Connections between Cells and Cellular Activities

Gen1.5MakingConnectionsbetween Speaking and Writing 4/5/08 Copywrite vanDommelen2008 1 TESOL 2008 April 5, 2008 Generation 1.5: Making Connections between Speaking and Writing Deborah vanDommelen San Francisco State University dvan@sfsu.edu http://www.sfsu.edu/~lac/infofacstaff.htm Generation 1.5 Learners at San Francisco State Learning Assistance Center • are generally orally proficient; • communicate in English with ease and facility; • have acquired English in ways similar to native speakers; • have trouble learning and applying grammatical rules; • struggle with conventions of academic English. Assessing Practices; Developing an Approach; Working with Orally Fluent Multilingual Learners 1. Acknowledge and draw upon students’ strengths as oral communicators. 2. Develop activities that help students discover learning preferences: oral, aural, written. 3. Guide students in making connections between how they speak and how they write. 4. Help students raise awareness about the connection between spoken language and written discourse. Activity 1. Warm-Up: Comparing Language Backgrounds and Ways of Learning mimicking teachersSpanglishMarlena in pre-school: reading/writing EnglishMichael home; communityEbonicsJade at homeTagalogLarissa from cousins, schoolChineseAlvin How/when did you learn English? First language you learned? Name Activity 2. Writing Comparing Learning in the Aural Mode with Learning in the Written Mode Directions 1. With a partner, use the information from the introductory activity about how you learned English to come up with two definitions: one for “eye learner” and the other for “ear learner.” Write your definitions on the board. 2. As a large group, discuss the different ideas on the board to decide on two definitions that work for the class. Activity 2. Writing Comparing Learning in the Aural Mode with Learning in the Written Mode Directions 3. With your partner, interview each other using the following question: “Are you an ‘eye-learner’ or ‘ear-learner’ of English? Ask your partner to explain why. Take notes. 4. For homework (on paper or OH transparencies), write a summary of your interview. Gen1.5MakingConnectionsbetween Speaking and Writing 4/5/08 Copywrite vanDommelen2008 2 “Fernando learns better by eye learning. He said that with ear learning only he easily gets bored, but with eye learning, he learns more. He noticed he was a better learner by certain types of eye learning when he was 14 years old, when he read a book and understood nothing, but when he watched a movie and listened to the characters, he understood it all.” “Loan is an eye and ear learner that uses both of her learning experiences to learn more. She uses both most of the time, but she can adopt any of the learning techniques depending on the situations. She said that for chemistry she uses both and for grammar only uses eye learning. She realize that she uses both last night whe she answer the homework question.” Activity 3. Dictocomp: Listening, reconstructing Connections between Cells and Cellular Activities Connections between Cells and Cellular Activities Bởi: OpenStaxCollege You already know that a group of similar cells working together is called a tissue As you might expect, if cells are to work together, they must communicate with each other, just as you need to communicate with others if you work on a group project Let’s take a look at how cells communicate with each other Extracellular Matrix of Animal Cells Most animal cells release materials into the extracellular space The primary components of these materials are proteins, and the most abundant protein is collagen Collagen fibers are interwoven with carbohydrate-containing protein molecules called proteoglycans Collectively, these materials are called the extracellular matrix ([link]) Not only does the extracellular matrix hold the cells together to form a tissue, but it also allows the cells within the tissue to communicate with each other How can this happen? The extracellular matrix consists of a network of proteins and carbohydrates 1/6 Connections between Cells and Cellular Activities Cells have protein receptors on the extracellular surfaces of their plasma membranes When a molecule within the matrix binds to the receptor, it changes the molecular structure of the receptor The receptor, in turn, changes the conformation of the microfilaments positioned just inside the plasma membrane These conformational changes induce chemical signals inside the cell that reach the nucleus and turn “on” or “off” the transcription of specific sections of DNA, which affects the production of associated