Showing papers by "University of Arkansas published in 1981"

Relationship of nitrogen to the onset and suppression of ligninolytic activity and secondary metabolism in Phanerochaete chrysosporium

Abstract: Ligninolytic activity in the white-rot fungus Phanerochaete chrysosporium was previously found not to be induced by lignin, but to develop in cultures in response to nitrogen starvation Added NH4+suppressed existing activity The present study examined amino acid profiles and protein concentrations during onset of ligninolytic activity (synthetic 14C-lignin→14CO2) in nitrogen-limited cultures, and defined some characteristics of subsequent suppression by added nutrient nitrogen During the transition between depletion of medium nitrogen and the onset of ligninolytic activity, total free intracellular amino acids increased, then rapidly decreased; changes in glutamate concentration played a major role Intracellular protein concentration fluctuated in a manner roughly converse to that of the concentration of free amino acids Protein turnover was rapid (5–7%/h) during the transition period Glutamate, glutamine, and histidine were the most effective of 14 nitrogenous compounds in suppressing ligninolytic activity after its onset The suppressive effect was not mediated through carbon (glucose)-catabolite repression or by alterations in culture pH Activities responsible for oxidation of lignin and the ligninrelated phenol, 4-hydroxy-3-methoxyacetophenone, responded similarly to added nitrogen Synthesis of a secondary metabolite, veratryl alcohol, like lignin oxidation, was suppressed quite sharply by glutamate and significantly by NH4+ Results indicate that nitrogen metabolism affects ligninolytic activity as a part of secondary metabolism, and suggest a role for glutamate metabolism in regulating this phase of culture development

Observations on the root anatomy of rice (oryza sativa l.)

Abstract: Rice plants were grown hydroponically and roots were prepared for light and electron microscopy using standard techniques. The roots are bounded by an epidermis, exodermis, and fibrous layer. The exodermis has a suberin lamella along its inner tangential wall. The fibrous layer is composed of thick-walled lignified cells with little pitting. The cortical parenchyma is compact when young, but expands and separates to form a zone of cell walls and air spaces in a spoked arrangement. Supporting columns of living parenchyma cells are occasionally present, particularly near lateral roots. The endodermis is typical for grasses with Casparian strips, suberin lamellae, and tertiary state walls with numerous pits. The pericycle and pith become sclerified. Protoxylem elements alternate with protophloem in the young root; later, early metaxylem, late metaxylem, and metaphloem proliferate. The exodermis, fibrous layer, lacunate cortex, and endodermis appear to present a formidable barrier to radial ion movement in the mature portions of the root.

Kimmswick: A clovis-mastodon association in Eastern Missouri

Abstract: Stone tools characteristic of the Clovis culture have been found in direct association with bones of the American mastodon at Kimmswick, Missouri. The vertebrate fauna from Clovis components suggests a deciduous woodland and meadow habitat. Such an environmental reconstruction provides a new perspective for Clovis adaptations and the ecological tolerances of Mammut americanum.

The binding of N-hydroxy-2-acetylaminofluorene to DNA and repair of the adducts in primary rat hepatocyte cultures.

Abstract: Primary cultures of rat hepatocytes were exposed to [ring-3H]-N-hydroxy-2-acetylaminofluorene (N-OH-AAF) for 4 h, and the RNA and DNA nucleoside adducts were isolated and identified by h.p.l.c. The DNA adducts were shown to be N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF), N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF), and 3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene (dG-N2-AAF), while the RNA adducts were N-(guanosin-8-yl)-2-acetyl-aminofluorene, and N-(guanosin-8-yl)-2-aminofluorene. The removal of these adducts was measured up to 38 h following the cessation of exposure of the hepatocytes to N-OH-AAF. The dG-C8-AAF adduct was removed with a half-life of approximately 10 h, while dG-N2-AAF and dG-C8-AF remained constant for 14 h, followed by a slow rate of removal. The dG-C8-AAF adduct initially composed about 60% of the total DNA adducts of primary hepatocytes in contrast to the 20% found in liver in vivo. The formation of the 3 DNA adducts and the different rates of repair indicate that primary cultured rat hepatocytes may be a valuable system to study initiation of liver carcinogenesis by N-OH-AAF.

