Life Sciences Commons^™

Decomposition Of Senescent Blades Of The Seagrass Halodule Wrightii In A Subtropical Lagoon, Stephen Opsahl, Ronald Benner

Faculty Publications

Senescent blades from the seagrass Halodule wrightii Aschers were suspended in the water column of Laguna Madre (Texas, USA) for a period of 419 d, representing the longest seagrass decomposition study to date. The initial stage of decomposition was characterized by a rapid loss of organic matter (36 % in 24 d) attributed to leaching. A total of 76 % of the organic matter from seagrass tissues was lost by the end of the decomposition period. Of the major bulk constituents measured, neutral sugars were most abundant and accounted for 23 % of the ash-free dry wt of the initial …

Endocytosis In Plant Protoplasts: Visualization And Quantitation Of Fluid-Phase Endocytosis Using Silver-Enhanced Bovine Serum Albumin-Gold [Abstract], Marco A. Villanueva, Josephine Taylor, Lawrence R. Griffing

Faculty Publications

No abstract provided.

Denitrification And Oxygen Consumption In Sediments Of Two South Texas Estuaries, Won Bae Yoon, Ronald Benner

Faculty Publications

Spatial and temporal variations in rates of denitrification and oxygen consumption were measured in sediments of the Nueces and Guadalupe Estuaries in southern Texas, USA. Denitrification rates varied from 4.0 to 71.1 µmol N₂ m^-2 h^-1 in the Nueces Estuary and from 4.6 to 34.7 µmol N₂ m^-2 h^-1 in the Guadalupe Estuary. Denitrification accounted for 29 to 80% of total benthic N flux in the study areas. Oxygen consumption rates ranged from 176 to 818 µmol O₂ m^-2 h^-1 in Nueces Estuary and from 208 to 550 µmol O_{2 …}

Bacterial Numbers And Activity, Microalgal Biomass And Productivity, And Meiofaunal Distribution In Sediments Naturally Contaminated With Biogenic Bromophenols, Charles C. Steward, James L. Pinckney, Yvette Piceno, Charles R. Lovell

Faculty Publications

Sediment cores were collected inside and outside of a bed of a bromophenol-producing marine polychaete, Notomastus lobatus, and examined for impact of the bromophenols on sediment microflora and meiofauna around N. lobatus burrows. No significant differences were found between microbial parameters measured inside and outside of the N. lobatus bed. Integrated 6 cm cores taken adjacent to N. lobatus burrows contained 1.2 x 10⁹ bacteria ml^-1. Cell numbers were similar at control sites within the bed, but away from burrows, and not significantly different from cell numbers (1.0 X 10⁹ cells ml^-1) at a …

Enhanced Bacterioplankton Production And Respiration At Intermediate Salinities In The Mississippi River Plume, Gerardo Chin-Leo, Ronald Benner

Faculty Publications

Bacterial abundance and production (thymidine and leucine incorporation) were measured along a salinity gradient from the Mississippi River (0 %₀) to the open waters of the Gulf of Mexico (36 %₀) during July-August 1990 and February 1991. Bacterial production in surface waters was maximal at intermediate salinities (15 to 30 %₀). Nutrient enrichment experiments suggested that bacterial growth near the outflow of the river was C limited whereas bacteria in plume waters of intermediate salinities were P and N limited. Rates of plankton community oxygen demand measured during winter were also maximal at intermediate …

Nuclear Dna Content Variation Within The Rosaceae, E. E. Dickson, K. Arumuganathan, Stephen Kresovich, J. J. Doyle

Faculty Publications

Nuclear DNA content has been estimated using flow cytometry for 17 species and eight cultivars of Malus and for 44 species of 29 other genera within the Rosaceae. Compared to other angiosperms, diploid genome sizes vary little within the family Rosaceae and within the genus Malus. C-values of genera within the subfamilies Spiraeoideae and Rosoideae are among the smallest of flowering plants thus far reported. In general, the Maloideae have the largest diploid genomes of the family, consistent with their higher chromosome numbers and presumed polyploid origin.

