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Articles 961 - 990 of 1043

Full-Text Articles in Biology

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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The Reproductive Biology And Edaphic Characteristics Of A Rare, Gynodioecious Saxifage: Saxifraga Bryophora Var. Tobiasiae (Saxifragaceae), Kimberly Pierson May 1999

The Reproductive Biology And Edaphic Characteristics Of A Rare, Gynodioecious Saxifage: Saxifraga Bryophora Var. Tobiasiae (Saxifragaceae), Kimberly Pierson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

I examined the reproductive biology and general ecology of Saxifraga bryophora var. tobiasiae, a rare saxifrage endemic to the West Salmon River Mountains of central Idaho. Saxifraga bryophora var. tobiasiae combines asexual reproduction via bulbils with a sexual mixed-mating system. Flower production occurred in 1996 only, whereas bulbil production occurred in 1995, 1996, and 1997. Bulbil production precedes floral bud formation and is the dominant form of reproduction. When flowering occurs, outcrossing is promoted by protandry and the gynodioecious mating system found in all populations. No autogamous or agamospermous seed set was observed in either female or hermaphrodite flowers, …

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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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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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The Effects Of Pool Size On The Microinvertebrate Populations Of Chaney Lake, An Ephemeral Wetland Located In Bowling Green, Kentucky, Shannon Gaines May 1998

The Effects Of Pool Size On The Microinvertebrate Populations Of Chaney Lake, An Ephemeral Wetland Located In Bowling Green, Kentucky, Shannon Gaines

Mahurin Honors College Capstone Experience/Thesis Projects

Studies concerning the microinvertebrate communities of differing pool sizes were conducted at Chaney Lake, an ephemeral, karst wetland located in Bowling Green, Kentucky. As the lake begins to dry in the early summer, smaller, isolated ponds begin to form. Several ponds of various sizes were marked for analysis. Microinvertebrate samples and physiochemical readings were taken at each of the sites and were counted in the lab. T-tests were performed on the samples to determine if the microinvertebrate densities differed between ponds that dried later in the season as opposed to those that dried earlier. Ostracoda densities of the late dry …

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The Influence Of Biology Education On Attitudes To Humanity And Worldpeace, Yalçın Yetki̇n Jan 1998

The Influence Of Biology Education On Attitudes To Humanity And Worldpeace, Yalçın Yetki̇n

Turkish Journal of Biology

The purpose of this study was to determine whether biology education has any effect on behaviour and opinions with regard to humanity and world peace. The subjects were 37 student volunteers, 19 male and 18 female, from the Biology Department of Atatürk University. They were asked what influence biology education has on individual peace of mind and attitudes to world peace. The students responses indicated that, owing to their biology education, they have greater self-awareness (46.9%), are better able to think in a balanced way and to find their place in society. They also reported a greater capacity to love …

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Partial Sequencing Of A Balbiani Ring Gene And Development Of A Molecular Probe, Kerri Ann Kurzeja Jan 1998

Partial Sequencing Of A Balbiani Ring Gene And Development Of A Molecular Probe, Kerri Ann Kurzeja

Seton Hall University Dissertations and Theses (ETDs)

The Environmental Protection Agency is currently developing sediment quality criteria in order to protect the nation's water sources. In order to assist in the development of standards for the disposal of heavy metals, our laboratory is undergoing sediment toxicity studies on Chironomus riparius. It is an EPA approved test organism that spends most of its life in the sediment. Following a previous study (Cochrane et al., 1994), the organism's response to heavy metals will be monitored on the genetic level. Several genes, including a Balbiani ring (BR) gene, which was the focus of this thesis, will be studied to determine …

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Phylogenetic Placement Of African Cornus: Evidence Of Nuclear Rdna, Scott Myers Dec 1997

Phylogenetic Placement Of African Cornus: Evidence Of Nuclear Rdna, Scott Myers

Mahurin Honors College Capstone Experience/Thesis Projects

The genus Comus (the dogwoods) contains 50 species that have been divided into nine subgenera. One of these species, C. volkensii, has been segregated into the subgenus Ajrocrania. Previous studies combined morphological, anatomical, and chemical data to produce a hypothesis of evolutionary relationships that placed the subg. Afrocrania as a segregate lineage sister to the subg. Comus, and placed the Ajrocrania/Comus lineage sister to the big-bracted dogwoods (Murrell 1997). The subgenus Afrocrania has been examined morphologically, anatomically, and palynologically; however, it was not sequenced in Xiang's (1993) analysis of rbcL (chloroplast) sequence data, or in her analysis of the matK …

