Relevant bibliographies by topics / CRITICAL GENES

Academic literature on the topic 'CRITICAL GENES'

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Published: 11 September 2023

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Journal articles on the topic "CRITICAL GENES"

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Epstein, Charles J. "Critical genes in a critical region." Nature 441, no. 7093 (May 31, 2006): 582–83. http://dx.doi.org/10.1038/441582a.

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Foster, Russell G., and Robert J. Lucas. "Clocks, criteria and critical genes." Nature Genetics 22, no. 3 (July 1999): 217–19. http://dx.doi.org/10.1038/10270.

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Kobayashi, Yohei, Zhanlei Ye, and Takao K. Hensch. "Clock Genes Control Cortical Critical Period Timing." Neuron 86, no. 1 (April 2015): 264–75. http://dx.doi.org/10.1016/j.neuron.2015.02.036.

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Mteyrek, Ali, Elisabeth Filipski, Catherine Guettier, Malgorzata Oklejewicz, Gijsbertus T. J. van der Horst, Alper Okyar, and Francis Lévi. "Critical cholangiocarcinogenesis control by cryptochrome clock genes." International Journal of Cancer 140, no. 11 (March 16, 2017): 2473–83. http://dx.doi.org/10.1002/ijc.30663.

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Evans, Kathryn L. "Minibrain genes and critical loci for down syndrome." Molecular Medicine Today 2, no. 12 (December 1996): 495. http://dx.doi.org/10.1016/s1357-4310(97)81450-5.

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Buchinsky, Farrel J., Craig S. Derkay, Suzanne M. Leal, Joseph Donfack, Garth D. Ehrlich, and J. Christopher Post. "Multicenter Initiative Seeking Critical Genes in Respiratory Papillomatosis." Laryngoscope 114, no. 2 (February 2004): 349–57. http://dx.doi.org/10.1097/00005537-200402000-00032.

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Dickson, David. "European patent directive in critical test over genes." Nature 372, no. 6504 (November 1994): 310. http://dx.doi.org/10.1038/372310a0.

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Galeev, Roman, Aurelie Baudet, Anders Kvist, Therese Törngren, and Jonas Larsson. "Cohesin genes are critical regulators of HSC renewal." Experimental Hematology 43, no. 9 (September 2015): S48. http://dx.doi.org/10.1016/j.exphem.2015.06.062.

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Hampton, Tracy. "Scientists Identify Genes Critical to Development of Leukemia." JAMA 315, no. 9 (March 1, 2016): 860. http://dx.doi.org/10.1001/jama.2016.1486.

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Roots, Kimberly. "Critical Mass: Inner space/genes/origins/environment/outer space." Science & Spirit 16, no. 4 (July 1, 2005): 15–24. http://dx.doi.org/10.3200/sspt.16.4.15-24.

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Dissertations / Theses on the topic "CRITICAL GENES"

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Strickson, Amanda J. "Analysis of expressed sequence tags mapping to the critical region of the 5q syndrome." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250497.

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Griffiths, Michael J. "Integrated approach to identifying genes critical in the response to malaria using gene expression profiling and disease association analyses." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491498.

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Nowak-Musial, Magdalena. "Evaluation of cellular processes and identification of candidate genes critical to corneal epithelial development." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54984/.

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The overall aim of this study was to determine factors and mechanisms that underlie the regulation of epithelial patterning and homeostasis during corneal development. Histological staining was performed in chick corneas, embryonic day (ED) 4 to 21, to evaluate changes in the overall epithelial cell morphology, in particular cell shape, cell size and the number of epithelial cell layers. Epithelial differentiation patterns were identified in frozen sections of chicken corneas after immunolocalisation of pan-cytokeratins (Pan-CK) and cytokeratin 3 (CK3). Proliferating Cell Nuclear Antigen (PCNA) and caspase 3 (active) immunolocalisation studies, as well as, TUNEL-labelling (Terminal deoxynucleotidyl transferase dUTP-biotin nick-end labelling) were performed to assess temporal and spatial localisation of cell proliferation and death in the developing corneal epithelium respectively. The expression of PCNA and CK3 were later confirmed by immunoblotting. Total RNA was isolated from epithelia at selected developmental time points and collected for microarray analysis. Gene expression profiles were analysed by appropriate mathematical methods. The sensitivity of arrays in producing data trends was validated by quantitative RT-PCR. Histological findings included changes in stratification an increase in the number of cell layers, change in cell morphology. In this study it was demonstrated that after becoming two layered by ED4, the epithelium underwent further stratification to form intermediate cell layers at about EDM. These changes were accompanied by changes in cell shape commencing at ED10. Cell proliferation appeared high throughout corneal development, with peak proliferation between ED12 and ED14 in the limbal, peripheral and central epithelium, respectively, thereafter the level of proliferation decreased. The above coincided with changes in epithelial morphology (stratification) and changes in expression of cytokeratin (CK) epithelial markers. The appearance of pan-CK labelling was first observed at ED10 and the presence of CK3 immunolabelling appeared in epithelial cells at ED12. TUNEL-labelling and caspase 3 (active) immunolocalisation demonstrated only few TUNEL-positive cells, mostly restricted in the limbal region of the corneal epithelium, in the mid and later developmental stages. Microarray analyses identified gene families and their members (including these involved in stem cell biology) likely to be relevant in the regulation of homeostasis during corneal epithelial development, as well as, differentially expressed genes that reveal changes in biological processes due to the change in time. RT-qPCR confirmed the differential expression patterns of seven genes of interest following analysis of microarray data. Patterns of cell proliferation and differentiation showed changes during the development of the corneal epithelium that reflect the interaction of a complex network of mitogenic, apoptotic and differentiation agents. The changes in gene expression profiles, detected by the microarray analyses, were consistent with the phenotypic changes in the developing chick corneal epithelium. The microarray data provided the first study to present a good overall picture of genes expression in the developing chick corneal epithelium.
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Serra, Barrionuevo Leticia. "Functional characterization of candidate tumor suppressor genes localized in the critical chromosomal region 13q14." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-65801.

