Engineering novel Lec1 glycosylation mutants in CHO-DUKX cells: molecular insights and effector modulation of N-acetylglucosaminyltransferase I

Many secreted or cell surface proteins are post-translationally modified by carbohydrate chains which are a primary source of heterogeneity. The Lec1 mutant, which is defective in Golgi N-acetylglucosaminyltransferase I (GnTI) activity, produces relatively homogeneous Man(5) GlcNAc(2) glycan modifications, and is widely used for various applications. To facilitate the investigation of GnTI, its Man5 glycan endproduct, and the impact of Man5 on effector function, the present study has established several novel Lec1 mutants in dhfr(-) CHO-DUKX cells through chemical mutagenesis and lectin selection. A total of nine clonal lines exhibiting the Lec1-phenotype are characterized, six of which harbor non-sense mutations leading to a truncated GnTI, and three (R415K, D291N, and P138L) of which are novel loss-of-function sense mutations. Analysis of the rabbit GnTI structure (Unligil et al., 2000) indicates that D291 is the proposed catalytic base and R415 is a crucial residue in forming the substrate binding pocket, whereas P138 is key to maintaining two β strands in proximity to the substrate binding pocket. Computational modeling reveals that the oligomannose glycan backbone of a glycoprotein (the acceptor substrate) fits nicely into the unoccupied channel of the substrate binding pocket partly through hydrogen bonding with R415 and D291. This finding is consistent with the ordered sequential Bi Bi kinetic mechanism suggested for GnTI, in which binding of UDP-GlcNAc (the donor substrate)/Mn(2+) induces conformational changes that promote acceptor binding. When an anti-human CD20 antibody protein is stably expressed in one CHO-DUKX-Lec1 line, it is confirmed that N-glycans are predominantly Man(5) GlcNAc(2) and they do not contain an α1,6-fucose linked to the innermost GlcNAc. Furthermore, this Man(5) GlcNAc(2) modified antibody exhibits a significantly increased ADCC activity than the wild-type protein, while displaying a lower CDC activity. The data support the hypothesis that modulating GnTI activity can influence antibody effector functions for proteins with an IgG1 immunoglobulin Fc domain.     

肠道味觉受体细胞及其甜味感受

味觉是人和动物的一种基本生理感觉,用来识别食物的性质、调节食欲、控制摄食量.味觉不仅仅存在于口腔中,同样存在于胃肠道中.最近研究表明,动物肠道的粘膜上存在着表达味觉受体和味觉相关因子的细胞,调控着肠道激素如GLP-1和GIP的分泌以及糖转运体SGLT-1和GLUT-2的表达.甜味剂的刺激影响这些激素的分泌及载体的表达,从而影响机体对葡萄糖的吸收和利用.肠道味觉的研究有助于揭示肠道消化吸收功能的调控机理,同时为糖尿病、肥胖、代谢失调及其它饮食相关疾病的治疗提供新的切入点.主要介绍了肠道粘膜上的味觉受体细胞、味觉的信号转导途径以及甜味感受对肠道激素的分泌和葡萄糖吸收的影响,最后讨论了味觉细胞生物学的发展方向.     

On the role of emotion in biological and robotic autonomy

This paper reviews some of the differences between notions of biological and robotic autonomy, and how these differences have been reflected in discussions of embodiment, grounding and other concepts in AI and autonomous robotics. Furthermore, the relations between homeostasis, emotion and embodied cognition are discussed as well as recent proposals to model their interplay in robots, which reflects a commitment to a multi-tiered affectively/emotionally embodied view of mind that takes organismic embodiment more serious than usually done in biologically inspired robotics.     

PH结构域与细胞方向感觉

PH（pleckstrin homology）结构域与细胞方向感觉关系密切,目前已发现,PH结构域存在于60多种蛋白质中,这些蛋白质能与趋化细胞胞膜表面的相关结合位点结合,进而激发信号转导的下游事件.这种结合有以下特点：a.迅速而短暂;b.只与外界环境中两点间浓度梯度差相关,据此提出了“空间模式”;c.改变趋化剂的位置时,结合位点在胞膜上的分布也随之改变,由此提出了“时间模式”.深入而全面地探讨各种PH结构域及其结合位点在细胞方向感觉中的作用,对于细胞方向感觉的研究具有巨大的推动作用和深远的理论意义.     

Imaging emotional brain functions: Conceptual and methodological issues

This article reviews the psychophysiological and brain imaging literature on emotional brain function from a methodological point of view. The difficulties in defining, operationalising and measuring emotional activation and, in particular, aversive learning will be considered. Emotion is a response of the organism during an episode of major significance and involves physiological activation, motivational, perceptual, evaluative and learning processes, motor expression, action tendencies and monitoring/subjective feelings. Despite the advances in assessing the physiological correlates of emotional perception and learning processes, a critical appraisal shows that functional neuroimaging approaches encounter methodological difficulties regarding measurement precision (e.g., response scaling and reproducibility) and validity (e.g., response specificity, generalisation to other paradigms, subjects or settings). Since emotional processes are not only the result of localised but also of widely distributed activation, a more representative model of assessment is needed that systematically relates the hierarchy of high- and low-level emotion constructs with the corresponding patterns of activity and functional connectivity of the brain.     