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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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Internal Oral Anatomy: A Comparative Analysis Of The Phyllomedusinae (Anura:Hylidae), Erin B. Hines Jan 1997

Internal Oral Anatomy: A Comparative Analysis Of The Phyllomedusinae (Anura:Hylidae), Erin B. Hines

Honors Theses

The internal oral anatomy of phyllomedusines has only been described for Agalychnis callydrias using light microscopy. Herein, we compare the internal oral anatomy of the genera Phyllomedusa, Agalychnis, Pachymedusa, and Phasmahyla, using SEM methodology. Tadpoles of ten species were prepared using standard SEM techniques; these larvae ranged from Gosner stages 34-39. Phasmahyla has a unique prenarial arena with three well developed pre-narial arena papillae, whereas the other genera possess the prenarial arena papillae in a semicircular arrangement with the opening directed posteriorly. Pachymedusa differs from Phyllomedusa and Agalychnis by having a low, straight-edge, median ridge; also, its buccal floor arena …

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Law And Biology: Toward An Integrated Model Of Human Behavior, Owen D. Jones Jan 1997

Law And Biology: Toward An Integrated Model Of Human Behavior, Owen D. Jones

Vanderbilt Law School Faculty Publications

As first year law students unhappily discover, the meaning of "law" is frustratingly protean, shifting by usage and user. Depending on whom you ask, law is a system of rules, a body of precedents, a legislative enactment, a collection of norms, a process by which social goals are pursued, or some dynamic mixture of these. Law's principal purpose is to define and protect individual rights, to ensure public order, to resolve disputes, to redistribute wealth, to dispense justice, to prevent or compensate for injury, to optimize economic efficiency, or perhaps to do something else. And yet one thing is irreducibly …

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Evaluation Of The Effects Of Afff Inputs On The Vip Biological Nutrient Removal Process And Pass-Through Toxicity. Phase 1a. Volume Ii. Appendix Vii. Acute Toxicity Test Results, Mujde Erten-Unal, Gary C. Schafran Jan 1997

Evaluation Of The Effects Of Afff Inputs On The Vip Biological Nutrient Removal Process And Pass-Through Toxicity. Phase 1a. Volume Ii. Appendix Vii. Acute Toxicity Test Results, Mujde Erten-Unal, Gary C. Schafran

Civil & Environmental Engineering Faculty Publications

This report discusses the results of a bench scale study conducted to evaluate the potential inhibitory effects of untreated AFFF wastewater to the Virginia Initiative Plant VIP biological nutrient removal process. A bench-scale study was conducted to evaluate the potential inhibitory effects of untreated AFFF wastewater to the nitrification process of the Virginia Initiative Plant biological nutrient removal system. Under this testing, bench-scale reactors simulating the nitrification process were loaded at various AFFF concentrations and the influence on the process performance was evaluated. The purpose of this effort was to determine the level of AFFF that could be incorporated into …

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The Effects Of Adrenergic And Cholinergic Stimulation On Skin Gland Secretions In The Dwarf African Frog Hymenochirus Curtipes, Daniel H. Gong Jan 1997

The Effects Of Adrenergic And Cholinergic Stimulation On Skin Gland Secretions In The Dwarf African Frog Hymenochirus Curtipes, Daniel H. Gong

University of the Pacific Theses and Dissertations

Many studies have been done on the neural control of serous gland secretion in the skin of frogs and newts. However, no studies have been published on the effects of adrenergic and cholinergic neurotransmitters on the sexually dimorphic breeding glands of male frogs. The present study examined the effects of neurotransmitters on the serous and breeding glands of Hymenochirus curtipes. Explants of dorsal skin and postaxial skin (containing whole breeding glands) were incubated in vitro with epinephrine, norepinephrine or acetylcholine for 30 minutes. The explants were then preserved and examined histologically for signs of secretion. The area and perimeter of …

