Wilfred Vermerris, Karen Thompson, Lauren McIntyre, John Axtell; Evidence for an evolutionarily conserved interaction between cell wall biosynthesis and flowering in maize and sorghum: (in English) AbstractBackgroundFactors that affect flowering vary among different plant species, and in the grasses in particular the exact mechanism behind this transition is not fully understood. The brown midrib (bm) mutants of maize (Zea mays L.), which have altered cell wall composition, have different flowering dynamics compared to their wild-type counterparts. This is indicative of a link between cell wall biogenesis and flowering. In order to test whether this relationship also exists in other grasses, the flowering dynamics in sorghum (Sorghum bicolor (L.) Moench) were investigated. Sorghum is evolutionarily closely related to maize, and a set of brown midrib (bmr) mutants similar to the maize bm mutants is available, making sorghum a suitable choice for study in this context.ResultsWe compared the flowering time (time to half-bloom) of several different bmr sorghum lines and their wild-type counterparts. This revealed that the relationship between cell wall composition and flowering was conserved in sorghum. Specifically, the mutant bmr7 flowered significantly earlier than the corresponding wild-type control, whereas the mutants bmr2, bmr4, bmr6, bmr12, and bmr19 flowered later than their wild-type controls.ConclusionThe change in flowering dynamics in several of the brown midrib sorghum lines provides evidence for an evolutionarily conserved mechanism that links cell wall biosynthesis to flowering dynamics. The availability of the sorghum bmr mutants expands the germplasm available to investigate this relationship in further detail. [Text] [View with Perseus links] (0.60)
Gore, Jeffrey; Bollworm (Lepidoptera: Noctuidae) Ecology on Genetically Engineered Bollgard and Bollgard II Cottons: (in English) The ecology of bollworms, Helicoverpa zea (Boddie), on Bollgard and Bollgard II cottons, Gossypium hirsutum L., was studied in field and laboratory experiments. Neonate bollworm larvae were placed on selected components of cotton squares and flowers from non-Bollgard, Bollgard, and Bollgard II cotton varieties. Larval survival was higher on flower anthers and square anthers than on other floral parts for each cultivar. Bollworm survival was lowest on all Bollgard II floral structures. To evaluate larval behavior on Bollgard cotton, first instar bollworms were placed on terminals of non-flowering and flowering cotton plants. Larvae were recovered lower on Bollgard cotton than on non-Bollgard cotton. Larvae remained near the terminals of non-Bollgard plants feeding on terminal foliage and squares. On Bollgard cotton, more larvae were recovered from white flowers and bolls. To quantify injury from bollworms on Bollgard and Bollgard II cottons, first instar larvae were placed in white flowers of non-Bollgard, Bollgard, and Bollgard II cottons. Bollworms damaged approximately two and three times more fruiting forms on non-Bollgard cotton than on Bollgard and Bollgard II cottons, respectively. To evaluate the influence of alternate hosts on bollworm sensitivity to non-Bollgard and Bollgard cottons, host colonies were established on field corn, Zea mays L.; grain sorghum, Sorghum bicolor (Moench); soybean, Glycine max (Merrill); non-Bollgard cotton; and meridic diet. Field corn and grain sorghum were better hosts for bollworms than cotton. Neonates from each colony were placed on terminal foliage from non-Bollgard and Bollgard cottons in petri dishes. Mortality of larvae from the cotton colony was higher than mortality from the soybean, corn, and meridic diet colonies on non-Bollgard cotton. Mortality from the corn colony was higher than from the soybean and grain sorghum colonies on Bollgard cotton. Differences in bollworm larval behavior and development on Bollgard cotton suggest that changes are needed in the scouting protocols and management decisions for bollworms on Bollgard cotton compared to those on non-Bollgard cotton. Insecticide applications will be needed for bollworms on Bollgard cotton when populations persist over extended periods of time or when other boll feeding pests are present. Furthermore, alternate hosts may influence bollworm management with Bollgard cotton. [Text] [View with Perseus links] (3.00)
Castro, Boris A.; Evaluation of <i>Bacillus thuringiensis</i> Transgenic Field Corn for Management of Louisiana Corn Pests: (in English) Efficacy of <i>Bt</i> corn hybrids expressing an insecticidal delta-endotoxin through different transformation events was evaluated in Louisiana. Efficacy levels were determined for southwestern corn borer (SWCB), <i>Diatraea grandiosella</i> Dyar; sugarcane borer (SCB), <i>Diatraea saccharalis</i> (F.); corn earworm (CEW), <i>Helicoverpa zea</i> (Boddie); and fall armyworm (FAW), <i>Spodoptera frugiperda</i> (J. E. Smith). Insect (neonates and third instars) susceptibility was evaluated on <i>Bt</i> and non-<i>Bt</i> corn plants (V6 and R1 stages) in field plots and plant tissue in laboratory studies. <i>Bt</i> corn hybrids with MON810 and CBH351 transformation events sustained significantly (<I>P</I> < 0.05) less injury caused by SWCB, SCB, and FAW during infestations at mid-whorl stage. SWCB, SCB, and CEW infestations during silking stage were significantly reduced in <i>Bt</i> hybrids with the MON810 event. However, CEW infestations at silking stage were not significantly (<I>P</I> > 0.05) reduced in the <i>Bt</i> hybrid with the CBH351 event compared to