Ppt on polytene chromosomes of drosophila

DNA and Chromosomes. DNA, Chromosome Centromere, telomere, replication origin Nucleosome, Chromatin, Histone: H1, H2A, H2B, H3, H4 Histone octamer, DNA.

Centromere, telomere, replication origin Nucleosome, Chromatin, Histone: H1, H2A, H2B, H3, H4 Histone octamer, DNA packaging DNA binding proteins, Histone modifications Lampbrush chromosomes (amphibian oocyte) A model for the structure of a lampbrush chromosome A polytene chromosome from Drosophila salivary gland Electron Microscope image of Drosophila polytene chromosome Chromosome puffs RNA synthesis in Chromosome puffs Red: newly synthesized BrUTP; Blue: old ones diffused A model for the structure/


Cell Biology Mrs.Sridevi.

cotton Gossypium hirsutum 52 mango Mangifera indica cassava Manihot utilissima 36 sugarcane Saccharum officinarum 80 Chromosome -Components Secondary Constriction Satellite Primary Constriction Chromosome -Types Polytene Chromosomes Discovery C.G. Balbiani (1881) in the salivary glands of Drosophila. Characteristic features Inter bands, along the length of the chromosome. Balbiani ring or chromosomal puff. Other Name Salivary gland chromosomes, as they occur in the salivary glands. Special Types: Lampbrush/


Drosophila Genetic Laboratory PI: 廖國楨 / 孫以瀚. Information a. Books  Drosophila: A laboratory handbook  The genome of Drosophila melanogaster  The development.

.tw The Basics of Fly Genetics: Fly Chromosomes Female Male X 2L 3R 3L 2R4 Drosophila stocks 1. Wild-type stocks: Oregon-R and Canton-S 2. Mutant Stocks: Bloomington and Umea Stock Centers  Genetic map: e.g. 2-57 cM (centi-Morgan)  No recombination in males Y Type of Mutations Point mutation Inversion Translocation Compound chromosome Duplication Deficiency () ( ) Polytene chromosome Physical mapping for chromosomal rearrangement, duplication and/


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

not plants) – Monosomy for Drosophila chromosome 4 (only 5% of genome) gives live fly but small and with low viability – Monosomy for chromosomes 2 and 3 lethal Issues – Gene dosage effects – Expression of all encoded recessive alleles Trisomy Trisomy/ 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) /


Types of Chromosomal Mutations 1. Variations in chromosome structure or number can arise spontaneously or be induced by chemicals or radiation. Chromosomal.

for Bar. ii. Males hemizygous for Bar have slit-like eyes like those of a Bar/Bar female. b. Cytological examination of polytene chromosomes showed that the Bar allele results from duplication of a small segment (16A) of the X chromosome. Peter J. Russell, iGenetics: Copyright © Pearson Education, Inc., publishing as Benjamin Cummings. Chromosome constitutions of Drosophila strains Peter J. Russell, iGenetics: Copyright © Pearson Education, Inc., publishing as Benjamin Cummings/


Ch.2 Mitosis and Meiosis 有丝分裂与减数分裂 Genetic continuity between cells and organisms of any sexually reproducing species is maintained by the processes of.

: Denature with saturated Ba(OH) 2 then stain with Giemsa. Idiogram Morphological characteristics of chromosomes - Size CHROMOSOME TOPOGRAPHY F Drosophila chromosomes F centromeres F telomeres (later) F euchromatin F heterochromatin F polytene chromosomes CHROMOSOME TOPOGRAPHY Review the process of mitosis, and observe the 4 phases of mitosis Review the process of meiosis, and observe the various phases of meiosis 3.mitosis and meiosis Cell division and Cell Cycle: the events that occur/


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.

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 conjugated to alkaline phosphatase AP substrate results in the formation of an insoluble precipitate at the site of hybridization from Lodish et al., Molecular Cell Biology, 6 th ed. Fig 6-44 Ecdysone produces a characteristic pattern of puffs in polytene chromosomes of salivary glands/


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.

