University of Missouri

About: University of Missouri is a education organization based out in Columbia, Missouri, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 41427 authors who have published 83598 publications receiving 2911437 citations. The organization is also known as: Mizzou & Missouri-Columbia.

Water stress induced changes in concentrations of proline and total soluble sugars in nodulated alfalfa (Medicago sativd) plants

Abstract: Susceptibility of alfalfa (Medicago saliva L. cv. Aragon) nodules and leaves to water stress has been investigated. Nodule acetylene reduction activity (ARA), leaf CO2 exchange rate (CER) as well as soluble protein, proline and total soluble sugar (TSS) contents were determined during drought. Water status was estimated as water potential (Ψw) and Relative water content (RWC) of the respective tissues. Maximum rates of ARA required higher Ψw than CER. Nodules had lower RWC for a given Ψw than leaves. Water stress reduced soluble protein content in both tissues; however, the decline in soluble protein content was detected at greater Ψw in nodules than in leaves. Proline and TSS increased in leaves and nodules, and again the threshold Ψw triggering such accumulation was higher in nodule tissues. Oior results suggest that alfalfa nodules are more susceptible to water shortage than leaves. Effects of accumulated TSS and proline upon leaf and nodule physiology are discussed in relation to protein stability (proline), pH control (proline) and osmotic adjustment (proiine and TSS). The TSS accumulation induced by water stress suggests that substrate shortage would not be the primary effect of drought on nodule activity.

Basic psychological need satisfaction, need frustration, and need strength across four cultures

Abstract: The present study investigated whether satis- faction and frustration of the psychological needs for autonomy, relatedness, and competence, as identified within Basic Psychological Need Theory (BPNT; Deci and Ryan, Psychol Inquiry 11:227-268, 2000; Ryan and Deci, Psychol Inquiry 11:319-338, 2000), contributes to participants' well-being and ill-being, regardless of their cultural back- ground and interpersonal differences in need strength, as indexed by either need valuation (i.e., the stated importance of the need to the person) or need desire (i.e., the desire to get a need met). In Study 1, involving late adolescents from Belgium and China (total N = 685; Mean age = 17 years), autonomy and competence satisfaction had unique associations with well-being and individual differences in need valuation did not moderate these associations. Study 2 involved participants from four culturally diverse nations (Belgium, China, USA, and Peru; total N = 1,051; Mean age = 20 years). Results provided evidence for the mea- surement equivalence of an adapted scale tapping into both need satisfaction and need frustration. Satisfaction of each of the three needs was found to contribute uniquely to the prediction of well-being, whereas frustration of each of the three needs contributed uniquely to the prediction of ill- being. Consistent with Study 1, the effects of need satis- faction and need frustration were found to be equivalent across the four countries and were not moderated by indi- vidual differences in the desire for need satisfaction. These findings underscore BPNT's universality claim, which states that the satisfaction of basic needs for autonomy, relatedness, and competence represent essential nutrients for optimal functioning across cultures and across individ- ual differences in need strength.

Three keys to the radiation of angiosperms into freezing environments

Abstract: Early flowering plants are thought to have been woody species restricted to warm habitats 1–3 . This lineage has since radiated into almost every climate, with manifold growth forms 4 . As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing. To explore the evolution of traits underpinning the ability to persist in freezing conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to freezing). To model the evolution of species’ traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully move di nto freezingprone environments by either possessing transport networks of small

Multilevel Modeling of Individual and Group Level Mediated Effects.

Abstract: This article combines procedures for single-level mediational analysis with multilevel modeling techniques in order to appropriately test mediational effects in clustered data. A simulation study compared the performance of these multilevel mediational models with that of single-level mediational models in clustered data with individual- or group-level initial independent variables, individual- or group-level mediators, and individual level outcomes. The standard errors of mediated effects from the multilevel solution were generally accurate, while those from the single-level procedure were downwardly biased, often by 20% or more. The multilevel advantage was greatest in those situations involving group-level variables, larger group sizes, and higher intraclass correlations in mediator and outcome variables. Multilevel mediational modeling methods were also applied to data from a preventive intervention designed to reduce intentions to use steroids among players on high school football teams. This example illustrates differences between single-level and multilevel mediational modeling in real-world clustered data and shows how the multilevel technique may lead to more accurate results.