respective non-<i>Bt</i> equivalent hybrid. Performance of BT11 and 176 events against CEW infestations at silking stage was not consistent under observed field conditions. SWCB and SCB were highly susceptible to the MON810 event in leaf tissue experiments. However, consistency in performance of the MON810 event against SWCB and SCB varied among <i>Bt</i> hybrids containing that event. SCB expressed less susceptibility to leaf tissue containing the CBH351 event than to leaf tissue with the MON810 event. Plant resistance to SWCB and SCB attack increased as plants matured, independent of the presence of a <i>Bt</i> construct. Higher CEW survival was observed on <i>Bt</i> silks than on <i>Bt</i> leaves regardless of <i>Bt</i> event. Economic returns above technology fee were consistently observed in central and most areas of northeast Louisiana. Economic returns in northwest Louisiana were highly dependent on corn market prices. Under growing conditions and investment levels observed, soybeans and in some cases grain sorghum production might offer higher economic benefits compared to <i>Bt</i> corn production for late-crop planting in some areas of Louisiana. [Text] [View with Perseus links] (0.93)
Overbeck, Gatewood Folger., New York (State).--State university, Albany.--Dept. of Classics.; Graves and burial customs at Ayia Irini, Kea,--by Gatewood Folger Overbeck.: Microfilm copy of typescript. 1 reel. 35 mm., Thesis--State University of New York at Albany. Dept. of History., Bibliography: leaves vii-xiii. [Text] (10.80)
Holtzer, Thomas Oliver,--1947-; Factors affecting the time required for emergence of diapausing Heliothis zea (Boddie) (Lepidoptera: Noctuidae) /--by Thomas O. Holtzer.: Vita., Thesis--North Carolina State University., Bibliography: leaves 46-49., Effects of various temperature regimes on the time required for emergence of diapausing Heliothis zea (Boddie).--Geographic and genetic variation in time required for emergence of diapausing Heliothis zea (Boddie). [Text] (6.46)
Feldman, Lewis Jeffrey.; The quiescent center in roots of Zea mays L. /--by Lewis Jeffrey Feldman.: Microfilm of typescript., Thesis--Harvard University., Bibliography: p. 124-132. [Text] (4.95)
Keate, George, 1729-1797.; The Monument in Arcadia. .: Preliminaries omitted., Transcribed from : The poetical works of George Keate. London : Printed for J. Dodsley [etc.], 1781., Available for non-commercial, internal use by students, staff, and faculty for academic and research purposes only., English verse drama database. Cambridge, England : Chadwyck-Healey Ltd., 1994. [Text] [View with Perseus links] (3.77)
Jagannathan, Murali; Internal Control Mechanisms and Forced CEO Turnover: An Empirical Investigation: John M. Pinkerton, Dilip K. Shome, Arthur J. Keown, Robert S. Hansen, Diane K. Denis; (in English) The dissertation empirically examines the efficacy of internal control mechanisms by analyzing 94 forced turnovers of chief executive officers (CEOs). It seeks to answer two primary questions: One, do governance-related characteristics influence the promptness with which poorly-performing CEOs are removed from office; and two, are removals of CEOs followed by changes in internal control mechanisms? The results suggest that poorly performing managers are removed more quickly in firms that have a larger percentage of independent outside directors on their board, that have higher equity ownership by the non-CEO directors and lower equity ownership by the CEO, and that separate the positions of CEO and chairperson. The results also suggest that the removal of the CEO provides both the opportunity and the incentive to alter internal governance systems. There is significant turnover of board members and the new boards generally have a higher fraction of independent outside directors and are more likely to separate the positions of CEO and chairperson. In addition, the sensitivity of CEO compensation to firm performance increases significantly following turnover. These post-turnover improvements in monitoring and incentive schemes are more significant in those firms that require a crisis in the product and/or capital market before they remove their CEOs. However, there is no evidence of short-term improvement in operating performance following changes in CEOs and governance systems. Overall, the results suggest that board and ownership characteristics do influence the effectiveness of internal monitoring systems and that CEO turnover is associated with broad changes in monitoring and incentive systems. [Text] [View with Perseus links] (5.86)
King, Steve Russell; Double-crop corn (zea mays) weed control in Virginia: Dr. E.S. Hagood, Dr. D.E. Brann, Dr. H.P. Wilson; (in English) Double-crop production of corn (Zea mays L.) for grain following the harvest of small grain is not currently practiced in Virginia. Historical precipitation and evapotransportation data indicate that delayed corn planting could result in a higher probability of moisture during critical periods of crop development. Double-crop corn may also reduce economic risk as two crops would be harvested in the same year. Field experiments were conducted in three Virginia locations in 1998 and 1999 to determine the herbicide inputs required for double-crop corn production relative to those required in full-season no-till corn production. Experiments were conducted in a split-plot, randomized complete block design with cropping system as the main plot and herbicide treatment as the subplot. Herbicide treatments included combinations of nonselective herbicides for