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Articles 1681 - 1710 of 1739

Full-Text Articles in Life Sciences

Simple, Compact Source For Low-Temperature Air Plasmas, D. P. Sheehan, J. Lawson, M. Sosa, Richard A. Long Jul 2002

Simple, Compact Source For Low-Temperature Air Plasmas, D. P. Sheehan, J. Lawson, M. Sosa, Richard A. Long

Faculty Publications

A simple, compact source of low-temperature, spatially and temporally uniform air plasma using a Telsa induction coil driver is described. The low-power ionization discharge plasma is localized (2 cm X 0.5 cm X 0.1 cm) and essentially free of arc channels. A Teflon coated rolling cylindrical electrode and dielectric coated ground plate are essential to the source’s operation and allow flat test samples to be readily exposed to the plasma. The plasma is a copious source of ozone and nitrogen oxides. Its effects on various microbes are discussed.

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Seasonal Niche Strategy Of The Bloom-Forming Dinoflagellate Heterocapsa Triquetra, R. W. Litaker, P. A. Tester, C. S. Duke, B. E. Kenney, James L. Pinckney, J. Ramus May 2002

Seasonal Niche Strategy Of The Bloom-Forming Dinoflagellate Heterocapsa Triquetra, R. W. Litaker, P. A. Tester, C. S. Duke, B. E. Kenney, James L. Pinckney, J. Ramus

Faculty Publications

Heterocapsa triquetra is one of the most common bloom-forming dinoflagellates found in estuaries and near shore regions around the world. This work examined the environmental factors associated with 3 separate wintertime H. triquetra blooms in the shallow tidally mixed Newport River estuary, North Carolina, USA. During 2 of the blooms in 1982 and 1983, the estuary was sampled from a fixed, single location every hour for 14 d. During the third study, the estuary was sampled at 9 fixed locations over its entire length each week from late December 1997 through March 1998. This time period included the formation and …

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Estimating The Spatial Extent Of Bottom-Water Hypoxia And Habitat Degradation In A Shallow Estuary, Christopher P. Buzzelli, Richard A. Luettich Jr., Sean P. Powers, Charles H. Peterson, Jesse E. Mcninch, James L. Pinckney, Hans W. Paerl Apr 2002

Estimating The Spatial Extent Of Bottom-Water Hypoxia And Habitat Degradation In A Shallow Estuary, Christopher P. Buzzelli, Richard A. Luettich Jr., Sean P. Powers, Charles H. Peterson, Jesse E. Mcninch, James L. Pinckney, Hans W. Paerl

Faculty Publications

Bottom-water hypoxia (≤ 2 mg 1-1 dissolved oxygen [DO]) greatly modifies the benthic habitat of estuaries, depending upon spatial extent, duration, and frequency. Bottom-water hypoxia often develops under conditions of density stratification, which inhibits vertical mixing, and warm temperatures, which enhance biological oxygen demand. Long-term, mid-channel data from the Neuse River Estuary in North Carolina permitted evaluation of how stratification and temperature combined to affect DO concentrations at the bottom. Salinity stratification (DS) and water temperature (T) explained respectively 30 and 23% of the variance in bottom-water DO concentrations. The amount of salinity stratification required to induce bottom-water …

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Thin Laser Light Sheet Microscope For Microbial Oceanography, Eran Fuchs, Jules S. Jaffe, Richard A. Long, Farooq Azam Jan 2002

Thin Laser Light Sheet Microscope For Microbial Oceanography, Eran Fuchs, Jules S. Jaffe, Richard A. Long, Farooq Azam

Faculty Publications

Despite a growing need, oceanographers are limited by existing technological constrains and are unable to observe aquatic microbes in their natural setting. In order to provide a simple and easy to implement solution for such studies, a new Thin Light Sheet Microscope (TLSM) has been developed. The TLSM utilizes a well-defined sheet of laser light, which has a narrow (23 micron) axial dimension over a 1 mm x 1 mm field of view. This light sheet is positioned precisely within the depth of field of the microscope’s objective lens. The technique thus utilizes conventional microscope optics but replaces the illumination …

