CHAPTER 21 THE GENETIC BASIS OF DEVELOPMENT

Cleavage of frog embryos and a tadpole Cell division---differentiation---morphogenesis

apical meristems-perpetually embryonic regions

C. elegans a nematode worm; easily grown in lab; transparent body with few cell types; hermaphrodites; have a complete cell lineage

Cell lineage in C. elegans

Mus musculus-familiar genome is sequenced

Danio rerio-a zebra fish—easily breed in the lab; transparent embryos develop outside the mother’s body; early stages of development are quick

Arabidopsis - Quick growing wall cress plant 8-10 weeks life cycle; each flower makes eggs and sperm; its genome has been sequenced; cells will take up DNA; small genome

Cloning of a carrot Many somatic cells apical meristems of a plant remain totipotent and thus a clone can be produced from one of them.

Nuclear transplantation Undifferentiated cell Nuclear transplantation

semistarvation

Dolly and her surrogate mother

Cloned from a kidney cell from a cadaver

Adult Stem Cells Hematopoietic stem cells give rise to all the types of blood cells: red blood cells, B lymphocytes, T lymphocytes, natural killer cells, neutrophils, basophils, eosinophils, monocytes, macrophages, and platelets. Bone marrow stromal cells (mesenchymal stem cells) give rise to a variety of cell types: bone cells (osteocytes), cartilage cells (chondrocytes), fat cells (adipocytes), and other kinds of connective tissue cells such as those in tendons. neural stem cells in the brain give rise to its three major cell types: nerve cells (neurons) and two categories of non-neuronal cells—astrocytes and oligodendrocytes.

Epithelial stem cells in the lining of the digestive tract occur in deep crypts and give rise to several cell types: absorptive cells, goblet cells, and enteroendocrine cells. Skin stem cells occur in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells give rise to keratinocytes, which migrate to the surface of the skin and form a protective layer. The follicular stem cells can give rise to both the hair follicle and to the epidermis.

Adult Stem Cells Embryonic Stem Cells Cancers: Brain Cancer NONE Retinoblastoma Ovarian Cancer Skin Cancer: Merkel Cell Carcinoma Testicular Cancer Tumors abdominal organs Lymphoma Non-Hodgkin’s lymphoma Hodgkin’s Lymphoma Acute Lymphoblastic Leukemia Acute Myelogenous Leukemia Chronic Myelogenous Leukemia Juvenile Myelomonocytic Leukemia Chronic Myelomonocytic Leukemia Cancer of the lymph nodes: Angioimmunoblastic Lymphadenopathy Multiple Myeloma Myelodysplasia Breast Cancer Neuroblastoma Renal Cell Carcinoma Various Solid Tumors Soft Tissue Sarcoma Ewing’s Sarcoma Waldenstrom’s macroglobulinemia Hemophagocytic lymphohistiocytosis POEMS syndrome Myelofibrosis Auto-Immune Diseases Sjogren’s Syndrome Systemic Lupus Myasthenia Autoimmune Cytopenia Scleromyxedema Scleroderma Crohn’s Disease Behcet’s Disease Rheumatoid Arthritis Juvenile Arthritis Multiple Sclerosis Polychondritis Systemic Vasculitis Alopecia Universalis Buerger’s Disease Cardiovascular Acute Heart Damage Chronic Coronary Artery Disease Ocular Corneal regeneration Immunodeficiencies Severe Combined Immunodeficiency Syndrome X-linked Lymphoproliferative Syndrome X-linked Hyper immunoglobulin M Syndrome Neural Degenerative Diseases and Injuries Parkinson’s Disease Spinal Cord Injury Stroke Damage Anemias and Other Blood Conditions Sickle Cell Anemia Sideroblastic Anemia Aplastic Anemia Red Cell Aplasia Amegakaryocytic Thrombocytopenia Thalassemia Primary Amyloidosis Diamond Blackfan Anemia Fanconi’s Anemia Chronic Epstein-Barr Infection Wounds and Injuries Limb Gangrene Surface Wound Healing Jawbone Replacement Skull Bone Repair Other Metabolic Disorders Hurler’s Syndrome Osteogenesis Imperfecta Krabbe Leukodystrophy Osteopetrosis Cerebral X-Linked Adrenoleukodystrophy Liver Disease Chronic Liver Failure Liver Cirrhosis Bladder Disease End-Stage Bladder Disease

Determination-expression of a master control gene myoD-sets the fate of a cell causing a specific differentiation-expression of genes that encode tissue-specific proteins

cytoplasmic determinants maternal substances in the cytoplasm of the egg that regulate gene expression

Induction-movement of signal molecules from nearby cells

Key developmental events in the life cycle of a fruit fly Pattern formation-tissues and organs are all in their characteristic places molecular clues that control pattern formation are called positional information tell a cell its location relative to the body axes and to neighboring cells

embryonic lethals-mutations affecting a fundamental process in an embryo maternal effects genes-when mutant in the mother, results in a mutant phenotype egg-polarity genes-maternal effect genes that control the orientation of the egg bicoid gene-sets the anterior end of the fly morphogens-substances whose gradients establish an embryo’s axes and other major factors

homeotic genes-the master regulatory genes that set the anatomical identity of the segments determine what appendages will be produced on a segment

Homologous genes that affect pattern formation in a fruit fly and a mouse homeobox-180-nucleotide sequence found in the homeotic genes of many species each of these boxes contains a homeobox

Homeobox-containing genes as switches

Apoptosis

Miniature front legs

Missing eye

Pudgy

Ruby eye

Stargazer

Ulnaless

Ulnaless

Nude Mouse