Digital Commons Network^™

Dynamics And Distribution Of Natural And Human-Caused Hypoxia, N N. Rabalais, R J. Diaz, L A. Levin, R. Eugene Turner, N N. Rabalais, J Zhang

Faculty Publications

Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen re-aeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (< 2 mg L-1, or approximately 30% saturation) can form, therefore, under 'natural' conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords. Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed. Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased surface water temperature as the global climate warms, is sufficient to worsen hypoxia where it currently exists and facilitate its formation in additional waters. Increased precipitation that increases freshwater discharge and flux of nutrients will result in increased primary production in the receiving waters up to a point. The interplay of increased nutrients and stratification where they occur will aggravate and accelerate hypoxia. Changes in wind fields may expand oxygen minimum zones onto more continental shelf areas. On the other hand, not all regions will experience increased precipitation, some oceanic water temperatures may decrease as currents shift, and frequency and severity of tropical storms may increase and temporarily disrupt hypoxia more often. The consequences of global warming and climate change are effectively uncontrollable at least in the near term. On the other hand, the consequences of eutrophication-induced hypoxia can be reversed if long-term, broad-scale, and persistent efforts to reduce substantial nutrient loads are developed and implemented. In the face of globally expanding hypoxia, there is a need for water and resource managers to act now to reduce nutrient loads to maintain, at least, the current status.

Natural And Human-Induced Hypoxia And Consequences For Coastal Areas: Synthesis And Future Development, J. Zhang, D. Gilbert, A.J. Gooday, L. Levin, S.W.A. Naqvi, J.J. Middelburg, M. Scranton, W. Ekau, A. Peña, B. Dewitte, T. Oguz, P.M.S. Monteiro, E. Urban, N.N. Rabalais, V. Ittekkot, W.M. Kemp, O. Ulloa, R. Elmgren, E. Escobar-Briones, A.K. Van Der Plas

Faculty Publications

No abstract provided.

Gain Control In Ca1 Pyramidal Cells Using Changes In Somatic Conductance., Fernandez Fr, White Ja

Faculty Publications

No abstract provided.

The Mechanism Of Abrupt Transition Between Theta And Hyper-Excitable Spiking Activity In Medial Entorhinal Cortex Layer Ii Stellate Cells., Kispersky T, White Ja, Rotstein Hg

Faculty Publications

No abstract provided.

Synaptically Activated Burst-Generating Conductances May Underlie A Group-Pacemaker Mechanism For Respiratory Rhythm Generation In Mammals, Christopher A. Del Negro, John A. Hayes, Ryland W. Pace, Benjamin R. Brush, Ryoichi Teruyama, Jack L. Feldman

Faculty Publications

Breathing, chewing, and walking are critical life-sustaining behaviors in mammals that consist essentially of simple rhythmic movements. Breathing movements in particular involve the diaphragm, thorax, and airways but emanate from a network in the lower brain stem. This network can be studied in reduced preparations in vitro and using simplified mathematical models that make testable predictions. An iterative approach that employs both in vitro and in silico models argues against canonical mechanisms for respiratory rhythm in neonatal rodents that involve reciprocal inhibition and pacemaker properties. We present an alternative model in which emergent network properties play a rhythmogenic role. Specifically, …

Intracellular Ph Regulation In Isolated Trout Gill Mitochondrion-Rich (Mr) Cell Subtypes: Evidence For Na+/H+ Activity, Scott K. Parks, Martin Tresguerres, Fernando Galvez, Greg G. Goss

Faculty Publications

We have studied intracellular pH (pHi) recovery in isolated trout gill mitochondrion-rich (MR) cells following acidification by the NH4Cl pre-pulse technique. Within a mixed MR cell population, one cell type displayed Na+-independent pHi recovery while the other cell type lacked a Na+-independent pHi recovery. Cells displaying Na+ independent recovery exhibited a significantly higher buffering capacity compared to cells lacking Na+-independent pHi recovery. Cells displaying Na+ independent recovery were identified as PNA+ (peanut lectin agluttinin binding) MR cells while those unable to recover were identified as PNA- (non-peanut lectin agluttinin binding) MR cells. Therefore, recovery from acidification in the absence of …

