, primarily of temperate and boreal zones. More research on trunks, branches and twigs is important for a baseline understanding of plant biology. In the face of anticipated human-caused changes to most environments, we need not only have a baseline understanding of whole-plant biology, but also predictive capabilities for how plants will react to perturbations.
Date: March 1, 1995
Creator: Gartner, B.L.
Partner: UNT Libraries Government Documents Department

Regulation of cell division in higher plants. Final technical report

Description: Research in the latter part of the grant period was divided into two parts: (1) expansion of the macromolecular tool kit for studying plant cell division; (2) experiments in which the roles played by plant cell cycle regulators were to be cast in the light of the emerging yeast and animal cell paradigm for molecular control of the mitotic cycle. The first objectives were accomplished to a very satisfactory degree. With regard to the second part of the project, we were driven to change our objectives for two reasons. First, the families of cell cycle control genes that we cloned encoded such closely related members that the prospects for success at raising distinguishing antisera against each were sufficiently dubious as to be impractical. Epitope tagging is not feasible in Pisum sativum, our experimental system, as this species is not realistically transformable. Therefore, differentiating the roles of diverse cyclins and cyclin-dependent kinases was problematic. Secondly, our procedure for generating mitotically synchronized pea root meristems for biochemical studies was far too labor intensive for the proposed experiments. We therefore shifted our objectives to identifying connections between the conserved proteins of the cell cycle engine and factors that interface it with plant physiology and development. In this, we have obtained some very exciting results.
Date: February 29, 2000
Creator: Jacobs, Thomas W.
Partner: UNT Libraries Government Documents Department

2003 Plant Cell Walls Gordon Conference

Description: This conference will address recent progress in many aspects of cell wall biology. Molecular, genetic, and genomic approaches are yielding major advances in our understanding of the composition, synthesis, and architecture of plant cell walls and their dynamics during growth, and are identifying the genes that encode the machinery needed to make their biogenesis possible. This meeting will bring together international scientists from academia, industry and government labs to share the latest breakthroughs and perspectives on polysaccharide biosynthesis, wood formation, wall modification, expansion and interaction with other organisms, and genomic & evolutionary analyses of wall-related genes, as well as to discuss recent ''nanotechnological'' advances that take wall analysis to the level of a single cell.
Date: September 21, 2004
Creator: Cosgrove, Daniel J.
Partner: UNT Libraries Government Documents Department

The Cotton Kinesin-Like Calmodulin-Binding Protein Associates with Cortical Microtubles in cotton Fibers

Description: Microtubules in interphase plant cells form a cortical array, which is critical for plant cell morphogenesis. Genetic studies imply that the minus end-directed microtubule motor kinesin-like calmodulin-binding protein (KCBP) plays a role in trichome morphogenesis in Arabidopsis. However, it was not clear whether this motor interacted with interphase microtubules. In cotton (Gossypium hirsutum) fibers, cortical microtubules undergo dramatic reorganization during fiber development. In this study, cDNA clones of the cotton KCBP homolog GhKCBP were isolated from a cotton fiber-specific cDNA library. During cotton fiber development from 10 to 21 DPA, the GhKCBP protein level gradually decreases. By immunofluorescence, GhKCBP was detected as puncta along cortical microtubules in fiber cells of different developmental stages. Thus the results provide evidence that GhKCBP plays a role in interphase cell growth likely by interacting with cortical microtubules. In contrast to fibers, in dividing cells of cotton, GhKCBP localized to the nucleus, the microtubule preprophase band, mitotic spindle, and the phragmoplast. Therefore KCBP likely exerts multiple roles in cell division and cell growth in flowering plants.
Date: May 1, 2003
Creator: L., Preuss M.; Delmar, D.P. & Liu, Bo
Partner: UNT Libraries Government Documents Department

[Final report for DOE contract FG03-88ER13882]