Effects Of Tidal Stage And Sun Angles On Intertidal Benthic Microalgal Productivity, James L. Pinckney, R. G. Zingmark

Faculty Publications

Motile benthic diatoms exhibit rhythmic vertical migrations that are influenced by tidal and light cycles. As a consequence of these periodic migrations, corresponding periodicities in benthic microalgal production should occur. Using oxygen microelectrodes, hourly measurements of microalgal production were obtained from subaerially exposed cores collected from low-intertidal muddy sediments in North Inlet estuary, South Carolina, USA Microalgal productivity at low tide was twice that at high tide (mean difference 52 %) and was significantly correlated with diurnal and tidal periodicities (r² = 0.41; p < 0.0001). Production values ranged from 28.0 to 460.5 µmol O₂ mg chl a^-1 h^-1 and maximum rates were achieved during mid-afternoon low …

Dynamics Of Bacterioplankton Abundance And Production In Seagrass Communities Of A Hypersaline Lagoon, Gerardo Chin-Leo, Ronald Benner

Faculty Publications

The significance of bacterioplankton in the flow of carbon and energy and in trophic dynamics of the upper Laguna Madre, Texas (USA), was estimated by measuring bacterioplankton abundance and production over an 18 mo period and over several diel cycles. Bacterioplankton production was estimated from incorporation rates of thymidine (DNA synthesis) and leucine (protein synthesis). These independent inhces of bacterial growth were generally in agreement and yielded nearly identical annual estimates of bacterial production (25.24 g C m^-2 yr^-1 based on thymidine and 25.12 g C m^-2 yr^-1based on leucine). Assuming a 30 % growth …

Fungal Development And Host Cell Responses To The Rust Fungus Puccinia Substriata Var. Indica In Seedling And Mature Leaves Of Susceptible And Resistant Pearl Millet [Abstract], Josephine Taylor, C. W. Mims

Faculty Publications

No abstract provided.

'Eve' In Africa: Human Evolution Meets Molecular Biology, Robert D. Seager

Faculty Publications

Recent advances in the study of human origins have increased our understanding of our ancestors. There have been new, major fossil finds. WT 17000, a 2.5 million-year-old robust Australopithecus found in Kenya (Walker et al. 1986), led to a revision of early hominid phylogeny (Delson 1986; 1987). Existing fossil materials have been reassessed. For example, Tattersall (1986) maintains that at least two unrecog­- nized hominid species (Homo neanderthalensis, H. hei­ delbergensis and possibly H. steinheimensis ) existed be­ tween the times of H . erectus and fully modern H . sapiens.

Adaptive Coloration In Texas Fiddler Crabs (Uca), Carl L. Thurman

Faculty Publications

Five species of fiddler crabs occupy a variety of intertidal niches along the Texas coast. Each Uca is adapted to a specific array of physical factors in the environment. Some aspects of their adaptations are reflected by body color. Interspecific differences in morphological coloration are correlated with camouflage and substrate characteristics. Intraspecific color variation is expressed through neurosecretion-mediated physiological change in cellular pigment distribution. Adaptation to a dark or light colored background reveals different "secondary" chromomotor capabilities for each species. In addition, pigments in melanophores, leucophores and erythrophores exhibit circadian rhythms of dispersion and aggregation.