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Schultz, Nikolaus. "Unraveling spermatogenesis: gene expression profiling with DNA microarrays reveals genes critical for germ cell development, fertilization and stem cell maintenance." [S.l. : s.n.], 2004. http://www.diss.fu-berlin.de/2004/178/index.html.

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Brown, Jacob D. "Expression profiling during ocular development identifies two NLZ genes with a critical role in fissure closure." Connect to Electronic Thesis (ProQuest) Connect to Electronic Thesis (CONTENTdm), 2008. http://worldcat.org/oclc/436300912/viewonline.

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Gatson, Na Tosha Na Chole. "Sex, pregnancy, and a great pair of genes critical mediators in the development and progression of CNS autoimmune injury /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195488191.

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Gatson, NaTosha Na Chole. "Sex, pregnancy, and a great pair of genes: critical mediators in the development and prograssion of CNS autoimmune injury." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1195488191.

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Yang, Steven. "Designing and characterizing artificial transcription factors targeting critical embryonic stem cell self-renewal and pluripotency genes in somatic cells." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1467691.

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Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 35-36).
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Wang, Yibing. "Study of cysteines in the stalk region of CD3 proteins : evolutionarily conserved residues critical for T cell development and function /." Connect to full text via ProQuest. Limited to UCD Anschutz Medical Campus, 2008.

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Thesis (Ph.D. in Immunology) -- University of Colorado Denver, 2008.
Typescript. Includes bibliographical references (leaves 138-153). Free to UCD Anschutz Medical Campus. Online version available via ProQuest Digital Dissertations;
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Books on the topic "CRITICAL GENES"

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Fly, Jones Beau, Scherpelz Martha S, and Thelen Judith N, eds. Cells and genes and me? Columbus, Ohio: Zaner-Bloser, 1992.

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Yan, Bin. Decoding critical genes of enterprises: The bionic laws for organizational longevity. Paramus, New Jersey: Homa & Sekey Books, 2013.

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Your genes, your health: A critical family guide that could save your life. New York: Oxford University Press, 2011.

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La Genesi: Con discussioni critiche. Firenze: Biblioteca scientifico-religiosa, 1985.

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1950-, Dixon Wheeler W., ed. Film genre 2000: New critical essays. Albany: State University of New York Press, 2000.

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1953-, Dunn David, ed. Harry Partch: An anthology of critical perspectives. Australia: Harwood Academic Publishers, 2000.

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Émile Bertaux tra storia dell'arte e meridionalismo: La genesi de L'art dans l'Italie méridionale. [Rome, Italy]: École française de Rome, 2007.

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1966-, Weiner Robert G., ed. Perspectives on the Grateful Dead: Critical writings. Westport, Conn: Greenwood Press, 1999.

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John, Knowles, and Brainard Paul, eds. Critica musica: Essays in honor of Paul Brainard. Australia: Gordon and Breach, 1996.

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Defining the sacred songs: Genre, tradition, and the post-critical interpretation of the Psalms. Sheffield, England: Sheffield Academic Press, 1999.

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Book chapters on the topic "CRITICAL GENES"

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Currie, Thomas E. "How the Dual Inheritance of Genes and Culture Shapes Behaviour: A Critical Review with a Focus on Human Culture and Behavioural Diversity." In Genes and Behaviour, 27–59. Chichester, UK: John Wiley & Sons, Ltd, 2019. http://dx.doi.org/10.1002/9781119313663.ch3.

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Progovac, Ljiljana. "Putting It All Together: The Language-Brain-Genes Loop." In A Critical Introduction to Language Evolution, 67–86. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-03235-7_4.

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Muppalaneni, Naresh Babu, K. Lalitha, and Sasikumar Gurumoorthy. "Identification of Critical Genes in Autism Disorder Using Centrality Measures." In Cognitive Science and Health Bioinformatics, 113–21. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-6653-5_11.

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Agarwal, Mohitesh Ch, Biswajit Jana, and Sriyankar Acharyya. "Identification of Disease Critical Genes in Preeclampsia Using Squirrel Search Algorithm." In Advances in Intelligent Systems and Computing, 289–97. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9927-9_29.

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Delihas, Nicholas. "Landscape of Long Noncoding RNA Genes, Pseudogenes, and Protein Genes in Segmental Duplications in the Critical Human Chromosomal Region 22q11.2." In RNA Technologies, 149–66. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44743-4_6.

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Domsch, Sebastian. "Critical genres." In Genres in the Internet, 221–38. Amsterdam: John Benjamins Publishing Company, 2009. http://dx.doi.org/10.1075/pbns.188.09dom.

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Brix, Nikko, and Kirsten Lauber. "Immune Checkpoint Inhibition and Radiotherapy in Head and Neck Squamous Cell Carcinoma: Synergisms and Resistance Mechanisms." In Critical Issues in Head and Neck Oncology, 11–21. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-23175-9_2.

