Cell Polarity

The effect of 5-aminoimidazole-4-carboxamide-ribonucleoside (AICAR) activation of the AMP-activated protein kinase (AMPK) on the transport of the model radiolabeled dipeptide [3H]-D-Phe-L-Gln was investigated in the human epithelial colon cancer cell line Caco-2. Uptake and transepithelial fluxes of [3H]-D-Phe-L-Gln were carried out in differentiated Caco-2 cell monolayers, and hPepT1 and glucose transporter 2 (GLUT2) protein levels were quantified by immunogold electron microscopy. AICAR treatment of Caco-2 cells significantly inhibited apical [3H]-D-Phe-L-Gln uptake, matched by a decrease in brush-border membrane hPepT1 protein but with a concomitant increase in the facilitated glucose transporter GLUT2. A restructuring of the apical brush-border membrane was seen by electron microscopy. The hPepT1-mediated transepithelial (A-to-B) peptide flux across the Caco-2 monolayers showed no significant alteration in AICAR-treated cells. The electrical resistance in the AICAR-treated monol...

Connexins (Cx) comprise a family of transmembrane proteins, which form intercellular channels between plasma membranes of two adjoining cells, commonly known as gap junctions. Recent reports revealed that Cx proteins interact with diverse cellular components to form a multiprotein complex, which has been termed "Nexus". Potential interaction partners include proteins such as cytoskeletal proteins, scaffolding proteins, protein kinases and phosphatases. These interactions allow correct subcellular localization of Cxs and functional regulation of gap junction-mediated intercellular communication. Evidence is accruing that Cxs might have channel-independent functions, which potentially include regulation of cell migration, cell polarization and growth control. In the current review, we summarize recent knowledge on Cx interactions with cytoskeletal proteins and highlight some aspects of their role in cellular motility.

The flowering plant germline is produced during the haploid gametophytic stage. Defining the germline is complicated by the extreme reduction of the male and female gametophytes, also referred to as pollen and embryo sac, respectively. Both male and female gamete progenitors are segregated by an asymmetric cell division, as is the case for the germline in animals. Genetic studies and access to the transcriptome of isolated gametes have provided a regulatory framework for the mechanisms that define the male germline. What specifies female germline identity remains unknown. Recent evidence indicates that an auxin gradient provides positional information and plays a role in defining the identity of the female gamete lineage. The animal germline is also marked by production of small RNAs, and recent evidence indicates that this trait might be shared with the plant gamete lineage.

Various subpopulations of T lymphocytes—i.e. Type 1, Type 2, Tr1 T cells—play a major role in the homeostasis of the immune system and in the pathogenesis of many inflammatory and auto-immune diseases. At present, in the absence of specific surface markers, these T cells can only be reliably distinguished on the basis of their cytokine production profile. The Elispot assay detects cytokine-producing cells, but in most cases can detect only one secreted cytokine, which represents a major limitation of this technique.We have developed a Fluorospot assay to detect single cells that simultaneously produce multiple cytokines. The Fluorospot assay permits the detection of regulatory T cells with an immunosuppressive activity, identified by their coexpression of IL-10 and IFNγ. Polarized type 1 and type 2 specific tetanus toxoid T cells are also directly detected using a dual color Fluorospot. This technique will therefore be useful for detailed analysis of T lymphocytes in various disease states in which an imbalance of T cell subpopulations is suspected, but will also provide a better characterization of polarized specific immune responses.

The present paper deals with an outdoor environment of Laptop and Mobile Charging Station which provides a charging to the Laptop and Mobile with the help of Solar and Wind Energy &Vertical Windmill (power generators). The equipment has been developed based on the presentday scenario as the people usually run out of phone and laptop charging while travelling. At such times there is literally no way of charging your phone laptop in an outdoor environment, the solar and wind energy is used in order to collect the solar energy and convert it into the electrical energy and also the vertical windmill is used in order to observe the flow of wind and collect it. These two are intertwined together in the system, and the energy produced by both power generators is stored in a battery. This battery source is now available for use according to the inverter. The system provides 2 types of outputs. 4 USB outputs for charging for laptop and mobiles. The model is built in such a way that a common man can afford and this project model will lead a step ahead for economical utilization.

