Visualizing the spatial distribution and alteration of metabolites in continuously cropped Salvia miltiorrhiza Bge using MALDI-MSI

Salvia miltiorrhiza Bge(SMB)has long been used in traditional Chinese medicine to treat cardiovascular and cerebrovascular diseases.Growing clinical usage has led to a huge demand for artificial planting of SMB.Thus,continuous cropping of SMB is an important challenge that needs to be addressed.Continuous cropping can alter the metabolic profile of plants,resulting in poor growth and low yield.In this study,we tried to image the spatial location and variation of endogenous metabolites in continuously cropped SMB using matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDIMSI).Spatially resolved expressions of tanshinones,salvianolic acids,polyamines,phenolic acids,amino acids,and oligosaccharides in normal and continuously cropped SMB roots were compared.The expressions of dihydrotanshinone Ⅰ,tanshinone Ⅱ A,dehydromiltirone,miltirone,dehydrotanshinone ⅡA,spermine,salvianolic acid B/E,tetrasaccharide,and pentasaccharide in continuously cropped SMB roots were much lower than those in normal roots.There was little difference in the expressions of caffeic acid and salvianolic acid A in normal and continuously cropped SMB roots.Ferulic acid was more widely distributed in xylem of normal SMB but strongly expressed in xylem,phloem,and cambium of continuously cropped SMB.The spatially resolved metabolite information enhances our understanding of the metabolic signature of continuously cropped SMB and also provides insights into the metabolic effects of continuous cropping in other plants.

Developmental Lead Exposure Alters the Distribution of Protein Kinase C Activity in the Rat Hippocampus

Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activityt Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was obsereved in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.