Life Sciences Commons^™

Phytoplankton Composition In A Borrow Pit Lake In Virginia, Seba B. Sheavly, Harold G. Marshall

Biological Sciences Faculty Publications

The phytoplankton assemblages in Lake Trashmore, Virginia, a borrow pit, were dominated by centric diatoms and cyanobacteria, with seasonal pulses of cryptomonads, euglenoids, and chlorophyceans. Ninety species were identified and their abundance levels noted for a 12-month period.

Community Responses To Variable Predation: Field Studies With Sunfish And Freshwater Macroinvertebrates, Mark J. Butler Iv

Biological Sciences Faculty Publications

The impact of variable predation by bluegill sunfish on macroinvertebrate prey in a North Florida lake is examined. Variable predation may occur in many systems and may contribute substantially to the spatial heterogeneity, temporal inconstancy and species composition of prey communities.

Patchy, temporally variable predation characterized middepth and deep lake habitats, whereas in the shallow zone predation was relatively constant and homogeneous. Predation varied significantly every 2-4 wk in the mid-depth zone, but varied little between consecutive weeks or days. Caging experiments revealed that variable predation altered prey community composition and increased the mean size and size range of some …

Are Artificial "Witham" Surface Collectors Adequate Indicators Of Caribbean Spiny Lobster, Panulirus Argus, Recruitment?, Mark J. Butler Iv, William F. Herrnkind

Biological Sciences Faculty Publications

Understanding the local dynamics of Caribbean spiny lobster (Panulirus argus) postlarval influx, settlement, and recruitment may be essential for the responsible management of this important and heavily exploited resource. Most lobster recruitment research programs in the Caribbean employ derivations of the "Witham"-type surface collector to monitor postlarval (puerulus) lobster influx. However, the relevance of data obtained from surface collectors with respect to the estimation of actual puerulus influx, settlement, or recruitment to subsequent benthic juvenile stages remains untested. We investigated that relevance on regional (i.e., tens of kilometers) and local (i.e., tens of meters) scales by examining the …

Probing The Alpha-Sarcin Region Of Escherichia-Coli 23s Rrna With A Cdna Oligomer, Gary A. White, Ted Wood, Walter E. Hill

Biological Sciences Faculty Publications

The cause of 50S ribosomal subunit collapse reportedly triggered by hybridization of a 14-base cDNA probe to the alpha-sarcin region of 23S rRNA was investigated by physical measurement of probe-subunit complexes in varying buffer conditions. The results reported here show that this probe was unable to hybridize to its target site in the intact 50S subunit and the physical characteristics of 50S subunits remained unchanged in its presence. Subunit collapse was induced in buffer containing 20mM Tris-HCl (pH 7.5), 600 mM NH4Cl, 1 mM MgCl2, 1 mM DTT, and 0.1 mM EDTA in the absence of probe. The probe bound …

Crystallization Of Trimeric Recombinant Human Tumor Necrosis Factor (Cachectin), M. J. Eck, B. Beutler, G. Kuo, J. P. Merryweather, S. R. Sprang

Biological Sciences Faculty Publications

Crystals of tumor necrosis factor (TNF) have been obtained in two forms. Rhombohedral crystals grow in 1.8 to 2.0 M ammonium sulfite, pH 7.8 at 21°C, and tetragonal crystals grow in 2.6 M magnesium sulfate, pH 5.5 at 25°C. Analysis of TNF by isoelectric focusing under native and denaturing conditions indicates that TNF molecules exist as trimers in solution. The rhombohedral cachectin crystals belong to space group R3 and have unit cell constants a = b = c = 47.65 Å and α = β = γ = 88.1°. Density determinations and the space group indicate that the unit cell …

Comparative Analysis Of The Effects Of Visual And Auditory Stimuli On Avian Mobbing Behavior, C. Ray Chandler, Robert K. Rose

Biological Sciences Faculty Publications

Both visual and auditory stimuli elicit avian mobbing behavior, but there is little comparative information on their isolated and additive effects. Using three combinations of two experimental stimuli (mount and tape of an Eastern Screech-Owl, Otus asio) we tested the effects of stimuli on the frequency, intensity, and duration of avian mobbing behavior. Of 169 mount-only trials, only 11 (6.5%) were successful in attracting birds. Tape-only (n = 169) and mount-and-tape (n = 170) were equally successful in attracting birds (approximately 85% of all trials), but mount-and-tape trials were more likely to initiate mobbing behavior. Birds responding …

