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Sapkota, Hem, Emilia Wasiak, John R. Daum, and Gary J. Gorbsky. "Multiple determinants and consequences of cohesion fatigue in mammalian cells." Molecular Biology of the Cell 29, no. 15 (August 2018): 1811–24. http://dx.doi.org/10.1091/mbc.e18-05-0315.
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Cells delayed in metaphase with intact mitotic spindles undergo cohesion fatigue, where sister chromatids separate asynchronously, while cells remain in mitosis. Cohesion fatigue requires release of sister chromatid cohesion. However, the pathways that breach sister chromatid cohesion during cohesion fatigue remain unknown. Using moderate-salt buffers to remove loosely bound chromatin cohesin, we show that “cohesive” cohesin is not released during chromatid separation during cohesion fatigue. Using a regulated protein heterodimerization system to lock different cohesin ring interfaces at specific times in mitosis, we show that the Wapl-mediated pathway of cohesin release is not required for cohesion fatigue. By manipulating microtubule stability and cohesin complex integrity in cell lines with varying sensitivity to cohesion fatigue, we show that rates of cohesion fatigue reflect a dynamic balance between spindle pulling forces and resistance to separation by interchromatid cohesion. Finally, while massive separation of chromatids in cohesion fatigue likely produces inviable cell progeny, we find that short metaphase delays, leading to partial chromatid separation, predispose cells to chromosome missegregation. Thus, complete separation of one or a few chromosomes and/or partial separation of sister chromatids may be an unrecognized but common source of chromosome instability that perpetuates the evolution of malignant cells in cancer.
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Mishra, Prashant K., Sultan Ciftci-Yilmaz, David Reynolds, Wei-Chun Au, Lars Boeckmann, Lauren E. Dittman, Ziad Jowhar, et al. "Polo kinase Cdc5 associates with centromeres to facilitate the removal of centromeric cohesin during mitosis." Molecular Biology of the Cell 27, no. 14 (July 15, 2016): 2286–300. http://dx.doi.org/10.1091/mbc.e16-01-0004.
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Sister chromatid cohesion is essential for tension-sensing mechanisms that monitor bipolar attachment of replicated chromatids in metaphase. Cohesion is mediated by the association of cohesins along the length of sister chromatid arms. In contrast, centromeric cohesin generates intrastrand cohesion and sister centromeres, while highly cohesin enriched, are separated by >800 nm at metaphase in yeast. Removal of cohesin is necessary for sister chromatid separation during anaphase, and this is regulated by evolutionarily conserved polo-like kinase (Cdc5 in yeast, Plk1 in humans). Here we address how high levels of cohesins at centromeric chromatin are removed. Cdc5 associates with centromeric chromatin and cohesin-associated regions. Maximum enrichment of Cdc5 in centromeric chromatin occurs during the metaphase-to-anaphase transition and coincides with the removal of chromosome-associated cohesin. Cdc5 interacts with cohesin in vivo, and cohesin is required for association of Cdc5 at centromeric chromatin. Cohesin removal from centromeric chromatin requires Cdc5 but removal at distal chromosomal arm sites does not. Our results define a novel role for Cdc5 in regulating removal of centromeric cohesins and faithful chromosome segregation.
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Boavida, Ana, Diana Santos, Mohammad Mahtab, and Francesca M. Pisani. "Functional Coupling between DNA Replication and Sister Chromatid Cohesion Establishment." International Journal of Molecular Sciences 22, no. 6 (March 10, 2021): 2810. http://dx.doi.org/10.3390/ijms22062810.
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Several lines of evidence suggest the existence in the eukaryotic cells of a tight, yet largely unexplored, connection between DNA replication and sister chromatid cohesion. Tethering of newly duplicated chromatids is mediated by cohesin, an evolutionarily conserved hetero-tetrameric protein complex that has a ring-like structure and is believed to encircle DNA. Cohesin is loaded onto chromatin in telophase/G1 and converted into a cohesive state during the subsequent S phase, a process known as cohesion establishment. Many studies have revealed that down-regulation of a number of DNA replication factors gives rise to chromosomal cohesion defects, suggesting that they play critical roles in cohesion establishment. Conversely, loss of cohesin subunits (and/or regulators) has been found to alter DNA replication fork dynamics. A critical step of the cohesion establishment process consists in cohesin acetylation, a modification accomplished by dedicated acetyltransferases that operate at the replication forks. Defects in cohesion establishment give rise to chromosome mis-segregation and aneuploidy, phenotypes frequently observed in pre-cancerous and cancerous cells. Herein, we will review our present knowledge of the molecular mechanisms underlying the functional link between DNA replication and cohesion establishment, a phenomenon that is unique to the eukaryotic organisms.
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Bonner, Pamela J., and Lawrence J. Shimkets. "Cohesion-Defective Mutants of Myxococcus xanthus." Journal of Bacteriology 188, no. 12 (June 15, 2006): 4585–88. http://dx.doi.org/10.1128/jb.00237-06.
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ABSTRACT Cohesion of Myxococcus xanthus cells involves interaction of a cell surface cohesin with a component of the extracellular matrix. In this work, two previously isolated cohesion-defective (fbd) mutants were characterized. The fbdA and fbdB genes do not encode the cohesins but are necessary for their production. Both mutants produce type IV pili, suggesting that PilA is not a major cohesin.
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Shi, Di, Shuaijun Zhao, Mei-Qing Zuo, Jingjing Zhang, Wenya Hou, Meng-Qiu Dong, Qinhong Cao, and Huiqiang Lou. "The acetyltransferase Eco1 elicits cohesin dimerization during S phase." Journal of Biological Chemistry 295, no. 22 (April 20, 2020): 7554–65. http://dx.doi.org/10.1074/jbc.ra120.013102.
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Cohesin is a DNA-associated protein complex that forms a tripartite ring controlling sister chromatid cohesion, chromosome segregation and organization, DNA replication, and gene expression. Sister chromatid cohesion is established by the protein acetyltransferase Eco1, which acetylates two conserved lysine residues on the cohesin subunit Smc3 and thereby ensures correct chromatid separation in yeast (Saccharomyces cerevisiae) and other eukaryotes. However, the consequence of Eco1-catalyzed cohesin acetylation is unknown, and the exact nature of the cohesive state of chromatids remains controversial. Here, we show that self-interactions of the cohesin subunits Scc1/Rad21 and Scc3 occur in a DNA replication–coupled manner in both yeast and human cells. Using cross-linking MS-based and in vivo disulfide cross-linking analyses of purified cohesin, we show that a subpopulation of cohesin may exist as dimers. Importantly, upon temperature-sensitive and auxin-induced degron-mediated Eco1 depletion, the cohesin-cohesin interactions became significantly compromised, whereas deleting either the deacetylase Hos1 or the Eco1 antagonist Wpl1/Rad61 increased cohesin dimer levels by ∼20%. These results indicate that cohesin dimerizes in the S phase and monomerizes in mitosis, processes that are controlled by Eco1, Wpl1, and Hos1 in the sister chromatid cohesion-dissolution cycle. These findings suggest that cohesin dimerization is controlled by the cohesion cycle and support the notion that a double-ring cohesin model operates in sister chromatid cohesion.
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Utomo, Slamet, and Dita Indah Sekti. "COHESION IN ANNE HATHAWAY’S SPEECH TEXT ON “PAID PARENTAL LEAVE IS ABOUT CREATING FREEDOM TO DEFINE ROLES”." KREDO : Jurnal Ilmiah Bahasa dan Sastra 2, no. 2 (April 20, 2019): 325–37. http://dx.doi.org/10.24176/kredo.v2i2.3344.
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This research aims to identify the grammatical and lexical cohesion used in Anne Hathaway’s speech text on “Paid Parental Leave is about Creating Freedom to Define Roles”, and interpret how grammatical and lexical cohesion are used in Anne Hathaway’s speech text on “Paid Parental Leave is about Creating Freedom to Define Roles”.The type of this research is descriptive qualitative research. The result of this research shows that all types of grammatical and lexical cohesion are used in the speech text. For the grammatical cohesions are: reference (personal, demonstrative and comparative reference), substitution (nominal substitution), ellipsis (verbal and clausal ellipsis) and conjunction (additive, adversative, causal and temporal conjunction). Meanwhile, the lexical cohesions are: reiteration (repetition, synonym, superordinate and general word) and collocation. The most dominant of cohesive devices used in the speech text is reference especially for personal reference. All those cohesive devices are used clearly, it means that the speech text of Anne Hathaway entitled “Paid Parental Leave is about Creating Freedom to Define Roles” used grammatical and lexical cohesion well. Finally, the writer suggests that cohesion is important to be studied in language learning because cohesion can be used as a strategy to construct and comprehend any text especially for speech.