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Microscale Patchiness Of Bacterioplankton Assemblage Richness In Seawater, Richard A. Long, Farooq Azam Dec 2001

Microscale Patchiness Of Bacterioplankton Assemblage Richness In Seawater, Richard A. Long, Farooq Azam

Faculty Publications

We sought to test the hypothesis that bacterial species richness and composition vary at the millimeter scale in the marine pelagic environment, in response to the heterogeneous distribution of organic matter. To test this hypothesis, it was necessary to design and test a protocol to sample, lyse and analyze (by polymerase chain reaction/denaturing gradient gel electrophoresis [PCR-DGGE]) bacterioplankton species richness in a single microliter of seawater. Significant variation in bacterial species richness was found amongst 1 μl samples. Greater species richness was seen when seawater was enriched with diatom detritus. Examination of species richness at 2 mm intervals over a …

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Molecular Diversity, Structure And Domestication Of Grasses, Edward S. Buckler Iv, Jeffry M. Thornsberry, Stephen Kresovich Jun 2001

Molecular Diversity, Structure And Domestication Of Grasses, Edward S. Buckler Iv, Jeffry M. Thornsberry, Stephen Kresovich

Faculty Publications

Over the last 10,000 years, crop domestication has been the single most important human cultural development. Grasses are prominent among these crops, and provide the vast majority of the world's food. Similar traits have been selected during the domestication and breeding of these critically important grasses, and since they share a similar complement of genes, the same set of genes may have been selected. Even though the process of domestication occurred over the same 5000 to 10,000 year period, the domesticated grasses have major differences in genome structure, diversity, and life history. Molecular investigations of grass domestication have succeeded in …

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Shape Imprinting Due To Variable Disulfide Bonds In Polyacrylamide Gels, Andrew B. Greytak, Alexander Y. Grosberg, Toyoichi Tanaka Jun 2001

Shape Imprinting Due To Variable Disulfide Bonds In Polyacrylamide Gels, Andrew B. Greytak, Alexander Y. Grosberg, Toyoichi Tanaka

Faculty Publications

Through the use of variable disulfide crosslinkers, we have created polyacrylamide gels whose shape can be altered after polymerization. N,N'-bisacryloylcystamine is incorporated as a crosslinker, along with a smaller amount of a permanent crosslinker. After polymerization, the disulfide bonds are cleaved into thiols through reduction. By reoxidizing the thiols with the gel held in a new macroscopic shape, a new set of disulfide bonds is formed, and the gel is forced to adopt the new shape. Retension of the new shape improves with greater distortion from the original shape, as well as with increased concentration of variable …

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Variations In Bacterial Community Structure During A Dinoflagellate Bloom Analyzed By Dgge And 16s Rdna Sequencing, Laura B. Fandino, Lasse Riemann, Grieg F. Steward, Richard A. Long, Farooq Azam Jan 2001

Variations In Bacterial Community Structure During A Dinoflagellate Bloom Analyzed By Dgge And 16s Rdna Sequencing, Laura B. Fandino, Lasse Riemann, Grieg F. Steward, Richard A. Long, Farooq Azam

Faculty Publications

The relationship between bacterial 16S rRNA gene composition and carbon metabolism was analyzed during an intense dinoflagellate bloom off the Southern California coast during the spring of 1997. Bacterial numbers and rate processes, chlorophyll a, and the dissolved and particulate organic matter pools were measured during the bloom to provide a framework within which to assess bacterial community composition. Free bacteria were numerically dominant, generally comprising >90% of the total, and were responsible for >70% of bacterial production. Attached bacteria had higher cell-specific growth rates than free bacteria (range = 0.5 to 15.1 and 0.7 to 2.5 d-1 …

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Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg Jan 2001

Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg

Faculty Publications

Using a target-neighborhood approach with six annual dicot species in the Negev Desert of Israel, we tested whether neighborhood biomass constrained the upper limit of plant performance and if the slope of the upper boundary was correlated to species trait means, such as relative growth rate (RGR) and seed mass. Target individuals were measured in early spring and then collected at the onset of the dry season along with all naturally occurring neighbors within a 5-cm radius of the target. Using a minimum of 50 samples for each of the six target species, we found no significant relationships between target …

