Isolation and characterization of dengue virus serotype 2 from the large dengue outbreak in Guangdong,China in 2014

Dengue has been well recognized as a global public health threat,but only sporadic epidemics and imported cases were reported in recent decades in China.Since July 2014,an unexpected large dengue outbreak has occurred in Guangdong province,China,resulting in more than 40000 patients including six deaths.To clarify and characterize the causative agent of this outbreak,the acute phase serum from a patient diagnosed with severe dengue was subjected to virus isolation and high-throughput sequencing(HTS).Traditional real-time RT-PCR and HTS with Ion Torrent PGM detected the presence of dengue virus serotype 2(DENV-2).A clinical DENV-2 isolate GZ05/2014 was obtained by culturing the patient serum in mosquito C6/36 cells.The complete genome of GZ05/2014 was determined and deposited in Gen Bank under the access number KP012546.Phylogenetic analysis based on the complete envelope gene showed that the newly DENV-2 isolate belonged to Cosmopolitan genotype and clustered closely with other Guangdong strains isolated in the past decade.No amino acid mutations that are obviously known to increase virulence or replication were identified throughout the genome of GZ05/2014.The high homology of Guangdong DENV-2 strains indicated the possibility of establishment of local DENV-2 circulation in Guangdong,China.These results help clarify the origin of this epidemic and predict the future status of dengue in China.     

The tumor suppressor p53 can reduce stable transfection in the presence of irradiation

The tumor suppressor p53 is believed to play an essential role in maintaining genome stability. Although it is currently unknown how p53 is involved in this important biological safeguard, several previous publications indicate that p53 can help to maintain genome integrity through the recombination-mediated DNA repair process. The integration of linearized plasmid DNA into the host chromosome utilizes the same repair process, and the frequency can be measured by clonogenic assays in which cells that were stably transfected by plasmid integration can be scored by their colony-forming abilities. To gain insight into whether p53 has a direct role in plasmid integration into the host chromosome, we determined the frequency of stable transfection with CHO cells expressing either wild-type or mutant p53 in the presence and absence of irradiation. We found that low-dose irradiation (50 to 100 cGy) increased stable transfection frequencies in CHO cells regardless of their p53 status. However, the increase of transfection frequency was significantly lower in CHO cells expressing wild-type p53. Our data thus suggest that wild-type p53 can suppress plasmid DNA integration into the host genome. This p53 function may play a direct and significant role in maintaining genome stability.     

5—羟色胺抑制谷氨酸对海马神经元的毒性作用

为探讨5-羟色胺（5-HT）对过量谷氨酸（glutamate,Glu)神经毒性的影响。观察了5-HT存在时,过量Glu对海马细胞存活率、海马脑片CA1区群锋电位（population spike,PS)及神经细胞膜Ga^2 电流的影响。结果发现：5-HT可明显提高过量Glu作用下海马神经细胞的存活率,减缓Glu对海马脑片CA1区PS的降低作用;在细胞膜上,5-HT可明显减弱Glu诱导的Ca^2 内向电流,推测,一定浓度的5-HT具有抑制过量Glu神经毒性的作用。在细胞膜上5-HT可明显减弱Glu诱导的Ca^2 内向电流,推测,一定浓度的5-HT具有抑制过量Glu神经毒性的作用,其机制可能在于5-HT与细胞膜上特定的受体结合,抑制了Glu诱导的Ca^2 内流。     

Transforming growth factor-β1 suppresses hepatitis B virus replication by the reduction of hepatocyte nuclear factor-4α expression

Several studies have demonstrated that cytokine-mediated noncytopathic suppression of hepatitis B virus (HBV) replication may provide an alternative therapeutic strategy for the treatment of chronic hepatitis B infection. In our previous study, we showed that transforming growth factor-beta1 (TGF-β1) could effectively suppress HBV replication at physiological concentrations. Here, we provide more evidence that TGF-β1 specifically diminishes HBV core promoter activity, which subsequently results in a reduction in the level of viral pregenomic RNA (pgRNA), core protein (HBc), nucleocapsid, and consequently suppresses HBV replication. The hepatocyte nuclear factor 4alpha (HNF-4α) binding element(s) within the HBV core promoter region was characterized to be responsive for the inhibitory effect of TGF-β1 on HBV regulation. Furthermore, we found that TGF-β1 treatment significantly repressed HNF-4α expression at both mRNA and protein levels. We demonstrated that RNAi-mediated depletion of HNF-4α was sufficient to reduce HBc synthesis as TGF-β1 did. Prevention of HNF-4α degradation by treating with proteasome inhibitor MG132 also prevented the inhibitory effect of TGF-β1. Finally, we confirmed that HBV replication could be rescued by ectopic expression of HNF-4α in TGF-β1-treated cells. Our data clarify the mechanism by which TGF-β1 suppresses HBV replication, primarily through modulating the expression of HNF-4α gene.     