The Movie reviews and ratings are used by the people to decide which movie to buy or watch. Movie reviews are used as a recommendation, on whether it's worth spending time and money to watch or buy a movie. Reviews contain both positive and negative opinion on the movie. Ratings are calculated based on the total positive reviews of the movie. Therefore it is important to identify whether the given review is a positive or negative. In this paper we have used movie review dataset (aclimdb) to train our machine and logistic regression algorithm which is used to predict the polarity of a given movie review. Introduction Decision making place an important role in human life, a good and correct decision will make our life better. Decisions can made based on others opinions. Manual efforts on thinking and wasting time in taking decisions are decreased. In case of deciding on which movie to buy or watch, people look at websites, which provides reviews and ratings of the movies. This makes people to decide on which movie to buy or watch. People may have good or bad opinion about the movie, they express there opinion through reviews in the websites like amazon, BookMyShow etc. Where people look at the reviews and ratings to decide which movie to watch or buy. Good opinions about the movies are classified as positive and bad opinions are classified as negative. Review containing "good", "wonderful", "enjoyed" like keywords are called as positive. Review containing "not nice", "bad" like keywords are called as negative. Movie ratings are calculated based on the positive opinion about the movie. Sentiment analysis is a technique used to classify positive and negative opinion of the movie review. Where sentiment analysis is text classification tool, which analyses the text and identifies the polarity of the text.

A key goal of developmental biology is to understand the mechanisms that coordinate organ growth. It has long been recognized that the genes that control apico-basal cell polarity also regulate tissue growth. How loss of cell polarity contributes to tissue overgrowth has been the subject of much speculation. Do loss-of-function mutations in cell polarity regulators result in secondary effects that globally deregulate cell proliferation, or do these genes specifically control growth pathways? Three recent papers have shown that the apico-basal polarity determinants Lgl/aPKC and Crb regulate tissue growth independently of their roles in cell polarity and coordinately regulate cell proliferation and cell death via the Salvador/Warts/Hippo (SWH) pathway. Lgl/aPKC are required for the correct localization of Hippo (Hpo)/Ras associated factor (RASSF), while Crb regulates the levels and localization of Expanded (Ex), indicating that cell polarity determinants modify SWH pathway activity by distinct mechanisms. Here, we review the key data that support these conclusions, highlight remaining questions and speculate on the underlying mechanisms by which the cell polarity complexes interact with the SWH pathway. Understanding the interactions between cell polarity regulators and the SWH pathway will improve our knowledge of how epithelial organization and tissue growth are coordinated during development and perturbed in disease states such as cancer.

Les GTPases de la famille Ypt/Rab sont impliquées dans la régulation du trafic vésiculaire, et plus particulièrement dans les étapes de transport, d’arrimage et de fusion des vésicules. La régulation de leur activité GTPase est importante pour la régulation de leurs fonctions. L’activité GTPase des protéines Ypt/Rab est stimulée par des protéines activatrices de GTPase. Chez la levure Saccharomyces cerevisiae, il existe 10 protéines portant un domaine catalytique des protéines activatrices des GTPases Ypt/Rab. Gyp5p et Gyl1p sont deux protéines paralogues qui font partie de cette famille de protéines. In vitro, Gyp5p stimule l’activité GTPase de Ypt1p, qui est impliquée dans le transport entre le réticulum endoplasmique et l’appareil de Golgi, et de Sec4p, impliquée dans l’exocytose. Gyl1p, qui possède un domaine catalytique partiellement dégénéré, n’a pas d’activité stimulatrice de GTPase connue.

L’objectif de mon travail de thèse était de rechercher les fonctions biologiques de Gyp5p et de Gyl1p.

