1,481 research outputs found
Fruit softening: evidence for rhamnogalacturonan lyase action in vivo in ripe fruit cell walls
Background and aims The softening of ripening fruit involves partial depolymerisation of cell-wall pectin by three types of reaction: enzymic hydrolysis, enzymic elimination (lyase-catalysed) and non-enzymic oxidative scission. Two known lyase activities are pectate lyase and rhamnogalacturonan lyase (RGL), potentially causing mid-chain cleavage of homogalacturonan and rhamnogalacturonan-I (RG-I) domains of pectin respectively. However, the important biological question of whether RGL exhibits action in vivo had not been tested.Methods We developed a method for specifically and sensitively detecting in-vivo RGL products, based on Driselase digestion of cell walls and detection of a characteristic unsaturated ‘fingerprint’ product (tetrasaccharide) of RGL action. Key Results In model experiments, potato RG-I that had been partially cleaved in vitro by commercial RGL was digested by Driselase, releasing an unsaturated tetrasaccharide (‘UA-Rha-GalA-Rha’), taken as diagnostic of RGL action. This highly acidic fingerprint compound was separated from monosaccharides (galacturonate, galactose, rhamnose etc.) by electrophoresis at pH 2, then separated from UA–GalA (the fingerprint of pectate lyase action) by thin-layer chromatography (TLC). The ‘UA-Rha-GalA-Rha’ was confirmed as 4-deoxy--L-threo-hex-4-enopyranuronosyl-(12)-L-rhamnosyl-(14)-D-galacturonosyl-(12)-L-rhamnose by mass spectrometry and acid hydrolysis. Driselase digestion of cell walls from diverse ripe fruits [date, sea buckthorn, cranberry, yew (arils), mango, plum, blackberry, apple, pear and strawberry] yielded the same fingerprint compound, demonstrating that RGL had been acting in vivo in these fruits prior to harvest. The ‘fingerprint’ : (galacturonate + rhamnose) ratio in digests from ripe dates was approximately 1:72 (mol/mol), indicating that ~1.4% of the backbone RhaGalA bonds in endogenous RG-I had been cleaved by in-vivo RGL action. Conclusions The results provide the first demonstration that RGL, previously known from studies of fruit gene expression, proteomic studies and in-vitro enzyme activity, exhibits enzyme action in the walls of soft fruits and may thus be proposed to contribute to fruit softening. <br/
Montbresides A–D:Antibacterial p-coumaroyl esters of a new sucrose-based tetrasaccharide from Crocosmia × crocosmiiflora (montbretia) flowers
Fruit softening:Evidence for pectate lyase action in vivo in date (Phoenix dactylifera) and rosaceous fruit cell walls
Unhatched eggs represent the invisible fraction in two wild bird populations
Prenatal mortality is typically overlooked in population studies, which biases evolutionary inference by confounding selection and inheritance. Birds represent an opportunity to include this ‘invisible fraction’ if each egg contains a zygote, but whether hatching failure is caused by fertilization failure versus prenatal mortality is largely unknown. We quantified fertilization failure rates in two bird species that are popular systems for studying evolutionary dynamics and found that overwhelming majorities (99.9%) of laid eggs were fertilized. These systems thus present opportunities to eliminate the invisible fraction from life-history data
Solid State Proton Spin Relaxation and Methyl and \u3ci\u3et\u3c/i\u3e-Butyl Reorientation
We have measured the temperature T and Larmor frequency ω/2π dependence of the proton spin‐lattice relaxation rate R in solid 1‐hydroxy‐2,4,6‐tri‐butylbenzene. The data is interpreted in terms of the rotational motion of the t‐butyl groups and their constituent methyl groups. Our data is much more extensive than a previous report [J. Yamauchi and C. A. McDowell, J. Chem. Phys. 75, 1051 (1981)] resulting in a revised dynamical model and considerably larger rotational barriers. Interesting thermal history effects are discussed
A Role for Thymic Stromal Lymphopoietin in CD4+ T Cell Development
Thymic stromal lymphopoietin (TSLP) signals via a receptor comprising the interleukin (IL)-7 receptor α chain and a distinctive subunit, TSLP receptor (TSLPR), which is most related to the common cytokine receptor γ chain, γc. We have generated TSLPR knockout (KO) mice and found that although these mice had normal lymphocyte numbers, γc/TSLPR double KO mice had a greater lymphoid defect than γc KO mice. This indicates that TSLP contributes to lymphoid development and accounts for some of the residual lymphoid development in γc KO mice and presumably in patients with X-linked severe combined immunodeficiency. Injection of TSLP into γc KO mice induced the expansion of T and B cells. Moreover, sublethally irradiated TSLPR KO mice showed weaker recovery of lymphocyte populations than wild-type (WT) littermates, even when neutralizing anti–IL-7 antibodies were injected. Interestingly, TSLP preferentially stimulated the proliferation and survival of CD4+ single positive thymocytes and peripheral T cells in vitro. Additionally, CD4+ T cells from TSLPR KO mice expanded less efficiently than WT CD4+ T cells in irradiated hosts, and TSLP preferentially expanded CD4+ T cells both in vitro and in vivo. Thus, as compared with other known cytokines, TSLP is distinctive in exhibiting a lineage preference for the expansion and survival of CD4+ T cells
