Showing papers by "Washington State University published in 1995"

Methane emissions from cattle.

Abstract: Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores to the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.

Soil microbial diversity and the sustainability of agricultural soils

Abstract: Many world ecosystems are in various states of decline evidenced by erosion, low productivity, and poor water quality caused by forest clearing, intensive agricultural production, and continued use of land resources for purposes that are not sustainable. The biological diversity of these systems is being altered. Little research has been conducted to quantify the beneficial relationships between microbial diversity, soil and plant quality, and ecosystem sustainability. Ecosystem functioning is governed largely by soil microbial dynamics. Differences in microbial properties and activities of soils have been reported but are restricted to general ecological enumeration methods or activity levels, which are limited in their ability to describe a particular ecosystem. Microbial populations and their responses to stresses have been traditionally studied at the process level, in terms of total numbers of microorganisms, biomass, respiration rates, and enzyme activities, with little attention being paid to responses at the community or the organismal levels. These process level measurements, although critical to understanding the ecosystem, may be insensitive to community level changes due to the redundancy of these functions. As microbial communities comprise complex interactions between diverse organisms, they should be studied as such, and not as a “black box” into which inputs are entered and outputs are received at measured rates. Microbial communities and their processes need to be examined in relation to not only the individuals that comprise the community, but the effect of perturbations or environmental stresses on those communities.

Linearity enhancement of multibit /spl Delta//spl Sigma/ A/D and D/A converters using data weighted averaging

Abstract: A dynamic element matching algorithm, data weighted averaging, is introduced for use in multibit /spl Delta//spl Sigma/ data converters. Using this algorithm, distortion spectra from DAC linearity errors are shaped by first-order noise shaping, resulting in a dynamic range improvement of 9 dB/octave when DAC errors dominate. Combining this technique with random dithering nearly eliminates the aliasing of the DAC errors into the baseband. Simulations show that with only 1% element matching 110 dB signal-to-noise ratio (18 b) is achieved for a third-order 3-b modulator with an oversampling ratio of 128.

Salicylic acid inhibits synthesis of proteinase inhibitors in tomato leaves induced by systemin and jasmonic acid

Abstract: Salicylic acid (SA) and acetylsalicylic acid (ASA), previously shown to inhibit proteinase inhibitor synthesis induced by wounding, oligouronides (H.M. Doherty, R.R. Selvendran, D.J. Bowles [1988] Physiol Mol Plant Pathol 33: 377-384), and linolenic acid (H. Pena-Cortes, T. Albrecht, S. Prat, E.W. Weiler, L. Willmitzer [1993] Planta 191: 123-128), are shown here to be potent inhibitors of systemin-induced and jasmonic acid (JA)-induced synthesis of proteinase inhibitor mRNAs and proteins. The inhibition by SA and ASA of proteinase inhibitor synthesis induced by systemin and JA, as well as by wounding and oligosaccharide elicitors, provides further evidence that both oligosaccharide and polypeptide inducer molecules utilize the octadecanoid pathway to signal the activation of proteinase inhibitor genes. Tomato (Lycopersicon esculentum) leaves were pulse labeled with [35S]methionine, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the inhibitory effects of SA are shown to be specific for the synthesis of a small number of JA-inducible proteins that includes the proteinase inhibitors. Previous results have shown that SA inhibits the conversion of 13S-hydroperoxy linolenic acid to 12-oxo-phytodienoic acid, thereby inhibiting the signaling pathway by blocking synthesis of JA. Here we report that the inhibition of synthesis of proteinase inhibitor proteins and mRNAs by SA in both light and darkness also occurs at a step in the signal transduction pathway, after JA synthesis but preceding transcription of the inhibitor genes.

Chloroplast gene sequence data suggest a single origin of the predisposition for symbiotic nitrogen fixation in angiosperms.

