The Experts below are selected from a list of 502731 Experts worldwide ranked by ideXlab platform
Shaofeng Liu - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of aluminum complexes bearing 8 anilide 5 6 7 trihydroquinoline ligands highly active catalyst precursors for ring opening polymerization of cyclic esters
Polymers, 2017Co-Authors: Shaofeng Liu, Jie Zhang, Weiwei Zuo, Wenjuan Zhang, Wenhua SunAbstract:The stoichiometric reactions of 8-(2,6-R1-4-R2-anilide)-5,6,7-trihydroquinoline (LH) with AlR3 (R = Me or Et) afforded the aluminum complexes LAlR2 (Al1–Al5,Al1: R1 = iPr, R2 = H, R = Me; Al2: R1 = Me, R2 = H, R = Me; Al3: R1 = H, R2 = H, R = Me; Al4: R1 = Me, R2 = Me, R = Me; Al5: R1 = Me, R2 = Me, R = Et) in high yields. All aluminum complexes were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Al4 and Al5 were determined by single-crystal X-ray diffractions and revealed a distorted tetrahedral geometry at aluminum. In the presence of BnOH, complexes Al1–Al5 efficiently initiated the ring-opening homopolymerization of e-caprolactone (e-CL) and rac-lactide (rac-LA), respectively, in a living/controlled manner.
-
Synthesis of Aluminum Complexes Bearing 8-Anilide-5,6,7-trihydroquinoline Ligands: Highly Active Catalyst Precursors for Ring-Opening Polymerization of Cyclic Esters
MDPI AG, 2017Co-Authors: Shaofeng Liu, Jie Zhang, Weiwei Zuo, Wenjuan Zhang, Wenhua SunAbstract:The stoichiometric reactions of 8-(2,6-R1-4-R2-anilide)-5,6,7-trihydroquinoline (LH) with AlR3 (R = Me or Et) afforded the aluminum complexes LAlR2 (Al1–Al5,Al1: R1 = iPr, R2 = H, R = Me; Al2: R1 = Me, R2 = H, R = Me; Al3: R1 = H, R2 = H, R = Me; Al4: R1 = Me, R2 = Me, R = Me; Al5: R1 = Me, R2 = Me, R = Et) in high yields. All aluminum complexes were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Al4 and Al5 were determined by single-crystal X-ray diffractions and revealed a distorted tetrahedral geometry at aluminum. In the presence of BnOH, complexes Al1–Al5 efficiently initiated the ring-opening homopolymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA), respectively, in a living/controlled manner
Thomas C Sudhof - One of the best experts on this subject based on the ideXlab platform.
-
high affinity neurexin binding to cell adhesion g protein coupled receptor cirl1 latrophilin 1 produces an intercellular adhesion complex
Journal of Biological Chemistry, 2012Co-Authors: Antony A. Boucard, Thomas C SudhofAbstract:The G-protein-coupled receptor CIRL1/latrophilin-1 (CL1) and the type-1 membrane proteins neurexins represent distinct neuronal cell adhesion molecules that exhibit no similarities except for one common function: both proteins are receptors for α-latrotoxin, a component of black widow spider venom that induces massive neurotransmitter release at synapses. Unexpectedly, we have now identified a direct binding interaction between the extracellular domains of CL1 and neurexins that is regulated by alternative splicing of neurexins at splice site 4 (SS4). Using saturation binding assays, we showed that neurexins lacking an insert at SS4 bind to CL1 with nanomolar affinity, whereas neurexins containing an insert at SS4 are unable to bind. CL1 competed for neurexin binding with neuroligin-1, a well characterized neurexin ligand. The extracellular sequences of CL1 contain five domains (lectin, olfactomedin-like, serine/threonine-rich, hormone-binding, and G-protein-coupled receptor autoproteolysis-inducing (GAIN) domains). Of these domains, the olfactomedin-like domain mediates neurexin binding as shown by deletion mapping. Cell adhesion assays using cells expressing neurexins and CL1 revealed that their interaction produces a stable intercellular adhesion complex, indicating that their interaction can be trans-cellular. Thus, our data suggest that CL1 constitutes a novel ligand for neurexins that may be localized postsynaptically based on its well characterized interaction with intracellular SH3 and multiple ankyrin repeats adaptor proteins (SHANK) and could form a trans-synaptic complex with presynaptic neurexins.
