Uncarinic acids: phospholipase Cgamma1 inhibitors from hooks of Uncaria rhynchophylla.

Bioactivity-guided fractionation of the CHCl3 extract from hooks of Uncaria rhynchophylla led to the isolation of two triterpene esters, namely uncarinic acids A (1) and B (2). Their structures were established by spectroscopic and chemical methods. These compounds inhibited phospholipase Cgamma1 with IC50 values of 35.66 and 44.55 microM, respectively.     

Phosphorylation of Ser 21 in Fyn regulates its kinase activity,focal adhesion targeting,and is required for cell migration

The tyrosine kinase Fyn is a member of the Src family kinases which are important in many integrin‐mediated cellular processes including cell adhesion and migration. Fyn has multiple phosphorylation sites which can affect its kinase activity. Among these phosphorylation sites, the serine 21 (S21) residue of Fyn is a protein kinase A (PKA) recognition site within an RxxS motif of the amino terminal SH4 domain of Fyn. In addition, S21 is critical for Fyn kinase‐linked cellular signaling. Mutation of S21A blocks PKA phosphorylation of Fyn and alters its tyrosine kinase activity. Expression of Fyn S21A in cells lacking Src family kinases (SYF cell) led to decreased tyrosine phosphorylation of focal adhesion kinase resulting in reduced focal adhesion targeting, which slowed lamellipodia dynamics and thus cell migration. These changes in cell motility were reflected by the fact that cells expressing Fyn S21A were severely deficient in their ability to assemble and disassemble focal adhesions. Taken together, our findings indicate that phosphorylation of S21 within the pPKA recognition site (RxxS motif) of Fyn regulates its tyrosine kinase activity and controls focal adhesion targeting, and that this residue of Fyn is critical for transduction of signals arising from cell‐extracellular matrix interactions. J. Cell. Physiol. 226: 236–247, 2010. © 2010 Wiley‐Liss, Inc.     

Accumulation and localisation of sodium ions within the shoots of rice (Oryza sativa) varieties differing in salinity resistance

Oryza sativa L. (rice) is a salt-sensitive crop species which is relatively ineffective in controlling the influx of sodium and chloride ions to the shoot. Nonetheless, there is considerable varietal and individual variability in salinity resistance, much of which must derive, therefore, from differences in the fates and subsequent effects of saline ions after they have entered the plant. The destination of sodium ions within the plant has been investigated, in saline conditions, by examining the time-course of sodium ion concentrations in different leaves of four varieties and breeding lines of rice of differing salinity resistance. Radionuclide tracers were employed to study short term effects and the degree of retranslocation of these sodium ions. Sodium was not distributed uniformly but accumulated in the older leaves before the younger ones. At least some leaves were maintained at sub-lethal salt concentrations in at least the more salt resistant varieties. Radionuclide tracer studies showed that the discontinuous distribution of sodium (from leaf to leaf) is constitutive, and cannot be explained by time of exposure or differential leaf growth rates, and that significant quantities of sodium were not subsequently retranslocated, either within the plant or to the root medium.     

Recent advances in the discovery and combinatorial biosynthesis of microbial 14-membered macrolides and macrolactones

Journal of Industrial Microbiology & Biotechnology - Macrolides, especially 14-membered macrolides, are a valuable group of antibiotics that originate from various microorganisms. In addition...