Cyclooxygenase and lipoxygenase-like activity in Drosophila melanogaster

To determine the possible activity of cyclooxygenase and lipoxygenase like enzymes in Drosophila melanogaster, we have investigated whether fly homogenates can biosynthesize prostaglandins and HETEs. Incubation of fly extracts with AA yields a mixture of 15- 12- 9- and 8-HETE as detected by selected ion monitoring GC-MS. Also the combination of HPLC-RIA using a PGE antibody shows the presence of endogenous PGE2 immunoreactivity in the extracts (405 pg/g in males and 165 pg/g in females). We have also detected the presence of lipoxygenase like immunoreactivity in the reproductive male system by using immunocytochemical techniques in whole body sections of the fly as well as reactivity in the digestive system of both males and females. Finally, we have not been able to detect endogenous AA in the fly by GC-MS methods. However, estimates by GC-MS of the total body fatty acids indicate substantial amounts of potential AA precursors.     

Pyridoxal thiosemicarbazonate monohydrate of dimethylthallium(III): X-ray structure and spectroscopic properties

The title compoud, [TlMe₂(HL)(H₂O)] (HL = monoanion of pyridoxal thiosemicarbazone), crystallizers in the triclinic space group , No. 2). The HL⁻anion coordinates to the thallium atom, in an unusual mode through the S atom (Tl-S = 2.832(1) Å), and also forms a weak bond with the metal atom of a neighbouring molecule to make an asymmetric bridge (Tl′…S = 3.190(1) Å). The acidic proton retained in the thiosemicarbazonato anion is located on the oxygen of the phenolic hydroxyl group. The water molecule is only 2.630(4) Å from the metal, suggesting a rather strong bond that contrasts with the long distance between the thallium and the phenolic oxygen (Tl…O(1)′ = 3.124(4) Å). If both strong and weak intermolecular interactions are taken in account, the metal has distorted octahedral coordination with the methyl groups in apical positions. The solid state IR spectrum and ¹H, ¹³C and ²⁰⁵Tl NMR spectra in DMSO solution are also discussed.     

Leaf growth rate and nitrogen content determine respiratory costs during leaf expansion in grapevines

Respiration processes are well recognized as fundamental for the plant carbon balance, but little attention has been paid to the relationships among respiration rates, environment and genetic variability. This can be of particular interest to understand the differences in net carbon balances in crops as grapevines. Night respiration (R_n) and its associated growth (R_g) and maintenance (R_m) components were evaluated during leaf expansion in two grapevine cultivars (Tempranillo cv. and Garnacha cv.) that differ in their plant growth pattern and carbon balance. Simultaneously, leaf traits as leaf mass area, nitrogen (N) and carbon (C) content were evaluated in order to relate to the respiratory processes and the leaf growth. The results showed the differences in respiration rates associated with the leaf expansion pattern. Tempranillo developed leaves with higher leaf area and lower dry weight per leaf unit than Garnacha. Although differences between cultivars were observed in terms of growth costs in expanding leaves, the maintenance costs were similar for both cultivars. Also, a significant linear regression was found between respiration rates and N content in expanding and mature leaves. The results indicate that differences in structure and nitrogen content of expanding leaves may lead to respiratory differences between cultivars. These results also demonstrate the importance of respiratory cost components in carbon balance calculations in grapevines.