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Brar, Gloria A., Andreas Hochwagen, Ly-sha S. Ee, and Angelika Amon. "The Multiple Roles of Cohesin in Meiotic Chromosome Morphogenesis and Pairing." Molecular Biology of the Cell 20, no. 3 (February 2009): 1030–47. http://dx.doi.org/10.1091/mbc.e08-06-0637.
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Sister chromatid cohesion, mediated by cohesin complexes, is laid down during DNA replication and is essential for the accurate segregation of chromosomes. Previous studies indicated that, in addition to their cohesion function, cohesins are essential for completion of recombination, pairing, meiotic chromosome axis formation, and assembly of the synaptonemal complex (SC). Using mutants in the cohesin subunit Rec8, in which phosphorylated residues were mutated to alanines, we show that cohesin phosphorylation is not only important for cohesin removal, but that cohesin's meiotic prophase functions are distinct from each other. We find pairing and SC formation to be dependent on Rec8, but independent of the presence of a sister chromatid and hence sister chromatid cohesion. We identified mutations in REC8 that differentially affect Rec8's cohesion, pairing, recombination, chromosome axis and SC assembly function. These findings define Rec8 as a key determinant of meiotic chromosome morphogenesis and a central player in multiple meiotic events.
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Adiantika, Hanif Nurcholish. "The Contribution of Lexical Cohesion to the Text Cohesion in EFL Students’ Expository Texts." ELT in Focus 1, no. 1 (June 15, 2018): 11–18. http://dx.doi.org/10.35706/eltinfc.v1i1.1294.
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This study aims to investigate the use of lexical cohesion in students’ expository texts. It reveals thetypes of lexical cohesion employed by the students in their expository texts and the contribution oflexical cohesion to the text’ cohesion. This study employs qualitative research by using a case studydesign. Nine students of twelfth grade in a public senior high school in Kuningan regent, West Java,are chosen as the participants. The data in this study include the documents of students’ expositorytexts. The data are analyzed by using the concept of cohesive devices proposed by Halliday andHasan (1976). The findings show that there are two lexical cohesions identified in nine students’expository texts i.e. reiteration (covering i.e. antonymy, repetition, synonymy, meronymy, andhyponymy) and collocation. This study also indicates that lexical cohesion contribute to the processof keeping track of the participants and engaging the readers to the core argument of the text.Moreover, it can be stated that the contribution of lexical cohesion towards students’ expositorytexts is considered low. Therefore, there must be an encouragement for the students to use properlexical cohesion to make their text more cohesive.
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Puspitasari, Mega, Andayani Andayani, and Sarwiji Suwandi. "Grammatical and Lexical Cohesion as Students’ Language Ability in Composing Sentences of Observation Report Texts." International Journal of Multicultural and Multireligious Understanding 7, no. 10 (November 5, 2020): 354. http://dx.doi.org/10.18415/ijmmu.v7i10.2088.
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This study aims to 1) describe the grammatical and lexical cohesion used by the students to compose sentences of the observation report text and 2) explain the role of grammatical and lexical cohesion in the students' observation report texts. The data source of this research was students as many as 70 people with 70 written text data of student observation reports. The analysis results showed that the use of grammatical cohesion which includes pronoun and conjunction. Lexical cohesion includes repetition, antonym, synonym, and hyponym. The roles of the two cohesions can help students to develop sentences to be cohesive.
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Tong, Kevin, and Robert V. Skibbens. "Pds5 regulators segregate cohesion and condensation pathways in Saccharomyces cerevisiae." Proceedings of the National Academy of Sciences 112, no. 22 (May 18, 2015): 7021–26. http://dx.doi.org/10.1073/pnas.1501369112.
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Cohesins are required both for the tethering together of sister chromatids (termed cohesion) and subsequent condensation into discrete structures—processes fundamental for faithful chromosome segregation into daughter cells. Differentiating between cohesin roles in cohesion and condensation would provide an important advance in studying chromatin metabolism. Pds5 is a cohesin-associated factor that is essential for both cohesion maintenance and condensation. Recent studies revealed that ELG1 deletion suppresses the temperature sensitivity of pds5 mutant cells. However, the mechanisms through which Elg1 may regulate cohesion and condensation remain unknown. Here, we report that ELG1 deletion from pds5-1 mutant cells results in a significant rescue of cohesion, but not condensation, defects. Based on evidence that Elg1 unloads the DNA replication clamp PCNA from DNA, we tested whether PCNA overexpression would similarly rescue pds5-1 mutant cell cohesion defects. The results indeed reveal that elevated levels of PCNA rescue pds5-1 temperature sensitivity and cohesion defects, but do not rescue pds5-1 mutant cell condensation defects. In contrast, RAD61 deletion rescues the condensation defect, but importantly, neither the temperature sensitivity nor cohesion defects exhibited by pds5-1 mutant cells. In combination, these findings reveal that cohesion and condensation are separable pathways and regulated in nonredundant mechanisms. These results are discussed in terms of a new model through which cohesion and condensation are spatially regulated.
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Bloom, Kerry. "Liberating cohesin from cohesion." Genes & Development 31, no. 21 (November 1, 2017): 2113–14. http://dx.doi.org/10.1101/gad.309732.117.
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Noprival, Noprival, Alfian Alfian, and Robi Soma. "Analyzing Grammatical and Lexical Cohesion in A Legendary Short Story." Indonesian Journal of EFL and Linguistics 7, no. 2 (November 24, 2022): 251. http://dx.doi.org/10.21462/ijefl.v7i2.488.
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Analyzing Grammatical and Lexical Cohesion in A Legendary Short Story Noprival Sekolah Tinggi Ilmu Kesehatan Harapan Ibu Jambi, Jambi, Indonesiae-mail: noprival@gmail.com (corresponding author) Alfian Universitas Islam Negeri Sulthan Thaha Saifuddin Jambi, Jambi, Indonesiae-mail: alfian@uinjambi.ac.id Robi SomaUniversitas Jambi, Jambi, Indonesiae-mail: robisoma858@unja.ac.id Abstract:Despite the existence of many studies on cohesion in discourse, little scholarly work reports grammatical and lexical cohesion in a short story. To fill this gap, the present study investigates these two aspects of cohesion in a legendary short story entitled “After Twenty Years.” Halliday and Hasan’s (1976) theoretical framework of cohesion was used to guide the current study. We applied textual analysis as the appropriate approach to find out grammatical and lexical cohesion within the forms of text. The findings in the grammatical cohesions showed that reference had the highest frequency of the total cohesive devices. Also, under grammatical cohesion, conjunctions are found to exist. However, other aspects were not found within this short story, including substitution and ellipsis. On the other hand, repetition was dominantly used lexically among other aspects of lexical cohesion and sequentially followed by repetitions, hyponyms, synonyms, and antonyms. Only one aspect of lexical cohesion, the meronym, was not found. The overall results of the research indicated that the short story was a coherent discourse because both grammatical and lexical cohesion exist properly.
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Bunga, Rosa Dalima. "Kekohesifan Dalam Antologi Cerpen Wajah Indoenesiaku Karya Siswa SMA Flores Lembata." Ekspektasi: Jurnal Pendidikan Ekonomi 2, no. 1 (April 3, 2017): 23–33. http://dx.doi.org/10.37478/jpe.v2i1.102.
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One of discourse structure is the element of cohesion. Cohesion is the bonds and relationships that exist in the text. According to Halliday and Hassan, cohesion consists of two kinds, namely lexicaland grammatical elements.The grammatical cohesion is a device or a marker which involves the use of language rules elements. The grammatical cohesion devices that are used to connect the idea among sentences is fairly limited, that are pronouns, nominate, noun phrases, and clausa. While the lexical cohesion namely words or free phrases are able to maintain the cohesive relationship with the sentences preceded or followed. There are two kinds of lexical cohesion, namely reiterasi (repetition) and collocation of words that indicateda close relationship of the place (location).The source of datain this researchis the short storiesanthology“Wajah Indonesiaku”written by Senior High School Students in Lembata, Flores . The writer only focussing on two short stories, they areMutiara di Pantai Oa written by Karolina Karmalinda and Awan Hitam Selimut Bangsakuby Donatus Doni Koli. There were two kinds of cohession that are found in both short stories, they are grammatical and lexical cohesion. Grammatical cohesion consists of personal pronouns, additive (addition) and sequential (sequence) conjunction. While the lexical cohesion consist of repetition (reduplication), hyponymy and hypernymy. Lexical repetion (reduplication) consist of a full repetition, repetition with other forms, and repeat with the replacement.
