Genetic - Mapping of a Gene Causing a Drosophila Mutant Phenotype - Lab Report Example

TASK PAGE GENETIC -MAPPING OF A GENE CAUSING A DROSOPHILA MUTANT PHENOTYPE. The genetic mapping experiment, took into consideration the use of a Wrinkled mutant Drosophila and eleven other strains of the Drosophila with different features.The rationale behind this experiment was to establish the location of the gene underlying the Wrinkled mutant phenotype on a Drosophila melanogaster genetic map.The experiment was performed in a laboratory setting with food and temperature of 28-30 degrees Celsius. Therefore, the principle component of this paper is the exploration of the genetic mapping of the fruit fly vis-à-vis gene mutation and recombination in the chromosomal sites. Additionally, the determination of sex linkage and autosomal mutations is primary. ABSTRACT Statement of study objective. Determination of the genetic mapping and location of wrinkled genes, in a Drosophila fruit fly experiment. The importance of this experimental study cannot be disregarded. This is because of its scientific weight to researchers about solving life challenges of human beings that revolve around the DNA structure and composition. In brief the fundamental materials that were used in the study include the wrinkled mutant fruit fly, eleven other mutant strains and laboratory equipment, i.e. CO2 Tank and controller, vials, foodstuffs, dried yeast, dispensing jar, dissembler microscopes, paint brushes, forceps, sharpies sorting boxes and fly morgue. From the experiment, it is evident that, ten genes are available in the region. Under the associated gene name, the gene represented by wrinkled gene w is not present based on the results from the BLAST link provided. It is therefore found outside the genus Drosophila. The starting hypothesis is, therefore, rejected. It is prominent that the most unexpected thing occurred in the experimental results. The fact that the gene location of W that was under investigation was not available from the genome database indicates that the identical chromosomes of the Drosophila fruit fly would theoretically never recombine. This is predominantly because, the diploid characteristic of chromosomes permits for genes on dissimilar chromosomes to separate, independently or be separated from their homologous pair throughout sexual reproduction in which haploid gametes are produced. INTRODUCTION Drosophila melanogaster is a variety of fly in the taxonomic order Diptera, family Drosophilidae. It is commonly referred to as fruit fly. It is a biological research model in the diverse fields ranging from heredity studies, physiological studies, and microbial pathogenesis to life account evolution. This species of fly is preferred by researchers because it is easy to maintain, has four pairs in terms of chromosomal composition, breeds faster due to its characteristic shorter lifespan and it possesses higher fecundity levels. Thus, the essence of this paper is to explore the genetic mapping of the fruit fly concerning gene mutation and recombination in the chromosomal sites. Additionally, the determination of sex linkage and auto somatic linkage are ideally fundamental (Alice, 2). The Drosophila fruit fly (melanogaster) has a diminutive lifespan of approximately 30 days. This lifespan can however be increased depending on the temperature levels by 28-29 degrees Celsius temperature being most favorable. Drosophila is extremely beneficial to biological research in that it has a relatively short life cycle. Therefore, scientists can study many generations in a short period. The standard lifespan of drosophila, reminiscent of various other organisms, is reliant on environmental conditions. In a laboratory setting the life span of a drosophila fly, tend to be roughly 26 days for wild-type females to 33 days for wild-type males. Additionally, it is notable that mutant flies will normally have a shorter lifespan. After copulation, a female fly will lay an egg that is approximately 1 mm long. After a period of 1 day, the eggs will hatch and larvae will creep out. The larvae will crawl around in the medium feeding on small microorganisms that result from decomposition of organic matter and then materialize into white-looking organisms. They will undergo rapid development for a phase of four days after hatching, and they experience moulting in about 1 day. After two days as third instars larvae, the larvae will edge up the wall of the vial and will portray an outward appearance of a stationary pupa precisely on the wall. This is the foundation of the pupae stage. Over the subsequent 4-6 days, the majority of the larval tissues will be cracked, and the adult type of the fly will develop. When the pupal stage diminishes, the adult fly materializes from its covering and is productive in a span of about 12 hours In Genetic