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Dna Binding Properties Of The Arabidopsis Floral Development Protein Aintegumenta, Staci Nole-Wilson, Beth A. Krizek Nov 2000

Dna Binding Properties Of The Arabidopsis Floral Development Protein Aintegumenta, Staci Nole-Wilson, Beth A. Krizek

Faculty Publications

The Arabidopsis protein AINTEGUMENTA (ANT) is a member of a plant-specific family of transcription factors (AP2/EREBP) that share either one or two copies of an approximately 70 amino acid region called the AP2 repeat. DNA binding activity has been demonstrated previously for members of this family containing a single AP2 repeat. Using an in vitro selection procedure, the DNA binding specificity of the two AP2 repeat containing protein ANT was found to be 5'-gCAC(A/G)N(A/T)TcCC(a/g)ANG(c/t)-3'. This consensus site is much longer than sites recognized by proteins containing a single AP2 repeat and neither AP2 repeat of ANT was alone capable of …

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Effect Of Harvest And Effective Population Size On Genetic Diversity In A Striped Bass Population, Marilyn Diaz, David S. Wethey, James Bulak, Bert Ely Nov 2000

Effect Of Harvest And Effective Population Size On Genetic Diversity In A Striped Bass Population, Marilyn Diaz, David S. Wethey, James Bulak, Bert Ely

Faculty Publications

A major factor that contributes to loss of genetic variation in natural populations is a small effective population size. In species with a complex life history that involves overlapping generations and delayed maturity, the impact of infrequent annual reproductive bottlenecks is likely to be small because effective population size is defined by the number of individuals contributing to a generation and not to a single year-class. The striped bass Morone saxatilis is a longlived species with overlapping generations and age structure, whose recreational and commercial importance has made it a target of intense harvest.We analyzed allele frequency fluctuation among juvenile …

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Regulation Of Sup Expression Identifies Multiple Regulators Involved In Arabidopsis Floral Meristem Development, Hajime Sakai, Beth A. Krizek, Steven E. Jacobsen, Elliot M. Meyerowitz Sep 2000

Regulation Of Sup Expression Identifies Multiple Regulators Involved In Arabidopsis Floral Meristem Development, Hajime Sakai, Beth A. Krizek, Steven E. Jacobsen, Elliot M. Meyerowitz

Faculty Publications

During the course of flower development, floral homeotic genes are expressed in defined concentric regions of floral meristems called whorls. The SUPERMAN ( SUP, also called FLO10 ) gene, which encodes a C2H2-type zinc finger protein, is involved in maintenance of the stamen/carpel whorl boundary (the boundary between whorl 3 and whorl 4) in Arabidopsis. Here, we show that the regulation of SUP expression in floral meristems is complex, consisting of two distinct phases, initiation and maintenance. The floral meristem identity gene LEAFY ( LFY ) plays a role in the initiation phase through at least two pathways, which …

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Aintegumenta Promotes Petal Identity And Acts As A Negative Regulator Of Agamous, Beth A. Krizek, Valerie Prost, Anthony Macias Aug 2000

Aintegumenta Promotes Petal Identity And Acts As A Negative Regulator Of Agamous, Beth A. Krizek, Valerie Prost, Anthony Macias

Faculty Publications

The Arabidopsis AINTEGUMENTA (ANT) gene has been shown previously to be involved in ovule development and in the initiation and growth of floral organs. Here, we show that ANT acts in additional processes during flower development, including repression of AGAMOUS (AG) in second whorl cells, promotion of petal epidermal cell identity, and gynoecium development. Analyses of ap2-1 ant-6 double mutants reveal that ANT acts redundantly with AP2 to repress AG in second whorl cells. The abaxial surface of ant petals contains features such as stomata and elongated, interdigitated cells that are not present on wild-type petals. …

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An Est-Enriched Comparative Map Of Brassica Oleracea And Arabidopsis Thaliana, Tien-Hung Lan, Terrye A. Delmonte, Kim P. Reischmann, Joel Hyman, Stanley P. Kowalski, Jim Mcferson, Stephen Kresovich, Andrew H. Paterson Jun 2000

