Епигенетика

[Херцег]

Најновија истраживања из епигенетике показују да околина има огроман утицај на гене, па и да ми нашим свакојаким понашањем-њима, итекако утичемо на нашу будућу децу ...

''Очеви једоше кисело грожђе, а синовима трну зуби''!

погледајте:

http://www.tvo.org/TVO/WebObjects/TVO.woa?videoid?762712642001

[Баба]

[Јован Чакарески]

Pa da, Profesorica genetike (biologije) objašnjavala nam je da ako uzmemo 2 jednojajčana blizanca i jednog odnesemo da živi na selo a drugog u nekom gradu i ako ih posle 20 godina sretnemo oni uopšte neće ličiti jednog na drugog. Naravno ovde nemislim na fizičkog izgleda nego na psihološkom planu, potpuno suprotne osobineće se razviti kod jednog i kod drugog blizanca iako su jedno jajčana.

Genetika je čudo.

[Zayron]

Pa da, Profesorica genetike (biologije) objašnjavala nam je da ako uzmemo 2 jednojajčana blizanca i jednog odnesemo da živi na selo a drugog u nekom gradu i ako ih posle 20 godina sretnemo oni uopšte neće ličiti jednog na drugog. Naravno ovde nemislim na fizičkog izgleda nego na psihološkom planu, potpuno suprotne osobineće se razviti kod jednog i kod drugog blizanca iako su jedno jajčana.

Genetika je čudo.

Tačno, kad imaš jednojajčanog brata a on ti ide tako na ganglije da bi ga najrađe odmah

prodao u roblje na internetovoj aukciji onda tu mnogo ni genetika ne pomaže, hahahaha!

crvenilo

[ego]

Obesity, Epigenetics, and Gene Regulation

Our genome contains all the information to make us who we are, but many of the details of our behavior and appearance are actually determined by gene regulation. A striking example of the power of gene regulation is seen in agouti mice, in which genetically identical twins can look entirely different in both color and size. For example, one mouse may be small and brown, but her twin sister may be obese and yellow. Another genetically identical sister may have a mottled look with both fur colors present and fall in the middle of the weight range. The genome of each of these mice is the same, but the gene expression obviously differs (Figure 1; Duhl et al., 1994).

In these mice, the epigenome is what makes the difference. Picture a network of molecules that are intimately intertwined with nuclear DNA and that have the power to silence genes. The behavior of this entourage of molecules can be altered by the environment (or "nurture," to use the terminology of the classic "nature versus nurture" debate) and can have a profound effect on an individual's phenotype.

For instance, in normal, healthy mice, the agouti genes are kept in the "off" position by the epigenome, which attaches methyl groups to the corresponding regions of DNA, resulting in the DNA's compaction to prevent transcription. In yellow and/or obese mice, however, the same genes are not methylated; thus, these genes are expressed or "turned on." The turning on of this single gene results in an apparent freak of nature. Mice whose agouti gene is "on" are also more likely to suffer from diabetes and cancer as adults.

FIgure 1: Genetically identical, epigenetically different

These three mice are genetically identical. Epigenetic differences, however, result in vastly different phenotypes.

http://www.nature.com/scitable/topicpage/obesity-epigenetics-and-gene-regulation-927

DNA Is Not Destiny

The new science of epigenetics rewrites the rules of disease, heredity, and identity.

Back in 2000, Randy Jirtle, a professor of radiation oncology at Duke University, and his postdoctoral student Robert Waterland designed a groundbreaking genetic experiment that was simplicity itself. They started with pairs of fat yellow mice known to scientists as agouti mice, so called because they carry a particular gene—the agouti gene—that in addition to making the rodents ravenous and yellow renders them prone to cancer and diabetes. Jirtle and Waterland set about to see if they could change the unfortunate genetic legacy of these little creatures.

Typically, when agouti mice breed, most of the offspring are identical to the parents: just as yellow, fat as pincushions, and susceptible to life-shortening disease. The parent mice in Jirtle and Waterland's experiment, however, produced a majority of offspring that looked altogether different. These young mice were slender and mousy brown. Moreover, they did not display their parents' susceptibility to cancer and diabetes and lived to a spry old age. The effects of the agouti gene had been virtually erased.

Remarkably, the researchers effected this transformation without altering a single letter of the mouse's DNA. Their approach instead was radically straightforward—they changed the moms' diet. Starting just before conception, Jirtle and Waterland fed a test group of mother mice a diet rich in methyl donors, small chemical clusters that can attach to a gene and turn it off. These molecules are common in the environment and are found in many foods, including onions, garlic, beets, and in the food supplements often given to pregnant women. After being consumed by the mothers, the methyl donors worked their way into the developing embryos' chromosomes and onto the critical agouti gene. The mothers passed along the agouti gene to their children intact, but thanks to their methyl-rich pregnancy diet, they had added to the gene a chemical switch that dimmed the gene's deleterious effects.

With no more than a change in diet, laboratory agouti mice (left) were prompted to give birth to young (right) that differed markedly in appearance and disease susceptibility.

"It was a little eerie and a little scary to see how something as subtle as a nutritional change in the pregnant mother rat could have such a dramatic impact on the gene expression of the baby," Jirtle says. "The results showed how important epigenetic changes could be."

http://discovermagazine.com/2006/nov/cover