The Trials of Amanda Knox and Raffaele Sollecito: Part 29

[Vixen]

Facts about saliva and blood:

Fact # 1: DNA in saliva is derived from both buccal epithelial cells and white blood cells.
It might surprise you to know that much confusion surrounds the real source of genomic DNA in saliva. Surprisingly, most people assume the source of DNA in saliva is strictly buccal epithelial cells. However, studies show that up to 74%[1] of the DNA in saliva comes from white blood cells which are an excellent source of large amounts of high quality genomic DNA. Yielding virtually the same amount of DNA per volume and the same DNA quality as blood, saliva can be considered equivalent to blood for genetic applications.

Blood collection is often considered the golden standard for DNA quality and it is an established practice across hospitals, clinics, and labs worldwide. However, many people don’t know that replacing blood with saliva is a proven option for genomic DNA analysis.

https://blog.dnagenotek.com/8-facts-most-people-dont-know-about-dna-from-saliva

As you see on the attached DNA plot, it shows Knox and Meredith Kercher's mixed DNA and tested for human blood. This was the sample from the cotton bud box where the blood was still dark before being diluted with water. The RFU's are higher still for the mixed pale pink diluted samples from the sink and bidet, which Stefanoni's assistant describes as one narrow streak leading from the side to the plughole.

 

[Vixen]

Ummm...viruses ARE germs:


http://sciencenetlinks.com/student-teacher-sheets/whats-germ/

Conti never said that in the Netflix film. This is what he said:



He most certainly never said " DNA is spread around 'like dust' every time we shake our hands" as you just claimed.

Conti then goes on to describe the ways in which the police and Stefanoni’s crew failed to follow many basic anti-contamination protocols. That is all he has to say about the DNA. But he does quote Cicero, which I think bears repeating: Any man is liable to err, only a fool persists in error





No one said that "you can catch something just by touching someone". Once again, either your reading comprehension is poor or you are deliberately misrepresenting what was said in an effort to boost your (false) claims. What we said was that germs can transfer through touch such as shaking hands.


https://www.cff.org/Life-With-CF/Da...-Healthy/What-Are-Germs/How-Are-Germs-Spread/




I really don't know why you find it so difficult to understand that the talcum powder is used to visibly demonstrate how DNA and germs can be passed from one person to another through touch. Of course, we have your claim that it can't but, then again, scientists and doctors say they can be transferred through touch. Who ya gonna believe? An accountant or actual forensic scientists and doctors? What a quandary.

Are you sure about that? Conti did indeed say it.

I can see you know little about pathology if you think you can catch disease from someone just by touching them. May I suggest you inform yourself?

 

[SpitfireIX]

Ha! Q.E.D ::

Instead of having the integrity to admit it, you pretend you no understand. Heap big confusion.

Why do you feel the need to write in the manner of stereotypical Native American English?

Further, every regular poster here is aware that Rolfe knows far more about biology than you could ever hope to. Fail.

 

[acbytesla]

Why do you feel the need to write in the manner of stereotypical Native American English?

Further, every regular poster here is aware that Rolfe knows far more about biology than you could ever hope to. Fail.

She tried to teach me about cellular communications. Even though I spent two decades working with and selling that equipment to telcos and corporations. This is par for the course.

 

[LondonJohn]

Are you sure about that? Conti did indeed say it.

I can see you know little about pathology if you think you can catch disease from someone just by touching them. May I suggest you inform yourself?

Holy cow. Of course you can catch diseases from someone "simply by touching them". Are you really that ignorant? Seriously? You genuinely never fail to surpass yourself with these statements of how-wrong-can-you-get; often, like this one, complete with patronising "I can see you know little about...." schtick added in for further unintended amusement.


(Obviously if you require a cite I can provide pages full of them. But this is like needing to provide a cite that London is the capital of the UK.....)



ETA: Oh and Conti did not ever say (or imply) "DNA is spread about like dust every time we shake our hands". Rather, he made the eminently correct observation that it is indeed possible to transfer DNA through processes such as shaking hands. Very different.