Description: The female reproductive organ, the gynoecium, is the most complex structure that plants produce. The molecular mechanisms that coordinate its development are unknown, but can be dissected by molecular genetics. The ettin (ett) mutation provides a remarkable window for viewing gynoecium development. ett induced alterations result from misinterpretation of positional information along longitudinal and transverse gynoecial axes. Molecular cloning revealed the ETT encoded amino acid sequence is homologous to transcriptional factors involved in signaling by the plant hormone auxin. Early ETT gene expression marks the site of the future outgrowth of the gynoecium. The primary gene sequence and pattern of expression of ETT fits with a role in hormone mediated signaling for regional development in the female organ.
Date: April 30, 1999
Partner: UNT Libraries Government Documents Department

Microsporogenesis and Embryogenesis in Quercus

Description: Representative species from two subgenera in the genus Quercus were examined for floral structure and phenology, microsporogenesis, and embryogenesis. The species selected for investigation were: Quercus alba in the Lepidobalanus subgenera, and Quercus coccinea and Quercus ilicifolia from the Erythrobalanus group. Photographs of flowering and photomicrographs of microsporogensis and embryogenesis are used for illustration. The male flowers of the three species are borne on catkins which develop in the scale leaf axils of the current vegetative bud or in separate male buds. Meiosis occurred in the spring at the beginning of bud enlargement; division figures were regular in all the material observed. A haploid chromosome number of 12 was confirmed for the three species. Pollen was shed on May 10, 1962, from trees of Quercus coccinea and Quercus ilicifolia; and on May 26, 1962 from Quercus alba. The female flowers are located in the axils of the new leaves. Seed development requires one growing season in Quercus alba, but two growing seasons are required to mature seed of Quercus coccinea and Quercus ilicifolia. The chronology of embryo development was similar for Quercus coccinea and Quercus ilicifolia; embryo development of Quercus alba was about two weeks behind that of the other two species. Definition of ovule dominance within a seed occurred at the time of early embryo development. Failure of this physiological expression of dominance results in multiseeded acorns. No abnormal embryogenesis per se was observed in relation to multiple embryo development. (auth)
Date: January 1, 1962
Creator: Stairs, G. R.
Partner: UNT Libraries Government Documents Department

A High-Throughput Microenvironment for Single-Cell Operations

Description: This project was conducted as a feasibility study, in preparation for including this work in the forthcoming ''Instrumented Cell'' (IC) Strategic Initiative. The goal of the IC is to study individual cells; the goal of this feasibility study was to determine the best method for isolating large numbers of individual cells in a way that facilitates various types of environmental changes and intracellular measurements. We have the capability to do this with one cell, and sought to expand the number of cells that we could study simultaneously. Our specific goal for this feasibility study was to discover a way to isolate individual cells, and impale them on a nanopipette. This would enable samples to be introduced into and removed from a cell.
Date: January 7, 2003
Creator: Christian, A T; Buckley, P & Miles, R R
Partner: UNT Libraries Government Documents Department


Description: The reproductive integrity of single meristematic cells of Tradescantia occidentalis exposed to acute doses of x rays was investigated. The dose response curve was sigmoid and similar to that reported for a variety of mammaliand cell lines having a D/sub O/ of 149 r and and extrapolation number of 1.6. Detailed observations were also made of all forms of chromatid and chromosome aberrations induced after irradiating all stages of the mitotic cycle of these same meristematic cells. Attempts were then made to correlate these two sets of data and to equate loss of genetic information to loss of reproductive integrity. (auth)
Date: January 1, 1962
Creator: Davies, D.R.
Partner: UNT Libraries Government Documents Department

On the origin of microcraters on the surface of ion beam bombardedplant cell walls