Dna Probe Method For The Detection Of Specific Microorganisms In The Soil Bacterial Community, William Holben, Janet K. Jansson, Barry K. Chelm, James M. Tiedje

Biological Sciences Faculty Publications

We developed a protocol which yields purified bacterial DNA from the soil bacterial community. The bacteria were first dispersed and separated from soil particles in the presence of polyvinylpolypyrrolidone, which removes humic acid contaminants by adsorption to this insoluble polymer. The soil bacteria were then collected by centrifugation and lysed by using a comprehensive protocol designed to maximize disruption of the various types of bacteria present. Total bacterial DNA was purified from the cell lysate and remaining soil contaminants by using equilibrium density gradients. The isolated DNA was essentially pure as determined by UV spectral analysis, was at least 48 …

Identification Of Defined Sequences In Domain V Of E.Coli 23s Rrna In The 50s Subunit Accessible For Hybridization With Complementary Oligodeoxyribonucleotides, Richard T. Marconi, Walter E. Hill

Biological Sciences Faculty Publications

The accessibility of specific sequences in domain V of E. coli 23s rRNA in the 50S subunit to complementary oligodeoxyribonucleotides (cDNA) has been investigated. The apparent percentage of subunits engaged in complex formation was determined by incubation of radiolabeled cDNA probe with 50S subunits, followed by nitrocellulose membrane filtration of the reaction mixtures and measurement of the bound radiolabeled cDNA probes by liquid scintillation counting of the filters. The site(s) of hybridization were determined by digestion of the RNA in the RNA/DNA heteroduplex by RNase H. The results of this study indicated that single-stranded sequences, 2058-2062, 2448-2454, 2467-2483, and 2497-2505 …

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 …

Host Selection In Subterranean Termites: Factors Affecting Choice (Isoptera: Rhinotermitidae), Deborah Ann Waller

Biological Sciences Faculty Publications

The effects of block size and species on preference were examined for the subterranean termite Reticulitermes sp. (Rhinotermitidae) in choice and no-choice tests. Termites significantly preferred Douglas fir over Ponderosa pine and red oak, irrespective of block size. The less-preferred woods were eaten in large amounts in no-choice tests, and all three woods appeared to be favorable for the termites and their gut protozoans. In single species tests, termites ate significantly more from larger blocks of Douglas fir, but ate similar amounts from large and small blocks of Ponderosa Pine and red oak. These results suggest that several factors can …

The Effects Of Siltation On Recruitment Of Spiny Lobsters, Panulirus Argus, William F. Herrnkind, Mark J. Butler, Richard A. Tankersley

Biological Sciences Faculty Publications

Fewer juvenile pinry lobsters were found in areas of the Florida Keys where their primary habitat was heavily silted as compared with similar, less silted habitat. Several hypotheses explaining this relationship were tested, and the time-to-metamorphosis was compared for settling pueruli within silted and nonsilted algae stands. Limited postlarval settlement and avoidance of silted algal habitats by juveniles, probably accounts for the paucity of young lobsters in heavily silted sites. In addition, although juvenile lobsters are nonselective predators, lower prey availability in silted algae probably promotes transciency which, in turn, causes increased mortality by predation while juveniles are exposed.

Evaluation Of Possible Reproductively Mediated Character Displacement In The Crayfishes, Orconectes Rusticus And O. Sanbornii, Mark J. Butler Iv

Biological Sciences Faculty Publications

Orconectes rusticus is replacing several species of crayfishes in north-central and northeastern North America, including O. sanbornii in Ohio. Recent evidence suggests that the species replacements may be driven by asymmetrical reproductive success favoring O. rusticus. Nonetheless, some sympatric associations appear locally persistent. Because crayfish demonstrate size assortative mating and there is a disparity in the sizes of the species, further divergence in the sizes of the species in sympatry could enhance reproductive isolation, ultimately providing a mechanism for character displacement. To test this hypothesis the size differentials between crayfish collected from allopatric and sympatric populations in east-central Ohio …

Use Of Woody Vegetation By Beavers In Southeastern Virginia, John L. Echternach, Robert K. Rose

Biological Sciences Faculty Publications

Nonbreeding and sometimes transient beavers, Castor canadensis, cut a variety of woody plants throughout the year during a 15-month study at three sites in southeastern Virginia. Ten species of trees were cut in proportions greater than would be expected according to their availabilities. Beavers heavily used viburnum, alder, ironwood, bayberry, tulip poplar, and dogwood. Winter food caches were constructed but were only lightly used.

