The Trinity River flows through the Dallas-Ft. Worth Metroplex in north central Texas where it receives effluents from numerous point sources including seven large regional wastewater treatment facilities. Historically, the Trinity River has been impacted by massive wastewater loadings which often constitute > 80% of the total river discharge during low flow periods. Normally, high mass loadings correspond to the summer months, compounding the effects of a naturally stressful period, characterized by high temperatures and low dissolved oxygen concentrations. Samples from 12 stations were collected quarterly over an 18 month period from the Trinity River and two tributaries. Water samples were analyzed for a variety of water quality variables, including metals, priority pollutants, pesticides, and general water quality parameters. Water samples were also tested for acute and subchronic effects with several test species. Fish were collected at each station and assemblages were characterized using traditional classification techniques and the Index of Biotic Integrity. In addition, sediment samples were assessed for toxic effects which could have adversely impacted fish recruitment and in situ biomonitoring experiments were performed. Quantitative habitat characterization analyses were performed to gain additional information that could possibly explains differences in fish assemblage structure related to habitat variability. Data were analyzed using regression, univariate, multivariate, and descriptive statistical techniques and new approaches for analyzing impact assessment data were discussed. Results indicated that the most substantial impacts on fish assemblages were confined to a segment of the river where a sequence of point sources, in close proximity to each other, were overloading the river's capacity to sufficiently dilute and/or detoxify the effluent. Data also indicated the presence of episodic toxicity from nonpoint sources. In addition, toxic effects in sediment samples and differences in habitat were detected and may have contributed to measured differences among fish assemblages in the Trinity River.
Drumming behavior is described for the first time in 33 North American Plecoptera species, and signals of an additional five species, Pteronarcys pictetii, Acroneuria abnormis, Paragnetina media, Clioperla clio and Isogenoides zionensis, are further detailed. An out-group comparison of behavioral characters in all 104 world species whose drumming is known showed that the behavior is more advanced in the Arctoperlaria Group Systellognatha than in the Group Euholognatha. In general, tapping, monophasy, touching, sequenced exchange and less than 50 taps/answer are ancestral states, and rubbing, grouping, phasing, tremulation, interspersed exchange and equal or more than 50 taps/answer are derived states. There has been some co-evolution between abdominal structure and drumming behavior. Scanning Electron Micrographs of 30 species showed that the primitive state of tapping is ascociated with three classes of abdominal structure: (1) absence of derived structures, (2) lobes or vesicles, and (3) hammers. The derived behavior of rubbing, however, occurs only in species with derived structures, and is predominant in species having vesicles and hammers. Drumming can be used as a line of evidence to aid in defining genera and species, since the behavior has a variable degree of specificity or exclusiveness in all species, particularly in groups of species I have studied in the genera Isoperla, Pteronarcys and Taeniopteryx. Typical and variant computer-synthesized male calls of three stonefly species were tested with live females. They responded at high levels in such a way that the important informational content conveyed was identified as: (1) a minimal threshold of beat numbers, and (2) a discriminant window of beat intervals. Rub frequency and bibeat calling were critical informational parameters in two species.
Baroreflex function and cardiovascular responses to lower body negative pressure during selective autonomic blockade were evaluated in endurance exercise trained (ET) and untrained (UT) men. Baroreflex function was evaluated using a progressive intravenous infusion of phenylephrine HCL (PE) to a maximum of 0.12 mg/min. Heart rate, arterial blood pressure, cardiac output and forearm blood flow were measured at each infusion rate of PE. The reduction in forearm blood flow and concomitant rise in forearm vascular resistance was the same for each subject group. However, the heart rate decreases per unit increase of systolic or mean blood pressure were significantly (P<.05) less in the ET subjects (0.91 ± 0.30 versus 1.62 ± 0.28 for UT). During progressive lower body negative pressure with no drug intervention, the ET subjects had a significantly (P<.05) greater fall in systolic blood pressure (33.8 ± 4.8 torr versus 16.7 ± 3.9 torr). However, the change in forearm blood flow or resistance was not significantly different between groups. Blockade of parasympathetic receptors with atropine (0.04 mg/kg) eliminated the differences in response to lower body negative pressure. Blockade of cardiac sympathetic receptors with metoprolol (0.02 mg/kg) did not affect the differences observed during the control test. It was concluded that the ET subjects were less effective in regulating blood pressure than the UT subjects, because of 1) an attenuated baroreflex sensitivity, and 2) parasympathetic-mediated depression of cardiac and vasoconstrictive responses to the hypotensive stress.
Five species of stoneflies (Zapada haysi, Plumiperla diversa, Taenionema pacificum, Isoperla petersoni, Arcynopteryx compacta) from the North Slope and Interior of Alaska were examined for seasonal patterns of emergence of adults and growth of nymphs. Generally growth was retarded during the winter in this region, and all species except I. petersoni completed growth prior to January. The life cycles of six stonefly species (Prostoia besametsa, Triznaka signata, Sweltsa coloradensis. Isoperla fulva, Skwala parallela, Claassenia sabulosa) are described from northern New Mexico. In this region growth was generally less retarded during the winter than in Alaska; P. besametsa completed all nymphal growth during late fall and winter. Drumming behavior of a Colorado population of Pteronarcella badia was described using an evolutionary framework to explain the maintenance of signal variation in this species. Laboratory experiments were used to explore the effect of intraspecific and interspecific interactions on spatial partitioning in P. badia and Claassenia sabulosa. P. badia exhibited clumping and distributed itself as the surface area of substrate in low densities; however, in the presence of C. sabulosa its distribution was random and different from available surface area. A field study was used to examine spatial partitioning by three New Mexico stonefly species (I_. fulva, P. besametsa, T. signata) and to ascertain patterns of microdistribution relating to several abiotic and biotic factors. Generally, there was an interaction of the measured abiotic parameters (current, water temperature, time) with nymphal size. Additionally, void space and sample volume were successfully used to compare biotic densities among leaf and mineral substrates, which were higher in leaf packs than in mineral substrates.
Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^-1), moderately fit (MF, V0-2max=50.9±1.4 ml•kg^-1•min^-1), and low fit (LF, V0-2max=38.9±1.5 ml•kg^-1•min^-1). Orthostatic stress was induced using lower body negative pressure (LBNP) at -5, -10, -15, -20, -35, and -50 torr. Cardiopulmonary baroreflex responsiveness was assessed as the slope of the relationship between forearm vascular resistance (FVR, strain gauge plethysmography) and central venous pressure (CVP, dependent arm technigue) during LBNP<-35 torr. Carotid baroreflex responsiveness was assessed as the change in heart rate (HR, electrocardiography) or mean arterial pressure (MAP, radial artery catheter) elicited by 600 msec pulses of neck pressure and neck suction (NP/NS) from +40 to -70 torr. Pressures were applied using a lead collar wrapped about the subjects' necks during held expiration. Stimulus response data were fit to a logistic model and the parameters describing the curve were compared using two-factor ANOVA. The reductions CVP, mean (MAP), systolic, and pulse pressures during LBNP were similar between groups (P<0.05). However, diastolic blood pressure increased during LBNP m all but the HF group. (P<0.05). The slope of the FVR/CVP relationship did not differ between groups, nor did the form of the carotid-cardiac baroreflex stimulus response curve change during LBNP. changes in HR elicited with NP/NS were not different between groups (£>0.05). The range of the MAP stimulus response curve, however, was significantly less in the HP group compared to either the MP or LF group (£<0.05). These data imply that carotid baroreflex control of HR is unaltered …
The main purpose of this research was to investigate the phenomenon of tolerance to cocaine. Tolerance is operationally defined as a decreased drug effect due to prior history of drug administration. The animal model that was chosen to investigate tolerance to cocaine was the drug discrimination model, which is an animal analogue of human subjective drug effects. In the drug discrimination procedure, animals are trained to emit one behavior when injected with saline. In the present experiments, rats were trained to press one lever when injected with cocaine, 10 mg/kg, and a different lever when injected with saline for food reinforcement. Once rats are trained, they can accurately detect the cocaine stimulus greater than 95% of the time.
A population of the red-eared slider, Pseudemys scripta, in north central Texas was studied from 1975 to 1980. A life history energy budget was developed for a typical individual in the population and the population dynamics were estimated. A growth model relating growth rate to mean plastron length (PL) was developed from recapture data and used to 1) establish age classes and 2) age individuals. Growth rate was highly variable in both sexes. Females grew more rapidly than males and attained a larger maximum size (230 mm and 195 mm PL in females and males respectively). Females reached sexual maturity in their ninth year at a PL of 185-190 mm. Males matured in their sixth year at a PL of 90-100 mm. Females produced three clutches annually; clutch size ranged from 7 to 14 (X=10.3; N=20). Ova were enlarged in the early spring and ovulation began in late April and early May. Egg laying occurred from mid- May through June. Both egg size and clutch size increased with female body size. Lipid levels were variable within and among seasons. No annual lipid cycling pattern was evident in females. The proportion of assimilated energy devoted to reproduction, a measure of reproductive effort (RE), by females, was 13 per cent the first year of maturity (9 y) and increased to 20 per cent by their twentieth year. Lifetime RE was 16 per cent. Population density was estimated as 51 males and 50 females per ha in a 8.2-ha area of the lake. Young juveniles (less than 2 y) were not present although other subadult age classes were about equally represented. Fewer adults were encountered. An annual total production of 4000 eggs was estimated for the population present in 1977. A survival rate of from 2 to 18 per cent was estimated for …
Respiratory and metabolic patterns in response to variations in exercise workload (WL) and pedal frequency (RPM) were examined in 10 healthy males. Each subject performed WLs of low (L), moderate (M) and high (H) intensity, equivalent to 25%, 50% and 75% V02 m a x at 7 pedal frequencies (40, 50, 60, 70, 80, 90 and 100 RPM). ANOVA ( 3 X 7 design) indicated that WL and RPM had independent and significant effects on all respiratory and metabolic measures; i.e., the greater the WL and RPM, the higher the HR, V02, VC02, Ve, Fb, Vt, Vt/Ti, Vt/Te and Ti/TtQt and the lower the Ti and Te. However, analysis of the interaction effect revealed different response patterns for Fb, Vt, Ti, Vt/Ti, Vt/Te and Ve among the WLs. During L-WL, increases in RPM produced increases in Ve which were due to progressive increases in both Fb and Vt. However, during M-WL and H-WL, increases in RPM produced increases in Ve which were accomplished by a constant Vt and a progressive increase in Fb. My findings suggest that during low WLs, the signal for Vt is dependent on rate of contraction, while during M-WL and H-WL, the signal for Vt appears to depend on force of contraction and is independent of increasing RPM. When comparing the L-WL and M-WL, alterations in Ve, Fb, Vt/Ti and Vt/Te in relation to increases in pedal frequency were additive. However, when these two lower WLs were compared to the H-WL, the interaction between pedal frequency and Ve, Fb, Vt/Ti and Vt/Te was multiplicative. In addition, the interaction between WL and RPM on Vt and Ti was additive when comparing the M-WL and H-WL and multiplicative when these two lower WLs were compared to the H-WL. Correlation analysis indicated that for all WLs, Te was more …
Bacillus subtilis (ATCC 19659) were damaged by exposure to various concentrations of glutaraldehyde, as shown by decreased germination rates. The damage caused was repaired or otherwise obviated by the presence of sodium lactate in the holding medium. When two different salts of lactic acid were compared for ability to overcome the effect of glutaraldehyde, it was found that calcium salt of lactate was more effective than the sodium salt. The damage repair system involved l-alanine, lactate and either the sodium or calcium ions. The study involved in determining the difference in efficiency of spore repair was due to an organic or an amino acii snowed that the presence of two carboxylic functional groups did not effectively alter the reactivity.
High performance liquid chromatography was used to measure ribonucleoside triphosphates in microbial samples. Anion exchange columns in a radial compression module were used to separate and quantify purine and pyrimidine ribonucleotides. Endogenous ribonucleoside triphosphates were extracted from Escherichia coli and pseudomonas aeruginosa using three different solvents, namely trifluorocetic acid (TFA; 0.5M), trichloroacetic acid (TCA; 6 per cent w/v) and formic acid (1.0M) Extracts were assayed for uridine 5'-triphosphate (ATP), and guanosine 5'-triphosphate (GTP) by using anion exchange radial compression high performance (pressure) liquid chromatography. The three extraction produres were compared for yield of triphosphates. E. coli, the TFA extraction procedure was more sensitive and reliable than TCA and formic acid extraction procedures, but , in P. aeruginosa, the best yields of ATP and GTP were obrained following extraction with TFA. Yields of UTP and CTP increased when extraction was performed in TCA. These data illustrate that different extraction produres produce different measures for different triphosphates, a point often overlooked.
Collections of stoneflies (Plecoptera) were made at 603 stream sites from Nov. 1983 - May 1988 in the Ozark-Ouachita Mountain region, in relation to physiographic and vegetational characteristics. Examination of approximately 9000 vials from these collections, supplemented with material from major museums and other collectors, revealed 88 stonefly species in 8 families and 24 genera. Pearson's measure of association (R) showed there was a significant association between species present and each of the tested variables.