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 conjugated to alkaline phosphatase AP substrate results in the formation of an insoluble precipitate at the site of hybridization from Lodish et al., Molecular Cell Biology, 6 th ed. Fig 6-44 Ecdysone produces a characteristic pattern of puffs in polytene chromosomes of salivary glands/


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.

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 conjugated to alkaline phosphatase AP substrate results in the formation of an insoluble precipitate at the site of hybridization from Lodish et al., Molecular Cell Biology, 6 th ed. Fig 6-44 Ecdysone produces a characteristic pattern of puffs in polytene chromosomes of salivary glands/


Enhance the Understanding of Whole-Genome Evolution by Designing, Accelerating and Parallelizing Phylogenetic Algorithms Zhaoming Yin Advisor: David A.

,-1,3=4 1,3,2 -> 1,-3,-2=2 The possible median order are (g-2)!!. g is the number of genes Genome Rearrangement: Chromosome Level Genome rearrangements observed in Drosophila polytene chromosomes. DOBZHANSKY, T., and A. H. STURTEVANT, 1938 Inversions in the chromosomes of Drosophila pseudoobscura. Genetics 23: 28-64. 9 Genome Rearrangement http://ai.stanford.edu/~serafim/CS374_2006/presentations/lecture17.ppt Genome Rearrangement In 1980s/


Chapter 5 Human Chromosomes and Chromosome Behavior.

, sterile) Turner Syndrome = 45, X (female, sterile) 19 Abnormal Chromosome Number Aneuplody results from nondisjunction: a failure of chromosomes to separate and move to opposite poles of the division spindle The rate of nondisjunction can be increased by chemicals in the environment. 20 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/


Dr Gihan E-H Gawish, MSc, PhD Ass. Professor Molecular Genetics and Clinical Biochemistry Molecular Genetics and Clinical BiochemistryKSU Chromosome Mutations:

groups, and there can even be normal variation within or between populations of one species. OBJECTIVES OF THE COMING SECTION  Some of the ways that chromosome mutations contribute to the evolution of genomes.  Explore and describe the comparative molecular anatomy of genomes. Chromosomal Polymorphism 31  Some natural populations show two or more chromosomal forms, a situation called chromosomal polymorphism.  Drosophila, because of its polytene chromosomes, has been a favorite organism for the study/


The Nucleus 9. 9 The Nucleus Chapter Outline The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm Internal Organization of the Nucleus.

and confirmed in 1984 by studies of polytene chromosomes in Drosophila salivary glands. Figure 9.17 Chromosome organization Internal Organization of the Nucleus Each chromosome occupies a discrete region of the nucleus. They are closely associated with the nuclear envelope at many sites. Many of these associations result in repression of gene expression but some promote transcription of specific genes. Figure 9.18 Organization of Drosophila chromosomes Internal Organization of the Nucleus In mammalian cell/


The Nucleus 10. 10 The Nucleus The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm The Organization of Chromosomes Nuclear Bodies.

suggested in 1885 and confirmed in 1984 by studies of polytene chromosomes in Drosophila salivary glands. Each chromosome was found to occupy a discrete region of the nucleus, called a chromosome territory. Figure 10.16 Chromosome organization (Part 1) Figure 10.16 Chromosome organization (Part 2) Figure 10.17 Organization of Drosophila chromosomes (Part 1) Figure 10.17 Organization of Drosophila chromosomes (Part 2) The Organization of Chromosomes In situ hybridization with fluorescent probes specific for/


BioSci 108 lecture 26 (Blumberg) page 1 © copyright Bruce Blumberg 2000. All rights reserved Bio 108 - 3/13/2000 Molecular Genetics of Pattern Formation.

mitotic recombination and compartment boundaries –in situ hybridization was first perfected and widely applied in Drosophila no easier organism to do in situs in than Drosophilapolytene chromosomes allowed relatively precise mapping of mutations later advances allowed chromosomes to be microdissected and genes in a region to be cloned Reward: genes identified in Drosophila turn out to have close counterparts in virtually all animals, including humans Anatomy/


