摘要：Click chemistry was used to study on radiolabeling of 1,2,3-triazole analogs with fac-[188Re(CO)3(H2O)3]+. CuSO4/L-sodium ascorbate was chosen as the catalyst system, three terminal alkynes were conjugated with two different azides respectively, and then the new prepared fac-[188Re(CO)3(H2O)3]+ was coordinated to the six triazoles. The results showed that the radiochemical yields (RCY) of the conjugation of fac-[188Re(CO)3]+ with six triazoles were over 90%, and the triazoles showed high stability in phosphate-buffered saline and new-born calf serum. The preliminary biological evaluation results showed that the new 188Re-labeling method via click chemistry could have general application in labeling bioactive molecules in high radiochemical yield and high specific activity for further SPECT research.
摘要：Image distortion caused by angular misalignment of quadrupole magnets in high energy electron radiography is studied systematically. We propose that the distortion originates from the coupling of the motions of electron in transverse directions based on theoretical analysis via transfer matrix method. The relative angular rotation between the second and third magnetic quadrupoles is identified to be the main contributor to image distortion, which is verified by both beam dynamics simulation and experimental outcomes. In addition, different strategies to mitigate this image distortion are explored, including magnets online tuning, using higher beam energy and larger magnification factor. This study provides some criteria for designing experiments, and paves the way to achieve higher image precision.
摘要：The ability of animals to respond to life-threatening stimuli is essential for survival. Although vision provides one of the major sensory inputs for detecting threats across animal species, the circuitry underlying defensive responses to visual stimuli remains poorly defined. Here, we investigate the circuitry underlying innate defensive behaviours elicited by predator-like visual stimuli in mice. Our results demonstrate that neurons in the superior colliculus (SC) are essential for a variety of acute and persistent defensive responses to overhead looming stimuli. Optogenetic mapping revealed that SC projections to the lateral posterior nucleus (LP) of the thalamus, a non-canonical polymodal sensory relay, are sufficient to mimic visually evoked fear responses. In vivo electrophysiology experiments identified a di-synaptic circuit from SC through LP to the lateral amygdale (Amg), and lesions of the Amg blocked the full range of visually evoked defensive responses. Our results reveal a novel collicular-thalamic-Amg circuit important for innate defensive responses to visual threats.
摘要：Chromatin assembly in eukaryote is a well-organized process in which DNA and histone are hierarchically packaged into the nucleosome and chromatin. The assembly and disassembly of chromatin decode the genetic information stored within the chromatin. Histone variant and histone chaperone are major players in regulating the chromatin assembly and virtually involve in all DNA-based processes. In this review, we discuss the recent findings that provide insights into the assembly mechanism of histone variant H2A.Z and CENP-A, and highlight the important roleshistone chaperones play in this process.