This investigation was concerned with determining the interaction of microwaves with germinating seeds. This study covers two different approaches. The preliminary efforts covered the response of germinating seeds to treatment by microwaves and heat. The second phase of the investigation used microwaves as a probe to determine some of the processes of early seed germination. The preliminary investigation measured the internal metabolic process by ATP production. Leakage of ions and organic material from germinating seeds indicated that membranes are a target of microwaves and heat. Electron photo-micrographs showed an increase in damage to membranes as heat and microwave treatments were increased. The second phase of this investigation was concerned with determining some of the biological activity at the initiation of germination of wheat seeds, Triticum aestivum L., using a resonating microwave cavity oscillating at 9.3 GHz as a probe. Direct current conductivity measurements were also made on the seeds as a means of confirming the observations made with the microwave cavity. There was no observable difference between treatment by UHF or heat in the ultrastructure of germinating seeds. A dielectric response far above that of free water was found as live seeds of wheat began to imbibe water. This effect was assumed to be due to the release of ions, because conductivity increased as corresponding quantities of water were imbibed; and both conductivity and dielectric response decreased as imbibition progressed. Although dead seeds also imbibe water, they do not show this decrease in dielectric response. The dielectric response of live seeds was reduced after the initial imbibition, showing that water became tightly bound as imbibition progressed. The dielectric response of actively growing shoots from the seeds was much less than that of the seeds themselves. The large quantity of water in the shoots is assumed to be immobile, being tightly …
During mitogen-induced transformation of human lymphocytes, phosphoglycerate kinase (PGK) exhibits new electrophoretic forms (pl=8.5-8.9). Electrophoresis and electrofocusing showed that the new forms are not due to expression of the autosomally linked isozyme found in semen (PGK-B; pl=9.7). The multiple electrophoretic forms are the result of protease modification of sex-linked PGK-A isozyme.When peripheral lymphocytes from young persons are stimulated in vitro with phytohemagglutinin, a selective increase in the levels of the glycolytic enzymes occurs concomitantly with blastogenesis. Human lymphocytes from a geriatric population were also subjected to mitogen stimulation. The initial levels of the enzymes were essentially identical in lymphocytes from young and old subjects as were mitogenfree cultured controls. However, during mitogen stimulation the cells from the old subjects failed to increase the glycolytic enzymes. This inability to activate glycolysis may be related to the decline in cell-mediated immunity which occurs with advancing age. Triosephosphate isomerase (TPI) has an increased thermolabile component in skin fibroblasts from patients with progeria (41.4 per cent)and Werner's syndrome (20.1 per cent) when compared with normal fibroblasts (0-3 per cent). The incorporation of various protease inhibitors failed to affect the percentages of heat-labile triosephosphate isomerases. The labile component appears to be identical to the deamidated form of the enzyme which accumulates in other aging cells. Isoelectric focusing demonstrated increased quantities of the deamidated TPI-A form in progeria and Werner's syndrome fibroblasts as compared to normal. The deamidated TPI-A was considerably more labile than the native TPI-B indicating the increased lability of triosephosphate isomerase in premature aging syndrome fibroblasts is due to an accumulation of the deamidated form of the enzyme. The levels of several proteases were found to be diminished in progeria fibroblast extracts as compared to normal. A deamidation mechanism of enzyme degradation plays a key role in the normal cellular catabolism of this …
Excessive nutrient loading of natural and artificial lakes has led, in some systems, to plethoric algal and aquatic macrophyte growth which can result in aesthetic degradation and undesirable tastes and odors. It would be advantageous to have some indication of the potential trophic status of a reservoir before it is filled. An objective of this study was to assess the water quality and nutrient loading potential of the tributaries entering Ray Roberts Lake, a large reservoir located in north central Texas. Samples from a maximum of thirteen sites were collected on the Elm Fork, Trinity River, Isle duBois Creek, and five additional tributaries. Data were also collected during six storms, from atmospheric deposition collectors, and from soil-water microcosms. The relationship between watershed landuse and mean water nutrient concentrations was evaluated. Significant differences will exist between the two major arms of Ray Roberts Lake: Elm Fork, Trinity River and Isle duBois Creek. While the majority of the annual phosphorus and nitrogen load entering both tributaries is coming from overland flow, the proportion is higher in Isle duBois Creek. Point sources in the Elm Fork contribute a larger percentage of the bioavailable phosphorus, which is significantly greater than in Isle duBois Creek. The water quality of Isle duBois Creek, especially nitrogen, is affected to a greater degree by the landuses in its watershed. Predictive regression models made accurate estimations of stream nutrient concentrations in Isle duBois Creek. The entire reservoir, upon reaching equilibrium conditions, will be classified as a eutrophic lake. The Trinity arm, with a higher phosphorus load, will display a higher trophic status. The Isle duBois arm has a lower phosphorus load which will give it a lower trophic status. The long hydraulic residence time of the two arms of the reservoir will remove nutrients upstream of the main body, …
The roles of Ca2 + and cAMP in olfactory transduction were explored using agents which affect calcium channels and second messenger systems. These agents were applied at certain calculated final concentrations onto olfactory epithelia of urethane-anesthetized frogs (Sana PiPlens) by two-sec aerosol spray. During extracellular recording, saturated vapors of isoamyl acetate were delivered every 100 sec in 0.3 sec pulses to produce an electroolfactogram (EOG). Inorganic cations that block inward calcium currents inhibit EOG responses with the following rank order: (La3+) > (Zn2+, Cd2+) > (Al3+, Ca2+, Sr2+) > (Co2+). Application of 7.5 mM La3+ eradicates £0G's, while Ba2+ (which can carry more current that Ca2+) initially produces significant enhancement (F=43.04, p<0.001, df=19). Magnesium ion has no effect on EOG's at 7.5 mM, while 1.5 X 10"4M Ca2+ is significantly inhibitory (F=5.74; p=0.0355; df=12). Control aerosol sprays of distilled water depress EOG's by an average of 5%. The organic calcium channel antagonists diltiazem and verapamil inhibit EOG's by 17% and 36X, respectively, at a concentration of 1.5 X 10~*M. Verapamil produces significant inhibition (F=17.17; p=0.002; df=ll) at 1.5 X 10" 5 M, while the 1,4-dihydropyridine calcium channel antagonists, nicardipine and nifedipine, do not inhibit beyond 1% DMSO controls. Several calmodulin antagonists decrease EOG's, but without correlation to their anti-calmodulin potency. Application of 1.5 X 10"*M chlorpromazine and N-(6-aminohexyl)-5-chloro-l-naphthalenesulfonamide inhibit EOG's by 31% and 27%, respectively, while trifluoperazine inhibits by 23%. Dibutyryl cAMP, a lipophilic mimic of cAMP, produces 54% inhibition at 1.5 X 10" *M. Dibutyryl cGMP, cGMP, cAMP, and adenosine all decrease EOG's by less than 15% compared to distilled water controls. Forskolin, a reversible activator of adenylate cyclase, inhibits EOG's by 57% at 1.5 X 10"5M, which is significant beyond the 1% DMSO controls (F=17.17; p=0.002; df=ll). These data support the hypothesis that Ca2+ participates in olfactory transduction. …
Presence-absence data for amphibians, chelonians, saurians, ophidians, and the terrestrial and aquatic ecological guilds of reptilians were analyzed using multivariate analyses. Geographically consistant distributional patterns were found for all faunal groupings. The correspondence between analyses of the different taxa and guilds was not perfect, but similarities were found. All analyses agreed on the presence of a distinctive region in east Texas. Most analyses also agreed on the presence of distinctive regions in south Texas, the Trans-Pecos, the Edwards Plateau, and north-west Texas. There is strong correspondence between interpretations of the analyses based on the amphibian, saurian, ophidian, and terrestrial reptilian distributions, and the biotic provinces produced by earlier, subjective analyses. The Edwards Plateau and a region on the western periphery of east Texas were found to be transitional between other, more faunally distinctive areas for most fauna! groups. Detailed examination of these regions suggested they are best described as clinal in nature. The environmental variables which were most effective in explaining patterns in the distribution of the various taxa and guilds were related to precipitation. However, variations in temperature and physiography were also important predictors of distribution for several of the groups. The distributions of soil and vegetation associations were also found to be related to amphibian and reptilian distribution.
