Ingested energy differs between populations of the toad Bufo bankorensis from different altitudes

We measured ingested energy (E(i)) and apparent digestibility efficiency (ADE) in two populations of Bufo bankorensis from different altitudes at three temperatures and during two seasons to test the hypothesis that the optimal temperature range (T(opt)) for E(i) and ADE has shifted to the lower range in highland toads and winter toads. The T(opt) for E(i) was 22 degrees C for the lowland and highland toads and did not vary between seasons, thus falsifying the hypothesis. ADE of the toads was 96%-99% at 15 degrees -30 degrees C, and there was no difference between populations or seasons. Furthermore, when fed with fast-moving prey, the toads from both altitudes had similarly low E(i) at 15 degrees C; when fed with slow-moving prey, the highland toads increased E(i) at 15 degrees C, but the lowland toads did not. These results suggest that the toads from different altitudes had different appetites, even though their feeding locomotion was hampered in both populations at low temperatures.     

丹霞地貌山顶生态效应

首次探讨了丹霞地貌山顶生态效应现象,揭示特殊的地貌、形态所产生的特殊生态现象.测定广东省丹霞山宝珠峰和海螺峰的山顶的生态因子特征、群落结构特征和物种生态型特征,并与山脚的群落与种群以及相近非丹霞地貌区作比较.结果表明,山顶的平均温度高于山脚沟谷,平均湿度小于山脚沟谷,群落物种数和物种多样性均小于山脚沟谷.相比山顶而言,山脚沟谷的植物有很强的热带性.这些特征都有别于一般非丹霞地貌山地.另外,在山顶和山脚调查的几个种群在叶面积、比叶面积、树皮、枝下高和冠幅等方面,均出现了生态型的差异.讨论了丹霞地貌山顶对生态型研究、岛屿理论研究和适应性进化研究的科学意义.     

Synthesis and structure-activity relationship of 7-azaindole piperidine derivatives as CCR2 antagonists

The synthesis and structure-activity relationship of a series of 7-azaindole piperidine derivatives are described. SAR studies led to the discovery of the potent CCR2 antagonists displaying IC(50) values in the nanomolar range. The representative compound 15 showed reasonable P450 and pharmacokinetics profile.     

Crystal structure of Natratoxin, a novel snake secreted phospholipaseA2 neurotoxin from Naja atra venom inhibiting A-type K+ currents

Snake secreted phospholipasesA2 (sPLA2s) are widely used as pharmacological tools to investigate their role in diverse pathophysiological processes. Some members of snake venom sPLA2s have been found to block voltage-activated K(+) channels (K(v) channels). However, most studies involved in their effects on ion channels were indirectly performed on motor nerve terminals while few studies were directly done on native neurons. Here, a novel snake sPLA2 peptide neurotoxin, Natratoxin, composed of 119 amino acid residues and purified from Naja atra venom was reported. It was characterized using whole-cell patch-clamp in acutely dissociated rat dorsal root ganglion (DRG) neurons. It was found to effectively inhibit A-type K(+) currents and cause alterations of channel gating characters, such as the shifts of steady-state activation and inactivation curves to hyperpolarization direction and changes of V(1/2) and slope factor. Therefore, Natratoxin was suggested to be a gating modifier of K(v) channel. In addition, this inhibitory effect was found to be independent of its enzymatic activity. These results suggested that the toxin enacted its inhibitory effect by binding to K(v) channel. To further elucidate the structural basis for this electrophysiological phenomenon, we determined the crystal structure of Natratoxin at 2.2 A resolution by molecular replacement method and refined to an R-factor of 0.190. The observed overall fold has a different structural organization from other K(+) channel inhibitors in animal toxins. Compared with other K(v) channel inhibitors, a similar putative functional surface in its C-terminal was revealed to contribute to protein-protein interaction in such a blocking effect. Our results demonstrated that the spatial distribution of key amino acid residues matters most in the recognition of this toxin towards its channel target rather than its type of fold.     

Diploid parthenogenetic embryos adopt a maternal-type methylation pattern on both sets of maternal chromosomes

Epigenetic modifications are closely associated with embryo developmental potential. One of the epigenetic modifications thought to be involved in genomic imprinting is DNA methylation. Here we show that the maternally imprinted genes Snrpn and Peg1/Mest were nearly unmethylated or heavily methylated, respectively, in their differentially methylated regions (DMRs) at the two-cell stage in parthenogenetic embryos. However, both genes were gradually de novo methylated, with almost complete methylation of all CpG sites by the morula stage in parthenogenetic embryos. Unexpectedly, another maternally imprinted gene, Peg3, showed distinct dynamics of methylation during preimplantation development of diploid parthenogenetic embryos. Peg3 showed seemingly normal methylation patterns at the two-cell and morula stages, but was also strongly de novo methylated in parthenogenetic blastocysts. In contrast, the paternally imprinted genes H19 and Rasgrf1 showed complete unmethylation of their DMRs at the morula stage in parthenogenetic embryos. These results indicate that diploid parthenogenetic embryos adopt a maternal-type methylation pattern on both sets of maternal chromosomes and that the aberrantly homogeneous status of methylation imprints may partially account for developmental failure.     

