Many plant cells respond to pathogens by the induction of phytoalexin biosynthesis, but the underlying changes of gene expression are often obscured by their close linkage to the complex rearrangements during pathogen...Many plant cells respond to pathogens by the induction of phytoalexin biosynthesis, but the underlying changes of gene expression are often obscured by their close linkage to the complex rearrangements during pathogen defense, especially the hypersensitive cell death. In root-derived cell cultures of Eschscholzia californica, the overproduction of cytotoxic benzophenanthridine alkaloids can be triggered by a minimum of pathogen pressure that does not evoke hypersensitive reactions. Such conditions activate a signal chain that is initiated by a short contact to low concentrations of yeast glycoprotein elicitor and includes a transient acidification of the cytoplasm. In contrast, high elicitor concentrations signal via an increase of jasmonate and trigger hypersensitive cell death, preceded by a drastic decay of translatable mRNAs. The main changes in protein and mRNA patterns caused by either signal path were compared by 2D proteomic separation, MS/MS sequencing and mRNA-in vitro translation. The four proteins showing the highest overexpression were identical between cells that received low or high-elicitor treatment and overlapped with the three proteins most upregulated by artificial pH shifts. They comprised one biosynthetic enzyme （norcoclaurine：SAM 4＇ O-methyl-transferase） plus a unique combination of stress-protective proteins： a heat shock protein （hsp 70）; a peptidyl-prolyl-cis/trans isomerase （cyclophilin）; and a glyceraldehyde-3-phosphate dehydrogenase. It appears that overproduction of the benzophenanthri- dine phytoalexins requires the up-regulation of a rate-limiting biosynthetic enzyme plus the coordinated expression of a specific set of protective enzymes and thus is managed like an oxidative stress.展开更多
The maximum rates of adenosine triphosphatase （ATPase） systems related to energy consumption were systematically evaluated in synaptic plasma membranes isolated from the striata of male Wistar rats aged 2, 6, 12, 18...The maximum rates of adenosine triphosphatase （ATPase） systems related to energy consumption were systematically evaluated in synaptic plasma membranes isolated from the striata of male Wistar rats aged 2, 6, 12, 18, and 24 months, because of their key role in presynaptic nerve ending homeostasis. The following enzyme activities were evaluated： sodium-potassium-magnesium adenosine triphosphatase （Na^＋, K^＋, Mg^2＋-ATPase）; ouabain-insensitive magnesium adenosine triphosphatase （Mg^2＋-ATPase）; sodium-potassium adenosine triphosphatase （Na^＋, K^＋-ATPase）; direct magnesium adenosine triphosphatase （Mg^2＋-ATPase）; calcium-magnesium adenosine triphosphatase （Ca^2＋, Mg^2＋-ATPase）; and acetylcholinesterase. The results showed that Na~, K＋-ATPase decreased at 18 and 24 months, Ca^2＋, Mg^2＋-ATPase and acetylcholinesterase decreased from 6 months, while Mg^2＋-ATPase was unmodified. Therefore, ATPases vary independently during aging, suggesting that the ATPase enzyme systems are of neuropathological and pharmacological importance. This could be considered as an experimental model to study regeneration processes, because of the age-dependent modifications of specific synaptic plasma membranes. ATPases cause selective changes in some cerebral functions, especially bioenergetic systems. This could be of physiopathological significance, particularly in many central nervous system diseases, where, during regenerative processes, energy availability is essential.展开更多
文摘Many plant cells respond to pathogens by the induction of phytoalexin biosynthesis, but the underlying changes of gene expression are often obscured by their close linkage to the complex rearrangements during pathogen defense, especially the hypersensitive cell death. In root-derived cell cultures of Eschscholzia californica, the overproduction of cytotoxic benzophenanthridine alkaloids can be triggered by a minimum of pathogen pressure that does not evoke hypersensitive reactions. Such conditions activate a signal chain that is initiated by a short contact to low concentrations of yeast glycoprotein elicitor and includes a transient acidification of the cytoplasm. In contrast, high elicitor concentrations signal via an increase of jasmonate and trigger hypersensitive cell death, preceded by a drastic decay of translatable mRNAs. The main changes in protein and mRNA patterns caused by either signal path were compared by 2D proteomic separation, MS/MS sequencing and mRNA-in vitro translation. The four proteins showing the highest overexpression were identical between cells that received low or high-elicitor treatment and overlapped with the three proteins most upregulated by artificial pH shifts. They comprised one biosynthetic enzyme （norcoclaurine：SAM 4＇ O-methyl-transferase） plus a unique combination of stress-protective proteins： a heat shock protein （hsp 70）; a peptidyl-prolyl-cis/trans isomerase （cyclophilin）; and a glyceraldehyde-3-phosphate dehydrogenase. It appears that overproduction of the benzophenanthri- dine phytoalexins requires the up-regulation of a rate-limiting biosynthetic enzyme plus the coordinated expression of a specific set of protective enzymes and thus is managed like an oxidative stress.
文摘The maximum rates of adenosine triphosphatase （ATPase） systems related to energy consumption were systematically evaluated in synaptic plasma membranes isolated from the striata of male Wistar rats aged 2, 6, 12, 18, and 24 months, because of their key role in presynaptic nerve ending homeostasis. The following enzyme activities were evaluated： sodium-potassium-magnesium adenosine triphosphatase （Na^＋, K^＋, Mg^2＋-ATPase）; ouabain-insensitive magnesium adenosine triphosphatase （Mg^2＋-ATPase）; sodium-potassium adenosine triphosphatase （Na^＋, K^＋-ATPase）; direct magnesium adenosine triphosphatase （Mg^2＋-ATPase）; calcium-magnesium adenosine triphosphatase （Ca^2＋, Mg^2＋-ATPase）; and acetylcholinesterase. The results showed that Na~, K＋-ATPase decreased at 18 and 24 months, Ca^2＋, Mg^2＋-ATPase and acetylcholinesterase decreased from 6 months, while Mg^2＋-ATPase was unmodified. Therefore, ATPases vary independently during aging, suggesting that the ATPase enzyme systems are of neuropathological and pharmacological importance. This could be considered as an experimental model to study regeneration processes, because of the age-dependent modifications of specific synaptic plasma membranes. ATPases cause selective changes in some cerebral functions, especially bioenergetic systems. This could be of physiopathological significance, particularly in many central nervous system diseases, where, during regenerative processes, energy availability is essential.
