Iowa State University

About: Iowa State University is a education organization based out in Ames, Iowa, United States. It is known for research contribution in the topics: Population & Gene. The organization has 50151 authors who have published 107716 publications receiving 3355909 citations. The organization is also known as: Iowa State University of Science and Technology & Iowa State College.

Changes in Isozyme Profiles of Catalase, Peroxidase, and Glutathione Reductase during Acclimation to Chilling in Mesocotyls of Maize Seedlings.

Abstract: The response of antioxidants to acclimation and chilling in various tissues of dark-grown maize (Zea mays L.) seedlings was examined in relation to chilling tolerance and protection from chilling-induced oxidative stress. Chilling caused an accumulation of H2O2 in both the coleoptile + leaf and the mesocotyl (but not roots), and acclimation prevented this accumulation. None of the antioxidant enzymes were significantly affected by acclimation or chilling in the coleoptile + leaf or root. However, elevated levels of glutathione in acclimated seedlings may contribute to an enhanced ability to scavenge H2O2 in the coleoptile + leaf. In the mesocotyl (visibly most susceptible to chilling), catalase3 was elevated in acclimated seedlings and may represent the first line of defense from mitochondria-generated H2O2. Nine of the most prominent peroxidase isozymes were induced by acclimation, two of which were located in the cell wall, suggesting a role in lignification. Lignin content was elevated in mesocotyls of acclimated seedlings, likely improving the mechanical strength of the mesocotyl. One cytosolic glutathione reductase isozyme was greatly decreased in acclimated seedlings, whereas two others were elevated, possibly resulting in improved effectiveness of the enzyme at low temperature. When taken together, these responses to acclimation illustrate the potential ways in which chilling tolerance may be improved in preemergent maize seedlings.

The Influence of Neighborhood Disadvantage, Collective Socialization, and Parenting on African American Children's Affiliation with Deviant Peers

Abstract: This study focused on hypotheses about the contributions of neighborhood disadvantage, collective socialization, and parenting to African American children's affiliation with deviant peers. A total of 867 families living in Georgia and Iowa, each with a 10- to 12-year-old child, participated. Unique contributions to deviant peer affiliation were examined using a hierarchical linear model. Community disadvantage derived from census data had a significant positive effect on deviant peer affiliations. Nurturant/involved parenting and collective socialization processes were inversely associated, and harsh/inconsistent parenting was positively associated, with deviant peer affiliations. The effects of nurturant/involved parenting and collective socialization were most pronounced for children residing in the most disadvantaged neighborhoods.

Genomewide comparative analysis of alternative splicing in plants

Abstract: Alternative splicing (AS) has been extensively studied in mammalian systems but much less in plants. Here we report AS events deduced from EST/cDNA analysis in two model plants: Arabidopsis and rice. In Arabidopsis, 4,707 (21.8%) of the genes with EST/cDNA evidence show 8,264 AS events. Approximately 56% of these events are intron retention (IntronR), and only 8% are exon skipping. In rice, 6,568 (21.2%) of the expressed genes display 14,542 AS events, of which 53.5% are IntronR and 13.8% are exon skipping. The consistent high frequency of IntronR suggests prevalence of splice site recognition by intron definition in plants. Different AS events within a given gene occur, for the most part, independently. In total, 36–43% of the AS events produce transcripts that would be targets of the non-sense-mediated decay pathway, if that pathway were to operate in plants as in humans. Forty percent of Arabidopsis AS genes are alternatively spliced also in rice, with some examples strongly suggesting a role of the AS event as an evolutionary conserved mechanism of posttranscriptional regulation. We created a comprehensive web-interfaced database to compile and visualize the evidence for alternative splicing in plants (Alternative Splicing in Plants, available at www.plantgdb.org/ASIP).

Natural Orbitals in the Quantum Theory of Two-Electron Systems

Abstract: The wave functions for the singlet and triplet states of a two-electron system in a given nuclear framework are investigated as superpositions of configurations and are shown to be transformationally equivalent to quadratic forms having certain ranks and signatures. By introducing the "natural orbitals" diagonalizing the generalized first-order density matrix, the total wave functions may also be brought to principal form. If the basis contains $M$ one-electron functions, the singlet and triplet wave functions contain respectively $\frac{M(M+1)}{2}$ and $\frac{M(M\ensuremath{-}1)}{2}$ configurations, but the transformation to natural orbitals reduces the number of terms to $M$ and [$\frac{M}{2}$], respectively. The natural expansion having the best convergence is also characterized by another important extremum property. The approximate wave function of rank $r$ having the smallest quadratic deviation from the exact eigenfunction is obtained by interrupting the natural expansion of the eigenfunction after $r$ terms and renormalizing the result. For the singlet state, the wave function of rank two and signature zero has a special importance as giving a simple extension of the visual one-electron picture to include a large part of the correlation effects. The theory is illustrated by some results on helium obtained by using radial configuration interaction.

Family economic stress and adjustment of early adolescent girls.

Abstract: A family process model is proposed that links economic stress in family life to prosocial and problematic adolescent adjustment. With a sample of 220 7th-grade girls living in intact families in the rural Midwest, the theoretical constructs in the model were measured using both trained observer and family member reports. In general, results were consistent with the proposed model. Economic pressures led to depression and demoralization for both parents, the result of which was greater marital conflict and disruptions in skillful parenting. The emotions and behaviors of both mothers and fathers were almost equally affected by financial difficulties, and disruptions in eac parent's child-rearing behaviors had adverse consequences for adolescent development. Parents' depressed mood and disrupted child-rearing practices both directly affected girls' adjustment