基于核心家系的EGR3基因与精神分裂症的关联研究

研究表明位于染色体8p21.3区域的EGR3(Early growth response 3)是精神分裂症(Schizophrenia)的重要易感基因,然而,仍有两个病例-对照研究未能验证上述发现。为了研究EGR3基因在我国患者中是否与疾病关联,文章在中国汉族的核心家系中选择EGR3基因座位上的5个SNPs位点(rs1996147、rs1877670、rs3750192、rs35201266和rs7009708)进行基因分型和传递不平衡检验(Transmission disequilibrium test,TDT)。结果表明遗传标记rs1996147和rs3750192分别显示出显著的传递不平衡(2>4.40,P<0.05)。在连锁不平衡分析中,由2个(rs3750192和rs35201266)、3个(rs1877670、rs3750192和rs7009708)以及4个(rs1996147、rs1877670、rs3750192和rs7009708)SNPs位点构建的单倍型均显示与精神分裂症显著性关联(2>7.10,整体P<0.05)。总之,EGR3基因与中国汉族人群精神分裂症遗传易感性相关,后续关于EGR3基因进一步的功能研究将会更好的帮助我们了解该基因在疾病病理学机制中的作用。     

Cat fertilization by mouse sperm injection

Summary Interspecies intracytoplasmic sperm injection has been carried out to understand species-specific differences in oocyte environments and sperm components during fertilization. While sperm aster organization during cat fertilization requires a paternally derived centriole, mouse and hamster fertilization occur within the maternal centrosomal components. To address the questions of where sperm aster assembly occurs and whether complete fertilization is achieved in cat oocytes by interspecies sperm, we studied the fertilization processes of cat oocytes following the injection of cat, mouse, or hamster sperm. Male and female pronuclear formations were not different in the cat oocytes at 6 h following cat, mouse or hamster sperm injection. Microtubule asters were seen in all oocytes following intracytoplasmic injection of cat, mouse or hamster sperm. Immunocytochemical staining with a histone H3-m2K9 antibody revealed that mouse sperm chromatin is incorporated normally with cat egg chromatin, and that the cat eggs fertilized with mouse sperm enter metaphase and become normal 2-cell stage embryos. These results suggest that sperm aster formation is maternally dependent, and that fertilization processes and cleavage occur in a non-species specific manner in cat oocytes.     

Specificity for inhibitors of metal-substituted methionine aminopeptidase

Methionine aminopeptidases (MetAPs) have been studied in vitro as Co(II) enzymes, but their in vivo metal remains to be defined. While activation of Escherichia coli MetAP (EcMetAP1) by Co(II), Mn(II), and Zn(II) was detectable by a colorimetric Met-S-Gly-Phe assay, significant activation by Ni(II) was shown in a fluorescence Met-AMC assay, in addition to Co(II) and Mn(II) activation. When tested on the metal-substituted EcMetAP1s, a few inhibitors that we obtained recently from a random screening on Co-EcMetAP1 either became much weak or lost activity on Mn- or Zn-EcMetAP1, although they kept inhibitory activity on Ni-EcMetAP1. A couple of peptidic inhibitors and the methionine mimetic (3R)-amino-(2S)-hydroxyheptanoic acid (AHHpA, 6) maintained moderate activities on Co-, Mn-, Zn-, and Ni-EcMetAP1s. Our results clearly demonstrate that the metal-substitution has changed the enzyme specificity for substrates and inhibitors. Therapeutic applications call for inhibitors specific for MetAP with a physiologically relevant metal at its active site.     

