Abscisic acid (ABA) plays an important role in plant growth and developmental processes. Although some ABA signal molecules, such as cADPR, Ca2+, etc., have been reported, there. was no evidence proving the involvemen...Abscisic acid (ABA) plays an important role in plant growth and developmental processes. Although some ABA signal molecules, such as cADPR, Ca2+, etc., have been reported, there. was no evidence proving the involvement of cAMP in A-B-A, signal transduction. In this present study, the constructed gene ( rd29A-GUS) was transformed into Nicotiana tabacum, and calli was induced from the transgenic plant. The suspension cells obtained from the callus grew well and uniformly. Treatment of the suspension cells with ABA led to an increase in GUS activity, indicating that these transgenic suspension cells are useful for the study of ABA signaling. Addition of nicotinamide (cADPR inhibitor) or U-73122 (phospholiphase C inhibitor) could only partially inhibit the increase of GUS activity elicited by ABA. The inhibitory effect of nicotinamide was enhanced by application of K252a (inhibitor of protein kinase). Treatment of the suspension cells with 8-Br-cAMP, a membrane-permeable analogue of cAMP, could partially replace the effect of ABA. Furthermore, intracellular addition of IBMX (phosphodiesterase inhibitor) mimicked die effect of exogenous cAMP on the deduction of expression of rd29A promoter. These results suggested that cAMP was an important messenger in ABA signal transduction in tobacco suspension cell.展开更多
Sp) Octyl 8 chloroadenosine 3′5′cyclophosphate (OCC), a newly synthesized 8 Cl c AMP derivative, strongly induced inhibition and differentiation in human leukemia HL 60 cells. In flow cytometry, OCC brought a...Sp) Octyl 8 chloroadenosine 3′5′cyclophosphate (OCC), a newly synthesized 8 Cl c AMP derivative, strongly induced inhibition and differentiation in human leukemia HL 60 cells. In flow cytometry, OCC brought about a block at the G1 phase of HL 60 cell cycle. OCC inhibited strongly the synthesis of DNA without affecting the synthesis of RNA and protein in HL 60 cells and also activated the c AMP dependent protein kinase in the cytosol of HL 60 cells. 8 Chloroadenosine is the active metabolite of OCC and inhibited significantly the growth of tumour in vitro and in vivo tests. 8 Chloroadenosine can induce differentiation of gastric mucoid adenocarcinoma cell line MGc80 3 and induce apoptosis in the MOLT 4 cells. The mechanism of the antitumour effects of 8 chloroadenosine was discussed.展开更多
Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, includi...Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, including an intact QS system 2 that is stimulated by the cyclic AMP （cAMP）-cAMP receptor protein （CRP） complex and a partial QS system 1 that consists of SdiA （suppressor of cell division inhibitor） responding to signals generated by other microbial species. The relationship between QS system 1 and system 2 in E. coli, however, remains obscure. Here, we show that an EAL domain protein, encoded by ydiV, and cAMP are involved in the interaction between the two QS systems in E. coli. Expression of sdiA and ydiV is inhibited by glucose. SdiA binds to the ydiV promoter region in a dose-dependent, but nonspecific, manner; extracellular autoinducer 1 from other species stimulates ydiV expression in an sdiA-depen- dent manner. Furthermore, we discovered that the double sdiA-ydiV mutation, but not the single mutation, causes a 2-fold decrease in intracellular cAMP concentration that leads to the inhibition of QS system 2. These results indicate that signaling pathways that respond to important environmental cues, such as autoinducers and glucose, are linked together for their control in E. coli.展开更多
The purpose of this contribution is to review our current understanding of the source and biochemistry of the circadian efferent input to the eyes of the American horseshoe crab Limuluspolyphemus and the impact of thi...The purpose of this contribution is to review our current understanding of the source and biochemistry of the circadian efferent input to the eyes of the American horseshoe crab Limuluspolyphemus and the impact of this input on the structure, physiology and biochemistry of Limulus eyes. Special emphasis is given to the role of the biogenic amine octopamine and bio- chemical cascades it activates in the eyes. In addition to reviewing published data, we present new data showing that octopamine elevates cAMP levels in Limulus lateral eyes, and we partially characterize the pharmacology of the receptors involved in this response. We also present new data showing that octopamine regulates gene expression in Limulus lateral eyes by activating a cAMP cascade展开更多
We measured sulfide-based ATP production by isolated mitochondria from four tissues of Urechis unicinctus and the effects of inhibitors of respiratory complexes on ATP production were evaluated. The results show that ...We measured sulfide-based ATP production by isolated mitochondria from four tissues of Urechis unicinctus and the effects of inhibitors of respiratory complexes on ATP production were evaluated. The results show that these mitochondria could oxidize sulfide to produce ATP. The yield of sulfide-stimulated ATP varied from 5 nmol ATP/min/mg to 90 nmol ATP/min/mg according to the sulfide concentration and the source of the mitochondria. The maximum ATP synthesis occurred in hindgut mitochondria using 5 μmol/L sulfide as a substrate. The effects of inhibitors (Rotenone, Antimycin A, Cyanide, and Salicylhydroxamic acid) on mitochondrial ATP production varied with the source of the mitochondria. Our results indicate that sulfide-based ATP production and the associated electron transport pathway are tissue-specific in U. unicinctus.展开更多
Pancreatic cells express the proglucagon gene （ gcg ） and thereby produce the peptide hormone glucagon , which stimulates hepa tic glucose production and thereby increases blood glucose levels. The same gcg gene is...Pancreatic cells express the proglucagon gene （ gcg ） and thereby produce the peptide hormone glucagon , which stimulates hepa tic glucose production and thereby increases blood glucose levels. The same gcg gene is also expressed in the intesti nal endocrine L cells and certain neural cells in the brain. In the gut, gcg expression leads to the production of glucagon-like peptide-1 （GLP-1）. This incretin hormone stimulates insulin secretion when blood glucose, level is high. In addition, GLP-1 stimulates pancreatic cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells.展开更多
文摘Abscisic acid (ABA) plays an important role in plant growth and developmental processes. Although some ABA signal molecules, such as cADPR, Ca2+, etc., have been reported, there. was no evidence proving the involvement of cAMP in A-B-A, signal transduction. In this present study, the constructed gene ( rd29A-GUS) was transformed into Nicotiana tabacum, and calli was induced from the transgenic plant. The suspension cells obtained from the callus grew well and uniformly. Treatment of the suspension cells with ABA led to an increase in GUS activity, indicating that these transgenic suspension cells are useful for the study of ABA signaling. Addition of nicotinamide (cADPR inhibitor) or U-73122 (phospholiphase C inhibitor) could only partially inhibit the increase of GUS activity elicited by ABA. The inhibitory effect of nicotinamide was enhanced by application of K252a (inhibitor of protein kinase). Treatment of the suspension cells with 8-Br-cAMP, a membrane-permeable analogue of cAMP, could partially replace the effect of ABA. Furthermore, intracellular addition of IBMX (phosphodiesterase inhibitor) mimicked die effect of exogenous cAMP on the deduction of expression of rd29A promoter. These results suggested that cAMP was an important messenger in ABA signal transduction in tobacco suspension cell.