Hazard assessment of pesticides in aquatic environments requires accurate predictions of persistence and compartmentalization. A strategy for developing confidence in predictive fate models, such as the Exposure Analysis Modeling System (EXAMS) and the Simplified Lake and Stream Analysis model (SLSA), is to test the models using carefully chosen chemicals in semi-controlled and field situations. An objective of this approach would be to isolate the variability in a particular fate process and thereby assess the ability of an algorithm to model the process. For example, endothall, a relatively watersoluble aquatic herbicide, has essentially a sole fate process, biotransformation. Endothall was used to test the predictive capabilities of EXAMS and SLSA and to identify sources of variance in those predictions.
The physiological responses of Myriophyllum spicatum to 2,4-D, diquat and copper were quantified using a plant tissue viability assay, and daily measures of dissolved oxygen and pH. Correlations of herbicide tissue residues to physiological response measures were determined and the relationship was used to develop exposure-response models. Diquat and copper had a greater effect on plant tissue viability than was observed for 2,4-D. Diquat produced greater reductions in dissolved oxygen concentrations and pH values than 2,4-D or copper. Copper exposure had the least effect on these parameters. Exposure-response models developed for 2,4-D predicted effective control at plant tissue residues ranging from 4000 to 4700 mg/kg. Aqueous exposure concentrations necessary to produce effective control plant tissue residues ranged from 0.20 to 0.40 mg/L. Exposure-response models developed for diquat predicted effective control at plant tissue residues ranging from 225 to 280 mg/kg. Aqueous exposure concentrations necessary to produce effective control plant tissue residues ranged from 0.113 to 0.169 mg/L. Exposure-response models developed for copper predicted effective control at plant tissue residues ranging from 680 to 790 mg/kg. Aqueous exposure concentrations necessary to produce effective control plant tissue residues ranged from 0.32 to 0.64 mg/L. Model predictions for 2,4-D, diquat and copper were within 0.5 mg/L of the manufacturers' label recommendations for these herbicides. The use of laboratory microcosms in development of exposure-response models for diquat and copper produced results comparable to those using the larger-scale greenhouse systems. Diquat effectively controlled M. spicatum at lower tissue residues than 2,4-D or copper. In addition, initial aqueous exposure concentrations were also lower for diquat. Use of these models in field situations should be coupled with considerations of quantity of biomass present and environmental conditions, such as turbidity, in order to accurately calculate exposure concentrations necessary for effective tissue residues. Thus, the use of these models …
Gray gulls Larus modestus are unique among birds of northern Chile as the only species nesting in the interior Atacama Desert, and the only seagull nesting far (30 - 100 km) from surface water. During breeding-nesting (August - February) gray gulls congregate on the coast of northern Chile where they feed and initiate courtship. As early as August, breeding pairs commute daily to the inner desert to establish nesting territories, round-trip distances of 60-200 Km. During incubation (30 days) and brooding (7 days) adults alternate daily foraging flights to the coast. Afterwards, both adults forage daily for their chick(s) until fledging (ca. 60 days). Foraging flights and thermoregulatory costs during the period of maximal solar radiation, when ground temperatures may reach 61 C in the day and drop to 2 C at night, have selected for adaptations which minimize those costs: tolerance of hypothermia and hyperthermia; dark plumage; low egg-shell water vapor conductance; low standard metabolic rate; elaborate repertory of thermoregulatory behavior which allow adults to take advantage of microclimatic variations in the desert and minimize costs relative to a sympatric congenor, Larus belcheri scheduling foraging flights to take advantage of optimal atmospheric conditions and presence of forage fish (anchovies) close to the surface; scheduling migration to coincide with anchovy production and levels of interspecific competition; and reduced clutch size ( ≤ 2) relative to most seagulls. Periodic El Nino-Southern Oscillations (ENSO), which reduce principal food items of gray gulls, have selected for 'bet hedging" tactic by which L. modestus either ceases reproduction or varies clutch size between one and two, as observed during and after the 1982-83 ENSO. During a typical reproductive season, breeding pairs allocate a minimum of 39 percent of their net metabolized energy (NME) to foraging flights. Including energy content of eggs, females have an overall …
Between February 1986 and October 1988, 863 amphibians and reptiles were collected in northcentral Texas and examined for coccidial parasites. Thirteen percent of amphibians <26% salamanders, 11% frogs and toads) and 28% of reptiles (54% turtles, 25% snakes) harbored 20 previously described and 16 new species of coccidia; overall prevalence of infection was 176/863 < 20%). Sixteen Ambvstoma texanum were infected with Eimeria ambystomae which represents new host and geographic locality records for the coccidium. Forty anurans were found to be passing coccidia, including Pseudacris streckeri. Bufo valliceos and Gastrophryne olivacea. Four new species of coccidia were described from anurans and include Eimeria flexuosa. E. streckeri. Isospora dellcatus and I_. fraaosum. However, oocysts found in B. v.. valliceps were determined experimentally to represent pseudoparasites. Sixty-eight turtles were infected with coccidia, including Chelvdra serpentina, Kinoeternon flavescens. Pseudemvs texana. Terrapeng ornata and Trachemvs scripta eleoans. Fourteen eimerians (5 of which are described as new species) were found in turtles. The new species from turtles include Eimeria cooteri, E. ornata, E. Btvlosa. E. texana and E. trachemvdis. Interestingly, all 96 lizards examined were negative for coccidia. Fifty-three snakes including 11 colubrids and 1 viperld harbored coccidia of the genera Caryospora. Cryptosporidium. Eimeria and Sarcocystis: prevalence of infection was highest in 3 species of North American water snakes <Nerodia spp.). Seven new species of Eimeria were described from snakes, including E. conanti. E. lnfirmus. E. papillosum. E. rhombifera. E. serpenticola. E. striatula and E. tenuis. There was no preference for coccidia between the sexes of any hosts. Based on limited data from a single anuran host, prevalence was higher during wetter months of spring than in summer. In addition, prevalence was higher in aquatic and semiaquatic snakes than in truly terrestrial species. Preliminary data suggested that using host specificity data of coccidia may be …
Autotomy (self-induced loss) of body parts has evolved independently as a predator defense mechanism in several major animal phyla. The mechanism among vertebrates, including 13 of the 20 recognized lizard families, is tail autotomy. Its occurrence among the majority of lizard families offers an excellent opportunity to examine the effects of a major selective force on the ecology and evolution of a group of organisms. The research of this study was designed to examine experimentally (i) the function of tail autotomy, (ii) the function of autotomized tail movement, (iii) the energetics of autotomized tail movement, and (iv) the energetic costs of autotomy of an energy-rich tail to reproduction.
