Ppt on polytene chromosomes drosophila

5 Human Chromosomes and Chromosome Behavior

has a relatively mild effect Trisomy-X = 47, XXX (female) Double-Y = 47, XYY (male) Klinefelter Syndrome = 47, XXY (male, sterile) Turner Syndrome = 45, X (female, sterile) Chromosome Deletions Deletions = missing chromosome segment Polytene chromosomes of Drosophila can be used to map physically the locations of deletions Any recessive allele that is uncovered by a deletion must be located inside the boundaries of the deletion/


Rein et al., 2002 Current Biology The mushroom bodies (MBs) in the adult Drosophila brain.

B ecdysone receptor for mushroom body neuronal remodeling in Drosophila Zheng et al., Cell (2003) 112:303-315 TGF-  signaling activates steroid hormone receptor expression during neuronal remodeling in the Drosophila brain Boulanger et al., Nature Neuroscience (2011) /Hr39 -/- PUP usp -/- ; Hr39 -/- ;UAS-ftz-f1 + PUP ECR-B1  neuron pruning + ftz-f1 - FTZ-F1 is binding the polytene chromosome band 42 A (EcR) (Lavorgna et al PNAS 1993) - at 10h APF reduced expression of EcR in hs-ftz-f1 RNAi (Lam and Thummel/


Human Karyotypes and Chromosome Behavior

, XXX (female) double-Y=47, XYY (male) Klinefelter Syndrome=47, XXY (male, sterile) Turner Syndrome=45, X (female, sterile) Fragile-X syndrome= X chromosome instability resulting from high copy number of trinucleotide repeat Chromosome Deletions Deletions = missing chromosome segment Polytene chromosomes of Drosophila can be used to map physically the locations of deletions Testcross mapping shows which wild-type alleles are lost by deletion Large deletions/


Mammalian Cytogenetics Chromosome structure & karyotype Gene 405: Mammalian Genetics Fall 2002 17 September, 2002.

) Homo sapiens (human)46 Mus musculus (house mouse)40 Zea mays(corn or maize)20 Drosophila melanogaster (fruit fly)8 Xenopus laevis (South African clawed frog)36 Caenorhabditis elegans (microscopic roundworm)/ - fertility - Abnormalities in offspring abnormal gamete formation Polytene Chromosomes Giant chromosomes - dipteran Begin as normal chromosomes Repeated rounds of DNA replication (endoreplication); & no cell division Become large banded chromosomes Centromere – no endoreplication Bundle in a mass - /


Chapter 8 Human Karyotypes and Chromosome Behavior

increases with Mother’s age Pairing and segregation of 3 homologous chromosomes in meiosis I This kind of chromosome pairing occurs in trisomics (2n+1) or triploids (3n) Mapping the deletion of part of a chromosome segment by testcrosses and uncovering of recessive genes Mapping of genes in Drosophila using overlapping deletions and polytene chromosomes Unequal crossing over of misaligned repeat sequences leads to gain or/


LECTURE CONNECTIONS 11 | Chromosome Structure © 2009 W. H. Freeman and Company and Transposable Elements.

two nucleosomes. High-order chromatin structure: when nucleosomes fold on themselves to form a dense, tightly packed structure. Changes in Chromatin Structure Polytene chromosome: giant chromosomes found in certain tissues of Drosophila and some other organisms. Chromosomal puffs: localized swellings of the chromosome. Chromatin have a relaxed structure. DNase I sensitivity is correlated with the transcription of globin genes in erythroblasts of chick embryos. The U/


Chapter 8 Human Karyotypes and Chromosome Behavior Jones and Bartlett Publishers © 2005.

problem. ‘Cri du Chat’ syndrome in humans: –Deficiency of a part of chromosome 5 Mapping the deletion of part of a chromosome segment by testcrosses and uncovering of recessive genes Mapping of genes in Drosophila using overlapping deletions and polytene chromosomes Duplications Mutations can produce an extra copy of a part of a chromosome called a duplication. Tandem duplication – same sequence, adjacent to the original copy/


