Enzymatic glucose biosensor based on CeO2 nanorods synthesized by non-isothermal precipitation

Cerium oxide nanorods (CeO(2) NRs) were synthesized without templates through a low cost and simple non-isothermal precipitation method. The structure and morphology of CeO(2) NRs were characterized by X-ray diffraction and transmission electron microscopy. The CeO(2) NRs films, deposited on indium tin oxide (ITO)-coated glass substrates through electrophoretic deposition, were used for the immobilization of glucose oxidase (GOx). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterize the CeO(2) NRs/ITO and GOx/CeO(2) NRs/ITO electrodes. The GOx/CeO(2) NRs/ITO electrode exhibits a linear range for the detection of glucose from 2 to 26 mM (correlation coefficient: 0.99) at 1-2s response time. Biosensor sensitivity is 0.165 μA mM(-1) cm(-2) with 100 μM detection limit. The anti-interference ability of the biosensor was also examined. The mediator-less application of CeO(2) NRs for glucose sensing was demonstrated.     

基于NDVI的云南省自然保护区保护成效分析

保护成效评估是自然保护区管理和优化的重要基础。选取云南省国家级和省级自然保护区,以SPOT_Vegetation提供的归一化植被指数（Normalized Difference Vegetation Index,简写NDVI）,基于NDVI变化趋势（采用一元线性趋势法）和NDVI变化稳定性（采用变异系数法）,比较分析了自然保护区内外的植被生长状况,评估了自然保护区的保护成效。结果表明：（1）1998-2015年,云南省国家级和省级自然保护区内、外部NDVI总体呈显著增长,内、外部NDVI呈显著增长的自然保护区分别占总数的64.81%、79.63%,体现自然保护区总体具有较好的保护成效,其集中分布于滇中、滇东北及滇东南。（2）云南省国家级和省级自然保护区内、外部NDVI变异系数无显著性差异,51.85%的自然保护区内部植被长势比其外部稳定,具有较好的保护成效,其主要分布在滇西、滇西南、滇东南和滇东北,但未能反映出自然保护区带来的保护成效的内外部明显的分异。（3）云南省国家级自然保护区的保护成效总体上要好于省级自然保护区。（4）就不同类型的自然保护区而言,森林生态类自然保护区保护成效较好,野生植物类和野生动物类保护成效一般,湿地生态类较差。该研究能为区域自然保护地保护成效评价方法的探索提供参考,研究结果可以为云南省自然保护区优化和完善提供支撑。     

圆唇散白蚁工蚁生殖可塑性相关的性腺发育和基因表达

【目的】为了探讨圆唇散白蚁Reticulitermes labralis雌性工蚁向补充生殖蚁转化过程中的卵巢发育特征以及卵母细胞从滞育到恢复生长发育的起点。【方法】观察圆唇散白蚁雌性工蚁从3龄-6龄-转化成补充生殖蚁发育过程中的卵巢和卵母细胞动态变化;在若蚁向原始生殖蚁和补充生殖蚁转化的转录组中筛选出与卵母细胞生长期相关的基因表达,利用qRT-PCR方法检测这些基因在工蚁向生殖蚁转化发育过程中的表达水平。【结果】圆唇散白蚁工蚁从低龄向老龄发育过程中卵巢逐渐增大;前补充生殖蚁卵巢长度和宽度分别是工蚁的约2和3倍,而前补充生殖蚁转化为补充生殖蚁之后,卵巢没有显著增大。工蚁转化为前补充生殖蚁之后,卵母细胞大小（长径）和滤泡细胞层厚度仍然没有显著改变;前补充生殖蚁转化成补充生殖蚁之后,卵母细胞大小和滤泡细胞层厚度显著增加。调控卵母细胞生长期发育的6个基因cyclin-dependent kinase 1, cell division cycle protein 20, G2/mitotic-specific cyclin-B3, G2/mitotic-specific cyclin-A, aurora kinase A和serine/threonine-protein kinasepolo在补充生殖蚁中的表达水平极显著增加,分别是前补充生殖蚁的约34, 62, 91, 36, 57和106倍。工蚁转化为前补充生殖蚁之后,仅G2/mitotic-specific cyclin-B3, G2/mitotic-specific cyclin-A和aurora kinase A表达水平显著增高,分别是工蚁的约3, 3和2倍。【结论】圆唇散白蚁工蚁卵巢发育的停滞发生在老龄期,卵母细胞发育的恢复和减数分裂启动从工蚁转化为补充生殖蚁之后开始。     

