Talk:Telomere/Archive 1

Archive 1

Telomere Shortening Section

The “Telomere Shortening” section says that only the lagging strand becomes shortened. This is FALSE. The RNA primer on the 5’ end of both the leading and lagging strands cannot be replaced and are dropped. The authors’ confusion likely came from reading a text that said leading strand replication proceeds without any issues. This simply refers to replication being able to proceed uninterrupted. It is not a reference to the telomeres. For DNA polymerase III to bind at the 5’ end of DNA, an RNA primer must be in place. This is true for both the leading and lagging strand. The RNA primers within the lagging strand are removed by DNA polymerase I but the primers at the 5’ end (either 5’ end) are not removed. They are eventually enzymaticly degraded and thus result in telomere shortening on BOTH strands. Additionally, this section has no citations and I don’t have the time to rewrite it. Can someone please take care of this? —Preceding unsigned comment added by Scootdive (talk • contribs) 23:39, 7 October 2009 (UTC)

Since the leading strand starts at an origin of replication in the middle of a chromosome, there should be no problem replacing the RNA primer of the leading strand with DNA. The first RNA primer synthesized to begin the lagging strand will eventually provide the necessary 3’ end for DNA ligase I to work and connect the lagging strand to leading strand. Also, the leading strand will continue elongating in the 3’ direction until it reaches the 5’ end of the template DNA. I think you might be confusing the terminology of parent (template) vs. daughter strands, and lagging vs. leading (the two daughter) strands. There are two lagging strands and two leading strands per replication bubble. One of each combine to form one new daughter strand. Only the 5’ end of each daughter strand (the lagging strand end) will have the shortening problem. You are correct that there are two sites for telomerase action per DNA molecule, one on each 3’ end of template DNA. However, this telomere lengthening allows the lagging strands on either end to lengthen.

Also, DNA polymerase III and DNA polymerase I are prokaryotic polymerases, which would not be involved in eukaryotic replication. Only eukaryotes have telomeres and telomerases since their DNA is not circular. Cmcnicoll (talk) 01:03, 30 October 2009 (UTC)

Use of the term "Assay"

I changed the heading "Telomere Length Assay" to "Measurement of Telomere Length in the Laboratory", because it is my experience that the lay public is not familiar with the term "assay." —Preceding unsigned comment added by 208.59.168.214 (talk) 23:43, 29 April 2009 (UTC)

Telomere attrition by magnesium deficiency

Someone more skilled in editing Wiki articles than I needs to add the recent observation by David Killilea and Bruce Ames that magnesium deficiency (long known to accelerate aging) causes telomere attrition. Their abstract reads:

"Magnesium inadequacy affects more than half of the U.S. population and is associated with increased risk for many age-related diseases, yet the underlying mechanisms are unknown. Altered cellular physiology has been demonstrated after acute exposure to severe magnesium deficiency, but few reports have addressed the consequences of long-term exposure to moderate magnesium deficiency in human cells. Therefore, IMR-90 human fibroblasts were continuously cultured in magnesium-deficient conditions to determine the long-term effects on the cells. These fibroblasts did not demonstrate differences in cellular viability or plating efficiency but did exhibit a decreased replicative lifespan in populations cultured in magnesium-deficient compared with standard media conditions, both at ambient (20% O2) and physiological (5% O2) oxygen tension. The growth rates for immortalized IMR-90 fibroblasts were not affected under the same conditions. IMR-90 fibroblast populations cultured in magnesium-deficient conditions had increased senescence-associated β-galactosidase activity and increased p16INK4a and p21WAF1 protein expression compared with cultures from standard media conditions. Telomere attrition was also accelerated in cell populations from magnesium-deficient cultures. Thus, the long-term consequence of inadequate magnesium availability in human fibroblast cultures was accelerated cellular senescence, which may be a mechanism through which chronic magnesium inadequacy could promote or exacerbate age-related disease."

This article is in the Proceedings of the National Academy of Sciences, (PNAS April 15, 2008 vol. 105 no. 15 5768-5773.) which is online at: http://www.pnas.org/content/105/15/5768.abstract —Preceding unsigned comment added by Georgeeby (talk • contribs) 03:42, 11 July 2008 (UTC)

Telomeric interval?