An Est-Enriched Comparative Map Of Brassica Oleracea And Arabidopsis Thaliana, Tien-Hung Lan, Terrye A. Delmonte, Kim P. Reischmann, Joel Hyman, Stanley P. Kowalski, Jim Mcferson, Stephen Kresovich, Andrew H. Paterson

Faculty Publications

A detailed comparative map of Brassica oleracea and Arabidopsis thaliana has been established based largely on mapping of Arabidopsis ESTs in two Arabidopsis and four Brassica populations. Based on conservative criteria for inferring synteny, “one to one correspondence” between Brassica and Arabidopsis chromosomes accounted for 57% of comparative loci. Based on 186 corresponding loci detected in B. oleracea and A. thaliana, at least 19 chromosome structural rearrangements differentiate B. oleracea and A. thaliana orthologs. Chromosomal duplication in the B. oleracea genome was strongly suggested by parallel arrangements of duplicated loci on different chromosomes, which accounted for 41% of loci …

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Responses Of Phytoplankton And Pfiesteria-Like Dinoflagellate Zoospores To Nutrient Enrichment In The Neuse River Estuary, North Carolina, Usa, James L. Pinckney, Hans W. Paerl, Elin Haugen, Patricia A. Tester Jan 2000

Responses Of Phytoplankton And Pfiesteria-Like Dinoflagellate Zoospores To Nutrient Enrichment In The Neuse River Estuary, North Carolina, Usa, James L. Pinckney, Hans W. Paerl, Elin Haugen, Patricia A. Tester

Faculty Publications

The recently described toxic dinoflagellate Pfiestena piscicida and morphologically similar Pfiesteria-like dinoflagellates have become a major water quality issue with possible fish mortality and reported human health implications. The linkages between accelerated nutrient loading, eutrophication, and the proliferation of this group of dinoflagellates, however, are not well established for natural Systems. Phytoplankton pnmary production may provide a key link between nutrient inputs and potential outbreaks of Pfiesteria-like biflagellated zoospores in the Neuse River Estuary, North Carolina. The impacts of nutrient (NO3- -nitrogen and PO43- -phosphorus) supply rates, sediment-water column exchange, water column mixing, and phytoplankton prey …

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Nutrient Cycling In The Water Column Of A Subtropical Seagrass Meadow, Susan Ziegler, Ronald Benner Nov 1999

Nutrient Cycling In The Water Column Of A Subtropical Seagrass Meadow, Susan Ziegler, Ronald Benner

Faculty Publications

The cycling of nutrients was studied over a 16 mo period to determine how processes occurring between the water column and benthos influenced nutrient dynamics in a Thalassia testudinum dominated seagrass meadow. Nutrient concentrations were low and ranged from below detection to 0.59 µM ammonium (NH4+), 0.04 to 0.29 µM nitrate plus nitrite (NO3- + NO2-), and below detection to 0.22 µM soluble reactive phosphate (SRP). Water column and benthic fluxes of NO3- + NO2- and SRP were usually below detection. The benthic fluxes of NH4+ …

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Fish Kills And Bottom-Water Hypoxia In The Neuse River And Estuary: Reply To Burkholder Et Al., Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls Sep 1999

Fish Kills And Bottom-Water Hypoxia In The Neuse River And Estuary: Reply To Burkholder Et Al., Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls

Faculty Publications

No abstract provided.