proteins, thus changing the activities within the cell Blood clotting provides an example of the role of the extracellular matrix in cell communication When the cells lining a blood vessel are damaged, they display a protein receptor called tissue factor When tissue factor binds with another factor in the extracellular matrix, it causes platelets to adhere to the wall of the damaged blood vessel, stimulates the adjacent smooth muscle cells in the blood vessel to contract (thus constricting the blood vessel), and initiates a series of steps that stimulate the platelets to produce clotting factors Intercellular Junctions Cells can also communicate with each other via direct contact, referred to as intercellular junctions There are some differences in the ways that plant and animal cells this Plasmodesmata are junctions between plant cells, whereas animal cell contacts include tight junctions, gap junctions, and desmosomes Plasmodesmata In general, long stretches of the plasma membranes of neighboring plant cells cannot touch one another because they are separated by the cell wall that surrounds each cell ([link]b) How then, can a plant transfer water and other soil nutrients from its roots, through its stems, and to its leaves? Such transport uses the vascular tissues (xylem and phloem) primarily There also exist structural modifications called plasmodesmata (singular = plasmodesma), numerous channels that pass between cell walls of adjacent plant cells, connect their cytoplasm, and enable materials to be transported from cell to cell, and thus throughout the plant ([link]) 2/6 Connections between Cells and Cellular Activities A plasmodesma is a channel between the cell walls of two adjacent plant cells Plasmodesmata allow materials to pass from the cytoplasm of one plant cell to the cytoplasm of an adjacent cell Tight Junctions A tight junction is a watertight seal between two adjacent animal cells ([link]) The cells are held tightly against each other by proteins (predominantly two proteins called claudins and occludins) Tight junctions form watertight connections between adjacent animal cells Proteins create tight junction adherence (credit: modification of work by Mariana Ruiz Villareal) This tight adherence prevents materials from leaking between the cells; tight junctions are typically found in epithelial tissues that line internal organs and cavities, and comprise most of the skin For example, the tight junctions of the epithelial cells lining your urinary bladder prevent urine from leaking out into the extracellular space Desmosomes Also found only in animal cells are desmosomes, which act like spot welds between adjacent epithelial cells ([link]) Short proteins called cadherins in the plasma membrane connect to intermediate filaments to create desmosomes The cadherins join two adjacent cells together and maintain the cells in a sheet-like formation in organs and tissues that stretch, like the skin, heart, and muscles 3/6 Connections between Cells and Cellular Activities A desmosome forms a very strong spot weld between cells It is created by the linkage of cadherins and intermediate filaments (credit: modification of work by Mariana Ruiz Villareal) Gap Junctions Gap junctions in animal cells are like plasmodesmata in plant cells in that they are channels between adjacent cells that allow for the transport ...In vitro analysis of the relationship between endonuclease and maturase activities in the bi-functional group I intron-encoded protein, I-AniI William J. Geese, Yong K. Kwon, Xiaoping Wen and Richard B. Waring Department of Biology, Temple University, Philadelphia, USA The AnCOB group I intron from Aspergillus nidulans encodes a homing DNA endonuclease called I-AniI which also functions as a maturase, assisting in AnCOB intron RNA splicing. In this investigation we biochemically char- acterized the endonuclease activity of I-AniI in vitro and utilized competition assays to probe the relationship between the RNA- and DNA-binding sites. Despite functioning as an RNA maturase, I-AniI still retains several characteristic properties of homing endonucleases including relaxed sub- strate specificity, DNA cleavage product retention and instability in the reaction buffer, which suggest that the protein has not undergone dramatic structural adaptations to function as an RNA-binding protein. Nitrocellulose filter binding and kinetic burst assays showed that both nucleic acids bind I-AniI with the same 1 : 1 stoichiometry. Fur- thermore, in vitro competition activity assays revealed that the RNA substrate, when prebound to I-AniI, stoichio- metrically inhibits DNA cleavage activity, yet in reciprocal