几个生态因子对黄盖鲽的影响

黄盖鲽(Psuedopleuronectes yokohameGünther)是鲽科中的冷温性鱼类,广泛分布在日本、朝鲜及我国的东海、黄海和渤海。地方种群多,洄游范尉小,适应能力强,既是底栖生物食性,又可耐较低的温度,虽非名贵鱼种,却具有一定的经济价值,在开展近海增殖时,不存在越冬和效益外流问题。因此,早在60年代,日本山口县和大分县的学者们,便开始着手该品种的人工孵化和增殖放流试验。80年代初已达年放流2—3cm的稚鱼苗7.0×10~6尾的水平。为了在渤海开展增殖工作,建立综     

Epstein─Barr病毒膜抗原在中国仓鼠卵巢（CHO）细胞中的表达

将切去３’端穿膜序列的ＥＢ病毒膜抗原（ＭＡ）基因,插入ｐＳＶ２－ｄｈｆｒ质粒的ＳＶ４０早期启动子下游,构建了真核表达载体ｐＳＶ２－ｄｈｆｒＧＰＴＲ,使两个ＳＶ４０早期启动子分别调控ＭＡ和二氢叶酸还原酶（ｄｈｆｒ）基因。将该重组质粒转化ＣＨＯ－ｄｈｆｒ细胞,在选择培养基中筛选阳性克隆,用氨甲喋呤加压扩增,建立了表达ＥＢＶ－ＭＡ的克隆细胞系。ｗｅｓｔｅｒｎｂｌｏｔ分析证明,所表达的蛋白的分子量大约为３４０ｋｄ和２２０ｋｄ。经过细Ｓｅｐｈａｒｏｓｅ２Ｂ琼脂糖凝胶层析初步纯化的抗原与福氏佐剂混合免疫小鼠,２周后小鼠血清中出现明显的ｇｐ３４０／２２０特异性抗体,表明切去嵌膜区结构的ＥＢＶ－ＭＡ基因在ＣＨＯ细胞中的表达产物具有同天然膜抗原相似的分子量大小、糖基化程度、免疫特异性和免疫原性,可望成为ＥＢ病毒人用基因工程亚单位疫苗。     

热带林下人工种植阳春砂仁的生长与果实产量动态

调查了西双版纳不同海拔热带沟谷雨林和次生林下的阳春砂仁生长和果实产量动态．结果表明,西双版纳热带林下阳春砂仁自身年龄增长、林下光照不足和旱季水分胁迫影响阳春砂仁果实产量。随种植期增加,阳春砂仁果实产量和成熟植株密度降低．当林下光照水平在全日照的35％以下时,阳春砂仁果实产量随林下日照水平变化呈线性增加(P<0．05)。沟谷下方阳春砂仁果实产量显著高于上方(P<0.05)。海拔600～1000m,由于阳春砂仁的主花期从干热季3～4月推迟到雨季5月,果实产量显著增加,沟谷雨林和次生林下阳春砂仁果实产量差异不显著。因此,在海拔800～1000m沟谷中轮歇地次生林下有计划种植阳春砂仁,代替在沟谷雨林下种植阳春砂仁,既能解决沟谷雨林下光照和当地旱季水分不足对阳春砂仁果实产量的影响,又有利于热带沟谷雨林的保护。     

Synaptic neurotransmission depression in ventral tegmental dopamine neurons and cannabinoid-associated addictive learning

Drug addiction is an association of compulsive drug use with long-term associative learning/memory. Multiple forms of learning/memory are primarily subserved by activity- or experience-dependent synaptic long-term potentiation (LTP) and long-term depression (LTD). Recent studies suggest LTP expression in locally activated glutamate synapses onto dopamine neurons (local Glu-DA synapses) of the midbrain ventral tegmental area (VTA) following a single or chronic exposure to many drugs of abuse, whereas a single exposure to cannabinoid did not significantly affect synaptic plasticity at these synapses. It is unknown whether chronic exposure of cannabis (marijuana or cannabinoids), the most commonly used illicit drug worldwide, induce LTP or LTD at these synapses. More importantly, whether such alterations in VTA synaptic plasticity causatively contribute to drug addictive behavior has not previously been addressed. Here we show in rats that chronic cannabinoid exposure activates VTA cannabinoid CB1 receptors to induce transient neurotransmission depression at VTA local Glu-DA synapses through activation of NMDA receptors and subsequent endocytosis of AMPA receptor GluR2 subunits. A GluR2-derived peptide blocks cannabinoid-induced VTA synaptic depression and conditioned place preference, i.e., learning to associate drug exposure with environmental cues. These data not only provide the first evidence, to our knowledge, that NMDA receptor-dependent synaptic depression at VTA dopamine circuitry requires GluR2 endocytosis, but also suggest an essential contribution of such synaptic depression to cannabinoid-associated addictive learning, in addition to pointing to novel pharmacological strategies for the treatment of cannabis addiction.     