Abstract: Of the approximately 380 families of angiosperms, representatives of only 10 are known to form symbiotic associations with nitrogen-fixing bacteria in root nodules. The morphologically based classification schemes proposed by taxonomists suggest that many of these 10 families of plants are only distantly related, engendering the hypothesis that the capacity to fix nitrogen evolved independently several, if not many, times. This has in turn influenced attitudes toward the likelihood of transferring genes responsible for symbiotic nitrogen fixation to crop species lacking this ability. Phylogenetic analysis of DNA sequences for the chloroplast gene rbcL indicates, however, that representatives of all 10 families with nitrogen-fixing symbioses occur together, with several families lacking this association, in a single clade. This study therefore indicates that only one lineage of closely related taxa achieved the underlying genetic architecture necessary for symbiotic nitrogen fixation in root nodules.

Oligogalacturonides and chitosan activate plant defensive genes through the octadecanoid pathway.

Abstract: Jasmonic acid, synthesized from linolenic acid (the octadecanoid pathway), has been proposed to be part of a signal transduction pathway that mediates the induction of defensive genes in plants in response to oligouronide and polypeptide signals generated by insect and pathogen attacks. We report here that the induction of proteinase inhibitor accumulation in tomato leaves by plant-derived oligogalacturonides and fungal-derived chitosan oligosaccharides is severely reduced by two inhibitors (salicylic acid and diethyldi-thiocarbamic acid) of the octadecanoid pathway, supporting a role for the pathway in signaling by oligosaccharides. Jasmonic acid levels in leaves of tomato plants increased several fold within 2 hr after supplying the polypeptide systemin, oligogalacturonides, or chitosan to the plants through their cut stems, as expected if they utilize the octadecanoid pathway. The time course of jasmonic acid accumulation in tomato leaves in response to wounding was consistent with its proposed role in signaling proteinase inhibitor mRNA and protein synthesis. The cumulative evidence supports a model for the activation of defensive genes in plants in response to insect and pathogen attacks in which various elicitors generated at the attack sites activate the octadecanoid pathway via different recognition events to induce the expression of defensive genes in local and distal tissues of the plants.

Interactions between germ cells and Sertoli cells in the testis.

Abstract: The "nurse cell" function of Sertoli cells in spermatogenesis was originally tacitly assumed on the basis of the anatomical relationships between cells in the testis. In mammals, from very early in prenatal development to the onset of meiosis and to the ultimate production of spermatozoa, the relationship between the germinal cells and the Sertoli cells is important and apparently obligatory. The experimental evidence supports the notion that the primary endocrine regulation of spermatogenesis via FSH and testosterone is manifested through actions on the Sertoli cells. Although diverse strategies are used by Sertoli cells to support germ cell development, one of the most important roles of Sertoli cells is the regulation of the intratubular and intercellular environment adluminal to the tight junctional complexes. The meiotic and post-meiotic germ cells are sequestered by Sertoli-Sertoli junctional complexes in an adluminal compartment that is isolated from the serum or lymph. As a result of this sequestering activity, the secretion products of the Sertoli cells and the meiotic germ cells determine the composition of this local environment that can influence meiosis as well as spermatid and spermatocyte development. Evidence is accumulating that paracrine and autocrine factors from Sertoli and germ cells are important in the functioning of both cell types. While it is important to know what Sertoli cells and germ cells make, it is equally important to know when they make it. Distinct but well-defined groups of germ cells interact with Sertoli cells in a cyclic pattern. These recurring groups of germ cells define the cycle of the seminiferous epithelium during which sperm are produced in an asynchronous fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Your place or mine?: the effect of place creation on environmental values and landscape meanings

Abstract: The creation of place is predicated on two factors: (1) the social and cultural contexts in which people describe and define a space into a place and (2) the nature of a given space, much of which may not be readily recognizable or categorizable. This qualitative inductive analysis illustrates the concept of place creation through the voices of rural residents as they describe how they believe the resources within a local river drainage should be managed. The results of the interviews indicate that personal experience of a place can alter the values, beliefs, and wisdoms that individuals normally share with their primary social group. However, individuals may be reluctant to share their feelings of emotional ties to a place in traditional public involvement frameworks. Exposure of these conflicting values suggests the importance of using methodologies and public involvement programs conducive to expression of the creation of place.