During a "primary" chromomotor response …

Dietary Protein Deficiency And Mycobacterium Bovis Bcg Affect Interleukin-2 Activity In Experimental Pulmonary Tuberculosis, David N. Mcmurray, C. L. Mintzer, R. A. Bartow, Rebecca D. Parr

Faculty Publications

Inbred strain 2 guinea pigs were vaccinated with Mycobacterium bovis BCG or were left unvaccinated. They were maintained for 6 weeks on defined, isocaloric diets containing either 30% (control animals) or 10% (animals receiving low protein) ovalbumin as the sole protein source. Animals were challenged by the respiratory route with a low dose of virulent M. tuberculosis H37Rv and killed 4 weeks later. Protein-malnourished animals were not protected by previous vaccination with BCG. Lymphocytes isolated from various tissues were tested in vitro for proliferative responses to mitogen (concanavalin A) and antigen (purified protein derivative [PPD]), production of interleukin-2 (IL-2), and …

Ultrastructure Of The Early Stages Of Infection Of Peanut Leaves By The Rust Fungus Puccinia Srachidis [Abstract], C. W. Mims, Josephine Taylor, E. A. Richardson

Faculty Publications

No abstract provided.

Age And Growth Of King Mackerel, Scomberomorus Cavalla, From The Atlantic Coast Of The United States, Mark R. Collins, David J. Schmidt, C. Wayne Waltz, James L. Pinckney

Faculty Publications

Whole sagittae from 683 and sectioned sagittae from 773 "adult" (age> 0 ; 437-1.310 mm FL), and lapilli from 29 larval (2-7 mm SL) and 69 young-of-the-year (79-320 mm FL) king mackerel, were examined. All fish were from waters off the Atlantic coast of the southeastern United States (Cape Canaveral, Florida to Cape Fear. North Carolina). Back-calculated lengths at ages and von Bertalanffy growth equations were calculated from both whole and sectioned sagittae. Ages determined from sectioned sagittae were significantly greater than ages determined from whole sagittae, and the magnitude of the difference increased with age (from sections). Rings on …

Organ-Specific And Development Regulation Of The Nopaline Synthase Promoter In Transgenic Tobacco Plants, Gynheung An, Michael A. Costa, Amitava Mitra, Sam-Bong Ha, László Márton

Faculty Publications

Control regions of the nopaline synthase (nos) gene have been widely used to express foreign genes in plants since the promoter is active in a wide variety of plant tissues. We report here the characteristics of the nos promoter activity in transgenic tobacco (Nicotiana tabacum) plants at various developmental stages. The promoter was highly active in the lower parts of a plant and gradually decreased in the upper parts. This vertical gradient was maintained throughout plant growth until the flowering stage when the overall promoter strength decreased significantly in the vegetative organs. However, in various flower …

Sequence Of The Psba Gene From Wild Type Triazin-Resistant Nicotiana Plumbaginifolia, Anikó Páy, Marvin A. Smith, Ferenc Nagy, László Márton

Faculty Publications

No abstract provided.

Local Ecology And Multiple Mating In A Natural Population Of Drosophila Melanogaster, R. W. Marks, Robert D. Seager, L. G. Barr

Faculty Publications

The measurement of fitness components in natural populations is among the most important problems of population genetics. Much effort has been devoted to the measurement of one aspect of the reproductive component of fitness, the storage and use of sperm by females.

The Effect Of Salt Concentration On Auxin Stability In Culture Media, James R. Dunlap, Stephen Kresovich, Robert E. Mcgee

Faculty Publications

The concentrations of indole-3-acetic acid (IAA), naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) were followed for 35 days in cell-free liquid medium containing 100, 50, or 0% Murashige-Skoog (MS) salt base. Although the concentrations of NAA or 2,4-D remained constant the level of IAA decreased to only 11% of the original concentration after 35 days in the presence of 100% MS salt base. The observed rate of IAA degradation was accelerated by the presence of MS salts.

Quantifying Spatial Patterns Of Overgrowth In Epibenthic Communities, David S. Wethey, Linda J. Walters

Faculty Publications

A method is presented that allows rapid and accurate measurement of changes in the spatial pattern of space occupation in encrusting organisms. The boundaries of organisms are represented as polygons, and geometric difference calculations are used to establish the perimeters of the areas gained or vacated between sampling dates. The influence of interspecific interactions on occupation of space is also quantified: geometric intersection calculations are used to define the perimeters of the areas gained or lost in overgrowth interactions. A method is presented for estimating the sampling frequency necessary for detection of significant changes in occupation of space. The method …

Management Of Plant Communities In Wilderness Areas, J. D. Mccullough

Faculty Publications

No abstract provided.