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AbstractImmune checkpoint inhibition has emerged as an integral part of the standard-of-care for head and neck squamous cell carcinoma (HNSCC) in recurrent and/or metastatic stages. Clinical responses are impressive but remain limited to a minority of patients. Primary resistance of never-responders is considered to derive from host- and tumor-specific characteristics, the latter comprising tumor immune checkpoint activity, immune contexture, tumor mutational burden, neo-antigen load, and others. Secondary resistance of initially responding patients in addition, appears to be driven predominantly by irreversible T-cell exhaustion and therapy-induced selection of tumor cell clones with mutations in critical genes involved in the response to immune checkpoint inhibition. With particular focus on primary resistance against immune checkpoint inhibition, scientific interest of preclinical and clinical researchers currently aims at the development and evaluation of combined modality treatment approaches. Radiotherapy is a highly promising partner in this regard and represents a crucial treatment modality for patients with locally advanced HNSCC. Historically established as cytotoxic anti-cancer treatment, a growing body of evidence has shown additional locoregional and systemic immunomodulatory effects of radiotherapy. These are largely attributed to reprogramming of the tumor microenvironment driven by dying and senescent irradiated tumor and normal tissue cells and the concomitant cascade of danger signals, chemokines, and cytokines which stimulate immune cell recruitment and activation. Moreover, the irradiated state of tumor cells bears interesting analogy to the anti-viral state, since fragments of nuclear and mitochondrial DNA that are released into the cytosol can stimulate cytosolic nucleic acid sensors to produce intra-tumoral type I interferons which are essential to (re-)activate the cancer immunity cycle and (re-)invigorate systemic anti-tumor T-cell responses. Apart from these tumor adjuvanticity enhancing effects, several reports have also described increased tumor antigenicity upon radiotherapy originating from radiation-induced exposure of neo-antigens. Collectively, radiotherapy thus may serve as a means of personalized in situ vaccination which can synergize with immune checkpoint inhibition and may help to undermine primary resistance. First clinical experiences have shown that scheduling and dosing of such combined modality treatment regimens are challenging. Moreover, recent preclinical evidence suggests that particularly the role of radiation-induced cytokines and interferons appears to be complex in such combined modality settings due to their ambiguous effects on tumor and immune cells in the tumor microenvironment. The signaling cascades that orchestrate immune cell (re-)activation and cell fate decisions in irradiated tumor cells, including tumor cell survival, proliferation, and/or metastasis formation, are intimately interconnected and require further in-depth investigation.
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Zechel, C., U. Schleenbecker, A. Anders, M. Pfütz, and F. Anders. "Search for Genes Critical for the Early and/or Late Events in Carcinogenesis: Studies in Xiphophorus (Pisces, Teleostei)." In Haematology and Blood Transfusion / Hämatologie und Bluttransfusion, 366–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74621-5_64.

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Li, Chaolun, Minxiao Wang, Hao Wang, Li Zhou, Zhaoshan Zhong, Hao Chen, and Yan Sun. "Symbioses from Cold Seeps." In South China Sea Seeps, 89–113. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1494-4_6.

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AbstractEstablishing symbiosis between bacteria and invertebrates can significantly enhance energy transfer efficiency between them, which may aid in shaping the flourishing community in deep-sea chemosynthetic ecosystems, including cold seeps, hydrothermal vents, and organic falls. The symbionts utilize the chemical energy from reductive materials to fix carbon, and the hosts absorb the nutrients for growth through farming, milking, or both. Moreover, symbiosis can enhance the sustainability of both participants to survive in harsh conditions. However, the exact process and the regulatory network of symbiosis are still unknown. The cold seeps in the South China Sea offer natural laboratories to study the composition, ecological functions, and regulatory mechanisms of deep-sea symbioses. In this chapter, we focused on two dominant species, a deep-sea mussel Gigantidas platifrons and a squat lobster Shinkaia crosnieri, which represent endosymbiosis and episymbiosis, respectively, at Site F to summarize our understanding of deep-sea chemosymbiosis. We also discussed some promising avenues for future studies, such as deep-sea in situ experiments to show the exact responses of deep-sea organisms, culture-dependent experiments with genetic operations to validate the functions of critical genes, and microscale omics to elucidate the possible interactions at subcellular levels.
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Hazarika, Surovi, and Brian H. Annex. "Gene and Cell Therapy for Critical Limb Ischemia." In Critical Limb Ischemia, 491–501. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-31991-9_44.

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Conference papers on the topic "CRITICAL GENES"

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Dutta, Jahnabi, Surama Biswas, Souvik Saha, and Sriyankar Acharyya. "Identification of disease-critical genes causing preeclampsia: Meta-heuristic approaches." In 2015 IEEE UP Section Conference on Electrical Computer and Electronics (UPCON). IEEE, 2015. http://dx.doi.org/10.1109/upcon.2015.7456721.

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IBRAHIM, Raghad, Hussain K.K.AL-DULAIMY, and Izdehar M. JASIM. "DETERMINATION OF BIOFILM FORMATION GENES USING PCR TECHNIQUE FOR STAPH. SPP. ISOLATIONS FROM WOUND AND BURN INFECTIONS IN BAQUBA CITY." In IV.International Scientific Congress of Pure,Appliedand Technological Sciences. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress4-17.

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The bacteria Staphylococcus aureus has been discovered to be a major source of community and hospital-acquired infections. The production of ica-dependent biofilms is critical in the persistence of infections in hospitalized patients. Between November 2017 &April 2018, the current study was conducted at Teaching Baquba Hospital's Bacteriology Laboratory in Baquba City and the laboratory of microbiology and polymerase chain reaction (PCR )unit in the Biology Department / College of Science/ Diyala University (2018). Materials and methods: We obtained 13(17.3%) Staph.aureus isolates from 100 clinical specimens (burns, wounds, urine, and blood) after identified them. Following by employed Congo Red Agar(CRA) and tissue culture plate method (TCP)to detect Biofilm development in isolates, as well as a PCR assay and particular primers to determine the presence of the icaA &icaD genes. The results showed ica A/D were found in 69 % (9/13) of cases, icaA gene is present at 7 (53.8%) and the icaD gene at 2(15 .3%) in Staph.aureus isolates. CRA method found biofilm generation in 6 (46%) of thirteen Staph. aureus isolates, while TCP detected biofilm creation in 10 (76%) isolates. When phenotypic approaches compared to the detection of the icaA and icaD genes, only 5 (71%) of the icaA genes were found to be positive by TCP, while only 2 (1% ) of the icaD genes were found to be positive by TCP. In short: The findings show the significance of S. aureus' virulence factors in clinical samples for the icaA and icaD genes and the phenotypic biofilm formation variety. The creation of in vitro slime using the CRA approach is not necessarily consistent even when the icaA and icaD genes exist. Although certain isolates lack the genes icaA & icaD, the ability to generate biofilms highlights the importance of the further gene research, and the absence of the icaA and icaD genes, the capability from certain isolates to create biopolymes emphasises the need for continuous genetic study into icas caused by variations in the number of genes associated with biofilms. When comparing phenotypic techniques, TCP is still the best tool for the screening of biofilms. The aim of this research though is that the biofilm forming potential should be actually linked to the presence of icaA and icaD genes in S. aureus isolates
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Barman, Ranjan Kumar, Sagnik Sen, Anirban Mukhopadhyay, Ujjwal Maulik, and Santasabuj Das. "System biology approach to identify critical host genes for dengue infection." In 2020 International Conference on Computer, Electrical & Communication Engineering (ICCECE). IEEE, 2020. http://dx.doi.org/10.1109/iccece48148.2020.9223020.