The electromagnetic basis of social interactions

It has been established that living things are sensitive to extremely low-frequency magnetic fields at vanishingly small intensities, on the order of tens of nT. We hypothesize, as a consequence of this sensitivity, that some fraction of an individual’s central nervous system activity can be magnetically detected by nearby individuals. Even if we restrict the information content of such processes to merely simple magnetic cues that are unconsciously received by individuals undergoing close-knit continuing exposure to these cues, it is likely that they will tend to associate these cues with the transmitting individual, no less than would occur if such signals were visual or auditory. Furthermore, following what happens when one experiences prolonged exposure to visual and like sensory inputs, it can be anticipated that such association occurring magnetically will eventually also enable the receiving individual to bond to the transmitting individual. One can readily extrapolate from single individuals to groups, finding reasonable explanations for group behavior in a number of social situations, including those occurring in families, animal packs, gatherings as found in concerts, movie theaters and sports arenas, riots and selected predatory/prey situations. The argument developed here not only is consistent with the notion of a magnetic sense in humans, but also provides a new approach to electromagnetic hypersensitivity, suggesting that it may simply result from sensory overload.     

Feeling your way in Java: An essay on society and emotion

This article reconsiders the place of emotion in society. With the example of Java, I argue for an expanded understanding of social sentiments that would recognize a structuring role for emotion beyond the family and the shaping, through emotional practices, of a fluid but crucial level of ‘community’. Using Balinese ethnology as a foil, I contrast the uses of emotion in Java and Bali, drawing, toward the end, upon Bateson's concept of schismogenesis.     

The sensory equipment of a spider – A morphological survey of different types of sensillum in both sexes of Argiope bruennichi (Araneae,Araneidae)

Spiders show a wide range of sensory capabilities as evidenced by behavioural observations. Accordingly, spiders possess diverse sensory structures like mechano-, hygro-, thermo- or chemoreceptive sensilla. As to chemoreceptive structures, only trichoid tip-pore sensilla were found so far that were tested for gustation. That spiders are also able to receive airborne signals is corroborated by numerous behavioural experiments but the responsible structures have not been determined yet. Here, we provide sensilla distribution maps of pedipalps and walking legs of both sexes of the wasp spider Argiope bruennichi whose biology and mating system is well explored. By means of scanning electron microscopy, we scrutinized whether there is in fact only one type of trichoid pore sensillum and if so, if there are deviations in the outer structure of the tip-pore sensilla depending on their position on the body. We also describe the external structure and distribution of slit sense organs, trichobothria and tarsal organs. Our study shows that all four sensillum types occur on pedipalps and walking legs of both sexes. As to chemosensory organs, only tip-pore sensilla were found, suggesting that this sensillum type is used for both gustation and olfaction. The highest numbers of tip-pore sensilla were observed on metatarsi and tarsi of the first two walking legs. Mechanosensitive slit sense organs occur as single slit sensilla in rows along all podomers or as lyriform organs next to the joints. The mechanosensitive trichobothria occur on the basal part of tibiae and metatarsi. Tarsal organs occur on the dorsal side of all tarsi and the male cymbium. The distribution maps of the sensilla are the starting point for further exploration of internal, morphological differences of the sensilla from different regions on the body. Cryptic anatomical differences might be linked to functional differences that can be explored in combination with electrophysiological analyses. Consequently, the maps will help to elucidate the sensory world of spiders.     

Low temperature perception in plants: effects of cold on protein phosphorylation in cell-free extracts

Activities of prevalent protein phosphatases decreased by nearly 95% and those of individual protein kinases were differentially reduced at low temperature. Inhibition of phosphatase activity at temperatures below 12°C resulted in marked hyperphosphorylation of a 58-kDa protein (PP58). The temperature threshold for hyperphosphorylation of PP58 coincided with the known threshold for cold-induced calcium influx. Since calcium influx is triggered by several environmental stresses, we propose that the observed direct effects of cold on the phosphorylation of specific proteins enable cells to couple a shared calcium signal to a cold-specific transduction pathway.     

马尾松毛虫灾害遥感监测模型的建立

本文在文献的基础上挑选出郁闭度≥0.5的密郁闭林分共307块,经过统计分析认为TM5/TM4与松毛虫灾有极为密切的关系,同时利用非参数的加权平均的方法建立了针叶损失率与TM5／TM4之间的非线性统计关系,并与其线性关系进行了比较,从而为区分各级松毛虫灾提供了有力的数值依据．遥感分析结果与地面调查结果基本一致。