Description: Ion bombardment of plant and bacterial cellular material has recently been used as a tool for the transfer of exogenous DNA macromolecules into the cell interior region. The precise mechanism that leads to the transfer of macromolecules through the cell envelope is not yet clear, however it has been observed that the ion bombardment is accompanied by the formation of ''microcraters'' on the cell wall, and it is possible that these features provide channels for the macromolecule transfer. Thus the nature and origin of the microcraters is of importance to understanding the DNA transfer phenomenon as well as being of fundamental interest. We report here on some scanning electron microscope observations we have made of onion skin cells that have been subjected to electron beam bombardment of sufficiently high power density to damage the cell wall. The damage seen is much less than and different from the microcraters formed subsequent to ion bombardment. We speculate that the microcraters may originate from the explosive release of gas generated in the biomaterial by ion bombardment.
Date: June 1, 2005
Creator: Salvadori, M.C.; Teixeira, F.S. & Brown, I.G.
Partner: UNT Libraries Government Documents Department

Mechanism of Excretion of a Bacterial Proteinase: Demonstration of Two Proteolytic Enzymes Produced by a Sarcina Strain (Coccus P)

Description: A Sarcina strain (Coccus P) produces two proteolytic enzymes. One is found only extracellularly, is far more prevalent, and is actively excreted during exponential growth. It is the enzyme responsible for the known strong proteolytic activity of the cultures of this strain. A second protease is, however, produced which remains associated with the intact cells but is released by the protoplasts. The two enzymes appear unrelated in their derivation. Calcium ions play an essential role in preventing autodigestion of the excreted enzyme. Bacterial proteins are found outside the cell boundary as a consequence either of passive processes such as leakage or lysis or of active excretion. Under conditions in which leakage and lysis do not occur, as during exponential growth, the cell boundary is a barrier causing a complete separation of the bulk of the intracellular proteins from the one or very few extracellular proteins, with no trace of either type being detectable on the wrong side of the boundary. Since in bacteria there is no evidence of protein being produced other than internally, the separation into intraand extracellular proteins should occur after peptide chain formation. The question arises as to whether the structure of the cell boundary or that of the excreted proteins themselves determines this separation. Coccus P, a Sarcina closely related to Micrococcus lysodeikticus (3), produces an extracellular proteinase during the exponential phase of growth so that the process appears to be active excretion. The organism grows exponentially in a defined synthetic medium (12) to relatively high cell density (10{sup 9} cells/ml); therefore the mechanism of excretion can be studied over an extended period of time without the difficulties of changing growth rates. Coagulation of reconstituted skim milk provides a simple and sensitive assay for enzyme activity (I 1). The extracellular proteinase has also been purified and ...
Date: June 29, 1970
Partner: UNT Libraries Government Documents Department


Description: The Sludge Treatment Project (STP) is responsible for the disposition of sludge contained in the six engineered containers and Settler tank within the 105-K West (KW) Basin. The STP is retrieving and transferring sludge from the Settler tank into engineered container SCS-CON-230. Then, the STP will retrieve and transfer sludge from the six engineered containers in the KW Basin directly into a Sludge Transport and Storage Containers (STSC) contained in a Sludge Transport System (STS) cask. The STSC/STS cask will be transported to T Plant for interim storage of the STSC. The STS cask will be loaded with an empty STSC and returned to the KW Basin for loading of additional sludge for transportation and interim storage at T Plant. CH2MHILL Plateau Remediation Company (CHPRC) contracted with Fauske & Associates, LLC (FAI) to perform thermal and gas generation analyses for interim storage of STP sludge in the Sludge Transport and Storage Container (STSCs) at T Plant. The sludge types considered are settler sludge and sludge originating from the floor of the KW Basin and stored in containers 210 and 220, which are bounding compositions. The conditions specified by CHPRC for analysis are provided in Section 5. The FAI report (FAI/10-83, Thermal and Gas Analyses for a Sludge Transport and Storage Container (STSC) at T Plant) (refer to Attachment 1) documents the analyses. The process considered was passive, interim storage of sludge in various cells at T Plant. The FATE{trademark} code is used for the calculation. The results are shown in terms of the peak sludge temperature and hydrogen concentrations in the STSC and the T Plant cell. In particular, the concerns addressed were the thermal stability of the sludge and the potential for flammable gas mixtures. This work was performed with preliminary design information and a preliminary software configuration.
Date: April 29, 2010
Partner: UNT Libraries Government Documents Department

