Dosage Effect at the Sugary-2 Locus on Maize Starch Structure and Function.

Structural characteristics and functional properties of starches isolated from kernels of a sugary-2 (su2) dosage series were examined to determine whether the normal allele (Su2) was completely dominant to the recessive allele (su2). Differential scanning calorimetry revealed intermediate values for gelatinization onset, gelatinization peak, range, total enthalpy, and retrogradation among genotypes possessing one and two mutant su2 alleles. No effect of gene dosage on amylose content was observed, but X-ray diffraction patterns revealed an intermediate degree of crystallinity relative to normal and mutant genotypes upon addition of two su2 alleles. Development of a peak at 19 degrees 2(theta) became more evident upon increasing doses of the su2 allele. Viscosity of the starch paste and gel strength resulting from the genotype possessing two doses of the su2 allele exceeded that of both mutant and normal genotypes. An intermediate retrogradation as detected by differential scanning calorimetry and from gel strengths of starches after storage for seven days suggested an increased stability of the Su2su2su2 starch relative to that of normal starch

Properties of Sugary-2 Maize Starch: Influence of Exotic Background.

Genetic modifiers of maize (Zea mays L.) starch thermal properties were examined by differential scanning calorimetry (DSC). Sugary- 2 (su2) kernels from segregating ears were identified based on textural appearance of starches following crosses between an exotic maize accession with the inbred OH43 homozygous for the su2 allele (OH43 su2). Two exotic maize accessions, PI213768 and PI451692, were used. Germs retained from su2 kernels were used to produce an F2 population of su2 plants containing 50% exotic germ plasm. With few exceptions, F2 ears from the populations were homozygous for the su2 allele. Significant (P less than or equal to 0.05) differences were seen between the exotic populations and OH43 su2 for gelatinization onset temperature (To), range (RN), enthalpy (deltaH), and retrogradation (%R). The number of DSC values with significant within-population variations was greater among F2 ears within the exotic populations than among ears within the inbred line OH43 su2. Standard deviations for DSC values were consistently greater for exotic su2 populations than for those of OH43 su2. Also, the population PI213768 su2 differed greatly from OH43 su2 for mean values of To, RN, deltaH, and %R (52.8 C, 13.4 C, 1.5 cal/g, and 34.5%, respectively) when compared to those of OH43 su2 (54.6 C, 10.6 C, 1.3 cal/g, and 29%, respectively). Results from this study indicate that examining the texture of starches from single kernels may be used to identify and develop populations homozygous for the su2 allele. In addition, the increased variability for DSC values within populations containing 50% exotic germ plasm suggest that genetic modifiers might be used to alter thermal properties and, possibly, functional properties of su2 starch

Effect of Planting Date on Maize Starch Thermal Properties.

Starches isolated from kernels of two maize (Zea mays L.) inbreds and their F1 progeny, grown after four planting dates, were evaluated for differences in thermal properties. Differential scanning calorimetry (DSC) was used to compare onset (To) and peak (Tp) temperature, range (Rn), and total enthalpy ((Delta)H) values of gelatinization. Amylose content (%AM) of samples was determined colorimetrically, and image analysis was used to determine average diameters of granules. Significant (P less than or equal to 0.05) increases for Tp and (Delta)H were observed with later planting dates. Significant genotypic differences also were seen for To, Tp, and (Delta)H. Later planting dates had no effect on %AM or starch granule size. Genotypes ranked similarly for %AM across each environment, and no differences were observed for average granule diameter. The presence of environmental effects on thermal properties of the starch suggests that if small differences (1-2 C or less than 0.2-0.3 cal/g) are to be identified among nonmutant genotypes, growing conditions may need to be controlled

Assay of Therapeutic Doses of Methotrexate in Body Fluids of Patients with Psoriasis