Social Status Regulates Kisspeptin Receptor Mrna In The Brain Of Astatotilapia Burtoni, Brian P. Grone, Karen P. Maruska, Wayne J. Korzan, Russell D. Fernald

Faculty Publications

The brain controls reproduction in response to relevant external and internal cues. Central to this process in vertebrates is gonadotropin-releasing hormone (GnRH1) produced in neurons of the hypothalamic-preoptic area (POA). GnRH1 released from the POA stimulates pituitary release of gonadotropins, which in males causes sperm production and concomitant steroid hormone release from the testes. Kisspeptin, a neuropeptide acting via the kisspeptin receptor (Kiss1r), increases GnRH1 release and is linked to development of the reproductive system in mammals and other vertebrates. In both fish and mammals, kiss1r mRNA levels increase in the brain around the time of puberty but the environmental …

Expression, Localization And Interaction Of Snare Proteins In Arabidopsis Are Selectively Altered By The Dark, Naohiro Kato, Huancan Bai

Faculty Publications

A method to detect binary interactions among SNAREs, membrane proteins mediating vesicle fusion, in Arabidopsis cells was established. In this method, a pair of recombinant SNAREs is first expressed within Arabidopsis protoplasts at levels similar to their endogenous proteins in 96-well plates. Changes of the interaction are then detected by luminescence. Here, we report that the interaction of SYP122 and VAMP721, a SNARE pair mediating exocytosis, is enhanced when Arabidopsis protoplasts are incubated in the dark. Microscopic observation of plants expressing GFPSYP122 by the syp122 promoter suggests SYP122 is expressed in the root tip when the seedlings are grown in …

Gumbo Yearbook, Class Of 2010, Louisiana State University And Agricultural And Mechanical College

Gumbo Yearbook

The Gumbo yearbook chronicles the entire academic year at LSU. In words and especially photos, the Gumbo shows the people, places, and events that make each year unique. In addition to formal portraits of schools and departments, the book contains hundreds of snapshots of students with their friends and dozens of pages showcasing organizations.

The 2010 Gumbo was published with a DVD containing a video yearbook, as well as a PDF. Those files are linked below.

Engaging With The Politics Of Determinist Environmental Thinking, Andrew Sluyter

Faculty Publications

No abstract provided.

In The Shadow Of Slavery: Africa’S Botanical Legacy In The Atlantic World, Andrew Sluyter

Faculty Publications

No abstract provided.

Renegotiating Barbuda's Commons: Recent Changes In Barbudan Open-Range Cattle Herding, Andrew Sluyter, Amy E. Potter

Faculty Publications

Barbuda remains little developed and sparsely populated relative to its neighbors in the Leeward Lesser Antilles, a rather extraordinary and relatively unknown Caribbean place. Much of its distinctiveness derives from the communal land-tenure system, itself rooted in three centuries of open-range cattle herding. Yet, as revealed through interviews, newspaper archives, and landscape observations, openrange cattle herding has declined over the past three decades, with related changes in land tenure. As the new Barbuda Land Act came into effect in 2008, codifying the communal tenure system, the very landscape elements that manifest open-range herding have become obscure. In particular, the rock-walled …

The Hispanic Atlantic's Tasajo Trail, Andrew Sluyter

Faculty Publications

Produced along the Río de la Plata during the nineteenth century, shipped to Havana, and consumed by African slaves, the salt-cured beef known as tasajo affected both of those places and, to some degree, the Atlantic world in general. Initial exploration of the tasajo trail that connected Buenos Aires and Cuba employs primary sources such as nineteenth-century descriptions and shipping records to characterize the landscapes, places, routes, and agents of the largely unexplored research territory of that anomalous commodity: one that, unlike others such as sugar, slaves not only produced but also consumed; one that underpinned more prominent, latitudinal transatlantic …