The Genomics Education Partnership, 2011 Charles Hauser 1, Wilson Leung 3, Chris Shaffer 3, David Lopatto 2, Sarah Elgin 3 and faculty and students of.

academic year to address these aims. Individual projects, common tools, pooled results The Drosophila melanogaster fourth chromosome exhibits an amalgam of heterochromatic and euchromatic properties C C HP 1 Phase James et al,1989 Heterochromatic properties: - Antibody staining of HP1, H3K9me2/3 - Lack of recombination - High repeat density Euchromatic properties: - Banded structure in polytene chromosomes - Gene density similar to other euchromatic domains (~80 genes in the distal/


LECTURE 04: CHROMOSOMAL BASIS OF INHERITANCE I Fhow do we know that genes are parts of chromosomes? Fhow are they arranged on chromosomes? Fare chromosomes.

23, Giemsa stain Fbanding patterns - consistent, chromosome-specific FG-dark & G-light... significance of bands? CHROMOSOMES - TOPOGRAPHY F Drosophila chromosomes F centromeres F telomeres F euchromatin F heterochromatin F polytene chromosomes F chromocenter CHROMOSOMES - TOPOGRAPHY why is this significant? F Zea maize, n = 10 CHROMOSOMES - GENES F single gene ID with FISH CHROMOSOMES - GENES F meaningful relationships ? CHROMOSOMES - GENES F meaningful relationships ? CHROMOSOMES - GENES F repetative genes/


An Introduction to Model Organisms of Development.

of bacteria Gestation : 500,000 offspring in 1 week from single organism Sexual maturity in 3 days Genome : Sequenced! Drosophila /of human disease genes have fly homologues Large repositories of mutant flies available Conservation of patterning between flies and mammals In situ hybridization of whole embryo can reveal patterns of gene expression during development RNA or DNA probes and labeled antibodies are used. Polytene Chromosomes Present in salivary glands of flies Originate from chromosomal/


Chromosome Mutation Relocation of Genetic Material - how do chromosome rearrangements occur? - how can we detect them - what are their genetic and phenotypic.

mapping Create strains carrying duplication or deletions –Small inversions or translocations can result in viable progeny Balancer Chromosomes in Drosophila –Prevent recombination anywhere on a chromosome in a inversion heterozygote Deletions Drosophila Polytene Chromosomes allow deletion loops to be visualized Using multigene deletions for mapping the location of point mutants Human diseases associated with deletions Conceptions involving chromosome abnormalities are relatively common 7.5 up to 15/


Controls Over Genes Chapter 14. Gene Control Which genes are being expressed in a cell depends upon: The type of cell Internal chemical conditions External.

transport processing control transcription control Most Genes Are Turned Off Cells of multicelled organisms rarely use more than 5-10 percent of their genes at any given time The remaining genes are selectively expressed Polytene Chromosomes Occur in salivary glands of midge larvae Consist of multiple DNA molecules Can produce multiple copies of transcripts Chromosome Puff Portion of the polytene chromosome in which the DNA has loosened up to allow transcription/


VII. DNA and Genome Structure A. Search for the Genetic Information B. Determining DNA Structure C. Chromosome Structure.

have a higher density of coding sequences. These can be seen in a ‘polytene chromosome’ VII. DNA and Genome Structure A. Search for the Genetic Information B. Determining DNA Structure C. Chromosome Structure 1. Eukaryotic Chromosomes 2. Bacterial Chromosomes VII. DNA and Genome/409,949~28,000 a flowering plant (angiosperm) See note.angiospermSee note. Drosophila melanogaster122,653,97713,379the "fruit fly" Anopheles gambiae278,244,06313,683Mosquito vector of malaria. Rice3.9 x 10 8 37,544 Sea urchin8.14 x /