猫扣带回前部内脏伤害感受神经元的膜电学特性

目的：研究猫扣带回前部内脏大神经刺激相关神经元的膜电生理特性,以便从神经元水平进一步了解大脑皮质内脏伤害感受的特性及机制,为痛觉理论“特异性学说”提供新的实验依据。方法：应用在体玻璃微电极细胞内电位记录技术及细胞内注入极化电流的方法,测量和计算神经元的膜电学参数。结果：将20只猫扣带回前部176个内脏大神经刺激相关神经元,分为内脏伤害(148个)和非伤害(28个)感受神经元。发现它们在膜电阻、时间常数、膜电容及I—V曲线等方面存在差异。注入去极化电流引发的放电幅值及频率也存在差异。结论：扣带回前部内脏伤害与非伤害感受神经元可能在细胞膜结构、细胞大小等形态学方面存有差别。     

GABA神经元在金黄地鼠视觉中枢的分布

本文用免疫细胞化学技术研究了GABA在金黄地鼠视觉中枢的分布特征,同时用统计学方法作了定量分析,结果表明:GABA阳性神经元分布在整个视皮层和上丘中,呈不均匀分布,外膝体中GABA阳性神经元密度较低.视皮层中GABA阳性神经元密度为781mm~2,占视皮层细胞总数的19.7%,上丘中其密度为812/mm~2,占22.3%,视皮层Ⅰ层中GABA阳性神经元为52%,上丘表层(浅灰层及视觉层GABA阳性神经元为56%,GABA阳性神经元包括不同类型的细胞.在视皮层中可观察到GABA免疫疫应阳性的锥体细胞.     

生石膏对致热原作用下猫PO／AH温敏神经元放电的影响

目的:研究中药生石膏解热作用的中枢机制.方法:复制发热模型后,静脉注射生石膏,应用微电极细胞外记录技术记录视前区-下丘脑前部(PO/AH) 温敏神经元单位放电的变化情况.结果:给予致热原后,PO/AH 区热敏神经元放电频率显著减少(P<0.01 ),冷敏神经元放电频率明显增加(P<0.05); 静脉注射生石膏后,可反转致热原对PO/AH区温敏神经元的上述作用,与给药前相比,热敏神经元放电频率明显回升(P<0.01 ),冷敏神经元放电频率明显回降(P<0.05).结论:提示生石膏是通过影响致热原作用下PO/AH区温敏神经元的放电活动,在中枢神经元水平上发挥解热作用的.     

怀孕前后酒精摄入对雌鼠植入前胚胎DNA甲基化模式建立的影响

女性怀孕前后饮酒会对胎儿的发育及神经系统造成不利影响,称为“胎儿酒精综合征”（fetal alcohol spectrum disorders,FASD）。小鼠通常作为研究该病的动物模型。该实验采用体外培养技术及体内冲胚法研究雌鼠怀孕前后酒精摄入对各期植入前胚胎全基因组DNAT基化模式建立的影响。小鼠植入前胚胎体外培养实验发现,体外实验组I（怀孕前酒精处理组1,除8-cell外,其他各期胚胎的DNA甲基化水平明显低于体外对照组;体外实验组II（正常胚胎在含乙醇的培养基中培养）,各期植入前胚胎DNA甲基化水平均明显低于体外对照组。体内实验发现,体内实验组I（怀孕前酒精处理组）与体内的实验组II（怀孕后酒精处理组）,各期植入前胚胎DNA甲基化水平明显低于体内对照组。体内、外实验结果表明：受精前后酒精对各期植入前胚胎DNA甲基化模式的正确建立造成紊乱,该结果可为进一步揭示FSAD发病机制提供一定的实验基础。     

中国龙葵复合种细胞学分析和地理分布的研究

本文根据１５省３０余个县的实地考察,和对采自２５省的６６份中国龙葵种籽进行种植观察,并与国外的有关研究资料对比分析,在国内首次提出;（１）中国龙葵复合种的四个种,从低纬度到高纬度（１８．６－５３．５°Ｎ）,分别属于二倍体,四倍体和六倍体种;（２）从中国南方到北方,自然形成了二倍体,六倍体与二倍体交叉,六倍体与四倍体交叉三个地理分布区。     

ITE and TCDD Differentially Regulate the Vascular Remodeling of Rat Placenta via the Activation of AhR

Vascular remodeling in the placenta is essential for normal fetal development. The previous studies have demonstrated that in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an environmental toxicant) induces the intrauterine fetal death in many species via the activation of aryl hydrocarbon receptor (AhR). In the current study, we compared the effects of 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) and TCDD on the vascular remodeling of rat placentas. Pregnant rats on gestational day (GD) 15 were randomly assigned into 5 groups, and were exposed to a single dose of 1.6 and 8.0 mg/kg body weight (bw) ITE, 1.6 and 8.0 µg/kg bw TCDD, or an equivalent volume of the vehicle, respectively. The dams were sacrificed on GD20 and the placental tissues were gathered. The intrauterine fetal death was observed only in 8.0 µg/kg bw TCDD-exposed group and no significant difference was seen in either the placental weight or the fetal weight among all these groups. The immunohistochemical and histological analyses revealed that as compared with the vehicle-control, TCDD, but not ITE, suppressed the placental vascular remodeling, including reduced the ratio of the placental labyrinth zone to the basal zone thickness (at least 0.71 fold of control), inhibited the maternal sinusoids dilation and thickened the trophoblastic septa. However, no marked difference was observed in the density of fetal capillaries in the labyrinth zone among these groups, although significant differences were detected in the expression of angiogenic growth factors between ITE and TCDD-exposed groups, especially Angiopoietin-2 (Ang-2), Endoglin, Interferon-γ (IFN-γ) and placenta growth factor (PIGF). These results suggest ITE and TCDD differentially regulate the vascular remodeling of rat placentas, as well as the expression of angiogenic factors and their receptors, which in turn may alter the blood flow in the late gestation and partially resulted in intrauterine fetal death.