Chromosomes Cytogenetics: study which links chromosome variations to specific traits Chromosome: Dark heterochromatin (repetitive DNA) Light euchromatin.

narrow face with protruding chin, enlarged ears  Increased testicular size (gynecomastia)  Gene = FMR1 (sequence of 3 nucleotides repeated many times)  Link between an autosomal fragile site and lung cancer Specialized Chromosomes Polytene Chromosomes: salivary, rectal, midgut Can be seen in interphase Individual bands called chromomeres Undergo uncoiling (puff) in Drosophila Lampbrush Chromosomes: meiotic chromosomes In vertebrate oocytes and insect spermatocytes


Chromatin Structure and Function BSCI 420. Chromatin is the complex of DNA and proteins that comprise eukaryotic chromosomes. 2 classes of chromatin proteins:

during a long meiotic prophase to synthesize RNAs & proteins to be stored in the egg for early development. Phase-contrast and fluorescent micrographs of lampbrush chromosomes B. Polytene chromosomes of Drosophila Have replicated DNA 10X -> 1024 copies of chromosome side by side without separation by mitosis. Bands are chromatin domains with an ave of 3 genes in them. Interbands are probably regions of DNA that/


Drosophila melanogaster Genetic studies Microsurgical manipulation One of the best understood developmental systems 13,600 genes Axis determination Signaling.

Drosophila melanogaster Genetic studies Microsurgical manipulation One of the best understood developmental systems 13,600 genes Axis determination Signaling pathway Transcriptional / continues meiosis Oocyte—4 ring canals 15 cells become nurse cells after germarium nurse cells left meiotic cycle, grow rapidly without division, and form polytene chromosomes A/P during oogenesis The oocyte move towards one end in contact with follicle cells Both the oocyte and the posterior follicle cells express high /


Mxc mutant alleles: Lethal (L1-L2) Pharate lethal viable Drosophila spermatogenesis mxc mutations affect germ cell development mxc mutations causes loss.

affect the DNA repair response following replicative stress multi sex combs (mxc) controls histone biosynthesis and replicative stress response in Drosophila Severine Landais and Leanne Jones, Salk Institute, San Diego, CA, USA. H1 10 mxc G46 ;Nanos-Gal4>Gal4RNAi,/ White et al, JCB, Vol. 193 (4) 2011. Impaired histone mRNA levels in mxc mutants Decompaction of polytene chromosomes In mxc G43 salivary glands Germline specific H1 protein depletion in mxc mutants gonads Control larvae mxc G43 larvae Control /


Genetics: From Genes to Genomes

Chapter 13 Deletion loops also form in polytene chromosomes of Drosophila deletion heterozygotes In Drosophila, homologous chromosomes pair with each other during interphase Comparison of banding patterns in polytene chromosomes of a deletion heterozygote can reveal the /or display Hartwell et al., 4th edition, Chapter 13 Using deletions to assign genes to bands on Drosophila polytene chromosomes Complementation tests with several deletions used to determine the locations of white (w), roughest (rst), /


Welcome Each of You to My Molecular Biology Class.

signaling molecules. The First Genome Maps Were Produced in Drosophila  Useful features of the flies in experimental research : Fecundity Rapid life cycle Four chromosomes (two large autosomes, a smaller X, and a very small fourth chromosome) Polytene chromosomes Drosophila melanogaster Endoreplication in the absence of mitosis generates enlarged chromosomes in some tissues of the fly Figure 21-17 Polytene chromosomes  Two major discoverise by the Morgan lab in 1910/


Cell Biology & Molecular Biology

both band and interband regions. Some bands contain multiple genes, and some bands seem to lack genes altogether. Figure 4-40. An electron micrograph of a small section of a Drosophila polytene chromosome seen in thin section. Bands of very different thickness can be readily distinguished, separated by interbands, which contain less condensed chromatin. (Courtesy of Veikko Sorsa.) It seems likely that the/


Chapter 08 *Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. *See separate FlexArt PowerPoint.