What is a telomeric interval? Tmangray 23:46, 11 April 2007 (UTC)

Correct me if I'm wrong but I believe the term 'telomeric interval' refers to sections within a telomere. ShanSabri (talk) 18:54, 2 October 2012 (UTC)

5 to 3

what does "5' to 3'" mean?

It's how one describes the "direction" of a sequence of DNA bases. The 5 and 3 refer to specific atoms that are part of the deoxyribose sugar ring in the DNA's backbone; the phosphate links between two deoxyriboses connects the 5' carbon of one deoxyribose to the 3' carbon of the next one. I'd need to draw a diagram to explain it really clearly, but this is something that should be handled within the DNA article. Bryan Derksen

Here is a schematic:

3'-------------------------5'
<enzyme> -->
5'-------------------------3'

The enzyme works here from the 3' to the 5' end (each - represents a base pair). It moves along the 3'-5' direction polymerizing in the 5'-3' direction. All the polymerases that have been discovered polymerize in the 5'-3' direction. This is a very important point to remember if you want to develop a deeper knowledge of biology and the process of DNA replication (and RNA synthesis, because it follows the same rule except that the RNA transcript is made in the 5'-3' direction). Ashermadan

I already put the explanation in DNA. Did I get the direction right? phma

I remember reading speculations that telomere could cause problems with cloning since the DNA used would have already shorter telomere. I'm loathe to add that without having any source to cite, though.

---

Regarding telomere shortening as a time-delay fuse, the article currently states "These theories remain relatively controversial at this time.". Is that true? Could a reference be added to a paper arguing otherwise, or is it simply that the theory is very new and relatively untested? I'd love to here more detail about why it is controversial, others probably would too. Bmord 07:03, 7 January 2006 (UTC)

---

The article states that for most multicellular eukaryotes, telomerase is only active in germ cells. However, the reserve capacity hypothesis article linked in the references section asserts that some amount of telomerase exists in adult skin cells. Also, prior to 5 months of age, somatic cells in zygotes apparently also express telomerase. Could this be rephrased to something more correct? Thanks. Bmord 07:03, 7 January 2006 (UTC)

Heat Resistance +

"A side effect of the longer telomeres was an increased resistance to the effects of heat exposure. The reasons for that effect are unclear."

With the increase in global warming is this not an experimental aspect to explore on humans in Africa who die every day of heat related symptoms, as well as children left unattended during the summer that either die or experience life crippling afflictions? Depending on the true uses of such a new treatment, it would certainly be worth it to explore every possibility such a treatment would bring forth, would it not?

Reformatted --Chris 00:40, 8 July 2006 (UTC)

Misspelling on telomere page

The species Candida guilliermondii is spelled wrong, as guillermondii. This is especially a problem because elsewhere in Wikipedia Candida guilliermondii is classified under Pichia guilliermondii, which is an old usage, I believe. Makes it hard to look stuff up. It's not anywhere in the text, it's in the table of sequences. Richard8081 05:36, 17 July 2007 (UTC)

RNA in telomeres!

Here's a fascinating article: New Telomere Discovery Could Help Explain Why Cancer Cells Never Stop Dividing. Someone should really read the original article and include some of that information here. Unfortunately, I'm a bit swamped at work. --Slashme 08:11, 8 October 2007 (UTC)

Running Out?

How many years can the telomers shorten until their completly gone? —Preceding unsigned comment added by 70.100.23.242 (talk) 00:21, 19 January 2008 (UTC)

That depends on how quickly the cell is dividing. I don't know enough about the speed of division of cells to give you an accurate answer though I think you will find it will vary widely. Skin cells, for example die and are replenished very quickly, whilst other cells such as neurone stem cells divide rarely (at least in adulthood).

131.111.1.66 (talk) 23:32, 7 November 2009 (UTC)

Tips of shoelaces

I first saw the metaphor of telomers as being like the tips of shoelaces in Science News.

Metaphors are common and useful in explaining science, in classes, magazines and textbooks.

I think the metaphor makes the function of telomeres easier to understand. I'm not sure what it takes away from the article -- perhaps people want the article to be serious and it's too mundane.

