Evolved polygenic herbicide resistance in Lolium rigidum by low-dose herbicide selection within standing genetic variation

The interaction between environment and genetic traits under selection is the basis of evolution. In this study, we have investigated the genetic basis of herbicide resistance in a highly characterized initially herbicide-susceptible Lolium rigidum population recurrently selected with low (below recommended label) doses of the herbicide diclofop-methyl. We report the variability in herbicide resistance levels observed in F1 families and the segregation of resistance observed in F2 and back-cross (BC) families. The selected herbicide resistance phenotypic trait(s) appear to be under complex polygenic control. The estimation of the effective minimum number of genes (NE), depending on the herbicide dose used, reveals at least three resistance genes had been enriched. A joint scaling test indicates that an additive-dominance model best explains gene interactions in parental, F1, F2 and BC families. The Mendelian study of six F2 and two BC segregating families confirmed involvement of more than one resistance gene. Cross-pollinated L. rigidum under selection at low herbicide dose can rapidly evolve polygenic broad-spectrum herbicide resistance by quantitative accumulation of additive genes of small effect. This can be minimized by using herbicides at the recommended dose which causes high mortality acting outside the normal range of phenotypic variation for herbicide susceptibility

Dynamical Models in Quantitative Genetics

In this paper the author investigates models in quantitative genetics and shows that under quite reasonable assumptions the dynamics can display rather counter-intuitive behavior. This research was conducted as part of the Dynamics of Macrosystems Feasibility Study in the System and Decision Sciences Program

Surface residues dynamically organize water bridges to enhance electron transfer between proteins

Cellular energy production depends on electron transfer (ET) between proteins. In this theoretical study, we investigate the impact of structural and conformational variations on the electronic coupling between the redox proteins methylamine dehydrogenase and amicyanin from Paracoccus denitrificans. We used molecular dynamics simulations to generate configurations over a duration of 40ns (sampled at 100fs intervals) in conjunction with an ET pathway analysis to estimate the ET coupling strength of each configuration. In the wild type complex, we find that the most frequently occurring molecular configurations afford superior electronic coupling due to the consistent presence of a water molecule hydrogen-bonded between the donor and acceptor sites. We attribute the persistence of this water bridge to a "molecular breakwater" composed of several hydrophobic residues surrounding the acceptor site. The breakwater supports the function of nearby solvent-organizing residues by limiting the exchange of water molecules between the sterically constrained ET region and the more turbulent surrounding bulk. When the breakwater is affected by a mutation, bulk solvent molecules disrupt the water bridge, resulting in reduced electronic coupling that is consistent with recent experimental findings. Our analysis suggests that, in addition to enabling the association and docking of the proteins, surface residues stabilize and control interprotein solvent dynamics in a concerted way

Toxicological studies on Helicoverpa armigera in pigeonpea growing in Vidarbha region of Maharashtra, India

Insecticide resistance level in pigeonpea pod borer, Helicoverpa armigera (Hubner) to technical grade insecticides collected from major pigeonpea growing districts of Vidarbha viz., Akola, Amravati, Buldhana, Yavatmal and Washim was worked out. LDP indicated LD50 of Cypermethrin in the range of 1.402 to 9.209 ppm with maximum in Yavatmal (9.209 ppm); LD90 within range of 6.021 to 18.427 ppm. LD50 of Quinalphos in the range of 1.303 to 4.789 ppm with maximum in Yavatmal (4.789 ppm); LD90 within range of 3.150 to 14.194 ppm.LD50 of Methomyl in the range of 1.297 to 3.792 ppm with maximum in Yavatmal (3.792 ppm); LD90 within range of 4.993 to 16.737 ppm.LD50 of Indoxacarb in the range of 0.521 to 2.709 ppm with maximum in Yavatmal (2.709 ppm); LD90 within range of 2.819 to 20.947 ppm.LD50 of Spinosad in the range of 0.713 to 2.408 ppm with maximum in Buldhana (2.408 ppm); LD90 within range of 6.413 to 18.349 ppm. The resistance level is visibly high in cypermethrin, moderate to indoxacarb, quinalphos, spinosad and low to methomyl; Yavatmal and Washim strains expressed higher resistance level to cypermethrin, quinalphos and methomyl, whereas Yavatmal and Buldhana strains expressed higher resistance level to indoxacarb and spinosad. The investigation will help to track resistence level in Helicoverpa armigera to different groups of insecticides

The Solar Neutrino Problem in the Light of a Violation of the Equivalence Principle

We have found that long-wavelength neutrino oscillations induced by a tiny breakdown of the weak equivalence principle of general relativity can provide a viable solution to the solar neutrino problem.Comment: 3 pages, 1 eps figure, Talk given by R. Zukanovich Funchal at the VIth International Workshop on ``Topics in Astroparticle and Underground Physics'' (TAUP99), Sep. 6-10, 1999, College de France, Paris - Franc

Potential of Pineapple Madu Shell (Ananas Comosus (L.) Merr.) as Anti-Browning Agent in Apples Manalagi (Malus Sylvestris Mill)

The purpose of this study was to determine the effect of water extract of pineapple shell in the process of browning apple manalagi (Malus sylvestris Mill). The research was conducted from October to November 2016 in the Laboratory of Plant Physiology Department of Biology, Faculty of Mathematics and Natural Sciences, University of Lampung. As variables were browning index, total soluble carbohydrate content, dehydrogenase enzyme activity, and reducing sugar levels, while the parameter is the mean of all variables. The experiment was conducted in completely randomizes design. The main factor was the water extract of the pineapple shell with 5 concentration levels: 0% v / v, 25% v / v, 50% v / v, 75% v / v, 100% v / v. Levene test, analysis of variance and LSD test was carried out at 5% significance level. The results showed that the water extract pineapple shell was significantly lower the browning index of apples manalagi, and the relationship between the concentration and browning index is quadratic (y = 9E-05x2 - 0.013x + 1.018 R² = 0665). Extract of pineapple shell did not significantly affect total soluble carbohydrate content of apples manalagi but a downward trend in total soluble carbohydrate content with increasing concentrations of the extract (y = -0.049x + 29.66 R² = 0.923). The relationship between the concentration of water extract pineapple shell with dehydrogenase enzyme activity was negative linear (y = -0.082x + 12.04 R² = 0.969). Reducing sugar levels increase at the concentration of 50% v/v,75% v/v, and 100% v/v. The final conclusion was that the water extract of pineapple shell was potential as anti-browning agent for apples manalagi because it was able to reduce browning index 51.89%, and influence other physiological processes

Violation of Equivalence Principle and Solar Neutrinos

We have updated the analysis for the solution to the solar neutrino problem by the long-wavelength neutrino oscillations induced by a tiny breakdown of the weak equivalence principle of general relativity, and obtained a very good fit to all the solar neutrino data.Comment: 3 pages, 5 figures, uses espcrc2.sty, Talk presented by H. Nunokawa at Europhysics Neutrino Oscillation Workshop (NOW2000), Otranto, Italy, September 9-16, 200