Species and Speciation s1

Getting to know Drosophila melanogaster: Teacher’s Notes

Purpose: Drosophila melanogaster, also known as the fruit fly, is a popular model organism in the fields of genetics and developmental biology. Many important discoveries of genetic and chromosomal inheritance were made through the use of fruit flies. The basic genetic principles in the fruit fly can also be applied to humans. Scientist continue to study Drosophila to better understand growth, development, and diseases in humans. The goal of this lesson is to familiarize students with Drosophila to learn genetics.

At the end of this lesson, students should be able to: 1. Understand the reproduction and life cycle of Drosophila melanogaster. 2. Learn to sex and identify virgin flies, which are important for setting up crosses. 3. Understand Mendelian genetics and inheritance of traits. Interpret and analyze data. 4. Understand that mutations in a DNA sequence may affect the expression of genes. 5. Understand that all cells in a multicellular organism have identical DNA but that genes are expressed differently resulting in different cell types that have different functions.

CA Science Content Standards: 7th Grade Life Science Subject Standards Addressed

1.a: Students know cells function similarly in all living organisms. 1.e: Students know cells divide to increase their numbers through a process of mitosis, which results in Cell Biology two daughter cells with identical sets of chromosomes. 1.f: Students know that as multicellular organisms develop, their cells differentiate. 2.a: Students know the differences between the life cycles and reproduction methods of sexual and asexual organisms. 2.b: Students know sexual reproduction produces offspring that inherit half their genes from each parent. 2.c: Students know an inherited trait can be determined by one or more genes. Genetics 2.d: Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive. 2.e: Students know DNA (deoxyribonucleic acid) is the genetic material of living organisms and is located in the chromosomes of each cell. 3.a: Students know both genetic variation and environmental factors are causes of evolution and Evolution diversity of organisms. 7.a: Select and use appropriate tools and technology to perform tests, collect data, and display data. 7.b: Use a variety of print and electronic resources to collect information and evidence as part of a Investigation & research project. Experimentation 7.c: Communicate the logical connection among hypotheses, science concepts, tests conducted, data collected, and conclusions drawn from the scientific evidence. 7.d: Construct scale models, maps, and appropriately labeled diagrams to communicate scientific knowledge. 7.e: Communicate the steps and results from an investigation in written reports and oral presentations.

1 CA Science Content Standards: High School

Subject Standards Addressed 1.a: Students know cells are enclosed within semi-permeable membranes that regulate their interaction with their surroundings. 1.c: Students know how prokaryotic cells, eukaryotic cells and viruses differ in complexity and general Cell Biology structure. 1.d: Students know the central dogma of molecular biology outlines the flow of information from transcription of ribonucleic acid (RNA) in the nucleus to translation of proteins on ribosomes in the cytoplasm. 2.a: Students know meiosis is an early step in sexual reproduction in which the pairs of chromosomes separate and segregate randomly during cell division to produce gametes containing one chromosome of each type. 2.b: Students know only certain cells in a multicellular organism undergo meiosis. 2.c: Students know how random chromosome segregation explains the probability that a particular allele will be in a gamete. 2d: Students know new combinations of alleles may be generated in a zygote through the fusion of male and female gametes (fertilization). 2e: Students know why approximately half of an individual’s DNA sequence comes from each parent. 2f: Students know the role of chromosomes in determining an individual’s sex. 2g: Students know how to predict possible combinations of alleles in a zygote from the genetic makeup of the parents. Genetics 3.a: Students know how to predict the probable outcome of phenotypes in a genetic cross from the genotypes of the parents and mode of inheritance (autosomal or X-linked, dominant or recessive). 3.b: Students know the genetic basis for Mendel’s laws of segregation and independent assortment. 4.c: Students know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in an encoded protein. 4.d: Students know specialization of cells in multicellular organisms is usually due to different patterns of gene expression rather than to differences of the genes themselves. 5.a: Students know the general structures and functions of DNA, RNA, and protein. 5.c: Students know how genetic engineering (biotechnology) is used to produce novel biomedical and agricultural products. 5.e: Students know how exogenous DNA can be inserted into bacterial cells to alter their genetic makeup and support expression of new protein products. 7.a: Students know why natural selection acts on the phenotype rather than the genotype of an organism. Evolution 7.b: Students know why alleles that are lethal in a homozygous individual may be carried in a heterozygote and thus maintained in a gene pool. 7.c: Students know new mutations are constantly being generated in a gene pool. 1.a: Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data. 1.c: Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions. 1.d: Formulate explanations by using logic and evidence. Investigation & 1.g: Recognize the usefulness and limitations of models and theories as scientific representations of Experimentation reality. l.l: Analyze situations and solve problems that require combining and applying concepts from more than one area of science. 1.m: Investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings.