Can you tell me, SierraSciSPA, why you don't think it belongs in the article? I'm not insisting that it go in, but I just want to articulate a good reason, for the record. Nbauman (talk) 03:06, 30 January 2008 (UTC)

Well, for the record, I think the metaphor of telomeres to aglets is very questionable. Aglets have two main purposes: 1) to protect laces from fraying; and 2) to make laces easier to fit into holes. Telomeres have several known purposes, including: 1) to protect the ends of chromosomes; 2) to provide a disposable buffer for DNA polymerase, which cannot replicate a complete sequence of DNA; 3) arguably, to ensure that deletorious mutations will be only as long-lived as the Hayflick Limit and thus to reduce the incidence of cancer. Bottom line: while aglets and telomeres do certainly have one thing in common, it seems that the differences between them are far more significant than the similarities. I think drawing the comparison is more likely to mislead than to inform. I'm certainly not going to edit war over this point, but that's pretty much what I think of it.

That said, though, in general, I applaud your efforts to make this article more readable to a layperson. I myself *am* a layperson, and when I read it for the first time, I was completely bewildered. The article includes the sentence "during replication, DNA polymerase can only synthesize DNA in a 5' to 3' direction and can only do so by adding polynucleotides to an RNA primer that has already been placed at various points along the length of the DNA." How is any non-biologist supposed to be able to read that?? --SierraSciSPA (talk) 05:42, 30 January 2008 (UTC)

You're saying that we shouldn't use the metaphor that telomeres are like the tips of shoelaces, because telomeres share only one quality with shoelaces, but have many other qualities that they don't share with shoelaces.

I don't quite follow that. Science writers and teachers often use metaphors to get their ideas across, and the comparison usually shares only one point of description. For example, people compare the DNA molecule to a ladder, but a ladder has all kinds of qualities that DNA doesn't have. You can climb on a ladder, but you can't climb on a DNA molecule. Ladders are made of wood or metal, but DNA molecules are not. People compare the DNA molecule to a blueprint, but there are lots of differences between a literal blueprint and DNA.

Scientists use metaphors all the time, to explain and even to develop their ideas. They describe molecules as "gatekeepers". They compare a part of the brain to a sea horse, or a telephone exchange. Günter Blobel famously described his address tags to Zip codes. The Nobel Prize speeches are full of such metaphors.

Metaphors are a basic part of thinking. You can't be too literal and reject them. As you may know, one the symptoms of severe mental illness, such as Alzhemier's disease, is an inability to understand metaphors[1]. I'm not suggesting this is a problem here.<g> Nbauman (talk) 14:53, 30 January 2008 (UTC)

I'm not going to take a stance against all metaphors - but the two things being compared in a metaphor should at least share a primary purpose. DNA and a blueprint both contain instructions for structures; mitochondria and power plants both generate energy that will be used elsewhere. But the primary purpose of aglets is to protect the ends of something, and with telomeres I think that's only a secondary purpose - the primary purpose of telomeres is to enable the DNA polymerase to do its job, thus making replication possible. I almost want to argue that a telomere is more like copy machine toner than an aglet - that is, you need it to make copies, and it eventually runs out. Note, however, that I really don't want to say "telomeres are like copy machine toner" in the article :) --SierraSciSPA (talk) 16:37, 30 January 2008 (UTC)

Relative brightness

Is the grey of the chromosomes and the bright white of the telomeres in the photo the result of emitted light, or stimulated (how?) emission, or variations in reflectance / transmission? bucksylBucksyl (talk) 17:22, 18 February 2008 (UTC)

I would presume the telomeres had been labelled with a fluorescent dye (possibly by attaching it to a telomere specific antibody) Hence when light of the correct wavelength hits the chromosomes the dye is excited and emit light of a different wavelength and the light is observed. This probably uses confocal microscopy-look it up if you want to know more.

For the record, the reason the chromosomes show up in gray is probably because the antibody is specific to a certain (repeating) sequence that is present in telomeres, but the sequence occasionally occurs in the DNA of the chromosome, hence resulting in a low level of illumination of the rest of the chromosome where the sequence is present.131.111.1.66 (talk) 23:44, 7 November 2009 (UTC)