Systemin activates synthesis of wound-inducible tomato leaf polyphenol oxidase via the octadecanoid defense signaling pathway.

Abstract: Tomato plants overexpressing a prosystemin gene that encodes the precursor of a mobile wound signal called systemin have been shown previously to constitutively synthesize extraordinarily high levels of two defensive proteinase inhibitor proteins in leaves in the absence of wounding. We herein report that leaves of these transgenic plants possess enhanced levels of another defensive protein, polyphenol oxidase (PPO) at levels that are up to 70-fold higher than levels found in leaves of wild-type plants. Supplying young wild-type tomato plants with systemin through cut stems induced PPO activity in leaves, and wounding lower leaves of young tomato plants induced PPO activity in both wounded and unwounded leaves to levels equal to those induced by systemin. Exposing young tomato plants to methyl jasmonate vapor caused an increase in PPO activity equivalent to levels found in plants overexpressing the prosystemin gene. The data indicate that PPO and proteinase inhibitor genes are coactivated systemically by wounding via the octadecanoid signal transduction pathway and that systemin has a much broader role in signaling plant defensive genes than was previously known.

Discordance between nuclear and chloroplast phylogenies in the heuchera group (saxifragaceae).

Abstract: Various factors, including taxon density, sampling error, convergence, and heterogeneity of evolutionary rates, can potentially lead to incongruence between phylogenetic trees based on different genomes. Particularly at the generic level and below, chloroplast capture resulting from hybridization may distort organismal relationships in phylogenetic analyses based on the chloroplast genome, or genes included therein. However, the extent of such discord between chloroplast DNA (cpDNA) trees and those trees based on nuclear genes has rarely been assessed. We therefore used sequences of the internal transcribed spacer regions (ITS-1 and ITS-2) of nuclear ribosomal DNA (rDNA) to reconstruct phylogenetic relationships among members of the Heuchera group of genera (Saxifragaceae). The Heuchera group presents an important model for the analysis of chloroplast capture and its impact on phylogenetic reconstruction because hybridization is well documented within genera (e.g., Heuchera), and intergeneric hybrids involving six of the nine genera have been reported. An earlier study provided a well-resolved phylogenetic hypothesis for the Heuchera group based on cpDNA restriction-site variation. However, trees based on ITS sequences are discordant with the cpDNA-based tree. Evidence from both morphology and nuclear-encoded allozymes is consistent with the ITS trees, rather than the cpDNA tree, and several points of phylogenetic discord can clearly be attributed to chloroplast capture. Comparison of the organellar and ITS trees also raises the strong likelihood that ancient events of chloroplast capture occurred between lineages during the early diversification of the Heuchera group. Thus, despite the many advantages and widespread use of cpDNA data in phylogeny reconstruction, comparison of relationships based on cpDNA and ITS sequences for the Heuchera group underscores the need for caution in the use of organellar variation for retrieving phylogeny at lower taxonomic levels, particularly in groups noted for hybridization.

The Effects of Emotional Arousal and Valence on Television Viewers' Cognitive Capacity and Memory.

Abstract: This study examines the combined effects of arousal and valence on viewers’ capacity allocation to and memory for television messages. Results show that when valence (how positive or negative a message is) is controlled, arousing messages are remembered better than calm messages. When arousal is controlled, positive messages are remembered better than negative messages. Reaction time results suggest that capacity allocation is a function of both valence and arousal. Viewers allocate the most capacity to positive arousing messages and the least capacity to negative arousing messages. The calm messages (both positive and negative) fall between these two.