Nearctic Avian Migrants In The Neotropics By J. H. Rappole; E. S. Morton; T. E. Lovejoy, Jr.; J. L. Ruos, Richard L. Hutto

Biological Sciences Faculty Publications

No abstract provided.

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- …

A Description Of Mixed-Species Insectivorous Bird Flocks In Western Mexico, Richard L. Hutto

Biological Sciences Faculty Publications

Insectivorous bird flocks were observed in all types of forested habitats during the nonbreeding season in western Mexico. The species composition of flocks changed markedly and predictably among five categories of habitat type. The average number of species per flock in lowland habitats was 4.7, while a mean of 18.6 species participated in highland flocks, ranking the latter among the most species-rich flocks in the world. The mean proportion of the local insectivorous species that participated in mixed-species flocks was significantly greater in the highlands (61.3%) than in the lowlands (24.6%). About half of the flock participants in both undisturbed …

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 …

Heterozygosity And Oxygen-Consumption Rate As Predictors Of Growth And Developmental Rate In Rainbow-Trout, Roy G. Danzmann, Moira M. Ferguson, Fred W. Allendorf

Biological Sciences Faculty Publications

No abstract provided.

Characterization Of Protein-I From Serum-Sensitive And Serum-Resistance Transformants Of Neisseria-Gonorrhoeae, Ralph C. Judd, Milton Tam, Keith Joiner

Biological Sciences Faculty Publications

No abstract provided.

Distribution And Current Status Of The Threatened Dismal Swamp Southeastern Shrew, Sorex Longirostris Fisheri, Robert K. Rose, Roger K. Everton, Thomas M. Padgett

Biological Sciences Faculty Publications

The Dismal Swamp southeastern shrew, Sorex longirostris fisheri, was given "Threatened" status by the U.S. Fish and Wildlife Service in 1986 because of its limited distribution and the potential threat of interbreeding with the nearby upland subspecies, Sorex l. longirostris. Known from about 20 specimens collected before 1980 and a few dozen taken since then, "fisheri" seems to have morphologically diverged from the smaller upland "longirostris" in association with the development of the Dismal Swamp. The detection of southeastern shrews that are intermediate in size between the two subspecies, coupled with the location of these collection sites on …

The Identification Of The Threatened Southeastern Shrew Using Multivariate Statistical Techniques, Thomas M. Padgett, Roger K. Everton, Robert K. Rose

Biological Sciences Faculty Publications

The threatened subspecies of the southeastern shrew, Sorex longirostris fisheri, is endemic to the Great Dismal Swamp of southeastern Virginia. Previous studies based on discriminant analysis of external measurements determined that intergrades with the upland form, Sorex l. longirostris, exist along the periphery of the Swamp. To better discriminate among these populations, a study of cranial morphology was initiated. Fifteen cranial measurements were taken, using 59 specimens of Sorex collected previously form southeastern Virginia, including the Dismal Swamp. Both Principal Component and Cluster Analyses revealed no significant cranial variation or morphometric patterns within the specimens examined, but a …

Evidence For N-Terminal Exposure Of The Protein Ia Subclass Of Neisseria-Gonorrhoeae Protein-I, Ralph C. Judd

Biological Sciences Faculty Publications

The JS3 and FA638 strains of Neisseria gonorrhoeae bear a protein IA subclass of protein I (P.I). The purified P.Is of surface-labeled strains JS3 and FA638 were cleaved with the N-terminal degradation enzyme leucine amino peptidase (LAP), and the resultant fragments were separated in sodium dodecyl sulfate-polyacrylamide gels. Autoradiography demonstrated that the surface radiolabel was absent in a LAP-generated P.I peptide that was about 1,900 daltons lower in apparent molecular mass than the native P.I in both strains. Moreover, the 4G5 monoclonal epitope, known to be located on the surface of the organism, was also absent in the LAP-generated P.I …

A Fixed-Radius Point Count Method For Nonbreeding And Breeding-Season Use, Richard L. Hutto, Sandra M. Pletschet, Paul Hendricks

Biological Sciences Faculty Publications

We provide a detailed description of a fixed-radius point count method that carries fewer assumptions than most of the currently popular methods of estimating bird density and that can be used during both the nonbreeding and breeding seasons. The method results in three indices of bird abundance, any of which can be used to test for differences in community composition among sites, or for differences in the abundance of a given bird species among sites. These indices are (1) the mean number of detections within 25 m of the observer, (2) the frequency of detections within 25 m of the …

Late Prehistoric And Protohistoric Large Mammal Zoogeography Of Virginia, Robert K. Rose

