Introduction to Drosophila Techniques & P1 x P1 Matings

Drosophila melanogaster • Scientific name: Drosophila melanogaster • (must be italicized or underlined, written text)

• Common name: “fruit fly” • Characteristics of “normal” WILD-TYPE: • Wings, for flight • Red eyes

• Observe fly vial – note these characteristics

Female vs. Male Sex combs

Female •Less banding at tip of abdomen

Male •Darker banding on abdomen (darker butts!)* *Exception: young males may have underdeveloped band coloring & may appear similar to females.

•ALL males have SEX COMBS on forelimbs.

Drosophila Life Cycle *SEE BACK COVER OF CAROLINA DROSOPHILA MANUAL.

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Egg: very small white; may be seen stuck to tip of female’s abdomen

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Larva: “maggots” – will be found eating blue culture media/food

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Pupa: growth stage – will turn dark just before adults emerge.

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Adults: common fruit fly (as seen in lab)

/egg

Culturing Techniques *TA will demonstrate . *SEE CAROLINA DROSOPHILA MANUAL (Culturing pg 4-8, Anesthetizing pg 9) •

Mix 1:1 ratio of Formula 4-24 Blue, culturing media (food), & water in a clean fly vial.

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All to sit out to dry without sponge cap.

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Add 3 – 5 grains of yeasts. Do not add more yeast…it will kill your flies (CO2 poisoning).

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Carefully, anesthetize the adult flies using FLYNAP. – Wear gloves. DEMO.

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Place sleeping flies on index card & observe with dissecting microscope.

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Use paintbrush to carefully separate males and females.

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To set up a cross: add ~4 males + ~4 females of the same ‘type’ to each new culture vial. Name: B. Reo & J. Jamison – Keep vial on its side until flies awaken. Otherwise, Section: 001 (Tues AM lab) they get stuck in the food

Date: 1/21/2014

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Label your new culture vial!

P1: 5

(+,+) x 5

(ap, ap)

Genotypes vs. Phenotypes GENOTYPE

PHENOTYPE

•The genetic make-up of an individual.

•The physical expression of those genes.

•The genes (alleles)

•The traits

Example:

Example:

Wild-type fly Genotype = (+, +)

Wild-type fly Phenotype = winged, red-eyes (“normal”)

Drosophila Normal vs. Mutants “NORMAL”

WING MUTATION (apterous)

EYE MUTATION (white-eyed)

Dominant Trait

Autosomal Recessive

Sex-Linked

brown eyes, dark hair

Tay-sachs, cystic fibrosis

Hemophilia, colorblindness

Genotype(s):

(+, +) or (+, ?)

(ap, ap)

(Xw, Xw) or XwY

Phenotype:

“normal” fly with normal wings & red eyes

(wild-type) Dominant or Recessive? Human Examples

Mutation:

None

Wingless fly

(Note:

White eyes

has red eyes)

(Note: has normal wings)

Chromosome #2

Chromosome #1 (sex chromosome in flies)

Pictures:

Chromosomes *SEE PAGE 23 OF CAROLINA DROSOPHILA MANUAL.

• Drosophila have 4 pairs of chromosomes, 8 total. – Chromosomes 2 – 4 are autosomal. – One pair = sex chromosomes (Chr #1)

• Humans have 23 pairs of chromsomes, 46 total. – Chromosomes 1 – 22 are autosomal. – One pair = sex chromosomes (Chr #23, X or Y)

Chromosomes *See also page 23 of the CAROLINA DROSOPHILA MANUAL.

Fly Generations P1: Parental Generation (parents) F1: First Filial Generation (kids) F2: Second Filial Generation (grandkids) Based on Mendelian Inheritance Patterns you should be able to predict the genotypic & phenotypic ratios of the F1 & F2 offspring. Set up a Punnett Square

Examples to try on the board: P1 generation: You cross (+,+) females X (ap, ap) males P1 generation: You cross (X+,Y) males X (Xw, Xw) females What are the predicted genotypic & phenotypic ratios of the F1 generation? (pages 9 & 10) One step further: What are the predicted genotypic & phenotypic ratios of the F2 generation?

Punnett Squares – F1 & F2 predictions, Wing Mutants P generation: +,+ x ap,ap Wing mutation

+

ap

ap

+ ap

+ ap

F1 generation: +,ap x +,ap Wing mutation

+

+

++

F1’s +

+ ap

ap

+ ap F2’s

+ ap

F1 generation= Genotypic ratio: 100 % (+, ap) Phenotypic ratio: 100% winged

ap

+ ap

ap ap

F2 generation= Genotypic ratio: 1 (+,+) : 2 (+,ap) : 1 (ap, ap) Phenotypic ratio: 3 winged : 1 wingless

Punnett Squares – F1 & F2 predictions, White-Eyed Mutants P generation: XwXw x X+Y Eye mutation

Xw

X+

Y

X+Xw

X+Xw

F1 generation: XwX+ x XwX+ Eye mutation

X+

Xw X+Xw

X+Xw

X+Xw

F1 generation= Genotypic ratio: 1 X+Xw : 1 Xw Y Phenotypic ratio: 100% females red-eyed; 100% males white-eyed

X +Y

F2’s

F1’s Xw

Y

Xw

XwXw

XwY

F2 generation= Genotypic ratio: 1 (X+Xw) : 1 (XwXw) : 1 (X+ Y) : 1 (Xw Y) Phenotypic ratio: 1 red-eyed female : 1 white-eyed female : 1 red-eyed male : 1 white-eyed male

Today’s General Plan: •Get to know your fly babies! •A. •B. •C. •D.

Observe wild-type, apterous & white-eyed phenotypes. Observe Life Stages (have instructor sign-off), page 7 Observe males & females. Count flies in 1 vial. Record observations & data in lab packet, page 7

•Predict F1 offspring:

•A. Set up P1 x P1 Punnett Squares, pages 9 & 10

NEXT WEEK! • QUIZ #1 on this lab material.

• Lab #3: Human Inherited Traits • Check Fly Matings – Clear/Re-do P1 x P1 Matings