Power and phase properties of oscillatory neural responses in the presence of background activity

Natural sensory inputs, such as speech and music, are often rhythmic. Recent studies have consistently demonstrated that these rhythmic stimuli cause the phase of oscillatory, i.e. rhythmic, neural activity, recorded as local field potential (LFP), electroencephalography (EEG) or magnetoencephalography (MEG), to synchronize with the stimulus. This phase synchronization, when not accompanied by any increase of response power, has been hypothesized to be the result of phase resetting of ongoing, spontaneous, neural oscillations measurable by LFP, EEG, or MEG. In this article, however, we argue that this same phenomenon can be easily explained without any phase resetting, and where the stimulus-synchronized activity is generated independently of background neural oscillations. It is demonstrated with a simple (but general) stochastic model that, purely due to statistical properties, phase synchronization, as measured by ‘inter-trial phase coherence’, is much more sensitive to stimulus-synchronized neural activity than is power. These results question the usefulness of analyzing the power and phase of stimulus-synchronized activity as separate and complementary measures; particularly in the case of attempting to demonstrate whether stimulus-synchronized neural activity is generated by phase resetting of ongoing neural oscillations.     

Efficient Protein Expression in <Emphasis Type="Italic">Bombyx mori</Emphasis> Larvae of the Strain d17 Highly Sensitive to <Emphasis Type="Italic">B. mori</Emphasis> Nucleopolyhedrovirus

The recombinant protein expression by Bombyx mori nucleopolyhedrovirus (BmNPV) infecting silkworm larvae or pupae may endow us with a potent system for the production of large eukaryotic proteins. However, the screening of silkworm strains ideally suited to this method has scarcely been conducted. In the present study, we injected recombinant BmNPV containing a reporter gene, luciferase or DsRed, into hemocoel of fifth instar larvae of selected 12 silkworm strains. Among them, the strain d17 is found to be the highest in reporter expression from the intrinsic polyhedrin promoter of Autographa californica NPV or the silkworm actin A3 promoter. These results suggest that the d17 strain is highly permissive for BmNPV replication and is the most likely candidate of a “factory” for large-scale expression using the BmNPV bacmid system.     

The serine protease matriptase-2 (TMPRSS6) inhibits hepcidin activation by cleaving membrane hemojuvelin

The liver peptide hepcidin regulates body iron, is upregulated in iron overload and inflammation, and is downregulated in iron deficiency/hypoxia. The transmembrane serine protease matriptase-2 (TMPRSS6) inhibits the hepcidin response and its mutational inactivation causes iron-deficient anemia in mice and humans. Here we confirm the inhibitory effect of matriptase-2 on hepcidin promoter; we show that matriptase-2 lacking the serine protease domain, identified in the anemic Mask mouse (matriptase-2(MASK)), is fully inactive and that mutant R774C found in patients with genetic iron deficiency has decreased inhibitory activity. Matriptase-2 cleaves hemojuvelin (HJV), a regulator of hepcidin, on plasma membrane; matriptase-2(MASK) shows no cleavage activity and the human mutant only partial cleavage capacity. Matriptase-2 interacts with HJV through the ectodomain since the interaction is conserved in matriptase-2(MASK). The expression of matriptase-2 mutants in zebrafish results in anemia, confirming the matriptase-2 role in iron metabolism and its interaction with HJV.     

中华绒螯蟹卵巢差减cDNA文库的构建

应用抑制性差减杂交技术构建中华绒螯蟹卵巢两个发育时期的差减cDNA文库。正向差减杂交以Ⅲ期卵巢为试验方、Ⅱ期卵巢为驱动方,反向差减杂交以Ⅱ期卵巢为试验方、Ⅲ期卵巢为驱动方;将所获差减cDNA片段克隆入质粒表达载体,转化大肠杆菌JM109。最后获得的正、反向差减文库分别含863、360个重组子。PCR扩增鉴定正、反向差减cDNA文库的插入片段平均大小分别为360和160bp,表明所构建的差减言语库适合进一步研究中华绒螯蟹卵巢发育相关基因。     