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Film Formation By Marine Bacteria At A Model Fluid Interface, Vera Zutic, Nadica Ivosevic, Vesna Svetlicic, Richard A. Long, Farooq Azam Jun 1999

Film Formation By Marine Bacteria At A Model Fluid Interface, Vera Zutic, Nadica Ivosevic, Vesna Svetlicic, Richard A. Long, Farooq Azam

Faculty Publications

We have characterized the nonspecific interactions in the initial attachment and film formation by marine bacteria at a dynamic fluid interface: seawater/dropping mercury electrode. Experimental evidence is presented that bacteria readily establish molecular contact with the metal substrate without mediation of a conditioning film. Prevalence of hydrophobic over electrostatic interactions and the possible importance of Ca2+ bridging could be inferred. The attachment of individual bacterial cells is faster than their transport from the aqueous medium, as is the case in the transport-controlled adsorption of biopolymers. The cell aggregates yield distinct electrical attachment signals, allowing a comparison between cell-cell and …

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Dissolved Organic Carbon Cycling In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner May 1999

Dissolved Organic Carbon Cycling In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner

Faculty Publications

The cycling of dissolved organic matter (DOM) and its significance to ecosystem metabolism was studled over a 16 mo period in a Thalassia testudjnum dominated meadow. The benthos was usually net autotrophic (annual gross primary production to respiration ratio [P:R] = 1.3) while water column respiration (R) exceeded gross primary production (annual P:R = 0.3). Net fluxes of dissolved organic carbon (DOC) from the benthos primarily occurred in the light (0 to 18 mmol C m-2 d-1) and from seagrass-dominated areas, suggesting that release of DOC was mainly due to seagrass exudation. Net benthic DOC fluxes measured …

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Coupling Between Bacterioplankton Species Composition, Population Dynamics, And Organic Matter Degradation, Jarone Pinhassi, Farooq Azam, Johanna Hemphälä, Richard A. Long, Josefina Martinez, Ulla Li Zweifel, Åke Hagström Apr 1999

Coupling Between Bacterioplankton Species Composition, Population Dynamics, And Organic Matter Degradation, Jarone Pinhassi, Farooq Azam, Johanna Hemphälä, Richard A. Long, Josefina Martinez, Ulla Li Zweifel, Åke Hagström

Faculty Publications

To study the effect of substrate addition on short term bacterial population dynamics and species composition in seawater mesocosms were maintained with water collected off Scripps Pier (La Jolla, California USA) Protein enrichment (BSA) triggered a dynamic response from the microbial food web, whereas enrichment with starch had no effect. In the protein enriched mesocosm the number of both nucleoid-containing cells and metabolically active cells increased by 3.0 X 105 cells ml-1 from Day 1 to Day 4 In the same time period the density of a set of 31 phylogenetically different bacteria (α- and g-Proteobactena as well …

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Rainfall Stimulation Of Primary Production In Western Atlantic Ocean Waters: Roles Of Different Nitrogen Sources And Co-Limiting Nutrients, Hans W. Paerl, Joan D. Willey, Malia Go, Benjamin L. Peierls, James L. Pinckney, Marilyn L. Fogel Jan 1999

Rainfall Stimulation Of Primary Production In Western Atlantic Ocean Waters: Roles Of Different Nitrogen Sources And Co-Limiting Nutrients, Hans W. Paerl, Joan D. Willey, Malia Go, Benjamin L. Peierls, James L. Pinckney, Marilyn L. Fogel

Faculty Publications

Using shipboard bioassays, we examined the roles rainfall, individual and combined nutrients play in accelerating primary production in coastal, Gulf Stream and pelagic (Sargasso Sea) locations in the North Atlantic Ocean off North Carolina, USA, from 1993 to 1995. Photosynthetic CO2 fixation and net chlorophyll a (chl a) production were measured In replicated bioassays to assess individual and combined impacts of different constituents of atmospheric deposition, including natural rainfall, a synthetic rain mix, dissolved inorganic nitrogen (DIN; NH4+ ,NO3-), dissolved organic nitrogen (DON; urea),phosphorus (PO43-) and iron (as EDTA-chelated and …

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Effects Of Competition On Resource Availability And Growth Of A California Bunchgrass, Andrew R. Dyer, Kevin J. Rice Jan 1999

Effects Of Competition On Resource Availability And Growth Of A California Bunchgrass, Andrew R. Dyer, Kevin J. Rice

