Survey of numerical techniques for grouping

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Cell type-dependent collagen-type recognition by cell receptors.

Affinity chromatography of a number of cell types on collagens I and III reveals three proteins with M(R)of 250, 170 and 140 kDa. These proteins are able to discriminate between types I and III, but not types III and IV. Collagen-type recognition is therefore characteristic for cells of connective tissue origin. Polyclonal antibodies (Ab) raised against 170 and 140 kDa polypeptides and used in immunofluorescence show membrane localisation for both, with their distribution being similar to each other and to the distribution of the integrin beta1 chain. Ab p140 and commercial monoclonal antibodies against alpha(2)chain stain a band of the same molecular mass as from purified collagen binding proteins from liver cells, indicating that the 140 kDa protein is probably the alpha(2)integrin chain. The alpha(2)chain containing integrins are therefore able to discriminate collagen types I and III and collagen type recognition by this receptor is cell-type dependent.     

Cell surface molecules involved in NK recognition by cloned cytotoxic T lymphocytes

Short-term treatment of cloned mouse cytotoxic T lymphocytes (CTL) with interferon (IFN) induces lytic activity for natural killer- (NK) sensitive targets. Extended culture of CTL in high concentrations of interleukin 2 induces promiscuous lytic activity in which state both NK-sensitive and NK-resistant target cells are lysed. Cold-target competition analysis showed that the development of NK activity was associated with the acquisition of binding activity for NK-sensitive but not for NK-resistant targets, whereas the development of promiscuous lytic activity was associated with the acquisition of binding activity for both types of target. Antigen-specific cytolysis was inhibited by antibodies to Ly-2, Ly-5, LFA-1 and to the V region of the T cell antigen receptor (TCR), whereas NK and promiscuous lytic activity in the same cells was resistant to inhibition by anti-Ly-2 and anti-TCR. NK activity was expressed normally against a variant NK-sensitive cell line lacking all MHC antigens. These results show that, in contrast to antigen-specific recognition, the NK and promiscuous lytic activities of CTL are expressed without participation of effector cell Ly-2 and TCR molecules or target cell MHC molecules, and are most likely mediated through novel and distinct receptor systems.     

Cell adhesion molecules in context: CAM function depends on the neighborhood

Cell adhesion molecules (CAMs) are now known to mediate much more than adhesion between cells and between cells and the extracellular matrix. Work by many researchers has illuminated their roles in modulating activation of molecules such as receptor tyrosine kinases, with subsequent effects on cell survival, migration and process extension. CAMs are also known to serve as substrates for proteases that can create diffusible fragments capable of signaling independently from the CAM. The diversity of interactions is further modulated by membrane rafts, which can co-localize or separate potential signaling partners to affect the likelihood of a given signaling pathway being activated. Given the ever-growing number of known CAMs and the fact that their heterophilic binding in cis or in trans can affect their interactions with other molecules, including membrane-bound receptors, one would predict a wide range of effects attributable to a particular CAM in a particular cell at a particular stage of development. The function(s) of a given CAM must therefore be considered in the context of the history of the cell expressing it and the repertoire of molecules expressed both by that cell and its neighbors.Key words: cell adhesion molecule, fibroblast growth factor receptor, epidermal growth factor receptor, L1, NCAM, Neuroglian, fasciclin, membrane raft, ankyrin, doublecortin, ezrin, radixin, moesinCell migration, axon extension and dendrite arborization are all essential processes in creating the complex neural architectures of the developing brain. A number of CAMs, including those of the immunoglobulin superfamily (IgCAMs), integrins and cadherins, are known to mediate signaling between cells and between cells and the extracellular matrix (ECM). Because the greatest amount of IgCAM research has focused on L1-CAM and NCAM and their invertebrate homologs Neuroglian and Fasciclin II, these molecules will be the primary focus of this Commentary & View. IgCAMs are so named because their extracellular domains contain immunoglobulin repeats (usually 5–6). The Ig repeats are usually followed by fibronectin type-3 (Fn III) domains (2–5) and either transmembrane plus cytoplasmic domains or a glycosyl-phosphatidylinositol (GPI) linkage (reviewed in refs. ^1–3). IgCAMs can bind homophilically and heterophilically via their Ig and/or Fn III domains to achieve cell-cell and cell-ECM adhesion, which can simply stabilize the architecture of neural tissue, but can also transmit information to the cell interior.⁴ For example, a number of IgCAMs are known to bind to the cytoskeleton via linker molecules including Ankyrin, Doublecortin and members of the Ezrin-Radixin-Moesin family (ERMs).^5–12 Some of these linking interactions are thought to allow engagement or disengagement of a molecular “clutch module” (reviewed in ref. ¹³) similar to coupling of integrins to F-actin flow via focal adhesion proteins and are believed to be important in growth cone function and synaptogenesis.^14,15 Work from these groups suggests these linker molecules are expressed in different developmental windows, so that ERMs and Doublecortin are important in L1-mediated neurite outgrowth and suppression of neurite branching, while subsequent Ankyrin expression and binding to L1 blocks outgrowth and fosters axon stabilization and synaptogenesis.^6–12 Another important example of outside-in signaling by IgCAMs is their ability, via Ankyrin''s multivalent binding sites, to cluster and position many receptors and channels at specific cellular locations such as axon initial segments and nodes of Ranvier (reviewed in ref. ¹² and ¹⁶). IgCAMs have also been shown to be substrates for matrix metalloproteases (MMPs), which can cleave extracellular domains, allowing the fragments to act as diffusable signaling molecules and changing the signaling effects of the remaining membrane-bound moieties.^17,18     