experiments, saturating amounts of prebound DNA sub- strate fails to inhibit RNA splicing activity. The data suggest therefore that both nucleic acids do not bind the same single binding site, rather that I-AniI appears to contain two binding sites. Keywords: Aspergillus nidulans; homing endonuclease; RNA binding protein; DNA sliding; RNA splicing. Group I and group II introns frequently contain open reading frames (ORFs), which are either free-standing within the intron itself or are in-frame with the preceding 5¢ exon [1,2]. While some of these encode essential host proteins, others have been shown to encode proteins that facilitate the splicing of their cognate introns. These are called maturases [3]. All known group I maturase proteins are characterized by two repeated LAGLIDADG amino acid motifs [4]. Interestingly, maturases are highly homologous to a class of intron-encoded DNA endonucleases (also found in inteins) [2,5–12] that are characterized by one or two copies of the same LAGLIDADG motif [7,8,13], reviewed in [7]. Intron-encoded DNA endonucleases catalyze the mobi- lization of their cognate intron (or intein) into the equivalent exon sequence of intron-less alleles of the same gene in a process called homing [14]. Significant progress has been made in the past decade in the characterization of homing endonuclease biochemistry and several crystal structures now exist, both with [15–17] and without bound DNA substrate [18–21]. Homing endonucleases containing one LAGLIDADG motif (e.g. I-CreI) are about half the size of those with two copies and structural analysis has shown that they function as homodimers [21]. Double motif-containing endonucleases, including the intein-encoded endonucleases PI-SceI and PI- PfuI as well as the archael intron-encoded protein I-DmoI, were crystallized as monomers [19,20]. Molecular modeling and crystal structure studies suggest that single-motif, homodimer and double-motif, monomeric LAGLIDADG homing endonucleases contain one DNA-binding site and share roughly the same extended overall structure with either two- or pseudo twofold symmetry [19–21], reviewed in [8,13]. The phylogenetic distribution of LAGLIDADG homing endonucleases is REVIEW ARTICLE Functional interplay between viral and cellular SR proteins in control of post-transcriptional gene regulation Ming-Chih Lai 1, *, Tsui-Yi Peng 1,2, * and Woan-Yuh Tarn 1 1 Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan 2 Institute of Molecular Medicine, National Tsing Hua University, Hsin-Chu, Taiwan Introduction Arginine ⁄ serine (RS) dipeptide repeats are present in a number of cellular proteins, termed SR proteins, that primarily participate in nuclear precursor (pre)-mRNA splicing [1–3]. RS domain variants, such as serine and arginine-rich motifs or arginine–aspartate or arginine– glutamate dipeptide-rich domains, are also found in many nuclear proteins. In addition to the RS domains, SR splicing factors often contain one or more RNA recognition motifs. SR proteins function in both constitutive and regulated splicing via binding to cis-elements of pre-mRNA or interaction with other splicing factors. The RS domain interacts with both proteins and RNAs [1–3]. In particular, intermolecular interactions between SR proteins, which are important for spliceosome assembly and splice site determination during pre-mRNA splicing, are mediated by their RS domains [3]. The RS domain also acts as a nuclear localization signal and targets SR proteins to nuclear speckled domains, where splicing factors are concen- trated, for storage [1]. An important biochemical property of the RS domain is its differential phosphorylation at multiple serine and threonine residues. The RS domain is primarily phos- phorylated by SR protein-specific kinases (SRPKs), and Keywords Alternative splicing; kinases; phosphatases; phosphorylation; post-transcriptional control; pre-mRNA splicing; RS domain; SR proteins; viral problems; virus Correspondence W Y. Tarn, Institute of Biomedical Sciences, Academia Sinica, 128 Academy Road, Section 2, Nankang, Taipei 11529, Taiwan Fax: +886 2 2782 9142 Tel: +886 2 2652 3052 E-mail: wtarn@ibms.sinica.edu.tw *These authors contributed equally to this work (Received 3 November 2008, revised 14 December 2008, accepted 9 January 2009) doi:10.1111/j.1742-4658.2009.06894.x Viruses take advantage of cellular machineries to facilitate their gene expression in the host. SR proteins, a superfamily of cellular precursor mRNA splicing factors, contain a domain consisting of repetitive argi- nine ⁄ serine dipeptides, termed the RS domain. The authentic RS domain or variants can also be found in some virus-encoded