-
neuroligin 1 deletion results in impaired spatial memory and increased repetitive behavior
The Journal of Neuroscience, 2010Co-Authors: Jacqueline Blundell, Katsuhiko Tabuchi, Thomas C Sudhof, Cory A Blaiss, Mark R Etherton, Felipe Espinosa, Christopher Walz, Marc F Bolliger, Craig M PowellAbstract:Neuroligins (NLs) are a family of neural cell-adhesion molecules that are involved in excitatory/inhibitory synapse specification. Multiple members of the NL family (including NL1) and their binding partners have been linked to cases of human autism and mental retardation. We have now characterized NL1-deficient mice in autism- and mental retardation-relevant behavioral tasks. NL1 knock-out (KO) mice display deficits in spatial learning and memory that correlate with impaired hippocampal long-term potentiation. In addition, NL1 KO mice exhibit a dramatic increase in repetitive, stereotyped grooming behavior, a potential autism-relevant abnormality. This repetitive grooming abnormality in NL1 KO mice is associated with a reduced NMDA/AMPA ratio at corticostriatal synapses. Interestingly, we further demonstrate that the increased repetitive grooming phenotype can be rescued in adult mice by administration of the NMDA receptor partial coagonist d-cycloserine. Broadly, these data are consistent with a role of synaptic cell-adhesion molecules in general, and NL1 in particular, in autism and implicate reduced excitatory synaptic transmission as a potential mechanism and treatment target for repetitive behavioral abnormalities.
-
genetic analysis of alpha latrotoxin receptors reveals functional interdependence of cirl latrophilin 1 and neurexin 1 alpha
Journal of Biological Chemistry, 2002Co-Authors: Sönke Tobaben, Thomas C Sudhof, Bernd StahlAbstract:α-Latrotoxin triggers massive neurotransmitter release from nerve terminals by binding to at least two distinct presynaptic receptors, neurexin 1α and CIRL1/latrophilin1 (CL1). We have now generated knockout (KO) mice that lack CL1 and analyzed them alone or in combination with neurexin 1α KO mice. Mice lacking only CL1, or both CL1 and neurexin 1α, were viable and fertile. Ca2+-independent binding of α-latrotoxin to brain membranes was impaired similarly in CL1 single and in CL1/neurexin 1α double KO mice (∼75% decrease) but not in neurexin 1α single KO mice. In contrast, Ca2+-dependent binding (∼2 times above Ca2+-independent binding) was altered in both CL1 (∼50% decrease) and neurexin 1α single KO mice (∼25% decrease) and was decreased further in double KO mice (∼75% decrease). Synaptosomes lacking CL1 exhibited the same decrease in α-latrotoxin-stimulated glutamate release in the presence and absence of Ca2+(∼75%). In contrast, synaptosomes lacking neurexin 1α exhibited only a small decrease in α-latrotoxin-triggered release in the absence of Ca2+ (∼20%) but a major decrease in the presence of Ca2+ (∼75%). Surprisingly, synaptosomes lacking both CL1 and neurexin 1α displayed a relatively smaller decrease in α-latrotoxin-stimulated glutamate release than synaptosomes lacking only CL1 in the absence of Ca2+ (∼50versus ∼75%), but the same decrease in the presence of Ca2+ (∼75%). Our data suggest the following two major conclusions. 1) CL1 and neurexin 1α together account for the majority (75%) of α-latrotoxin receptors in brain, with the remaining receptor activity possibly due to other CL and neurexin isoforms, and 2) the two receptors act additively in binding α-latrotoxin but not in triggering release. Together these data suggest that the two receptors act autonomously in binding of α-latrotoxin but cooperatively in transducing the stimulation of neurotransmitter release by α-latrotoxin.