Brucella Species Survey In Polar Bears (Ursus Maritimus) Of Northern Alaska, Todd M. O'Hara, Darce Holcomb, Philip Elzer, Jessica Estepp, Quinesha Perry, Sue Hagius, Cassandra Kirk

Faculty Publications

We report on the presence of specific antibodies to Brucella spp. and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003-2006. Based on numerous known stressors (e.g., climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears. Considering these changes, it is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways. Brucella or specific antibodies to Brucella spp. has been reported in marine mammals. Various assays were used to elucidate the pathway or source of exposure (e.g., "marine" vs. …

Testing Protozoacidal Activity Of Ligand-Lytic Peptides Against Termite Gut Protozoa In Vitro (Protozoa Culture) And In Vivo (Microinjection Into Termite Hindgut), Claudia Husseneder, Amit Sethi, Lane Foil, Jennifer Delatte

Faculty Publications

We are developing a novel approach to subterranean termite control that would lead to reduced reliance on the use of chemical pesticides. Subterranean termites are dependent on protozoa in the hindguts of workers to efficiently digest wood. Lytic peptides have been shown to kill a variety of protozoan parasites (Mutwiri et al. 2000) and also protozoa in the gut of the Formosan subterranean termite, Coptotermes formosanus (Husseneder and Collier 2009). Lytic peptides are part of the nonspecific immune system of eukaryotes, and destroy the membranes of microorganisms (Leuschner and Hansel 2004). Most lytic peptides are not likely to harm higher …

A Phylogenetic Approach To Disentangling The Role Of Competition And Habitat Filtering In Community Assembly Of Neotropical Forest Birds, Juan Pablo Gómez, Gustavo A. Bravo, Robb T. Brumfield, José G. Tello, Carlos Daniel Cadena

Faculty Publications

Methods that assess patterns of phylogenetic relatedness, as well as character distribution and evolution, allow one to infer the ecological processes involved in community assembly. Assuming niche conservatism, assemblages should shift from phylogenetic clustering to evenness with decreasing geographic scale because the relative importance of mechanisms that shape assemblages is hypothesized to be scale-dependent. Whereas habitat filtering is more likely to act at regional scales because of increased habitat heterogeneity that allows sorting of ecologically similar species in contrasting environments, competition is more likely to act at local scales because low habitat heterogeneity provides few opportunities for niche partitioning. We …

Third-Wave Feminism In Select Young Adult Literature, Colleen Mckinney

Honors Capstones

No abstract provided.

Louisiana Agriculture Winter, 2010, Lsu Agcenter

Louisiana Agriculture

No abstract provided.

2010 Louisiana Summary: Agriculture And Natural Resources, Lsu Agcenter

Louisiana Summary: Agriculture and Natural Resources

This publication tabulates the value of Louisiana agriculture in 2010. Agents and specialists of the Louisiana Cooperative Extension Service, as well as other agencies – both private and public – compiled the data. Their analysis focuses on the animal, forestry, fisheries, plant and wildlife commodities that comprise our vital agricultural industry. Agricultural and natural resource industries contribute significantly to our state’s economy with the potential for increased economic benefits and job creation through value-added processing in urban and rural communities throughout Louisiana.

