Sweet-sensitive protein from bovine taste buds: isolation and assay

Using refractometry and ultraviolet-difference spectroscopy to indicate interaction between proteins and coinpounds of low molecular weight, we found a protein fraction in bovine tongue extracts that coinplexes sugars and saccharin. The strengths of the coinzplexes parallel the degrees of sweetness of the compounds, and the effects of pH upon formation of complexes parallel the effects of pH upon sensitivity of taste buds to sweet compounds in vivo.     

Entorhinal cortex layer III input to the hippocampus is crucial for temporal association memory

Associating temporally discontinuous elements is crucial for the formation of episodic and working memories that depend on the hippocampal-entorhinal network. However, the neural circuits subserving these associations have remained unknown. The layer III inputs of the entorhinal cortex to the hippocampus may contribute to this process. To test this hypothesis, we generated a transgenic mouse in which these inputs are specifically inhibited. The mutant mice displayed significant impairments in spatial working-memory tasks and in the encoding phase of trace fear-conditioning. These results indicate a critical role of the entorhinal cortex layer III inputs to the hippocampus in temporal association memory.     

Infectious disease. Research (genomics) is crucial to attacking malaria

Solving the enormous problem of malaria worldwide will require a balance between investments in research and control. In this point-counterpoint, two scientists describe the rationales for these very different strategies. Steve Hoffman believes that genomics research is the best investment in the future if we have the vision of malaria eradication. Chris Curtis presents an opposing viewpoint, that low-tech control approaches are the practical ones under current conditions.     

Transneuronal transfer of herpes virus from peripheral nerves to cortex and brainstem

The transneuronal transfer of neurotropic viruses may represent an effective tool for tracing chains of connected neurons because replication of virus in the recipient neurons after transfer amplifies the "tracer signal." Herpes simplex virus type 1 was transferred transneuronally from forelimb and hindlimb nerves of rats to the cortical and brainstem neurons that project to the spinal enlargements to which the nerves receiving injections are connected. This transneuronal transfer of herpes simplex virus type 1 from peripheral nerves has the potential to be used to identify neurons in the brain that are related transsynaptically to different nerves and muscles.     

Nuclear receptor-dependent bile acid signaling is required for normal liver regeneration

Liver mass depends on one or more unidentified humoral signals that drive regeneration when liver functional capacity is diminished. Bile acids are important liver products, and their levels are tightly regulated. Here, we identify a role for nuclear receptor-dependent bile acid signaling in normal liver regeneration. Elevated bile acid levels accelerate regeneration, and decreased levels inhibit liver regrowth, as does the absence of the primary nuclear bile acid receptor FXR. We propose that FXR activation by increased bile acid flux is a signal of decreased functional capacity of the liver. FXR, and possibly other nuclear receptors, may promote homeostasis not only by regulating expression of appropriate metabolic target genes but also by driving homeotrophic liver growth.     

Brassinosteroid signaling: a paradigm for steroid hormone signaling from the cell surface

Plants use the coordinated action of several small-molecule hormones to grow and develop optimally in response to a changing environment. Among these hormones are the brassinosteroids (BRs), the polyhydroxylated steroid hormones of plants. BRs bind a small family of leucine-rich repeat receptor kinases at the cell surface, thereby initiating an intracellular signal transduction cascade that results in the altered expression of hundreds of genes.     

The protein kinase domain of the ANP receptor is required for signaling

A plasma membrane form of guanylate cyclase is a cell surface receptor for atrial natriuretic peptide (ANP). In response to ANP binding, the receptor-enzyme produces increased amounts of the second messenger, guanosine 3',5'-monophosphate. Maximal activation of the cyclase requires the presence of adenosine 5'-triphosphate (ATP) or nonhydrolyzable ATP analogs. The intracellular region of the receptor contains at least two domains with homology to other proteins, one possessing sequence similarity to protein kinase catalytic domains, the other to regions of unknown function in a cytoplasmic form of guanylate cyclase and in adenylate cyclase. It is now shown that the protein kinase-like domain functions as a regulatory element and that the second domain possesses catalytic activity. When the kinase-like domain was removed by deletion mutagenesis, the resulting ANP receptor retained guanylate cyclase activity, but this activity was independent of ANP and its stimulation by ATP was markedly reduced. A model for signal transduction is suggested in which binding of ANP to the extracellular domain of its receptor initiates a conformational change in the protein kinase-like domain, resulting in derepression of guanylate cyclase activity.     