文摘Sp) Octyl 8 chloroadenosine 3′5′cyclophosphate (OCC), a newly synthesized 8 Cl c AMP derivative, strongly induced inhibition and differentiation in human leukemia HL 60 cells. In flow cytometry, OCC brought about a block at the G1 phase of HL 60 cell cycle. OCC inhibited strongly the synthesis of DNA without affecting the synthesis of RNA and protein in HL 60 cells and also activated the c AMP dependent protein kinase in the cytosol of HL 60 cells. 8 Chloroadenosine is the active metabolite of OCC and inhibited significantly the growth of tumour in vitro and in vivo tests. 8 Chloroadenosine can induce differentiation of gastric mucoid adenocarcinoma cell line MGc80 3 and induce apoptosis in the MOLT 4 cells. The mechanism of the antitumour effects of 8 chloroadenosine was discussed.
文摘Quorum sensing （QS） is a bacterial cell-cell communication process by which bacteria communicate using extracellular signals called autoinducers. Two QS systems have been identified in Escherichia coli K-12, including an intact QS system 2 that is stimulated by the cyclic AMP （cAMP）-cAMP receptor protein （CRP） complex and a partial QS system 1 that consists of SdiA （suppressor of cell division inhibitor） responding to signals generated by other microbial species. The relationship between QS system 1 and system 2 in E. coli, however, remains obscure. Here, we show that an EAL domain protein, encoded by ydiV, and cAMP are involved in the interaction between the two QS systems in E. coli. Expression of sdiA and ydiV is inhibited by glucose. SdiA binds to the ydiV promoter region in a dose-dependent, but nonspecific, manner; extracellular autoinducer 1 from other species stimulates ydiV expression in an sdiA-depen- dent manner. Furthermore, we discovered that the double sdiA-ydiV mutation, but not the single mutation, causes a 2-fold decrease in intracellular cAMP concentration that leads to the inhibition of QS system 2. These results indicate that signaling pathways that respond to important environmental cues, such as autoinducers and glucose, are linked together for their control in E. coli.
基金supported by grants from the National Science Foundation (NSF)the Whitehall Foundation and the Whimey Laboratory
文摘The purpose of this contribution is to review our current understanding of the source and biochemistry of the circadian efferent input to the eyes of the American horseshoe crab Limuluspolyphemus and the impact of this input on the structure, physiology and biochemistry of Limulus eyes. Special emphasis is given to the role of the biogenic amine octopamine and bio- chemical cascades it activates in the eyes. In addition to reviewing published data, we present new data showing that octopamine elevates cAMP levels in Limulus lateral eyes, and we partially characterize the pharmacology of the receptors involved in this response. We also present new data showing that octopamine regulates gene expression in Limulus lateral eyes by activating a cAMP cascade
基金Supported by the National Natural Science Foundation of China (No. 40776074)
文摘We measured sulfide-based ATP production by isolated mitochondria from four tissues of Urechis unicinctus and the effects of inhibitors of respiratory complexes on ATP production were evaluated. The results show that these mitochondria could oxidize sulfide to produce ATP. The yield of sulfide-stimulated ATP varied from 5 nmol ATP/min/mg to 90 nmol ATP/min/mg according to the sulfide concentration and the source of the mitochondria. The maximum ATP synthesis occurred in hindgut mitochondria using 5 μmol/L sulfide as a substrate. The effects of inhibitors (Rotenone, Antimycin A, Cyanide, and Salicylhydroxamic acid) on mitochondrial ATP production varied with the source of the mitochondria. Our results indicate that sulfide-based ATP production and the associated electron transport pathway are tissue-specific in U. unicinctus.
基金Canadian Institutes of Health Research(CIHR,MOP-89987)Canadian Diabetes Association(CDA,2341)for providing funding support in conducting his current research on this topic.
文摘Pancreatic cells express the proglucagon gene （ gcg ） and thereby produce the peptide hormone glucagon , which stimulates hepa tic glucose production and thereby increases blood glucose levels. The same gcg gene is also expressed in the intesti nal endocrine L cells and certain neural cells in the brain. In the gut, gcg expression leads to the production of glucagon-like peptide-1 （GLP-1）. This incretin hormone stimulates insulin secretion when blood glucose, level is high. In addition, GLP-1 stimulates pancreatic cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells.
