Metabolic cross-talk

Hampel, D., Mosandl, A., and Wust, M., Biosynthesis of mono- and sesquiterpenes in carrot roots and leaves (Daucus carota L.) metabolic cross talk of cytosolic mevalonate and plastidial methylerythritol phosphate pathways, Phytochemistry 66, 305, 2005. 

Figure 3.8 Metabolic cross-talk between glucosinolate and cyanogenic glucoside biosynthesis in transgenic Arabidopsis plants (according to Kristensen et a ., 2005).

BICK, J.A., LANGE, B.M., Metabolic cross talk between cytosolic and plastidial pathways of isoprenoid biosynthesis unidirectional transport of intermediates across the chloroplast envelope membrane. Arch. Biochem. Biophys., 2003, 415, 146-154. 

The observations that flavonols are not involved in the fertilization process in certain species, and that this function can be completed using other compounds, suggest that flavonols only affect fertility indirectly. There are various examples of cross-talk between branch pathways of phenylpropanoid metabolism, or the shikimate pathway. The absence of flavonols in maize and Petunia could affect the accumulation of other compounds that are more specifically required for male fertility. Thus, differences between species in terms of flavonoid... 

Toumois C, Mutel V, Manivet P, Launay JM, Kellermann O. Cross-talk between 5-hydroxytryptamine receptors in a serotonergic cell line. Involvement of arachi-donic acid metabolism. J Biol Chem 1998 273 17,498—17,503. 

Again, the possibility of cross-talk exists between metabolic and genetic events. Thus, for example, steroids may bind to one receptor, which itself will interact with other proteins. Some of these proteins may be phosphorylated by kinases that respond to the presence of cAMP or a Ca2+ ion. 

This section reviews the current understanding of interspecific signal transfer mediated by small molecules that stimulate the initiation of secondary metabolism and cell differentiation in Streptomyces and related bacteria. In contrast to the deep understanding of intraspecific hormonal sensing, this research field is yet under development however, several new approaches have started to unveil the unseen nature of cross-talking in this group of bacteria. 

Yoshikawa T, Ide T, Shimano H, Yahagi N, Amemiya-Kudo M, Matsuzaka T, Yatoh S, Kitamine T, Okazaki H, Tamura Y, et al. Cross-talk between peroxisome proliferator-activated receptor (PPAR) alpha and liver X receptor (LXR) in nutritional regulation of fatty acid metabolism. I. PPARs suppress sterol regulatory element binding protein-Ic promoter through inhibition of LXR signaling. Mol. Endocrinol. 2003 17 1240-1254. 

In summary, the participation of the GPI/IPG system in cell activation by insulin is supported by the following evidences First, insulin induces tlie hydrolysis of GPI and the release of IPG second, impaired GPI metabolism or treatment with anti-IPG antibodies neutralize insulin actions and, third, natural and synthetic IPG have insulin-like activity. Several other diffusible factors activate GPI hydrolysis with the concomitant release of IPG. The next question is at which points IPG second messengers cross talk with the established signal transduction pathways. 

With these innovative sample introduction techniques, 96 samples can be analyzed in less than 20 min, which is compared to >2.5 h for traditional LC-MS/ MS. However, as in the case for the BioTrove s RapidFire system where no LC separation is involved, both techniques rely solely on the specificity of MS/ MS to differentiate different compounds. To take full advantage of FlashQuant and LDTD MS on complex system (e.g., hepatocyte incubation assay or in vivo studies), matrix effects, isobaric interferences, metabolic interferences, and MS cross-talk need to be carefully investigated prior to applying those techniques in samples analysis. 

---