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Biology: What One Needs To Know, Ursula Goodenough Dec 1996

Biology: What One Needs To Know, Ursula Goodenough

Biology Faculty Research

Biology on this planet represents an astonishing experiment in carbon-based chemistry which, over billions of years, has generated billions of species adapted to countless major and minor fluctuations in ecological circumstances. In one sense there is no way to generalize about biology. While biological activities can all be ultimately explained by physical laws (like everything else in the universe), it is the emergent intensely particular properties of organisms that most interest us. This essay represents an attempt to describe some of the more prominent patterns that emerge from the sea of biological particularities, patterns that present many opportunities for religious …

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Modeling Interactions Of Browsing Predation, Infaunal Activity And Recruitment In Marine Soft-Sediment Habitats, Sara M. Lindsay, David S. Wethey, Sarah A. Woodin Oct 1996

Modeling Interactions Of Browsing Predation, Infaunal Activity And Recruitment In Marine Soft-Sediment Habitats, Sara M. Lindsay, David S. Wethey, Sarah A. Woodin

Faculty Publications

In marine soft-sediment habitats, the sediment surface is altered by activities of sediment dwellers (infauna). Such biogenic disturbance can influence recruitment success if settling larvae and juveniles avoid disturbed sites or if juveniles die as a result of disturbance after settling. Because infauna commonly lose exposed body parts to browsing predators and disturb less sediment as a result, we developed a simulation model to examine the interactions between browsing predation, infaunal adult activity, and recruitment. Sediment disturbance in the model was based on data for the polychaete Abarenicola pacifica. We simulated the activity of two general types of predators: prey …

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Settlement And Early Post-Settlement Survival Of Sessile Marine Invertebrates On Topographically Complex Surfaces: The Importance Of Refuge Dimensions And Adult Morphology, Linda J. Walters, David S. Wethey Jun 1996

Settlement And Early Post-Settlement Survival Of Sessile Marine Invertebrates On Topographically Complex Surfaces: The Importance Of Refuge Dimensions And Adult Morphology, Linda J. Walters, David S. Wethey

Faculty Publications

We predicted that both refuge dimension and growth form would influence settlement and short-term post-settlement success (≤7 d) of sessile marine invertebrates that live attached to hard substrata in low energy environments. Individuals with unlimited attachment to the substrata should rapidly be protected by their growth form, thus decreasing their need to settle in refuges and limiting the length of time any locations on heterogeneous substrata act as refuges. Alternatively, organisms with limited attachment to the substrata should remain susceptible to the causes of mortality for a longer time, and as a result should settle in high quality refuges (sites …

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Abundant Protein-Containing Particles In The Sea, Richard A. Long, Farooq Azam Jun 1996

Abundant Protein-Containing Particles In The Sea, Richard A. Long, Farooq Azam

Faculty Publications

The interaction of bacteria with particulate organic matter has implications for organic matter cycling and bacterial ecology in the ocean. Until recently, the focus has been on 'classical' particles visible by unaided eye (marine snow) or light microscopy. Recent discoveries of several new types of abundant particles, from sub-micrometer to sub-marine snow, are changing our ideas of the physical and chemical nature of the particle field with which pelagic bacteria interact. Previous workers have discovered polysaccharide-containing (Alcian Blue stainable) transparent exopolymer particles (TEP) ranging from 3 to 100s of micrometers. Looking for additional components of the sub-marine snow particle field, …

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Effects Of High-Molecular-Weight Dissolved Organic Matter On Nitrogen Dynamics In The Mississippi River Plume, Wayne S. Gardner, Ronald Benner, Rainer M.W. Amon, James B. Cotner Jr., Joann F. Cavaletto, Jeffrey R. Johnson Mar 1996

Effects Of High-Molecular-Weight Dissolved Organic Matter On Nitrogen Dynamics In The Mississippi River Plume, Wayne S. Gardner, Ronald Benner, Rainer M.W. Amon, James B. Cotner Jr., Joann F. Cavaletto, Jeffrey R. Johnson

