Biology 122 Genes and Development Development of organisms

Fig Cleavage in a frog embryo

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. C M G 2 interphase mitosis cytokinesis G2G2 S G1G1 M C Mitosis Adult Cell Cycle S Mitosis Active Cell Cycle of Early Frog Blastomere Active C M S S M Cdk Inactive a.b. Cdk / G1 cyclin Cdk / G2 cyclin Cdk / S cyclin G1G1 DNA Synthesis Cyclin Degradation Cyclin Synthesis Cdk / cyclin DNA Synthesis In blastomeres, cyclin mRNA came from unfertilized eggs. When cyclin protein is degraded, the cell exits mitosis

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nematode Lineage Map a. b. Egg Pharynx Cuticle-making cells Egg Sperm Adult Nematode Vulva Gonad Nervous system Pharynx Intestine Cuticle Intestine Egg and sperm line Nervous system Vulva Lineage map of C. elegans

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Donor No donor Normal Head Recipient Before Overt Differentiation Recipient After Overt Differentiation Tail cells develop into head cells in head Tail cells develop into tail cells in head Tail cells are transplanted to head Tail cells are transplanted to head Not Determined (early development) Determined (later development) Tail Test for determination

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. MEIOSIS a. n 2n b. FERTILIZATION 50 µm b: © J. Richard Whittaker, used by permission Adult tunicate (diploid) 2n Larva (diploid) 2n Embryo (diploid) 2n Pigment granules Sperm (haploid) n Egg (haploid) n Tunicate development-muscle determination

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b.c. 2 1 Notochord (Not) Anterior Posterior AnteriorPosterior a. 21 FGF signaling Sagittal sectionLongitudinal section Dorsal nerve cord (NC) Mesenchymal cells (Mes) 32-Cell Stage64-Cell Stage Anterior Posterior Ventral endoderm (En) Tail muscle cells (Mus) Specification of cell fate in tunicates

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a.a. Mesenchyme Muscle Notochord FGF Signal received Cell TypesSecond StepFirst Step Macho-1 inherited? Yes No Nerve cord Yes No Yes No Cell fate specification in tunicates

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b.b. FGF Receptor No FGF FGF Receptor No FGF FGF Receptor Cell membrane Ras/MAPK Pathway T-Ets No Macho-1 T-Ets No Macho-1 T-EtsMacho-1 Suppression of muscle genes and activation of mesenchyme genes Transcription of muscle genes Transcription of notochord genes Nerve cord Precursor Cells Notochord Precursor Cells Muscle Precursor Cells Mesenchyme Precursor Cells a.a. P P Suppression of notochord genes and activation of nerve cord genes Cell membrane Mesenchyme Muscle Notochord FGF Signal received Cell TypesSecond StepFirst Step Macho-1 inherited? Yes No Nerve cord Yes No Yes No FGF

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a.b. Egg SpermBlastocystEmbryo Embryonic stem cells (ES cells) are isolated from the inner cell mass Embryonic stem cell culture Once sperm cell and egg cell have joined, cell cleavage produces a blastocyst. The inner cell mass of the blastocyst develops into the human embryo. Inner cell mass b: © University of Wisconsin-Madison 500 µm Isolation of embryonic stem cells

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © APTV/AP Photo Embryo Egg cell is extracted. Development ImplantationBirth of Clone PreparationCell Fusion Cell Division Mammary cell is extracted and grown in nutrient-deficient solution that arrests the cell cycle. Nucleus containing source DNA Nucleus is removed fro egg cell with a micropipette. Mammary cell is inserted inside covering of egg cell. Electric shock fuses cell membranes and triggers cell division. Embryo begins to develop in vitro. Embryo is implanted into surrogate mother. After a five-month pregnancy, a lamb genetically identical to the sheep from which the mammary cell was extracted is born. Growth to Adulthood Sheep cloning-Dolly

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Somatic cells Oocyte Somatic cells Blastocyst Fusion Culture Somatic cells ES cells Nuclear Transfer Pluripotent stem cells Defined factors Germ cells Some adult stem cells Reprogramming Adult cell nuclei

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Early embryo Blastocyst The skin cell nucleus is inserted into the enucleated human egg cell. Cell cleavage occurs as the embryo begins to develop in vitro. The embryo reaches the blastocyst stage. Inner cell mass ES cells Embryonic stem cells (ES cells) are extracted and grown in culture. The stem cells are developed into healthy pancreatic islet cells needed by the patient. The healthy tissue is injected or transplanted into the diabetic patient. Healthy pancreatic islet cells Therapeutic cloning Diabetic patient Diabetic patient The nucleus from a skin cell of a diabetic patient is removed. Potential therapeutic cloning of cells for therapy in humans

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hatching larva c. b. AnteriorPosterior Oocyte Fertilized egg Nucleus a. d. e. Three larval stages Syncytial blastoderm Cellular blastoderm Segmented embryo prior to hatching Metamorphosis Abdomen Thorax Head Movement of maternal mRNA Follicle cells Nurse cells Nuclei line up along surface, and membranes grow between them to form a cellular blastoderm. Drosophila (fruit fly) development Oocyte/egg Larval instars Blastoderms Pupa Adult