Limnological Aspects Of Upland Island: A Wilderness Area In East Texas, J. A. Sidnell, C W. Reed, J. D. Mccullough

Faculty Publications

No abstract provided.

Floristic Composition And Management Of East Texas Pitcher Plant Bogs, E. S. Nixon, J. R. Ward

Faculty Publications

No abstract provided.

Clonal Selection Of Sugar Cane For Texas And Louisiana From A Common Germplasm Pool, Stephen Kresovich, Richard D. Breaux

Faculty Publications

The sugar cane (a complex hybrid of Saccharum spp.) cultivar improvement program for the irrigated Lower Rio Grande Valley of Texas, initiated in 1961, has expanded greatly over the past 20 years. Initially, only 8 to 12 cultivars, selected from those previously released from commercial production in Louisiana or Florida, were screened annually for their production potential in the Lower Rio Grande Valley. The current introduction and screening program is more comprehensive utilizing 1) all clones advanced from the first to the second line trials at the U. S. Sugarcane Laboratory at Houma, Louisiana; 2) the advanced "CP" assignments from …

Microbial Degradation Of The Leachable And Lignocellulosic Components Of Leaves And Wood From Rhizophora Mangle In A Tropical Mangrove Swamp, Ronald Benner, Robert E. Hodson

Faculty Publications

Preparations of uniformly [¹⁴C] labeled mangrove leaves and specifically radiolabeled [¹⁴C-lignin] lignocelluloses and [¹⁴C -polysaccharide]lignocelluloses from mangrove leaves and wood were used in experiments to determine the microbial rates of mineralization of the leachable and lignocellulosic components of mangrove detritus in aerobic and anaerobic sediments of a tropical mangrove swamp. The bulk of the leachable fraction from mangrove leaves was mineralized relatively rapidly and was assimilated into microbial biomass with high efficiency (30 %). In contrast, rates of mineralization of the lignocellulosic component of mangrove leaves and wood were 10fold lower than mineralization rates …

Promoting Soft Mast For Wildlife In Intensively Managed Forests, John J. Stransky, John H. Roese

Faculty Publications

The fruit of woody plants is important as food for wildlife (Martin et al. 1951, Lay 1965). The relation of fruit production to southern forest stand conditions has been explored in only a few studies. Fruit production is greater in forest clearings than in closed forest stands (Lay 1966, Elalls and Alcaniz 1968). In Georgia slash pine (Pinus elliottii) plantations, fruit yields of shrubs are greatest in 4-yeas-old stands, and soil disturbance in site preparation greatly reduces fruit yields (Johnson and Landers 1978). Total fruit production is greatest in 5-year-old bedded loblolly pine (P. taeda) plantations …

Rearrangement Of The Keratin Cytoskeleton After Combined Treatment With Microtubule And Microfilament Inhibitors, Loren W. Knapp, W. Michael O'Guin, Roger H. Sawyer

Faculty Publications

In addition to containing microtubule and microfilament systems, vertebrate epithelial cells contain an elaborate keratin intermediate-filament cytoskeleton. Little is known about its structural organization or function. Using indirect immunofluorescence microscopy with an antikeratin antiserum probe, we found that destabilization of microtubules and microfilaments with cytostatic drugs induces significant alterations in the cytoskeletal organizationof keratin filaments in HeLa and fetal mouse epidermal cells. Keratin filament organizationwas observed to undergo a rapid (1-2 h) transition from a uniform distribution to an open lattice of keratin fibers stabilized by membrane-associated focal centers . Since addition of any one drug alone did not elicit …