lie together in a parallel fashion This bundle is termed a polytene chromosome Polytene Chromosomes 8-55 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Figure 8.19 (a) Repeated chromosome replication produces polytene chromosome. (c) Relationship between a polytene chromosome and regular Drosophila chromosomes L R Chromocenter Each polytene arm is composed of hundreds of chromosomes aligned side by side. 4 32 x L R Copyright © The McGraw/


Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 14-1 Powerpoint to accompany Genetics: From Genes to Genomes Third.

of about 5000 bands ranging from 3kb to 150kb 14-11 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Deletion heterozygotes form visible deletion loops in Drosophila polytene chromosomes. 14-12 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Deletions can be used to locate genes. Deletions to assign genes to bands on/


Genetic Model Organisms worm mouse fish yeast fruit fly weed.

of eyeless using the UAS-Gal4 system Specialized chromosomes Discovered by Balbiany in 1881 in salivary gland of drosophila larva (3 rd instars) Why salivary gland of drosophila larva will have Polytene Chromosomes???????????????? Polytene chromosomes Drosophila Polytene chromosome Drosophila Karyotype 1933, Painter showed the banding pattern in Drosophila 1935, Bridges Banding pattern is fixed in a particular chromosome in a particular species Polytene chromosome is found in 3 rd instar larva of/


CHAPTER 10 The Nature of the Gene and the Genome.

to a sublethal dose of X-rays increases the rate of spontaneous mutations. Cells from the salivary gland of Drosophila have giant polytene chromosomes. Polytene chromosomes have been useful to observe specific bands correlated with individual genes. “Puffs” in polytene chromosomes allow visualization of gene expression. Polytene chromosomes 10.3 The Chemical Nature of the Gene (1) DNA is the genetic material in all organisms. The Structure of DNA/


Finding Genes in a New Fly Genome: Teaching about Genes/Genomes via Bioinformatics Research Sarah Elgin, Anya Goodman, Wilson Leung Eric Tsoi, Charlene.

and students of the Genomics Education Partnership Goal: to understand the organization and functioning of the dot chromosome in Drosophila, an unusual heterochromatic domain. Funding: HHMI Professors Program NIH General Medical Sciences, National Human Genome Research/ - loss of DH sites - regular nucleosome array Looking for heterochromatic proteins by immunofluorescent staining of the polytene chromosomes: discovery of HP1a C C HP1 Phase James & Elgin,1986; James et al 1989 Heterochromatin-associated /


Lab 8: Mitosis, Meiosis, and Chromosomes

in pollen sacs Pollen grains will be in different stages of meiosis Experiment 3: Polytene Chromosomes of Drosophila Today: Examine prepared slides of polytene chromosomes found in Drosophila melanogaster (fruit fly) Located specifically in: The gut. Malphigian tubules (excretory organs) of larvae. Footpads of adults. Salivary glands of larvae Polytene Chromosomes of Drosophila Giant chromosomes Have undergone many rounds of DNA duplication without cell division Large size Easily visible under/


Figure 6-16. Initiation of transcription of a eucaryotic gene by RNA polymerase II. To begin transcription, RNA polymerase requires a number of general.

et al., Mol. Cell 3:297–307, 1999.)Figure 7-119 Figure 7-62. Localization of a Drosophila insulator-binding protein on polytene chromosomes. A polytene chromosome (see pp. 218–220) was stained with propidium iodide (red) to show its banding patterns—with/ bands appearing bright red and interbands as dark gaps in the pattern (top). The positions on this polytene chromosome that are bound by a particular insulator protein (called BEAF) are stained bright green using antibodies directed against the/


1 Recombination and Mapping (cont’d). 2 Interference Interference: this is a phenomenon in which the occurrence of one crossover in a region influences.

to map genes to specific regions of a chromosome. For example in Drosophila in some cells the chromosomes become highly replicated and exhibit very characteristic banding patterns: 26 In situ hybridization Polytene chromosomes Salivary glands Squash on slide Denature/Stain polytene chromosomes label gene probe Hybridize probe to polytene chromosomes Autoradiography 27 Drosophila X chr tip This map is actually very crude. The Drosophila genome consists of about 165 Mega base/


1 The Big Picture: an outline of the concepts covered to date 1.Genes are physical units of hereditary that carry information from one generation to the.