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Celestini, Alessandro, Marco Cianfriglia, Enrico Mastrostefano, Alessandro Palma, Filippo Castiglione, and Paolo Tieri. "Critical nodes reveal peculiar features of human essential genes and protein interactome." In 2019 IEEE International Conference on Bioinformatics and Biomedicine (BIBM). IEEE, 2019. http://dx.doi.org/10.1109/bibm47256.2019.8983221.

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Williams, Justin, Beisi Xu, Daniel Putnam, and Xiang Chen. "Abstract 6576: DNA methylation reveals alternative promoter usage in genes critical to pediatric tumors." In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-6576.

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Jayakar, Sangeeta K., Olivier D. Loudig, Margaret Brandwein-Gensler, Ryung S. Kim, Michael B. Prystowsky, Jeffrey E. Segall, and Thomas J. Belbin. "Abstract 3158: Identifying novel genes critical to invasion in head and neck squamous cell carcinoma." In Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-3158.

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Herold, Marco Josef, Shinsuke Mizutani, Yexuan Deng, Ana Janic, Andrew Kueh, Martin Pal, Stephen Wilcox, Lin Tai, Gemma L. Kelly, and Andreas Strasser. "Abstract 3427: Finding critical cancer driving and cancer suppressing genes using functional genomics screeningin vivo." In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-3427.

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Ma, Yanxia, William M. Tahaney, Jing Qian, Jamal Hill, Yun Zhan, Abhijit Mazumdar, and Powel H. Brown. "Abstract 1303: PRTN3, RGCC and SLCO4C1 are critical SOX9-regulated genes that control TNBC growth." In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-1303.

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Jayakar, Sangeeta K., Olivier D. Loudig, Margaret Brandwein-Gensler, Kim S. Ryung, Michael B. Prystowsky, Jeffrey E. Segall, and Thomas J. Belbin. "Abstract C17: Identifying novel genes critical to invasion in head and neck squamous cell carcinoma." In Abstracts: AACR Special Conference on Tumor Invasion and Metastasis - January 20-23, 2013; San Diego, CA. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.tim2013-c17.

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Nakata, Asuka, Mai Yamauchi, Rui Yamaguchi, Takashi Kohno, Masao Nagasaki, Teppei Shimamura, Seiya Imoto, et al. "Abstract LB-99: EGF receptor tyrosine kinase defines critical prognostic genes of stage IA lung adenocarcinoma." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-lb-99.

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Reports on the topic "CRITICAL GENES"

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Belinsky, Steven. Critical Role for Aberrant CpG Island Methylation in the Evolution and Progression of Breast Cancer: Characterization of Known Genes and Identification of Novel Genes. Fort Belvoir, VA: Defense Technical Information Center, September 2001. http://dx.doi.org/10.21236/ada397409.

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Heifetz, Yael, and Michael Bender. Success and failure in insect fertilization and reproduction - the role of the female accessory glands. United States Department of Agriculture, December 2006. http://dx.doi.org/10.32747/2006.7695586.bard.

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The research problem. Understanding of insect reproduction has been critical to the design of insect pest control strategies including disruptions of mate-finding, courtship and sperm transfer by male insects. It is well known that males transfer proteins to females during mating that profoundly affect female reproductive physiology, but little is known about the molecular basis of female mating response and no attempts have yet been made to interfere with female post-mating responses that directly bear on the efficacy of fertilization. The female reproductive tract provides a crucial environment for the events of fertilization yet thus far those events and the role of the female tract in influencing them are poorly understood. For this project, we have chosen to focus on the lower reproductive tract because it is the site of two processes critical to reproduction: sperm management (storage, maintenance, and release from storage) and fertilization. E,fforts during this project period centered on the elucidation of mating responses in the female lower reproductive tract The central goals of this project were: 1. To identify mating-responsive genes in the female lower reproductive tract using DNA microarray technology. 2. In parallel, to identify mating-responsive genes in these tissues using proteomic assays (2D gels and LC-MS/MS techniques). 3. To integrate proteomic and genomic analyses of reproductive tract gene expression to identify significant genes for functional analysis. Our main achievements were: 1. Identification of mating-responsive genes in the female lower reproductive tract. We identified 539 mating-responsive genes using genomic and proteomic approaches. This analysis revealed a shift from gene silencing to gene activation soon after mating and a peak in differential gene expression at 6 hours post-mating. In addition, comparison of the two datasets revealed an expression pattern consistent with the model that important reproductive proteins are pre-programmed for synthesis prior to mating. This work was published in Mack et al. (2006). Validation experiments using real-time PCR techniques suggest that microarray assays provide a conservativestimate of the true transcriptional activity in reproductive tissues. 2.lntegration of proteomics and genomics data sets. We compared the expression profiles from DNA microarray data with the proteins identified in our proteomic experiments. Although comparing the two data sets poses analyical challenges, it provides a more complete view of gene expression as well as insights into how specific genes may be regulated. This work was published in Mack et al. (2006). 3. Development of primary reproductive tract cell cultures. We developed primary cell cultures of dispersed reproductive tract cell types and determined conditions for organ culture of the entire reproductive tract. This work will allow us to rapidly screen mating-responsive genes for a variety of reproductive-tract specifi c functions. Scientific and agricultural significance. Together, these studies have defined the genetic response to mating in a part of the female reproductive tract that is critical for successful fertllization and have identified alarge set of mating-responsive genes. This work is the first to combine both genomic and proteomic approaches in determining female mating response in these tissues and has provided important insights into insect reproductive behavior.
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Meir, Shimon, Michael S. Reid, Cai-Zhong Jiang, Amnon Lers, and Sonia Philosoph-Hadas. Molecular Studies of Postharvest Leaf and Flower Senescence. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7592657.bard.

