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Cell Nucleus: Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (Cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the Endoplasmic reticulum. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

The Nucleus

JoVE 10691

The nucleus is a membrane-bound organelle that contains a eukaryotic organism’s genetic instructions in the form of chromosomal DNA. This is distinct from the DNA in mitochondria or chloroplasts that carry out functions specific to those organelles. While some cells—such as red blood cells—do not have a nucleus, and others—such as skeletal muscle cells—have multiple nuclei, most eukaryotic cells have a single nucleus. The DNA in the nucleus is wrapped around proteins such as histones, creating a DNA-protein complex called chromatin. When cells are not dividing—that is, when they are in the interphase part of their cell cycle—the chromatin is organized diffusely. This allows easy access to the DNA during the transcription process when messenger RNA (mRNA) is synthesized based on the DNA code. When a eukaryotic cell is about to divide, the chromatin condenses tightly into distinct, linear chromosomes. Humans have 46 chromosomes in total. Chromatin is particularly concentrated in a region of the nucleus called the nucleolus. The nucleolus is important for the production of ribosomes, which translate mRNA into protein. In the nucleolus, ribosomal RNA is synthesized and combined with proteins to create ribosomal subunits, which later form functioning ribosomes in the cytoplasm of the cell. The interior of t

 Core: Cell Structure and Function

X-Inactivation

JoVE 11002

The human X chromosome contains over ten times the number of genes as in the Y chromosome. Since males have only one X chromosome, and females have two, one might expect females to produce twice as many of the proteins, with undesirable results.

Instead, in order to avoid this potential issue, female mammalian cells inactivate nearly all the genes in one of their X chromosomes during early embryonic development. In the nuclear envelope surrounding the cell nucleus, the inactivated X chromosome condenses into a small, dense ball called a Barr body. In this state, most of the X-linked genes are not accessible to transcription. In placental mammals, the inactivated X chromosome—maternal or paternal—is randomly determined (marsupials, however, preferentially inactivate the paternal X chromosome). X inactivation in one cell is also independent of X inactivation in other cells. Thus, about half the embryonic cells inactivate the maternal X copy; the remaining half inactivate the paternal copy, producing a mosaic. When these cells replicate, they produce cells with the same X chromosome inactivated. Notably, Barr bodies get reactivated in cells within the ovaries that become eggs. X inactivation accounts for the appearance of female tortoiseshell and calico cats. These cats are heterozygous for a gene with alleles for black fur and orange fur lo

 Core: Classical and Modern Genetics

The TUNEL Assay

JoVE 5651

One of the hallmarks of apoptosis is the nuclear DNA fragmentation by nucleases. These enzymes are activated by caspases, the family of proteins that execute the cell death program. TUNEL assay is a method that takes advantage of this feature to detect apoptotic cells. In this assay, an enzyme called terminal deoxynucleotidyl transferase catalyzes the addition of dUTP…

 Cell Biology

An Introduction to Developmental Genetics

JoVE 5325

Development is the complex process through which a single-celled embryo transforms into a multicellular organism. Developmental processes are guided by information encoded in an organism's DNA, and geneticists are trying to understand how this information leads to a fully formed organism.


This video reviews seminal research in the field of developmental biology, including the…

 Developmental Biology

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

1Centre d'Etudes Nucléaires Bordeaux Gradignan (CENBG), Université de Bordeaux, 2Centre d'Etudes Nucléaires Bordeaux Gradignan (CENBG), CNRS, 3Institut de Chimie de la Matière Condens é e de Bordeaux (ICMCB), CNRS, 4Institut de Chimie de la Matière Condens é e de Bordeaux (ICMCB), Université de Bordeaux

JoVE 55041

 Chemistry

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage

1Department of Biological Chemistry, School of Medicine, University of California, Irvine, 2Beckman Laser Institute and Medical Clinic, University of California, Irvine, 3Department of Developmental and Cell Biology, School of Biological Sciences, University of California, Irvine, 4Department of Biomedical Engineering and Surgery, University of California, Irvine