Biological Sciences Faculty Publications

Evidence derived from18late prehistoric (middle and late Woodland Period) archeological sites, from several early historical accounts, and from the current understanding of the distribution of Virginia mammals indicates that the large mammal fauna of the Commonwealth has not changed substantially within the past 4,000 yrs. Some species (e.g., bison, elk, timber wolf, and mountain lion) have been extirpated since the settlement of Virginia by Europeans; some previously extirpated species (e.g., porcupine, coyote, and beaver) have been naturally or artificially reintroduced during the historical period, and others (e.g., woodchuck and red fox) probably have expanded their distributions as a result of …

Reproductive Strategies Of Meadow Voles, Hispid Cotton Rats, And Eastern Harvest Mice In Virginia, Robert K. Rose

Biological Sciences Faculty Publications

Patterns of reproduction in small mammals in Virginia were examined by autopsying samples of meadow voles (Microtus pennsylvanicus) collected for 23 months near Charlottesville, of hispid cotton rats (Sigmodon hispidus) collected for 14 months in Portsmouth, and by evaluating live-caught eastern harvest mice (Reithrodontomys humulis) trapped for 15 months in Suffolk and for 12 months in Chesapeake. The meadow vole, a microtine rodent with a north temperate and sub-arctic distribution throughout North America, suspended breeding during the winter of peak density but not of declining density. High metabolic rates and other adaptations for winter …

Quantitation And Identification Of Organic N-Chloramines Formed In Stomach Fluid On Ingestion Of Aqueous Hypochlorite, Frank E. Scully Jr., Katherine Mazina, Daniel E. Sonenshine, Frederick Kopfler

Biological Sciences Faculty Publications

The chemical reactions that hypochlorite undergoes in the body when chlorinated water is ingested have received very little attention. Because amino nitrogen compounds are important components of the average diet, the reactions of hypochlorite with amino compounds in the stomach were investigated. Stomach fluid was recovered from Sprague-Dawley rats that had been fasted for 48 hr and administered 4 mL deionized water. The chlorine demand of the stomach fluid was determined. An average volume-independent demand of 2.7 mg chlorine was measured. At doses below 40 mg/L chlorine reducing reactions appeared to account for reduction of all oxidizing species within 15 …

Factors Regulating Settlement And Microhabitat Use By Spiny Lobsters Panulirus Argus, William F. Herrnkind, Mark J. Butler Iv

Biological Sciences Faculty Publications

Clumps of highly-branched red algae Laurencia spp. serve as important settling habitat for postlarval spiny lobsters Panulirus argus and as residence for early benthic-stage juveniles. Given choice between the 2 most abundant macrophytes in Florida Bay, Laurencia spp. and the seagrass Thalassia testudinum, postlarval and juvenile lobsters chose Laurencia spp. Postlarvae apparently use intricate algal architecture as a cue for settlement, whereas juveniles use both architecture and food abundance in selecting habitat. In tethering experiments, predation on juvenile lobsters was very high on open sand, much reduced in algal clumps and seagrass, and lowest in dense algal meadows. Predation …

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

Biological Sciences Faculty Publications

No abstract provided.

Going To Extremes: Why Do Sanderlings Migrate To The Neotropics?, J. P. Myers, John L. Maron, Michel Sallaberry A.

Biological Sciences Faculty Publications

Sanderlings (Calidris alba) breed within a small latitudinal range in the arctic while spreading in winter virtually throughout temperate and tropical marine beaches of the world. This paper examines spatial variation in Sanderlings nonbreeding density across the New World, documents annual cycle differences between populations wintering in California and those wintering in Peru and Chile, and then explores demographic and ecological factors underlying Sanderlings migration to different wintering grounds. Densities during the nonbreeding season are higher on the Pacific coast than on the Atlantic at all censused latitudes in the New World, and reach a peak in southwestern …

Seasonal Changes In Feeding Success, Activity Patterns, And Weights Of Nonbreeding Sanderlings (Calidris Alba), John L. Maron, J. P. Myers

Biological Sciences Faculty Publications

Seasonal changes in Sanderling (Calidris alba) feeding success, time budgets, and weights were followed throughout the nonbreeding season at Bodega Bay, California. Sanderlings spent more time roosting in fall than in winter, and in fall adults spent more time roosting than juveniles. Sanderling prey capture rates were high in fall and spring and declined through winter. Sanderling weights paralleled seasonal changes in feeding success and activity patterns: birds were heaviest in fall and spring and lightest in winter. These results reflect lowered food availability in winter and imply that birds may have difficulty balancing their energy budgets during …