Life Sciences Commons^™

Oxygen Limitation And Tissue Metabolic Potential Of The African Fish Barbus Neumayeri: Roles Of Native Habitat And Acclimatization, Bernard Rees

Biological Sciences Faculty Publications

Oxygen availability in aquatic habitats is a major environmental factor influencing the ecology, behaviour, and physiology of fishes. This study evaluates the contribution of source population and hypoxic acclimatization of the African fish, Barbus neumayeri, in determining growth and tissue metabolic enzyme activities. Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO₂ L^-1) and Inlet Stream West (annual average DO 5.58 mgO₂ L^-1) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to …

Biosynthesis Of Cyanobacterial Phycobiliproteins In Escherichia Coli: Chromophorylation Efficiency And Specificity Of All Bilin Lyases From Synechococcus Sp. Strain Pcc 7002, Wendy M. Schluchter

Biological Sciences Faculty Publications

No abstract provided.

Effects Of Modified Phycobilin Biosynthesis In The Cyanobacterium Synechococcus Sp. Strain Pcc 7002, Wendy M. Schluchter

Biological Sciences Faculty Publications

No abstract provided.

Attachment Of Non-Cognate Chromophores To Cpca Of Synechocystis Sp. Strain Pcc 6803 Expressed In E. Coli, Wendy M. Schluchter

Biological Sciences Faculty Publications

No abstract provided.

Geographic Variation In The Effects Of Heat Exposure On Maximum Sprint Speed And Hsp70 Abundance In Populations Of The Western Fence Lizard, Scelopolus Occidentalis, D M. Mcmillan, D J. Irschick, Bernard B. Rees

Biological Sciences Faculty Publications

We examined whether western fence lizards Sceloporus occidentalis

occurring in thermally divergent environments display differential

responses to high temperature in locomotor performance

and heat-shock protein (Hsp) expression. We measured

maximum sprint speed in S. occidentalis from four populations

at paired latitudes and elevations before and after exposure to

an experimental heat treatment and then quantified hind-limb

muscle Hsp70 expression. Lizards collected from northern or

high-elevation collection sites suffered a greater reduction in

sprint speed after heat exposure than lizards collected from

southern or low-elevation sites. In addition, lizards from northern

collection sites also exhibited an increase in Hsp70 expression

after …

Oxygen Limitation And Tissue Metabolic Potential Of The African Fish Barbus Neumayeri: Roles Of Native Habitat And Acclimatization, Martinez M. L, Raynard E. L, Bernard B. Rees, Chapman L. J

Biological Sciences Faculty Publications

Background: Oxygen availability in aquatic habitats is a major environmental factor influencing the ecology, behaviour, and physiology of fishes. This study evaluates the contribution of source population and hypoxic acclimatization of the African fish, Barbus neumayeri, in determining growth and tissue metabolic enzyme activities. Individuals were collected from two sites differing dramatically in concentration of dissolved oxygen (DO), Rwembaita Swamp (annual average DO 1.35 mgO2 L-1) and Inlet Stream West (annual average DO 5.58 mgO2 L-1) in Kibale National Park, Uganda, and reciprocally transplanted using a cage experiment in the field, allowing us to maintain individuals under natural conditions of …

Exercise-And Hypoxia-Induced Anaerobic Metabolism And Recovery: A Student Laboratory Exercise Using Teleost Fish, Bernard Rees

Biological Sciences Faculty Publications

Anaerobic metabolism is recruitedin vertebrates under conditions of intense exercise or lowered environmental oxygen availability (hypoxia), typically resulting in the accumulation of lactate in blood and tissues. Lactate will be cleared over time after the reoxygenation of tissues, eventually returning to control levels. Here, we present a laboratory exercise developed as part of an upper-level vertebrate physiology class that demonstrates the effects of exercise and hypoxia exposure on blood lactate in fish and the subsequent decrease in lactate during recovery. Typically, the results obtained by students demonstrate that both treatments cause significant increases in blood lactate concentrations (two to three …