While I can't be certain, what you are seeing in that image is almost certainly an image of fluorescent in situ hybridization (FISH) for telomeres. Cells are isolated while dividing and prepared such that the chromosomes remain intact. The solution containing chromosomes is then literally dropped onto glass slides (called a "metaphase spread"). In this case, the chromosomes are then hybridized with a fluorescently-labeled DNA or PNA probe that has a complementary sequence to the telomere. The chromosomes are stained with a DNA dye such as DAPI or Hoechst that fluoresces when bound to DNA (with different excitation and emission maxima than the fluorophore used to label the telomere probe). After all the processing, the chromosomes can be photographed using standard epifluorescence / wide-field microscopy (confocal is rarely used for metaphases since there is very little sample depth and an infrequent need for absolute colocalization of multiple signals). Each channel (the DNA dye, and the telomere probe) is stimulated and the fluorescence captured separately, and these can be merged into a multicolor image. What the picture here shows is simply a grayscale version of this multicolor image where the telomere signal, as it often is in metaphase FISH, is considerably brighter than the DNA dye. Sorry to throw all that out, but I figured I'd clarify - while immunofluorescence (detection with an antibody) can be used to find telomeres in metaphase spreads, it is uncommon because FISH is technically much simpler to perform. Dcteas17 (talk) 08:44, 9 November 2009 (UTC)

Wow.

Doesn't biology just blow your mind? —Preceding unsigned comment added by 79.68.146.250 (talk) 23:50, 3 March 2008 (UTC)

Only now and then. SteveD 10:59 am 30th May 2008. —Preceding unsigned comment added by 124.180.135.136 (talk) 01:00, 30 May 2008 (UTC)131.111.1.66

Immortal butterfly

What you'll get if you will connect the ends of the X's? Eternity ;) Denis Tarasov (talk) 09:03, 2 June 2008 (UTC)

Telomere Shortening

During repeated cell division, do the telomeres of its chromosome shorten by a certain number of 6-nucleotide repeats (in the case of humans)? Is it predictable or random during each division? Will the chromosome not necessarily lose 6-nucleotide repeats, and lose say one and a half repeats? Adee08 (talk) 17:41, 28 July 2008 (UTC)

Ambiguity

Re: forensics, you can "determine the age of any forensic sample that contains well-preserved DNA." I find the sentence a bit ambiguous—what it really means is you could, for example, tell how old someone was from their DNA, right? It wouldn't tell you the age of the cell itself (it would tell you how many repetitions that cell represented from the initial birth of the organism), it wouldn't tell you the age of the sample (the sample could have died 20 years ago, the telomere length would not have changed), etc. It has a pretty specific "age" meaning here. I'm having trouble articulating a clearer version of this, but perhaps someone can do that. If I had a DNA sample of a 5 year old girl taken 20 years ago, the telomeres would tell me the sample was 5 years old, not 25 years old. If said girl was still alive, the sample would only be telling me how old the girl was when the sample was taken, not how old she is now. The sample itself was not 5 years old when it was taken—it just represents a cell which is five-years-removed from the birth of the organism. Right? --98.217.8.46 (talk) 22:24, 13 August 2008 (UTC)

References

It seems to me that there are at least some references in this article that aren't written in the usual "wikipedia manner" that most are, I'm thinking of mainly the first part of the "Human telomeres, cancer, and ALT." section, the references are written in brackets after the sentence, instead of with a link? I'm not sure if this is the way it's supposed to be after all, and I have no idea how to make them look right...so I figured someone experienced could do something about it, if it's possible.

Hannes, 83.255.65.145 (talk) 23:47, 6 March 2009 (UTC)

Biologists speculate a tradeoff between aging and cancer?

I think the line "Biologists speculate that this programmed death of potentially damaged cells reduces the likelihood of cancer but makes aging (and thus death) inevitable."

is too broad a generalization, and also, is not referenced. The article even later states that it is not even certain that telomeres cause aging:

"First, it is not even certain whether the relationship between telomeres and aging is causal. "

Also, programmed cell death (apoptosis) is not the same as cell "aging" or senescence.

For now I am going to remove the line as the issue of the cancer/aging trade off is better discussed later in the article.

Masparasol (talk) 23:53, 21 April 2009 (UTC)

What a shame!

Where is Nobel prize for Alexei Olovnikov? What a shame! —Preceding unsigned comment added by Vbg1975 (talk • contribs) 21:12, 5 October 2009 (UTC)

New research shows potential link with Omega 3

Should this be integrated?

" ... New research suggests the fatty acids may possess an even more fundamental benefit: Heart patients with high omega-3 intake had relatively longer "telomeres," which are stretches of DNA whose length correlates with longevity. ... "

http://online.wsj.com/article/SB10001424052748703837004575013393566949312.html

Cowicide (talk) 01:10, 20 January 2010 (UTC)

I'd say no -- probably better to wait for a few studies to replicate since there are so many studies in this field right now. —Preceding unsigned comment added by Pengortm (talk • contribs) 12:49, 17 May 2011 (UTC)

Poor grammar limits understandability

There is some poor grammar, especially in the intro section. Also, results from this study: http://www.scientificamerican.com/article.cfm?id=aging-telomere should be incorporated.

