Fructan biosynthesis in Lolium perenne : tissue, cultivar and temperature effects on gene expression and protein accumulation profiles : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Palmerston North, New Zealand

Cultivars of Lolium perenne with high concentrations of water soluble carbohydrates (WSCs) offer opportunities to mitigate greenhouse gas emissions (nitrous oxides) from grazed pastures and improve meat and milk production in livestock. Our previous studies demonstrated that fructan accumulation in the blades of high W SC grasses involves a strong gene x environment interaction. To identify the temperature effects on the expression of high sugar trait in the high sugar cultivars. we conducted a pot trial in climate chambers with temperature regimes set at10/10, 20/10 and 20/20°C (day/night), respectively. Water soluble carbohydrate concentrations, the expression of the key genes and proteins: l-SST (sucrose: sucrose l-fructosyltransferase), l-FFT (fructan: fructan l-fruclosyltransferase), 6G-FFT (fructan: fructan 6G-fructosyltransferase) and l-FEH l-fructan exohydrolases) involved in the fructan biosynthetic pathway of L. perenne were compared in blades and sheaths of three selected high sugar cultivars (P, A and H) and a common cultivar (F) grown under the three temperature regimes. We found that amongst the selected 3 high sugar cultivars, high molecular weight (HMW) WSC content was significantly higher in P and A cultivars, regardless of the temperature regimes. As expected, sheaths contained significantly higher concentrations of HMW WSCs (fructans) compared to leaf blades. The highest WSC contents in both leaf and sheath tissues accumulated at 10/10°C while the lowest accumulated at 20/20°C. Gene expression profiles demonstrated that all four genes studied were more significantly expressed in sheaths compared to blades, and the expression levels were highly correlated with fructan accumulation in this tissue. Low temperature resulted in significant up-regulation of l-SST in sheaths, but not in blades. l-FFT was highly expressed in blades of A and P cultivars. Unexpectedly. 6G-FFT was expressed more significantly in the control F cultivar. but not in the high sugar cultivar P. Protein expression profiles showed that l -SST protein accumulated to high levels in sheaths, whereas protein levels of l-FFT and l-FEH were higher in blades. l-SST protein levels in both blades and sheaths generally increased in plants grown at low temperatures, whereas l-FFT protein was not affected by low temperatures in blades and sheaths, furthermore, in both tissues there was no consistent effect observed between the different cultivars and temperature regimes on l-FEH protein levels

Generating Hermite polynomial excited squeezed states by means of conditional measurements on a beam splitter

A scheme for conditional generating a Hermite polynomial excited squeezed vacuum states (HESVS) is proposed. Injecting a two-mode squeezed vacuum state (TMSVS) into a beam splitter (BS) and counting the photons in one of the output channels, the conditional state in the other output channel is just a HESVS. To exhibit a number of nonclassical effects and non-Guassianity, we mainly investigate the photon number distribution, sub-Poissonian distribution, quadrature component distribution, and quasi-probability distribution of the HPESVS. We find that its nonclassicality closely relates to the control parameter of the BS, the squeezed parameter of the TMSVS, and the photon number of conditional measurement. These further demonstrate that performing the conditional measurement on a BS is an effective approach to generate non-Guassian state.Comment: 8 pages, 8 figures. arXiv admin note: text overlap with arXiv:quant-ph/9703039 by other author

Estimating decay rate of X±(5568)→Bsπ±X^{\pm}(5568)\to B_s\pi^{\pm} while assuming them to be molecular states

Discovery of $X(5568)$ brings up a tremendous interest because it is very special, i.e. made of four different flavors. The D0 collaboration claimed that they observed this resonance through portal $X(5568)\to B_s\pi$, but unfortunately, later the LHCb, CMS, CDF and ATLAS collaborations' reports indicate that no such state was found. Almost on the Eve of 2017, the D0 collaboration reconfirmed existence of $X(5568)$ via the semileptonic decay of $B_s$. To further reveal the discrepancy, supposing $X(5568)$ as a molecular state, we calculate the decay rate of $X(5568)\rightarrow B_s\pi^+$ in an extended light front model. Numerically, the theoretically predicted decay width of $\Gamma(X(5568)\rightarrow B_s\pi^+)$ is $20.28$ MeV which is consistent with the result of the D0 collaboration ($\Gamma=18.6^{+7.9}_{-6.1}(stat)^{+3.5}_{-3.8}(syst)$ MeV). Since the resonance is narrow, signals might be drowned in a messy background. In analog, two open-charm molecular states $DK$ and $BD$ named as $X_a$ and $X_b$, could be in the same situation. The rates of $X_a\to D_s\pi^0$ and $X_b\to B_c\pi^0$ are estimated as about 30 MeV and 20 MeV respectively. We suggest the experimental collaborations round the world to search for these two modes and accurate measurements may provide us with valuable information.Comment: 13 pages and 4 figures, accepted by EPJ

How can X±(5568)X^{\pm}(5568) escape detection?

Multi-quark states were predicted by Gell-Mann when the quark model was first formulated. Recently, numerous exotic states that are considered to be multi-quark states have been experimentally confirmed (four-quark mesons and five-quark baryons). Theoretical research indicates that the four-quark state might comprise molecular and/or tetraquark structures. We consider that the meson containing four different flavors $su\bar b\bar d$ should exist and decay via the $X(5568)\to B_s\pi$ channel. However, except for the D0 collaboration, all other experimental collaborations have reported negative observations for $X(5568)$ in this golden portal. This contradiction has stimulated the interest of both theorists and experimentalists. To address this discrepancy, we propose that the assumed $X(5568)$ is a mixture of a molecular state and tetraquark, which contributes destructively to $X(5568)\to B_s\pi$. The cancellation may be accidental and it should be incomplete. In this scenario, there should be two physical states with the same flavor ingredients, with spectra of $5344\pm307$ and $6318\pm315$. $X(5568)$ lies in the error range of the first state. We predict the width of the second state (designated as $S_2$) as $\Gamma(X_{S_2}\to B_s\pi)=224\pm97$ MeV. We strongly suggest searching for it in future experiments.Comment: pages 4. Accepted by phys. lett.

Study on decays of Zc(4020)Z_c(4020) and Zc(3900)Z_c(3900) into hc+πh_c+\pi

At the invariant mass spectrum of $h_c\pi^\pm$ a new resonance $Z_c(4020)$ has been observed, however the previously confirmed $Z_c(3900)$ does not show up at this channel. In this paper we assume that $Z_c(3900)$ and $Z_c(4020)$ are molecular states of $D\bar D^*(D^{*} \bar D)$ and $D^*\bar D^*$ respectively, then we calculate the transition rates of $Z_c(3900)\to h_c+\pi$ and $Z_c(4020)\to h_c+\pi$ in the light front model. Our results show that the partial width of $Z_c(3900)\to h_c+\pi$ is only three times smaller than that of $Z_c(4020)\to h_c+\pi$. $Z_c(4020)$ seems to be a molecular state, so if $Z_c(3900)$ is also a molecular state it should be observed in the portal $e^+e^-\to h_c\pi^\pm$ as long as the database is sufficiently large, by contrary if the future more precise measurements still cannot find $Z_c(3900)$ at $h_c\pi^\pm$ channel, the molecular assignment to $Z_c(3900)$ should be ruled out.Comment: 15 pages, 4 figures, will be published in EPJ