Anatomy of the Gene MUPGRET Workshop June 17, 2004.

the condensed state. Under-replicated in polytene chromosomes. Constitutive heterochromatin Present in all cells at identical positions on both homologous chromosome and forms a permanent structural characteristic of a given chromosome pair. Facultative heterochromatin Varies in state between cell types, developmental stages or homologous chromosome. Ex. differential state in homologous chromosomes seen in Barr bodies. Some proposed functions Chromosome level Stabilize centromeres and telomeres Facilitate/


Chapter 5 DNA and Chromosomes Essential Cell Biology FOURTH EDITION Copyright © Garland Science 2014 Alberts Bray Hopkin Johnson Lewis Raff Roberts Walter.

that are segregated to daughter cells during cell division. Fig. 5-1 T. H. Morgan used Drosophila genetics and the giant chromosomes from their salivary glands to show that chromosomes contain the genetic information. Drosophila genetics Giant polytene chromosomes In larval salivary glands -1920s DNA Component of Chromosomes Contains Genetic Information for Virulence Purified DNA (not protein) from heat-killed S strain also transformed. Fig. 5-3 DNA/


Genetics of Axis Specification in Drosophila Part 1 - Basics of Drosophila Embryogenesis Gilbert - Chapter 9.

... Embryos are REALLY tiny! Embryos are quite complex Larval stages, metamorphosis Power of Genetics Polytene chromosomes Ability to manipulate DNA, RNA, Protein made Drosophila a usable developmental bio model organism Revolutionized the study of development, by providing a base to study the molecular genetics of development Early Development of Drosophila Egg is centrolecithal After fertilization, series of superficial cleavages Blastoderm is syncytial until 13th cleavage (256 nuclei!) Nuclei begin/


Chromatin Structure & Genome Organization. Overview of Chromosome Structure Nucleosomes –~200 bp DNA in 120 Å diameter coil –3.4 Å /bp x 200 = 680 Å –680/120.

global gene expression Components –DNA topoisomerase II –SMC proteins –HMGA DNA elements –S/MARS Sequences of DNA to which scaffold proteins bind –LCR DNA elements known to regulate expression of large regions of DNA containing multiple genes –Boundary elements scs elements flank puffs in Drosophila polytene chromosomes Chromosome Loops Chromosome Structure: The Metaphase Chromosome Centromeres DNA sequence –Repetitive DNA elements –Constitutive heterochromatin Protein components –CENP-A, B & C Centromeres/


[V]. Process of Transcription and Transcriptional Control of Gene Expression 1 RNA polymerases and Initiation of transcription Transcriptional elongation.

Histone H1 is as good substrate for Cdc2 kinase suggesting that phosphorylation of H1 may be important for cell division Phosphorylation of ser 10 of H3 is linked to transcriptional activation, chromosome condensation and mitotic progression JIL-1, a kinase that phosphorylate histone H3S10, null mutant in Drosophila showed abnormal structure (unextended structure ) of polytene chromosomes Histone Phosphorylation Affects Chromatin Structure Summary (I) Transcription factors: basal factors, activators/


Conservation of Hawaiian Drosophila using phylogenetic, ecological and population genetic data. Patrick M. O’Grady University of California, Berkeley.

etc) Outline Phylogeny Population Genetics –Placement of the Hawaiian Drosophila & Scaptomyza –Time scale for drosophilid evolution –Ages of major Hawaiian lineages –Ecological associations Introduction –Hawaiian Drosophila Hawaiian Drosophila - 1,000 endemics - diverse behavior/ work with (little known of their ecology, not culturable in the laboratory, polytene chromosomes are not amenable to study). –Historical distribution and abundance data not available. Other groups? Loss of host plants via rarity or/


Control of Animal Development by Steroid Hormones

pulse. *Competence the ability to respond to an inductive signal Third Instar Larva Leg Disc Eversion Adult Larval and Pupal Stages of Drosophila Development A B C D E F A. First instar larva B. Second instar larva C. Third instar larva E/FTZ-F1 protein bound to the 2B5, 74EF, 75B and 93F puff loci in prepupal salivary gland polytene chromosomes. [Lavorgna, et al. (1993) PNAS 90: 3004- 3008] Ectopic expression of ßFTZ-F1 provides E93 with the competence to respond to the late larval ecdysone pulse. [Woodard /


Primer on Annotation of Drosophila Genes GEP Workshop – January 2016 Wilson Leung and Chris Shaffer.