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Sumara, Izabela, Elisabeth Vorlaufer, Christian Gieffers, Beate H. Peters, and Jan-Michael Peters. "Characterization of Vertebrate Cohesin Complexes and Their Regulation in Prophase." Journal of Cell Biology 151, no. 4 (November 13, 2000): 749–62. http://dx.doi.org/10.1083/jcb.151.4.749.
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In eukaryotes, sister chromatids remain connected from the time of their synthesis until they are separated in anaphase. This cohesion depends on a complex of proteins called cohesins. In budding yeast, the anaphase-promoting complex (APC) pathway initiates anaphase by removing cohesins from chromosomes. In vertebrates, cohesins dissociate from chromosomes already in prophase. To study their mitotic regulation we have purified two 14S cohesin complexes from human cells. Both complexes contain SMC1, SMC3, SCC1, and either one of the yeast Scc3p orthologs SA1 and SA2. SA1 is also a subunit of 14S cohesin in Xenopus. These complexes interact with PDS5, a protein whose fungal orthologs have been implicated in chromosome cohesion, condensation, and recombination. The bulk of SA1- and SA2-containing complexes and PDS5 are chromatin-associated until they become soluble from prophase to telophase. Reconstitution of this process in mitotic Xenopus extracts shows that cohesin dissociation does neither depend on cyclin B proteolysis nor on the presence of the APC. Cohesins can also dissociate from chromatin in the absence of cyclin-dependent kinase 1 activity. These results suggest that vertebrate cohesins are regulated by a novel prophase pathway which is distinct from the APC pathway that controls cohesins in yeast.
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Nijat, Nazifullah. "Cohesion in News Articles: A Discourse Analysis of Two News Articles From BBC And TOLO News About Overturning The Courts’ Decision For Ahmad Omar Sheikh." Aksara: Jurnal Ilmu Pendidikan Nonformal 8, no. 1 (January 1, 2022): 7. http://dx.doi.org/10.37905/aksara.8.1.7-18.2022.
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<p>The purpose of the current study is to identify various types of cohesive devices and their usage in the selected news articles about the courts’ decision for British-born Ahmed Omar Saeed Sheikh who is convicted of killing US journalist Daniel Pearl; published in Tolo News and BBC News websites. The data is analysed based on the cohesion model proposed by Holiday and Hasan (1976). Cohesions are semantic connections or “relationships of meanings within the text that describe it as a text” (Halliday and Hasan, 1976). The findings of the study show that grammatical cohesive devices containing references, conjunctions, substitution and ellipsis as well as lexical cohesions involving repetitions and collocations were found in both news articles. Among other grammatical cohesive devices, references were found to be frequently used in both news articles while repetitions were the most frequently occurred cohesive devices among lexical cohesion. It can be concluded that all the mentioned cohesive devices employed in the text ultimately contributed to the meaning of the text by binding it in an organised way. It also has been observed that writers use cohesions to give a sense of connection and order to the text.</p>
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Ochs, Fena, Charlotte Green, Aleksander Tomasz Szczurek, Lior Pytowski, Sofia Kolesnikova, Jill Brown, Daniel Wolfram Gerlich, Veronica Buckle, Lothar Schermelleh, and Kim Ashley Nasmyth. "Sister chromatid cohesion is mediated by individual cohesin complexes." Science 383, no. 6687 (March 8, 2024): 1122–30. http://dx.doi.org/10.1126/science.adl4606.
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Eukaryotic genomes are organized by loop extrusion and sister chromatid cohesion, both mediated by the multimeric cohesin protein complex. Understanding how cohesin holds sister DNAs together, and how loss of cohesion causes age-related infertility in females, requires knowledge as to cohesin’s stoichiometry in vivo. Using quantitative super-resolution imaging, we identified two discrete populations of chromatin-bound cohesin in postreplicative human cells. Whereas most complexes appear dimeric, cohesin that localized to sites of sister chromatid cohesion and associated with sororin was exclusively monomeric. The monomeric stoichiometry of sororin:cohesin complexes demonstrates that sister chromatid cohesion is conferred by individual cohesin rings, a key prediction of the proposal that cohesion arises from the co-entrapment of sister DNAs.
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Stead, Kristen, Cristina Aguilar, Theresa Hartman, Melissa Drexel, Pamela Meluh, and Vincent Guacci. "Pds5p regulates the maintenance of sister chromatid cohesion and is sumoylated to promote the dissolution of cohesion." Journal of Cell Biology 163, no. 4 (November 17, 2003): 729–41. http://dx.doi.org/10.1083/jcb.200305080.
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Pds5p and the cohesin complex are required for sister chromatid cohesion and localize to the same chromosomal loci over the same cell cycle window. However, Pds5p and the cohesin complex likely have distinct roles in cohesion. We report that pds5 mutants establish cohesion, but during mitosis exhibit precocious sister dissociation. Thus, unlike the cohesin complex, which is required for cohesion establishment and maintenance, Pds5p is required only for maintenance. We identified SMT4, which encodes a SUMO isopeptidase, as a high copy suppressor of both the temperature sensitivity and precocious sister dissociation of pds5 mutants. In contrast, SMT4 does not suppress temperature sensitivity of cohesin complex mutants. Pds5p is SUMO conjugated, with sumoylation peaking during mitosis. SMT4 overexpression reduces Pds5p sumoylation, whereas smt4 mutants have increased Pds5p sumoylation. smt4 mutants were previously shown to be defective in cohesion maintenance during mitosis. These data provide the first link between a protein required for cohesion, Pds5p, and sumoylation, and suggest that Pds5p sumoylation promotes the dissolution of cohesion.
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Borrie, Melinda S., John S. Campor, Hansa Joshi, and Marc R. Gartenberg. "Binding, sliding, and function of cohesin during transcriptional activation." Proceedings of the National Academy of Sciences 114, no. 7 (January 30, 2017): E1062—E1071. http://dx.doi.org/10.1073/pnas.1617309114.
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The ring-shaped cohesin complex orchestrates long-range DNA interactions to mediate sister chromatid cohesion and other aspects of chromosome structure and function. In the yeast Saccharomyces cerevisiae, the complex binds discrete sites along chromosomes, including positions within and around genes. Transcriptional activity redistributes the complex to the 3′ ends of convergently oriented gene pairs. Despite the wealth of information about where cohesin binds, little is known about cohesion at individual chromosomal binding sites and how transcription affects cohesion when cohesin complexes redistribute. In this study, we generated extrachromosomal DNA circles to study cohesion in response to transcriptional induction of a model gene, URA3. Functional cohesin complexes loaded onto the locus via a poly(dA:dT) tract in the gene promoter and mediated cohesion before induction. Upon transcription, the fate of these complexes depended on whether the DNA was circular or not. When gene activation occurred before DNA circularization, cohesion was lost. When activation occurred after DNA circularization, cohesion persisted. The presence of a convergently oriented gene also prevented transcription-driven loss of functional cohesin complexes, at least in M phase-arrested cells. The results are consistent with cohesin binding chromatin in a topological embrace and with transcription mobilizing functional complexes by sliding them along DNA.
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Eng, Thomas, Vincent Guacci, and Doug Koshland. "ROCC, a conserved region in cohesin's Mcd1 subunit, is essential for the proper regulation of the maintenance of cohesion and establishment of condensation." Molecular Biology of the Cell 25, no. 16 (August 15, 2014): 2351–64. http://dx.doi.org/10.1091/mbc.e14-04-0929.
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Cohesin helps orchestrate higher-order chromosome structure, thereby promoting sister chromatid cohesion, chromosome condensation, DNA repair, and transcriptional regulation. To elucidate how cohesin facilitates these diverse processes, we mutagenized Mcd1p, the kleisin regulatory subunit of budding yeast cohesin. In the linker region of Mcd1p, we identified a novel evolutionarily conserved 10–amino acid cluster, termed the regulation of cohesion and condensation (ROCC) box. We show that ROCC promotes cohesion maintenance by protecting a second activity of cohesin that is distinct from its stable binding to chromosomes. The existence of this second activity is incompatible with the simple embrace mechanism of cohesion. In addition, we show that the ROCC box is required for the establishment of condensation. We provide evidence that ROCC controls cohesion maintenance and condensation establishment through differential functional interactions with Pds5p and Wpl1p.
