Freud contra Darwin! Epigenetica!

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Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 06 Ene 2014 12:34

No solo importan los genes, nuestros actos, forma de vida etc... inluyen en que genes se activan y cuales no:

Your ancestors' lousy childhoods or excellent adventures might change your personality, bequeathing anxiety or resilience by altering the epigenetic expressions of genes in the brain.

Since the 1970s, researchers had known that the tightly wound spools of DNA inside each cell’s nucleus require something extra to tell them exactly which genes to transcribe, whether for a heart cell, a liver cell or a brain cell.

One such extra element is the methyl group, a common structural component of organic molecules. The methyl group works like a placeholder in a cookbook, attaching to the DNA within each cell to select only those recipes — er, genes — necessary for that particular cell’s proteins.

Originally these epigenetic changes were believed to occur only during fetal development. But pioneering studies showed that molecular bric-a-brac could be added to DNA in adulthood, setting off a cascade of cellular changes resulting in cancer. Sometimes methyl groups attached to DNA thanks to changes in diet; other times, exposure to certain chemicals appeared to be the cause. Szyf showed that correcting epigenetic changes with drugs could cure certain cancers in animals.

Geneticists were especially surprised to find that epigenetic change could be passed down from parent to child, one generation after the next. A study from Randy Jirtle of Duke University showed that when female mice are fed a diet rich in methyl groups, the fur pigment of subsequent offspring is permanently altered. Without any change to DNA at all, methyl groups could be added or subtracted, and the changes were inherited much like a mutation in a gene.

Now, at the bar in Madrid, Szyf and Meaney considered a hypothesis as improbable as it was profound: If diet and chemicals can cause epigenetic changes, could certain experiences — child neglect, drug abuse or other severe stresses — also set off epigenetic changes to the DNA inside the neurons of a person’s brain? That question turned out to be the basis of a new field, behavioral epigenetics, now so vibrant it has spawned dozens of studies and suggested profound new treatments to heal the brain.

According to the new insights of behavioral epigenetics, traumatic experiences in our past, or in our recent ancestors’ past, leave molecular scars adhering to our DNA. Jews whose great-grandparents were chased from their Russian shtetls; Chinese whose grandparents lived through the ravages of the Cultural Revolution; young immigrants from Africa whose parents survived massacres; adults of every ethnicity who grew up with alcoholic or abusive parents — all carry with them more than just memories.

If your grandmother was adopted by nurturing parents, you might be enjoying the boost she received thanks to their love and support. The mechanisms of behavioral epigenetics underlie not only deficits and weaknesses but strengths and resiliencies, too. And for those unlucky enough to descend from miserable or withholding grandparents, emerging drug treatments could reset not just mood, but the epigenetic changes themselves.

DNA is the master code, residing inside the nucleus of every cell; RNA transcribes the code to build whatever proteins the cell needs. Then some of Razin’s colleagues showed that methyl groups could attach to cytosine, one of the chemical bases in DNA and RNA.

These attachments weren’t just brief, meaningless affairs. The methyl groups could become married permanently to the DNA, getting replicated right along with it through a hundred generations.

Without a mutation to the DNA code itself, the attached methyl groups cause long-term, heritable change in gene function. Other molecules, called acetyl groups, were found to play the opposite role, unwinding DNA around the histone spool, and so making it easier for RNA to transcribe a given gene.


Fuente: http://discovermagazine.com/2013/may/13 ... your-genes
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 06 Ene 2014 12:45

Si naciste en una familia acomodada o no, puede influenciar tu vida por los cambios epigeneticos:

Analyzed the methylation state of about 20,000 genes. Of these, 6,176 genes varied significantly based on poverty or wealth. Most striking, however, was the finding that genes were more than twice as likely to show methylation changes based on family income during early childhood versus economic status as adults.

Timing, in other words, matters. Your parents winning the lottery or going bankrupt when you’re 2 years old will likely affect the epigenome of your brain, and your resulting emotional tendencies, far more strongly than whatever fortune finds you in middle age.

Last year Researchers from Yale University published another study of human blood samples, comparing 14 children raised in Russian orphanages with 14 other Russian children raised by their biological parents. They found far more methylation in the orphans’ genes, including many that play an important role in neural communication and brain development and function.

“Our study shows that the early stress of separation from a biological parent impacts long-term programming of genome function; this might explain why adopted children may be particularly vulnerable to harsh parenting in terms of their physical and mental health,” said Szyf’s co-author, psychologist Elena Grigorenko of the Child Study Center at Yale. “Parenting adopted children might require much more nurturing care to reverse these changes in genome regulation.”
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 06 Ene 2014 12:50

Como cambiar tus caracteristicas epigeneticas: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3092901/

Recently, natural compounds, such as curcumin, epigallocatechin gallate (EGCG), and resveratrol, have been shown to alter epigenetic mechanisms, which may lead to increased sensitivity of cancer cells to conventional agents and thus inhibition of tumor growth.


Otro articulo sobre el tema: http://epigenie.com/take-a-bite-out-of- ... tics-diet/

- Tea polyphenols: The catechin EGCG, abundant in green tea beverages, inhibits the DNA methyltransferase DNMT1 and histone acetyltransferases (HATs)
- Cruciferous vegetables: Sulforaphane from veggies such as broccoli, cabbage, and kale inhibits DNMTs and histone deacetylases (HDACs).
- Fava beans, soybeans, kudzu: The isoflavone genistein inhibits DNMTs and HDACs and activates HATs.
- Turmeric: Curcurmin, a yellow pigment in the spice turmeric, inhibits DNMTs, HDACs, and HATs.
- Grapes, berries, peanuts: Resveratrol, a polyphenol made famous for its apparent anti-aging effects in animal models, inhibits DNMTs and activates the HDAC SIRT1.