Ligninolytic activity of Phanerochaete chrysosporium : Physiology of suppression by NH 4 + and l -glutamate

Abstract: Previous research showed that addition of nutrient nitrogen to ligninolytic (stationary, nitrogen-starved) cultures of the wood-decomposing basidiomycete Phanerochaete chrysosporium causes a suppression of lignin degradation. The present study examined early effects on nitrogen metabolism that followed addition of NH 4 + and l-glutamate at concentrations that yield similar patterns of suppression. Both nitrogenous compounds were rapidly assimilated (>80% in 6 h). Both caused an initial 80% or greater increase in the intracellular glutamate pool and had similar effects in increasing the specific activities of NADP- and NAD-glutamate dehydrogenases and glutamine synthetase. Differences between the effects of added NH 4 + and glutamate showed that suppression was not correlated with intracellular pools of arginine or glutamine, nor was the maintenance of an elevated glutamate pool required to maintain the suppressed state. While a portion of the initial glutamate suppression could be attributed to an effect on central carbon metabolism through glutamate catabolism by NAD-glutamate dehydrogenase, the long term suppression by glutamate and the suppression by NH 4 + were more specific. Suppression by NH 4 + or glutamate in the presence or absence of protein synthesis (cycloheximide) followed essentially identical kinetics during 12 h. These results indicate that nitrogen additions cause a biochemical repression of enzymes associated with lignin degradation. Results are consistent with the hypothesis that nitrogen metabolism via glutamate plays a role in initiation of repression.

Ab initio studies of structural features not easily amenable to experiment: Part III. The influence of lone pair orbital interactions on molecular structure

Abstract: The characteristic structural asymmetries and distortions of AXYB systems in which an electron lone pair is at Y are discussed on the basis of the completely relaxed ab initio equilibrium geometries of a number of representative systems including various conformations of methanediol, hydrazine, 1,2-dimethylhydrazine and of compounds with CH 3 groups adjacent to OH, OCH 3 , NH, NCH 3 and C(π). It is found that, regardless of quantitative overlap and energy gap factors, all calculated trends in the relative extensions of bond distances and bond angles can be correlated in every detail to qualitative predictions based only on the orientational aspects of orbital interaction concepts.

Beach erosion as a function of variations in the sediment budget, Sandy Hook, New Jersey, U.S.A.

Abstract: Many of the world's beaches have recently been eroding, even on progradational landforms. This study uses the sediment budget approach to identify and rank the causes of the hazard along Sandy Hook spit where the primary recreational beach has been eroding at about 10 m/yr since 1953 and 23 m/yr in the 1970s. Large spatial variations in longshore sediment transport are found to result from differences in refracted wave energies and intersegmental sediment transport. Erosion results from a 60 per cent deficit (-270,000 m3/yr) in the sediment budget that is primarily caused by (1) refraction induced locally high waves that increase the transport rate by 100,000 m3, and (2) shore protection structures that have lessened the longshore sediment inputs by an additional 100,000 m3/yr. A storm index is presented to analyse secular climatic variation. It suggests that the annual sediment transport rate may vary by as much as ±50 per cent about the mean and that recently, above normal storm wave energies are responsible for about 60,000 m3/yr of the budget deficit. Rising sea levels and storm overwash each account for only about one per cent of the sediment loss. Pulses of sediment, induced by accelerated erosion at the feeder beach locale of spit segments, are found to move downdrift. They alter the geomorphology of the spit through episodic extensions of the spit segments with lag times exceeding one year per segment.

Ab initio studies of structural features not easily amenable to experiment: Part 8. The structural consequences of the anomeric effect in compounds with disubstituted tetrahedral carbon atoms

Abstract: The geometries of three conformations of FCH 2 OH and four conformations each of NH 2 CH 2 NH 2 and NH 2 CH 2 OH are completely refined by ab initio calculations on the 4–21G level. It is found that most characteristic structural and conformational properties of such systems can be reliably predicted on the basis of a simple anomeric orbital interaction model. The extension of this model to all compounds in which two electronegative substituents with non-bonding lone pairs or bonding π-electrons are attached to the same tetrahedral carbon atom, including polymer systems such as proteins, seems to be useful.

The Marketing of Legal Services

Abstract: This article takes a marketing analysis perspective of the distribution of legal services. A study of the demographic, personal, and life cycle characteristics of users and nonusers of legal services reveals that users are still primarily those with money and prestige. Some difference is found in the ways the two groups perceive important characteristics of lawyers for decision making purposes and in their perceptions of what potential legal needs are the most important. The problem of unevenness in the distribution system is seen as a marketing one. Suggestions as to how the delivery of services can be improved to present nonusers are made, based on market analysis.

Seasonal History and Indirect Flight Muscle Degeneration and Regeneration in the Rice Water Weevil

Abstract: Indirect flight muscles in the rice water weevil, Lissorhoptrus oryzophilus Kuschel, are greatly reduced in adults during winter. Muscle regeneration occurs in the spring just before adult exodus from overwintering sites. Once adults establish themselves in a flooded rice-field, the indirect flight muscles degenerate as females begin oviposition. First-generation adults possess well-developed indirect flight muscles; they exit fields in which they develop. Large numbers fly to aestivo-hibernation sites where muscle degeneration promptly occurs. Some first-generation adults move to young rice, if available, where muscle degeneration and oviposition occurs.