Climbbum (talk) 03:12, 14 February 2010 (UTC)

Telomerase Activators, Telomerase Inhibitors, and Telomere Therapy

For a discussion of telomerase activators (7) and telomerase inhibitors and firms selling therapy for telomeres, see http://greenwdks.hostse.com/longevity.html or the backup site http://greenwood.s5.com/longevity.html. This site also includes a general review of life extension medicine with extensive references and links to books, clubs, blogs, and on-line journals in the field. —Preceding unsigned comment added by JamesAGreen (talk • contribs) 22:51, 15 July 2010 (UTC)

Please note self promotion of this sort is highly frowned upon 162.111.235.34 (talk) 19:36, 30 March 2011 (UTC)

Overall style of this article - too many researchers shilling their own pet work?

Much of this article seems to be self-promotion of particular researchers relatively small and non-representative studies. While it is great for active scholars to contribute to this article and fine for them to cite their own work, this should be done in such a way which highlights the findings and their implications for a larger and more general understanding. As is, more time is often spent on mundane research details and the author affiliations than cleanly integrating the work into the article. —Preceding unsigned comment added by165.124.163.251 (talk) 16:29, 31 December 2010 (UTC)

Pronunciation guide

Would someone add a pronunciation guide to this article, if there is an agreed pronunciation? A quick Google search has not yielded an answer for my pronunciation query. Is it "TEE-lo-meer" or "TELL-lo-meer"? Many thanks. Careful With That Axe, Eugene ^Hello... 09:59, 17 May 2011 (UTC) There might not be a consensus pronunciation, although I think a good guide might be had by listening to the recent Nobel prize lectures (videos are online) to see how those three authorities pronounce it. —Preceding unsigned comment added by Pengortm (talk • contribs) 12:48, 17 May 2011 (UTC)

Added overview

I have added a "Background" section aimed at making the article more understandable to non-experts. David F (talk) 01:32, 14 July 2011 (UTC)

I removed the "Background" section since it repeated general cell biology which is admirably covered in existing articles which can be accessed with a single click. I appreciate efforts to make the article more readable to the general reader, especially since someone has flagged it for such improvement, but repeating general principles is not a good way to wrestle with that issue. -R. S. Shaw (talk) 04:57, 15 July 2011 (UTC)

I am a professional technical writer with several years experience explaining technical subjects. I spent several hours adding the "Background" section in response to the comment suggesting the article should be more understandable to non-experts. I dispute the assertion that summarising general principles is not of value. I therefor undid the removal of the section, but followed the suggestion to remove references to items previously mentioned and linked to in the introduction. David F (talk) 03:58, 17 July 2011 (UTC)

Not to get in the middle of you guys, but the background section struck me as being out of place for this article when I first read it. Ironically, even the simple.wikipedia version does not have this section. That being said if the consensus is to keep it, I think it should at least be linked back around to the topic of telomeres itself. For instance, "... every cell has DNA... DNA is comprised of chromosomes.... and telomere are the ends of those chromosomes ... ." Side note - red blood cells do not contain DNA, so "every cell" should probably be rephrased too. Bobtheowl2 (talk) 04:23, 24 July 2011 (UTC)

neighboring chromosomes?

The first line says "from fusion with neighboring chromosomes".

Does this mean chromosome 1 and 2 are neighboring? are they always close to each other in the cell?

or does it mean chromosomes that are beside each other in the cell just by chance. — Preceding unsigned comment added by 130.238.155.40 (talk) 08:26, 1 October 2012 (UTC)

chromazones are like fuzzy catiapillars

The best that I can tell so far is that the chromazones are like fuzzy catiapillars who pick up all vibrations they are exposed to. If there are any new ones they are added to the chain and a copy of the addition is made. Now the telomeres are medical repaire. They for some reason are laid dormate and it is up to the individual to reactivate them. It is said if you smoke do not because the experience will be to intense for most people.I know from personal experience and I like rollacoster rides anyway.I sometimes spell words incorrectly so I will know your condition. Lately no one seems to care so I better learn how to spell. I am Steven Allen Bellmer... — Preceding unsigned comment added by 99.67.18.94 (talk) 09:07, 14 November 2013 (UTC)