Identification of a binding motif specific to HNF4 by comparative analysis of multiple nuclear receptors

Nuclear receptors (NRs) regulate gene expression by binding specific DNA sequences consisting of AG[G/T]TCA or AGAACA half site motifs in a variety of configurations. However, those motifs/configurations alone do not adequately explain the diversity of NR function in vivo. Here, a systematic examination of DNA binding specificity by protein-binding microarrays (PBMs) of three closely related human NRs--HNF4α, retinoid X receptor alpha (RXRα) and COUPTF2--reveals an HNF4-specific binding motif (H4-SBM), xxxxCAAAGTCCA, as well as a previously unrecognized polarity in the classical DR1 motif (AGGTCAxAGGTCA) for HNF4α, RXRα and COUPTF2 homodimers. ChIP-seq data indicate that the H4-SBM is uniquely bound by HNF4α but not 10 other NRs in vivo, while NRs PXR, FXRα, Rev-Erbα appear to bind adjacent to H4-SBMs. HNF4-specific DNA recognition and transactivation are mediated by residues Asp69 and Arg76 in the DNA-binding domain; this combination of amino acids is unique to HNF4 among all human NRs. Expression profiling and ChIP data predict ≈ 100 new human HNF4α target genes with an H4-SBM site, including several Co-enzyme A-related genes and genes with links to disease. These results provide important new insights into NR DNA binding.     

Nuclear receptor profile in calvarial bone cells undergoing osteogenic versus adipogenic differentiation

Nuclear receptors (NRs) are key regulators of cell function and differentiation. We examined NR expression during osteogenic versus adipogenic differentiation of primary mouse calvarial osteoblasts (MOBs). MOBs were cultured for 21 days in osteogenic or adipogenic differentiation media. von Kossa and Oil Red O staining, and qRT-PCR of marker genes and 49 NRs were performed. PCR amplicons were subcloned to establish correct sequences and absolute standard curves. Forty-three NRs were detected at days 0-21. Uncentered average linkage hierarchical clustering identified four expression clusters: NRs (1) upregulated during osteogenic, but not adipogenic, differentiation, (2) upregulated in both conditions, with greater upregulation during adipogenic differentiation, (3) upregulated equally in both conditions, (4) downregulated during adipogenic, but not osteogenic, differentiation. One-way ANOVA with contrast revealed 20 NRs upregulated during osteogenic differentiation and 12 NRs upregulated during adipogenic differentiation. Two-way ANOVA demonstrated that 18 NRs were higher in osteogenic media, while 9 NRs were higher in adipogenic media. The time effect revealed 16 upregulated NRs. The interaction of condition with time revealed 6 NRs with higher expression rate during adipogenic differentiation and 3 NRs with higher expression rate during osteogenic differentiation. Relative NR abundance at days 0 and 21 were ranked. Basal ranking changed at least 5 positions for 13 NRs in osteogenic media and 9 NRs in adipogenic media. Osteogenic and adipogenic differentiation significantly altered NR expression in MOBs. These differences offer a fingerprint of cellular commitment and may provide clues to the underlying mechanisms of osteogenic versus adipogenic differentiation.     

Changes in Nuclear Receptor and Vitellogenin Gene Expression in Response to Steroids and Heavy Metal in Caenorhabditis elegans

