2 30 4 25 Wednesday Biology 1103 Lab Group Wil Buchanan Whitney Boozer 2009 2010 Term C elegans have been organisms in science known to uncover the many secrets of some of the most basic cellular processes in animals Some of the uses of C elegans in science include research on embryonic development sex development sex determination aging and alcoholism laboratory manual sixth ed Some reasoning behind the effectiveness of C elegans in this research is their versatility The species C elegans are usually hermaphrodites meaning they make both eggs and sperm Another unique aspect is their ability to reproduce by either self fertilization or mating with a male C elegans are harmless round worms but they can often be mistaken for vicious bloodsucking parasites When viewing C elegans some telltale characteristics one can look for is their long slim physique with females differing in their feathered off wispy tail compared to the fat bulb of the male The females other known as hermaphrodites with their androgynous characteristics often move slower than the males who speed swiftly under the lens of a high powered microscope There can be several types of C elegans varying from mutant females coupled with the wild type males and females The male species is often seemingly outnumbered by the amount of females resulting from the female s ability to self produce and mutate with various species When establishing a cross between organisms once must first consider many things The projected outcome of the cross must be taken into account as well as the status of the organism for example whether it is mutated or normal If mutated it is also important to evaluate the source of the mutation assessing its dominance or recessiveness and deciphering whether the disease is sex linked resulting from the female chromosome or from one of the other twenty two autosomal chromosomes When approaching our scientific cross my lab partner and I aimed especially to further investigate mutations in C elegans Our first inquiry was to find out if the mutation in the hermaphrodite of question was sex linked or autosomal Sex linked genes are the phenotypic expression of an allele that is related to the chromosal sex of the individual The most telltale sign in concluding if the gene is x linked recessive or not is if the son has the defective gene resulting in a mutation Because the gene is recessive it is usually up to the son to detect the gene because he will pick up a defective x from the mother and a y from the father Girls have the beneficial circumstance of having a backup x from the mother that often results in them not receiving the mutation Autosomal recessive on the other hand depends on the genotype of both parents Because of this both parents must be carrier s for the gene in order for the mutation to be expressed in the offspring A carrier simply means that each parent contains the recessive allele for the mutation This usually does not mean that they have the mutation only the fact that they have a strong chance of transferring the mutation to their offspring XhX Sex linked x XY Xh X Y XhX XhY X XX XY XhX x XhY Autosomal Xh Xh Y Xh Xh XhY Vs X XhX XY For our mutation our group decided to pick a C elegan known as dpy 5 Its characteristics differing from normal wild type worms are largely due to dpy 5 s short and fat physique Initially we projected that the mutation in question would be autosomal and that the mutated dpy 5 contained the dominant allele If this were to be the case our cross of the mutated dpy 5 with a normal wild type male would produce one hundred percent mutated hermaphrodites since the trait was dominant over the recessive wild type allele Our projected cross D mutated allele x d normal wild type allele D D d Dd Dd d Dd Dd Key DD mutated dpy 5 is dominant therefore results 100 mutation After procuring two crosses to produce the most efficient results we found the info to be much different from what we expected This is the information we received Cross 1 Cross 2 Mutated Male 0 Normal Wild type 24 Male Mutated Hermaphrodite 20 Normal Wild type Hermaphrodite 57 Mutated Male 0 Normal Wild type Male 21 Mutated Hermaphrodite 34 Normal Wild type Hermaphrodite 49 From these results we could infer that our entire initial hypothesis was proven false Before the experiment our group anticipated offspring that would reflect a dominant mutation and all offspring would receive the mutated allele but surprisingly enough these expectations were mistaken Based on these results it is apparent that the dpy 5 allele is recessive Because of this allele s autosomal recessive characteristics our experiment resulted in no mutated males and a plethora of wild type male and hermaphrodites When analyzing these results we could conclude that the mutation was not sex linked because none of the male received the mutation Even though the male had the normal healthy y chromosome a defective x chromosome from the mother should have produced at least of few mutated males as a result Essentially we can also rule out the dominance of the allele because the offspring do not show a dominance of the mutation We know from the data that none of the males displays this gene but what about the hermaphrodites one may ask Well we know that hermaphrodites are unique in stature Unlike the normal males they have the ability to produce eggs and sperm as well as self fertilize Because of this knowledge we can critically assess the information and expertly infer that the resulting mutated hermaphrodites occurred only because of their self fertilization abilities