50

The phenomenon you're talking about was a fad in the 60's, called 'interanimal memory transfer'. It started out when James McConnell performed a later-discredited experiment in which he found that if you chopped up flatworms which had been exposed to some stresses, and fed them to other unexposed flatworms, the unexposed worms became wary of the source of ...


17

The assertion "You cannot change in life what will be genetically inherited in any possible way" is true, as you cannot (healthily) change the DNA in your germ cells. However, the assertion "You cannot change in life what will be inherited in any possible way" is wrong, because of epigenetics. Parts of your DNA are marked (in different ways), and this can ...


16

In general, Darwin's theory has been supported over and over again by experiments - our modern understanding of evolution is fundamentally what Darwin suggested. However, apart from appreciating many more details than Darwin ever could have, we also now know that Lamarck may not have been so crazy as he was later portrayed. Inheritance in the Darwinian ...


11

Well, don't use M or B, those are already taken (C or A, and not A, respectively). You can see the full list here: http://www.dna.affrc.go.jp/misc/MPsrch/InfoIUPAC.html (The enWiki article on Nucleobases lists a few others but I would ignore those as 1. D is present in both and 2. they are rare and inapplicable) 5-methylcytosine isn't on there. If you ...


10

I don't believe anything should change in the majority of DNA->RNA transcription. DNA methylation typically occurs on the non-watson crick side of Cytosine so it shouldn't affect the base-pairing. However, there are a few hypothetical situations that would result in alterations of the transcribed RNA. The sponatneous deamination of the 4' amine would ...


8

According to Choi et al. Genome Biology 2009, 10:R89, DNA methylation at both coding boundaries may regulate transcription elongation and stabilize splicing by reducing the occurrences of exon skipping. From the abstract: Here we report a genome-wide observation of distinct peaks of nucleosomes and methylation at both ends of a protein coding unit. ...


8

It is proposed that prions are a good mechanism for "testing" phenotypic variation. There are many identified proteins with prion-determining domains (PrD) in the yeast genome that can spontaneously switch between conformations with some low probability (eg: check SUP35 for one example, and [1] for a good overview of more). The theory is that: the low ...


7

This is somewhat unrelated, and for that, I apologize, but I find it truly fascinating, and I believe you will too. Zebra finches are a song bird that have become a popular model organism for behavioral research. They have a very stereotypical pattern for song learning: at about 70 days after hatching, the baby male song bird starts to listen to his father'...


7

The genome is the complete set of DNA in an organism, including genes and non-gene sequences of base pairs (bp).1 Each codon of three base pairs in a DNA sequence specifies one of twenty different amino acids. There are four available bases in DNA; Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). Four letters taken three at a time (where order ...


6

Jon Wilkins has a nice introduction to imprinting. He does a nice job of introducing the idea methylation and how these patterns are maintained during development and cell division. Further, he links to some interesting papers on the subject.


5

Absolutely. It's a pretty cool process, actually. Most (well...) DNA methylation occurs in the context of what are called CpG; that is, a C (Cytosine) followed by a G (Guanine). Because C and G are the Watson-Crick pair for each other, the sequence on the opposite strand will also be CG. Usually, both Cs are methylated, which turns out to be rather ...


5

Is the assertion "You can not change in life what will be genetically inherited in any possible way" true? No. Does not seems the case, as other people already replied. Here, I just want to point to two recent research articles showing evidence against your assertion. The first, published in Cell in 2010, is from Dr Oliver Rando, and suggests that you ...


4

Infections by a retro-virus (such as HIV) can, at least in principle, be inherited. These viruses integrate their genome into the host's DNA, and these changes pass to next generations as the cells split. So if a germ cell is infected, all the cells in the child would be. The question is whether there's a retro-virus that infects germ cells. I don't think ...


4

"Are these modifications the primary regulation mechanism for chromatin structure?" It depends on how you define primary, we might currently think of histone modifications as primary because other regulatory mechanisms have not yet been well studied. Something else you can think of are the various regulatory proteins that interact with histone marks to ...


4

In most tissues, close to 100% of DNA methylation occurs at CpG sites. This provides a straightforward mechanism for epigenetic inheritance. Since C and G are complementary, both strands have the CpG site at the same locus and methylation is either present on both strands or on neither. During replication, each daughter DNA molecule inherits a parent strand ...