Religion and crime reexamined: the impact of religion, secular controls, and social ecology on adult criminality*

Abstract: Since Hirschi and Stark's (1969) surprising failure to find religious (“hellfire”) effects on delinquency, subsequent research has generally revealed an inverse relationship between religiosity and various forms of deviance, delinquency, and crime. The complexity of the relationship and conditions under which it holds, however, continue to be debated. Although a few researchers have found that religion's influence is noncontingent, most have found support—especially among youths—for effects that vary by denomination, type of offense, and social and/or religious context. More recently the relationship has been reported as spurious when relevant secular controls are included. Our research attempts to resolve these issues by testing the religion-crime relationship in models with a comprehensive crime measure and three separate dimensions of religiosity. We also control for secular constraints, religious networks, and social ecology. We found that, among our religiosity measures, participation in religious activities was a persistent and noncontingent inhibiter of adult crime.

Fundamental aspects of controlled release in foods

Abstract: The fundamental equations governing the controlled release of active ingredients and the application of controlled-release technology in food systems are reviewed in this article. The method of microencapsulation, among others, can be applied to achieve controlled release in foods. Some of the release mechanisms employed in the food industry involve one or a combination of the following stimuli: a change in temperature, moisture or pH; the application of pressure or shear; and the addition of surfactants. Encapsulation is a method of protecting food ingredients that are sensitive to temperature, moisture, microorganisms or other components of the food system. Such food ingredients include flavors, sweeteners, enzymes, food preservatives and antioxidants, and are encapsulated using carbohydrates, gums, lipids and/or proteins. With a properly designed controlled-release delivery system, the food ingredient is released at the desired site and time at a desired rate.

The role of surface-active carbohydrates in the flocculation of a diatom bloom in a mesocosm

Abstract: A study was undertaken to evaluate the role of exocellular polysaccharides in the flocculation of a marine diatom bloom in a large tank mesocosm. Surface-active organic matter was extracted from 1.0 μ-filtered tank water by bubble adsorption each day for 7 days of the experiment. In agreement with past studies, particles (3–51 urn equivalent spherical diameter) were readily formed by bubbling and became concentrated in the foam. At the beginning of the bubbling (0–0.5 h), both particles and surface-active carbohydrates were extracted at high rates; however, these rates dropped off steeply after about 0.5 h of bubbling. The rate of particle formation by bubbling could be modeled fairly well by second order kinetics. The extracted, surface-active material was enriched in deoxysugars and galactose, while the residual material was enriched in glucose. Extracted surface-active carbohydrates reached a maximum of 33% of the total dissolved sugars ( 0.99) with particle stickiness (alpha). In addition, the concentration of surface-active carbohydrates was well correlated (2 = 0.91) with the concentration of transparent exopolymer particles (TEP) in the tank, and it was demonstrated that TEP could be copiously formed by bubbling of 1.0 μm-filered seawater. The finding of a highly surface-active, deoxysugar-rich polysaccharide material that can be rapidly (<0.5 h) and selectively extracted by bubble adsorption is significant, as it is apparent that this material played important roles in particle stickiness and TEP formation in the tank, and thus it may, at times, play similar roles in particle aggregation in the sea.

Global Concern for the Environment: Is Affluence a Prerequisite?

Abstract: It is widely assumed that public concern for environmental quality is dependent on affluence, and is therefore stronger in wealthy nations than in poor nations. This assumption is tested via results from a 1992 international survey conducted by the George H. Gallup International Institute that obtained data on a wide range of environmental perceptions and opinions from citizens in 24 economically and geographically diverse nations. Aggregate, national-level scores for a variety of measures of public concern for environmental quality were created and correlated with per capita gross national product. Although the results vary considerably depending upon the measure, overall national affluence is more often negatively rather than positively related to citizen concern for environmental quality—contradicting conventional wisdom.

Japanese and Local Partners Commitment to IJVs: Psychological Consequences of Outcomes and Investments in the IJV Relationships

Abstract: This study investigated the antecedents of commitment in IJVs from the major partners' perspective. Data were gathered from Japanese and local partners in IJVs located in eleven countries and analyzed in structural equations models. Results indicated that commitment is largely a function of the perceived benefits of the relationship, i.e., satisfaction and economic performance. However, exploration analyses of differences between local partners and the Japanese suggest that the effects of psychological antecedents might be contingent on the strategic intent of the relationship.