To gain basic understanding of the reproductive and developmental effects of endocrine disrupting chemicals in invertebrates, we have used C. elegans as an animal model. The completion of the C. elegans genome sequence brings to bear microarray analysis as a tool for these studies. We previously showed that the C. elegans genome was responsive to vertebrate steroid hormones, and changes in gene expression of traditional biomarkers used in environmental studies were detected; i.e., vitellogenin (vtg), cytochrome P450 (cyp450), glutathione-S-transferase (gst) and heat shock proteins (hsp). The data were interpreted to suggest that exogenous lipophilic compounds can be metabolized via cytochrome P450 proteins, and that the resulting metabolites can bind to members of the Nuclear Receptor (NR) class of proteins and regulate gene expression. In the present study, using DNA microarrays, we examined the pattern of gene expression after progesterone (10(-5), 10(-7) M), estradiol (10(-5) M), cholesterol (10(-9) M) and cadmium (0.1, 1 and 10 μM) exposure, with special attention to the members of NRs. Of approximately 284 NRs in C. elegans, expression of 25 NR genes (representing 9% of the total NRs in C. elegans) was altered after exposure to steroids. Of note, each steroid activated or inhibited different subsets of NR genes, and only estradiol regulated NR genes implicated in neurogenesis. These results suggest that NRs respond to a variety of exogenous steroids, which regulate important metabolic and developmental pathways. The response of the C. elegans genome to cholesterol and cadmium was analyzed in more detail. Cholesterol is a probable precursor to signaling molecules that may interact with NRs and we focused on expression of genes related to lipid metabolism (cyp450), transport and storage (i.e., vitellogenin). Worms exposed to cadmium respond principally by activating the expression of genes encoding stress-responsive proteins, such as mtl-2 and cdr-1, and no significant changes in expression of NRs or vtg genes were observed. The possible implications of these results with regard to the evolution of steroid receptors, endocrine disruption and the role of vitellogenin as a lipid transporter are discussed.     

Molecular characterization of SMILE as a novel corepressor of nuclear receptors

SMILE (small heterodimer partner interacting leucine zipper protein) has been identified as a coregulator in ER signaling. In this study, we have examined the effects of SMILE on other NRs (nuclear receptors). SMILE inhibits GR, CAR and HNF4α-mediated transactivation. Knockdown of SMILE gene expression increases the transactivation of the NRs. SMILE interacts with GR, CAR and HNF4α in vitro and in vivo. SMILE and these NRs colocalize in the nucleus. SMILE binds to the ligand-binding domain or AF2 domain of the NRs. Competitions between SMILE and the coactivators GRIP1 or PGC-1α have been demonstrated in vitro and in vivo. Furthermore, an intrinsic repressive activity of SMILE is observed in Gal4-fusion system, and the intrinsic repressive domain is mapped to the C-terminus of SMILE, spanning residues 203–354. Moreover, SMILE interacts with specific HDACs (histone deacetylases) and SMILE-mediated repression is released by HDAC inhibitor trichostatin A, in a NR-specific manner. Finally, ChIP (chromatin immunoprecipitation) assays reveal that SMILE associates with the NRs on the target gene promoters. Adenoviral overexpression of SMILE represses GR-, CAR- and HNF4α-mediated target gene expression. Overall, these results suggest that SMILE functions as a novel corepressor of NRs via competition with coactivators and the recruitment of HDACs.     

Identification of nuclear receptors involved in regulation of male reproduction in the red flour beetle, Tribolium castaneum

Nineteen canonical and two Knirps-like family nuclear receptors (NRs) were identified in the genome of Tribolium castaneum. The current study was conducted to identify NRs involved in regulation of male reproduction. RNA interference (RNAi)-aided knockdown in the expression of genes coding for all 21 NRs showed that reduction in the levels of 11 NRs (E75, E78, FTZ-F1, HR38, HR4, Knirps-like, HNF4, Tailless, HR51, Dsf and HR39) in the male beetles caused more than 50% reduction in the eggs laid by the female beetles mated with RNAi male beetles. Among these 11 NRs that are required for male reproduction, knockdown in the expression of genes coding for E78 and HR39 in the male beetles resulted in a reduction in the number of sperm produced and transferred to the female when compared to the sperms produced and transferred by the control male beetles injected with bacterial malE dsRNA. In contrast, knockdown in the expression of genes coding for E75 and HR38 caused a reduction in the size of male accessory glands (MAG), the amount of protein produced by the MAG and the expression of genes coding for accessory gland proteins. These data suggest that NRs such as E78 and HR39 regulate sperm production and their transfer to the females and the other NRs such as E75 and HR38 regulate the development of MAG and the production of accessory gland proteins.     

NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPARβ/δ signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPARβ/δ and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.