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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.
The data indicated a widening disparity in black-white infant mortality as maternal ages increase. Subsequently, Geronimus proposed the "weathering hypothesis", which she initially conceived as a potential explanation for the patterns of racial variation in infant mortality with increasing maternal age. [11]
Fertility declines have been seen during economic recessions. This phenomenon is seen as a result of pregnancy postponement, especially of first births. But this effect can be short-term and largely compensated for during later times of economic prosperity. [11] Increased unemployment is generally associated with lower fertility. [11]
In plants, POC over the allocation of resources to the brood members may affect both brood size (number of seeds matured within a single fruit) and seed size. [3] Concerning brood size, the most economic use of maternal resources is achieved by packing as many seeds as possible in one fruit, i.e., minimizing the cost of packing per seed.
For both genes, the maternal effect lethality was the basis for the selection of their names. Medea was named for the mythological Greek Medea, who killed her progeny fathered by Jason. Both Medea and Mothers against dpp were identified in a genetic screen for maternal effect mutations that caused lethality of heterozygous decapentaplegic ...
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.
The maternal effect genes are responsible for the polarity of the egg and of the embryo. The developing egg ( oocyte ) is polarized by differentially localized mRNA molecules. The genes that code for these mRNAs, called maternal effect genes , encode for proteins that get translated upon fertilization to establish concentration gradients that ...
The effect of shared environment, c 2, contributes to similarity between siblings due to the commonality of the environment they are raised in. Shared environment is approximated by the DZ correlation minus half heritability, which is the degree to which DZ twins share the same genes, c 2 =DZ-1/2h 2.