The dynamic nature of polyploid genomes

Abstract: It is well known that polyploidy is a major force in evolution, particularly in plants. Perhaps 50% of all angiosperms are of polyploid origin; estimates for the ferns and fern allies range from 44 to 95% (1, 2). Because of the significant role that it has played in plant evolution, polyploidy has been the focus of great interest and controversy for >50 years. Diverse aspects of polyploidy have been reviewed, including types of polyploids (3-8), ecological and evolutionary attributes of polyploids (810), genetic consequences of polyploid evolution (10-17), and mode of polyploid formation (4, 18, 19). The application of molecular techniques has dramatically increased our understanding of polyploid evolution and has fundamentally reshaped traditional views. The paper by Song et al. (20) in this journal further elucidates the process of polyploid evolution and represents a key breakthrough in our understanding of the evolution of polyploid genomes. To appreciate the great significance of the paper by Song et al. (20), it is important to consider briefly some of the traditional tenets of polyploid evolution.

Amphetamine produces sensitized increases in locomotion and extracellular dopamine preferentially in the nucleus accumbens shell of rats administered repeated cocaine.

Abstract: Alterations in dopamine transmission in the nucleus accumbens, which is composed of two anatomically distinct compartments termed the shell and core, contribute to the expression of cocaine-induced behavioral sensitization. To test potential presynaptic components of behavioral sensitization, the behavioral and neurochemical response to amphetamine administration in the accumbens shell and core was measured at early (days 1-3) and late (days 20-22) withdrawal in rats pretreated with systemic cocaine (15 mg/kg x 2 days, 30 mg/kg x 5 days) or saline. Behavioral sensitization was observed at late, but not early withdrawal when amphetamine was microinjected into the nucleus accumbens shell of cocaine-pretreated rats. There were no significant differences between cocaine- and saline-pretreated animals when behavior was monitored after amphetamine injections into the core at either withdrawal period. After both withdrawal periods, the amphetamine-induced increase in extracellular dopamine was potentiated among cocaine-pretreated animals in the shell by the local administration of amphetamine (0.03, 0.3, 3.0 and 30 microM through the dialysis probe). In the core at early withdrawal there was tolerance to the amphetamine-induced increase in extracellular dopamine in the cocaine group, whereas there was no difference between the repeated saline and cocaine groups at late withdrawal. In a second experiment designed to evaluate potential postsynaptic influences, the D1 partial agonist, SFK-38393 (0.01 or 0.1 microgram/side), was microinjected into the nucleus accumbens core or shell regions after behavioral sensitization to cocaine. Although there was a motor-stimulant effect of SKF-38393 at both withdrawal periods, there was no difference between rats pretreated with repeated cocaine or saline. Collectively, these results demonstrate that the augmentation in dopamine transmission in the nucleus accumbens that is associated with behavioral sensitization is more robust in the shell than the core.

Local bifurcations and feasibility regions in differential-algebraic systems

Abstract: The dynamics of a large class of physical systems such as the general power system can be represented by parameter-dependent differential-algebraic models of the form x/spl dot/=f and 0=g. Typically, such constrained models have singularities. This paper analyzes the generic local bifurcations including those which are directly related to the singularity. The notion of a feasibility region is introduced and analyzed. It consists of all equilibrium states that can be reached quasistatically from the current operating point without loss of local stability. It is shown that generically loss of stability at the feasibility boundary is caused by one of three different local bifurcations, namely the saddle-node and Hopf bifurcations and a new bifurcation called the singularity induced bifurcation which is analyzed precisely here for the first time. The latter results when an equilibrium point is at the singular surface. Under certain transversality conditions, the change in the eigenstructure of the system Jacobian at the equilibrium is established and the local dynamical structure of the trajectories near this bifurcation point is analyzed.