Chromosome ends replication problem

The information given in the "Shortening" section is not ok. Citing: "On the leading strand, DNA polymerase can make a complementary DNA strand without any difficulty because it goes from 5' to 3'." In fact, there is one difficulty resulting in sequence shortening and it is the same one as in the case of the lagging strand. The replication of the leading strand to be initiated, there must be synthetized an RNA primer as well. One is sufficient at the beginning of the new strand. Eukaryotic DNA is usually replicated from several origins of replication (ori) as stated in the article, so the RNA primers occuring in the middle of the chromosome are further converted to DNA by RNase, DNA polymerase and DNA ligase. However, the situation is different while replicating the 3' of template DNA molecule. RNA primer synthetized at the end of the chromosome will be degraded, but won't be converted into DNA, because there is no room for new primer from which the replication could start. Thus, both new DNA strands (lagging as well as leading) will lack a short sequence at their ends.Marian Varga (talk) 15:21, 8 February 2014 (UTC)

Telomere shortening and Cancer risk

There is a lot of information describing the role of telomerase and limitless replicative potential in cancer cells (see the Telomerase article). However, telomere shortening has been associated with aging & aging-related diseases, such as cancer. It would be interesting to include this as a separate topic under the cancer section. Several studies indicate that shorter telomeres, particularly in immune cells, are a risk factor for cancer. Recent research has studied how lifestyle factors including diet, exercise & stress management can increase telomerase activity and telomere length (Ornish et al. 2013, Frattaroli et al. 2008). Also, the role of diet in cancer incidence & progression has been studied, particularly in prostate and colon cancer (Pellatt et al 2012, Mirabello 2009). A recent study found an association between dietary meat consumption and shortened colonocyte telomeres in rats (O’Callaghan et al. 2012). Telomere lengthening through lifestyle changes is an interesting topic of disease prevention research which could enhance this article. Whitneym89 (talk) 20:25, 9 February 2014 (UTC)

Needs restructuring and or splitting

Some duplication of content. Could split out some into telomeres and cancer ? - Rod57 (talk) 00:22, 4 August 2015 (UTC)

Section too technical?

There is a Wikipedia notification for the "Human telomeres, cancer and ALT (Alternative lengthening of telomeres)" section, saying it is too technical. I am in high school biology, and found this section of the article to be exactly what I am looking for. If you have even the slightest background in Biology (which you probably would when reading this article), or are willing to look up some of the other terms, you should be fine. Just like with anything else. This is not nearly as technical as it could be. I suggest removing this notification. 199.126.128.121 (talk) 05:31, 1 November 2012 (UTC)

I agree, and no one has objected so lets remove the notification. - Rod57 (talk) 00:12, 4 August 2015 (UTC)

I agree it is not too technical but it is poorly written. The first sentence begins; "Malignant cells that bypass this arrest become immortalized ......" But" ..this arrest.." is not preceded by any explanation of, or reference to, an "arrest": so now the reader is wondering what they missed. I went back through the article and if there is a previous reference to an "arrest" I couldn't find it. This is just plain bad writing. then the author resorts to cutesy quotes; "but DNA polymerase can only "backfill" deoxyribonucleotides if there is already DNA "upstream". More bad writing. Why are "backfill" and "upstream" in quotes?99.102.187.153 (talk) 12:34, 6 August 2015 (UTC)tim

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Missing: Hermann Muller and Barbara Mcclintock

Hermann Muller (who coined the term telomeres in 1938) and Barbara Mcclintock who noticed that ends of chromosomes play a protective role — Preceding unsigned comment added by ערן78 (talk • contribs) 05:46, 9 April 2016 (UTC)

Telomere sequence table is wrong for higher plants

Regarding higher plant telomere sequences, check out this reference:

Centromere and telomere sequence alterations reflect the rapid genome evolution within the carnivorous plant genus Genlisea Trung D. Tran1,†, Hieu X. Cao1,†, Gabriele Jovtchev1,‡, Pavel Neumann2, Petr Nov�ak2, Miloslava Fojtov�a3, Giang T.H. Vu1, Ji�r�ı Macas2, Ji�r�ı Fajkus3,4, Ingo Schubert1,3 and Joerg Fuchs1,*

"In vascular plants, the heptanucleotide repeat (TTTAGGG) which was first discovered in Arabidopsis thaliana (Richards and Ausubel, 1988) is the most common telomere sequence (Fuchs et al., 1995). Nevertheless, this plant-type telomere repeat is replaced completely or partially by other repeats such as (TTAGGG) or (TTGGGG) or by unknown sequences within families of the monocotyledonous order Asparagales(Adams et al., 2001; Weiss and Scherthan, 2002; Sykorova et al., 2003c, 2006). Telomere repeat alteration was also detected within species of the dicotyledonous family Solanaceae (Sykorova et al., 2003a; Peska et al., 2015)."