Low intraspecific diversity in a polynucleobacter subcluster population numerically dominating bacterioplankton of a freshwater pond

Cultivation-dependent and -independent methods were combined to investigate the microdiversity of a Polynucleobacter subcluster population (Betaproteobacteria) numerically dominating the bacterioplankton of a small, humic freshwater pond. Complete coverage of the population by cultivation allowed the analysis of microdiversity beyond the phylogenetic resolution of ribosomal markers. Fluorescent in situ hybridization with two probes specific for the narrow subcluster C (PnecC bacteria) of the Polynucleobacter cluster revealed that this population contributed up to 60% to the total number of bacterioplankton cells. Microdiversity was investigated for a date at which the highest relative numbers of PnecC were observed. A clone library of fragments of the ribosomal operon (16S rRNA genes, complete 16S-23S internal transcribed spacer 1 [ITS1], partial 23S rRNA genes) amplified with universal bacterial primers was constructed. The library was stepwise screened for fragments from PnecC bacteria and for different ITS genotypes of PnecC bacteria. The isolated PnecC strains were characterized by sequencing of the 16S rRNA genes and the ITS1. Both the clone library and the established culture collection contained only the same three ITS genotypes, and one of them contributed 46% to the entire number of clones. Genomic fingerprinting of the isolates with several methods always resulted in the detection of only one fingerprint per ITS genotype. We conclude that a Polynucleobacter population with an extremely low intraspecific diversity and an uneven structure numerically dominated the bacterioplankton community in the investigated habitat. This low intraspecific diversity is in strong contrast to the high intraspecific diversities found in marine bacterial populations.     

Synthesis, biological evaluation, and molecular docking studies of N-((1,3-diphenyl-1H-pyrazol-4-yl)methyl)aniline derivatives as novel anticancer agents

A series of N-((1,3-diphenyl-1H-pyrazol-4-yl)methyl)aniline derivatives (5a-8d) have been designed and synthesized, and their biological activities were also evaluated as potential antitumor and cyclin dependent kinase 2 (CDK2) inhibitors. Among all the compounds, compound 5a displayed the most potent CDK2/cyclin E inhibitory activity in vitro, with an IC(50) of 0.98±0.06μM. Antitumor assays indicated that compound 5a owned high antiproliferative activity against MCF-7 and B16-F10 cancer cell lines with IC(50) values of 1.88±0.11 and 2.12±0.15μM, respectively. Docking simulation was performed to insert compound 5a into the crystal structure of CDK2 at active site to determine the probable binding model. Based on the preliminary results, compound 5a with potent inhibitory activity in tumor growth may be a potential anticancer agent.     

Inhibitors of type I MetAPs containing pyridine-2-carboxylic acid thiazol-2-ylamide. Part 2: SAR studies on the pyridine ring 3-substituent

Systematic SAR studies on the pyridine ring 3-substituent of PCAT, an inhibitor of EcMetAP1 and ScMetAP1, revealed that 3-substituents have different selectivity for EcMetAP1 and ScMetAP1. The selective inhibitors of type I MetAP are useful tools for investigating the detailed interactions between the enzymes and their inhibitors. In addition, these findings provide useful information for the design and discovery of more potent inhibitors of type I MetAPs.     

Structural and functional characterization of ryanodine receptor-natrin toxin interaction

Cysteine-rich secretory proteins (CRISPs) are widely distributed, and notably occur in the mammalian reproductive tract and in the salivary glands of venomous reptiles. Most CRISPs can inhibit ion channels, such as the cyclic nucleotide-gated ion channel, potassium channel, and calcium channel. Natrin is a CRISP that has been purified from snake venom. Its targets include the calcium-activated potassium channel, the voltage-gated potassium channel, and the calcium release channel/ryanodine receptor (RyR). Immunoprecipitation experiments showed that natrin binds specifically to type 1 RyR (RyR1) from skeletal muscle. Natrin was found to inhibit both the binding of ryanodine to RyR1, and the calcium-channel activity of RyR1. Cryo-electron microscopy and single-particle image reconstruction analysis revealed that natrin binds to the clamp domains of RyR1. Docking of the crystal structure of natrin into our cryo-electron microscopy density map of the RyR1 + natrin complex suggests that natrin inhibits RyR1 by stabilizing a domain-domain interaction, and that the cysteine-rich domain of natrin is crucial for binding. These findings help reveal how natrin toxin inhibits the RyR calcium release channel, and they allow us to posit a generalized mechanism that governs the interaction between CRISPs and ion channels.