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In genetics, a maternal effect occurs when the phenotype of an organism is determined by the genotype of its mother. [1] For example, if a mutation is maternal effect recessive, then a female homozygous for the mutation may appear phenotypically normal, however her offspring will show the mutant phenotype, even if they are heterozygous for the mutation.
One of the best understood examples of pattern formation is the patterning along the future head to tail (antero-posterior) axis of the fruit fly Drosophila melanogaster. There are three fundamental types of genes that give way to the developmental structure of the fly: maternal effect genes, segmentation genes, and homeotic genes.
Maternal effect dominant embryonic arrest (Medea) is a selfish gene composed of a toxin and an antidote. A mother carrying Medea will express the toxin in her germline, killing her progeny. If the children also carry Medea , they produce copies of the antidote, saving their lives.
Hunchback is a maternal effect and zygotic gene expressed in the embryos of the fruit fly Drosophila melanogaster.In maternal effect genes, the RNA or protein from the mother’s gene is deposited into the oocyte or embryo before the embryo can express its own zygotic genes.
The gap genes code for transcription factors that regulate the expression of pair-rule genes and homeotic genes [8] by competing for binding to their enhancer regions. It has been demonstrated that gap gene expression in the Drosophila blastoderm exhibit a property called canalization, a property of developing organisms to produce a consistent phenotype despite variations in genotype or ...
Underdominance of the locus is another possibility of phenotypic expression. Both maternal and paternal phenotypes will have a small value rather than one hosting a large value and silencing the other. Statistical frameworks and mapping models are used to identify imprinting effects on genes and complex traits.
Here are some Mandela effect examples that have confused me over the years — and many others too. Grab your friends and see which false memories you may share. 1.
For example, high concentrations of one maternal protein and low concentrations of others will turn on a specific set of gap or pair-rule genes. In flies, stripe 2 in the embryo is activated by the maternal proteins Bicoid and Hunchback, but repressed by the gap proteins Giant and Kruppel.