JoVE 56213

 Genetics

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

1Department of Thoracic and Cardiovascular Surgery and Inter-University Centre for Medical Technology Stuttgart-Tübingen (IZST), Eberhard Karls University, Tübingen, 2Department of Cell and Tissue Engineering, Fraunhofer Institute of Interfacial Engineering and Biotechnology (IGB) Stuttgart, Germany, 3Department for Medical Interfacial Engineering (IGVT), University of Stuttgart, Germany, 4Institute of Tissue Engineering and Regenerative Medicine, Julius-Maximillians University, Würzburg, Germany

JoVE 3977

 Bioengineering

Initial Evaluation of Antibody-conjugates Modified with Viral-derived Peptides for Increasing Cellular Accumulation and Improving Tumor Targeting

1Department of Nuclear Medicine and Radiobiology, Université de Sherbrooke, 2Sherbrooke Molecular Imaging Center (CIMS), Université de Sherbrooke, 3Sherbrooke Institute of Pharmacology

JoVE 55440

 Bioengineering

Photostimulation by Femtosecond Laser Activates Extracellular-signal-regulated Kinase (ERK) Signaling or Mitochondrial Events in Target Cells

1Department of Respiratory Medicine, Shanghai Sixth People's Hospital, School of Medicine, Shanghai Jiao Tong University, 2Ultrafast Laser Laboratory, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, 3School of Biomedical Engineering, Shanghai Jiao Tong University

JoVE 59661

 Biology

Microscopy-based Assays for High-throughput Screening of Host Factors Involved in Brucella Infection of Hela Cells

1Focal Area Infection Biology, Biozentrum, University of Basel, 2Centre d’Immunologie de Marseille-Luminy, Université de la Méditérannée UM2, INSERM U1104 CNRS UM7280, 3Departmento de Microbiologìa and Instituto de Salud Tropical, Universidad de Navarra, 4BioDataAnalysis GmbH

JoVE 54263

 Immunology and Infection

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

Preparation of Mitochondria from Ovarian Cancer Tissues and Control Ovarian Tissues for Quantitative Proteomics Analysis

1Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, 2Hunan Engineering Laboratory for Structural Biology and Drug Design, Xiangya Hospital, Central South University, 3State Local Joint Engineering Laboratory for Anticancer Drugs, Xiangya Hospital, Central South University, 4National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, 5Department of Obstetrics and Gynecology, Xiangya Hospital, Central South University

Video Coming Soon

JoVE 60435

 JoVE In-Press

3D Imaging of Soft-Tissue Samples using an X-ray Specific Staining Method and Nanoscopic Computed Tomography

1Department of Physics and Munich School of BioEngineering, Technical University of Munich, 2Department of Diagnostic and Interventional Radiology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich

Video Coming Soon

JoVE 60251

 JoVE In-Press

Immunohistochemical Staining of CD8 Protein in Tissue Sections from Patients with Tumors

1Department of Urology, the Seventh Affiliated Hospital, Sun Yat-sen University, 2Zhongshan School of Medicine, Sun Yat-sen University, 3Guanghua School of Stomatology, Sun Yat-sen University, 4Department of Pathology, the Seventh Affiliated Hospital, Sun Yat-sen University

Video Coming Soon

JoVE 57945

 JoVE In-Press

Laser-assisted Lentiviral Gene Delivery to Mouse Fertilized Eggs

1Neurobiology Laboratory, National Institute of Environmental Health Sciences, 2Comparative Medicine Branch, National Institute of Environmental Health Sciences, 3Reproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, 4Signal Transduction Laboratory, National Institute of Environmental Health Sciences

JoVE 58327

 Biology

Analysis of Epididymal Protein Synthesis and Secretion

1Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, 2Hunter Medical Research Institute, 3Department of Physiology, Turku Center for Disease Modeling, Institute of Biomedicine, University of Turku, 4School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle

JoVE 58308

 Developmental Biology
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