Optimality In A Partitioned Task Performed By Social Insects, Jerome J. Howard

Biological Sciences Faculty Publications

Biologists have long been aware that adaptations should not be analysed in isolation from the function of the whole organism. Here, we address the equivalent issue at the scale of a social insect colony: the optimality of component behaviours in a partitioned sequence of tasks. In colonies of Atta colombica, a leaf-cutting ant, harvested leaf tissue is passed from foragers to nest workers that distribute, clean, shred and implant the tissue in fungal gardens. In four laboratory colonies of A. colombica, we found that the highest colony-wide rate of leaf tissue processing in the nest was achieved when leaf fragment …

Vertebrate Osmoregulation: A Student Laboratory Exercise Using Teleost Fish, Bernard Rees

Biological Sciences Faculty Publications

Anaerobic metabolism is recruited in vertebrates under conditions of intense exercise or lowered environmental oxygen availability (hypoxia), typically resulting in the accumulation of lactate in blood and tissues. Lactate will be cleared over time after the reoxygenation of tissues, eventually returning to control levels. Here, we present a laboratory exercise developed as part of an upper-level vertebrate physiology class that demonstrates the effects of exercise and hypoxia exposure on blood lactate in fish and the subsequent decrease in lactate during recovery. Typically, the results obtained by students demonstrate that both treatments cause significant increases in blood lactate concentrations (two to …

Fundulus As The Premier Teleost Model In Environmental Biology: Opportunities For New Insights Using Genomics, Bernard Rees

Biological Sciences Faculty Publications

A strong foundation of basic and applied research documents that the estuarine fish Fundulus heteroclitus and related species are unique laboratory and field models for understanding how individuals and populations interact with their environment. In this paper we summarize an extensive body of work examining the adaptive responses of Fundulus species to environmental conditions, and describe how this research has contributed importantly to our understanding of physiology, gene regulation, toxicology, and ecological and evolutionary genetics of teleosts and other vertebrates. These explorations have reached a critical juncture at which advancement is hindered by the lack of genomic resources for these …

Effects Of Long-Term Hypoxia On Enzymes Of Carbohydrate Metabolism In The Gulf Killifish, Fundulus Grandis, Bernard Rees

Biological Sciences Faculty Publications

The goal of the current study was to generate a comprehensive, multi-tissue perspective of the effects of chronic hypoxic exposure on carbohydrate metabolism in the Gulf killifish Fundulus grandis. Fish were held at approximately 1.3 mg l(-1) dissolved oxygen (approximately 3.6 kPa) for 4 weeks, after which maximal activities were measured for all glycolytic enzymes in four tissues (white skeletal muscle, liver, heart and brain), as well as for enzymes of glycogen metabolism (in muscle and liver) and gluconeogenesis (in liver). The specific activities of enzymes of glycolysis and glycogen metabolism were strongly suppressed by hypoxia in white skeletal muscle, …

Effects Of Long-Term Hypoxia On Enzymes Of Carbohydrate Metabolism In The Gulf Killifish, Fundulus Grandis, M L. Manning, C A. Landry, R D. Boehm, S Manning, A O. Cheek, Bernard B. Rees

Biological Sciences Faculty Publications

The goal of the current study was to generate a comprehensive, multi-tissue perspective of the effects of chronic hypoxic exposure on carbohydrate metabolism in the Gulf killifish Fundulus grandis. Fish were held at approximately 1.3·mg·l–1 dissolved oxygen (~3.6·kPa) for 4·weeks, after which maximal activities were measured for all glycolytic enzymes in four tissues (white skeletal muscle, liver, heart and brain), as well as for enzymes of glycogen metabolism (in muscle and liver) and gluconeogenesis (in liver). The specific activities of enzymes of glycolysis and glycogen metabolism were strongly suppressed by hypoxia in white skeletal muscle, which may reflect decreased energy …

Structure And Sequence Conservation Of A Putative Hypoxia Responsive Element In The Lactate Dehydrogenase-B Gene Of Fundulus, Bernard B. Rees, John A.L. Bowman, P M. Schulte

Biological Sciences Faculty Publications

No abstract provided.

