14-3-3epsilon is important for neuronal migration by binding to NUDEL: a molecular explanation for Miller-Dieker syndrome

Heterozygous deletions of 17p13.3 result in the human neuronal migration disorders isolated lissencephaly sequence (ILS) and the more severe Miller-Dieker syndrome (MDS). Mutations in PAFAH1B1 (the gene encoding LIS1) are responsible for ILS and contribute to MDS, but the genetic causes of the greater severity of MDS are unknown. Here, we show that the gene encoding 14-3-3epsilon (YWHAE), one of a family of ubiquitous phosphoserine/threonine-binding proteins, is always deleted in individuals with MDS. Mice deficient in Ywhae have defects in brain development and neuronal migration, similar to defects observed in mice heterozygous with respect to Pafah1b1. Mice heterozygous with respect to both genes have more severe migration defects than single heterozygotes. 14-3-3epsilon binds to CDK5/p35-phosphorylated NUDEL and this binding maintains NUDEL phosphorylation. Similar to LIS1, deficiency of 14-3-3epsilon results in mislocalization of NUDEL and LIS1, consistent with reduction of cytoplasmic dynein function. These results establish a crucial role for 14-3-3epsilon in neuronal development by sustaining the effects of CDK5 phosphorylation and provide a molecular explanation for the differences in severity of human neuronal migration defects with 17p13.3 deletions.     

Direct observation of a local thermal vibration anomaly in a quasicrystal

Quasicrystals have long-range order with symmetries that are incompatible with periodicity, and are often described with reference to a higher-dimensional analogue of a periodic lattice. Within the context of this 'hyperspace' crystallography, lattice dynamics of quasicrystals can be described by a combination of lattice vibrations and atomic fluctuations--phonons and phasons. However, it is difficult to see localized fluctuations in a real-space quasicrystal structure, and so the nature of phason-related fluctuations and their contribution to thermodynamic stability are still not fully understood. Here we use atomic-resolution annular dark-field scanning transmission electron microscopy to map directly the change in thermal diffuse scattering intensity distribution in the quasicrystal, through in situ high-temperature observation of decagonal Al72Ni20Co8. We find that, at 1,100 K, a local anomaly of atomic vibrations becomes significant at specific atomic sites in the structure. The distribution of these localized vibrations is not random but well-correlated, with a quasiperiodic length scale of 2 nm. We are able to explain this feature by an anomalous temperature (Debye-Waller) factor for the Al atoms that sit at the phason-related sites defined within the framework of hyperspace crystallography. The present results therefore provide a direct observation of local thermal vibration anomalies in a solid.     

Effects of brain monoamine depletion on thermoregulation,active avoidance,and food and water intake in rats

Summary Intraventricular administration of 6-OHDA or 5,6-DHT suppressed food intake, whereas their effect on active avoidance produced a suppression with the former and an enhancement with the latter. The increased water intake was specifically associated with 5,6-DHT treatment in rats.This work supported by grants from the National Science Council (Republic of China), J. Aron Charitable Foundation (USA) and John B. Pierce Foundation (USA). The authors are grateful to Drs C.Y. Chai and H. H. Lu for their support and advice.     

固氮酶活性中心模型的EHMO研究

应用群分解BHMO程序,研究了含S_2的固氮酶活性中心模型和N_2的络合活化模式.结果表明,在结构参数优化的情况下,平躺式络合与微斜插入式络合的键能差别不大(前者仅高约1ev),实际的络合方式很可能是直插式的或微斜插入式的,这样在加进1个H或两个H后,μ_3-H_2就转化为端基络合在Mo上的-N=NH或=N-NH_2。对奇数电子体系,由于其LUMO和NHOMO之间能级差别小,如对称性相同,易于产生d—d跃迁,从而为S=3/2的实验事实提供了可能的解释.     

甲烷氧化偶联Ba－ZrO_2催化剂的研究

发现掺有碱土金属组份的ＺｒＯ２样品形成ＡＺｒＯ３相，其对甲烷氧化偶联反应显示出相当好的催化活性和选择性（其中Ａ＝Ｃａ，Ｓｒ，Ｂａ，尤以Ｂａ为佳）．大量ＢａＣＯ３相的存在有利于进一步提高催化剂的选择性；对于９０ｍｏｌ％Ｂａ－ＺｒＯ２催化剂在７５０℃，６００００ｍｌ·ｇ－１·ｈ－１，ＣＨ４：Ｏ２：Ｎ２＝３．８：１．０：９．０（摩尔比）的条件下，Ｃ２烃选择性为５６．９％，Ｃ２烃得率达１７．２％．讨论了ＢａＣＯ３对几种催化剂的促进作用．     

碱土金属氟化物／三氧化二钆催化剂的甲烷氧化偶联性能

考察碱土金属氟化物／三氧化二钆在甲烷氧化偶联反应中的催化性能．发现在Ｇｄ＿２Ｏ＿３中添加碱土金属氟化物，Ｃ＿２选择性和收率都有明显提高。当Ｇｄ＿２Ｏ＿３摩尔含量相同时，催化性能按Ｃａ－Ｓｒ－Ｂａ顺序递增，在８０％ＢａＦ＿２／Ｇｄ＿２Ｏ＿３催化剂上Ｃ＿２选择性和收率分别达５９．５％和１８．７％．ＸＲＤ分析结果表明，在含氟催化剂中出现了四方Ｇｄ＿４Ｏ＿３Ｆ＿６新相，其结构与立方ＣａＦ＿２，ＳｒＦ＿２和ＢａＦ＿２相似．可能有利于物相之间的匹配及载流子传递．ＸＰＳ测试发现，催化剂表面上存在着（或Ｏ￣－）物种．与Ｇｄ＿２Ｏ＿３相比，在含氟的催化剂中，Ｏ＿１ｓ结合能较高，表明该吸附氧物种所带电荷较少，对提高Ｃ＿２选择性有利。     

低压铜基甲醇含成催化剂活性表面的XPS和TPD表征

对用共沉淀法制备并经氢预还原活化的三组份 Cu-ZnO-Al_2O_3 和四组份Cu-ZnO-Al_2O_3-M_2O_3(M=Sc~(3+)、Cr~(3+)或In~(3+))铜基甲醇合成催化剂进行 XPS,XPS-Augcr,TPD谱表征及CO吸附量测定,研究铜基甲醇合成催化剂活性表面铜的化学态。根据原子价补偿原理及本实验结果,在温和还原条件下,催化剂活性表面存在少量Cu~+,它是 CO、H_2 的吸附活性位。