Step-by-step acquisition of the gibberellin-DELLA growth-regulatory mechanism during land-plant evolution.

Angiosperms (flowering plants) evolved relatively recently and are substantially diverged from early land plants (bryophytes, lycophytes, and others [1]). The phytohormone gibberellin (GA) adaptively regulates angiosperm growth via the GA-DELLA signaling mechanism [2-7]. GA binds to GA receptors (GID1s), thus stimulating interactions between GID1s and the growth-repressing DELLAs [8-12]. Subsequent 26S proteasome-mediated destruction of the DELLAs promotes growth [13-17]. Here we outline the evolution of the GA-DELLA mechanism. We show that the interaction between GID1 and DELLA components from Selaginella kraussiana (a lycophyte) is GA stimulated. In contrast, GID1-like (GLP1) and DELLA components from Physcomitrella patens (a bryophyte) do not interact, suggesting that GA-stimulated GID1-DELLA interactions arose in the land-plant lineage after the bryophyte divergence ( approximately 430 million years ago [1]). We further show that a DELLA-deficient P. patens mutant strain lacks the derepressed growth characteristic of DELLA-deficient angiosperms, and that both S. kraussiana and P. patens lack detectable growth responses to GA. These observations indicate that early land-plant DELLAs do not repress growth in situ. However, S. kraussiana and P. patens DELLAs function as growth-repressors when expressed in the angiosperm Arabidopsis thaliana. We conclude that the GA-DELLA growth-regulatory mechanism arose during land-plant evolution and via independent stepwise recruitment of GA-stimulated GID1-DELLA interaction and DELLA growth-repression functions

The effect of carboxymethyl cellulose (CMC) addition at dosage stage on the foam attributes of traditional method English Sparkling Wine

Carboxymethyl cellulose (CMC) is a novel winemaking product used in winemaking to prevent potassium bitartrate or potassium hydrogen tartrate deposits from forming. These deposits are particularly detrimental when occurring in bottles of traditional method sparkling wine ahead of disgorging or in the finished product as they can cause gushing of the wine when bottles are opened. Despite CMC being used by several sparkling winemaking producer, its effect on the behaviour of foam, a key indicator of sparkling wine quality, has not been systematically tested. In this work we assessed the effect of CMC (StabivinTM) addition to English Sparkling Wine (ESW) at the dosage stage at levels ranging from 0.25 mg/L to 1 mg/L. Foamability and foam stability was assessed using two methods; an adapted Mosalux method and a novel image analysis method, designed to simulate more accurately ‘real world’ serving conditions when assessing foam behaviour. Parameters as foam height, foam stability, collar formation and stability, foam collapsing time, changes in viscosity were all measured. Despite different rates of CMC addition, it showed little effects on some of the foam parameters observed when compared to the control, overall detrimental effect of CMC on foam attributes was observed. These results suggest CMC can be added at the dosage stage without compromising ESW foam quality attributes

Starch synthase 4 is essential for coordination of starch granule formation with chloroplast division during Arabidopsis leaf expansion

Arabidopsis thaliana mutants lacking the SS4 isoform of starch synthase have strongly reduced numbers of starch granules per chloroplast, suggesting that SS4 is necessary for the normal generation of starch granules. To establish whether it plays a direct role in this process, we investigated the circumstances in which granules are formed in ss4 mutants. Starch granule numbers and distribution and the accumulation of starch synthase substrates and products were investigated during ss4 leaf development, and in ss4 mutants carrying mutations or transgenes that affect starch turnover or chloroplast volume. We found that immature ss4 leaves have no starch granules, but accumulate high concentrations of the starch synthase substrate ADPglucose. Granule numbers are partially restored by elevating the capacity for glucan synthesis (via expression of bacterial glycogen synthase) or by increasing the volumes of individual chloroplasts (via introduction of arc mutations). However, these granules are abnormal in distribution, size and shape. SS4 is an essential component of a mechanism that coordinates granule formation with chloroplast division during leaf expansion and determines the abundance and the flattened, discoid shape of leaf starch granules

CFD Based Study of Unconventional Aeroengine Exhaust Systems

The effect of upstream duct curvature on the exhaust plume of a jet engine is cur- rently undocumented. Here, three different upstream curvatures are simulated using CFD to investigate the effect of upstream duct curvature on the over-expanded exhaust plume emanating from a rectangular nozzle of aspect ratio 5.8:1 at a nozzle pressure ratio of 2.5 and Reynolds number of 7.61 × 105. Due to the lack of available experimental data for curved ducts connected to high speed jets, the initial work was to validate the methodol- ogy for separate S-bend and rectangular nozzle high speed jet cases. These showed that RANS methods were poor for predicting secondary flows in the S-bend and for predicting mixing and potential core length in the rectangular jet. However, LES did show signifi- cant improvements for the rectangular jet and correctly predicts the shear layer mixing. Calculations were carried out using an unstructured, median-dual CFD solver with pre- dominantly hexahedral elements containing approximately 65.5−67.5 million nodes. For the combined S-bend and nozzle cases it was seen that increasing upstream duct curvature re- duces the potential core length and increases losses in the upstream duct. Transverse total pressure gradients were also observed at the nozzle exit plane in both k-ǫ and WALE LES turbulence models, however to a significantly smaller degree in the latter. The upstream duct curvature was also seen to have an impact on the shock cell development, altering both number and location