The classification of the Azotobacteraceae to the level of genus and species has been uncertain since the studies of Beijerinck in 1901. This dissertation represents an effort to establish a system of classification more complete than the one now in use. In this study, both qualitative and quantitative taxonomy were used in order to establish a well founded classification scheme. Qualitative methods included certain important morphological and physiological characteristics, isoenzyme patterns, and immunological reactions. Quantitative methods included numerical taxonomy (based on total morphological and physiological characteristics) and numerical analysis of protein profiles. All the data from these experiments were subject to comparison with other genotypic and phenotypic data.
The relationship among eosinophils, lysophospholipase activity and the immune response in animals infected with Trichinella spiralis was studied using in vivo and in vitro techniques. In an in vivo experiment, anti-thymocyte serum (ATS) was administered to mice infected with T. spiralis and its effects on intestinal lysophospholipase (EC 3.1.1.5.) activity, peripheral blood, bone marrow and intestinal eosinophilia were measured in the same experimental animal. The ATS caused a significant temporally related suppression of both the tissue lysophospholipase response and eosinophilia, in all three compartments. These findings support the hypothesis that parasite-induced eosinophilia is the cause of the increased lysophospholipase activity of parasitized tissue and that the responses are thymus cell-dependent. In vitro experiments demonstrated that the eosinophil was the primary inflammatory cell source of lysophospholipase among eosinophils, neutrophils macrophages and lymphocytes. The role of other cells and antigen in the production of the enzyme by the eosinophil was also investigated in vitro• Results demonstrated that eosinophils cultured with both T. spiralis antigen and other leukocytes yielded enzyme activities significantly greater than eosinophils cultured alone or with only antigen. More specific experiments showed that T-lymphocytes were the cells responsible for influencing the eosinophils' lysophospholipase activity in the presence of antigen, and that their influence was enhanced by the presence of macrophages. These results suggested that increased lysophospholipase activity present in parasitized tissue was not only due to increased numbers of eosinophils infiltrating parasitized tissue but was also due to each eosinophil synthesizing more of the enzyme. The necessity for antigen and other cells suggests a role for cell cooperation in the production of the enzyme, specifically T-lymphocytes and macrophage interaction with the eosinophil. A lymphocyte soluble factor collected from sensitized lymphocytes stimulated with specific antigen or concanavalin A was found to enhance the eosinophil lysophospholipase activity when added to cultures of …
The initial step in odor recognition by the nose is the binding of odorant molecules to receptor sites embedded in the dendritic membranes of olfactory receptor cells. Despite considerable interest and experimentation into the nature of these receptor sites, little is known of their specificity to different types of odorant molecules. This lack of knowledge partially stems from the fact that the nature of receptor proteins is most effectively studied when specific and irreversible inhibitors are available for use as chemical probes, yet no such agents have been discovered for use in the olfactory system. A series of alkylating agents and other chemically active odorants were tested to determine whether they might react with specific odorant receptors and modify olfactory responses. Electroolfactogram (EOG) recordings were obtained before, during, and after treatment of the olfactory mucosae of grass frogs (Rana pipiens) with a chemically active odorant.
The objective of this research was to study the pyrimidine salvage pathways of Rhizobium. Three approaches were used to define the pyrimidine salvage pathways operative in two species of Rhizobium, R. meliloti and R. leguminosarum . The first approach was to ascertain the pyrimidine bases and nucleosides that could satisfy the pyrimidine requirement of pyrimidine auxotrophs. Uracil, cytosine, uridine or cytidine all satisfied the absolute pyrimidine requirement. The second approach was to select for mutants resistant to 5-fluoropyrimidine analogues which block known steps in the interconversion of the pyrimidine bases and nucleosides. Mutants resistant to 5-fluorouracil lacked the enzyme uracil phosphoribosyltransferase (upp ) and could no longer use uracil to satisfy their pyrimidine requirement. Mutants resistant to 5-fluorocytosine, while remaining sensitive to 5- fluorouracil, lacked cytosine deaminase (cod) and thus could no longer use cytosine to satisfy their pyrimidine auxotrophy. The third approach used a reversed phase HPLC column to identify the products that accumulated when cytidine, uridine or cytosine was incubated with cell extracts of wild type and analogue resistant mutants of Rhizobium. When cytidine was incubated with cell extracts of Rhizobium wild type, uridine, uracil and cytosine were produced. This Indicated that Rhizobium had an active cytidine deaminase (cdd) and either uridine phosphorylase or uridine hydrolase. By dialyzing the extract and reincubating it with cytidine, uridine and uracil still appeared. This proved that it was a hydrolase ( nuh ) rather than a phosphorylase that degraded the nucleoside. Thus, Rhizobium was found to contain an active cytidine deaminase and cytosine deaminase with no uridine phosphorylase present. The nucleoside hydrolase was active with cytidine, uridine and to a far lesser extent with purines, adenosine and inosine. When high concentrations of cytidine were added to mutants devoid of hydrolase, cytosine was produced from cytidine - 5-monophosphate by the sequential action …
Sediments in the Trinity River were chemically, physically and biologically characterized and assessed for toxicity. Laboratory bioassays were conducted to identify sediments which induced toxic responses in test organisms and to document these responses through time. Metal and organic contaminant concentrations in bottom sediments were measured. Relationships between these concentrations and biological responses observed in laboratory bioassays were determined. Toxicity identification / reduction methods were used to characterize sediment toxicants. Sediment oxygen demand was also measured in resuspended and undisturbed bottom sediments through time. The Background Sediment Chemistry Approach and the Sediment Bioassay Approach were used to assess sediment quality. Sediment toxicity was observed in whole sediment bioassays using Chironomus tentans as the test species. A relationship between sediment contaminant concentration and toxicity was observed in approximately sixty percent of the sediments. Oxygen demand of resuspended sediments was elevated in sediments at two locations on the river. Oxygen demand of undisturbed sediments was elevated at one location on the river. Characterization of sediment toxicants was conducted using EDTA, pH, and carbon treatments and manipulations of the sediments. Aeration tests were also used to evaluate the contribution of volatile organic contaminants to observed toxicity.