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Chen, Yu-Fan, Chia-Ching Chou, and Marc R. Gartenberg. "Determinants of Sir2-Mediated, Silent Chromatin Cohesion." Molecular and Cellular Biology 36, no. 15 (May 16, 2016): 2039–50. http://dx.doi.org/10.1128/mcb.00057-16.
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Cohesin associates with distinct sites on chromosomes to mediate sister chromatid cohesion. Single cohesin complexes are thought to bind by encircling both sister chromatids in a topological embrace. Transcriptionally repressed chromosomal domains in the yeastSaccharomyces cerevisiaerepresent specialized sites of cohesion where cohesin binds silent chromatin in a Sir2-dependent fashion. In this study, we investigated the molecular basis for Sir2-mediated cohesion. We identified a cluster of charged surface residues of Sir2, collectively termed the EKDK motif, that are required for cohesin function. In addition, we demonstrated that Esc8, a Sir2-interacting factor, is also required for silent chromatin cohesion. Esc8 was previously shown to associate with Isw1, the enzymatic core of ISW1 chromatin remodelers, to form a variant of the ISW1a chromatin remodeling complex. WhenESC8was deleted or the EKDK motif was mutated, cohesin binding at silenced chromatin domains persisted but cohesion of the domains was abolished. The data are not consistent with cohesin embracing both sister chromatids within silent chromatin domains. Transcriptional silencing remains largely intact in strains lackingESC8or bearing EKDK mutations, indicating that silencing and cohesion are separable functions of Sir2 and silent chromatin.
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Guacci, Vincent, Jeremiah Stricklin, Michelle S. Bloom, Xuánzōng Guō, Meghna Bhatter, and Douglas Koshland. "A novel mechanism for the establishment of sister chromatid cohesion by the ECO1 acetyltransferase." Molecular Biology of the Cell 26, no. 1 (January 2015): 117–33. http://dx.doi.org/10.1091/mbc.e14-08-1268.
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Cohesin complex mediates cohesion between sister chromatids, which promotes high-fidelity chromosome segregation. Eco1p acetylates the cohesin subunit Smc3p during S phase to establish cohesion. The current model posits that this Eco1p-mediated acetylation promotes establishment by abrogating the ability of Wpl1p to destabilize cohesin binding to chromosomes. Here we present data from budding yeast that is incompatible with this Wpl1p-centric model. Two independent in vivo assays show that a wpl1∆ fails to suppress cohesion defects of eco1∆ cells. Moreover, a wpl1∆ also fails to suppress cohesion defects engendered by blocking just the essential Eco1p acetylation sites on Smc3p (K112, K113). Thus removing WPL1 inhibition is insufficient for generating cohesion without ECO1 activity. To elucidate how ECO1 promotes cohesion, we conducted a genetic screen and identified a cohesion activator mutation in the SMC3 head domain (D1189H). Smc3-D1189H partially restores cohesion in eco1∆ wpl1∆ or eco1 mutant cells but robustly restores cohesion in cells blocked for Smc3p K112 K113 acetylation. These data support two important conclusions. First, acetylation of the K112 K113 region by Eco1p promotes cohesion establishment by altering Smc3p head function independent of its ability to antagonize Wpl1p. Second, Eco1p targets other than Smc3p K112 K113 are necessary for efficient establishment.
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Nishiyama, Tomoko. "Cohesion and cohesin-dependent chromatin organization." Current Opinion in Cell Biology 58 (June 2019): 8–14. http://dx.doi.org/10.1016/j.ceb.2018.11.006.
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Mehta, Gunjan D., Ravinder Kumar, Sanjeeva Srivastava, and Santanu Kumar Ghosh. "Cohesin: Functions beyond sister chromatid cohesion." FEBS Letters 587, no. 15 (July 3, 2013): 2299–312. http://dx.doi.org/10.1016/j.febslet.2013.06.035.
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McNally, Karen P., Elizabeth A. Beath, Brennan M. Danlasky, Consuelo Barroso, Ting Gong, Wenzhe Li, Enrique Martinez-Perez, and Francis J. McNally. "Cohesin is required for meiotic spindle assembly independent of its role in cohesion in C. elegans." PLOS Genetics 18, no. 10 (October 24, 2022): e1010136. http://dx.doi.org/10.1371/journal.pgen.1010136.
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Accurate chromosome segregation requires a cohesin-mediated physical attachment between chromosomes that are to be segregated apart, and a bipolar spindle with microtubule plus ends emanating from exactly two poles toward the paired chromosomes. We asked whether the striking bipolar structure of C. elegans meiotic chromosomes is required for bipolarity of acentriolar female meiotic spindles by time-lapse imaging of mutants that lack cohesion between chromosomes. Both a spo-11 rec-8 coh-4 coh-3 quadruple mutant and a spo-11 rec-8 double mutant entered M phase with separated sister chromatids lacking any cohesion. However, the quadruple mutant formed an apolar spindle whereas the double mutant formed a bipolar spindle that segregated chromatids into two roughly equal masses. Residual non-cohesive COH-3/4-dependent cohesin on separated sister chromatids of the double mutant was sufficient to recruit haspin-dependent Aurora B kinase, which mediated bipolar spindle assembly in the apparent absence of chromosomal bipolarity. We hypothesized that cohesin-dependent Aurora B might activate or inhibit spindle assembly factors in a manner that would affect their localization on chromosomes and found that the chromosomal localization patterns of KLP-7 and CLS-2 correlated with Aurora B loading on chromosomes. These results demonstrate that cohesin is essential for spindle assembly and chromosome segregation independent of its role in sister chromatid cohesion.
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Eijpe, Maureen, Hildo Offenberg, Rolf Jessberger, Ekaterina Revenkova, and Christa Heyting. "Meiotic cohesin REC8 marks the axial elements of rat synaptonemal complexes before cohesins SMC1β and SMC3." Journal of Cell Biology 160, no. 5 (March 3, 2003): 657–70. http://dx.doi.org/10.1083/jcb.200212080.
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In meiotic prophase, the sister chromatids of each chromosome develop a common axial element (AE) that is integrated into the synaptonemal complex (SC). We analyzed the incorporation of sister chromatid cohesion proteins (cohesins) and other AE components into AEs. Meiotic cohesin REC8 appeared shortly before premeiotic S phase in the nucleus and formed AE-like structures (REC8-AEs) from premeiotic S phase on. Subsequently, meiotic cohesin SMC1β, cohesin SMC3, and AE proteins SCP2 and SCP3 formed dots along REC8-AEs, which extended and fused until they lined REC8-AEs along their length. In metaphase I, SMC1β, SMC3, SCP2, and SCP3 disappeared from the chromosome arms and accumulated around the centromeres, where they stayed until anaphase II. In striking contrast, REC8 persisted along the chromosome arms until anaphase I and near the centromeres until anaphase II. We propose that REC8 provides a basis for AE formation and that the first steps in AE assembly do not require SMC1β, SMC3, SCP2, and SCP3. Furthermore, SMC1β, SMC3, SCP2, and SCP3 cannot provide arm cohesion during metaphase I. We propose that REC8 then provides cohesion. RAD51 and/or DMC1 coimmunoprecipitates with REC8, suggesting that REC8 may also provide a basis for assembly of recombination complexes.
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Afzaal, Muhammad, Kaibao Hu, Muhammad Ilyas Chishti, and Muhammad Imran. "A Study of Pakistani English Newspaper Texts: An Application of Halliday and Hasan’s Model of Cohesion: A Discourse Analysis." International Journal of English Linguistics 9, no. 5 (August 26, 2019): 78. http://dx.doi.org/10.5539/ijel.v9n5p78.
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This article aims to examine the patterns of each type of cohesive device in light of the cohesion model proposed by Halliday and Hasan in 1976. Halliday and Hasan identified five different types of cohesion: reference, substitution, ellipsis, conjunction and lexical cohesion in the text. This study uses the selected weekly articles authored by Cyril Almeida from well-known daily published English Newspaper “The Daily Dawn”. Analysis of text comprises Halliday and Hasan’s cohesion model, and analyzes linguistic techniques used in newspaper texts. The study finds repeated occurrences of cohesive devices such as referencing, substitution, ellipsis, conjunction, and lexical cohesion. Moreover, reiteration is found to be the most frequently occurring cohesive device. Reference from grammatical cohesion also outnumbers all other subcategories of cohesion. In addition, many of the literary terms employed in articles make it diverse in uncovering some of the political contexts to the audience. Hence, it concludes that in the overall occurrences of lexical cohesion, reiteration and collocation are dominant; suggesting that the texts of selected news articles of Cyril Almeida are cohesive mainly because of lexical cohesion, i.e. semantic linkage through vocabulary rather than grammar.