响应面法优化软糯口感的粉圆制作配方

【目的】优化粉圆配方工艺条件,为软糯口感粉圆的加工生产提供技术支持。【方法】以木薯淀粉为原料,以感官评分和质构参数为评价指标,在单因素试验基础上,利用Design-Expert 8.0.6进行响应面分析,并建立二次多项式数学模型,依据回归分析确定粉圆最优工艺条件。【结果】建立了感官评分（Y）对羧甲基纤维素钠添加量（A）、黄原胶添加量（B）和瓜尔豆胶添加量（C）的二次回归方程: Y=89.9-0.18A-0.79B-0.22C+0.36AB+0.92AC+2.06BC-1.78A2-2.14B2-1.03C2。各因素对粉圆感官评价的影响排序为黄原胶添加量>瓜尔豆胶添加量>羧甲基纤维素钠添加量;黄原胶添加量与瓜尔豆胶添加量的交互作用对粉圆感官品质影响极显著（P<0.01）,羧甲基纤维素钠添加量与瓜尔豆胶添加量的交互作用影响显著（P<0.05）。粉圆制作的最优配方为:预糊化淀粉添加量0.07%、羧甲基纤维素钠添加量0.08%、黄原胶添加量0.05%、瓜尔豆胶添加量0.05%,在此条件下,粉圆感官评分91.4分,与模型预测值（89.9分）接近,且弹性（0.671）、咀嚼性（426.5 gf）、硬度（807.2 gf）、粘结性（1644 gf·mm）和内聚性（0.788）等质构数据相对较好。【结论】通过响应面试验优化的粉圆制作配方可有效提高粉圆感官品质,表现出粉圆感官与质构特性的关系,建立的回归模型可靠,可为实际生产提供理论依据和预测。     

多子芋母芋不同芽位切块作种对后代生长的影响

多子芋母芋的顶芽和不同部位的腋芽在切块作种后 ,不同部位芽的发芽率、生长势、产量的构成性状分为 3个群体 ,3个群体的强弱趋势表现为 :第 1个群体 (顶芽 ) >第 3个群体 (第 6～ 9芽 ) >第2个群体 (第 2～ 5芽 )。所有性状的各处理间的差异均未达显著水平     

G protein signaling from activated rat frizzled-1 to the beta-catenin-Lef-Tcf pathway

The frizzled receptors, which mediate development and display seven hydrophobic, membrane-spanning segments, are cell membrane-localized. We constructed a chimeric receptor with the ligand-binding and transmembrane segments from the beta2-adrenergic receptor (beta2AR) and the cytoplasmic domains from rat Frizzled-1 (Rfz1). Stimulation of mouse F9 clones expressing the chimera (beta2AR-Rfz1) with the beta-adrenergic agonist isoproterenol stimulated stabilization of beta-catenin, activation of a beta-catenin-sensitive promoter, and formation of primitive endoderm. The response was blocked by inactivation of pertussis toxin-sensitive, heterotrimeric guanine nucleotide-binding proteins (G proteins) and by depletion of Galphaq and Galphao. Thus, G proteins are elements of Wnt/Frizzled-1 signaling to the beta-catenin-lymphoid-enhancer factor (LEF)-T cell factor (Tcf) pathway.     

辛夷挥发油含量及良种选育指标研究

对国产5种辛夷树种,即望春玉兰Y．biondii(Pamp．)D．L．Fu,腋花玉兰Y．axillfloram(T．B．Zhao et a1．)D．L．Fu罗田玉兰Y．pilocarpa(Z．Z．Zhao et Z．W．Xie)D．L.Fu,玉兰Y．denudata(Desr．)D．L.Fu和紫玉兰Y．liliiflora(Desr.)D.L.Fu的46个品种资源的挥发油含率、百蕾重和百蕾油量作了测定与分析．结果表明,辛夷5树种间数量性状差异显著,其中望春玉兰的挥发油含率和百蕾油量均显著高于总体平均值,望春玉兰挥发油含率最高可达7．2％．紫玉兰的挥发油含率、百蕾重和百蕾油量明显小于总体平均值,百蕾油量达到极显著差异．望春玉兰和玉兰辛夷数量性状的种内变异也很丰富,其中,望春玉兰挥发油含率种内变异系数为27．3％、百蕾油量的种内变异系数42．4％,均明显大于玉兰变异系数．依据46个辛夷品种的性状测定结果,提出辛夷良种选育指标为挥发油含率大于4．1％、百蕾重大于42．3g、百蕾油量大于1．61mL以上研究结果为辛夷的良种选育与推广、辛夷挥发油的开发利用奠定了科学基础．     

Machine-to-machine communication for agricultural systems: An XML-based auxiliary language to enhance semantic interoperability

This paper puts forth an Internet-based architecture for machine-to-machine communication and computation that enhances bio-productivity in agriculture. The approach utilizes an auxiliary language to enable data interoperability in a synthetic computing environment and to make connections between data and mathematical models. The approach also includes some aspects of cloud and context aware computing. At the prototype level, a practical application from the Florida citrus industry demonstrates the concept. In general, future agricultural systems will be Internet-based thus reducing cost and increasing capability. Standards organizations are certain to play an important role in this development, which might continue for the next decade or longer.     

加强培训是农民致富奔康的战略措施

农民的科学文化素质低下是农民致富奔康的最大障碍,解决之道就是加强培训之掌握新知识新技能。针对农民培训中存在的冷、散、僵的问题,要通过加强领导、政策支持、整合资源、丰富内容、搞活形式等措施加强对农民的培训工作。     

The cholinergic neuronal differentiation factor from heart cells is identical to leukemia inhibitory factor

A protein secreted by cultured rat heart cells can direct the choice of neurotransmitter phenotype made by cultured rat sympathetic neurons. Structural analysis and biological assays demonstrated that this protein is identical to a protein that regulates the growth and differentiation of embryonic stem cells and myeloid cells, and that stimulates bone remodeling and acute-phase protein synthesis in hepatocytes. This protein has been termed D factor, DIA, DIF, DRF, HSFIII, and LIF. Thus, this cytokine, like IL-6 and TGF beta, regulates growth and differentiation in the embryo and in the adult in many tissues, now including the nervous system.