Aspartate transcarbamoylase (ATCase; encoded by pyrBI genes) is one of the most studied regulatory enzymes in bacteria. It is feedback inhibited by cytidine triphosphate (CTP) and activated by adenosine triphosphate (ATP). Much is known about the catalytic site of the enzyme, not nearly as much about the regulatory site, to which CTP binds. Until now a positive selection for feedback-modified mutants was not available. The selection we have developed involves the use of a pyrA deletion in S. typhimurium. This strain lacks carbamoylphosphate and requires both a pyrimidine and arginine for growth. In this strain citrulline is used to satisfy the pyrimidine and arginine requirements. The minimal flow through the pyrimidine pathway from the citrulline-produced carbamoylphosphate is exquisitely sensitive to feedback control of ATCase by CTP. By elevating the CTP pool, via exogenous cytidine, in a strain that also contains a cytidine deaminase mutant (cdd) growth can be stopped completely, indicating 100% inhibition. It was therefore possible to measure in vivo feedback inhibition of ATCase among the citrulline users and to isolate a family of ATCase regulatory mutants with either modified or no response to effectors.
Corynebacterium poinsettiae mutant strains blocked in carotenoid biosynthesis were obtained by treatment with the mutagen N-methyl-N1-nitro-N-nitrosoguanidine. Additional carotenoid (Crt) mutant strains were obtained from a previous study conducted in our laboratory. Fifty-nine Crt mutants affected in carotenoid biosynthesis were examined by a normal phase high performance liquid chromatography (HPLC) system. Pigment extracts of Crt mutants and C. poinsettiae wild type strains were resolved by an isocratic system with hexane:acetone:dicholoromethane, 11.35:1.73:1.00 (by vol.) as the eluting solvent. In addition to the five major peaks, twelve minor peaks were observed in the wild type C. poinsettiae strain used in this study. Crt mutant and wild type strain peak heights were measured from the individual chromatograms and the peak height data set created was analyzed using the Statistical Analysis System program to perform a cluster analysis. The cluster analysis revealed five carotenoid mutant groups. Carotenoid pigments which accumulated or were absent in each of the cluster groups are reported. Cluster group 1 mutants (CrtA) are blocked in the dehydrogenase(s) which is(are) responsible for the dehydrogenations between phytoene and lycopene. Cluster group 2 mutants (CrtB) appear to be blocked at a second dehydrogenase specific for the dehydrogenation from C.p. 470 to C.p. 496. Cluster group 3 mutants (CrtC) are blocked at a cyclization step in the pathway which involves cyclization of C.p. 496 to C.p. 470 and which may cyclize C.p. 473 to C.p. 450. The genes CrtA and CrtB map only 0.5 map units from each other while CrtA and CrtC map 2.1 map units from one another. Mutants which accumulate end products but which lack certain precursors indicate a branched pathway for pigment biosynthesis exists in this organism. Media for the formation, fusion and regeneration of C. poinsettiae protoplasts are reported and a protocol for the use of these media in genetic …
A research program was developed to investigate basic and applied aspects of toxicity, both lethal and sublethal, of hemoxidants, particularly nitrite, on fish, non-fish aquatic vertebrates, and crayfish. The major objectives of this research were to determine A) acute and sublethal toxicity of nitrite to selected aquatic organisms: 1. aquatic salamander larvae, Ambystoma texanum, 2. swamp crayfish, Procambarus simulans, 3. bluegill, Lepomis macrochirus, 4. bullfrog, tadpoles, Rana catesbiana, 5. channel catfish, Ictalurus punctatus, B) the influence of environmental chloride on acute and sublethal exposures to hemoxidants: 1. on acute nitrite toxicity to salamander larvae, crayfish, and bluegill, 2. on nitrite-induced methemoglobinemia in bullfrog tadpoles, Rana catesbian, C) the effect of environmental hydrogen ion concentrations (pH) on acute nitrite toxicity 1. to the crayfish, Procambarus simulans, 2. to the bluegill, Lepomis macrochirus, D) the effect of temperature in sublethal exposures to nitrite 1. methemoglobin formation in channel catfish exposed at different acclimation temperatures, 2. recovery from methemoglobinemia at different acclimation temperatures, E) the effect of the fish anesthetic TMS-222 on nitrite-induced methemoglobinemia in channel catfish 1. supression of nitrite-induced methemoglobinemia, 2. dose-response curve for TMS-222 induced methemoglobinemia, and F) if a methemoglobin reductase system is present in channel catfish.
A series of experiments provided data to parameterize and validate a coupled herbicide fate and target plant species effects model. This simulation model is currently designed to predict responses of water hyacinth populations to treatments of the dimethylamine formulation of 2,4- dichloro-phenoxy acetic acid (2,4-D -DMA). Experiments investigated 1) the response of water hyacinth to varying exposures of 2,4-D (DMA); 2) the role of water hyacinth density and herbicide interception in treatment effectiveness using 2,4-D (DMA); and 3) the importance of root exposure to obtain control of water hyacinth using 2,4- D (DMA). Results demonstrated the importance of leaf or canopy interception of 2,4-D (DMA) sprays in obtaining control of water hyacinth populations. The critical threshold plant tissue concentration of 2,4-D (DMA) required to elicit maximum mortality (98%) was estimated to be approximately 12 mg 2,4-D per kg water hyacinth tissue (wet weight). Root uptake apparently plays little or no role in the effectiveness of this herbicide for controlling water hyacinth growth. Validation trials illustrated the efficacy of the current model. The model was validated with data from a field operation. This research has provided considerable insight into optimal use of this auxin-type herbicide for control of water hyacinth, a monocotyledon.