Te verde (epigallocatechin gallate): alimentos-saludables-f112/verde-t1215.html
Curcuma: alimentos-saludables-f112/turmeric-curcumin-t1489-10.html
Resveratrol: suplementos-vitaminas-f114/resveratrol-t1514.html
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 07 Ene 2014 08:25

Cuidado demasiada metilacion es tan mala como demasiada poca, por lo tanto los extremos no son buenos, ahora bien donde esta el equilibrio?

Inducing DNA hypomethylation may have short-term anticancer effects, but might also help speed tumor progression from cancer cells surviving the DNA demethylation chemotherapy.


Fuente: http://europepmc.org/abstract/MED/12154403/

Cytosine hydroxymethylation was recently discovered as another important epigenetic modification on DNA in mammalian cells. Similar to methylation, hydroxymethylation replaces, at the C5-position in cytosine, the hydrogen atom by a hydroxymethyl group. It has been demonstrated that cytosine hydroxymethylation is also involved in gene regulation. For example, the hydroxymethylation level has been found to be associated with pluripotency of stem cells. Disturbed hydroxymethylation of DNA cytosine can result in disordered cell functions, causing different types of cancers.


Fuente: http://www.ks.uiuc.edu/Research/methylation/

Most tissue-specific genes are methylated. The methyl groups may generate a local chromatin configuration that renders the genes inaccessible, and thus transcriptionally inactive. This would provide a general mechanism for transcriptional repression which may operate independent of the requirement for interactions between cis-acting regulatory elements and tissue-specific factors. In contrast, house-keeping genes may not be affected by this inhibitory mechanism, and are thus available for constitutive expression in all cell types. Activation of tissue-specific genes from their generalized state of repression must first involve recognition of the genes while they are still methylated and this event initiates the process of transcription and concomitant demethylation. In their demethylated state these genes would be stably maintained in an active structure that is generally accessible to the transcriptional machinery of the cell.


Fuente: http://www.ncbi.nlm.nih.gov/pubmed/3280142
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 07 Ene 2014 12:26

The two main epigenetic mechanisms are shown below. These are termed DNA methylation and histone modification, and both determine whether the underlying DNA code can be read or not, and thus whether the DNA is able to make RNA. In particular, the methylation of target genes is usually associated with a dramatic reduction in their level of expression.
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 08 Ene 2014 20:26

Beneficios epigeneticos del Sulforaphane:

Sulforaphane was identified years ago as one of the most critical compounds that provide much of the health benefits in cruciferous vegetables, and scientists also knew that a mechanism involved was histone deacetylases, or HDACs. This family of enzymes can interfere with the normal function of genes that suppress tumors.
HDAC inhibitors, such as sulforaphane, can help restore proper balance and prevent the development of cancer. This is one of the most promising areas of much cancer research. But the new OSU studies have found a second epigenetic mechanism, DNA methylation, which plays a similar role.
"It appears that DNA methylation and HDAC inhibition, both of which can be influenced by sulforaphane, work in concert with each other to maintain proper cell function,"


El Sulforaphane se encuentra principalmente en los vegetales criciferos, y en cantidades 50 veces superiores en los tallos de Brocoli, el Sulforaphane parece ser un buen aliado contra la Helicobacter Pilory (www.buscandolalibertad.com/intolerancia ... t1223.html)
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 16 Mar 2014 05:35

There are more than 900 genes that Vitamin D is now known to switch on and off - and in doing so alters our vulnerability to disease. The large number of genes involved explains how so many quite different diseases can be caused by insufficient sunshine. In this way sunshine exposure directly alters the action of genes which may actually be passed on in their altered state – a newly understood process known as epigenetics. So it is possible to see how some diseases may emerge for the first time in one generation and be passed on to the next.
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 12 Jun 2014 20:43

It seems like all news lately is focused on the terrors of the world and transgenerational epigenetic inheritance has been no exception, usually with a strong focus on how an exposure or trauma finds a way to haunt generations. But now now an optimistic team from UCLA have shown that a lot can be learned from examining how DNA methylation is transmitted across generations in a ‘wild-type’ fashion.

In order to determine just how DNA methylation differs across one generation, the team examined the classical lab mouse strains (C57BL/6J and DBA/2J) and their F1 crosses using RRBS bisulfite sequencing. Here’s what they found:

There are a lot of reproducible methylation differences between the CpGs of the two strains.
These differences are also heritable between the parents and their F1 cross progeny.
There are about 400 genes with sex differences in methylation and 11% of them show differential expression across sexes.

As an added bonus, the team unveiled a fancy technique to detect allelically methylated regions (AMRs). The benefit of this one is that it is not limited to the use of SNPs to distinguish parent of origin. This approach identified 112 novel imprinted genes and miRNAs and the group went on to validate genomic imprinting at the RNA level in 10 of the genes. The authors conclude that the majority of DNA methylation differences across strains are related to genetic differences, with only a small amount be due to gender, genomic imprinting, or other stochastic transgenerational effects. However, they also point that these differences can be determining factor for heritability given the observed functional consequences and should be considered in all association studies for molecular and clinical traits
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Dalamar » 20 Ago 2014 17:59

Un video muy interesante!

http://youtu.be/xNA0DzGtTmU

Consumir brocoli, granada y te verde!
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Re: Freud contra Darwin! Epigenetica!

Mensajepor Kaizen » 20 Ago 2014 22:39

La verdad es que son excelentes los documentales de la noche temática, o por lo menos de lo poco que puedes ver y aprender en la TV! Me queda pendiente para ver! Has visto el de sobredosis de azúcar? https://www.youtube.com/watch?v=v0YQo5ky5cU

Cuando lo vea comento!


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