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Alomer, Reem M., Eulália M. L. da Silva, Jingrong Chen, Katarzyna M. Piekarz, Katherine McDonald, Courtney G. Sansam, Christopher L. Sansam, and Susannah Rankin. "Esco1 and Esco2 regulate distinct cohesin functions during cell cycle progression." Proceedings of the National Academy of Sciences 114, no. 37 (August 28, 2017): 9906–11. http://dx.doi.org/10.1073/pnas.1708291114.
Full textAbstract:
Sister chromatids are tethered together by the cohesin complex from the time they are made until their separation at anaphase. The ability of cohesin to tether sister chromatids together depends on acetylation of its Smc3 subunit by members of the Eco1 family of cohesin acetyltransferases. Vertebrates express two orthologs of Eco1, called Esco1 and Esco2, both of which are capable of modifying Smc3, but their relative contributions to sister chromatid cohesion are unknown. We therefore set out to determine the precise contributions of Esco1 and Esco2 to cohesion in vertebrate cells. Here we show that cohesion establishment is critically dependent upon Esco2. Although most Smc3 acetylation is Esco1 dependent, inactivation of the ESCO1 gene has little effect on mitotic cohesion. The unique ability of Esco2 to promote cohesion is mediated by sequences in the N terminus of the protein. We propose that Esco1-dependent modification of Smc3 regulates almost exclusively the noncohesive activities of cohesin, such as DNA repair, transcriptional control, chromosome loop formation, and/or stabilization. Collectively, our data indicate that Esco1 and Esco2 contribute to distinct and separable activities of cohesin in vertebrate cells.
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Eng, Thomas, Vincent Guacci, and Douglas Koshland. "Interallelic complementation provides functional evidence for cohesin–cohesin interactions on DNA." Molecular Biology of the Cell 26, no. 23 (November 15, 2015): 4224–35. http://dx.doi.org/10.1091/mbc.e15-06-0331.
Full textAbstract:
The cohesin complex (Mcd1p, Smc1p, Smc3p, and Scc3p) has multiple roles in chromosome architecture, such as promoting sister chromatid cohesion, chromosome condensation, DNA repair, and transcriptional regulation. The prevailing embrace model for sister chromatid cohesion posits that a single cohesin complex entraps both sister chromatids. We report interallelic complementation between pairs of nonfunctional mcd1 alleles (mcd1-1 and mcd1-Q266) or smc3 alleles (smc3-42 and smc3-K113R). Cells bearing individual mcd1 or smc3 mutant alleles are inviable and defective for both sister chromatid cohesion and condensation. However, cells coexpressing two defective mcd1 or two defective smc3 alleles are viable and have cohesion and condensation. Because cohesin contains only a single copy of Smc3p or Mcd1p, these examples of interallelic complementation must result from interplay or communication between the two defective cohesin complexes, each harboring one of the mutant allele products. Neither mcd1-1p nor smc3-42p is bound to chromosomes when expressed individually at its restrictive temperature. However, their chromosome binding is restored when they are coexpressed with their chromosome-bound interallelic complementing partner. Our results support a mechanism by which multiple cohesin complexes interact on DNA to mediate cohesion and condensation.
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Nakamura, Akito, Hiroyuki Arai, and Naoya Fujita. "Centrosomal Aki1 and cohesin function in separase-regulated centriole disengagement." Journal of Cell Biology 187, no. 5 (November 23, 2009): 607–14. http://dx.doi.org/10.1083/jcb.200906019.
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Sister chromatid separation at anaphase is triggered by cleavage of the cohesin subunit Scc1, which is mediated by separase. Centriole disengagement also requires separase. This dual role of separase permits concurrent control of these events for accurate metaphase to anaphase transition. Although the molecular mechanism underlying sister chromatid cohesion has been clarified, that of centriole cohesion is poorly understood. In this study, we show that Akt kinase–interacting protein 1 (Aki1) localizes to centrosomes and regulates centriole cohesion. Aki1 depletion causes formation of multipolar spindles accompanied by centriole splitting, which is separase dependent. We also show that cohesin subunits localize to centrosomes and that centrosomal Scc1 is cleaved by separase coincidentally with chromatin Scc1, suggesting a role of Scc1 as a connector of centrioles as well as sister chromatids. Interestingly, Scc1 depletion strongly induces centriole splitting. Furthermore, Aki1 interacts with cohesin in centrosomes, and this interaction is required for centriole cohesion. We demonstrate that centrosome-associated Aki1 and cohesin play pivotal roles in preventing premature cleavage in centriole cohesion.
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Zarepour, Fatemeh. "Cohesion Analysis of Iranian Advanced EFL Learners’ Writing." Journal of Language Teaching and Research 7, no. 2 (March 3, 2016): 408. http://dx.doi.org/10.17507/jltr.0702.23.
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This study seeks to examine the most common cohesive devices used by Iranian advance EFL learners in writing a composition. This study also tries to determine the most common cohesive errors committed by the learners and find probable sources of errors. To this end, 30 advance EFL learners were selected. A proficiency test was conducted to ensure if they were at the same level. Then, participants were asked to write a composition of 200-220 words. The data were analyzed. It had been revealed that the most frequent cohesive devices were reference cohesion followed by conjunction, lexical cohesion, ellipsis, and substitution. The most frequent cohesion errors committed by learners were also related to reference cohesion, conjunction, lexical cohesion, ellipsis, and substitution respectively. Furthermore, in this study some pedagogical implications had been suggested for language teachers regarding cohesion.
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van Schie, Janne J. M., and Job de Lange. "The Interplay of Cohesin and the Replisome at Processive and Stressed DNA Replication Forks." Cells 10, no. 12 (December 8, 2021): 3455. http://dx.doi.org/10.3390/cells10123455.
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The cohesin complex facilitates faithful chromosome segregation by pairing the sister chromatids after DNA replication until mitosis. In addition, cohesin contributes to proficient and error-free DNA replication. Replisome progression and establishment of sister chromatid cohesion are intimately intertwined processes. Here, we review how the key factors in DNA replication and cohesion establishment cooperate in unperturbed conditions and during DNA replication stress. We discuss the detailed molecular mechanisms of cohesin recruitment and the entrapment of replicated sister chromatids at the replisome, the subsequent stabilization of sister chromatid cohesion via SMC3 acetylation, as well as the role and regulation of cohesin in the response to DNA replication stress.
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Warren, Cheryl D., D. Mark Eckley, Marina S. Lee, Joseph S. Hanna, Adam Hughes, Brian Peyser, Chunfa Jie, Rafael Irizarry, and Forrest A. Spencer. "S-Phase Checkpoint Genes Safeguard High-Fidelity Sister Chromatid Cohesion." Molecular Biology of the Cell 15, no. 4 (April 2004): 1724–35. http://dx.doi.org/10.1091/mbc.e03-09-0637.
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Cohesion establishment and maintenance are carried out by proteins that modify the activity of Cohesin, an essential complex that holds sister chromatids together. Constituents of the replication fork, such as the DNA polymerase α-binding protein Ctf4, contribute to cohesion in ways that are poorly understood. To identify additional cohesion components, we analyzed a ctf4Δ synthetic lethal screen performed on microarrays. We focused on a subset of ctf4Δ-interacting genes with genetic instability of their own. Our analyses revealed that 17 previously studied genes are also necessary for the maintenance of robust association of sisters in metaphase. Among these were subunits of the MRX complex, which forms a molecular structure similar to Cohesin. Further investigation indicated that the MRX complex did not contribute to metaphase cohesion independent of Cohesin, although an additional role may be contributed by XRS2. In general, results from the screen indicated a sister chromatid cohesion role for a specific subset of genes that function in DNA replication and repair. This subset is particularly enriched for genes that support the S-phase checkpoint. We suggest that these genes promote and protect a chromatin environment conducive to robust cohesion.
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Watanabe, Yoshinori, and Tomoya S. Kitajima. "Shugoshin protects cohesin complexes at centromeres." Philosophical Transactions of the Royal Society B: Biological Sciences 360, no. 1455 (March 29, 2005): 515–21. http://dx.doi.org/10.1098/rstb.2004.1607.