Sorghum plants excrete phenolic acids which reduce subsequent crop yields. These acids accumulate in field soil by combining with soil and clay particles to form stable complexes which remain until degraded by bacterial metabolism. The amount of phenolic acids in soil samples were obtained by gas chromatography measurements, while Azotobacter populations were obtained by plate counts in 40 sorghum field samples from Denton County, Texas. One can conclude that increasing the Azotobacter population in the soil increased the degradation rate of phenolic acids proportionally. It is proposed that seed inoculation will introduce selected strains of Azotobacter into the soil. The presence of Azotobacter should increase crop size in subsequent plantings.
Genetic variation was analyzed for populations of seven taxa comprising four cytotypes of the Geomys bursarius chromosome complex, including G. b. major, G. b. knoxjonesi, and the Edwards Plateau taxa, G. b. llanensis and G. b. texensis. Genetic relationships of the Edwards Plateau gophers with other taxa and between themselves were examined. Genetic similarity, number of fixed allelic differences, and ectoparasite distribution indicate the Edwards Plateau gophers are a distinct gene pool. Isolation of the Edwards Plateau taxa precludes contact zone analysis. However, genetic differentiation is typical of that between other species of Geomys, and the Edwards Plateau taxa should be recognized as G. texensis. Distributions of allelic frequencies indicate little justification in retaining the subspecific status of the Edwards Plateau forms.
Nucleotide pools were extracted and quantified from Pyr^+ and Pyr^- strains of P. aerucjinosa. Strains were grown in succinate minimal medium with and without pyrimidines, and nucleotides were extracted using trichloracetic acid (TCA; 6% w/v). The pyrimidine requirement was satisfied by uracil, uridine, cytosine or cytidine. Pyr^- mutants were starved for pyrimidines for two hours before nucleotide levels were measured. This starvation depleted the nucleotide pools which were restored to wild type levels by the addition of pyrimidines to the medium. When the pyrimidine analogue, 6-azauracil, known to inhibit OMP decarboxylase, was added to cultures of the wild type strain, the uridine and cytidine nucleotides were depleted to near zero. Thus, the nucleotide pool levels of Pseudomonas strains can be manipulated.
The objective of this investigation was to examine the changes in the nucleotide pools of Azotobacter vinelandii during the growth cycle. Endogenous ribonucleotides were extracted from A. vinelandii using trichloroacetic acid (TCA; 12% w/v). The 5' mono-, di- and triphosphates of adenine, guanine, uracil and cytosine were separated and quantified by anion-exchange high performance liquid chromatography. Results indicated that the adenylate energy charge of A. vinelandii paralleled the growth rate during exponential phase and that it declined rapidly as the stationary phase was reached. In addition, the amount of each nucleotide in A. vinelandii tended to increase in the logarithmic phase and decrease in the stationary phase in a similar manner to the energy charge.
The drug, N,N bis (ethylene)-P (1-adamantyl) phosphonic diamide inhibits focus formation of Rous Sarcoma Virus in tissue culture. Transformation of chick cells was inhibited when the drug was added to chick cells prior to infection. The drug did not inhibit the transformation of Normal Rat Kidney Cells infected with RSV, when the cells were grown at non-permissive temperatures and shifted to permissive temperatures upon addition of the drug. Nor did the drug revert cells transformed at permissive temperatures. These studies indicated that the inhibition of RSV is in the early stage of viral growth, possible penetration or uncoating.
The role of Ca++ in olfactory responses was investigated with inorganic and organic calcium channel antagonists. Electrophysiological responses to odorants were recorded from frog olfactory mucosa before and after aerosol application of different agents. Electroolfactogram responses were blocked by certain inorganic ions with the order of effectiveness Zn++ >Ln+++>Cd++>Ca++>Co++>Sr++>Mg++. Ba++ potentiated olfactory responses, and is known to potentiate calcium channel-mediated responses in other tissues. Certain local anesthetics which are thought to act through calcium channel blockade were inhibitory to olfactory responses, with the order of effectiveness being dibucaine>tetracaine>procaine. These data support the idea that Ca++ is involved in olfaction, perhaps acting as a current carrier and/or a second messenger. Preliminary experiments on channel localization were performed using a silicon-labeled amine. Attempts to localize the silicon label were inconclusive, although silicon was detected in the olfactory tissue.
A gene dosage study was conducted on a rare complete trisomy 22 human fibroblast cell line utilizing three lysosomal enzymes, ∝-iduronidase, ∝-galactosidase B, and arylsulfatase A, whose genes are located on chromosome 22 and two control enzymes, ,β-hexosaminidase A and -- fucosidase, with genes not on chromosome 22. A gene dosage effect was clearly demonstrated for an early passage number of the fibroblasts; however, later passage numbers gave inconclusive results. This study suggests that gene dosage studies must be carefully designed to be conducted only on early, matched passage number cells. ∝-fucosidase gave anomalous results most likely due to pleiotropic effects. The present gene dosage study confirmed the trisomic nature of the cell line studied and suggests that this type of study may be a useful diagnostic tool for small deletions, additions, or unbalanced translocations.
Genetic variation was examined in bluehead wrasse, Thalassoma bifasciatum, populations along the Florida Keys. Interpretion of mean heterozygosity (H), percent polymorphic loci per population (P), genetic similarity, and F and G statistics demonstrated a clear division of wrasse populations into "northern" and "southern" groups. Correlation and cluster analyses indicated the six reefs can be grouped in a similar fashion based on genetic and environmental data. The conclusion from this analysis of wrasse populations in the Florida Keys is that substantial population subdivision occurs in response to differing selective pressures created by heterogeneous environments.
In five separate experiments, weight-adjusted doses of TEM, EMS, and ENU were injected intraperitoneally into twelve week-old female mice six hours after mating. On day seventeen of gestation, the females were sacrificed and their uterine contents were examined. The effect of each agent was determined by its ability to cause malformations and death to the developing embryos. All treatment groups showed statistically significant elevated levels of malformations in comparison to their corresponding control groups. The reproductive damage induced in these experiments cannot be singularly attributed to teratogenesis or mutagenesis but a combination of the two.
Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant correlation between sediment toxicity and sediment characteristics (organic carbon, cation exchange capacity, particle size distribution, particle surface area). Fluoranthene amended sediments with similar organic carbon contents do not yield similar toxicities due to sorbed fluoranthene and thus do not support the organic carbon normalization approach for evaluating sediment quality or for sediment criteria development.
Dominant genera of bacteria were isolated from three river waters during anthracene and pentachlorophenol biotransformation studies. The genera Pseudomonas, Acinetobacter, Micrococcus, Chromobacterium, Alcaligenes, Azomonos, Bacillus, and Flavobacterium were capable of biotransforming one or both of these compounds. These isolates were subjected to further biotransformation tests, including river water and a basal salt medium with and without additional glucose. The results of these experiments were evaluated statistically. It was concluded that only a limited number of the bacteria identified were able to transform these chemicals in river water. The addition of glucose to the growth medium significantly affected the biotransformation of these chemicals. It was also determined that the size of the initial bacterial population is not a factor in determining whether biotransformation of anthracene or pentachlorophenol can occur.
