User:Ecstaticreader/sandbox
In peppered moths, the allele for dark-bodied moths is dominant, while the allele for light-bodied moths is recessive, meaning that the typica moths have a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele), and never in a heterozygous one. This helps explain how dramatically quickly the population changed when being selected for dark colouration.[citation needed]
The peppered moth Biston betularia is also a model of parallel evolution in the incidence of melanism in the British form (f. carbonaria) and the American form (f. swettaria) as they are indistinguishable in appearance. Genetic analysis indicates that both phenotypes are inherited as autosomal dominants. Cross hybridizations indicate the phenotypes are produced by isoalleles at a single locus.[1]
The gene for carbonaria in B. betularia was thought to be in a region of chromosome 17, but it was later concluded that it could not contain it because none of the genes in the chromosome coded for either wing pattern or melaninization.[2][3] The region that was used to find it was the first intron of the orthologue of the cortex gene in Drosophila. Through elimination of candidates within the region based on rarity, a 21,925 base pair insert remained.[3]
The insert, labeled carb-TE, is a class II transposable element that has an approximately 9-kb non-repetitive sequence that is tandemly repeated two and a third times.[3] There are 6 base pairs of inverted repeats and duplicated 4 base pairs at the target site that is not present in typica moths. Carb-TE has higher expression during the stage of rapid wing disc morphogenesis.[3] The mechanism of how it increases expression or if it is the only gene involved is still not known.[3]
The pseudogenes found in bacteria like Mycobacterium laprae are usually related to metabolism, but it can also include those involved in DNA processes. There is not an order to which functional genes are lost. For example, the oldest pseudogenes in Mycobacterium laprae are RNA polymerases and the biosynthesis of secondary metabolites while the oldest ones in Shigella flexneri and Shigella typhi are in DNA replication, recombination, and repair[4].
 | This is a user sandbox of Ecstaticreader. You can use it for testing or practicing edits. This is not the place where you work on your assigned article for a dashboard.wikiedu.org course. Visit your Dashboard course page and follow the links for your assigned article in the My Articles section. |
The relationship between epistasis was observed in relation to the domino theory of gene loss. The domino theory suggests that if one gene of a cellular process becomes inactivated, then selection in other genes involved relaxes, leading to gene loss[4]. When comparing Buchnera aphidicola and Escherichia coli, it was found that positive epistasis furthers gene loss while negative epistasis hinders it[5].
- ^ Grant, B. S. (2004). "Allelic melanism in American and British peppered moths". Journal of Heredity. 95 (2): 97–102. doi:10.1093/jhered/esh022. PMID 15073224.
- ^ van't Hof, Arjen E.; Edmonds, Nicola; Dalikova, Martina; Marec, Frantisek; Saccheri, Ilik J. (20 May 2011). "Industrial Melanism in British Peppered Moths Has a Singular and Recent Mutational Origin". Science. 332: 958–960 – via JSTOR.
- ^ a b c d e van't Hof, Arjen E.; Campagne, Pascal; Rigden, Daniel J.; Yung, Carl J.; Lingley, Jessica; Quail, Michael A.; Hall, Neil; Darby, Alistair; Saccheri, Ilik J. (2 June 2016). "The industrial melanism mutation in British peppered moths is a transposable element". Nature. 534: 102–117. doi:10.1038/nature17951.
- ^ a b Dagan, Tal; Blekhman, Ran; Graur, Dan (19 October 2005). "The "Domino Theory" of Gene Death: Gradual and Mass Gene Extinction Events in Three Lineages of Obligate Symbiotic Bacterial Pathogens". Molecular Biology and Evolution. 23: 310–316.
- ^ Martinez-Cano, David J; Bor, Gil; Moya, Andres; Delaye, Luis (29 May 2018). "Testing the Domino Theory of Gene Loss in Buchnera aphidicola: The Relevance of Epistatic Interactions". Life. 8: 1–14.