proteins. Viral pro- teins may act through their own RS domain or through interaction with cellular SR proteins to facilitate viral gene expression. Numerous lines of evidence indicate that cellular SR proteins are important for regulation of viral RNA splicing and participate in other steps of post-transcriptional viral gene expression control. Moreover, viral infection may alter the expression levels or modify the phosphorylation status of cellular SR proteins and thus perturb cellular precursor mRNA splicing. We review our current understanding of the interplay between virus and host in post-transcriptional regulation of gene expression via RS domain-containing proteins. Abbreviations CTE, constitutive transport element; E4, early region 4; EV, epidermodysplasia verruciformis; HBV, hepatitis B virus; HCV, hepatitis C virus; hnRNP, heterogeneous nuclear ribonucleoprotein; HPV, human papillomavirus; HSV, herpes simplex virus; IRES, internal ribosome entry site; N, nucleocapsid; PP, protein phosphatase; RESEARCH Open Access Correlation between antibutyrylcholinesterasic and antioxidant activities of three aqueous extracts from Tunisian Rhus pentaphyllum Hedi Ben Mansour 1* , Sonia Yatouji 2 , Sihem Mbarek 1 , Ikram Houas 1 , Afef Delai 1 and Dorra Dridi 1 Abstract For centuries, plants have been used in traditional medicines and there has been recent interest in the chemopreventive properties of compounds derived from plants. In the present study, we investigated the antibutyrylcholinest rasic (anti-BuChE) and antioxidant (against some free radicals) activities of extracts from Rhus pentaphyllum. Aqueous extracts were prepared from powdered R. pentaphyllum roots, leaves and seeds and characterized for the presence of tannins, flavonoids and coumarins. Seeds aqueous extract contained the highest quantities of both flavonoids and tannins (21.12% and 17.45% respectively). In the same way, seeds extracts displayed remarkable inhibition against BuChE over 95%, at 100 μg/ml and with IC 50 0.74 μg/ml. In addition, compared to leaves and roots extracts, seeds aqueo us extract revealed relatively strong antiradical activity towards the ABTS .+ (IC 50 = 0.25 μg/ml) and DPPH (IC 50 = 2.71 μg/ml) free radicals and decreased significantly the reactive oxygen species such O 2 (IC 50 = 2.9 μg/ml) formation evaluated by the non-enzymatic generating O 2 system (Nitroblue tetrazolium/riboflavine). These data sug gest that the anti-BuChE activities mechanism of these extracts occurs through a free radical scavenging capacities. The present study indicates that extracts of Rhus pentaphyllum leaves, seeds and roots are a significant source of compounds, such as tannins, flavonoids and coumarins, with anti-BuChE and antioxidant activities, and thus may be useful for chemoprevention. Keywords: Rhus pentaphyllum, anti-Butyrylcholinesterasic activity, free radical scavenging activity, antioxidant activity Introduction Alzheimer’s disease (AD) is a degenerative neurological disorder characterized by senile plaques containing amy- loid b protein and loss of cholinergic neuromediators in the brain [1,2]. The most remarkable biochemical change in AD patients is a reduction of acetylcholine (ACh) levels in the hippocampus and cortex of the brain [3]. Therefore, inhibition of acetylcholinesterase (AChE), the enzyme responsible for hydrolysis of ACh at the cholinergic synapse, is currently the most established approach to treating AD [4]. While AChE is found in all excitable tissue, whether nerve or muscle, in most ery- throcytes and in placental tissue, BChE is present more commonly in the body including the central and periph- eral ne rvous system, liver and plasma [5]. On the other hand, oxidative stress caused by react ive oxygen sp ecies (ROS), is known to cause the oxidation of biomolecules leading to cellular damage. It is also speculated to be pathologically important in various neurodegenerative processes including cognitive deficits that occur during normal cerebral aging, Alzheimer’s disease (AD) and Parkinson’s disease [6-8]. Nowaday s, the most accepted theory about the disturb ing effect of free radi cal s in the process of aging was reported by Harman [9]. Later on, it was also reported that oxidative stress is associated with the pathogenesis of AD an d cell ular characteristics of this disease are either causes or effects of oxidative stress [10,11]. These evidences clearly show that oxidative stress, an early event in AD, may play a key pathogenic role in the * Correspondence: hedi.mansour@hotmail.fr 1 Institut Supérieur de Biotechnologie (ISB), Technopole Sidi Thabet, Université la Manouba 2020 Ariana Tunisie Full