Detection of abnormal fermentations in wine process by multivariate statistics and pattern recognition techniques

Three multivariate statistical techniques (Multiway Principal Component Analysis, Multiway Partial Least Squares, and Stepwise Linear Discriminant Analysis) and one artificial intelligence method (Artificial Neural Networks) were evaluated to detect and predict early abnormal behaviors of wine fermentations. The techniques were tested with data of thirty-two variables at different stages of fermentation from industrial wine fermentations of Cabernet Sauvignon. All the techniques studied considered a pre-treatment to obtain a homogeneous space and reduce the overfitting. The results were encouraging; it was possible to classify at 72h 100% of the fermentation correctly with three variables using Multiway Partial Least Squares and Artificial Neural Networks. Additional and complementary results were obtained with Stepwise Linear Discriminant Analysis, which found that ethanol, sugars and density measurements are able to discriminate abnormal behavior.     

Effect of focus on cell detection and recognition by the Cell Analyzer

The effect of defocusing on the quality of signals from live cells detected by an automated image cytometry device, the Cell Analyzer, was examined. The influence of these effects on the ability of this device to automatically locate cells plated into a tissue culture flask was then determined by measuring the performance of cell detection and recognition procedures as a function of focus setting. Acceptable limits for deviation from the optimal focus setting (as determined by microscope objective position) were found to be similar for both these procedures, ranging from 40 microns below to 25 microns above the optimal focus position. These limits were asymmetrical about ideal focus due to a pronounced asymmetry in the effects of positive and negative defocusing on the cell signal.     

面向鸟鸣声识别任务的深度学习技术

在生态系统中,鸟类是重要的组成部分,对调节生态环境和监测生物多样性至关重要,甚至可以通过监测鸟群动向与监听鸟群异常鸣声对地震、海啸等自然灾害进行辅助预测和防范,为此,鸟鸣声识别和异常鸣声监测成为热门的研究方向。然而,由于传统鸟鸣声识别方法存在特征提取不充分等问题,导致识别率不高。本文采用融合特征的方法结合深度学习技术提取鸟鸣声特征,融合特征选择改良后的对数梅尔谱差分参数同原始信号参数拼接所得的特征;深度学习方法是基于Dense Net121网络结构,并融入自注意力模块与中心损失函数进行鸟鸣声识别。自注意力模块部分提高了关键通道的特征表达能力;中心损失函数可解决类内特征不紧凑问题。我们通过消融实验对比验证,对在Xeno-Canto世界野生鸟类声音公开数据集上选取的10种鸟类声音进行识别,准确率达到96.9%。代码已开源至Github:https://github.com/Carrie X6/-Xeno-Canto-.git。     

Application of learning techniques to splicing site recognition

Most genes of eukaryotic genomes are disrupted by introns. The application of a learning technique which uses both statistic and syntactic analysis lead to the establishment of logical rules enabling the recognition of intron/exon junctions between uncoding and coding sequences. The rules were tested on rat actin gene sequences containing some or all of the introns and 50 exon nucleotides on either side of the intron. The results show good recognition of the excision site. This recognition is more ambiguous when the sequence is short; for the acceptor sequence it presents a good selection. The learning achieved with both the donor and acceptor sequence does not lead to recognition. This result indicates that it is not the relationship between donor and acceptor sites in the same intron which determines sequence selection or the splicing mechanism.     

Cell recognition among blood leukocytes: A new theory for cell recognition

Summary Blood leukocytes exhibit specific cell type recognition. Neutrophils adhere to neutrophils, eosinophils to eosinophils, basophils to basophils and monocytes to monocytes. Rather large homotypic aggragates are formed. These are almost abolished by prior treatment of the cells with trypsin. It is assumed that a protein is involved in this type of cell recognition. protein monomer-monomer interaction could provide the specificity required in homotypic aggregate formation.     

Cell culture-based biosensing techniques for detecting toxicity in water

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Cell culture techniques for studying insect cuticle

Evidence that biosynthetic pathways critical to the formation of insect cuticle are retained in continuous insect cell lines opens new possibilities for research on the cuticle system. Recent findings indicate that chitin, molting hormone, and catecholamines are all produced by a vesicle cell line derived from embryos of the cockroach Blattella germanica. The chitin that is formed by this cell line is particulate and does not show the characteristic featherlike crystalline structure found in mature cuticle. The molting hormone is produced as ecdysone and is released into the culture medium. The addition of 20-hydroxyecdysone to the cultures increases the production of chitin fourfold. These responses are similar to those found in insect organ cultures.