Financial development and economic growth in an oil-rich economy: The case of Saudi Arabia
© 2014 Elsevier B.V.We investigate the effect of financial development on economic growth in the context of Saudi Arabia, an oil-rich economy. In doing so, we distinguish between the effects of financial development on the oil and non-oil sectors of the economy. Using the Autoregressive Distributed Lag (ARDL) Bounds test technique, we find that financial development has a positive impact on the growth of the non-oil sector. In contrast, its impact on the oil-sector growth and total GDP growth is either negative or insignificant. This suggests that the relationship between financial development and growth may be fundamentally different in resource-dominated economies
Biofilter aquaponic system for nutrients removal from fresh market wastewater
Aquaponics is a significant wastewater treatment system which refers to the combination of conventional aquaculture (raising aquatic organism) with hydroponics (cultivating plants in water) in a symbiotic environment. This system has a high ability in removing nutrients compared to conventional methods because it is a natural and environmentally friendly system (aquaponics). The current chapter aimed to review the possible application of aquaponics system to treat fresh market wastewater with the intention to highlight the mechanism of phytoremediation occurs in aquaponic system. The literature revealed that aquaponic system was able to remove nutrients in terms of nitrogen and phosphorus
Astro2020 Science White Paper: Triggered High-Priority Observations of Dynamic Solar System Phenomena
Unexpected dynamic phenomena have surprised solar system observers in the
past and have led to important discoveries about solar system workings.
Observations at the initial stages of these events provide crucial information
on the physical processes at work. We advocate for long-term/permanent programs
on ground-based and space-based telescopes of all sizes - including Extremely
Large Telescopes (ELTs) - to conduct observations of high-priority dynamic
phenomena, based on a predefined set of triggering conditions. These programs
will ensure that the best initial dataset of the triggering event are taken;
separate additional observing programs will be required to study the temporal
evolution of these phenomena. While not a comprehensive list, the following are
notional examples of phenomena that are rare, that cannot be anticipated, and
that provide high-impact advances to our understandings of planetary processes.
Examples include: new cryovolcanic eruptions or plumes on ocean worlds; impacts
on Jupiter, Saturn, Uranus, or Neptune; extreme eruptions on Io; convective
superstorms on Saturn, Uranus, or Neptune; collisions within the asteroid belt
or other small-body populations; discovery of an interstellar object passing
through our solar system (e.g. 'Oumuamua); and responses of planetary
atmospheres to major solar flares or coronal mass ejections.Comment: Astro2020 white pape
Impact of air pollution on educational attainment for respiratory health treated students: A cross sectional data linkage study
Introduction: There is some evidence that exam results are worse when students are acutely exposed to air pollution. Studies investigating the association between air pollution and academic attainment have been constrained by small sample sizes. Methods: Cross sectional educational attainment data (2009–2015) from students aged 15–16 years in Cardiff, Wales were linked to primary health care data, modelled air pollution and measured pollen data, and analysed using multilevel linear regression models. Annual cohort, school and individual level confounders were adjusted for in single and multi-pollutant/pollen models. We stratified by treatment of asthma and/or Seasonal Allergic Rhinitis (SAR). Results: A unit (10μg/m3) increase of short-term exposure to NO2 was associated with 0.044 (95% CI: −0.079, −0.008) reduction of standardised Capped Point Score (CPS) after adjusting for individual and household risk factors for 18,241 students. This association remained statistically significant after controlling for other pollutants and pollen. There was no association of PM2.5, O3, or Pollen with standardised CPS remaining after adjustment. We found no evidence that treatment for asthma or SAR modified the observed NO2 effect on educational attainment. Conclusion: Our study showed that short-term exposure to traffic-related air pollution, specifically NO2, was associated with detrimental educational attainment for students aged 15–16. Longitudinal investigations in different settings are required to confirm this possible impact and further work may uncover the long-term economic implications, and degree to which impacts are cumulative and permanent
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