to map genes to specific regions of a chromosome. For example in Drosophila in some cells the chromosomes become highly replicated and exhibit very characteristic banding patterns: 14 In situ hybridization Polytene chromosomes Salivary glands Squash on slide Denature/Stain polytene chromosomes label gene probe Hybridize probe to polytene chromosomes Autoradiography 15 Drosophila X chr tip This map is actually very crude. The Drosophila genome consists of about 165 Mega base/


Genetics: From Genes to Genomes

Companies, Inc. Permission required to reproduce or display Structure of the Drosophila Genome Chromosomes of Drosophila Four chromosomes designated 1-4 XY sex determination (XX females, XY males) Sex determined by X:A ratio Figure D.3 Fig. D.3 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Giant polytene chromosomes of larval salivary gland are key tools Replicate 10-11 times/


Polycomb, trithorax, and maintenance of gene expression

of PcG-dependent repression of reporter genes Bound by PcG proteins in vivo (in polytene chromosomes and by cross-linking experiments) Repression is enhanced by homologous pairing of the transgenes /chromosomal interactions in Drosophila. Genes Dev 17, 2406-2420. 2. Silencing of mini-white depends on PcG and trxG proteins Fab-7 Pc +/+ Pc -/+ trx +/+ trx -/+ UAS-lacZ white 3. Recruitment of PcG and trxG proteins to PREs: analysis in Fab-7 by a combination of immunostaining and FISH in polytene chromosomes/


Heterochromatineuchromatin (and facultative heterochromatin) Different types of chromatin Constitutive heterochromatin: constitute ~ 10% of nuclear DNA.

to balance expression dosage of X-linked genes? bands inter-bands Drosophila polytene chromosomes Drosophila genome has 4 chromosomes polytene chromosomes result from endoreplication (DNA replication without cytokinesis)  giant chromosomes that are easily visible 2048 identical DNA strands X chromosome in Drosophila DAPI (DNA) Ac H4 X X the X chromosome of male Drosophila is transcriptionally twice as active increased transcription of the active X chromosome is marked by hyper-acetylated histones X/


Cavalli Lab Introduction in: Epigenetic regulation by Polycomb and trithorax group proteins Giacomo CAVALLI. Montpellier, December 2006.

histones but does not necessitate histone tails Features of PREs and TREs, and examples of how they are studied in Drosophila (No PREs characterized yet in vertebrates) 1. Example of PcG-dependent spatial specific silencing of homeotic genes PcG /3. Recruitment of PcG and trxG proteins to PREs: analysis in Fab-7 by a combination of immunostaining and FISH in polytene chromosomes (immuno-FISH) 24A 25E5 transgene DAPI Immunostaining of PH protein FISH Immuno-FISH Fab-7UAS-lacZwhite Transgene : 4. Recruitment /


Chapter 21 Model Organism 2003 级生科 2 班 苏亮 200331060158.

not.  Hermann J. Muller provided the first evidence that environmental factors can cause chromosome rearrangements and genetic mutations.  Bridges used the polytene chromosomes to determine a physical map of the Drosophila genome (the first produced for any organism).  Figure 21-17 Genetic maps, polytene chromosome, and deficiency mapping  A variety of additional genetic methods were create to establish the fruit fly as the premiere model organism/


Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr www.cengage.com/biology/starr Chapter 10 Controls Over Genes (Sections 10.1 - 10.5)

gene copies affects how fast its product is made Polytene chromosomes consists of hundreds or thousands of copies of the same DNA molecule Drosophila Polytene Chromosomes Giant polytene chromosomes form in Drosophila salivary gland cells by repeated DNA replication Transcription /Binding of transcription factors to special sequences in DNA slows or speeds transcription. Chemical modifications and chromosome duplications affect RNA polymerase’s physical access to genes. 1 mRNA Processing New mRNA cannot leave/


Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr www.cengage.com/biology/starr Chapter 10 Controls Over Genes (Sections 10.1 - 10.5)

gene copies affects how fast its product is made Polytene chromosomes consists of hundreds or thousands of copies of the same DNA molecule Drosophila Polytene Chromosomes Giant polytene chromosomes form in Drosophila salivary gland cells by repeated DNA replication Transcription /Binding of transcription factors to special sequences in DNA slows or speeds transcription. Chemical modifications and chromosome duplications affect RNA polymerase’s physical access to genes. 1 mRNA Processing New mRNA cannot leave/


©2000 Timothy G. Standish John 15:4 4Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye,

sequenced The sequenced portion is euchromatin thought to be richer in gene sequences than the remaining heterochromatin Drosophila has a haploid number of 4: 3 autosomes plus 1 sex chromosome Polytene chromosomes can be easily observed in the salivary glands of larvae ©2000 Timothy G. Standish Telomere Chromosome Morphology Arm Stained polytene chromosomes exhibit distinctive banding patterns Centromere Proximal Distal Proximal Distal ©2000 Timothy G. Standish Telomere/


10/22/2015fatchiyah, JB UB1 Fatchiyah, Ph.D. Lab. Molecular Biology Brawijaya University.

cell from bat pancreas nucleolus Polytene Chomosome of Drosophila as Giant chromosome 10/22/2015fatchiyah, JB UB36 Phase-contrast image of Drosophila melanogaster polytene cromosomes. A. The end of the X-chromosome is marked with an arrow. Chromocentre is in the upper right corner. B. Shows a magnification of chromomere and interchromomere bands Polytene chromosome 10/22/2015fatchiyah, JB UB37 W-chromosome Yeast Artificial Chromosome 10/22/2015fatchiyah, JB UB38/


מבנה הקשר הפוספודיאסטרי 1) קשר 3 – 5 פוספו די-אסטרי 2) כיווניות

universal Representative forms forming typical interphase chromosome Chromosome at mitosis Lampbrush chromosomes (amphibian oocyte, immature eggs) A model for the structure of a lampbrush chromosome Chromomeres: highly condensed and in general not expressed until unfolding A polytene chromosome from Drosophila salivary gland Dark bands and interbands Electron Microscope image of Drosophila polytene chromosome Folding and refolding at a time course of 22 hours Chromosome puffs Folding and refolding at a/


dsDNA כיווניות קשר פוספו A:T and G:C  = 10 -10.

features maybe universal Representative forms forming typical interphase chromosome Chromosome at mitosis The Global Structure of Chromosomes Lampbrush chromosomes (amphibian oocyte, immature eggs) A model for the structure of a lampbrush chromosome Chromomeres: highly condensed and in general not expressed until unfolding A polytene chromosome from Drosophila salivary gland Dark bands and interbands Electron Microscope image of Drosophila polytene chromosome Chromosome puffs Folding and refolding at a time/


מבנה הקשר הפוספודיאסטרי 1 ) קשר 3 – 5 פוספו די - אסטרי 2 ) כיווניות 3 ) קצה ‘ 5 קצה ‘ 3 4 ) במעלה או במורד הזר ם (upstream or downstream)

features maybe universal Representative forms forming typical interphase chromosome Chromosome at mitosis The Global Structure of Chromosomes Lampbrush chromosomes (amphibian oocyte, immature eggs) A model for the structure of a lampbrush chromosome Chromomeres: highly condensed and in general not expressed until unfolding A polytene chromosome from Drosophila salivary gland Dark bands and interbands Electron Microscope image of Drosophila polytene chromosome Chromosome puffs Folding and refolding at a time/


This presentation was originally prepared by C. William Birky, Jr. Department of Ecology and Evolutionary Biology The University of Arizona It may be used.

accuracy and will not update the lectures, which were written when the course was given during the Spring 2007 semester. Section 16 Variation in Chromosome Nunber and Structure Indian Muntjac2N = 6/7 Chinese Muntjac2N = 46 Polytene Chromosomes Some insects, including Drosophila: During differentiation of some tissues (salivary glands, Malpighian tubules, etc.) cells go through repeated S phases (e.g. 10) without mitosis --> polyploid or/


Mutations 1. 2 What is a gene? ---TTGACAT------TATAAT-------AT-/-AGGAGGT-/-ATG CCC CTT TTG TGA ---AACTGTA------ATATTA-------TA-/-TCCTCCA-/-TAC GGG GAA.

