Purdue University

About: Purdue University is a education organization based out in West Lafayette, Indiana, United States. It is known for research contribution in the topics: Population & Heat transfer. The organization has 73219 authors who have published 163563 publications receiving 5775236 citations. The organization is also known as: Purdue & Purdue-West Lafayette.

Ion homeostasis in NaCl stress environments

Abstract: Homeostasis can be defined as the tendency of a cell or an organism to maintain internal steady state, even in response to any environmental perturbation or stimulus tending to disturb normality, because of the coordinate responses of its constituent components. Typically, ions constantly flux in and out of cells in a controlled fashion with net flux adjusted to accommodate cellular requirements, thus creating an ionic homeostasis. When plant cells are exposed to salinity, mediated by high NaCl concentrations, kinetic steady states of ion transport for Na+ and Cland other ions, such as K+ and Ca2+, are disturbed (Binzel et al., 1988). High apoplastic levels of Na+ and Clalter aqueous and ionic thermodynamic equilibria, resulting in hyperosmotic stress, ionic imbalance, and toxicity. Thus, it is vital for the plant to re-establish cellular ion homeostasis for metabolic functioning and growth, that is, to adapt to the saline environment. Comparisons of what have been interpreted to be adaptive responses among various species lead to the conclusion that some salt-tolerant plants have evolved specialized complex mechanisms that allow adaptation to saline stress conditions. In fact, these unique mechanisms, such as salt glands, exist in few plant species and cannot be presumed to be ubiquitously functional for salt adaptation of all plants. However, intrinsically cellular-based mechanisms appear to be common to all genotypes and are a requisite for salt tolerance. Of paramount importance are those mechanisms that function to regulate ion homeostasis while mediating osmotic adjustment through the accumulation and intracellular compartmentation of ions that are predominant in the external environment. In this update we will focus principally on Na+ homeostasis in sodic environments; however, we also include discussions of H+, K+, Ca2+, and Clbecause of the interrelationship of these ions with Na+ homeostasis. Ion transport processes across the plasma membrane and the tonoplast will be emphasized because these are presumed to be most essential for the control of intracellular Na+ uptake and vacuolar compartmentation.

Structure of gender stereotypes: Interrelationships among components and gender label.

Abstract: Various components of gender stereotypes were examined in three studies to determine their interrelationship and their influence relative to gender label. In the first two experiments, male and female college students were given information about gender and either role behaviors or traits and were asked to assess the probability that the stimulus person possessed other gender-related characteristics. In the third experiment, each of four gender stereotype components was presented in a within-subjects design and subjects made judgments about each other component. Results indicate that (a) information about one stereotype component can implicate other components; (b) specific component information may outweigh gender identification; and (c) components differ in their ability to implicate other components of gender stereotypes, with physical appearance playing a dominant role. The significance of these findings in understanding the structure and operation of gender stereotypes is discussed. Stereotypes play an important role in human judgment, and investigators have shown sustained interest in exploring the content and consequences of such judgments. From Lippman's (1922) early and insightful analysis of the "pictures in our heads," through the work of Katz and Braly (1933), Allport (1954), Campbell (1967) and others, stereotypes have continued to hold the interest of social scientists concerned with ways in which we judge and misjudge members of recognizable groups. In recent years, interest in the topic has accelerated, with new attention focused both on the general nature of stereotypes as well as on specific content categories (Hamilton, 1979, 1981; Miller, 1982). At the general level, investigators are increasingly coming to conceptualize stereotypes as one particular instance of more general cognitive processes (Ashmore D Hamilton, 1979;McCauley,