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Poly A: A group of adenine ribonucleotides in which the phosphate residues of each adenine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.

Complementary DNA

JoVE 10818

Only genes that are transcribed into messenger RNA (mRNA) are active, or expressed. Scientists can, therefore, extract the mRNA from cells to study gene expression in different cells and tissues. The scientist converts mRNA into complementary DNA (cDNA) via reverse transcription. Because mRNA does not contain introns (non-coding regions) and other regulatory sequences, cDNA—unlike genomic DNA—also allows researchers to directly determine the amino acid sequence of the peptide encoded by the gene. cDNA can be generated by several methods, but a common way is to first extract total RNA from cells, and then isolate the mRNA from the more predominant types—transfer RNA (tRNA) and ribosomal (rRNA). Mature eukaryotic mRNA has a poly(A) tail—a string of adenine nucleotides—added to its 3’ end, while other types of RNA do not. Therefore, a string of thymine nucleotides (oligo-dTs) can be attached to a substrate such as a column or magnetic beads, to specifically base-pair with the poly(A) tails of mRNA. While mRNA with a poly(A) tail is captured, the other types of RNA are washed away. Next, reverse transcriptase—a DNA polymerase enzyme from retroviruses—is used to generate cDNA from the mRNA. Since, like most DNA polymerases, reverse transcriptase can add nucleotides only to the 3’ end of a chain, a pol

 Core: Biotechnology

pre-mRNA processing

JoVE 11003

In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or pre-mRNA, to distinguish it from mature mRNA.

Once about 20-40 ribonucleotides have been joined together by RNA polymerase, a group of enzymes adds a “cap” to the 5’ end of the growing transcript. In this process, a 5’ phosphate is replaced by modified guanosine that has a methyl group attached to it. This 5’ cap helps the cell distinguish mRNA from other types of RNA in the cell and plays a role in subsequent translation. During or shortly after transcription, a large complex called the spliceosome cuts out various parts of the pre-mRNA transcript, rejoining the remaining sequences. RNA sequences that remain in the transcript are called “exons” (expressed sequences) while portions removed are called “introns”. Interestingly, a single RNA segment can be an exon in one cell type and an intron in another. Similarly, a single cell can contain multiple variants of a gene transcript that has been alternatively spliced, enabling the production of multiple proteins from a single gene. When transcription is completed, an enzyme adds approximately 30-200 adenine nucleotides to the 3’ end of the pre-mRNA molecule. This poly-A tail protects the mRNA fr

 Core: Gene Expression

The Central Dogma

JoVE 10798

The central dogma of biology states that information encoded in the DNA is transferred to messenger RNA (mRNA), which then directs the synthesis of protein. The set of instructions that enable the mRNA nucleotide sequence to be decoded into amino acids is called the genetic code. The universal nature of this genetic code has spurred advances in scientific research, agriculture, and medicine. In the early 1900s, scientists discovered that DNA stores all the information needed for cellular functions and that proteins perform most of these functions. However, the mechanisms of converting genetic information into functional proteins remained unknown for many years. Initially, it was believed that a single gene is directly converted into its encoded protein. Two crucial discoveries in eukaryotic cells challenged this theory: First, protein production does not take place in the nucleus. Second, DNA is not present outside the nucleus. These findings sparked the search for an intermediary molecule that connects DNA with protein production. This intermediary molecule, found in both the nucleus and the cytoplasm, and associated with protein production, is RNA. During transcription, RNA is synthesized in the nucleus, using DNA as a template. The newly-synthesized RNA is similar in sequence to the DNA strand, except thymidine in DNA is replaced by uracil i

 Core: Gene Expression

RNA-Seq

JoVE 5548

Among different methods to evaluate gene expression, the high-throughput sequencing of RNA, or RNA-seq. is particularly attractive, as it can be performed and analyzed without relying on prior available genomic information. During RNA-seq, RNA isolated from samples of interest is used to generate a DNA library, which is then amplified and sequenced. Ultimately, RNA-seq can …

 Genetics

Capture and Identification of RNA-binding Proteins by Using Click Chemistry-assisted RNA-interactome Capture (CARIC) Strategy

1College of Chemistry and Molecular Engineering, Peking University, 2Beijing National Laboratory for Molecular Sciences, Peking University, 3Peking-Tsinghua Center for Life Sciences, Peking University, 4Synthetic and Functional Biomolecules Center, Peking University, 5Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Peking University

JoVE 58580

 Biochemistry

Microarray-based Identification of Individual HERV Loci Expression: Application to Biomarker Discovery in Prostate Cancer

1Joint Unit Hospices de Lyon-bioMérieux, 2Medical Diagnostic Discovery Department, BioMérieux, 3Department of Pathology and Cytology, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, 4Medical Faculty, Lyon 1 University, 5Data and Knowledge Laboratory, BioMérieux, 6Department of Biochemistry and Molecular Biology, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, 7Department of Urology, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon

JoVE 50713

 Medicine

Gene Expression Analysis of Endothelial Cells Exposed to Shear Stress Using Multiple Parallel-plate Flow Chambers

1Institute of Medical Science, University of Toronto, 2Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 3Department of Laboratory Medicine and Pathobiology, University of Toronto, 4Department of Medicine, University of Toronto

JoVE 58478

 Bioengineering

Detection of a Circulating MicroRNA Custom Panel in Patients with Metastatic Colorectal Cancer

1Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 2Department of Medical Oncology, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 3Unit of Biostatistics and Clinical Trials, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS

JoVE 58615

 Cancer Research

Molecular Analysis of Endothelial-mesenchymal Transition Induced by Transforming Growth Factor-β Signaling

1David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 2Department of Respiratory Medicine, Graduate School of Medicine, The University of Tokyo, 3Hastings Center for Pulmonary Research, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, 4Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo

JoVE 57577

 Biology

Sample Preparation for Mass Spectrometry-based Identification of RNA-binding Regions

1Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, 2Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 3Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, 4Graduate Group in Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine

JoVE 56004

 Biochemistry

Detection of microRNA Expression in Peritoneal Membrane of Rats Using Quantitative Real-time PCR

1Division of Nephrology, First Department of Integrated Medicine, Saitama Medical Center, Jichi Medical University, 2Division of Nephrology, Department of Internal Medicine, Jichi Medical University, 3Department of Medical Physiology, Meiji Pharmaceutical University

JoVE 55505

 Genetics

Genome-wide Analysis of HDAC Inhibitor-mediated Modulation of microRNAs and mRNAs in B Cells Induced to Undergo Class-switch DNA Recombination and Plasma Cell Differentiation

1Department of Microbiology, Immunology and Molecular Genetics, University of Texas Long School of Medicine at San Antonio, 2Xiangya School of Medicine, Cental South University, 3Greehey Children’s Cancer Research Institute, University of Texas Long School of Medicine at San Antonio

JoVE 55135

 Immunology and Infection

Measurement of Differentially Methylated INS DNA Species in Human Serum Samples as a Biomarker of Islet β Cell Death

1Department of Pediatrics, IU Center for Diabetes and Metabolic Disease, Indiana University School of Medicine, 2Department of Pediartics, Omaha Children's Hospital and Medical Center, University of Nebraska Medical Center, 3Departments of Biochemistry and Molecular Biology, Medicine, and Cellular and Integrative Physiology, IU Center for Diabetes and Metabolic Disease, Indiana University School of Medicine, 4Indiana Biosciences Research Institute

JoVE 54838

 Genetics
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