葡萄叶绿体rbcL基因的结构分析

以玫瑰香葡萄（Ｖｉｔｉｓｖｉｎｉｆｅｒａ Ｌ．）为材料,克隆了含有叶绿体ｒｂｃ Ｌ基因的３．１ ｋｂ Ｂａｍ ＨⅠ片段,构建了该基因的限制性酶切图谱,测定了该基因的核苷酸序列。所测的核苷酸序列总长度为２００４ ｂｐ,其中基因的编码区为１４２８ ｂｐ,编码一个含４７５ 个氨基酸的蛋白质,其分子量约为５３ ｋＤ;测定基因的５上游含启动子的部分共３５８ ｂｐ,包括－ １０ 区（ＴＡＡＡＡＴ）、－ ３５区（ＴＴＧＣＧＣ）和ＳＤ 序列（ＧＧＡＧＧ）;基因的３下游区共２１８ ｂｐ,含有３ 个转录茎环终止结构。玫瑰香葡萄ｒｂｃ Ｌ基因编码区的核苷酸序列与烟草、矮牵牛、菠菜、苜蓿、水稻和玉米之间的同源性分别为９１．５％ 、９１．４％ 、９０．２％ 、８９．８％ 、８６．３％ 和８４．５％ ;推导出的氨基酸序列的同源性分别为９２．２％ 、９１．６％ 、９２．２％ 、９３．７％ 、９３．５％ 和９０．１％ 。     

EM复合菌对新疆色素辣椒生长及根际细菌群落的影响

【背景】Effective microorganisms （EM）复合菌在我国农业种植上的应用越来越广泛,但对色素辣椒的促生作用与根际细菌群落结构的影响未见报道。【目的】评估EM复合菌对新疆色素辣椒的促生长作用,并分析其对色素辣椒根际细菌群落组成的影响。【方法】通过随水灌溉方式将EM复合菌接种到色素辣椒根部,在收获期测定辣椒生长指标、土壤养分和酶活活性,明确EM复合菌对辣椒生长和土壤质量的影响;利用16S rRNA基因高通量测序技术测定EM复合菌对辣椒根系细菌群落组成和结构的影响。【结果】与对照组相比,EM复合菌的施用使辣椒株高、鲜重、单个果重和单株结果数分别提高23.89%、85.41%、42.31%和46.04%;土壤中碱解氮和速效磷含量分别提高5.83%和13.39%,土壤中脲酶、蔗糖酶和过氧化物酶的活性分别提高11.47%、9.42%和21.43%;施用EM复合菌显著改变辣椒根际微生物群落的α多样性和β多样性,提高有益菌群变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、芽单胞菌门（Gemmatimonadetes）、放线菌门（Actinobacteria）和厚壁菌门（Firmicutes）的相对丰度,其中变形菌门黄单胞菌科（Xanthomonadaceae）的相对丰度增加119.32%;在属的水平上,施用EM复合菌显著增加了藤黄色杆菌属（Luteitalea）、藤黄单胞菌属（Luteimonas）、鞘脂单胞菌属（Sphingobacterium）和盐单胞菌属（Halomonas）的相对丰度,尤其是藤黄单胞菌属的丰度提高244.17%,同时显著降低黄杆菌属（Flavobacterium）的相对丰度。此外,与土壤理化指标呈正相关的微生物菌群相对丰度也显著升高。【结论】EM复合菌能够通过提高土壤营养成分与酶活活性,调控根系微生物群落结构,富集大量在盐碱地生存能力较强的有益菌群,进而起到促进色素辣椒生长的功效。     

Expression,Purification, and Characterization of Recombinant Human α<Subscript>1</Subscript>-Antitrypsin Produced Using Silkworm–Baculovirus Expression System

Human α₁-antitrypsin (AAT) is the most abundant serine proteinase inhibitor (serpin) in the human plasma. Commercially available AAT for the medications of deficiency of α₁-antitrypsin is mainly purified from human plasma. There is a high demand for a stable and low-cost supply of recombinant AAT (rAAT). In this study, the baculovirus expression vector system using silkworm larvae as host was employed and a large amount of highly active AAT was recovered from the silkworm serum (~?15 mg/10 ml) with high purity. Both the enzymatic activity and stability of purified rAAT were comparable with those of commercial product. Our results provide an alternative method for mass production of the active rAAT in pharmaceutical use.     

Effects of extracellular calcium on electrical bursting and intracellular and luminal calcium oscillations in insulin secreting pancreatic beta-cells.

The extracellular calcium concentration has interesting effects on bursting of pancreatic beta-cells. The mechanism underlying the extracellular Ca2+ effect is not well understood. By incorporating a low-threshold transient inward current to the store-operated bursting model of Chay, this paper elucidates the role of the extracellular Ca2+ concentration in influencing electrical activity, intracellular Ca2+ concentration, and the luminal Ca2+ concentration in the intracellular Ca2+ store. The possibility that this inward current is a carbachol-sensitive and TTX-insensitive Na+ current discovered by others is discussed. In addition, this paper explains how these three variables respond when various pharmacological agents are applied to the store-operated model.