328 research outputs found
Aphid resistance in wheat varieties
As an environmentally compatible alternative to the use of conventional insecticides to control cereal aphids, we have investigated the possibility to exploit natural resistance to insect pests in wheat varieties. We have tested a wide range of hexaploid (Triticum aestivum), tetraploid (T. durum) and diploid (T. boeoticum and T. monococcum) wheat lines for resistance to the bird cherry oat aphid (Rhopalosiphum padi). Lines tested included Russian wheat aphid (Diuraphis noxia), greenbug (Schizaphis graminum), hessian fly (Mayetiola destructor) and orange wheat blossom midge (Sitodiplosis mosellana) resistant varieties. Antixenosis and antibiosis were determined in the settling and fecundity tests respectively. Since hydroxamic acids (Hx), including the most generally active, 2,4-dihidroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), are biosynthesised in many cereal plants and are implicated in resistance against insects, leaf tissue was analysed for Hx and the glucosides from which they are produced. The hexaploid varieties, which contained relatively low levels of the DIMBOA glucoside, did not deter aphid feeding or reduce nymph production significantly. Reduced settlement and nymph production were recorded on the diploid varieties, but they contained no detectable level of the glucoside or the toxic aglucone
Cercospora beticola toxins. Part XVII. The role of beticolin/Mg2+ complexes in their biological activity. Study of plasma membrane H+-ATPase, vacuolar H+-PPase, alkaline and acid phosphatases
Beticolin-1 and beticolin-2, yellow toxins produced by the phytopathogenic fungus Cercospora beticola, inhibit the plasma membrane H+-ATPase. Firstly, since beticolins are able to form complexes with Mg2+, the role of the beticolin/Mg2+ complexes in the inhibition of the plasma membrane proton pump has been investigated. Calculations indicate that beticolins could exist under several forms, in the H+-ATPase assay mixture, both free or complexed with Mg2+. However, the percentage inhibition of the H+-ATPase activity is correlated to the concentration of one single form of beticolin, the dimeric neutral complex Mg2H2B2, which appears to be the active form involved in the H+-ATPase inhibition. Secondly, since previous data suggested that beticolins could also be active against other Mg2+-dependent enzymes, we tested beticolin-1 on the vacoular H+-PPase, which requires Mg2+ as co-substrate, and on the alkaline and acid phosphatases, which do not use Mg2+ as co-substrate. Only vacuolar H+-PPase is sensitive to beticolin-1, which suggests that beticolins are specific to enzymes that use a complex of Mg2+ as the substrate. The same Mg2H2B2 complex which is responsible of the plasma membrane H+-ATPase inhibition appears to be also involved in the inhibition of the vacuolar H+-PPase
Colorectal cancer liver metastatic growth depends on PAD4-driven citrullination of the extracellular matrix
Citrullination of proteins, a post-translational conversion of arginine residues to citrulline, is recognized in rheumatoid arthritis, but largely undocumented in cancer. Here we show that citrullination of the extracellular matrix by cancer cell derived peptidylarginine deiminase 4 (PAD4) is essential for the growth of liver metastases from colorectal cancer (CRC). Using proteomics, we demonstrate that liver metastases exhibit higher levels of citrullination and PAD4 than unaffected liver, primary CRC or adjacent colonic mucosa. Functional significance for citrullination in metastatic growth is evident in murine models where inhibition of citrullination substantially reduces liver metastatic burden. Additionally, citrullination of a key matrix component collagen type I promotes greater adhesion and decreased migration of CRC cells along with increased expression of characteristic epithelial markers, suggesting a role for citrullination in promoting mesenchymal-to-epithelial transition and liver metastasis. Overall, our study reveals the potential for PAD4-dependant citrullination to drive the progression of CRC liver metastasis
Instability of reconstruction of the low CMB multipoles
We discuss the problem of the bias of the Internal Linear Combination (ILC)
CMB map and show that it is closely related to the coefficient of
cross-correlation K(l) of the true CMB and the foreground for each multipole l.
We present analysis of the cross-correlation for the WMAP ILC quadrupole and
octupole from the first (ILC(I)) and the third (ILC(III)) year data releases
and show that these correlations are about -0.52-0.6. Analysing 10^4 Monte
Carlo simulations of the random Gaussian CMB signals, we show that the
distribution function for the corresponding coefficient of the
cross-correlation has a polynomial shape P(K,l)\propto(1-K^2)^(l-1). We show
that the most probable value of the cross-correlation coefficient of the ILC
and foreground quadrupole has two extrema at K ~= +/-0.58$. Thus, the ILC(III)
quadrupole represents the most probable value of the coefficient K. We analyze
the problem of debiasing of the ILC CMB and pointed out that reconstruction of
the bias seems to be very problematic due to statistical uncertainties. In
addition, instability of the debiasing illuminates itself for the quadrupole
and octupole components through the flip-effect, when the even (l+m) modes can
be reconstructed with significant error. This error manifests itself as
opposite, in respect to the true sign of even low multipole modes, and leads to
significant changes of the coefficient of cross-correlation with the
foreground. We show that the CMB realizations, whose the sign of quadrupole
(2,0) component is negative (and the same, as for all the foregrounds), the
corresponding probability to get the positive sign after implementation of the
ILC method is about 40%.Comment: 11 pages, 5 figure
Raman scattering in C_{60} and C_{48}N_{12} aza-fullerene: First-principles study
We carry out large scale {\sl ab initio} calculations of Raman scattering
activities and Raman-active frequencies (RAFs) in
aza-fullerene. The results are compared with those of .