An Evaluation Of Submersed Aquatic Vegetation Transplanting Methods For Lake Pontchartrain Restoration, Donald Anthony Rodrigue Jr.

University of New Orleans Theses and Dissertations

The general goals of this study were to evaluate transplant methods for Lake Pontchartrain submersed aquatic vegetation (SAV) restoration, and to compare survival and expansion of transplanted SAV among four sites. Two experiments were conducted from summer 2000 through spring 2001 at two north shore and two south shore sites in Lake Pontchartrain. Experiment 1 involved testing the effects of transplanting with matting, staples, exclosures, and interspecific interaction on survival and expansion of Ruppia maritima and Vallisneria americana transplants in Lake Pontchartrain. Experiment 2 involved testing the effects of transplanting with matting, staples, and plugs on Ruppia survival and expansion. …

Molecular Mechanisms Of Metabolic Arrest: Life In Limbo (Book Review), Bernard Rees

Biological Sciences Faculty Publications

No abstract provided.

Assembly Of Reca-Like Recombinases: Distinct Roles For Mediator Proteins In Mitosis And Meiosis, Stephen L. Gasior

Biological Sciences Faculty Publications

Members of the RecA family of recombinases from bacteriophage T4, Escherichia coli, yeast, and higher eukaryotes function in recombination as higher-order oligomers assembled on tracts of single-strand DNA (ssDNA). Biochemical studies have shown that assembly of recombinase involves accessory factors. These studies have identified a class of proteins, called recombination mediator proteins, that act by promoting assembly of recombinase on ssDNA tracts that are bound by ssDNA-binding protein (ssb). In the absence of mediators, ssb inhibits recombination reactions by competing with recombinase for DNA-binding sites. Here we briefly review mediated recombinase assembly and present results of new in vivo experiments. …

Acclimation To Hypoxia Increases Survival Time Of Zebrafish, Danio Rerio, During Lethal Hypoxia, Bernard B. Rees, F Sudradjat, J W. Love

Biological Sciences Faculty Publications

Survivorship of zebrafish, Danio rerio, was measured during lethal hypoxic stress after pretreatment in water at either ambient oxygen or at a lowered, but nonlethal, level of oxygen. Acclimation to nonlethal hypoxia (pO2 @ 15 Torr; ca. 10% air-saturation) for 48 hr significantly extended survival time during more severe hypoxia (pO2 @ 8 Torr; ca. 5% air-saturation) compared to survival of individuals with no prior hypoxic exposure. The magnitude of the acclimation effect depended upon the sex of the fish: hypoxia pretreatment increased the survival times of males by a factor of approximately 9 and that of females by a …

Tid1/Rdh54 Promotes Colocalization Of Rad51 And Dmc1 During Meiotic Recombination, Stephen L. Gasior

Biological Sciences Faculty Publications

Two RecA homologs, Rad51 and Dmc1, assemble as cytologically visible complexes (foci) at the same sites on meiotic chromosomes. Time course analysis confirms that co-foci appear and disappear as the single predominant form. A large fraction of co-foci are eliminated in a red1 mutant, which is expected as a characteristic of the interhomolog-specific recombination pathway. Previous studies suggested that normal Dmc1 loading depends on Rad51. We show here that a mutation in TID1/RDH54, encoding a RAD54 homolog, reduces Rad51-Dmc1 colocalization relative to WT. A rad54 mutation, in contrast, has relatively little effect on RecA homolog foci except when strains also …

Rad52 Associates With Rpa And Functions With Rad55 And Rad57 To Assemble Meiotic Recombination Complexes, Stephen L. Gasior