Faculty Publications

In California, little is known about the sensitivity of native bunchgrasses to competition or to changes in resource availability. We investigated the effect of nonnative annual vegetation on resource availability and growth of a native bunchgrass, Nassella pulchra, in a pair of factorial field experiments that incorporated effects of both interspecific and intraspecific competition as well as variation in soil depth. Plots of differing target densities and neighborhoods were used to assess changes in aboveground (light) and belowground (water) resource availability over multiple seasons in two sites with differing soil depth. N. pulchra grown without interspecific competitors grew larger …

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Principal Component Mapping Applied To Raman Microspectroscopy Of Fiber-Reinforced Polymer Composites, C. M. Stellman, K. S. Booksh, A. R. Muroski, M. P. Nelson, Michael L. Myrick Dec 1998

Principal Component Mapping Applied To Raman Microspectroscopy Of Fiber-Reinforced Polymer Composites, C. M. Stellman, K. S. Booksh, A. R. Muroski, M. P. Nelson, Michael L. Myrick

Faculty Publications

We describe the development and implementation of a spectroscopic Raman imaging system using Principal Component data analysis. Raman microspectroscopy followed by multivariate data analysis and principal component mapping has been used to investigate the spatial variations of chemical and physical properties at interfaces in glass-reinforced composites on the micrometer scale. A protocol for monitoring chemical and physical variances via multivariate statistics has been developed and a preliminary study of a "real world" glass-reinforced composite is presented. It is demonstrated that multivariate Raman imaging is more precisely interpretable than traditional univariate methods and that by appropriately choosing distinct spectral regions (such …

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Ecosystem Metabolism In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner Nov 1998

Ecosystem Metabolism In A Subtropical Seagrass-Dominated Lagoon, Susan Ziegler, Ronald Benner

Faculty Publications

Measurements of ecosystem gross primary production (GPP) and respiration (R) were made for 2 to 3 consecutive days on 10 occasions from February 1996 through June 1997 in the seagrass-dominated Laguna Madre (Texas, USA). Ecosystem GPP and R were quantified using 3 independent measurements including the open-water technique using dissolved oxygen (DO) and dissolved inorganic carbon (DIC) and the summation of discrete measurements of the water column and benthos. Diel curves of DIC were often influenced by water movement while the impact of water movement on DO was not apparent. This was attributed to the longer turnover time of DIC …

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Ecosystem Responses To Internal And Watershed Organic Matter Loading: Consequences For Hypoxia In The Eutrophying Neuse River Estuary, North Carolina, Usa, Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls May 1998

Ecosystem Responses To Internal And Watershed Organic Matter Loading: Consequences For Hypoxia In The Eutrophying Neuse River Estuary, North Carolina, Usa, Hans W. Paerl, James L. Pinckney, John M. Fear, Benjamin L. Peierls

Faculty Publications

The contrasting impacts of externally supplied (runoff) and internally generated (nutrient stimulated phytoplankton blooms) organic matter on oxygen (02) depletion were examined and evaluated in the eutrophic, salinity-stratified Neuse River Estuary, North Carolina, USA. This nitrogen (N)- limited estuary is experiencing increasing anthropogenic N loading from expanding urban, agricultural and industrial development in its watershed. Resultant algal blooms, which provided organic matter loads capable of causing extensive low 02 (hypoxic) and depleted 02 (anoxic) conditions, have induced widespread mortality of resident fin- and shellfish. Phytoplankton blooms followed periods of elevated N loading, except during extremely high …

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Differential Expression Of The Arabidopsis Nia1 And Nia2 Genes: Cytokinin-Induced Nitrate Reductase Activity Is Correlated With Increased Nia1 Transcription And Mrna Levels, Xiaodan Yu, Sujatha Sukumaran, László Márton Mar 1998

Differential Expression Of The Arabidopsis Nia1 And Nia2 Genes: Cytokinin-Induced Nitrate Reductase Activity Is Correlated With Increased Nia1 Transcription And Mrna Levels, Xiaodan Yu, Sujatha Sukumaran, László Márton