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Original objectives: To understand the regulation of abscission by exploring the nature of changes of auxin-related gene expression in tomato (Lycopersicon esculatumMill) abscission zones (AZs) following organ removal, and by analyzing the function of these genes. Our specific goals were: 1) To complete the microarray analyses in tomato flower and leaf AZs, for identifying genes whose expression changes early in response to auxin depletion; 2) To examine, using virus-induced gene silencing (VIGS), the effect of silencing target genes on ethylene sensitivity and abscission competence of the leaf and flower AZs; 3) To isolate and characterize promoters from AZ-specific genes to be used in functional analysis; 4) To generate stable transgenic tomato plants with selected genes silenced with RNAi, under the control of an AZ-specific promoter, for further characterization of their abscission phenotypes. Background: Abscission, the separation of organs from the parent plant, results in postharvest quality loss in many ornamentals and other fresh produce. The process is initiated by changes in the auxin gradient across the AZ, and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the initiation of the abscission process, as the AZ becomes sensitized to ethylene. The present project was focused on elucidating these early molecular regulatory events, in order to gain a better control of the abscission process for agricultural manipulations. Major conclusions, solutions, achievements: Microarray analyses, using the Affymetrix Tomato GeneChip®, revealed changes in expression, occurring early in abscission, of many genes with possible regulatory functions. These included a range of auxin- and ethylene-related transcription factors (TFs), other TFs that are transiently induced just after flower removal, and a set of novel AZ-specific genes. We also identified four different defense-related genes, including: Cysteine-type endopeptidase, α- DOX1, WIN2, and SDF2, that are newly-associated with the late stage of the abscission process. This supports the activation of different defense responses and strategies at the late abscission stages, which may enable efficient protection of the exposed tissue toward different environmental stresses. To facilitate functional studies we implemented an efficient VIGS system in tomato, and isolated two abscission-specific promoters (pTAPG1 and pTAPG4) for gene silencing in stable transformation. Using the VIGS system we could demonstrate the importance of TAPGs in abscission of tomato leaf petioles, and evaluated the importance of more than 45 genes in abscission. Among them we identified few critical genes involved in leaf and flower abscission. These included: PTRP-F1, PRP, TKN4, KNOTTED-like homeobox TF, KD1, and KNOX-like homeodomain protein genes, the silencing of which caused a striking retardation of pedicel abscission, and ERF1, ERF4, Clavata-like3 protein, Sucrose transporter protein, and IAA10 genes, the silencing of which delayed petiole abscission. The importance of PRPand KD1 genes in abscission was confirmed also by antisense–silencing using pTAPG4. Experiments testing the effects of RNAi silencing of few other genes are still in progress, The analysis of the microarray results of flower and leaf AZs allowed us to establish a clear sequence of events occurring during acquisition of tissue sensitivity to ethylene, and to confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes in both AZs. Implication, both scientific and agricultural: Our studies had provided new insights into the regulation of the abscission process, and shaded light on the molecular mechanisms that drive the acquisition of abscission competence in the AZ. We pointed out some critical genes involved in regulation of abscission, and further expanded our knowledge of auxin-ethylene cross talk during the abscission process. This permits the development of novel techniques for manipulating abscission, and thereby improving the postharvest performance of ornamentals and other crops.
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Grumet, Rebecca, Rafael Perl-Treves, and Jack Staub. Ethylene Mediated Regulation of Cucumis Reproduction - from Sex Expression to Fruit Set. United States Department of Agriculture, February 2010. http://dx.doi.org/10.32747/2010.7696533.bard.

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Reproductive development is a critical determinant of agricultural yield. For species with unisexual flowers, floral secualdifferentation adds additional complexity, that can influenec productivity. The hormone ethylene has long, been known to play a primary role in sex determination in the Cucumis species cucumber (C. sativus) and melon (C. melo). Our objectives were to: (1) Determine critical sites of ethylene production and perception for sex determination; (2) Identify additional ethylene related genes associated with sex expression; and (3) Examine the role of environment ami prior fruit set on sex expression, pistillate flower maturation, and fruit set. We made progress in each of these areas. (1) Transgenic melon produced with the Arabidopsis dominant negative ethylene perception mutant gene, etrl-1, under the control of floral primordia targeted promoters [AP3 (petal and stamen) and CRC (carpel and nectary)], showed that ethylene perception by the stamen primordia, rather than carpel primordia, is critical for carpel development at the time of sex determination. Transgenic melons also were produced with the ethylene production enzyme gene. ACS, encoding l-aminocyclopropane-lcarboylate synthase, fused to the AP3 or CRC promoters. Consistent with the etr1-1 results, CRC::ACS did not increase femaleness; however, AP3::ACS reduced or eliminated male flower production. The effects of AP3:ACS were stronger than those of 35S::ACS plants, demonstratin g the importance of targeted expression, while avoiding disadvantages of constitutive ethylene production. (2) Linkage analysis coupled with SNP discovery was per formed on ethylene and floral development genes in cucumber populations segregating for the three major sex genes. A break-through towards cloning the cucumber M gene occurred when the melon andromonoecious gene (a), an ACS gene, was cloned in 2008. Both cucumber M and melon a suppress stamen development in pistillate flowers. We hypothesized that cucumber M could be orthologous to melon a, and found that mutations in CsACS2 co-segregated perfectly with the M gene. We also sought to identify miRNA molecules associated with sex determination. miRNA159, whose target in Arabidopsis is GAMYB[a transcription factor gene mediating response to10 gibberellin (GA)], was more highly expressed in young female buds than male. Since GA promotes maleness in cucumber, a micro RNA that counteracts GAMYB could promote femaleness. miRNA157, which in other plants targets transcription factors involved in flower development , was expressed in young male buds and mature flower anthers. (3) Gene expression profiling showed that ethylene-, senescence-, stress- and ubiquitin-related genes were up-regulated in senescing and inhibited fruits, while those undergoing successful fruit set up-regulated photosynthesis, respiration and metabolic genes. Melon plants can change sex expression in response to environmental conditions, leading to changes in yield potential. Unique melon lines with varying sex expression were developed and evaluated in the field in Hancock, Wisconsin . Environmental changes during the growing season influenced sex expression in highly inbred melon lines. Collectively these results are of significance for understanding regulation of sex expression. The fact that both cucumber sex loci identified so far (F and M) encode isoforms of the same ethylene synthesis enzyme, underscores the importance of ethylene as the main sex determining hormone in cucumber. The targeting studies give insight into developmental switch points and suggest a means to develop lines with earlier carpel-bearing flower production and fruit set. These results are of significance for understanding regulation of sex expression to facilitate shorter growing seasons and earlier time to market. Field results provide information for development of management strategies for commercial production of melon cultivars with different sex expression characteristics during fruit production.
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Anderson, Olin, and Gad Galili. Development of Assay Systems for Bioengineering Proteins that Affect Dough Quality and Wheat Utilization. United States Department of Agriculture, 1994. http://dx.doi.org/10.32747/1994.7568781.bard.