Biological Sciences Faculty Publications

We show that the Saccharomyces cerevisiae recombination protein Rad52 and the single-strand DNA-binding protein RPA assemble into cytologically detectable subnuclear complexes (foci) during meiotic recombination. Immunostaining shows extensive colocalization of Rad52 and RPA and more limited colocalization of Rad52 with the strand exchange protein Rad51. Rad52 and RPA foci are distinct from those formed by Rad51, and its meiosis-specific relative Dmc1, in that they are also detected in meiosis during replication. In addition, RPA foci are observed during mitotic S phase. Double-strand breaks (DSBs) promote formation of RPA, Rad52, and Rad51 foci. Mutants that lack Spo11, a protein required for …

Do Biochemical Exaptations Link Evolution Of Defense And Pollination Systems? Historical Hypotheses And Experimental Tests With Dalechampia Vines, Jerome J. Howard

Biological Sciences Faculty Publications

Mapping resin secretion and pollination ecology onto the estimated phylogeny of species of the euphorb vine Dalechampia generated two historical hypotheses: resin rewards offered to pollinators by Dalechampia flowers evolved by minor modification of a preexisting, resin-based, floral defense system, and resin defense of leaves in advanced species evolved by modification of the preexisting resin-reward system. From these hypotheses, we derived two predictions: floral reward resins are chemically similar to putative floral defense resins and exhibit antiherbivore activities, and foliar resins are chemically similar to reward resins and also exhibit antiherbivore activities. We tested these predictions by chemical analyses and …

Biochemical Correlates Of Estivation Tolerance In The Mountainsnail Oreohelix (Pulmonata: Oreohelicidae), Bernard Rees

Biological Sciences Faculty Publications

Biochemical changes occurring over 7 months of estivation were studied in two species of land snail, Oreohelix strigosa (Gould) and 0. subrudis (Reeve), to determine whether differential mortality during estivation is related to different energetic strategies. Laboratory- maintained snails, which were fed ad libitum prior to es- tivation, were compared with snails collected from the field and induced to estivate without augmenting their energy reserves. In all groups, polysaccharide was catab- olized early in estivation, and protein was the primary metabolic substrate after polysaccharide reserves were de- pleted. Lipid was catabolized at a low rate throughout estivation. Rates of catabolism …

Intracellular Ph Decreases During Entry Into Estivation In The Land Snail Oreohelix, Bernard Rees

Biological Sciences Faculty Publications

No abstract provided.

Heat Dissipation, Gas Exchange And Acid-Basic Balance In The Land Snail Oreohelix During Short-Term Estivation, Bernard Rees

Biological Sciences Faculty Publications

Within 4 days following entry into estivation, heat dissipation and oxygen consumption by the land snail Oreohelix spp. decreased by 83 % compared to standard non-estivating rates. During both non-estivating and estivating conditions, the quantity of heat dissipated per mole of O2 consumed was indicative of a completely aerobic metabolism. This calorimetric-respirometric (C/R) ratio was — 461 ± 12 kJ moP102 (S.E.M., N=5) under standard non-estivating conditions and — 464±26kJmol~1O2 (7V=4) during estivation. Respiratory exchange ratios reflected a primary dependence upon carbohydrate as a metabolic substrate during both states. Carbon dioxide retention occurred during the first 36h of estivation, resulting …

Kinetic Properties Of Hexokinase Under Near-Physiological Conditions: Relation To Metabolic Arrest In Artemia Embryos During Anoxia, Bernard Rees

Biological Sciences Faculty Publications

Previous analyses of glycolytic metabolites in Artemia embryos indicate that an acute inhibition of glucose phosphorylation occurs during pHi-mediated metabolic arrest under anoxia. We describe here kinetic features of hexokinase purified from brine shrimp embryos in an attempt to explain the molecular basis for this inhibition. At saturating concentrations of cosubstrate, ADP is an uncompetitive inhibitor toward glucose and a partial noncompetitive inhibitor toward ATP (Kis = 0.86 mM, Kii = 1.0 mM, Kid = 1.9 mM). With cosubstrates at subsaturating concentrations, the uncompetitive inhibition versus glucose becomes noncompetitive, while inhibition versus ATP remains partial noncompetitive. The partial noncompetitive inhibition …