Twenty-nine non-degenerate polarized and 29 doubly-degenerate unpolarized RAFs
are predicted for . The RAF of the strongest Raman
signal in the low- and high-frequency regions and the lowest and highest RAFs
for are almost the same as those of .
The study of reveals the importance of electron correlations and
the choice of basis sets in the {\sl ab initio} calculations. Our best
calculated results for with the B3LYP hybrid density functional
theory are in excellent agreement with experiment and demonstrate the desirable
efficiency and accuracy of this theory for obtaining quantitative information
on the vibrational properties of these molecules.Comment: submitted to Phys.Rev.
The elementary events underlying force generation in neuronal lamellipodia
We have used optical tweezers to identify the elementary events underlying force generation in neuronal lamellipodia. When an optically trapped bead seals on the lamellipodium membrane, Brownian fluctuations decrease revealing the underlying elementary events. The distribution of bead velocities has long tails with frequent large positive and negative values associated to forward and backward jumps occurring in 0.1–0.2 ms with varying amplitudes up to 20 nm. Jump frequency and amplitude are reduced when actin turnover is slowed down by the addition of 25 nM Jasplakinolide. When myosin II is inhibited by the addition of 20 μM Blebbistatin, jump frequency is reduced but to a lesser extent than by Jasplainolide. These jumps constitute the elementary events underlying force generation
Crop Updates 2000 - Weeds
This session covers thirty six papers from different authors:
INTRODUCTION, Vanessa Stewart Agriculture Western Australia
INTEGRATED WEED MANAGEMENT
Effect of seeding density, row spacing and Trifluralin on the competitive ability of Annual Ryegrass in a minimum tillage system, David Minkey, Abul Hashem, Glen Riethmuller and Martin Harries, Agriculture Western Australia
High wheat seeding rates coupled with narrow row spacing increases yield and suppresses grass, Peter Newman1 and Cameron Weeks2,1Agronomist, Elders Limited 2Mingenew/Irwin Group
Resistant ryegrass management in a wheat – lupin rotation, Abul Hashem, Harmohinder S. Dhammu, Aik Cheam, David Bowran and Terry Piper, Agriculture Western Australia
Integrated weed management – Will it work with my rotation? Alexandra Wallace, Agriculture Western Australia
Long term herbicide resistance trial – Mingenew, Peter Newman Elders, Cameron Weeks Mingenew-Irwin Group
Is two years enough? Bill Roy, Agricultural Consulting and Research Services
The fate of ryegrass seed when sheep graze chaff cart heaps, Keith L. Devenish1 and Lisa J. Leaver2 1 Agriculture Western Australia, 2Curtin University of Technology, Muresk Institute of Agriculture
Can blanket wiping and crop topping prevent seed set of resistant wild radish and mustard? StAbul Hashem, Harmohinder Dhammu, Vanessa Stewart, Brad Rayner and Mike Collins, Agriculture Western Australia
The value of green manuring in the integrated management of ryegrass, Marta Monjardino1,2, David Pannell2, Stephen Powles1 ,1Western Australia Herbicide Resistance Initiative, 2Agricultural and Resource Economics, University of Western Australia
Some ways of increasing wheat competitiveness against ryegrass,, Mike Collins Centre for Cropping Systems, Agriculture Western Australia
WEED BIOLOGY
Understanding and driving weed seed banks to very low levels, Sally Peltzer, Agriculture Western Australi
HERBICIDE RESISTANCE
Cross resistance of chlorsulfuron-resistant wild radish to imidazolinones, Abul Hashem, Harmohinder Dhammu and David Bowran, Agriculture Western Australia
Investigation of suspected triazine resistant ryegrass populations for cross-resistance and multiple resistance to herbicides, Michael Walsh, Charles Boyle and Stephen Powles, Western Australian Herbicide Resistance Initiative, University of Western Australia
Genetics and fitness of glyphosate resistant ryegrass, S. Powles1, P. Neve1, D. Lorraine-Colwill2, C. Preston2 ,1WAHRI, University of Western Australia 2 CRC Weed Management Systems, University of Adelaide
Managing herbicide resistance – the effect of local extinction of resistance genes, Art Diggle1, Paul B. Neve2, Stephen B. Powles2 ,1Agriculture Western Australia, 2WAHRI, Faculty of Agriculture, University of Western Australia
The double knock - the best strategy for conserving glyphosate susceptibility? Paul B. Neve1, Art Diggle2, Stephen B. Powles1,1WAHRI, Faculty of Agriculture, University of Western Australia, 2Agriculture Western Australia
Wild radish had evolved resistance to triazines, Abul Hashem, Harmohinder S. Dhammu, David Bowran and Aik Cheam, Agriculture Western Australia
Ryegrass resistance in Western Australia – where and how much? Rick Llewellyn and Stephen Powles, Western Australian Herbicide Resistance Initiative, Faculty of Agriculture, University of Western Australia