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The quality and utilization of wheat is largely dependent upon the exact physical/chemical properties of the doughs made from flour/water mixtures. Among the wheat seed components most correlated with dough visoelastic parameters are the high-molecular-weight (HMW) glutenin subunits whose disulfide cross-linked macropolymer is critical for dough functionality. We have used the tools of molecular biology, wheat transformation, heterologous expression of HMW-glutenin subunits in bacteria, and dough micro-mixing experiments to examine some of the molecular basis of HMW-glutenin functionality. In addition, we have developed sets of modified and synthetic gene constructs and transgenic wheat lines that will allow further examination of the role of the HMW-glutenins. Among the results from this work is evidence that the HMW-glutenin repeat domain is directly related to dough properties, the demonstration that interaction between subunits is dependent upon domain presence but not order, a novel understanding of the restrictions on intra-vs inter-chain disulfide bonds, the demonstration that HMW-glutenin genes can be transformed into wheat for simultaneously high expression of the transgene and suppression of the endogenous genes, and the construction of a set of modified HMW-glutenins capable of being epitope tagged for studying polypeptide subcellular processing and the fate of HMW-glutenins in dough mixing experiments.
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Bercovier, Herve, and Ronald P. Hedrick. Diagnostic, eco-epidemiology and control of KHV, a new viral pathogen of koi and common carp. United States Department of Agriculture, December 2007. http://dx.doi.org/10.32747/2007.7695593.bard.

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Original objectives and revisions-The proposed research included these original objectives: field validation of diagnostic tests (PCR), the development and evaluation of new sensitive tools (LC-PCR/TaqManPCR, antibody detection by ELISA) including their use to study the ecology and the epidemiology of KHV (virus distribution in the environment and native cyprinids) and the carrier status of fish exposed experimentally or naturally to KHV (sites of virus replication and potential persistence or latency). In the course of the study we completed the genome sequence of KHV and developed a DNA array to study the expression of KHV genes in different conditions. Background to the topics-Mass mortality of koi or common carp has been observed in Israel, USA, Europe and Asia. These outbreaks have reduced exports of koi from Israel and have created fear about production, import, and movements of koi and have raised concerns about potential impacts on native cyprinid populations in the U.S.A. Major conclusions-A suite of new diagnostic tools was developed that included 3 PCR assays for detection of KHV DNA in cell culture and fish tissues and an ELISA assay capable of detecting anti-KHV antibodies in the serum of koi and common carp. The TKPCR assay developed during the grant has become an internationally accepted gold standard for detection of viral DNA. Additionally, the ELISA developed for detecting serum anti-KHV antibodies is now in wide use as a major nonlethal screening tool for evaluating virus status of koi and common carp populations. Real time PCR assays have been able to detect viral DNA in the internal organs of survivors of natural and wild type vaccine exposures at 1 and 10³ genome equivalents at 7 months after exposure. In addition, vaccinated fish were able to transmit the virus to naive fish. Potential control utilizing hybrids of goldfish and common carp for production demonstrated they were considerably more resistant than pure common carp or koi to both KHV (CyHV-3). There was no evidence that goldfish or other tested endemic cyprinids species were susceptible to KHV. The complete genomic sequencing of 3 strains from Japan, the USA, and Israel revealed a 295 kbp genome containing a 22 kbp terminal direct repeat encoding clear gene homologs to other fish herpesviruses in the family Herpesviridae. The genome encodes156 unique protein-coding genes, eight of which are duplicated in the terminal repeat. Four to seven genes are fragmented and the loss of these genes may be associated with the high virulence of the virus. Viral gene expression was studies by a newly developed chip which has allowed verification of transcription of most all hypothetical genes (ORFs) as well as their kinetics. Implications, both scientific and agricultural- The results from this study have immediate application for the control and management of KHV. The proposal provides elements key to disease management with improved diagnostic tools. Studies on the ecology of the virus also provide insights into management of the virus at the farms that farmers will be able to apply immediately to reduce risks of infections. Lastly, critical issues that surround present procedures used to create “resistant fish” must be be resolved (e.g. carriers, risks, etc.). Currently stamping out may be effective in eradicating the disease. The emerging disease caused by KHV continues to spread. With the economic importance of koi and carp and the vast international movements of koi for the hobby, this disease has the potential for even further spread. The results from our studies form a critical component of a comprehensive program to curtail this emerging pathogen at the local, regional and international levels.
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Prusky, Dov, Nancy P. Keller, and Amir Sherman. global regulation of mycotoxin accumulation during pathogenicity of Penicillium expansum in postharvest fruits. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600012.bard.