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The different regulation of sister chromatid cohesion at centromeres and along chromosome arms is obvious during meiosis, because centromeric cohesion, but not arm cohesion, persists throughout anaphase of the first division. A protein required to protect centromeric cohesin Rec8 from separase cleavage has been identified and named shugoshin (or Sgo1) after shugoshin (‘guardian spirit’ in Japanese). It has become apparent that shugoshin shows marginal homology with Drosophila Mei-S332 and several uncharacterized proteins in other eukaryotic organisms. Because Mei-S332 is a protein previously shown to be required for centromeric cohesion in meiosis, it is now established that shugoshin represents a conserved protein family defined as a centromeric protector of Rec8 cohesin complexes in meiosis. The regional difference of sister chromatid cohesion is also observed during mitosis in vertebrates; the cohesion is much more robust at the centromere at metaphase, where it antagonizes the pulling force of spindle microtubules that attach the kinetochores from opposite poles. The human shugoshin homologue (hSgo1) is required to protect the centromeric localization of the mitotic cohesin, Scc1, until metaphase. Bub1 plays a crucial role in the localization of shugoshin to centromeres in both fission yeast and humans.
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Gong, Mingze, Sivar Azadi, Adrien Gans, Philippe Gondret, and Alban Sauret. "Erosion of a cohesive granular material by an impinging turbulent jet." EPJ Web of Conferences 249 (2021): 08011. http://dx.doi.org/10.1051/epjconf/202124908011.
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The erosion of a cohesive soil by an impinging turbulent jet is observed, for instance, during the landing of a spacecraft or involved in the so-called jet erosion test. To provide a quantitative understanding of this situation for cohesive soils, we perform experiments using a model cohesion controlled granular material that allows us to finely tune the cohesion between particles while keeping the other properties constant. We investigate the response of this cohesive granular bed when subjected to an impinging normal turbulent jet. We characterize experimentally the effects of the cohesion on the erosion threshold and the development of the crater. We demonstrate that the results can be rationalized by introducing a cohesive Shields number that accounts for the inter-particles cohesion force. The results of our experiments highlight the crucial role of cohesion in erosion processes.
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Atmowardoyo, Haryanto, and Geminastiti Sakkir. "Cohesion in Descriptive Discourse Written by The Sixth Semester Students of The English Department of FPBS IKIP Ujung Pandang." ARRUS Journal of Social Sciences and Humanities 3, no. 1 (April 11, 2023): 21–36. http://dx.doi.org/10.35877/soshum1659.
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This study of cohesion in descriptive discourse was written by students of the English Department of FPBS IKIP Ujung Pandang. This study describes the types of cohesion used in the students’ discourse and the degree of cohesive harmony of the discourse. It is drawn from the facts that this type of cohesion occurs very frequently in every student’s discourse. Cohesion in the students’ discourse does not function well as the foundation of coherence, drawn from the degree of cohesive harmony of the students’ discourse. As mentioned, the degree of cohesive harmony of the students’ discourse is low. The low degree of cohesive harmony expresses that the cohesion of the discourse does not function well as the foundation of coherence. It reflects that, in general, the students do not stay long enough on the similar things they are on about.
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Guacci, Vincent, and Douglas Koshland. "Cohesin-independent segregation of sister chromatids in budding yeast." Molecular Biology of the Cell 23, no. 4 (February 15, 2012): 729–39. http://dx.doi.org/10.1091/mbc.e11-08-0696.
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Cohesin generates cohesion between sister chromatids, which enables chromosomes to form bipolar attachments to the mitotic spindle and segregate. Cohesin also functions in chromosome condensation, transcriptional regulation, and DNA damage repair. Here we analyze the role of acetylation in modulating cohesin functions and how it affects budding yeast viability. Previous studies show that cohesion establishment requires Eco1p-mediated acetylation of the cohesin subunit Smc3p at residue K113. Smc3p acetylation was proposed to promote establishment by merely relieving Wpl1p inhibition because deletion of WPL1 bypasses the lethality of an ECO1 deletion (eco1Δ wpl1Δ). We find that little, if any, cohesion is established in eco1Δ wpl1Δ cells, indicating that Eco1p performs a function beyond antagonizing Wpl1p. Cohesion also fails to be established when SMC3 acetyl-mimics (K113Q or K112R,K113Q) are the sole functional SMC3s in cells. These results suggest that Smc3p acetylation levels affect establishment. It is remarkable that, despite their severe cohesion defect, eco1Δ wpl1Δ and smc3-K112R,K113Q strains are viable because a cohesin-independent mechanism enables bipolar attachment and segregation. This alternative mechanism is insufficient for smc3-K113Q strain viability. Smc3-K113Q is defective for condensation, whereas eco1Δ wpl1Δ and smc3-K112R,K113Q strains are competent for condensation. We suggest that Smc3p acetylation and Wpl1p antagonistically regulate cohesin's essential role in condensation.
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Bausch, Christoph, Seth Noone, Jill M. Henry, Karin Gaudenz, Brian Sanderson, Chris Seidel, and Jennifer L. Gerton. "Transcription Alters Chromosomal Locations of Cohesin in Saccharomyces cerevisiae." Molecular and Cellular Biology 27, no. 24 (October 8, 2007): 8522–32. http://dx.doi.org/10.1128/mcb.01007-07.
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ABSTRACT In eukaryotic cells, cohesion between sister chromatids allows chromosomes to biorient on the metaphase plate and holds them together until they separate into daughter cells during mitosis. Cohesion is mediated by the cohesin protein complex. Although the association of this complex with particular regions of the genome is highly reproducible, it is unclear what distinguishes a chromosomal region for cohesin association. Since one of the primary locations of cohesin is intergenic regions between converging transcription units, we explored the relationship between transcription and cohesin localization. Chromatin immunoprecipitation followed by hybridization to a microarray (ChIP chip) indicated that transcript elongation into cohesin association sites results in the local disassociation of cohesin. Once transcription is halted, cohesin can reassociate with its original sites, independent of DNA replication and the cohesin loading factor Scc2, although cohesin association with chromosomes in G2/M is not functional for cohesion. A computer program was developed to systematically identify differences between two ChIP chip data sets. Our results are consistent with a model for cohesin association in which (i) a portion of cohesin can be dynamically loaded and unloaded to accommodate transcription and (ii) the cohesin complex has preferences for features of chromatin that are a reflection of the local transcriptional status. Taken together, our results suggest that cohesion may be degraded by transcription.
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Carvalhal, Sara, Alexandra Tavares, Mariana B. Santos, Mihailo Mirkovic, and Raquel A. Oliveira. "A quantitative analysis of cohesin decay in mitotic fidelity." Journal of Cell Biology 217, no. 10 (July 12, 2018): 3343–53. http://dx.doi.org/10.1083/jcb.201801111.
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Sister chromatid cohesion mediated by cohesin is essential for mitotic fidelity. It counteracts spindle forces to prevent premature chromatid individualization and random genome segregation. However, it is unclear what effects a partial decline of cohesin may have on chromosome organization. In this study, we provide a quantitative analysis of cohesin decay by inducing acute removal of defined amounts of cohesin from metaphase-arrested chromosomes. We demonstrate that sister chromatid cohesion is very resistant to cohesin loss as chromatid disjunction is only observed when chromosomes lose >80% of bound cohesin. Removal close to this threshold leads to chromosomes that are still cohered but display compromised chromosome alignment and unstable spindle attachments. Partial cohesin decay leads to increased duration of mitosis and susceptibility to errors in chromosome segregation. We propose that high cohesin density ensures centromeric chromatin rigidity necessary to maintain a force balance with the mitotic spindle. Partial cohesin loss may lead to chromosome segregation errors even when sister chromatid cohesion is fulfilled.
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Rollins, Robert A., Maria Korom, Nathalie Aulner, Andrew Martens, and Dale Dorsett. "Drosophila Nipped-B Protein Supports Sister Chromatid Cohesion and Opposes the Stromalin/Scc3 Cohesion Factor To Facilitate Long-Range Activation of the cut Gene." Molecular and Cellular Biology 24, no. 8 (April 15, 2004): 3100–3111. http://dx.doi.org/10.1128/mcb.24.8.3100-3111.2004.
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ABSTRACT The Drosophila melanogaster Nipped-B protein facilitates transcriptional activation of the cut and Ultrabithorax genes by remote enhancers. Sequence homologues of Nipped-B, Scc2 of Saccharomyces cerevisiae, and Mis4 of Schizosaccharomyces pombe are required for sister chromatid cohesion during mitosis. The evolutionarily conserved Cohesin protein complex mediates sister chromatid cohesion, and Scc2 and Mis4 are needed for Cohesin to associate with chromosomes. Here, we show that Nipped-B is also required for sister chromatid cohesion but that, opposite to the effect of Nipped-B, the stromalin/Scc3 component of Cohesin inhibits long-range activation of cut. To explain these findings, we propose a model based on the chromatin domain boundary activities of Cohesin in which Nipped-B facilitates cut activation by alleviating Cohesin-mediated blocking of enhancer-promoter communication.