no-till establishment and/or preemergence residual herbicides and/or selective postemergence herbicides in both production systems. Glyphosate-tolerant corn was planted in all experiments and postemergence glyphosate treatments were also evaluated. In each experiment, dependent variables included weed control by species evaluated throughout the season, as well as weed biomass and corn yield evaluated at the end of the growing season. Generally, nonselective herbicides were not required in the double-crop system where atrazine was applied as a preemergence treatment, or where selective postemergence treatments were applied. Where a significant proportion of the infestation was comprised of perennial species, however, atrazine treatments were not sufficient in the double-crop system. Postemergence glyphosate treatments provided excellent broad-spectrum weed control in this situation. In heavy annual grass infestations, postemergence glyphosate treatments provided superior weed control to preemergence treatments alone, and equivalent weed control to treatments in which both preemergence and postemergence herbicides were applied. Corn yield response to weed control and cropping system variables varied significantly between the 1998 and 1999 growing seasons. Where adequate late-season rainfall was received, economic return from small grain and corn crops in the double-crop system was higher than the return in the full-season system, particularly in infestations where the double-crop system allowed significant reduction in herbicide input. [Text] [View with Perseus links] (1.37)
Blanchard, David Joseph; Characterization of a Beta-glucosidase Aggregating Factor Responsible for the Null Beta-glucosidase Phenotype in Maize (Zea mays L.): William Newton, Charles Rutherford, Asim Esen; (in English) Beta-Glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) catalyzes the hydrolysis of aryl and alkyl beta-D-glucosides as well as glucosides with a carbohydrate moiety such as cellobiose and other beta-linked oligosaccharides. In maize (Zea mays L.), beta-glucosidase exists as 120 kD homodimers, but also forms high-molecular-weight (HMW) aggregates in certain maize inbreds (nulls). In this study we show that the null beta-glucosidase phenotype is caused by the formation of HMW enzyme aggregates (>1.5 X 106 Daltons), caused by a beta-glucosidase aggregating factor (BGAF). BGAF is a 32 kD protein that binds specifically to beta-glucosidase and renders it insoluble during extraction. The data unequivocally demonstrate that BGAF is solely responsible for beta-glucosidase aggregation and insolubility, and thus, the apparent null phenotype. Additionally, I have isolated the cDNA encoding BGAF and have identified BGAF as a member of the small heat-shock protein (sHsp) family. <p>Interestingly, BGAF binds to both maize beta-glucosidase isozymes (Glu1 and Glu2), but does not bind to their sorghum homolog Dhurrinase-1 (Dhr1; Sorghum beta-glucosidase), that shares 70% sequence identity with Glu1 and Glu2. Therefore, these proteins provide an excellent system to study functional differences at nonconserved residues and elucidate the mechanism of enzyme aggregation and insolubility. By examining the behavior of beta-glucosidase chimeras in binding assays, I demonstrate that BGAF binding is conformation dependent, highly specific, and reminiscent of antigen-antibody interactions. Additionally, I have identified two disparate polypeptide segments in the primary structure of the maize beta-glucosidase isozyme Glu1 that form a BGAF binding site in the tertiary structure of the enzyme. [Text] [View with Perseus links] (1.01)
Krisciunas, K.; Optical Night-Sky Brightness at Mauna Kea over the Course of a Complete Sunspot Cycle: We have produced a data base of V-band and B-band night-sky brightness measurements rather evenly spread out over the course of a whole sunspot cycle from September 1985 to August 1996. Almost all the data were obtained at the 2800-m level of Mauna Kea using the same telescope, same photomultiplier tube, filters, and diaphragm, thus minimizing various sources of systematic error and allowing an estimate of the sources of random error. The yearly V-band averages of observed sky brightness ranged from 21.287 to 21.906 magnitudes per square arc second. The color of the sky is $B-V$ = 0.930 and does not change discernibly over the course of the sunspot cycle. After correcting the V-band data to the zenith, we find that the airglow component varied a factor of 4.5 over the course of the solar cycle. Once the 11-year solar cycle effect is removed from the data, the most significant contribution to the scatter of individual data points appears to be the short term variations on time scales of tens of minutes like those observed by the Whole Earth Telescope project., Comment: 27 pages AAS-style (v 4.0) Latex, 5 figures, to be published in Publications of the Astronomical Society of the Pacific [Text] [View with Perseus links] (1.30)
... ; The Epoch of Major Star Formation in High-z Quasar Hosts: We present the results of our observing program on near infrared spectroscopy of high-redshift quasars which have been undertaken both at Kitt Peak National Observatory and at Mauna Kea Observatory, University of Hawaii. These data are utilized for studying the epoch of major star formation in high-redshift quasar hosts., Comment: 7 Latex (lamuphys.sty) pages including 2 PostScript figures. To appear in the Proceedings of Quasar Hosts held at Tenerife, Spain (September 24-27, 1996) [Text] [View with Perseus links] (0.77)