二倍体和三倍体太平洋牡蛎鳃扫描电镜的比较

利用扫描电子显微镜技术对二倍体和三倍体太平洋牡蛎(Crassostrea gigas)鳃的表面结构进行了观察和比较。结果显示：三倍体牡蛎鳃丝的宽度、鳃丝间的距离较二倍体大;鳃丝的微细结构比二倍体更致密;鳃丝间通过丝问连接形成的孔洞大于二倍体。这些不同表明二倍体和三倍体呼吸及摄食可能存在差异。     

Deficient neurogenesis in forebrain-specific presenilin-1 knockout mice is associated with reduced clearance of hippocampal memory traces.

To examine the in vivo function of presenilin-1 (PS1), we selectively deleted the PS1 gene in excitatory neurons of the adult mouse forebrain. These conditional knockout mice were viable and grew normally, but they exhibited a pronounced deficiency in enrichment-induced neurogenesis in the dentate gyrus. This reduction in neurogenesis did not result in appreciable learning deficits, indicating that addition of new neurons is not required for memory formation. However, our postlearning enrichment experiments lead us to postulate that adult dentate neurogenesis may play a role in the periodic clearance of outdated hippocampal memory traces after cortical memory consolidation, thereby ensuring that the hippocampus is continuously available to process new memories. A chronic, abnormal clearance process in the hippocampus may conceivably lead to memory disorders in the mammalian brain.     

无机元素对紫杉醇和紫杉烷类化合物生物合成的调控作用

利用细胞培养生产此杉醇是重要的生产途径之一,但是,由于紫杉醇含量低,已经成为世界级研究难题。因此,紫杉醇的生物合成调控成为研究热点。Ｍｇ＾＋＋有利于紫杉醇的合成,并促进１０－去乙酰浆果赤霉素Ⅲ和浆果赤霉素Ⅲ向紫杉醇转化。Ｃｕ＾＋＋抑制紫杉醇及紫杉烷类化合物的合成。适量的Ｆｅ＾＋＋可以促进紫杉醇的合成,但较高或产低浓度的Ｆｅ＾＋＋均抑制１０－去乙酰浆果赤霉素Ⅲ和浆果赤霉素Ⅲ向紫杉醇转化。     

Identification of dynamic signatures associated with smoking‐related squamous cell lung cancer and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a risk factor for the development of lung cancer. The aim of this study was to identify early diagnosis biomarkers for lung squamous cell carcinoma (SQCC) in COPD patients and to determine the potential pathogenetic mechanisms. The GSE12472 data set was downloaded from the Gene Expression Omnibus database. Differentially co‐expressed links (DLs) and differentially expressed genes (DEGs) in both COPD and normal tissues, or in both SQCC + COPD and COPD samples were used to construct a dynamic network associated with high‐risk genes for the SQCC pathogenetic process. Enrichment analysis was performed based on Gene Ontology annotations and Kyoto Encyclopedia of Genes and Genomes pathway analysis. We used the gene expression data and the clinical information to identify the co‐expression modules based on weighted gene co‐expression network analysis (WGCNA). In total, 205 dynamic DEGs, 5034 DLs and one pathway including CDKN1A, TP53, RB1 and MYC were found to have correlations with the pathogenetic progress. The pathogenetic mechanisms shared by both SQCC and COPD are closely related to oxidative stress, the immune response and infection. WGCNA identified 11 co‐expression modules, where magenta and black were correlated with the “time to distant metastasis.” And the “surgery due to” was closely related to the brown and blue modules. In conclusion, a pathway that includes TP53, CDKN1A, RB1 and MYC may play a vital role in driving COPD towards SQCC. Inflammatory processes and the immune response participate in COPD‐related carcinogenesis.     

DREB1A类转录调控域中对转录激活功能起关键作用的氨基酸

从烟草品种k326中克隆到2个干旱应答元件结合蛋白类(DREB-Like)转录因子基因,命名为NtDREBI和NtDREB1A.序列分析发现,NtDREBI和NtDREB1A编码的蛋白质具有典型的AP2/EREBP转录因子家族EREBP亚族A类特征.酵母单杂交结果显示,NtDREBI具有激活功能, 而NtDREB1A不能激活下游基因,但可以与DRE元件结合.将NtDREBI、NtDREB1A与其它AP2/EREBP类转录因子序列比对,发现在C末端第148位氨基酸有显著差别.采用定点突变方法进一步研究表明,DREB1A类转录因子的第148位氨基酸残基与其邻近氨基酸残基的相互作用对调控转录激活功能起关键作用.     

Studies of the Mo(V) Center of the Y343F Mutant of Human Sulfite Oxidase by Variable Frequency Pulsed EPR Spectroscopy

The Mo(V) forms of the Tyr343Phe (Y343F) mutant of human sulfite oxidase (SO) have been investigated by continuous wave (CW) and variable frequency pulsed EPR spectroscopies as a function of pH. The CW EPR spectrum recorded at low-pH (∼6.9) has g-values similar to those known for the low-pH form of the native vertebrate SO (original lpH form); however, unlike the spectrum of original lpH SO, it does not show any hyperfine splittings from a nearby exchangeable proton. The detailed electron spin echo (ESE) envelope modulation (ESEEM) and pulsed electron-nuclear double resonance (ENDOR) experiments also did not reveal any nearby protons that could belong to an exchangeable ligand at the molybdenum center. These results suggest that under low-pH conditions the active site of Y343F SO is in the “blocked” form, with the Mo(V) center coordinated by sulfate. With increasing pH the EPR signal from the “blocked” form decreases, while a signal similar to that of the original lpH form appears and becomes the dominant signal at pH >9. In addition, both the CW EPR and ESE-detected field-sweep spectra reveal a considerable contribution from a signal similar to that usually detected for the high-pH form of native vertebrate SO (original hpH form). The nearby exchangeable protons in both of the component forms observed at high-pH were studied by the ESEEM spectroscopy. These results indicate that the Y343F mutation increases the apparent pK_a of the transition from the lpH to hpH forms by ∼2 pH units.     