list of author information is available at the end of the article Mansour et al. Annals of Clinical Microbiology and Antimicrobials 2011, 10:32 http://www.ann-clinmicrob.com/content/10/1/32 © 2011 Mansour et al; licensee BioMed Ce ntral Ltd. This is an Open Access article distributed under the terms of the Creative Commons Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. CO-OPERATION BETWEEN HUMORAL AND CELLULAR IMMUNITY IN PULMONARY LUNG INFLAMMATION DEEPA MOHANAN (B.Sci (Hons), NUS) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF MICROBIOLOGY NATIONAL UNIVERSITY OF SINGAPORE 2008 Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. CO-OPERATION BETWEEN HUMORAL AND CELLULAR IMMUNITY IN PULMONARY LUNG INFLAMMATION DEEPA MOHANAN (B.Sci (Hons), NUS) NATIONAL UNIVERSITY OF SINGAPORE 2008 Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Abstract i ABSTRACT Asthma is a respiratory disease characterised by reversible airway obstruction, elevated levels of immunoglobulin E (IgE) in serum, chronic eosinophilic airway inflammation and airway hyperresponsiveness (AHR) to bronchospasmogenic stimuli. Many studies have been performed to dissect the role of T lymphocytes in asthma but not many studies specifically address the role of IgE in asthma. In vitro studies have shown enhanced activation of allergen specific T cells when they were cultured with allergen and allergen-specific IgE, suggesting that the role of IgE is more than just a mast cell activator but rather it plays a part in up-regulating the effects of CD4+ T cells in asthma. Hence the aim of the current study was to elucidate the interaction between allergen-specific IgE and allergen-specific Th2 CD4+ T cells in vivo. Mice that were immunised by intraperitoneal (i.p.) injection of ovalbumin (OVA) followed by intranasal (i.n.) challenge with OVA had a significantly higher percentage of eosinophils in bronchoalveolar lavage (BAL) compared to the control group animals. Moreover, levels of OVA-specific IgE were a 1000-fold higher in experimental animals than in control animals. To study the role of IgE in airway inflammation, a passive sensitisation model was developed. Mice were intravenously (i.v.) given OVA-specific IgE before they were i.n. challenged with OVA and responses of these mice were analysed by BAL. No eosinophilic inflammation of the airways was observed regardless of the relatively high doses of mouse anti-OVA IgE that were used. To study the role of CD4+ T cells in airway inflammation, Th2-polarised antigen-specific CD4+ T cells were intravenously transferred into naïve animals before they were intranasally challenged with OVA. Massive numbers of eosinophils was recruited into the BAL with the adoptive transfer model mice. Once these two models were independently established, the role of IgE aiding in the airway Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Abstract ii inflammation induced by antigen-specific CD4+ T cells was studied by combining the two models. The mice were passively challenged with IgE and given sub-optimal numbers of Th2 cells a day before they were intranasally challenged with OVA. Mice that had received just the Th2 cells had a higher level of eosinophils in the BAL when compared to animals that were passively sensitised and given Th2 cells. However mice that had received IgE had a higher percentage of T-cells and almost twice the amount of transgenic T-cells recruited into the lungs thus suggesting that IgE might play a role in the recruitment of T-cells but not in the enhancement of T-cell mediated responses. Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Acknowledgements iii ACKNOWLEDGEMENTS I would like to express my gratitude to my supervisor, Prof Kemeny, for giving me the opportunity to work in his lab. Thesis writing would have been hell if I didn’t have valuable feedback and help from these people: Dr Christopher Yang, Pang Shyue Wei and Kenneth Wong. I had great support during the course of my Masters from people of DMK’s lab mainly: Desmond, Soombul, Hema, Dr Betts, Shu Zhen, Yafang, Javier, Benson and many others. Life in lab ... formation in organs and tissues that stretch, like the skin, heart, and muscles 3/6 Connections between Cells and Cellular Activities A desmosome forms a very strong spot weld between cells It is created... junctions, allowing the heart muscle cells to contract in tandem Link to Learning 4/6 Connections between Cells and Cellular Activities To conduct a virtual microscopy lab and review the parts of a cell,.. .Connections between Cells and Cellular Activities Cells have protein receptors on the extracellular surfaces of their plasma membranes When a