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Lee, Janice Y., Aki Hayashi-Hagihara, and Terry L. Orr-Weaver. "Roles and regulation of the Drosophila centromere cohesion protein MEI-S332 family." Philosophical Transactions of the Royal Society B: Biological Sciences 360, no. 1455 (March 29, 2005): 543–52. http://dx.doi.org/10.1098/rstb.2005.1619.
Full textAbstract:
In meiosis, a physical attachment, or cohesion, between the centromeres of the sister chromatids is retained until their separation at anaphase II. This cohesion is essential for ensuring accurate segregation of the sister chromatids in meiosis II and avoiding aneuploidy, a condition that can lead to prenatal lethality or birth defects. The Drosophila MEI-S332 protein localizes to centromeres when sister chromatids are attached in mitosis and meiosis, and it is required to maintain cohesion at the centromeres after cohesion along the sister chromatid arms is lost at the metaphase I/anaphase I transition. MEI-S332 is the founding member of a family of proteins that protect centromeric cohesion but whose members also affect kinetochore behaviour and spindle microtubule dynamics. We compare the Drosophila MEI-S332 family members, evaluate the role of MEI-S332 in mitosis and meiosis I, and discuss the regulation of localization of MEI-S332 to the centromere and its dissociation at anaphase. We analyse the relationship between MEI-S332 and cohesin, a protein complex that is also necessary for sister-chromatid cohesion in mitosis and meiosis. In mitosis, centromere localization of MEI-S332 is not dependent upon the cohesin complex, and cohesin retains its association with mitotic chromosomes even in the absence of MEI-S332.
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He, Zhongqing. "Cohesion in Academic Writing: A Comparison of Essays in English Written by L1 and L2 University Students." Theory and Practice in Language Studies 10, no. 7 (July 1, 2020): 761. http://dx.doi.org/10.17507/tpls.1007.06.
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Cohesion plays an important role in ensuring clarity, appropriateness, and comprehensibility in text. This study compares L1-Chinese and L1-English university students’ use of cohesion in English essays and examines the cohesive features in academic writing of L2 students from three perspectives: density of cohesion, distribution of cohesive devices, and distance of cohesive ties. Data consist of 126 student-produced essays in two corpora: 63 by L1-Chinese students from the TECCL corpus and 63 by L1-English students from the BAWE corpus. Findings indicate that L2 students have a lower density of cohesion in their academic writing. Their essays are marked by underuse of lexical cohesion and demonstrative reference, initial positioning of conjunctions, and heavy use of temporal conjunction. In addition, L2 students use significantly fewer immediate and remote cohesive ties, and the length of the material between ties is found to be inadequate compared to L1 students’ writing. The study has important implications for L2 writing pedagogy in China.
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Uru, Orvi Banja, Anselmus Sudirman, and Andhi Dwi Nugroho. "Exploring Cohesions in EFL Academic Writing: A State of the Art on the Study of Cohesions." Elsya : Journal of English Language Studies 3, no. 2 (June 27, 2021): 141–49. http://dx.doi.org/10.31849/elsya.v3i2.6730.
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Cohesion has become a crucial component of academic writing that promotes the semantic connection within phrases and sentences. The objectives of this literature review research are to identify different forms of cohesions and the most common form of cohesion in articles on EFL academic writing. This study extracted records from Google Scholar and Scopus databases and selected 20 studies in the last five years out of 700 on the use of cohesions in the writing of EFL students. The data was gathered by sorting similar messages, finding cohesions, clarifying cohesions, and counting the cohesions with the highest percentage. The research results show that the published articles containing cohesions represent the reference (35%), paired conjunctions (15%), reiteration (40%), and collocation (10%). The most common type of cohesion is reiteration, which is essential for comprehending what the authors mean in their published works. Cohesions in theoretical and practical grounds contribute to the explicitness of semantic components of words or phrases to generate the messages conveyed to readers.
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Cabrejas, Maribeth Mr. "Cohesive Devices on the Abstracts of Select Research Articles Presented in the International Academic Forum (AIFOR): A Discourse Analysis." British Journal of Multidisciplinary and Advanced Studies 3, no. 1 (October 27, 2022): 22–41. http://dx.doi.org/10.37745/bjmas.2022.0016.
Full textAbstract:
This linguistic research analysis investigates the cohesive devices found in the Abstract of select Asian Conference of Education 2019 research articles. This study also endeavors to disclose the contributions of the cohesive devices in the comprehensibility of the text. This corpus-based study utilizes qualitative descriptive research that specifically employs the evocative discourse analysis. It considers the use of Halliday and Hassan’s taxonomy on Cohesive devices as a basis for investigation. A total of twenty-eight (28) research abstracts are chosen from abstracts compiled in the program and abstract book of the Asian Conference on Education (ACE) presented during the International Academic Forum (IAFOR) held in Toshi Hotel, Tokyo, Japan last October 31 to November 3, 2019, as the main source of data. The data are analyzed using Halliday and Hasan’s taxonomy of cohesion which is divided into two aspects, grammatical and lexical cohesion. The result of the study reveals that researchers utilize two grammatical cohesions namely: reference and conjunctions in their research abstracts. The conjunctive features of the grammatical device found are additive, causal, adversative, and temporal. Moreover, the referential grammatical devices found are demonstrative, personal, article, and comparative. There is no usage of substitution and elliptical cohesion or ellipsis found. In terms of lexical cohesion, Reiteration devices such as repetition, synonymy, and antonymy are utilized by the researchers in their abstracts. There is no evidence of meronomy found in the analysis. Collocation devices are widely used in the abstract. In the analysis, the presence of the cohesive devices in the abstracts functions to keep track of the participants, organized in logical order the concepts in the abstract, and help in avoiding repetition and text redundancy which significantly contributes to the text comprehensibility of the research abstracts. Thus, the researcher designs and presents an English workbook for classroom use in which the drills provided focus on the correct usage of cohesive devices in any written discourse.
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Cabrejas, Maribeth Mr. "Cohesive Devices on the Abstracts of Select Research Articles Presented in the International Academic Forum (AIFOR): A Discourse Analysis." British Journal of Multidisciplinary and Advanced Studies 3, no. 1 (October 27, 2022): 22–41. http://dx.doi.org/10.37745/bjmas.2022.0017.
Full textAbstract:
This linguistic research analysis investigates the cohesive devices found in the Abstract of select Asian Conference of Education 2019 research articles. This study also endeavors to disclose the contributions of the cohesive devices in the comprehensibility of the text. This corpus-based study utilizes qualitative descriptive research that specifically employs the evocative discourse analysis. It considers the use of Halliday and Hassan’s taxonomy on Cohesive devices as a basis for investigation. A total of twenty-eight (28) research abstracts are chosen from abstracts compiled in the program and abstract book of the Asian Conference on Education (ACE) presented during the International Academic Forum (IAFOR) held in Toshi Hotel, Tokyo, Japan last October 31 to November 3, 2019, as the main source of data. The data are analyzed using Halliday and Hasan’s taxonomy of cohesion which is divided into two aspects, grammatical and lexical cohesion. The result of the study reveals that researchers utilize two grammatical cohesions namely: reference and conjunctions in their research abstracts. The conjunctive features of the grammatical device found are additive, causal, adversative, and temporal. Moreover, the referential grammatical devices found are demonstrative, personal, article, and comparative. There is no usage of substitution and elliptical cohesion or ellipsis found. In terms of lexical cohesion, Reiteration devices such as repetition, synonymy, and antonymy are utilized by the researchers in their abstracts. There is no evidence of meronomy found in the analysis. Collocation devices are widely used in the abstract. In the analysis, the presence of the cohesive devices in the abstracts functions to keep track of the participants, organized in logical order the concepts in the abstract, and help in avoiding repetition and text redundancy which significantly contributes to the text comprehensibility of the research abstracts. Thus, the researcher designs and presents an English workbook for classroom use in which the drills provided focus on the correct usage of cohesive devices in any written discourse.
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Wahyuni, Sri. "Analysis of the Use of Discourse Cohesion Means of Speech Texts of the Regional Government of Jambi Province." Indonesian Journal of Education Research (IJoER) 4, no. 6 (December 22, 2023): 155–59. http://dx.doi.org/10.37251/ijoer.v4i6.791.
