lecture_Drosophila

lecture_Drosophila - Functional genomics in lower model...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
III. Drosophila Functional genomics in lower model organisms
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
I . The basics: A.Why do we use flies? B.Terminology and symbols 1.Chromosomes 2.Balancers 3.Genotypes
Background image of page 2
1. Drosophila has 4 chromosomes : Named 1 (=X or Y), 2, 3 and 4 (chromosome 4 is very tiny and poor in genes) Each autosome has 2 arms that are simply referred to as left (L) and right (R) The position of genes on the chromosomes can be referred to as numbers : X = 1-20 2L= 21-40 2R= 41-60 3L= 61-80 3R= 81-100 4= 101-102 Alternatively, positions on the chromosome are defined by recombination units -> allows to know the expected recombination frequency between 2 genes on a chromosome arm
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2. Balancers chromosome: 1. = a chromosome with one or more inverted segments (suppresses recombination – cross over) 2. They are homozygous lethal 3. Contain one or more marker genes (recessive + dominant) Each chromosome in Drosophila has its own set of balancers. These balancers are numbered numerically and each has its own dominant and recessive markers, though some balancers are "upgrades" of earlier balancers and often share the same markers. Balancers allow to keep stocks of heterozygous mutants alive and stable without the need of selection (see later)
Background image of page 4
3. Genotypes – Nomenclature •Chromosomes are written in order, as follows, with a semi-colon separating each chromosome. X/Y; 2; 3; 4 • Genotypes are listed only when a mutation is present and are italicized. • Recessive mutations are written in lower case (e.g. w for white gene), • Dominant mutations are capitalized (e.g. Roi for rough eye). • If a particular allele is present that allele is superscripted (e.g. norpAP41 ). • Anything not listed is assumed to be wild type. • If more than one mutation is present on a chromosome, the mutations are listed from left to right corresponding to the left and right arms of each chromosome: arr1 cn bw • If a mutation is homozygous then the mutation is written only once as follows: cn bw • If heterozygous then written as follows: cn/+ bw /+ or cn bw /+ + or cn bw /+
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
3. Genotypes – Nomenclature (continued) • Deficiencies: Df(2L)VA= Deficiency of the left (L) arm of chromosome 2 that includes the gene Venea abnormeis (VA). • Transpositions: Tp(1;3)HF308= Transposition involving the X and 3 rd chromosome. • Inversions: In(2LR)SMC8= Inversion of the left (L) and right (R) arm of the 2nd chromosome. • Translocations: T(1;3)Th1= Translocation between the 1st (X) chromosome and 3rd chromosome. • Commas follow rearrangements and indicate mutations present: e.g. In(2LR)SM1, al 2 Cy cn2 sp2 = Inversion involving the left (L) and right (R) arms of chromosome 2 with the following mutations present: aristaless ( al ), Curly ( Cy ), cinnabar ( cn ), and speck ( sp ).
Background image of page 6
Why Drosophila ? • easy and cheap to rear in the lab
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/28/2010 for the course WE BIBI000000 taught by Professor Johangrooten during the Spring '10 term at Ghent University.

Page1 / 67

lecture_Drosophila - Functional genomics in lower model...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online