Faculty Publications

The dynamics of N and its interactions with labile dissolved organic C (DOC), bacteria, and phytoplankton were studied to determine potential effects of dissolved organic matter (DOM) and light on N dynamics in surface waters of the Mississippi River (USA) plume in the Gulf of Mexico. Bacterial uptake of added labeled N compounds ( 15NH4+ or 15N-labeled dissolved free amino acids. DFAA) was stimulated more by high-molecular-weight (HMW, >l kDa) DOM than by low-molecular-weight (LMW, < l kDa) DOM. An index that inversely indicated the presence of labile DOC was defined as the fraction of assimilated Amino acid-15N that was Recovered as 15N -Ammonium (ANRA), following the additions of high-levels (4 µM) of 15N -DFAA. …

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The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George Jan 1996

The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George

Scholarship

Planktotrophy is a relatively common developmental mode among bathyal and abyssal echinoderms, but the sources of food used by deep-sea planktotrophic larvae remain generally unknown. Very few deep-sea echinoderm larvae have been collected in plankton samples, so we do not know whether larvae migrate to the euphotic zone to feed or if they rely on bacteria or detritus at greater depths. We approached this question indirectly by investigating whether larvae of bathyal echinoids can tolerate the temperatures they would encounter in the euphotic zone and whether they possess sufficient energy stores to migrate to the euphotic zone without feeding. Twenty-four …

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Transport And Metabolism Of Alanine And Palmitic Acid By Field-Collected Larvae Of Tedania Ignis (Porifera, Demospongiae): Estimated Consequences Of Limited Label Translocation, William B. Jaeckle Oct 1995

Transport And Metabolism Of Alanine And Palmitic Acid By Field-Collected Larvae Of Tedania Ignis (Porifera, Demospongiae): Estimated Consequences Of Limited Label Translocation, William B. Jaeckle

Scholarship

The epidermis of larvae of Tedania ignis(Porifera, Demospongiae) is uniformly ciliated except for the posterior pole. The epidermal cells are long, columnar, and monociliate; each cilium arises from an epidermal crypt; symbiotic bacteria were not observed in larval cells. These lecithotrophic ("nonfeeding") larvae can feed by assimilating dissolved organic materials (DOM) from seawater. Larvae transported both the amino acid alanine (mean = 2.73 pmol larva-1 h-1; [S] = 1 µM) and the fatty acid palmitic acid (mean = 16.27 pmol larva-1 h-1; [S] = 1 µM) from seawater. Following assimilation, the …

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Cells Are Not Just Bags Of Water: A Personal Appreciation Of The Work Of Dr. Brij L. Gupta And His Contribution To Biological X-Ray Microanalysis, Alice Warley Aug 1995

Cells Are Not Just Bags Of Water: A Personal Appreciation Of The Work Of Dr. Brij L. Gupta And His Contribution To Biological X-Ray Microanalysis, Alice Warley

Scanning Microscopy

This paper surveys the contribution made by the work of Dr. B.L. Gupta to the science of biological X-ray microanalysis. A brief biographical sketch of Brij's early years is given, this is followed by considerations about the models for water transport across epithelia. The ultrastructural and histochemical studies carried out by Brij Gupta and colleagues are reviewed to introduce the historical need for the use of EPXMA for the study of ion and water transport in epithelia. The outstanding contribution made by Brij Gupta's work in this field is outlined, and his understanding of the subcellular distribution ions in other …

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Impacts Of Seasonality And Nutrients On Microbial Mat Community Structure And Function, James L. Pinckney, Hans W. Paerl, M. Fitzpatrick Jul 1995

Impacts Of Seasonality And Nutrients On Microbial Mat Community Structure And Function, James L. Pinckney, Hans W. Paerl, M. Fitzpatrick

Faculty Publications

To understand the mechanisms responsible for seasonal fluctuations in growth and N2 fixation in intertidal microbial mat communities, we quantified seasonal changes in mat community composition, related these changes to diel and seasonal N2 fixation rates, and evaluated community responses (growth, N2fixation, composition) to long-term (22 d) nutrient addition bioassays. A temperate intertidal cyanobacterial mat community, located in coastal North Carolina, USA, was sampled at monthly intervals for 1 yr (1993-94) to determine changes in community composition. The abundances of major phototrophic groups were quantified based on the relative concentrations of taxaspecific photopigments (chlorophylls and carotenoids). …