mapping, genetic markers are frequently used in carrying out experimental research, for instance, for the case of balancer chromosome, most phenotypes are simply identifiable through the eye or by use of a microscope. Thus, markers such as curly wings, eye color, body pigmentation and physique are among those that are commonly employed in genetic studies. In view of the sex-linked traits, fruit flies contain the X and Y-chromosomes that are involved in transfer of characteristics during the process of inheritance. Because of the distinctive similarities with humans in terms of chromosomal composition and genetic makeup, genetic experts to solve problems of sex-linked traits including disputed parentage in humans have used them adversely. In addition, the 75%match of human genealogy within these flies makes disease related problems in man recognizable and solvable. The protein sequence in humans is fundamental in relation to the drosophila genomes. In this regard, diverse categories of diseases ranging from spin cerebellar ataxia, Alzheimer disease, Parkinson’s disease and neurodegenerative disorders have been studied and their results revealed. The study mechanisms underlying oxidative stress, immunity, diabetes, cancer and notably drug abuse are currently in the public domain. Gene mapping in drosophila fruit fly, encompass the laws of genetics, i.e. the law of independent assortment, the law of segregation and the law of dominance. In view of the single most important law in this process, the law of independent assortment forms the foundation of this study. On this note, the diploid characteristic of chromosomes permits for genes on dissimilar chromosomes to separate, independently or be separated from their homologous pair throughout sexual reproduction in which haploid gametes are produced. In this approach, fresh combinations of genes are able to occur in the progeny of a mating duo. Genes on the identical chromosomes would hypothetically never recombine. On the other hand, they do so through the cellular progression of chromosomal crossover. During this crossover, chromosomes swap stretches of DNA, successfully shuffling the genetic material alleles between the chromosomes. This procedure of chromosomal intersection usually occurs in meiosis, in which sequences of cell allotments create haploid cells. The possibility of chromosomal intersection happening between two particular points on the chromosome correlates to the distance linking the points. From a randomly elongated distance, the likelihood of crossover is elevated enough that the inheritance concerning the genes is successfully uncorrelated. For genes that are nearer mutually, however, the smaller prospect of crossover implies that the genes exhibit genetic linkage; alleles of the two genes lean towards being inherited together. The quantity of linkage between a series of genes can combine to figure out a linear linkage map that approximately describes the planning of the genes alongside the chromosome. Thus, this process is central in gene mapping. Mutations that involve genes provide a basic platform as the essential rationale of establishing the gene locations on a genetic map. Mutations are commonly, occasioned by the unwarranted errors that occur in the DNA strand polymerization. They are thus responsible for causing serious impacts on the phenotypic composition of an organism, particularly when they occur inside the protein coding progression of a gene. In organisms that utilize chromosomal crossover to substitute DNA and recombine the genetic material, there is a possibility of occurrence of errors in arrangement during the process of meiosis. This as well contributes to mutational alterations. Additionally, mismatches in intersections are principally probable when analogous sequences render the cohort chromosomes to adopt an erroneous alignment. This results to diverse sections in genomes being susceptible to mutations. The resultant overall effect owing to these facts is enormous structural adjustments in the DNA series. Ranging from duplications, deletions, inversions and chromosomal translocations that primarily form a fertile ground for detailed research in view of the broad genetic study and its relevant applications in daily life situations that endeavor to solve human challenges (Genetic Mapping, 23). Hypothetically, assumption of linkage can be tested statistically by way of comparison in the observed experimental ratios of parental: non-parental fruit flies in the testcross progeny to a 1:1 ratio via chi-square test analysis. For the case of sex linkage: About this experiment, it is fundamental to note that the genes of a Drosophila melanogaster are four pairs. In sex linkage, we consider the X and Y-chromosomes. The X chromosome is responsible for carrying of traits hence in a genetic cross it indicates the