2 Instructions: Please refer to ‘Using Drosophila melanogaster in middle and high school classrooms’ written by Molly Burke for instructions on how to handle, feed, obtain, and maintain Drosophila melanogaster stocks.

Preparation Timeline: Day of Lesson/Activity Preparation instruction  Flies need to be cultured 15 days prior to day of instruction in order to have all the Introduction to Drosophila life cycle different stages of Drosophila development. 1 lesson/ Identify the different stages of See instructions below. Drosophila development activity  On the day of activity, set up student work stations.  Two days prior to activity prepare vials that Identify male versus female flies will be used by students. See instructions 2 lesson/ Identify male versus female below. flies activity  On the day of activity, set up student work stations.  Teacher should start virgin collection a week Introduction to fruit fly genetics prior to part I of activity. 3 lesson/ Flying through genetics part I  On the day of activity, set up student work stations.  Perform this activity two weeks after part I. 4 Flying through genetics part II  On the day of activity, set up student work stations.  Teacher should start virgin collection three weeks prior to activity. Gene expression, function, and  Teachers should set up crosses two weeks 5 regulation lesson/ Gene expression, prior to lab activity. See instructions below. function, and regulation activity  On the day of activity, set up student work stations.

Instructions:

Station1 (Identify the different stages of Drosophila development): Materials:  A mature Drosophila stock (vendors or university lab).  Vials with fly food and cotton. You can make your own or purchase from Developmental Biology Center at UCI (100 small vial for ~$22).  Dissecting scope.  Small petri cultures with apple agar. You can use orange or grape juice as well.

3 Preparing the apple juice agar medium Heat 1 liter apple juice to a slow boil. Add 15 g agar until dissolved. Pour 20-25mL agar into small plates. Use sterile technique.

Preparation Notes:

1. Flies need to be cultured 15 days prior to day of instruction in order to have all the different stages of Drosophila development.

2. The day prior to lab activity, select and label the Drosophila cultures with adults, pupa, and larva.

3. For the egg container, place mated females in a Petri dish prepared with apple juice agar medium while they are asleep. Leave the females in the petri dish for 1 day at room temperature. During this time they will lay eggs. The morning of activity, release the adult females. Students will be able to observe eggs on the plates.

Station 2 (Identify males versus females): Materials:  A mature Drosophila stock.  Vials with fly food and cotton.  FlyNap  Paint brush

Preparation Notes: 1. Two day prior to lab activity, separate males and females from a Drosophila stock. 2. Place 10 females and 10 males in each vial.

Station 3(Flying through genetics): Materials:  Two mature Drosophila stocks. One must have Curly wings (CyO) and the other can be a wild-type stock like Canton-S or Oregon-R with straight wings.  Vials with fly food and cotton. FlyNap  Petri dish  Paint brush

4 Preparation Notes:

1. Teacher should collect virgin females. Carolina sells heat shock stocks that make virgin collection easier.

2. For this activity I collected virgin females from the wild-type stock and used curly wing males. Station 4 (Gene expression, function, and regulation) Materials:  Six mature Drosophila stocks.