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The Criminological Significance Of The Comparative Analysis Of Serum Albumins Using Electrophoresis And Immuno Gel Diffusion, Rhonda E. Ross-Ries May 1995

The Criminological Significance Of The Comparative Analysis Of Serum Albumins Using Electrophoresis And Immuno Gel Diffusion, Rhonda E. Ross-Ries

Whittier Scholars Program

Scientists and forensic experts are making use of macromolecules and their separation. Proteins are unique macromolecules produced by individuals and have provided key evolutionary genetic relationships. Two of the most common techniques used to separate proteins for analyzation electrophoresis and the Ouchterlony technique. The purpose of this comparative analysis project was to broaden the researcher’s laboratory skills to compare the two techniques in terms of efficiency,, cost efficiency, accuracy of results, and interpretation of results. Albumins were chosen for analysis because these proteins are known to be important to biology and are in great concentration in blood plasma.

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Community Metabolism And Nutrient Cycling In The Mississippi River Plume: Evidence For Intense Nitrification At Intermediate Salinities, Joseph D. Pakulski, Ronald Benner, Rainer Amon, Brian Eadie, Terry Whitledge Feb 1995

Community Metabolism And Nutrient Cycling In The Mississippi River Plume: Evidence For Intense Nitrification At Intermediate Salinities, Joseph D. Pakulski, Ronald Benner, Rainer Amon, Brian Eadie, Terry Whitledge

Faculty Publications

Community respiration, net nutrient fluxes and heterotrophic bacterial production were investigated in the Mississippi River (USA) plume during May 1992 using dark bottle incubations of unfiltered water. Highest rates of community O2 consumption and dissolved inorganic carbon regeneration were observed at intermediate (10 to 27%0) plume salinities. Plume surface 02 consumption rates were 2- to 4-fold greater than rates reported previously during the summer and winter. Heterotrophic bacterial production ([3H]-leucine incorporation) was also highest at intermediate salinities and 2- to 4-fold greater than rates reported from other seasons. Net regeneration of NH4+ …

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Biology Of The Tao, Matthew D. Sellers Jan 1995

Biology Of The Tao, Matthew D. Sellers

Whittier Scholars Program

Much of this project is merely based on perspective. My perspective, that of the philosophies that I am attempting to highlight, and that of the sources where I am lifting facts from as fast as I can grab them, all go into this work. I feel myself to be somewhat of an editor, quilting together pieces of intuition and data in ways that attempt to unify these perspectives. The essays that follow seek to look at ways in which nature follows the quiet, yielding tenets of the Tao; reciprocally, the Tao Te Ching will be shown to accurately reflect the …

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Daughter Cells Of Saccharomyces Cerevisiae From Old Mothers Display A Reduced Life Span, Nicanor Austriaco, Brian K. Kennedy, Leonard Guarente Dec 1994

Daughter Cells Of Saccharomyces Cerevisiae From Old Mothers Display A Reduced Life Span, Nicanor Austriaco, Brian K. Kennedy, Leonard Guarente

Biology Faculty Publications

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose …

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Denitrification, Nutrient Regeneration And Carbon Mineralization In Sediments Of Galveston Bay, Texas, Usa, Andrew R. Zimmerman, Ronald Benner Nov 1994

Denitrification, Nutrient Regeneration And Carbon Mineralization In Sediments Of Galveston Bay, Texas, Usa, Andrew R. Zimmerman, Ronald Benner

Faculty Publications

Rates of benthic denitrification, oxygen consumption and nutrient regeneration were measured during winter, spring and summer in Galveston Bay (Texas, USA) sediments. Denitrification ranged from 0 to 47 µmol N2 m-2 h-1 with maximal rates generally occurring in the summer and the upper estuary. Oxygen consumption rates ranged from 38 µmol O2 m-2 h-1 in the winter to 353 µmol O2 m-2 h-1 in the summer and were correlated with denitrification rates. Variations in bay water temperature accounted for 52 % of the variability associated with denitrification rates whereas only 28% …

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