N,N′-Ethylene-bis(3-methoxysalicylideneimine) mononuclear (4f) and heterodinuclear (3d–4f) metal complexes: Synthesis, crystal structure and luminescent properties

The stepwise synthesis of mononuclear (4f) and heterodinuclear (3d–4f) Salen-like complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, reactions of ligand H₂L and Ln(NO₃)₃ · 6H₂O give rise to three mononuclear lanthanide complexes Ln(H₂L)(NO₃)₃ [H₂L = N,N′-ethylene-bis(3-methoxysalicylideneimine), Ln = Nd (1), Eu (2) and Tb (3)], in which N,N′-ethylene-bis(3-methoxysalicylideneimine) acts as tetradentate ligands with the O₂O₂ set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac)₂ · H₂O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO₃)₃ · H₂O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N₂O₂ cavity. Luminescent analysis reveals that complex 3 exhibits characteristic metal-centered fluorescence of Tb(III) ion. However, the characteristic luminescence of both Sm(III) and Eu(III) ions is not observed both in solution and solid state of the complexes.     

大鼠隔区接受海马一氧化氮合酶(NOS)阳性神经元的投射

目的逆行追踪大鼠海马NOS阳性神经元向隔区的投射。方法用HRP逆行追踪与NADPH-d组化方法相结合进行研究。结果背、腹、后海马均有NOS阳性神经元投射至隔区各亚细胞群,后海马NOS阳性神经元向隔外侧核(sl)、隔三角核和隔伞核(ts,sf)的投射量,占后海马至隔外侧核、隔三角核和隔伞核投射量的80％左右。结论大鼠隔区接受海马NOS神经元的投射。     

Regulation of c-Jun N-terminal kinase activation in hydrogen peroxide induced neurotoxicity

C-Jun N-terminal kinase 1 and 2 (JNK1/2) have been shown to be transiently activated and involved in neurotoxicity. We searched for possible upstream molecules, which are responsible for the regulation of hydrogen peroxide-(H₂O₂) induced JNK1/2 activation and JNK1/2-mediated apoptotic-like cell death in cultured rat cortical neurons. The results showed that JNK1/2 activation (monitored by anti-diphosphorylated JNK1/2 antibody) was largely prevented by elimination of extracellular Ca²⁺ or blockage of NMDA-receptors (NMDA-R), and was weakly but significantly decreased by blockage of L-type voltage-gated calcium channel (L-VGCC); furthermore, JNK1/2 activation was largely prevented by inhibition of Ca²⁺/calmodulin-dependent protein kinase-II (CaMKII) and protein-tyrosine kinases (PTK). We also found that H₂O₂-induced apoptotic-like cell death was partially prevented by elimination of extracellular Ca²⁺, or by inhibition of NMDA-R, L-VGCC, PTK and CaMKII, respectively. The above results suggest that in H₂O₂-induced neurotoxicity, JNK1/2 activation is mainly mediated by NMDA-R and L-VGCC. Consequently, PTK and CaMKII are critical intermediaries in JNK1/2 activation and are mainly responsible for JNK1/2-mediated apoptotic-like cell death.     

Infusion of hESC derived Immunity‐and‐matrix regulatory cells improves cognitive ability in early‐stage AD mice

ObjectivesIn this study, we administered immunity‐and‐matrix regulatory cells (IMRCs) via tail vein (IV) and intracerebroventricular (ICV) injection to 3‐month‐old 5×FAD transgenic mice to assess the effects of IMRC transplantation on the behaviour and pathology of early‐stage Alzheimer''s disease (AD).Materials and methodsClinical‐grade human embryonic stem cell (hESC)‐derived IMRCs were produced under good manufacturing practice (GMP) conditions. Three‐month‐old 5×FAD mice were administered IMRCs via IV and ICV injection. After 3 months, the mice were subjected to behavioural tests and electrophysiological analysis to evaluate their cognitive function, memory ability and synaptic plasticity. The effect of IMRCs on amyloid‐beta (Aβ)‐related pathology was detected by thioflavin‐S staining and Western blot. Quantitative real‐time PCR, ELISA and immunostaining were used to confirm that IMRCs inhibit neuroinflammation. RNA‐seq analysis was performed to measure changes in gene expression and perform a pathway analysis in response to IMRC treatment.ResultsIMRC administration via tail vein injection significantly ameliorated cognitive deficits in early‐stage AD (5×FAD) mice. However, no significant change was observed in the characteristic pathology of AD in the ICV group. Plaque analysis revealed that IMRCs did not influence either plaque deposition or BACE1 expression. In addition, IMRCs inhibited inflammatory responses and reduced microglial activation in vivo.ConclusionsWe have shown that peripheral administration of IMRCs can ameliorate AD pathology and associated cognitive deficits.     

Characterization of the role of full-length CRMP3 and its calpain-cleaved product in inhibiting microtubule polymerization and neurite outgrowth

Collapsin response mediator proteins (CRMPs) are key modulators of cytoskeletons during neurite outgrowth in response to chemorepulsive guidance molecules. However, their roles in adult injured neurons are not well understood. We previously demonstrated that CRMP3 underwent calcium-dependent N-terminal protein cleavage during excitotoxicity-induced neurite retraction and neuronal death. Here, we report findings that the full-length CRMP3 inhibits tubulin polymerization and neurite outgrowth in cultured mature cerebellar granule neurons, while the N-terminal truncated CRMP3 underwent nuclear translocation and caused a significant nuclear condensation. The N-terminal truncated CRMP3 underwent nuclear translocation through nuclear pores. Nuclear protein pull-down assay and mass spectrometry analysis showed that the N-terminal truncated CRMP3 was associated with nuclear vimentin. In fact, nuclear-localized CRMP3 co-localized with vimentin during glutamate-induced excitotoxicity. However, the association between the truncated CRMP3 and vimentin was not critical for nuclear condensation and neurite outgrowth since over-expression of truncated CRMP3 in vimentin null neurons did not alleviate nuclear condensation and neurite outgrowth inhibition. Together, these studies showed CRMP3's role in attenuating neurite outgrowth possibility through inhibiting microtubule polymerization, and also revealed its novel association with vimentin during nuclear condensation prior to neuronal death.