Wild radish herbicide resistance survey, Michael Walsh, Ryan Duane and Stephen Powles, Western Australian Herbicide Resistance Initiative, University of Western Australia
Knockdown resistance in the Western Australian wheatbelt – a proposed survey, Paul B. Neve1, Abul Hashem2, Stephen B. Powles1,1Western Australian Herbicide Resistance Initiative, University of Western Australia, 2Agriculture Western Australia
Diflufenican resistant wild radish, Aik Cheam, Siew Lee, David Bowran, David Nicholson and Abul Hashem, Agriculture Western Australi
Multiple resistance to triazines and diflufenican further complicates wild radish control, Aik Cheam, Siew Lee, David Bowran, David Nicholson and Abul Hashem, Agriculture Western Australia
HERBICIDE TOLERANCE
25. Herbicide tolerance of lupins, Terry Piper, Weed Science Group, Agriculture Western Australia
26. Tanjil lupins will tolerate metribuzin under the right conditions, Peter Newman, Agronomist Elders Limited and Cameron Weeks, Mingenew/Irwin Group
27. Herbicide damage does not mean lower yield in Lupins, Peter Carlton, Trials Coordinator, Elders Limited
28. Herbicide tolerance of new pea varieties, Dr Terry Piper, Agriculture Western Australia
29. Herbicide tolerance of (waterlogged) wheat, Dr Terry Piper, Agriculture Western Australia
30. Wheat tolerance trials – Mingenew 1999, Peter Newman1, Cameron Weeks2 and Stewart Smith3,1Elders, Mingenew, 2Mingenew-Irwin Group,3Agriculture Western Australia
ISSUES OF TRIFLURALIN USE
31. Trifluralin works better on ryegrass when no-tilling into thick wheat stubbles as granules, or mixed with limesand, Bill Crabtree, WANTFA Scientific Officer
32. Increasing trifluralin rate did not compensate for delaying incorporation, Bill Crabtree, WANTFA Scientific Officer
33. Poor emergence survey, 1999, Terry Piper, Weed Science Group, Agriculture Western Australia
HERBICIDES – ISSUES AND OPTIONS
34. AFFINITY 400DF – A new herbicide with a new mode of action (Group G) for Broadleaf Weed Control in Cereals, Gordon Cumming, Technical Officer, Crop Care Australasia
35 Herbicide screening for Marshmallow, David Minkey1 and David Cameron2,1Agriculture Western Australia, 2Elders Ltd, Merredin
36. The control of Capeweed in Clearfield Production System for Canola, Mike Jackson and Scott Paton, Cyanamid Agriculture Pty Ltd
37.Effect of herbicides Tordonä 75D and Lontrelä,used for eradication of Skeleton Weed, on production of Lupins I the following seasons, John R. Peirce and Brad J. Rayner, Agriculture Western Australia
INDUSTRY PROTECTION
38. Graingaurd – Opportunities for agribusiness to help protect the West Australian grains industry, Greg Shea, Executive Officer, GrainGuard Agriculture Western Australi
Less than 5 Netrin-1 molecules initiate attraction but 200 Sema3A molecules are necessary for repulsion
Guidance molecules, such as Sema3A or Netrin-1, induce growth cone (GC) repulsion or attraction. In order to determine the speed of action and efficiency of these guidance cues we developed an experimental procedure to deliver controlled amounts of these molecules. Lipid vesicles encapsulating 10-10 4 molecules of Sema3A or Netrin-1 were manipulated with high spatial and temporal resolution by optical tweezers and their photolysis triggered by laser pulses. Guidance molecules released from the vesicles diffused and reached the GC membrane in a few seconds. Following their arrival, GCs retracted or grew in 20-120 s. By determining the number of guidance molecules trapped inside vesicles and estimating the fraction of guidance molecules reaching the GC, we show that the arrival of less than 5 Netrin-1 molecules on the GC membrane is sufficient to induce growth. In contrast, the arrival of about 200 Sema3A molecules is necessary to induce filopodia repulsion
A Polarised Population of Dynamic Microtubules Mediates Homeostatic Length Control in Animal Cells
An analysis of cells grown on micro-patterned lines, and of cells during zebrafish development, identifies a population of microtubules that align along the long axis of cells to mediate homeostatic length control
A cyclic universe with colour fields
The topology of the universe is discussed in relation to the singularity
problem. We explore the possibility that the initial state of the universe
might have had a structure with 3-Klein bottle topology, which would lead to a
model of a nonsingular oscillating (cyclic) universe with a well-defined
boundary condition. The same topology is assumed to be intrinsic to the nature
of the hypothetical primitive constituents of matter (usually called preons)
giving rise to the observed variety of elementary particles. Some
phenomenological implications of this approach are also discussed.Comment: 21 pages, 9 figures; v.4: final versio
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