D1 receptors modulate glutamate transmission in the ventral tegmental area

Abstract: Perfusion of the D1 agonist, SKF-82958, through a microdialysis probe implanted in the ventral tegmental area produced a dose-dependent increase in extracellular glutamate and GABA. The increase in extracellular glutamate occurred at approximately 30x lower dose than the elevation in GABA. The increase in extracellular glutamate by SKF- 82958 was blocked by coperfusion of the D1 antagonist, SCH-23390, and was not mimicked by perfusion of the D2/3 agonist, quinpirole, into the ventral tegmental area. In contrast, the elevation in extracellular GABA was insensitive to blockade by SCH-23390. Systemic administration of cocaine (15 mg/kg, i.p.) produced a rapid elevation in extracellular glutamate lasting for 20 min that was prevented by pretreating the ventral tegmental area with SCH-23390. In contrast, acute cocaine produced a reduction in extracellular GABA content in the ventral tegmental area that was not affected by SCH-23390. These data indicate that the stimulation of D1 receptors in the ventral tegmental area increases the release of glutamate and that increasing extracellular levels of somatodendritic dopamine by systemic cocaine can mimic this effect.

Defining Audio/Video Redundancy From a Limited- Capacity Information Processing Perspective

Abstract: This article applies a limited-capacity information processing approach to the question of whether audio / video redundancy improves memory for television messages. Audio / video redundancy is defined as a continuum. Four different types of stimuli frequently used to operationalize redundancy are considered in terms of: (a) how much capacity they require to be fully processed; (b) how complex they are; and, (c) how much audio and video information they contain. Predictions based on these considerations are made about relative memory for each type of stimulus at three levels of processing (encoding, storage, and retrieval). The three major memory measures are conceptualized as providing information about different aspects of the information processing of a message. Specifically, recognition measures index how much information was encoded, cued recall indexes how much information has been stored, and free recall indexes the information available for retrieval. The predictions made using this theoretical app...

Central nervous system tumors.

Abstract: Central nervous system (CNS) tumors are relatively common in veterinary medicine, with most diagnoses occurring in the canine and feline species. Numerous tumor types from various cells or origins have been identified with the most common tumors being meningiomas and glial cell tumors. Radiation therapy is often used as an aid to control the clinical signs associated with these neoplasms. In general, these tumors have a very low metastatic potential, such that local control offers substantial benefit. Experience in veterinary radiation oncology would indicate that many patients benefit from radiation treatment. Current practice indicates the need for computed tomography or magnetic resonance imaging studies. These highly beneficial studies are used for diagnosis, treatment planning, and to monitor treatment response. Improvements in treatment planning and radiation delivered to the tumor, while sparing the normal tissues, should improve local control and decrease potential radiation related problems to the CNS. When possible, multiple fractions of 3 Gy or less should be used. The tolerance dose to the normal tissue with this fractionation schedule is 50 to 55 Gy. The most common and serious complications of radiation for CNS tumors is delayed radiation myelopathy and necrosis. Medical management of the patient during radiation therapy requires careful attention to anesthetic protocols, and medications to reduce intracranial pressure that is often elevated in these patients. Canine brain tumors have served as an experimental model to test numerous new treatments. Increased availability of advanced imaging modalities has spawned increased detection of these neoplasms. Early detection of these tumors with appropriate aggressive therapy should prove beneficial to many patients.