MST1 promotes apoptosis through phosphorylation of histone H2AX

MST1 (mammalian STE20-like kinase 1) is a serine/threonine kinase that is cleaved and activated by caspases during apoptosis. Overexpression of MST1 induces apoptotic morphological changes such as chromatin condensation, but the mechanism is not clear. Here we show that MST1 induces apoptotic chromatin condensation through its phosphorylation of histone H2AX at Ser-139. During etoposide-induced apoptosis in Jurkat cells, the cleavage of MST1 directly corresponded with strong H2AX phosphorylation. In vitro kinase assay results showed that MST1 strongly phosphorylates histone H2AX. Western blot and kinase assay results with a mutant S139A H2AX confirmed that MST1 phosphorylates H2AX at Ser-139. Direct binding of MST1 and H2AX can be detected when co-expressed in HEK293 cells and was also confirmed by an endogenous immunoprecipitation study. When overexpressed in HeLa cells, both the MST1 full-length protein and the MST1 kinase domain (MST1-NT), but not the kinase-negative mutant (MST1-NT-KN), could induce obvious endogenous histone H2AX phosphorylation. The caspase-3 inhibitor benzyloxycarbonyl-DEVD-fluoromethyl ketone (Z-DEVD-fmk) attenuates phosphorylation of H2AX by MST1 but cannot inhibit MST1-NT-induced histone H2AX phosphorylation, indicating that cleaved MST1 is responsible for H2AX phosphorylation during apoptosis. Histone H2AX phosphorylation and DNA fragmentation were suppressed in MST1 knockdown Jurkat cells after etoposide treatment. Taken together, our data indicated that H2AX is a substrate of MST1, which functions to induce apoptotic chromatin condensation and DNA fragmentation.     

Ricin A chain reaches the endoplasmic reticulum after endocytosis

Ricin is a potent ribosome inactivating protein and now has been widely used for synthesis of immunotoxins. To target ribosome in the mammalian cytosol, ricin must firstly retrograde transport from the endomembrane system to reach the endoplasmic reticulum (ER) where the ricin A chain (RTA) is recognized by ER components that facilitate its membrane translocation to the cytosol. In the study, the fusion gene of enhanced green fluorescent protein (EGFP)-RTA was expressed with the pET-28a (+) system in Escherichia coli under the control of a T7 promoter. The fusion protein showed a green fluorescence. The recombinant protein can be purified by metal chelated affinity chromatography on a column of NTA. The rabbit anti-GFP antibody can recognize the fusion protein of EGFP-RTA just like the EGFP protein. The cytotoxicity of EGFP-RTA and RTA was evaluated by the MTT assay in HeLa and HEP-G2 cells following fluid-phase endocytosis. The fusion protein had a similar cytotoxicity of RTA. After endocytosis, the subcellular location of the fusion protein can be observed with the laser scanning confocal microscopy and the immuno-gold labeling Electro Microscopy. This study provided important evidence by a visualized way to prove that RTA does reach the endoplasmic reticulum.     

CDK5-Mediated Phosphorylation-Dependent Ubiquitination and Degradation of E3 Ubiquitin Ligases GP78 Accelerates Neuronal Death in Parkinson’s Disease

The molecular mechanisms responsible for the loss of dopaminergic neurons in Parkinson’s disease (PD) remain obscure. Loss of function of E3 ubiquitin ligases is associated with mitochondria dysfunction, dysfunction of protein degradation, and α-synuclein aggregation, which are major contributors to neurodegeneration in PD. Recent research has thus focused on E3 ubiquitin ligase glycoprotein 78 (GP78); however, the role of GP78 in PD pathogenesis remains unclear. Notably, cyclin-dependent kinase 5 (CDK5) controls multiple cellular events in postmitotic neurons, and CDK5 activity has been implicated in the pathogenesis of PD. Thus, we addressed the relationship between CDK5 and GP78 in MPTP-based PD models. We found that GP78 expression is decreased in MPTP-based cellular and animal PD models, and CDK5 directly phosphorylated GP78 at Ser516, which promoted the ubiquitination and degradation of GP78. Importantly, overexpression of GP78 or interference of GP78 Ser516 phosphorylation protected neurons against MPP⁺-induced cell death. Thus, our research reveals that the CDK5-GP78 pathway is involved in the pathogenesis of PD and could be a novel candidate drug target for the treatment of PD.     

广西大瑶山地区蚱科的新种（直翅目：蚱总科）

本记述采自广西大瑶山地区蚱科昆虫三新种,即拟仿蚱Tetriz simulanoides sp．nov、广西蚱Tetrix guangxiensis sp．nov及短背真长背蚱Euparutetzix brachynotus sp.nov。