Fig a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Establishing the Polarity of the Embryo Fertilization of the egg triggers the production of Bicoid protein from maternal RN A in the egg. The Bicoid protein diffuses through the egg, forming a gradient. This gradient determines the polarity of the embryo, with the head and thorax developing in the zone of high concentration (green fluorescent dye in antibodies that bind bicoid protein allows visualization of the gradient). 500 µm © Steve Paddock and Sean Carroll

Fig b Setting the Stage for Segmentation About 21/2 hours after fertilization, Bicoid protein turns on a series of brief signals from so-called gap genes. The gap proteins act to divide the embryo into large blocks. In this photo, fluorescent dyes in antibodies that bind to the gap proteins Krüppel (orange) and Hunchback (green) make the blocks visible; the region of overlap is yellow. 500 µm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Jim Langeland, Steve Paddock and Sean Carroll

Fig c Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Laying Down the Fundamental Regions About 0.5 hr later, the gap genes switch on the “pair-rule” genes, which are each expressed in seven stripes. This is shown for the pair-rule gene hairy. Some pair-rule genes are only required for even-numbered segments while others are only required for odd numbered segments. 500 µm © Jim Langeland, Steve Paddock and Sean Carroll

Fig d Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Forming the Segments H T A The final stage of segmentation occurs when a “segment- polarity” gene called engrailed divides each of the seven regions into halves, producing 14 narrow compartments. Each compartment corresponds to one segment of the future body. There are three head segments (H, bottom right), three thoracic segments (T, upper right), and eight abdominal segments (A, from top right to bottom left). 500 µm © Jim Langeland, Steve Paddock and Sean Carroll

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Forming the SegmentsLaying Down the Fundamental Regions Setting the Stage for SegmentationEstablishing the Polarity of the Embryo H T A About 21/2 hours after fertilization, Bicoid protein turns on a series of brief signals from so-called gap genes. The gap proteins act to divide the embryo into large blocks. In this photo, fluorescent dyes in antibodies that bind to the gap proteins Krüppel (orange) and Hunchback (green) make the blocks visible; the region of overlap is yellow. The final stage of segmentation occurs when a “segment- polarity” gene called engrailed divides each of the seven regions into halves, producing 14 narrow compartments. Each compartment corresponds to one segment of the future body. There are three head segments (H, bottom right), three thoracic segments (T, upper right), and eight abdominal segments (A, from top right to bottom left). About 0.5 hr later, the gap genes switch on the “pair-rule” genes, which are each expressed in seven stripes. This is shown for the pair-rule gene hairy. Some pair-rule genes are only required for even-numbered segments while others are only required for odd numbered segments. 500 µm a: © Steve Paddock and Sean Carroll; b-d: © Jim Langeland, Steve Paddock and Sean Carroll Fertilization of the egg triggers the production of Bicoid protein from maternal RN A in the egg. The Bicoid protein diffuses through the egg, forming a gradient. This gradient determines the polarity of the embryo, with the head and thorax developing in the zone of high concentration (green fluorescent dye in antibodies that bind bicoid protein allows visualization of the gradient).

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. Nucleus Microtubules PosteriorAnterior PosteriorAnterior Movement of maternal mRNA bicoid mRNA moves toward anterior end Follicle cells nanos mRNA moves toward posterior end Nurse cells bicoid mRNA nanos mRNA Anterior-posterior development

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Concentration Anterior a. Oocyte mRNAs Posterior nanos mRNA hunchback mRNA bicoid mRNA caudal mRNA

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Concentration Anterior a. Oocyte mRNAs b. After fertilization Posterior nanos mRNANanos protein Hunchback protein Bicoid protein Caudal protein nanos mRNA hunchback mRNA bicoid mRNA caudal mRNA hunchback mRNA bicoid mRNA caudal mRNA

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Concentration Anterior a. Oocyte mRNAs c. Early cleavage embryo proteins b. After fertilization Posterior Nanos protein Hunchback protein Bicoid protein Caudal protein Concentration AnteriorPosterior Nanos protein Hunchback protein Bicoid protein Caudal protein nanos mRNA hunchback mRNA bicoid mRNA caudal mRNA hunchback mRNA bicoid mRNA caudal mRNA nanos mRNA

Fig a. b. c. Dorsal dorsal mutant 400 µm 100 µm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Dr. Daniel St. Johnston/Wellcome Images; b: © Schupbach, T. and van Buskirk, C.; c: From Roth et al., 1989, courtesy of Siegfried Roth Wild-type embryoVentral Dorsal-ventral development

Fig

Fig a Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drosophila HOM genes Thorax Antennapedia complex HeadAbdomen Bithorax complex Fruit fly a. Drosophila HOM Chromosomes labpbDfdScrAntpUbxabd-B Fruit fly embryo abd-A

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Drosophila HOM genes Thorax Antennapedia complex HeadAbdomen Bithorax complex Fruit fly Mouse Hox 1 Hox 2 Hox 3 Hox 4 a.b. Drosophila HOM Chromosomes Mouse Hox Chromosomes labpbDfdScrAntpUbxabd-B Mouse embryo Fruit fly embryo abd-A

SEM of HeLa cell undergoing apoptosis From ATCC photo contest, 2011

a.b. InhibitorCED-9Bcl-2 CED-4Apaf1 Caspase-8 or -9CED-3 Inhibitor: Activator: Caenorhabditis elegansMammalian CellOrganism Inhibition Activation Apoptotic Protease: Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Apoptosis Apoptosis pathway