Direct electrochemistry and electrocatalysis of heme proteins immobilized on gold nanoparticles stabilized by chitosan

Three heme proteins, myoglobin, hemoglobin, and cytochrome c, have been adsorbed onto chitosan-stabilized gold nanoparticles (Chit-Aus) modified Au electrode via a molecule bridge like cysteine. UV-vis spectra indicated that the proteins on Chit-Aus films retained near-native secondary structures. The fabricated procedures and electrochemical behaviors of proteins on such an interface were characterized with electrochemical impedance spectra and cyclic voltammetric techniques. It was demonstrated that Chit-Aus film could not only offer a friendly environment to immobilize protein molecules but also enhance the electron transfer ability between protein molecules and underlying electrode. The effects of scan rate and pH on the electrochemical behaviors of each heme protein are discussed in detail. The resultant electrode displayed an excellent electrocatalytic response to the reduction of H(2)O(2), long-term stability, and good reproducibility.     

The kinetic study of arginine kinase from the sea cucumber Stichopus japonicus with 5,5'-dithiobis-(2-nitrobenzoic acid)

The Stichopus japonicus arginine kinase (AK) is a significant dimeric enzyme. Its modification and inactivation course with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) and the reactivation course of DTNB-modified AK by dithiothreitol were investigated on the basis of the kinetic theory of the substrate reaction during the modification of enzyme activity. The results show that the modification is a biphasic course while the inactivation is monophasic, with one essential reactive cysteine per subunit. The Cys274 (numbering from the Stichopus sequence) is exposed to DTNB and is near the ATP binding site. The modified AK can be reactivated by an excess concentration of dithiothreitol in a monophasic kinetic course. The presence of ATP or the transition-state analog markedly slows the apparent reactivation rate constant. The analog components, arginine-ADP-Mg2+ can induce conformational changes of the modified enzyme, but adding NO3- cannot induce further changes that occur with the native enzyme. The reactive cysteines' location and its role in the catalysis of AK are discussed. The results suggest that the cysteine may be located in the hinge area of the two domains of AK. The reactive cysteine of AK, which was proposed to be Cys274, may play an important role not in the binding of the transition-state analog but in the conformational changes caused by the transition-state analog.     

Molecular characterization of FK-506 binding protein 38 and its potential regulatory role on the anti-apoptotic protein Bcl-2

The immunosuppressant FK-506 binding protein 38 (FKBP38) is localized at the mitochondrial membrane and appears to play an important role in apoptosis. Recent reports about the potential functions of FKBP38 in apoptosis appear to be controversial. To further understand the biological function of FKBP38, here, we studied its molecular characteristics and a potential regulatory role on the anti-apoptotic protein Bcl-2. Our results suggest that FKBP38 appears to show chaperone activities in the citrate synthase aggregation assays during thermal denaturation and affect solubility of Bcl-2 when they are co-expressed. The FKBP family proteins bind the immunosuppressive drug FK-506 through the FK-506 binding domain and consequently inhibit the activity of calcineurin. In this study, from our NMR studies and calcineurin assays in vitro, we demonstrate that the N-terminal fragment of FKBP38 which contains the FK-506 binding domain does not bind FK-506 at molecular level. Lastly, to investigate the effect of FKBP38 on Bcl-2, we suppressed FKBP38 by RNA interference (RNAi) of FKBP38. Our results suggest that the suppression of FKBP38 appears to make Bcl-2 unstable or unprotected from degradation in an unknown mechanism.     

Receptor activator of NF-kappaB (RANK) cytoplasmic motif, 369PFQEP373, plays a predominant role in osteoclast survival in part by activating Akt/PKB and its downstream effector AFX/FOXO4

Receptor activator of NF-kappaB ligand (RANKL) plays a crucial role in osteoclast differentiation, function, and survival. RANKL exerts its effect by activating its receptor RANK (receptor activator of NF-kappaB), which recruits various intracellular signaling molecules via specific motifs in its cytoplasmic tail. Previously, we identified three RANK cytoplasmic motifs (Motif 1, 369PFQEP373; Motif 2, 559PVQEET564; and Motif 3, 604PVQEQG609) mediating osteoclast formation and function. Here, we investigated RANK cytoplasmic motifs involved in osteoclast survival. Motif 1, in contrast to its minimal role in osteoclast formation and function, plays a predominant role in promoting osteoclast survival. Moreover, whereas Motif 2 and Motif 3 are highly potent in osteoclast formation and function, they exert a moderate effect on osteoclast survival. We also investigated the role of these motifs in activating Akt/protein kinase B (PKB), which has been implicated in RANKL-induced osteoclast survival. Motif 1, but not Motif 2 or Motif 3, is able to stimulate Akt/PKB activation. Because Akt/PKB has been shown to utilize distinct downstream effectors (glycogen synthase kinase-3beta, FKHR/FOXO1a, BAD, and AFX/FOXO4) to regulate cell survival, we next determined which downstream effector(s) is activated by Akt/PKB to promote osteoclast survival. Our data revealed that RANKL only stimulates AFX/FOXO4 phosphorylation, indicating that AFX/FOXO4 is a key downstream target activated by Akt/PKB to modulate osteoclast survival. Taken together, we conclude that Motif 1 plays a predominant role in mediating osteoclast survival in part by activating Akt/PKB and its downstream effector AFX/FOXO4.