Isolation, Growth Characteristics, And Long-Term Storage Of Fungi Cultivated By Attine Ants, Jerome J. Howard

Biological Sciences Faculty Publications

Seven pure-culture strains of fungi cultivated by attine ants (ant-garden fungi) were isolated from locally maintained leaf-cutting ant colonies. An ant-garden fungus strain obtained from an Atta cephalotes colony, when offered to ants of the colony from which the fungus was isolated, was accepted as their own. Young fungus cultures were harvested and incorporated into the fungus garden, and cultures of intermediate age were used to begin a new fungus garden; old cultures were simply harvested. To facilitate further research on this fungus, growth characteristics of the different isolates were studied under a variety of conditions. They grew better at …

Leafcutting And Diet Selection: Relative Influence Of Leaf Chemistry And Physical Features, Jerome J. Howard

Biological Sciences Faculty Publications

The effects of leaf toughness, trichome characteristics, nutrient and water availability, and secondary chemistry on diet selection by the leafcutting ant Atta cephalotes were determined using individuals of 49 woody plant species from a tropical deciduous forest in Costa Rica. The palatability of plants was measured by presenting whole leaves to leafcutting ant foragers on trails and counting the number of pieces cut from leaves. The effectiveness of physical barriers to leaf cutting was evaluated by measuring the speed with which ants were able to cut leaves of varying toughness, trichome densities, and trichome lengths. Plant secondary chemistry was highly …

Leafcutting Ant Diet Selection: The Role Of Nutrients, Water, And Secondary Chemistry, Jerome J. Howard

Biological Sciences Faculty Publications

The relationship of plant secondary chemistry, water content, and nutrient content to the palatability of leaves to the leafcutting ant Atta cephalotes was determined in a study of individuals from 50 woody plant species in tropical dry forest of Costa Rica. The study took place during the yearly period of maximum leaf harvest, in the early rainy season. The palatability of plants was determined by presenting leaf disks to ants on active foraging trails of three ant colonies. The distribution of several classes of polar secondary compounds in leaf samples was determined using chemical spot tests, and that of ant- …

Thermal Dependence Of Maximal Ca2+-Activated Force In Skinned Muscle Fibres Of The Toad Bufo Marinus Acclimated At Different Temperatures, Bernard Rees

Biological Sciences Faculty Publications

Mechanically skinned muscle fibres from the twitch region of the iliofibularis muscle of cool- (16 +/- 1 degree C) and warm- (32 +/- 1 degree C) acclimated cane toads (Bufo marinus) were activated maximally by Ca2+ in solutions of different pH and at different temperatures (approx. 1-35 degrees C). Acclimation of up to 12 weeks at 16 degrees C and up to 8 weeks at 32 degrees C did not modify the marked thermal dependence of isometric force in the skeletal muscle fibres of the cane toad. The prominent decline of maximum Ca2+-activated force at lower temperatures, a property which …

Repellent Activity Of The Secretion Of Edessa Rufomarginata, A Neotropical Pentamid, Jerome J. Howard

Biological Sciences Faculty Publications

No abstract provided.

Chemical Leaf Repellency To An Attine Ant: Seasonal Distribution Among Potential Host Plant Species, Jerome J. Howard

Biological Sciences Faculty Publications

The chemical repellency of leaves to the leaf-cutting, fungus-growing ant Atta cephalotes was surveyed for 42 plant species randomly selected from the dry forest of Santa Rosa National Park, Guanacaste, Costa Rica. The sample represents about one-sixth of the potential host plant species available to the ants in the secondary, semideciduous forest at Santa Rosa. Repellencies of leaf extracts were measured by bioassay. A laboratory colony of A. cephalotes collected from Santa Rosa was used. Three-quarters of the species exhibited significantly repellent nonpolar (lipid-soluble) extractables (e.g., terpenoids, steroids, and waxes), and half of the species exhibited repellent polar extractables (e.g., …