Nous avons montré que Gyp5p et Gyl1p sont situées aux sites de croissance polarisée, où elles sont co-localisées avec Sec4p. Gyp5p est présente dans un complexe contenant Sec4p dans une fraction enrichie en vésicules post-golgiennes, et Gyp5p et Gyl1p sont présentes dans un complexe contenant Sec4p dans une fraction enrichie en membrane plasmique. SEC2, qui code pour le facteur d’échange de Sec4p, et GYP5 présentent un effet génétique antagoniste par rapport à la croissance cellulaire. Les cellules dépourvues de Gyp5p et Gyl1p présentent des défauts de sécrétion, et accumulent des vésicules uniquement chez les jeunes bourgeons à 13°C. Ces résultats montrent que Gyp5p et Gyl1p sont impliquées dans l’exocytose polarisée.
Gyp5p et Gyl1p présentent une localisation dynamique au cours du cycle cellulaire. Gyp5p et Gyl1p sont co-localisées aux étapes de croissance polarisée, mais sont dissociées au cours de la croissance isotropique. Nous avons montré que Gyp5p est délocalisée en l’absence de Gyl1p, et Gyl1p est délocalisée en l’absence de Gyp5p, ce qui montre que la localisation de Gyp5p et Gyl1p est interdépendante. Nous avons montré que Gyp5p et Gyl1p sont capables d’interagir directement in vitro. Nous avons observé que les sous-unités du polarisome Bni1p, Bud6p et Spa2p sont nécessaires à la localisation de Gyp5p et Gyl1p aux sites de croissance polarisée. Le polarisome est un complexe
dont une des fonctions est de réguler la formation de câbles d’actine au sommet du bourgeon par la formine Bni1p. Des défauts de localisation de Gyp5p et Gyl1p ont également été observés en l’absence de l’autre formine Bnr1p. Ces résultats suggèrent que la localisation de Gyp5p et Gyl1p serait dépendante des câbles d’actine.
Nous avons également montré qu’une partie de Gyp5p et de Gyl1p est présente dans un complexe avec Rvs167p. Rvs167p est une protéine connue pour être impliquée dans l’endocytose. Une partie de Rvs167p est co-localisée avec Gyp5p et Gyl1p aux sites de croissance polarisée. Mais en l’absence de Gyp5p et de Gyl1p, Rvs167p n’est plus présente au sommet des jeunes bourgeons et au cou du bourgeon lors de la cytocinèse. Gyp5p et Gyl1p sont donc nécessaire à la localisation de Rvs167p aux sites de croissance polarisée.

The regular appearance and the repetitive nature of the Drosophila eye, consisting of several hundred identical multicellular units, the ommatidia, has long served as an invaluable experimental system to study cell-cell interactions, inductive signaling events, cell proliferation, programmed cell death, cell differentiation, cell organization, and planar cell polarity among others. Importantly, the eye is dispensable for viability and fertility of the fly and thus, it can easily be manipulated, making it an ideal target for genetic screens. This chapter described an essential technique in the analysis of different genotypes in the adult fly eye, and allows detailed analyses with single cell resolution.

This study demonstrates the utility of Lifeact for the investigation of actin dynamics in Neurospora crassa and also represents the first report of simultaneous live-cell imaging of the actin and microtubule cytoskeletons in filamentous fungi. Lifeact is a 17-amino-acid peptide derived from the nonessential Saccharomyces cerevisiae actin-binding protein Abp140p. Fused to green fluorescent protein (GFP) or red fluorescent protein (TagRFP), Lifeact allowed live-cell imaging of actin patches, cables, and rings in N. crassa without interfering with cellular functions. Actin cables and patches localized to sites of active growth during the establishment and maintenance of cell polarity in germ tubes and conidial anastomosis tubes (CATs). Recurrent phases of formation and retrograde movement of complex arrays of actin cables were observed at growing tips of germ tubes and CATs. Two populations of actin patches exhibiting slow and fast movement were distinguished, and rapid (1.2 um/s) saltatory transport of patches along cables was observed. Actin cables accumulated and subsequently condensed into actin rings associated with septum formation. F-actin organization was markedly different in the tip regions of mature hyphae and in germ tubes. Only mature hyphae displayed a subapical collar of actin patches and a concentration of F-actin within the core of the Spitzenkörper. Coexpression of Lifeact-TagRFP and beta-tubulin–GFP revealed distinct but interrelated localization patterns of F-actin and microtubules during the initiation and maintenance of tip growth.