Wenhua Sun - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of aluminum complexes bearing 8 anilide 5 6 7 trihydroquinoline ligands highly active catalyst precursors for ring opening polymerization of cyclic esters
Polymers, 2017Co-Authors: Shaofeng Liu, Jie Zhang, Weiwei Zuo, Wenjuan Zhang, Wenhua SunAbstract:The stoichiometric reactions of 8-(2,6-R1-4-R2-anilide)-5,6,7-trihydroquinoline (LH) with AlR3 (R = Me or Et) afforded the aluminum complexes LAlR2 (Al1–Al5,Al1: R1 = iPr, R2 = H, R = Me; Al2: R1 = Me, R2 = H, R = Me; Al3: R1 = H, R2 = H, R = Me; Al4: R1 = Me, R2 = Me, R = Me; Al5: R1 = Me, R2 = Me, R = Et) in high yields. All aluminum complexes were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Al4 and Al5 were determined by single-crystal X-ray diffractions and revealed a distorted tetrahedral geometry at aluminum. In the presence of BnOH, complexes Al1–Al5 efficiently initiated the ring-opening homopolymerization of e-caprolactone (e-CL) and rac-lactide (rac-LA), respectively, in a living/controlled manner.
-
Synthesis of Aluminum Complexes Bearing 8-Anilide-5,6,7-trihydroquinoline Ligands: Highly Active Catalyst Precursors for Ring-Opening Polymerization of Cyclic Esters
MDPI AG, 2017Co-Authors: Shaofeng Liu, Jie Zhang, Weiwei Zuo, Wenjuan Zhang, Wenhua SunAbstract:The stoichiometric reactions of 8-(2,6-R1-4-R2-anilide)-5,6,7-trihydroquinoline (LH) with AlR3 (R = Me or Et) afforded the aluminum complexes LAlR2 (Al1–Al5,Al1: R1 = iPr, R2 = H, R = Me; Al2: R1 = Me, R2 = H, R = Me; Al3: R1 = H, R2 = H, R = Me; Al4: R1 = Me, R2 = Me, R = Me; Al5: R1 = Me, R2 = Me, R = Et) in high yields. All aluminum complexes were characterized by NMR spectroscopy and elemental analysis. The molecular structures of complexes Al4 and Al5 were determined by single-crystal X-ray diffractions and revealed a distorted tetrahedral geometry at aluminum. In the presence of BnOH, complexes Al1–Al5 efficiently initiated the ring-opening homopolymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA), respectively, in a living/controlled manner
Bernd Stahl - One of the best experts on this subject based on the ideXlab platform.
-
genetic analysis of alpha latrotoxin receptors reveals functional interdependence of cirl latrophilin 1 and neurexin 1 alpha
Journal of Biological Chemistry, 2002Co-Authors: Sönke Tobaben, Thomas C Sudhof, Bernd StahlAbstract:α-Latrotoxin triggers massive neurotransmitter release from nerve terminals by binding to at least two distinct presynaptic receptors, neurexin 1α and CIRL1/latrophilin1 (CL1). We have now generated knockout (KO) mice that lack CL1 and analyzed them alone or in combination with neurexin 1α KO mice. Mice lacking only CL1, or both CL1 and neurexin 1α, were viable and fertile. Ca2+-independent binding of α-latrotoxin to brain membranes was impaired similarly in CL1 single and in CL1/neurexin 1α double KO mice (∼75% decrease) but not in neurexin 1α single KO mice. In contrast, Ca2+-dependent binding (∼2 times above Ca2+-independent binding) was altered in both CL1 (∼50% decrease) and neurexin 1α single KO mice (∼25% decrease) and was decreased further in double KO mice (∼75% decrease). Synaptosomes lacking CL1 exhibited the same decrease in α-latrotoxin-stimulated glutamate release in the presence and absence of Ca2+(∼75%). In contrast, synaptosomes lacking neurexin 1α exhibited only a small decrease in α-latrotoxin-triggered release in the absence of Ca2+ (∼20%) but a major decrease in the presence of Ca2+ (∼75%). Surprisingly, synaptosomes lacking both CL1 and neurexin 1α displayed a relatively smaller decrease in α-latrotoxin-stimulated glutamate release than synaptosomes lacking only CL1 in the absence of Ca2+ (∼50versus ∼75%), but the same decrease in the presence of Ca2+ (∼75%). Our data suggest the following two major conclusions. 1) CL1 and neurexin 1α together account for the majority (75%) of α-latrotoxin receptors in brain, with the remaining receptor activity possibly due to other CL and neurexin isoforms, and 2) the two receptors act additively in binding α-latrotoxin but not in triggering release. Together these data suggest that the two receptors act autonomously in binding of α-latrotoxin but cooperatively in transducing the stimulation of neurotransmitter release by α-latrotoxin.