Use of Seasat satellite radar imagery for the detection of standing water beneath forest vegetation

Abstract: The Seasat synthetic aperture radar, operating at a 23-cm, L-band wavelength, detected anomalous tonal patterns in areas having relatively uniform vegetable canopy. These anomalously high radar returns were shown to be related more to the underlying terrain (areas of standing water) than to the vegetation canopy. These results show that L-band radars, imaging forested terrain in a Seasat configuration, are sensitive to gross changes in vegetation, and may even penetrate the vegetation canopy, providing an unmistakable radar signature. Properly designed space imaging radar shuttle experiments, using multiple frequency and polarization radars of various depression angles, may provide documentation for a flood-monitoring capability. Height, configuration, and density of the biomass in conjunction with frequency and incidence angle of the imaging system are shown to be important factors in formulating a backscatter model, but the relative significance of each is yet to be determined.

On the distinction between illogical and irrational beliefs and their relationship to anxiety

Abstract: To determine the relationship between dysfunctional cognitions and anxiety, 242 undergraduates completed the Irrational Beliefs Test, the Dysfunctional Attitudes Scale, and the State-Trait Anxiety Inventory. The former is said to measure Ellis' irrational beliefs and the latter is said to measure attitudes related to Beck's measure of depressed affect. While these two scores and the anxiety measures were all significantly correlated, a canonical correlation analysis showed that the relationship between measures of anxiety and of cognitive dysfunction could be almost entirely accounted for by the simple relationship between the score on irrational beliefs and Trait Anxiety.

Person-Computer Interface using Touch Screen Devices

Abstract: Within recent years, the advent of microprocessor technology and reduction in cost of optical electronic devices has allowed Touch Screen Devices (TSD's) to become a viable option for person-comput...

Effect of cocaine and lidocaine on the expression of kindled seizures in the rat

Abstract: The effect of cocaine and lidocaine on the expression of kindled seizures was studied in male Long-Evans rats. Animals were implanted with an electrode in either the olfactory bulb, prepyriform cortex, or basolateral amygdala and kindled by daily electrical stimulation. Each animal was then tested for the expression of kindled seizures following the intraperitoneal administration of saline, 20 mg/kg cocaine hydrochloride, or 20 mg/kg lidocaine hydrochloride. During testing the implantation site was stimulated every 60 sec at increasing current levels until an afterdischarge was elicited. Each animal was tested once under each drug at 96 hr intervals. The order of drug administration was counterbalanced across animals. Neither cocaine nor lidocaine had a significant effect on afterdischarge threshold. Both drugs significantly reduced the latency for clonus to occur following stimulation, a measure presumably related to the propagation of afterdischarges from the site of stimulation to other brain areas. In addition both cocaine and lidocaine significantly reduced the rated behavioral response to the stimulation due to a decrease in rearing and falling. Because they occurred with both cocaine and lidocaine, these effects appear to be of local anesthetic origin. In contrast, only cocaine significantly reduced afterdischarge duration, and only lidocaine significantly reduced clonus intensity. With the possible exception of clonus latency, these effects were present at all electrode sites studied. The results indicate that cocaine has pronounced effects on the expression of seizure activity in the olfactory forebrain, some of which are due to its local anesthetic action, and some not.

Influence of Immature Fruits on Strawberry Jam Quality and Storage Stability

Abstract: Jam was prepared from two strawberry cultivars, ‘Cardinal’ and A-5344, which were suited to once-over machine harvest. For jam manufacture, puree from ripe (R) and immature (IM) fruits were combined in the following blends: 25% R + 75% IM, 50% R + 50% IM, 75% R + 25% IM, and 100% R. Initially and after storage at 2°C for 6 and 12 months, jam color and flavor of all mixtures were acceptable. Jam made from 25 and 50% ripe fruit of A-5344 had unacceptable color after 6 and 12 months, respectively, at 25°C. All jam stored at 35°C was unacceptable after 6 months. Color acceptability was more dependent on total anthocyanin content than the percentage of ripe puree used in jam manufacture.

Participative Performance Appraisal Effects Upon Job Satisfaction, Agency Climate, and Work Values: Results of a Quasi-Experimental Study in Six State Agencies:

Abstract: Three matching pairs of test and control agencies were carefully selected for the assessment of a new participative performance appraisal system. The design for this pilot study evaluation was base...