Identification of a Xylogalacturonan Xylosyltransferase Involved in Pectin Biosynthesis in Arabidopsis

Description: Xylogalacturonan (XGA) is a class of pectic polysaccharide found in plant cell walls. The Arabidopsis thaliana locus At5g33290 encodes a predicted Type II membrane protein, and insertion mutants of the At5g33290 locus had decreased cell wall xylose. Immunological studies, enzymatic extraction of polysaccharides, monosaccharide linkage analysis, and oligosaccharide mass profiling were employed to identify the affected cell wall polymer. Pectic XGA was reduced to much lower levels in mutant than in wild-type leaves, indicating a role of At5g33290 in XGA biosynthesis. The mutated gene was designated xylogalacturonan deficient1 (xgd1). Transformation of the xgd1-1 mutant with the wild-type gene restored XGA to wild-type levels. XGD1 protein heterologously expressed in Nicotiana benthamiana catalyzed the transfer of xylose from UDP-xylose onto oligogalacturonides and endogenous acceptors. The products formed could be hydrolyzed with an XGA-specific hydrolase. These results confirm that the XGD1 protein is a XGA xylosyltransferase. The protein was shown by expression of a fluorescent fusion protein in N. benthamiana to be localized in the Golgi vesicles as expected for a glycosyltransferase involved in pectin biosynthesis.
Date: August 19, 2009
Creator: Pauly, Markus; Sorensen, Susanne Oxenboll; Harholt, Jesper; Geshi, Naomi; Sakuragi, Yumiko; Moller, Isabel et al.
Partner: UNT Libraries Government Documents Department

The Role of a Host Protein (TIP) in the Resistance Response of Arabidopsis to Turnip Crinkle Virus Infection.

Description: Our research on Turnip crinkle virus (TCV) has shown that the viral capsid protein (CP) is both a virulence factor as well as the elicitor of a hypersensitive resistance response (HR) to the virus in Arabidopsis. Initially, we identified a protein from Arabidopsis that specifically interacted with the viral CP using a yeast two-hybrid screen. This protein, designated TIP for TCV-Interacting Protein, is a member of the NAC family of plant transcription factors implicated in the regulation of development and senescence. When TCV CP was mutated to eliminate its ability to interact with TIP, the corresponding virus mutants broke the HR-mediated resistance conferred by the HRT resistance (R) gene in Arabidopsis ecotype Dijon (Di)-17. This result suggested that TIP is a component of the signal transduction pathway that leads to the genetically specified TCV resistance. We next confirmed that TIP and the viral CP interact in plant cells and that this interaction prevents nuclear localization of this transcription factor. We demonstrated that TCV CP suppresses post-transcriptional gene silencing (PTGS), a newly discovered RNA-mediated defense system in plants. Together these results suggest that the CP is a virulence factor that could well be functioning through its interaction with TIP. We have proposed a model involving the role of TIP and CP in triggering HR mediated plant defense that fits with the current thinking about how gene-for-gene resistance may function. A unique component of our system is the opportunity to link R-gene function with the newly discovered RNA silencing pathway that is not only a potent defense against viral pathogens, but also regulates early development in plants. In the current funding period we made several significant findings: First, we completed an array analysis comparing gene expression in Arabidopsis infected with TCV and a mutant virus unable to bind TIP. Second, we produced ...
Date: October 20, 2008
Creator: Morris, T. Jack
Partner: UNT Libraries Government Documents Department

Mechanisms of lignin biosynthesis during xylogenesis in Zinnia elegans. Final report, July 1, 1992--June 30, 1996

Description: This project initially focused on identifying and characterizing three components of the extracellular lignification reaction: peroxidases, hydrogen peroxide production, and oxygen dependent oxidases. Zinnia elegans was utilized for the model organism. Laccase activity was found to be more tightly correlated with lignification than peroxidase activity.
Date: May 1, 1997
Creator: Eriksson, K.E.L. & Dean, J.F.D.
Partner: UNT Libraries Government Documents Department