/ Spring 2016 Species in the Four Genomes Paper New species sequenced by modENCODE Phylogenetic tree produced by Thom Kaufman as part of the modENCODE project Manuscript in progress Muller element nomenclature Schaeffer SW et al, 2008. Polytene Chromosomal Maps of 11 Drosophila Species: The Order of Genomic Scaffolds Inferred From Genetic and Physical Maps. Genetics. 2008 Jul;179(3):1601-55 X2L2R3L3R4 X45326 Gene structure nomenclature/


Steroid Control of Leg Development in Drosophila Craig T. Woodard Mount Holyoke College.

larval epidermis, and via invasion of the larval epidermis by cells of the peripodial epithelium and peripodial stalk. Imaginal Disc Eversion Normal Leg Development The role of how in leg imaginal disc morphogenesis The Drosophila how gene has pleiotropic functions /E93 loci in prepupal salivary gland polytene chromosomes. Ectopic expression of ßFTZ-F1 provides E93 with the competence to respond to the late larval ecdysone pulse. ßFTZ-F1 protein binds E93 genomic sequences. Induction of BR-C, E74A and E75A /


Steroid Control of Leg Development in Drosophila Craig T. Woodard Mount Holyoke College.

hormone elicit different responses at different times in development? Drosophila Life Cycle Ecdysone directs metamorphosis Puparium formation Prepupal- pupal transition High titer of ecdysone at the end of 3 rd instar larva initiates entry into metamorphosis Second high/ loci in prepupal salivary gland polytene chromosomes. Ectopic expression of ßFTZ-F1 provides E93 with the competence to respond to the late larval ecdysone pulse. ßFTZ-F1 protein binds E93 genomic sequences. Induction of BR-C, E74A and E75A/


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

on EcR expression during Drosophila mushroom body neuron remodeling and neuroblast clones also Summary of the genetic crosses for the MARCM-based genetic screen Identification of the l(X)48 mutant defective in the pruning of larval-specific axons and dentrites/;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 Cu.Bio. 2000) HYPOTHESIS 1 2 EcR-B1 /


Endocrine Systems 內分泌系統 Wu-Chun Tu Department of Entomology National Chung Hsing University Insect Physiology.

– –Incorporated into the eggs for later use during embryogenesis (follicle cells) – –Stimulate fat body to activate the synthesis of yolk proteins. Testes – –Sheaths cells produce Epidermal cells – –During certain developmental stages Neurohormones : Ovarian ecdysiotropic hormones Testes ecdysiotropin Mode of Action of Ecdysteroids Chromosome Puffs in Drosophila Polytene Chromosomes Early puffs : hormone directly Late puffs Puffing patterns are correlated with the development stage Fig. A model originally/


5 Human Chromosomes and Chromosome Behavior

) 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 = deletion mapping Large deletions are often lethal Fig. 5.16 Gene Duplications Duplication/


Human Karyotypes and Chromosome Behavior

-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 are often lethal Gene Duplications Duplication/


Overview of I519 & Introduction to Bioinformatics.

diet. –Short life cycle: taking about two weeks –Have large polytene chromosomes, whose barcode patterns of light and dark bands allow genes to be mapped accurately  It was chosen in 1990 as one of the model organisms to be studied under the auspices of the federally funded Human Genome Project  Whole genome sequenced in 2000  >10 Drosophila genomes have been sequenced  FlyBase: http://flybase.org/ Biology/


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

function, only havinog one is a 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. Reverse tandem/