genes to specific regions of a chromosome. For example in Drosophila in some cells the chromosomes become highly replicated and exhibit very characteristic banding patterns: 20 In situ hybridization Salivary glands Squash on slide Denature/Stain polytene chromosomes label gene probe (you can only use this method if you have the gene cloned) Hybridize probe to polytene chromosomes Autoradiography Chromosome loss/gain 21 Chromosome instability- Elevated gain or loss/


生物技術學 - 許濤老師授課內容 104/2/25-104/3/11 Biotechnology involves the use of living organisms in industrial processes-particularly in agriculture, food processing.

family (Brassicaceae). Courtesy of Dr. Jeremy Burgess, Science Photo Library. FIGURE 1.22 Companion site for Biotechnology. by Clark Copyright © 2009 by Academic Press. All rights reserved. 39 Polytene Chromosome Fluorescent staining of polytene chromosome from Drosophila. FIGURE 1.18 Companion site for Biotechnology. by Clark Copyright © 2009 by Academic Press. All rights reserved. 40 The Zebrafish, Danio rerio This fish is used as a/


Biology 2250 Principles of Genetics Announcements Lab 4 Information: B2250 (Innes) webpage Lab 4 Information: B2250 (Innes) webpage download and print.

) - euchromatin (light) 4. Banding patterns: a) staining Giemsa bands a) staining Giemsa bands b) polytene chromosomes (flies) b) polytene chromosomes (flies) G-bands Paint of Chr-22 “Paint” Structural Abnormalities Normal a b c d e f / homologues) + + + homologues) + + + deletion deletion Phenotype: + b + + Deletion Mapping Prune pn Structural Abnormalities Deletion: notch-wing (Drosophila) Phenotype Phenotype Genotype wing survival N + N + normal alive N + N + normal alive N + N notch alive N + N notch /


Mutations 1. 2 What is a gene? ---TTGACAT------TATAAT-------AT-/-AGGAGGT-/-ATG CCC CTT TTG TGA ---AACTGTA------ATATTA-------TA-/-TCCTCCA-/-TAC GGG GAA.

genes to specific regions of a chromosome. For example in Drosophila in some cells the chromosomes become highly replicated and exhibit very characteristic banding patterns: 19 In situ hybridization Salivary glands Squash on slide Denature/Stain polytene chromosomes label gene probe (you can only use this method if you have the gene cloned) Hybridize probe to polytene chromosomes Autoradiography Chromosome loss 20 Chromosome instability- Elevated gain or loss of/


Rowan University Spring Semester Mrs. Patricia Sidelsky 2008 Rowan University Spring Semester Mrs. Patricia Sidelsky 2008.

experimental model for the study of modern genetics- the fruit fly – Drosophila melanogaster  The white eyed male mutant appeared in a culture of flies in the fly room and this was the beginning of a search for mutants White and Wild type  Easy to cultivate  Prolific progeny  Small and inexpensive  Large polytene chromosomes  Diploid number 8  Many mutations  Easy to cultivate  Prolific progeny/


Biology 2250 Principles of Genetics Announcements Lab 4 Information: B2250 (Innes) webpage Lab 4 Information: B2250 (Innes) webpage download and print.

) - euchromatin (light) 4. Banding patterns: a) staining Giemsa bands a) staining Giemsa bands b) polytene chromosomes (flies) b) polytene chromosomes (flies) G-bands Paint of Chr-22 “Paint” Structural Abnormalities Normal a b c d e f / homologues) + + + homologues) + + + deletion deletion Phenotype: + b + + Deletion Mapping Prune pn Structural Abnormalities Deletion: notch-wing (Drosophila) Phenotype Phenotype Genotype wing survival N + N + normal alive N + N + normal alive N + N notch alive N + N notch /


Organization of DNA Within a Cell from Lodish et al., Molecular Cell Biology, 6 th ed. Fig 6-1 2 meters of DNA is packed into a 10  m diameter cell.