The Arabidopsis-type telomere repeat present in G. nigrocaulis were replaced by two variant sequences (TTCAGG) and (TTTCAGG) in G. hispidula and its close relative G. subglabra." — Preceding unsigned comment added by 206.190.72.205 (talk) 20:18, 28 July 2016 (UTC)

Revert

@Dan Eisenberg: reverted my edits, asking me not to post abstracts of my articles. I presume he thinks I wrote the source in question. Not me. I do not edit war, but I think the revert is unwarranted and would appreciate the thoughts of other editors. The paragraph in question is:

A 2016 phase 1–2 prospective study orally administered 800 mg per day to 27 patients with telomere diseases. The primary efficacy endpoint was a 20% reduction in the annual rate of telomere attrition measured. Toxic effects formed the primary safety endpoint. The study was halted early, after telomere attrition was reduced in all 12 patients who could be evaluated. 12 of 27 patients achieved the primary efficacy end point, 11 of whom increased telomere length at 24 months. Hematologic responses (secondary efficacy endpoint) occurred in 10 of 12 patients who could be evaluated at 24 months. Elevated liver-enzyme levels and muscle cramps (known adverse effects) of grade 2 or less occurred in 41% and 33% of the patients, respectively.

Lfstevens (talk) 22:20, 1 August 2016 (UTC)

Sorry for being harsh in the edit comment and assuming it was your article. Regardless, it is not encyclopedic to add this level of detail for one particular study which is not clearly that noteworthy. Dan Eisenberg (talk) 01:23, 2 August 2016 (UTC)

Reference fault

Reference to "COSMOS: The Science of Everything", currently #15, not found. 94.30.84.71 (talk) 19:07, 18 April 2017 (UTC)

Olovnikov

The section and sources below were removed because a) they advance only a theory that is part of telomere discovery, but developed more completely with actual evidence by others, b) they source references, some in Russian, that were superseded by more recent and complete sources, and c) the Olovnikov discussion - which is promotional to his theory and off-topic to current knowledge about telomeres - can be stated more simply, and is given coverage at Hayflick limit. In this revision, I trimmed the discussion and added a review. --Zefr (talk) 23:08, 13 March 2018 (UTC)

soviet/russian biochemist Alexei Olovnikov was first to formulate and published the theory of marginotomy (in The Journal of Theoretical Biology, 1973), concluded in that chromosomes could not completely replicate their ends. Building on contemporary state of the art and accommodating Leonard Hayflick's experimental results of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell/DNA replicates until the loss reaches a critical level (Olovnikov's clock), at which point cell division ends. Basing on the theory, he explained endless and non-aging division of bacterial cells by circular structure of their DNAs, and the same in stem and cancer cells by acting of unknown cap-recovering enzyme - discovered in 1984 telomerase. However, neither he nor his contemporaries (Watson, the end-replication problem, 1972) were not awarded the Nobel Prize for this discovery.

References

a) As for the theory, it's ability to explain the peculiarities of bacterial, spinal and cancer DNA, emphasized the correctness of the underlying assumptions and indicated the direction of further research. The mention of the essence of the theory is important for reflecting the development of the concept of telomeres and telomerase.

b) The underlined statement that the English-language publications of Olovnikov went unnoticed sounds strange, given the much smaller volume of scientific publications in 1970s, especially in cell biochemistry, and general accessibility of abstract journals. Apparently the author of the line was not very good at the question.

c) The discovery of telomeres by Blackburn, concerned in telomeres themselves, whereas Olovnikov's ideas were more general and universal, and in essence were an interpretation of already available experimental results, but not a bare hypothesis.