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Background to the topic- Penicilliumas a postharvest pathogen and producer of the mycotoxin PAT. Penicilliumspp. are destructive phytopathogens, capable of causing decay in many deciduous fruits, during postharvest handling and storage; and the resulting losses can amount to 10% of the stored produce and the accumulation of large amounts of the mycotoxinpatulin. The overall goal of this proposal is to identify critical host and pathogen factors that modulate P. expansummycotoxin genes and pathways which are required for PAT production and virulence. Our preliminary results indicated that gluconic acid are strongly affecting patulin accumulation during colonization. P. expansumacidifies apple fruit tissue during colonization in part through secretion of gluconic acid (GLA). Several publications suggested that GLA accumulation is an essential factor in P. expansumpathogenicity. Furthermore, down regulation of GOX2 significantly reduced PAT accumulation and pathogenicity. PAT is a polyketide and its biosynthesis pathway includes a 15-gene cluster. LaeA is a global regulator of mycotoxin synthesis. It is now known that patulin synthesis might be subjected to LaeA and sometimes by environmental sensing global regulatory factors including the carbon catabolite repressor CreA as well as the pH regulator factor PacC and nitrogen regulator AreA. The mechanisms by which LaeA regulates patulin synthesis was not fully known and was part of our work. Furthermore, the regulatory system that controls gene expression in accordance with ambient pH was also included in our work. PacC protein is in an inactive conformation and is unable to bind to the promoter sites of the target genes; however, under alkaline growth conditions activated PacC acts as both an activator of alkaline-expressed genes and a repressor of acid-expressed genes. The aims of the project- This project aims to provide new insights on the roles of LaeA and PacC and their signaling pathways that lead to GLA and PAT biosynthesis and pathogenicity on the host. Specifically, our specific aims were: i) To elucidate the mechanism of pH-controlled regulation of GLA and PAT, and their contribution to pathogenesis of P. expansum. We are interested to understanding how pH and/or GLA impact/s under PacC regulation affect PAT production and pathogenesis. ii) To characterize the role of LaeA, the global regulator of mycotoxin production, and its effect on PAT and PacC activity. iii) To identify the signaling pathways leading to GLA and PAT synthesis. Using state- of-the-art RNAseq technologies, we will interrogate the transcriptomes of laeAand pacCmutants, to identify the common signaling pathways regulating synthesis of both GLA and PAT. Major conclusions, solutions, achievements- In our first Aim our results demonstrated that ammonia secreted at the leading edge of the fungal colony induced transcript activation of the global pH modulator PacC and PAT accumulation in the presence of GLA. We assessed these parameters by: (i) direct exogenous treatment of P. expansumgrowing on solid medium; (ii) direct exogenous treatment on colonized apple tissue; (iii) growth under self-ammonia production conditions with limited carbon; and (iv) analysis of the transcriptional response to ammonia of the PAT biosynthesis cluster. Ammonia induced PAT accumulation concurrently with the transcript activation of pacCand PAT biosynthesis cluster genes, indicating the regulatory effect of ammonia on pacCtranscript expression under acidic conditions. Transcriptomic analysis of pH regulated processes showed that important genes and BARD Report - Project 4773 Page 2 of 10 functionalities of P. expansumwere controlled by environmental pH. The differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Concerning the second and third Aims, we demonstrated that LaeA regulates several secondary metabolite genes, including the PAT gene cluster and concomitant PAT synthesis invitro. Virulence studies of ΔlaeAmutants of two geographically distant P. expansumisolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit ranging from no reduction for Ch-Pe-T01 strains in immature fruit to 15–25% reduction for both strains in mature fruit, with the ΔlaeAstrains of Is-Pe-21 always showing a greater loss in virulence. Results suggest the importance of LaeA regulation of PAT and other secondary metabolites on pathogenicity. Our work also characterized for the first time the role of sucrose, a key nutritional factor present in apple fruit, as a negative regulator of laeAexpression and consequent PAT production in vitro. This is the first report of sugar regulation of laeAexpression, suggesting that its expression may be subject to catabolite repression by CreA. Some, but not all of the 54 secondary metabolite backbone genes in the P. expansumgenome, including the PAT polyketide backbone gene, were found to be regulated by LaeA. Together, these findings enable for the first time a straight analysis of a host factor that potentially activates laeAand subsequent PAT synthesis.
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Barkan, Alice, and Zach Adam. The Role of Proteases in Regulating Gene Expression and Assembly Processes in the Chloroplast. United States Department of Agriculture, January 2003. http://dx.doi.org/10.32747/2003.7695852.bard.

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Chloroplasts house many biochemical processes that are essential for plant viability. Foremost, among these is photosynthesis, which requires the protein-rich thylakoid membrane system. The activation of chloroplast genes encoding thylakoid membrane proteins and the targeting and assembly of these proteins together with their nuclear-encoded partners are essential for the elaboration of the thylakoid membrane. Several nuclear-encoded proteins that regulate chloroplast gene expression and that mediate the targeting of proteins to the thylakoid membrane have been identified in recent years, and many more remain to be discovered. The abundance of such proteins is critical and is likely to be determined to a significant extent by their stability, which in turn, is influenced by chloroplast protease activities. The primary goal of this project was to link specific proteases to specific substrates, and in particular, to specific regulatory and assembly proteins. We proposed a two-pronged approach, involving genetic analysis of the consequences of the mutational loss of chloroplast proteases, and biochemical analysis of the degradation pathways of specific proteins that have been shown to control chloroplast gene expression. Our initial bioinformatic analysis of chloroplast proteases allowed us to identify the set of pro teases that is targeted to the chloroplast. We used that information to recover three Arabidopsis mutants with T - DNA insertions in specific chloroplast protease genes. We carried out the first analysis of the stability of a regulator of chloroplast gene expression (CRS2), and found that the protein is much less stable than are typical components of the photosynthetic apparatus. Genetic reagents and analytical methods were developed that have set the stage for a rapid advancement of our understanding of chloroplast proteolysis. The results obtained may be useful for manipulating the expression of transgenes in the chloroplast and for engineering plants whose photosynthetic activity is optimized under harsh environmental conditions.
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9

Shpigel, Nahum, Raul Barletta, Ilan Rosenshine, and Marcelo Chaffer. Identification and characterization of Mycobacterium paratuberculosis virulence genes expressed in vivo by negative selection. United States Department of Agriculture, January 2004. http://dx.doi.org/10.32747/2004.7696510.bard.