Faculty Publications

Nitrate reductase (NR) activity increased up to 14-fold in response to treatment of Arabidopsis thaliana seedlings with the cytokinin benzyladenine. NR induction was observed in seedlings germinated directly on cytokinin-containing medium, seedlings transferred to cytokinin medium, and seedlings grown in soil in which cytokinin was applied directly to the leaves. About the same level of induction was seen in both wild-type and Nia2-deletion mutants, indicating that increased NR activity is related to the expression of the minor NR gene, Nia1. The steady-state Nia1 mRNA level was increased severalfold in both wild-type and mutant seedlings after benzyladenine treatment. Transcript …

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Antisense Expression Of The Peptide Transport Gene Atptr2-B Delays Flowering And Arrests Seed Development In Transgenic Arabidopsis Plants, Wei Song, Serry Koh, Mihály Czakó, László Márton, Eliana Drenkard, Jeffrey M. Becker, Gary Stacey Jul 1997

Antisense Expression Of The Peptide Transport Gene Atptr2-B Delays Flowering And Arrests Seed Development In Transgenic Arabidopsis Plants, Wei Song, Serry Koh, Mihály Czakó, László Márton, Eliana Drenkard, Jeffrey M. Becker, Gary Stacey

Faculty Publications

Previously, we identified a peptide transport gene, AtPTRZ-B, from Arabidopsis thaliana that was constitutively expressed in all plant organs, suggesting an important physiological role in plant growth and development. To evaluate the function of this transporter, transgenic Arabidopsis plants were constructed expressing antisense or sense AtPTRZ-B. Genomic Southern analysis indicated that four independent antisense and three independent sense AtPTRZ-B transgenic lines were obtained, which was confirmed by analysis of the segregation of the kanamycin resistance gene carried on the T-DNA. RNA blot data showed that the endogenous AtPJRZ-B mRNA levels were significantly reduced in transgenic leaves and …

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Intraspecific And Diffuse Competition: The Response Of Nassella Pulchra In A California Grassland, Andrew R. Dyer, Kevin J. Rice May 1997

Intraspecific And Diffuse Competition: The Response Of Nassella Pulchra In A California Grassland, Andrew R. Dyer, Kevin J. Rice

Faculty Publications

In inland California grasslands, the high densities of alien annual species have altered the growing environment for native perennial grasses. Using variable-density plots, we measured the influence of intraspecific competition (conspecifics only) and diffuse competition (mixed-composition neighborhoods that include conspecifics) on growth and survival of Nassella pulchra, purple needlegrass. We assessed the effects of intraspecific and diffuse competition in weeded plots and unweeded plots, respectively, across a density gradient of N. pulchra plants (16–356 plants/m2). We used summer fire and spring sheep grazing to reduce diffuse competition in unweeded plots. The potential effect of rooting volume on competitive interactions …

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234Th And 210Pb Evidence For Rapid Ingestion Of Settling Particles By Mobile Epibenthic Megafauna In The Abyssal Ne Pacific, L. M. L. Lauerman, J. M. Smoak, Timothy J. Shaw, W. S. Moore, K. L. Smith Jr. May 1997

234Th And 210Pb Evidence For Rapid Ingestion Of Settling Particles By Mobile Epibenthic Megafauna In The Abyssal Ne Pacific, L. M. L. Lauerman, J. M. Smoak, Timothy J. Shaw, W. S. Moore, K. L. Smith Jr.

Faculty Publications

No abstract provided.

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A Transcription-Dependent Switch Controls Competence Of Adult Neurons For Distinct Modes Of Axon Growth, Deanna S. Smith, J.H. Pate Skene Jan 1997

A Transcription-Dependent Switch Controls Competence Of Adult Neurons For Distinct Modes Of Axon Growth, Deanna S. Smith, J.H. Pate Skene

Faculty Publications

Although maturing neurons undergo a precipitous decline in the expression of genes associated with developmental axon growth, structural changes in axon arbors occur in the adult nervous system under both normal and pathological conditions. Furthermore, some neurons support extensive regrowth of long axons after nerve injury. Analysis of adult dorsal root ganglion (DRG) neurons in culture now shows that competence for distinct types of axon growth depends on different patterns of gene expression. In the absence of ongoing transcription, newly isolated neurons can extend compact, highly branched arbors during the first day in culture. Neurons subjected to peripheral axon injury …

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