A microbiologic technique for the assay of methotrexate (MTX) in urine, serum, erythrocytes, feces, and skin is described. The accuracy of the method equals that of routine microbiologic assays of folic acid. Important differences in serum MTX levels in psoriatic patients during the 24 hr after standardized intravenous and intramuscular administration were demonstrated. Repeated intravenous doses tended to be cleared from the blood uniformly.After oral doses many patients achieved peak serum levels within 2 hr, with fall of level by 4 hr. Others achieved lower levels and responded less well clinically. Persistence of high serum levels at 24 and 48 hr did not confer obvious clinical benefit or necessarily give rise to toxicity. The pattern of clearance from serum was not influenced by serum albumin levels or by renal function when the creatinine clearance was greater than 50 mI/min. However, impaired renal function was clearly correlated with slow clearance.Routine measurement of MTX blood levels is of value in patients with suspected malabsorption or partial renal failure

Genome-wide association study for oat (Avena sativa L.) beta-glucan concentration using germplasm of worldwide origin

Detection of quantitative trait loci (QTL) controlling complex traits followed by selection has become a common approach for selection in crop plants. The QTL are most often identified by linkage mapping using experimental F2, backcross, advanced inbred, or doubled haploid families. An alternative approach for QTL detection are genome-wide association studies (GWAS) that use pre-existing lines such as those found in breeding programs. We explored the implementation of GWAS in oat (Avena sativa L.) to identify QTL affecting β-glucan concentration, a soluble dietary fiber with several human health benefits when consumed as a whole grain. A total of 431 lines of worldwide origin were tested over 2 years and genotyped using Diversity Array Technology (DArT) markers. A mixed model approach was used where both population structure fixed effects and pair-wise kinship random effects were included. Various mixed models that differed with respect to population structure and kinship were tested for their ability to control for false positives. As expected, given the level of population structure previously described in oat, population structure did not play a large role in controlling for false positives. Three independent markers were significantly associated with β-glucan concentration. Significant marker sequences were compared with rice and one of the three showed sequence homology to genes localized on rice chromosome seven adjacent to the CslFgene family, known to have β-glucan synthase function. Results indicate that GWAS in oat can be a successful option for QTL detection, more so with future development of higher-density markers

Prevalence and patterns of higher-order drug interactions in Escherichia coli.

Interactions and emergent processes are essential for research on complex systems involving many components. Most studies focus solely on pairwise interactions and ignore higher-order interactions among three or more components. To gain deeper insights into higher-order interactions and complex environments, we study antibiotic combinations applied to pathogenic Escherichia coli and obtain unprecedented amounts of detailed data (251 two-drug combinations, 1512 three-drug combinations, 5670 four-drug combinations, and 13608 five-drug combinations). Directly opposite to previous assumptions and reports, we find higher-order interactions increase in frequency with the number of drugs in the bacteria's environment. Specifically, as more drugs are added, we observe an elevated frequency of net synergy (effect greater than expected based on independent individual effects) and also increased instances of emergent antagonism (effect less than expected based on lower-order interaction effects). These findings have implications for the potential efficacy of drug combinations and are crucial for better navigating problems associated with the combinatorial complexity of multi-component systems

Women Leaders within Higher Education in the United States: Supports, Barriers, and Experiences of Being a Senior Leader

Fundamental change is underway in higher education requiring more leaders and a different type of leadership at all levels. However, statistics indicate the women are under represented at the senior-most levels. Our research focused on 35 women at the senior-most levels of institutions of higher education and explored their journey into senior leadership roles and their experience of being a leader in higher education today. Semi-structured interviews were conducted, coded, and analyzed. Included is a statistical comparison of the experiences of white women and women of color. This research contributes to a deeper understanding of the experiences of women in senior leadership positions in higher education. The women leaders in this study provide more detailed descriptions of the positive aspects of being in a leadership role than have been previously reported. The positive aspects of being in a leadership role are important to document in order to provide balanced perspective on the experiences of being a senior leader and a woman in higher education