1 Canton-S 2 w[*]; wg[Sp-1]/CyO; P{w[+mW.hs]=GAL4-dpp.blk1}40C.6/TM6B, Tb[1] 3 y[1] w[*]; P{w[+mC]=UAS-ey.H}UE11 4 sv[de]/Dp(2;4)ey[D], Alp[eyD]: ey[D] 5 ci[1] ey[R] sv[n] 6 ey[2]

 Vials with fly food and cotton (you can make you own or purchase from Developmental)  FlyNap  Paint brush  Fine foreceps

Preparation Notes: 1. Collect virgins three weeks prior to activity. 2. Set up the following crosses with 5 virgin females and 5 males. Stock A x Stock B. Cross Stock A (virgin Stock B (males) Notes females) 1. Canton S Canton S  Wild-type culture used as control.

2a. sv[de]/Dp(2;4)ey[D], ey[2]  F1 generation will Alp[eyD]: ey[D] Bloomington #648 have small eyes Bloomington #662 or no eyes no eyes.

2b. sv[de]/Dp(2;4)ey[D], ci[1] ey[R] sv[n]  F1 generation will Alp[eyD]: ey[D] Bloomington #639 have small eyes Bloomington #662 or no eyes no eyes.

2c. ey[2] ci[1] ey[R] sv[n]  F1 generation will have small eyes

5 Bloomington #648 Bloomington #639 or no eyes no eyes.

3 y[1] w[*]; w[*]; wg[Sp-1]/CyO;  F1 generation will P{w[+mC]=UAS- P{w[+mW.hs]=GAL4- have extra eyes. ey.H}UE11 dpp.blk1}40C.6/TM6B, Tb[1] Bloomington #6294 Bloomington #1553

3. Teachers should collect F1 flies displaying phenotypes and prepare vials for students a day or two prior to activity.

4. F1 generation with phenotype from cross 3 will die in the pupal case. Use forceps to remove the pupal case. Store in acetone until ready for use. Purchasing Guide*: Vendor Item Description Catalog # Unit Unit Cost Drosophila Monohybrid Cross Kit (with Carolina 171984 each $81.95 Prepaid Coupon) Carolina Drosophila Culture Kit 173050 each $56.50 173010 $12.50 Carolina Fly Nap Anesthetic kit Box Carolina Easy Fly Drosophila Cultures, Carolina 172632 1 vial $18.95 wild type (Oregon-R with hsY) Drosophila, Living, Curly/Plum(2); Carolina Dichaete/Stubble(3), Multichromosomal 172750 1 vial $6.95 Mutant Bloomington 1 Drosophila 1 vial Stock Center Canton-S $15 (BDSC) BDSC y[1] w[*]; P{w[+mC]=UAS-ey.H}UE11 6294 1 vial $15 BDSC sv[de]/Dp(2;4)ey[D], Alp[eyD]: ey[D] 662 1 vial $15 BDSC ey[2] 648 1 vial $15 BDSC ci[1] ey[R] sv[n] 639 1 vial $15 BDSC W[*]; wg[Sp-1]/CyO; P{w[+mW.hs]=GAL4- 1553 1 vial dpp.blk1}40C.6/TM6B, Tb[1] $15 UCI Fly food and cotton 100 vials of Dev Bio $22.00 food vials Center Fisher Scientific Petri dishes with clear lids (500) 08-757-13 case of 500 $49.63 Fisher Fisherbrand* Extra-Deep Disposable Petri Scientific Dishes 08-757-11 case of 500 $109.69

6 Fisher Fisherbrand* Dissecting Extra-Fine-Pointed 13-812-42 case of 4 $42.40 Scientific Splinter Forceps

References:

 Bloomington Drosophila Stock Center at Indiana Universityhttp://flystocks.bio.indiana.edu/  Burk, Molly. ‘Using Drosophila melanogaster in middle and high school classrooms’ Available at: http://www.bio.uci.edu/academic/grad/GK- 12/Lessons.shtm#DaphBurke  Flybase: http://flybase.org/  UCI Developmental Biology Center: http://dbc.bio.uci.edu/