The 2010 production year was much improved over the previous two years for most in the state’s food …

Nuclear Actin-Related Proteins At The Core Of Epigenetic Control, Richard B. Meagher, Muthugapatti K. Kandasamy, Aaron P. Smith, Elizabeth C. Mckinney

Faculty Publications

Nuclear Actin-Related Proteins (ARPs) and actin combine as heterodimers to bind a large helicase subunit and form a core complex essential to the assembly and function of most chromatin remodeling and modifying machines. They are the most common shared subunits of these large and diverse assemblies in eukaryotes. We recently argued that most nuclear ARPs evolved directly from actin prior to the divergence of the eukaryotic kingdoms and did not evolve from pre-existing ARPs.2 Arabidopsis plants defective in nuclear ARP4, ARP5, ARP6 or ARP7 have extreme developmental phenotypes. Our recent publication demonstrates that ARP5-defective plants are not only dwarfed and …

Targeted Gene Replacement By Homologous Recombination In Drosophila Stimulates Production Of Second-Site Mutations, Swarnava Roy, Craig M. Hart

Faculty Publications

Gene replacement by homologous recombination is a powerful technique for generating mutations in Drosophila. While using this technique for the BEAF gene, we encountered non-targeted lethal mutations on the target chromosome that complicated the analysis of the BEAF mutations until they were discovered and removed by meiotic recombination. Subsequent experiments indicated that the gene-targeting method leads to a modest but significant three-fold increase in the rate of production of non-targeted lethal mutations. It is important to be aware of this phenomenon when using this method. © 2010 Landes Bioscience.

Endoreplication Controls Cell Fate Maintenance, Jonathan Bramsiepe, Katja Wester, Christina Weinl, Farshad Roodbarkelari, Remmy Kasili, John C. Larkin, Martin Hülskamp, Arp Schnittger

Faculty Publications

Cell-fate specification is typically thought to precede and determine cell-cycle regulation during differentiation. Here we show that endoreplication, also known as endoreduplication, a specialized cell-cycle variant often associated with cell differentiation but also frequently occurring in malignant cells, plays a role in maintaining cell fate. For our study we have used Arabidopsis trichomes as a model system and have manipulated endoreplication levels via mutants of cell-cycle regulators and overexpression of cell-cycle inhibitors under a trichome-specific promoter. Strikingly, a reduction of endoreplication resulted in reduced trichome numbers and caused trichomes to lose their identity. Live observations of young Arabidopsis leaves revealed …

Pr10 Expression In Maize And Its Effect On Host Resistance Against Aspergillus Flavus Infection And Aflatoxin Production, Zhi Yuan Chen, Robert L. Brown, Kenneth E. Damann, Thomas E. Cleveland

Faculty Publications

Maize (Zea mays L.) is a major crop susceptible to Aspergillus flavus infection and subsequent contamination with aflatoxins, the potent carcinogenic secondary metabolites of the fungus. Protein profiles of maize genotypes resistant and susceptible to A. flavus infection and/or aflatoxin contamination have been compared, and several resistance-associated proteins have been found, including a pathogenesis-related protein 10 (PR10). In this study, RNA interference (RNAi) gene silencing technology was employed to further investigate the importance of PR10. An RNAi gene silencing vector was constructed and introduced into immature Hi II maize embryos through both bombardment and Agrobacterium infection procedures. PR10 expression was …

Components, Volume 6 (2010), Lsu Center For Computation & Technology

Components

No abstract provided.

Darwinian Populations And Natural Selection, Grant Ramsey, Hope Hollocher, Agustín Fuentes, Charles H. Pence, Edwin Siu

Faculty Publications

No abstract provided.

Research Matters Summer 2010, Louisiana State University And Agricultural & Mechanical College

Research Matters & RNR Newsletters

Research Matters is a publication which highlights ongoing research, international travel experiences, classroom happenings and degree program developments of and for the School of Renewable Natural Resources' students and faculty.

Olaudah Equiano, Autobiography, And Ideas Of Culture, Sarah Brophy

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

The Dynamics Of Goethe's Novelle The Never-Ending Journey To Newton's Burg, Heather I. Sullivan

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

The Whale-Propelled Vessel And Other Leaps Of Imagination As Autobiographical Metaphors In Adelbert Von Chamisso's Travel Diary Of The 1815-1818 Romanzoff Expedition, Johann J. K. Reusch

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.

Book Reviews

1650-1850: Ideas, Aesthetics, and Inquiries in the Early Modern Era

No abstract provided.