Expression of a type II collagen gene in the zebrafish embryonic axis

Abstract: To understand the hierarchy of developmental controls underlying axis specification in vertebrate embryos, it is helpful to identify relationships between regulatory molecules and the genes that given axial cells their differentiated phenotypes. This work reports the cloning and expression pattern of one of these differentiation genes, a type II collagen (col2a1) gene from the zebrafish Danio rerio. Along th8e embryonic axis, col2a1 is expressed dynamically in three rows that are each a single cell wide: the notochord and the rows of cells immediately dorsal and ventral to it—the floor plate of the central nervous system, and the hypochord. In addition, col2a1 is expressed in the pharyngeal arches, the epithelium of the otic capsule, and in the mesenchyme of the neurocranium. Experiments probed the expression pattern of col2a1 relative to that of known or potential regulators of axis development, including axial, sonic hedgehog, twist, and cyclops. The results showed that the spatial and temporal pattern of col2a1 expression in axial mesoderm follows the expression of twist closer than other genes tested. In cyclops embryos, which lack an intact floor plate, col2a1 expression was usually low, but not missing in cells in the ventral spinal cord. Because col2a1 expression reveals abnormalities in the notochord of cyclopsb16 embryos, and less col2a1-expressing mesenchyme accumulates rostral to the notochord in cyclops embryos, the effects of the cyclopsb16 mutation are not confined to the central nervous system. ©1995 Wiley-Liss, Inc.

Ecophysiology of Introduced Pennisetum Setaceum on Hawaii: The Role of Phenotypic Plasticity

Abstract: The C4 African grass, Pennisetum setaceum (fountaingrass), has a greater altitudinal distribution than any other grass on the island of Hawaii. Clones of P. setaceum were reciprocally transplanted among coastal dry grassland, montane dry shrubland, and subalpine dry forest sites on the leeward side of Hawaii to evaluate the contribution of local adaptation and individual tolerance to the broad ecological amplitude of this grass. Physiological, growth, and reproductive responses differed among sites without evidence of local adaptation. Greatest tiller production and the highest photosynthetic rates were observed at the mid-altitude site, but plants at the coastal site attained greater basal areas, aboveground biomass, and number of inflorescences. Correlation among the responses of different plant characters was environmentally dependent, suggesting that the integrated expression of these characters is also plastic. Few differences in plant responses, however, were attributable to a population's origin or the site-by-population interaction; resident populations and introduced populations responded similarly at each site. Furthermore, few characters exhibited variation among clones, indicating that these populations likely possess little genetic variation. Limited clonal variation was, however, detected for net photosyn- thesis, the ratio of internal to ambient CO2 concentration (C/Ca), and specific leaf area, but only on two of five dates over a 1-yr period. Phenotypic plasticity for both individual characters and the integration of physiological and morphological characters have appar- ently been most important in allowing P. setaceum to become dominant across diverse habitats on Hawaii.

Prevention of cell death induced by tumor necrosis factor alpha in LNCaP cells by overexpression of sulfated glycoprotein-2 (clusterin).

Abstract: Sulfated glycoprotein-2 (SGP-2) expression has been associated with programmed cell death in the prostate, but its exact role remains unclear. The present study was carried out in an attempt to establish the function of SGP-2 in programmed cell death using tumor necrosis factor (TNF) alpha-induced cytotoxicity in LNCaP cells as the model system. LNCaP is an androgen-sensitive, human prostatic cancer cell line that responds to TNF in culture by undergoing programmed cell death, as determined by the loss of cell number, failure to exclude trypan blue, detection of DNA fragmentation, and increased release of previously incorporated [3H]thymidine. Immunocytochemical staining for SGP-2 was weak but evident in LNCaP cells. Following treatment with TNF alpha, there was a time-dependent increase in SGP-2 staining, the intensity of which peaked at 2 h and declined thereafter. SGP-2 staining in LNCaP cells was undetectable prior to the onset of DNA fragmentation at 6 h of TNF treatment. This observation indicated that TNF-induced cell death in LNCaP cells was characterized by an initial transient elevation of SGP-2, followed by a period of SGP-2 depletion that preceded cell death. Transfection of LNCaP with a 21-base oligonucleotide antisense to SGP-2 resulted in a significant increase in cell death that was sequence specific and was accompanied by a reduction in SGP-2 biosynthesis. These findings supported the concept that SGP-2 depletion, rather than its expression, was associated with cell death. Finally, stable transfection and subsequent overexpression of SGP-2 in LNCaP cells resulted in resistance to the cytotoxic effect of TNF. These results have provided evidence to indicate that SGP-2 plays a role in the protection of TNF-induced cell death in LNCaP cells.