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Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of a severe inflammatory bowel disease (IBD) in ruminants, known as Johne’s disease or paratuberculosis. Johne’s disease is considered to be one of the most serious diseases affecting dairy cattle both in Israel and worldwide. Heavy economic losses are incurred by dairy farmers due to the severe effect of subclinical infection on milk production, fertility, lower disease resistance and early culling. Its influence in the United States alone is staggering, causing an estimated loss of $1.5 billion to the agriculture industry every year. Isolation of MAP from intestinal tissue and blood of Crohn's patients has lead to concern that it plays a potential pathogenic role in promoting human IDB including Crohn’s disease. There is great concern following the identification of the organism in animal products and shedding of the organism to the environment by subclinically infected animals. Little is known about the molecular basis for MAP virulence. The goal of the original proposed research was to identify MAP genes that are required for the critical stage of initial infection and colonization of ruminants’ intestine by MAP. We proposed to develop and use signature tag mutagenesis (STM) screen to find MAP genes that are specifically required for survival in ruminants upon experimental infection. This research projected was approved as one-year feasibility study to prove the ability of the research team to establish the animal model for mutant screening and alternative in-vitro cell systems. In Israel, neonatal goat kids were repeatedly inoculated with either one of the following organisms; MAP K-10 strain and three transposon mutants of K-10 which were produced and screened by the US PI. Six months after the commencement of inoculation we have necropsied the goats and taken multiple tissue samples from the jejunum, ileum and mesenteric lymph nodes. Both PCR and histopathology analysis indicated on efficient MAP colonization of all the inoculated animals. We have established several systems in the Israeli PI’s laboratory; these include using IS900 PCR for the identification of MAP and using HSP65-based PCR for the differentiation between MAV and MAP. We used Southern blot analysis for the differentiation among transposon mutants of K-10. In addition the Israeli PI has set up a panel of in-vitro screening systems for MAP mutants. These include assays to test adhesion, phagocytosis and survival of MAP to/within macrophages, assays that determine the rate of MAPinduced apoptosis of macrophages and MAP-induced NO production by macrophages, and assays testing the interference with T cell ã Interferon production and T cell proliferation by MAP infected macrophages (macrophage studies were done in BoMac and RAW cell lines, mouse peritoneal macrophages and bovine peripheral blood monocytes derived macrophages, respectively). All partners involved in this project feel that we are currently on track with this novel, highly challenging and ambitious research project. We have managed to establish the above described research systems that will clearly enable us to achieve the original proposed scientific objectives. We have proven ourselves as excellent collaborative groups with very high levels of complementary expertise. The Israeli groups were very fortunate to work with the US group and in a very short time period to master numerous techniques in the field of Mycobacterium research. The Israeli group has proven its ability to run this complicated animal model. This research, if continued, may elucidate new and basic aspects related to the pathogenesis MAP. In addition the work may identify new targets for vaccine and drug development. Considering the possibility that MAP might be a cause of human Crohn’s disease, better understanding of virulence mechanisms of this organism might also be of public health interest as well.
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Horwitz, Benjamin A., and Barbara Gillian Turgeon. Fungal Iron Acquisition, Oxidative Stress and Virulence in the Cochliobolus-maize Interaction. United States Department of Agriculture, March 2012. http://dx.doi.org/10.32747/2012.7709885.bard.

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Our project focused on genes for high affinity iron acquisition in Cochliobolus heterostrophus, a necrotrophic pathogen of maize, and their intertwined relationship to oxidative stress status and virulence of the fungus on the host. An intriguing question was why mutants lacking the nonribosomal peptide synthetase (NRPS) gene (NPS6) responsible for synthesis of the extracellular siderophore, coprogen, are sensitive to oxidative stress. Our overall objective was to understand the mechanistic connection between iron stress and oxidative stress as related to virulence of a plant pathogen to its host. The first objective was to examine the interface where small molecule peptide and reactive oxygen species (ROS) mechanisms overlap. The second objective was to determine if the molecular explanation for common function is common signal transduction pathways. These pathways, built around sensor kinases, response regulators, and transcription factors may link sequestering of iron, production of antioxidants, resistance to oxidative stress, and virulence. We tested these hypotheses by genetic manipulation of the pathogen, virulence assays on the host plant, and by following the expression of key fungal genes. An addition to the original program, made in the first year, was to develop, for fungi, a genetically encoded indicator of redox state based on the commercially available Gfp-based probe pHyper, designed for animal cell biology. We implemented several tools including a genetically encoded indicator of redox state, a procedure to grow iron-depleted plants, and constructed a number of new mutants in regulatory genes. Lack of the major Fe acquisition pathways results in an almost completely avirulent phenotype, showing how critical Fe acquisition is for the pathogen to cause disease. Mutants in conserved signaling pathways have normal ability to regulate NPS6 in response to Fe levels, as do mutants in Lae1 and Vel1, two master regulators of gene expression. Vel1 mutants are sensitive to oxidative stress, and the reason may be underexpression of a catalase gene. In nps6 mutants, CAT3 is also underexpressed, perhaps explaining the sensitivity to oxidative stress. We constructed a deletion mutant for the Fe sensor-regulator SreA and found that it is required for down regulation of NPS6 under Fe-replete conditions. Lack of SreA, though, did not make the fungus over-sensitive to ROS, though the mutant had a slow growth rate. This suggests that overproduction of siderophore under Fe-replete conditions is not very damaging. On the other hand, increasing Fe levels protected nps6 mutants from inhibition by ROS, implying that Fe-catalyzed Fenton reactions are not the main factor in its sensitivity to ROS. We have made some progress in understanding why siderophore mutants are sensitive to oxidative stress, and in doing so, defined some novel regulatory relationships. Catalase genes, which are not directly related to siderophore biosynthesis, are underexpressed in nps6 mutants, suggesting that the siderophore product (with or without bound Fe) may act as a signal. Siderophores, therefore, could be a target for intervention in the field, either by supplying an incorrect signal or blocking a signal normally provided during infection. We already know that nps6 mutants cause smaller lesions and have difficulty establishing invasive growth in the host. Lae1 and Vel1 are the first factors shown to regulate both super virulence conferred by T-toxin, and basic pathogenicity, due to unknown factors. The mutants are also altered in oxidative stress responses, key to success in the infection court, asexual and sexual development, essential for fungal dissemination in the field, aerial hyphal growth, and pigment biosynthesis, essential for survival in the field. Mutants in genes encoding NADPH oxidase (Nox) are compromised in development and virulence. Indeed the triple mutant, which should lack all Nox activity, was nearly avirulent. Again, gene expression experiments provided us with initial evidence that superoxide produced by the fungus may be most important as a signal. Blocking oxidant production by the pathogen may be a way to protect the plant host, in interactions with necrotrophs such as C. heterostrophus which seem to thrive in an oxidant environment.
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