phenotypic composition of the flies. In view of the sex-linked traits involving white eyes, consider a cross below A cross between white-eyed female drosophila fly and a normal male fly. A PARENTAL PHYNOTYPE: female with white eyes and a normal male PARENTAL GENOTYPE: XwX w XY GAMETES: Xw X w X Y After fertilization, the resultant F1 offspring are genotypically represented by: XwX : XwX XWY XWY F1 PHENOTYPE: carrier female, carrier female, white eyed male white eyed male This genetic cross indicates that when a drosophila melanogaster is dominant for a certain gene due to mutational variations the F1 off springs that arises have a ratio of 2:2 carrier females: white eyed males. It is however important to note that a carrier female can be phenotypically be represented to be normal but genotypically otherwise. Project methods and materials. The genetic mapping experiment took into consideration: the Wrinkled mutant gene of the Drosophila strain abbreviated as W and flies of eleven other mutant strains of the flies representing different characteristics, i.e. White, singed, Bar, Black, lobe, brown sepia, scarlet, rosy ebony and eyeless strains, each with distinct phenotypes. It is remarkable to note that the crosses to be carried out are meant to ascertain the measurements of recombination of the mutant genes in duos (Davies, and Shirley and Tilghman, 34). Additionally, the F1 females are matched amid males that are homozygous for the recessive alleles at both genes. The table below represents the strains in a tabular form. A tabulated format. Name Symbol Phenotype Inheritance Location White W eyes white recessive, sex-linked 1, 1.5 Singed Sn bristles curly recessive, sex-linked 1, 21 Bar B eyes bar-shaped dominant, sex-linked 1, 57 Black B body black recessive, autosomal 2, 48.5 Lobe L eyes reduced dominant, autosomal 2, 72 Brown Bw eyes brown recessive, autosomal 2, 104.5 Sepia Se eyes sepia recessive, autosomal 3, 26 Scarlet St eyes scarlet recessive, autosomal 3, 44 Rosy Ry eyes dark red recessive, autosomal 3, 52 Ebony E body dark recessive, autosomal 3, 70.7 Eyeless Ey eyes reduced recessive, autosomal 4, 2 Other materials included in the experiment were: Additional Materials: 1. CO2 Tank and controller 2. Unfilled Vials and Plugs 3. Fly rations (flaky material) in Tubs 4. Tagosept in the dispensing jar 5. Dried yeast 6. dismember microscopes with overhead glow 7. Paint brushes 8. Pairs of Forceps 9. Sharpies 10. Box for sorting and or arranging flies 11. Beaker with soapy water to serve as a (fly morgue) Procedure: 1. Acquire 1 vial of wrinkled W from the instructor, and 1 vial of sepia flies (se) and then Set up a cross between approximately five virgin female flies of this strain assigned and approximately five W males. Properly label the vials with all the details. 2. Set up a cross between about five virgin females resulting from the F1 crosses and approximately five males that will be homozygous for the recessive genomes at each of the W gene and the mutant gene of sepia strain. Label the vial. Give any remaining F1 offspring to the instructor. Remove all vials of all adult flies by gassing with CO2 and then moving them from the vial to the fly morgue -beaker of soapy water. 3. After approximately 8-9 hours, gather 5-7 virgin sepia females. Reminder: female flies accumulate the sperm of all the males with which they mate. Therefore, if no waiting for longer periods because females will have already mated, and will no longer be of the essence 4. After about 7 days, eliminate all surviving adult flies from the testcross vial and dispose them off in a fly morgue-beaker with soapy water. 5. After a period of approximately 7 days after step 4, determine the phenotypes mutant or wild-type of both characters for as several testcrosses the off springs as possible. Experimental results From the ensemble link the data results are: Ensembl Gene ID Associated Gene Name FBgn0031208 CG11023 FBgn0002121 l(2)gl FBgn0031209 Ir21a FBgn0263584 CR43609 FBgn0051973 Cda5 FBgn0067779 dbr FBgn0031213 galectin FBgn0031214 CG11374 FBgn0002931 net FBgn0031216 CG11376 2 matches to query [fbgn-SYMBOL:W] Convert to # Symbol Name Annotation ID Cytology Alleles # Stocks # Clones # 1 w  white CG2759 3B6-3B6 2309 81714 5 2 w::Dmau\w w - - 81 - - Dmel\w Species D. melanogaster Name white Annotation symbol CG2759 Feature type protein_coding_gene Fly Base ID FBgn0003996 Gene Model Status Current Stock availability 81714 publicly available Also Known As EG:BACN33B1.1, DMWHITE Genomic Location Cytogenetic map 3B6-3B6 Sequence location X:2,790,599..2,796,466 [-] Genomic Maps Top of Form Decorated FASTA Bottom of Form Top of Form Bottom of Form Families, Domains and Molecular Function W gene is found in the 3B-3B6 cytology. Results. recombinant parental chi-sq. test B 20 16 0.44 se 4 9 1.92 bw 18 22 0.4 ry 1 16 13.2 ey 6 