Ecological research involving habitat studies was conducted on the Elm Fork of the Trinity River in Denton County, Texas, from spring 1985 to spring 1986. Habitat Evaluation Procedures and Habitat Suitability Index Models developed by the United States Fish and Wildlife Service were applied to a 1419 hectares study area to determine the quality of habitat for four species: beaver, Castor canadensis, wood duck, Aix sponsa, pileated woodpecker, Dryocopus pileatus, and white crappie, Poxomis annularis. Population estimates were generated. A wildlife management plan was developed for the study area. Habitat Suitability Index Models were found to be overly conservative, underestimating the quality of habitat in areas of ecological transition.
After dendrite transection, two primary injury current pathways may acount for cell death: (1) the lesion current at the site of injury and (2) the voltage sensitive calcium channels along the dendrite. Lesions were made with a laser microbeam in mouse spinal monolayer cell cultures. Polylysine was tried as a positively charged "molecular bandage" to block the lesion current. The calcium channel blockers, verapamil and nifedipine, were used to reduce the calcium channel current. Control toxicity curves were obtained for all three compounds. The results show that neither verapamil, nifedipine, nor polylysine (MW: 3,300) protect nerve cells after dendrite amputation 100 ptm from the soma. The data also indicate that these compounds do not slow the process of cell death after such physical trauma.
Qualitative and microcosm models were used to predict effects of herbicide application for control of Myriophyllum spicatum. Predictions were compared to data from Pat Mayse Lake, a Texas reservoir, where localized areas were treated with endothall. Although milf oil was temporarily eliminated, when endothall was used according to manufacturer's directions, no ecologically significant direct or indirect effects were observed on nontarget species or abiotic water quality. Comparisons of the predictions with field data confirmed the capabilities of this approach for estimating risk and emphasizing the importance of identifying regulating or driving factors that modify environmental impacts of aquatic weed control programs so they can be incorporated into future risk assessments.
The feeding ecologies of leaf pack-associated systellognathan stoneflies were examined from 6 June 1980 21 May 1981. Species composition, seasonal abundance, nymphal growth, feeding habits and mouthpart morphology were determined for the eight dominant stonefly species. Prey preferences and predator-prey size relationships were also examined for omnivorous and carnivorous species. Foregut analysis from 2860 individuals indicated opportunistic feeding on the most abundant prey insects, usually in proportion to prey frequency. Feeding preference studies generally indicated random feeding on major prey groups. Prey and predator sizes were usually highly correlated (p<0.01), with predators expanding their prey size thresholds with growth. The potential for competition between sympatric stoneflies for prey is discussed.
Adult stonefly emergence, nymphal growth, drift and microdistribution were examined in Battle Branch, a secondorder, spring-fed stream, from November, 1982 to May, 1984. Adults of 22 species emerged successionally, with specific adults present every month. Searching emergent objects and the stream margin was best for collection of winter and early spring emerging species. Sweeping the streamside and light trapping were most efficient for late spring and summer emerging species. Nymphal growth for nine abundant species generally fit double log or semilog models. Drift was low, but did show a post-sunset pulse. Generally, leaf material was found to be significantly related (p<O.001) to density, diversity and biomass of stoneflies in Battle Branch.
When Y-1 mouse adrenal tumor cells were treated with sodium orthovanadate, an intermediate filament (IF) inhibitor in BHK21-F cells, there was no change in the amount of 20α-dihydroprogesterone produced. A neurofilament inhibitor, β, β'-iminodipropionitrile (IDPN), enhanced the ability of Y-1 cells to produce steroid in response to ACTH by acting on the plasma membrane. Electron microscopy of Y-1 cells extracted with Triton X-100 revealed that both vanadate and IDPN caused the aggregation of cytoskeletal and granular structures in the perinuclear area. The steroidogenic effects of IDPN suggest that the perinuclear aggrergation of cytoskeletal structures may result from the detachment of IF from the plasma membrane, while the reason for the cytoskeletal changes by vanadate is unknown.
Extraction and quantitation of myosin light chain two coupled with myograph recordings from Ascaris muscle perfused with calmodulin inhibitors and neurotransmitters in conjunction with their respective agonists and antagonists have been used to establish the regulation of contraction in this muscle. Densitometric tracings of isolectric focusing gels separating the regulatory light chain were used to quantitate phosphorylation in resting, contracted and flaccid muscle. These studies indicated that inhibitory neurostimulation is mediated by a true GABA receptor. Myosin-mediated contraction is responsible for maintaining the level of tension observed in resting actin-mediated muscle. Actin-mediated contraction is responsible for the rapid rise in tension following excitatory stimuli. Both systems function simultaneously and are independant.
Drumming is first described for five North American stonefly species, Acroneuria evoluta, Doroneuria baumanni, Isoperla namata, Chernokrilus misnomus, and Pictetiella expansa. Signals of Acroneuria lycorias, Phasganophora capitata and Isoperla signata are further described. Drumming was not recorded from Amhinemura delosa. Signals of A. evoluta are the most complex yet recorded in Plecoptera. Doroneuria baumanni, P. expanse, C. misnomus and P. capitata have 2-way exchanges. Male D. baumanni produce two prolonged beats by rubbing the hammer on the substratum; male-female signals are non-overlapping in the first two species and overlapping in the latter two. Female P. capitata answered with an unusually long sequence of beats. Two male Isoperla species produced monophasic calls without female answers. Female A. lycorias answered taped male signals with monophasic signals like all observed females.
Using cultured Y-1 mouse adrenal tumor cells which produce the steroid 20(-hydroxypregn-4-en-3-one (20-DHP), it was found that 10-5 M corticosterone and deoxycorticosterone increased basal and inhibited ACTH-induced 20-DHP production. The steroid effects were concentration-dependent, reversible, and specific since six other steroids did not stimulate steroidogenesis and varied in their ability to inhibit ACTH-induced steroidogenesis. Cytochalasin D inhibited steroid-stimulated 20-DHP production, suggesting a mechanism of steroid stimulation similar to that of ACTH. Steroidogenesis stimulated by cholera toxin, (Bu) 2 cAMP, or pregnenolone was not inhibited by exogenous steroid; corticosterone increased basal and inhibited ACTH-induced intracellular cAMP production. Steroids altered cell surface morphology. These findings suggest that steroids alter adrenal steroidogenesis by acting within the plasma membrane.
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