Cell Biology, 6 th ed. Fig 6-30 Packing of Chromatin Scaffold-associated regions can act as boundaries Condensed chromosomes are visible during metaphase from Lodish et al., Molecular Cell Biology, 5 th ed. Fig 10-24 Genes Can be Localized on Drosophila Polytene Chromosomes Polytene chromosomes exhibit a characteristic banding pattern Localization of a gene by in situ hybridization Biotinylated probe was detected by avidin/


© 2012 Pearson Education, Inc. Lectures by Kathleen Fitzpatrick Simon Fraser University Chapter 23 The Regulation of Gene Expression.

came from microscopic visualization of certain insect chromosomes In the fruit fly, tissues such as the salivary glands contain large polytene chromosomes © 2012 Pearson Education, Inc. Polytene chromosomes Polytene chromosomes form by successive replication without subsequent division/ of transcription © 2012 Pearson Education, Inc. Chromosome puffs and ecdysone As the fruit fly (Drosophila) larvae progress through various stages, the pattern of chromosome puffing changes The puffs respond to the steroid /


[IV] The Role of Chromatin Structure in Control of Gene Expression Overview of levels of control of gene expression Chromatin structure in active or potentially.

Insulator blocks the activity of an enhancer. It can also block the sprading of heterochromatin Insulator sequence was first observed in Drosophila polytene chromosome Upon heat shock, Two chromosome puffs are found in band 87A; these two puffs contain Hsp70 mRNA Upon analysis of Drosophila genome, two scs (specialized chromatin sites) are found These two sites are found at the band flanking the Hsp70 gene/


PowerPoint Presentation Materials to accompany

, it has a fairly crude limit of resolution In most species, it is accurate within limits of ~ 5 million bp The resolution is much better in species that have polytene chromosomes Such as Drosophila melanogaster 20-9 Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display In situ Hybridization In situ hybridization can locate the position of a gene at/


Regulation by changes in chromatin structure Active chromatin.

euchromatin, not heterochromatin Cells that are actively expressing their genes have larger nuclei than do quiescent cells. Activation of particular sets of genes in Drosophila generates visible puffs at defined loci on the polytene chromosomes. Lampbrush chromosomes show transcription in the more extended, open regions of the chromosomes. Puffs on polytene chromosomes Heterochromatin is not transcribed Position effect variegation Wild-type w+ gene produces red eyes in/


Chapter 24 Evolutionary Genetics © John Wiley & Sons, Inc.

and Fy b ). A Human Polymorphism © John Wiley & Sons, Inc. Polymorphism and ethnic groups Variation in Chromosome Structure (genetic variability).  Drosophila polytene chromosomes afford researchers an opportunity to look for variation in chromosome structure in natural populations.  There have been identified many rearrangements of the banding patterns in the polytene chromosomes © John Wiley & Sons, Inc. Puffs Variation in Protein Structure  Amino acid differences in proteins can be/


Gene350 Animal Genetics Lecture 4 30 July 2009. Last Time Mendelian genetics – Terminology – Law of segregation – Law of independent assortment Variations.

direct repeats can result in an internal deletion Compensation Loop in a Polytene Chromosome Create partially hemizygous condition and result in phenomenon called pseudodominance Duplications Section of chromosome occurs more than once in a haploid equivalent (genome) – Commonly /Immunoglobulin, T-cell receptor and MHC families make up a super family For fifty single copy genes in Drosophila, have multiple copies in humans Gene Duplication and Evolution Yeast genome has about 5000 genes with about 55 /


Genome Rearrangements. Basic Biology: DNA Genetic information is stored in deoxyribonucleic acid (DNA) molecules. A single DNA molecule is a sequence.

a different order c) A series of rearrangements transforms one genome into the other History of Chromosome X Rat Consortium, Nature, 2004 Dobzhansky’s Experiment Drosophila melanogaster life cycle taken from FlyMove Giant polytene chromosomes Modified from T.S. Painter, J. Hered. 25:465–476, 1934. Harvesting polytene chromosomes taken from BioPix4U Dobzhansky’s Experiment Standard and Arrowhead arrangements differ by an inversion from segments 70/


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