The enzymic degradation of lipids resulting from physical disruption of cucumber (Cucumis sativus) fruit

Homogenization of fresh tissue from cucumber fruits results in a loss of endogenous lipid catalysed by acyl hydrolase enzymes. Deacylation of lipids is not accompanied by accumulation of free fatty acids. The levels of both saturated (mainly palmitic) and polyunsaturated (linoleic and linolenic) fatty acids in the lipids are reduced. Losses of the major acyl lipid constituents of cucumber (triacylglycerols and phospholipids) are mainly responsible for the observed hydrolysis. Triacylglycerol acyl hydrolase (lipase), phospholipase D and polar lipid acyl hydrolase enzyme activities were demonstrated. It is suggested that hydrolytic attack on endogenous lipids is the initial event on disruption of cucumber tissue, in the formation of lipid degradation products, amongst which are the volatile carbonyl compounds responsible for the characteristic flavour of cucumber.     

Pulmonary phospholipied biosynthesis and the ability of the fetal rabbit lung to reduce cortisone to cortisol during the final ten days of gestation

Incubation of fetal lung tissue with 0.2 μM ¹⁴C-cortisone revealed a 12-fold increase in the rate of reduction of cortisone to cortisol between day 22 and day 30 of gestation in the rabbit. This increase correlated closely with the increase in the rate of incorporation of ¹⁴C-choline into total lung lipids during the same period. In light of these findings it would seem inadequate to attempt to relate the plasma cortisol concentration alone with the rate of lung maturation. In addition, one would need consider both the plasma concentration of cortisone and the activity of 11β-hydroxysteroid dehydrogenase (11β-HSD) in the lung.     

Antagonism of the ATP-gated P2X7 receptor: a potential therapeutic strategy for cancer

Purinergic Signalling - The P2X receptor 7 (P2X7R) is a plasma membrane receptor sensing extracellular ATP associated with a wide variety of cellular functions. It is most commonly expressed on...     

Differentiation of Isomeric Purine and Pyrimidine Mononucleotides by Fast Atom Bombardment Tandem Mass Spectrometry

Abstract

The use of positive ion fast atom bombardment mass-analysed ion kinetic energy (FAB/MIKE) spectroscopy to differentiate the 2′, 3′-and 5′-monophosphate isomers of adenosine, guanosine and cytidine is described.     

Developing a diagnostic model for estimating terrestrial vegetation gross primary productivity using the photosynthetic quantum yield and Earth Observation data

This article develops a new carbon exchange diagnostic model [i.e. Southampton CARbon Flux (SCARF) model] for estimating daily gross primary productivity (GPP). The model exploits the maximum quantum yields of two key photosynthetic pathways (i.e. C₃ and C₄) to estimate the conversion of absorbed photosynthetically active radiation into GPP. Furthermore, this is the first model to use only the fraction of photosynthetically active radiation absorbed by photosynthetic elements of the canopy (i.e. FAPAR_ps) rather than total canopy, to predict GPP. The GPP predicted by the SCARF model was comparable to in situ GPP measurements (R² > 0.7) in most of the evaluated biomes. Overall, the SCARF model predicted high GPP in regions dominated by forests and croplands, and low GPP in shrublands and dry‐grasslands across USA and Europe. The spatial distribution of GPP from the SCARF model over Europe and conterminous USA was comparable to those from the MOD17 GPP product except in regions dominated by croplands. The SCARF model GPP predictions were positively correlated (R² > 0.5) to climatic and biophysical input variables indicating its sensitivity to factors controlling vegetation productivity. The new model has three advantages, first, it prescribes only two quantum yield terms rather than species specific light use efficiency terms; second, it uses only the fraction of PAR absorbed by photosynthetic elements of the canopy (FAPAR_ps) hence capturing the actual PAR used in photosynthesis; and third, it does not need a detailed land cover map that is a major source of uncertainty in most remote sensing based GPP models. The Sentinel satellites planned for launch in 2014 by the European Space Agency have adequate spectral channels to derive FAPAR_ps at relatively high spatial resolution (20 m). This provides a unique opportunity to produce global GPP operationally using the Southampton CARbon Flux (SCARF) model at high spatial resolution.