D) The first and very quick undo of the editing ("Was clear enough before.") emphasized the formal relation of the Editor to his work.

e) The removal of actual references to original articles under the pretext of "that were superseded by more recent and complete sources" deprives the paragraph of actual reinforcement, and the reader of access to the original source. Only 1 arcticle is in russian. — Preceding unsigned comment added by Vavilevskii (talk • contribs) 18:13, 14 March 2018 (UTC)

That's more history than Olovnikov deserves for theorizing about (not discovering) telomeres, as the Nobel prize and historical literature indicate. The content you added overpays Olovnikov's contribution, and the sources are neither the current understanding nor are they readable by the typical WP user. The current version reads:

"In the early 1970s, Russian theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends. Building on this, and to accommodate Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division ends." Sourced by PMID 27182535

This seems adequate acknowledgement of Olovnikov's role in the discovery. --Zefr (talk) 18:41, 14 March 2018 (UTC)

Telomeres and cancer section

There is an awful lot of information on Telomerase in the cancer and Telomerase section. I believe this should be moved to the Telomerase page, however I do not have much expertise on the subject and so open up a request for someone else to edit this?

Also, I plan to work on the ALT section. I don't know about moving this out into a separate article for the time being; there is not much information and I feel it fits well into the Telomere article after the re-jig.--Rachemon (talk) 18:03, 10 August 2016 (UTC)

Hi, sorry, I don't know how to comment on the actual section I have a question about. I updated a link in the External Links section that was out of date. (The link had changed on the linked-to site, iBiology.) Someone first reverted the link to the bad, old link, then removed it entirely. Liz's talk on the iBiology is an excellent video of her explanation of her work. I do not understand the series of edits that were made. Can someone revert to my original edit, which corrected a bad link? Yowangdu (talk) 22:39, 2 July 2018 (UTC)

The topic of telomeres is still in the research stage, i.e., it's WP:PRIMARY, which is too undeveloped to include much about it as encyclopedic other than as preliminary research. For medical topics, such as lowering cancer risk, we use the sourcing guide, WP:MEDRS, and this tutorial may help. Please don't stretch the telomere content beyond what can be supported by MEDRS sources. The Lengthening section needs work. --Zefr (talk) 23:45, 2 July 2018 (UTC)

Reverse Complement

The article states that "the sequence of nucleotides in telomeres is AGGGTT,[1] with the complementary DNA strand being TCCCAA", but the actual reverse complement of AGGGTT is AACCCT. The complementary DNA strand is traditionally written in the same reading direction as the standard DNA strand. — Preceding unsigned comment added by 118.92.191.30 (talk) 07:21, 22 September 2019 (UTC)

Proposed addition to existing section ‘7. Measurement’

Information to be added: Flow-FISH [2] is used to quantify the length of telomeres in human white blood cells. A semi-automated method for measuring the average length of telomeres with Flow FISH was published in Nature Protocols in 2006.

Explanation of issue: Additional available telomere measurement technique currently not mentioned, in the interests of providing an accurate overview this should be included in the first paragraph of section 7 alongside other methods

References supporting change: Baerlocher GM, Vulto I, de Jong G, Lansdorp PM. Flow cytometry and FISH to measure the average length of telomeres (flow FISH). Nat Protoc 2006; 1:2365–2376. https://www.nature.com/articles/nprot.2006.263#B23

JLRD309 (talk) 18:23, 20 July 2020 (UTC)

 Done Natureium (talk) 21:46, 4 August 2020 (UTC)

Layman

I feel like Wikipedia is more for the average user. If you hadd a doctorate, you wouldn't be brushing up on Wikipedia. I don't feel it necessarily needs to be an entire lesson, but I do wish this was explained in a manner that those who aren't accustomed to the language used can understand. This goes for most scholarly articles above high school level, but you have to start somewhere. I'm not the best to write it as I've been out of school too long. Just a thought, so if this is to be disregarded, that's fine, too. ScotChatterson (talk) 04:12, 19 October 2021 (UTC)

I do understand half of it, by the way. ScotChatterson (talk) 04:13, 19 October 2021 (UTC)

I suppose I'm referring to the "Structure and Function" section. ScotChatterson (talk) 04:18, 19 October 2021 (UTC)

Wiki Education Foundation-supported course assignment

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Sgilpin4.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 10:49, 17 January 2022 (UTC)

Wiki Education Foundation-supported course assignment

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Peer reviewers: M bartolo.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 10:49, 17 January 2022 (UTC)