-
genetic analysis of α latrotoxin receptors reveals functional interdependence of cirl latrophilin 1 and neurexin 1α
Journal of Biological Chemistry, 2002Co-Authors: Sönke Tobaben, Bernd StahlAbstract:α-Latrotoxin triggers massive neurotransmitter release from nerve terminals by binding to at least two distinct presynaptic receptors, neurexin 1α and CIRL1/latrophilin1 (CL1). We have now generated knockout (KO) mice that lack CL1 and analyzed them alone or in combination with neurexin 1α KO mice. Mice lacking only CL1, or both CL1 and neurexin 1α, were viable and fertile. Ca2+-independent binding of α-latrotoxin to brain membranes was impaired similarly in CL1 single and in CL1/neurexin 1α double KO mice (∼75% decrease) but not in neurexin 1α single KO mice. In contrast, Ca2+-dependent binding (∼2 times above Ca2+-independent binding) was altered in both CL1 (∼50% decrease) and neurexin 1α single KO mice (∼25% decrease) and was decreased further in double KO mice (∼75% decrease). Synaptosomes lacking CL1 exhibited the same decrease in α-latrotoxin-stimulated glutamate release in the presence and absence of Ca2+(∼75%). In contrast, synaptosomes lacking neurexin 1α exhibited only a small decrease in α-latrotoxin-triggered release in the absence of Ca2+ (∼20%) but a major decrease in the presence of Ca2+ (∼75%). Surprisingly, synaptosomes lacking both CL1 and neurexin 1α displayed a relatively smaller decrease in α-latrotoxin-stimulated glutamate release than synaptosomes lacking only CL1 in the absence of Ca2+ (∼50versus ∼75%), but the same decrease in the presence of Ca2+ (∼75%). Our data suggest the following two major conclusions. 1) CL1 and neurexin 1α together account for the majority (75%) of α-latrotoxin receptors in brain, with the remaining receptor activity possibly due to other CL and neurexin isoforms, and 2) the two receptors act additively in binding α-latrotoxin but not in triggering release. Together these data suggest that the two receptors act autonomously in binding of α-latrotoxin but cooperatively in transducing the stimulation of neurotransmitter release by α-latrotoxin.
-
Genetic analysis of alpha-latrotoxin receptors reveals functional interdependence of CIRL/latrophilin 1 and neurexin 1 alpha
The Journal of biological chemistry, 2001Co-Authors: Sönke Tobaben, Bernd StahlAbstract:Abstract α-Latrotoxin triggers massive neurotransmitter release from nerve terminals by binding to at least two distinct presynaptic receptors, neurexin 1α and CIRL1/latrophilin1 (CL1). We have now generated knockout (KO) mice that lack CL1 and analyzed them alone or in combination with neurexin 1α KO mice. Mice lacking only CL1, or both CL1 and neurexin 1α, were viable and fertile. Ca2+-independent binding of α-latrotoxin to brain membranes was impaired similarly in CL1 single and in CL1/neurexin 1α double KO mice (∼75% decrease) but not in neurexin 1α single KO mice. In contrast, Ca2+-dependent binding (∼2 times above Ca2+-independent binding) was altered in both CL1 (∼50% decrease) and neurexin 1α single KO mice (∼25% decrease) and was decreased further in double KO mice (∼75% decrease). Synaptosomes lacking CL1 exhibited the same decrease in α-latrotoxin-stimulated glutamate release in the presence and absence of Ca2+(∼75%). In contrast, synaptosomes lacking neurexin 1α exhibited only a small decrease in α-latrotoxin-triggered release in the absence of Ca2+ (∼20%) but a major decrease in the presence of Ca2+ (∼75%). Surprisingly, synaptosomes lacking both CL1 and neurexin 1α displayed a relatively smaller decrease in α-latrotoxin-stimulated glutamate release than synaptosomes lacking only CL1 in the absence of Ca2+ (∼50versus ∼75%), but the same decrease in the presence of Ca2+ (∼75%). Our data suggest the following two major conclusions. 1) CL1 and neurexin 1α together account for the majority (75%) of α-latrotoxin receptors in brain, with the remaining receptor activity possibly due to other CL and neurexin isoforms, and 2) the two receptors act additively in binding α-latrotoxin but not in triggering release. Together these data suggest that the two receptors act autonomously in binding of α-latrotoxin but cooperatively in transducing the stimulation of neurotransmitter release by α-latrotoxin.