4

Vision deteriorates for both reasons, but I'm not quite sure how to separate the effects of aging from wear and tear. Cataracts are the leading cause of blindness in the world. Ways in which environment (which falls under the category of wear and tear in my book) affects cataract formation: UV light: people living at high altitudes (e.g. Tibet) have more ...


4

Dyad is the centre of the DNA that is wrapped around the nucleosome core (It basically is the centre of symmetry of the nucleosome). It is a common practice to set it at 0 thereby making incoming DNA half, negative and outgoing DNA half, positive. By oscillations the authors mean that there is a periodic repeat of A/T dinucleotide. IMO it is actually not ...


4

There are definitely genomic DNA sequences that nucleosomes preferentially package in vitro. They are A/T rich and have a periodic structure that facilitates bending. However such sequences would typically not be found on exons in vivo (because their protein-coding potential is reduced). Based on the accumulating literature, active promoters (and regions ...


4

Spermatogenesis (Beginning to end): 64 +- 8 days (range 42 to 76) There is considerable individual variation. This includes time in epididymis. Amann 2008 argue for 74 days based on early study by Clermont 1972. Also argue that biopsies are still needed on top of radiolabelling. Substages: Calculated from Amann 2008, Figure 1 using percent time in 16 ...


4

Epigenetic marks are reversible (you might be aware of induced pluripotent cells). Many animals can regenerate organs with high tissue complexity (such as a limb) and this involves de-differentiation in some species (Sandoval-Guzman et al., 2014). Even otherwise, cells can respond to extracellular/environmental cues to modify their epigenetic state (for e.g. ...


4

First, let me qualify the idea of "problematic" epigenetic modifications by saying that the impact of a modification on an organism is often dependent on the environment. That is to say that outcome is dependent on the interaction of genetics (or epigenetics) and the environment in which the associated genes are expressed; e.g. a mutation or modification ...


4

A methylated nucleotide is the same nucleotide, for the purposes of base-pairing events. The methylated base will be paired with its Watson-Crick opposite after replication, for instance (and methylation will even persist after replication).


3

The hairs you mention are also called "androgenic hairs", meaning their growth and pigmentation is influenced by androgens. These include pubic hair, the hairs on the breast and shoulders (almost exclusively for men) and the beard. It seems, that these hair bulbs have different sensibilities (number and expression of androgen receptors) so they react ...


3

I would think there have to be, though do you mean collecting samples on a regular basis and plotting out the difference at each point? Or do you simply mean the total accumulated change. If it is the latter, the answer is certainly "yes". You have probably seen the Nova documentary "Ghost in Your Genes" (The US, not BBC one). In it they show comparison of ...


3

Depending on the exact goal of the experiment, the researchers may back-cross both to smooth out genetic variation between individuals and to potentially normalize expression of a transgene, although once you get past the chimeric stage gene expression should be fairly stable. In my experience, back-crossing allows you to generate a genetically-altered mouse ...


3

Within that region, there are multiple genes. Although the same gene may control imprinting for both disorders, the gene(s) causing their phenotypes differ. AS results from underexpression of a single gene, UBE3A, which codes for E6-AP, a protein that functions to transfer small ubiquitin molecules to certain target proteins, to enable their ...


3

In tree growth there is principle called The axiom of universal stress whereby the growth is in such a way as to equalise the stress across the whole of its structure. The roots, the stem and the branches are one continuous system and can not be thought of as separate. On a simplistic level for a branch to grow, there must be a corresponding equal and ...


3

No. Epigenetic information is (by definition) NOT included in the nucleotide sequence, but affects genetic expression. Enhancers/silencers are themselves nucleotide sequences, and therefore not epigenetic information. Methylation is an example of epigenetic information, but a DNA sequence itself is genetic information, even if it affects a gene. ...


3

CG methylation has long been associated with gene silencing due to the generally negative correlation between gene promoter methylation and transcription levels. When CG methylation occurs in the promoter or enhancer region of animals (where these 'CpG islands' tend to be), methylation seems to impede (to some extent) transcription factor (TF) binding. ...


3

Dominance is defined based on the phenotype Dominance is defined based on a phenotype of interest. Pick a phenotype, say coat color for example. If genotypes AA and Aa have the same coat color while aa has another coat color, then A is domiant over a. The concept hold even for sequence that do not produce proteins The concept of dominance can be applied ...


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