10 1 Our class results combined w. Dr. Stumps class results recombinant parental B 20 16 bw 18 22 ry 1 16 ey 6 10 w 50 46 se 24 58 st 4 32 From the chi –square above, ANALYSIS OF DATA Crossover data are based on statistical samples that include of likely events. The greater number of flies involve in the study, the more likely that the data will display a statistically dependable sample of the crossover frequency that we are studying. For this rationale, it is generally advisable to merge the flies counted by all lab sections in order to have acquired large samples for this calculation. By placing the phenotype, the classes that represent gametes formed by the same crossover event together, and then compute the percentage, with which each pair occurred. These frequencies by themselves yields crossover distances in two point crosses, but a three point cross necessitates for further examination and calculation (Pawlowitzki, Edwards and Thompson, 23). The duo of phenotype classes with the uppermost frequency should symbolize the non-cross-over parental classes. This can be checked these since the genotypes of the mothers of these flies are known. The pair of classes with the minimum frequency should characterize the double crossover classes since we anticipate two crossovers to happen with lower frequency than a single crossover (Genetic Mapping, 23). The two remaining pairs should be the single crossover classes. To establish the gene arrangement, i.e., which gene is in the middle, scrutinizes which gene change places during the comparison regarding the parental combinations to the twofold recombinant groups. The gene that swaps places is the central gene. In conclusion, the genetic mapping of the Drosophila fruit fly establishes the possibilities of combinations in view of the diversity exhibited in the genealogy of the different strains of the fly.This mapping has been employed by scientists in different fields to determine the DNA related complications in human beings. By determining the gene, locations using the protein BLAST program genetic compositions and chromosomal mutation variations have been determined arguably because of the correspondence of the Drosophila genes with the genes in man (Boopathi, 23). Thus, the problems of disputed parentage drug abuse, cancer, immunity and oxidative stress have so far been demystified (Davies and Tilghman, 34). Bottom of Form From the observation of the analysed experimental data it is evident that wrinkled is found outside the genus Drosophila. From the BLAST link Other species that have related features are the Clostridium categories and as well as the Papio anubis Analysis and inferences based on the project results From the link considering Dmel-white, the types of organisms found to contain the protein structure include, Micrococcus spA1, Pseudoateromonas antlatica, Panabacteroides, Citrobactor koseri, Human immunodeficiency virus 1, Streptococcus pneumonia etc. Considering the Dmel-ey link in BLAST, the organisms found to possess the protein structure are among others; Nicotiana tomentosiformis, Pichia kudravzevii, Firmicutes bacterium, etc the hypothesis of his study is to use the patterns of linkage to determine a likely map position for wrinkled. After completion of this positional determination, then we shall identify the genes located In the chromosomal region by employing the genome database for Drosophila melanogaster (Boopathi, 23). However, by use of the BLAST link program, it is fundamental to note that the gene for wrinkle was not identifiable. Therefore, it is clear from the experimental research that the Ho is rejected and the study disaproves the starting hypothesis. It is notable that the most unexpected thing from the experimental results was the fact that the gene location of W that was under investigation was not available from the genome database. From the point of perspective of the independence in the assortment, the identical chromosomes would hypothetically never recombine this is primarily because the diploid characteristic of chromosomes permits for genes on dissimilar chromosomes to separate, independently or be separated from their homologous pair throughout sexual reproduction in which haploid gametes are produced (Boopathi, 23). Work Cited Boopathi, N M. Genetic Mapping and Marker Assisted Selection: Basics, Practice and Benefits. New Delhi: Springer India, 2013. Internet resource. Davies, K E, and Shirley M. Tilghman. Genetic and Physical Mapping. Plainview, N.Y: Cold Spring Harbor Laboratory Press, 2000. Print. Genetic Mapping. S.l.: General Books, 2010. Print. Pawlowitzki, Ivar-Harry, J H. Edwards, and E A. Thompson. Genetic Mapping of Disease Genes. San Diego: Academic Press, 2007. Print. Wexler, Alice. Mapping Fate: A Memoir of Family, Risk, and Genetic Research. New York: Times Books, 1995. Print. Read More