Full textAbstract:
Purpose of the study: This research aims to describe the means of discourse cohesion and the use of discourse cohesion means in the speech text of the Jambi Province regional government at the plenary session on January 6 2016. The expected benefit of this research theoretically is that it can be used to develop theories about discourse, especially regarding the use of cohesion means in discourse speech text.
Methodology: The method used in this research is a qualitative method with descriptive research type. This research data is in the form of a means of cohesion contained in discourse. Data was obtained by reading the entire discourse of the speech text and marking the found means of cohesion and recording them.
Main Findings: The results of research in the speech text of the regional government of Jambi Province at the plenary session on January 6 2016 found that there were 9 types of cohesive devices, consisting of pronouns, substitutions, ellipsis, conjunctions, repetitions, synonyms, antonyms, hyponyms and collocations. It can be concluded that the most common means of cohesion are pronouns and conjunctions. So, from the results of the analysis that has been carried out, the text of the Jambi Province regional government's speech at the plenary session on January 6 2016 is included in the very cohesive category.
Novelty/Originality of this study: From the results of this research, it can be seen that there has been progress, namely that 9 means of cohesion were found and no non-cohesive means were found. Meanwhile, previous research only found 8 means of cohesion and found several uses of non-cohesive means of cohesion.
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McNicoll, François, Anne Kühnel, Uddipta Biswas, Kai Hempel, Gabriela Whelan, Gregor Eichele, and Rolf Jessberger. "Meiotic sex chromosome cohesion and autosomal synapsis are supported by Esco2." Life Science Alliance 3, no. 3 (February 12, 2020): e201900564. http://dx.doi.org/10.26508/lsa.201900564.
Full textAbstract:
In mitotic cells, establishment of sister chromatid cohesion requires acetylation of the cohesin subunit SMC3 (acSMC3) by ESCO1 and/or ESCO2. Meiotic cohesin plays additional but poorly understood roles in the formation of chromosome axial elements (AEs) and synaptonemal complexes. Here, we show that levels of ESCO2, acSMC3, and the pro-cohesion factor sororin increase on meiotic chromosomes as homologs synapse. These proteins are less abundant on the largely unsynapsed sex chromosomes, whose sister chromatid cohesion appears weaker throughout the meiotic prophase. Using three distinct conditional Esco2 knockout mouse strains, we demonstrate that ESCO2 is essential for male gametogenesis. Partial depletion of ESCO2 in prophase I spermatocytes delays chromosome synapsis and further weakens cohesion along sex chromosomes, which show extensive separation of AEs into single chromatids. Unsynapsed regions of autosomes are associated with the sex chromatin and also display split AEs. This study provides the first evidence for a specific role of ESCO2 in mammalian meiosis, identifies a particular ESCO2 dependence of sex chromosome cohesion and suggests support of autosomal synapsis by acSMC3-stabilized cohesion.
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Qu, Qianhui, Qian Zhang, Lu Yang, Yujue Chen, and Hong Liu. "SET binding to Sgo1 inhibits Sgo1–cohesin interactions and promotes chromosome segregation." Journal of Cell Biology 218, no. 8 (June 21, 2019): 2514–28. http://dx.doi.org/10.1083/jcb.201810096.
Full textAbstract:
At anaphase onset, Sgo1 function of cohesion protection must be disabled to allow timely chromosome segregation, but how this is achieved is not fully understood. Here, we show that SET, a known PP2A inhibitor, directly binds to a domain in Sgo1 in close proximity to the cohesin-binding motif. The Sgo1–cohesin binding can be disrupted by SET in a dose-dependent manner in vitro as well as by SET overexpression in cells, suggesting that SET is also an inhibitor to the Sgo1–cohesin binding. Furthermore, the SET binding–deficient Sgo1 mutant fully supports centromeric cohesion protection but delays chromosome segregation, suggesting that the SET–Sgo1 binding is required for timely chromosome segregation. Moreover, overexpression of SET WT, not the Sgo1 binding–deficient mutant, exacerbates the occurrence of cohesion fatigue in MG132-arrested cells. Conversely, SET depletion delays it. Thus, we propose that a major function of SET during mitosis is to disrupt the Sgo1–cohesin interaction, thereby promoting centromeric cohesion de-protection and timely chromosome segregation at anaphase onset.
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Suja, J. A., C. Antonio, A. Debec, and J. S. Rufas. "Phosphorylated proteins are involved in sister-chromatid arm cohesion during meiosis I." Journal of Cell Science 112, no. 17 (September 1, 1999): 2957–69. http://dx.doi.org/10.1242/jcs.112.17.2957.
Full textAbstract:
Sister-chromatid arm cohesion is lost during the metaphase I/anaphase I transition to allow homologue separation. To obtain needed information on this process we have analysed in grasshopper bivalents the sequential release of arm cohesion in relation to the behaviour of chromatid axes. Results show that sister axes are associated during early metaphase I but separate during late metaphase I leading to a concomitant change of chromosome structure that implies the loss of sister-kinetochore cohesion. Afterwards, homologues initiate their separation asynchronously depending on their size, and number and position of chiasmata. In all bivalents thin chromatin strands at the telomeres appeared as the last point of contact between sister chromatids. Additionally, we have analysed the participation of phosphoproteins recognised by the MPM-2 monoclonal antibody against mitotic phosphoproteins in arm cohesion in bivalents and two different kinds of univalents. Results show the absence of MPM-2 phosphoproteins at the interchromatid domain in mitotic chromosomes and meiotic univalents, but their presence in metaphase I bivalents. These phosphoproteins are lost at the onset of anaphase I. Taken together, these data have prompted us to propose a ‘working’ model for the release of arm cohesion during meiosis I. The model suggests that MPM-2 phosphoproteins may act as cohesive proteins associating sister axes. Their modification, once all bivalents are correctly aligned at the metaphase plate, would trigger a change of chromosome structure and the sequential release of sister-kinetochore, arm, and telomere cohesions.
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Henrikus, Sarah S., and Alessandro Costa. "Towards a Structural Mechanism for Sister Chromatid Cohesion Establishment at the Eukaryotic Replication Fork." Biology 10, no. 6 (May 26, 2021): 466. http://dx.doi.org/10.3390/biology10060466.
Full textAbstract:
Cohesion between replicated chromosomes is essential for chromatin dynamics and equal segregation of duplicated genetic material. In the G1 phase, the ring-shaped cohesin complex is loaded onto duplex DNA, enriching at replication start sites, or “origins”. During the same phase of the cell cycle, and also at the origin sites, two MCM helicases are loaded as symmetric double hexamers around duplex DNA. During the S phase, and through the action of replication factors, cohesin switches from encircling one parental duplex DNA to topologically enclosing the two duplicated DNA filaments, which are known as sister chromatids. Despite its vital importance, the structural mechanism leading to sister chromatid cohesion establishment at the replication fork is mostly elusive. Here we review the current understanding of the molecular interactions between the replication machinery and cohesin, which support sister chromatid cohesion establishment and cohesin function. In particular, we discuss how cryo-EM is shedding light on the mechanisms of DNA replication and cohesin loading processes. We further expound how frontier cryo-EM approaches, combined with biochemistry and single-molecule fluorescence assays, can lead to understanding the molecular basis of sister chromatid cohesion establishment at the replication fork.
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Sandra Putri Astariani, Putu. "The Analysis of Cohesive Devices Found in Good-Bye." Udayana Journal of Social Sciences and Humanities (UJoSSH) 4, no. 1 (February 29, 2020): 41. http://dx.doi.org/10.24843/ujossh.2020.v04.i01.p08.
Full textAbstract:
The basic definition of discourse is a language above sentences which is a cohesive, coherent, and functional. Cohesion and coherence are two vital elements constituting a discourse which are supported by the cohesive devices, i.e. reference, substitution, ellipsis, conjunctions, and lexical cohesion. This article discusses the cohesion and coherence of discourse through the identification of its cohesive devices. An anecdote entitled Good-Bye is selected due to its simplicity yet intriguing language, therefore the subliminal messages can be delivered and revealed. By using the qualitative approach and method, the results of the analysis, covering the cohesive devices within the text, can be comprehensively described. The analysis was carried based on the theory of functional grammar by MAK Halliday from his book Halliday's Introduction to Functional Grammar by MAK Halliday (revised by Christian MIM Matthiessen), about the cohesive devices. In addition to this one, the theory of cohesive devices from the book Cohesion in English by MAK Halliday and Ruqaiyah Hasan is used as a supporting theory. Within this anecdote, four out of five cohesive devices proposed by Halliday and Hasan were found. They covered the reference, ellipsis, conjunction, and lexical cohesion (reiteration and collocation). Unfortunately, substitution could not be found.