多倫多大學(xué)的進(jìn)化生物學(xué)家已經(jīng)發(fā)現(xiàn),，劣質(zhì)基因個(gè)體可能產(chǎn)生更劣質(zhì)染色體的后代，可能導(dǎo)致世代中某些物種滅絕,。
此研究發(fā)表在PNAS上，指出：相對(duì)于高質(zhì)量基因個(gè)體來說，遺傳缺陷生物可能經(jīng)歷DNA突變量增加,。該研究以果蠅為研究對(duì)象，因?yàn)楣壍暮唵蜗到y(tǒng)是更復(fù)雜系統(tǒng)中生物學(xué)諸多方面的模仿,，因此,，此研究發(fā)現(xiàn)可能對(duì)人類有所啟發(fā)。
在此研究中,，研究人員檢測了黑腹果蠅的基因突變累積,，這些基因排列在3個(gè)主要染色體上。為了操控基因質(zhì)量，果蠅三號(hào)染色體被引入有害突變,，以便觀察這些突變的存在如何影響2號(hào)染色體在46代內(nèi)的適應(yīng)性,。結(jié)果是，劣質(zhì)基因提高了突變率,。
盡管還不清楚這種現(xiàn)象所含的機(jī)制,，但這可能與受影響個(gè)體低DNA修復(fù)能力或高DNA易損性有關(guān)。對(duì)于遺傳學(xué)研究,，果蠅尤其有用,，因?yàn)榭捎贸汕先f果蠅篩查成千上萬的基因，飼養(yǎng)費(fèi)用低,，繁殖快,，只在幾個(gè)月內(nèi)就有幾代果蠅可供研究。值得注意的是,，在遺傳學(xué)壓力或環(huán)境壓力的情況下,，升高的突變率也可能加速適應(yīng)新環(huán)境。（生物谷bioon.com）
doi:10.1073/pnas.1118918109
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PMID:
Evidence for elevated mutation rates in low-quality genotypes
N. P. Sharp, A. F. Agrawal
The deleterious mutation rate plays a key role in a number of important topics in biology, from mating system evolution to human health. Despite this broad significance, the nature and causes of variation in mutation rate are poorly understood, especially in multicellular organisms. We test whether genetic quality, the presence or absence of deleterious alleles, affects the mutation rate inDrosophila melanogaster by using a modified mutation accumulation approach. We find evidence that genotypes constructed to carry deleterious "treatment" alleles on one chromosome during mutation accumulation experience an elevated mutation rate on a different chromosome. Further, this elevation is correlated with the effect of the treatment alleles on phenotypic condition, measured as body mass. Treatment alleles that reduce mass by 10% cause a doubling in the rate of mutational decline. Our results show that mutation rates are sensitive to genetic stress, such that individuals with low-quality genotypes will produce offspring of even lower genetic quality, in a mutational positive feedback loop. This type of variation in mutation rate is expected to alter a variety of predictions based on mutation load theory and accelerate adaptation to new environments. Positive mutational feedback could affect human health by increasing the rate of germline mutation, and possibly somatic mutation, in individuals of poor health because of genetic or environmental stress.