Dong Jiang - One of the best experts on this subject based on the ideXlab platform.
-
nitrogen topdressing timing modifies free amino acids profiles and storage protein gene expression in wheat grain
BMC Plant Biology, 2018Co-Authors: Yingxin Zhong, Kim Henrik Hebelstrup, Donglei Yang, Jian Cai, Xiao Wang, Qin Zhou, Weixing Cao, Tingbo Dai, Dong JiangAbstract:Nitrogen is one basic element of amino acids and grain protein in wheat. In field experiments, wheat plants were subjected to different timing of nitrogen topdressing treatments: at the stages of emergence of the top fifth leaf (TL5), top third leaf (TL3) and top first leaf (TL1) to test the regulatory effects of nitrogen topdressing timing on grain protein quality. The underlying mechanisms were elucidated by clarifying the relationship between proteolysis in vegetative organs and accumulation of amino acids in the endosperm cavity, conversion of amino acids, and storage protein synthesis in endosperm of wheat grain. Delayed nitrogen topdressing up-regulated gene expression related to nitrogen metabolism and protease synthesis in the flag leaf, followed by more free amino acids being transported to both the cavity and the endosperm from 7 days after anthesis (DAA) to 13 DAA in TL1. TL1 enhanced the conversion between free amino acids in endosperm and upregulated the expression of genes encoding high molecular weight (HMW) and low molecular weight (LMW) subunits and protein disulfide isomerases-like (PDIL) proteins, indicating that the synthesis and folding of glutenin were enhanched by delayed nitrogen topdressing. As a consequense, the content of glutenin macropolymers (GMP) and glutenin increased with delaying nitrogen topdressing. The results highlight the relationship between nitrogen remobilization and final grain protein production and suggest that the nitrogen remobilization processes could be a potential target for improving the quality of wheat grain. Additionally, specific gene expression related to nitrogen topdressing was identified, which conferred more detailed insights into underlying mechanism on the modification protein quality.
-
Nitrogen topdressing timing modifies free amino acids profiles and storage protein gene expression in wheat grain
BMC, 2018Co-Authors: Yingxin Zhong, Kim Henrik Hebelstrup, Donglei Yang, Jian Cai, Xiao Wang, Qin Zhou, Weixing Cao, Tingbo Dai, Dong JiangAbstract:Abstract Background Nitrogen is one basic element of amino acids and grain protein in wheat. In field experiments, wheat plants were subjected to different timing of nitrogen topdressing treatments: at the stages of emergence of the top fifth leaf (TL5), top third leaf (TL3) and top first leaf (TL1) to test the regulatory effects of nitrogen topdressing timing on grain protein quality. The underlying mechanisms were elucidated by clarifying the relationship between proteolysis in vegetative organs and accumulation of amino acids in the endosperm cavity, conversion of amino acids, and storage protein synthesis in endosperm of wheat grain. Results Delayed nitrogen topdressing up-regulated gene expression related to nitrogen metabolism and protease synthesis in the flag leaf, followed by more free amino acids being transported to both the cavity and the endosperm from 7 days after anthesis (DAA) to 13 DAA in TL1. TL1 enhanced the conversion between free amino acids in endosperm and upregulated the expression of genes encoding high molecular weight (HMW) and low molecular weight (LMW) subunits and protein disulfide isomerases-like (PDIL) proteins, indicating that the synthesis and folding of glutenin were enhanched by delayed nitrogen topdressing. As a consequense, the content of glutenin macropolymers (GMP) and glutenin increased with delaying nitrogen topdressing. Conclusions The results highlight the relationship between nitrogen remobilization and final grain protein production and suggest that the nitrogen remobilization processes could be a potential target for improving the quality of wheat grain. Additionally, specific gene expression related to nitrogen topdressing was identified, which conferred more detailed insights into underlying mechanism on the modification protein quality