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

challenged inherited condition  Long 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


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

7. Diploid numbers of some commonly studied organisms (as well as a few extreme examples) Homo sapiens (human)46 Mus musculus (house mouse)40 Zea mays(corn or maize)20 Drosophila melanogaster (fruit fly)8/ - 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 - /


Ka-Lok Ng Dept. of Bioinformatics Asia University

the alignment of physical and genetic maps Cytogenetic maps are the banding patterns observed through a microscope on stained chromosome spreads Traditional preparation – salivary gland polytene chromosomes 唾液腺多線染色體 (greatly enlarged relative to their usual condition) of insects and / GMOD project Invertebrate Model Organisms A 40 kb region of cytological band 43E of fruit fly, centered on the saxophone gene. Figure 1.14 Drosophila gene annotation Invertebrate Model Organisms Flybase http://www.flybase.org/


Chapter 8 Human Karyotypes and Chromosome Behavior

(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 loss of repeats Unequal crossing over involving eye pigment genes Mechanism of creation of a chromosomes with an inverted segment Pairing of homologous chromosomes in an inversion heterozygote An inversion which does/


Chapter 21 Regulation of Transcription. 21.1 Introduction 21.2 Response elements identify genes under common regulation 21.3 There are many types of DNA-binding.

.24 A protein that binds to the insulator scs ¢ is localized at interbands in Drosophila polytene chromosomes. Red staining identifies the DNA (the bands) on both the upper and lower samples; green staining identifies BEAF32 (often at interbands) on the upper sample. Yellow shows coincidence of the two labels. Some of the more prominent stained interbands are marked by white lines. Photograph kindly provided by/


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

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 gene encodes embryonic hemoglobin; the αD and αA genes encode adult/


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

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 assoc. w protein scaffold of the chromosome. Puff Occasionally a band forms a puff (euchromatin) and becomes active/


DNA Replication Lecture 10 Dr. Attya Bhatti. Mechanism of DNA replication In E-Coli In the late 1950s, Arthur Kornberg successfully identified and purified.

to solve the problem of coordinating the replication of more than one chromosome, as well as replicating the complex structure of the chromosome itself. Eukaryotic origins of replication In eukaryotes, replication proceeds from multiple points of origin. Replication appears to begin at several different sites on eukaryotic chromosomes. Eukaryotic origins of replication Figure: Replication pattern in a Drosophila polytene chromosome revealed by autoradiography. Several points of replication are seen within/


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

, MSL1, and MSL3 DCC binds to high affinity sites on X chromosome DCC spreads to nearby sites on active chromatin H4K16 acetylation impedes formation of condensed chromatin structure from Straub and Becker, Nature Rev.Genet. 8, 47 (2007) DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates/


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

, MSL1, and MSL3 DCC binds to high affinity sites on X chromosome DCC spreads to nearby sites on active chromatin H4K16 acetylation impedes formation of condensed chromatin structure from Straub and Becker, Nature Rev.Genet. 8, 47 (2007) DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates/


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 regulation P48-52 4 stages: / 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 levels of the E-cadherin If E-cadherin is removed, the oocyte is/


Imprinting Expression of only one allele of a locus Only ~100 genes in mammals are imprinted Most imprinted genes are involved in growth control or postnatal.

of the genes controlling fur color is on the X chromosome B – orange b - black Random X inactivation early in embryonic development leads to patchworks of skin cells expressing each allele Female mammals are genetic mosaics The Dosage Compensation Complex in Drosophila/ Nature Rev.Genet. 8, 47 (2007) DCC is Localized to the X Chromosome DCC localization is determined by staining of polytene chromosomes with anti-MSL1 DCC associates almost exclusively with transcribed regions DNA Replicates by a /


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

. 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 adult mxc G43 adult Loss of GSCs after 10 days of H1 RNAi expression in the germline Rescue of mxc mutant germline phenotype with germline specific expression of H3 RNAi H1 RNAi expressed in the germ/


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