 

[LondonJohn]

Why do you feel the need to write in the manner of stereotypical Native American English?

Further, every regular poster here is aware that Rolfe knows far more about biology than you could ever hope to. Fail.

Exactly. And the biology relevant to this subject (and to this case in general) is readily available to anyone with a genuine desire for accuracy and truth, and the capacity to learn and to analyse rationally and objectively. In a way, one can understand how the partisan prosecutors got so much of this wrong in this case - whether wilfully or as a product of their innate bias and tunnel vision - but it's unforgiveable how the lower convicting courts got it so wrong as well (mainly by blindly taking the prosecution's (mis)interpretation uncritically at face value). Fortunately for justice (albeit grossly delayed), the Italian Supreme Court ultimately corrected the lower convicting courts. And frankly, in any serious, intellectually-honest debate about the case, it behoves all of us on all sides of the debate to be well-informed before offering up analysis.


If I write about a subject - whether scientific, legal/judicial or any other factual topic - I try to ensure I am fully appraised of, and educated in, the subject at issue before entering the debate. Especially when I write statements of alleged fact (but, frankly, even when I write something under the caveat of "I believe that" etc). And on those (rare) occasions when I'm factually wrong, I concede and educate myself. I most certainly don't try to double down on my own stupid.

But y'know, that's just me.........

 

[Rolfe]

I wonder what Vixen thinks the word "contagious" means? (Hint, the first four letters are the key.)

Part of my first lecture series to undergraduate animal science students, who can be surprisingly illiterate. Cont-agious diseases are diseases spread by cont-act. Many but by no means all are skin diseases.

(Actually that's diseases where you actually need contact to get transmission. Infectious disease in general isn't so fastidious, managing to get itself spread in air droplets, in the water, in food, hell, I had an entire lecture. But really, contact will do it for most things.)

 

[Stacyhs]

Are you sure about that? Conti did indeed say it.

Why yes, Vixen, I'm sure. Very sure. As you can see (or maybe not, apparently), I quoted Conti directly from the Netflix docu and it matches the pics you provided. Thank you for presenting them as evidence that what I quoted was accurate. Since you obviously failed to understand it the first time, here it is for you once again:

Let us be clear how easy it is to leave traces of DNA. If you move your hand on your arm, that small amount of fine dust those are all DNA traces which we spread within the area where we are in that particular moment. Therefore, a crime scene must be kept completely sterile. That is not what happened in this case.

Nowhere does Conti say, as you claimed, that " DNA is spread around 'like dust' every time we shake our hands". Once again, you misrepresent what was actually said.
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I can see you know little about pathology if you think you can catch disease from someone just by touching them. May I suggest you inform yourself?

Exactly where did I say any such a thing? Please quote me. But you can't because I never said that. I said, once again, that germs can transfer through touch such as shaking hands. Do I need to provide, yet again, the citations I provided earlier proving this?

May I suggest you take what Cicero said to heart:

"Any man is liable to err, only a fool persists in error"

 

[Stacyhs]

I wonder what Vixen thinks the word "contagious" means? (Hint, the first four letters are the key.)

Part of my first lecture series to undergraduate animal science students, who can be surprisingly illiterate. Cont-agious diseases are diseases spread by cont-act. Many but by no means all are skin diseases.

(Actually that's diseases where you actually need contact to get transmission. Infectious disease in general isn't so fastidious, managing to get itself spread in air droplets, in the water, in food, hell, I had an entire lecture. But really, contact will do it for most things.)

Exactly. For example:

Many illnesses spread through contact transmission. Examples are chicken pox, common cold, conjunctivitis (Pink Eye), Hepatitis A and B, herpes simplex (cold sores), influenza, measles, mononucleosis, Fifth disease, pertussis, adeno/rhino viruses, Neisseria meningitidis and mycoplasma pneumoniae.

https://dhss.delaware.gov/dph/files/directindtranspi.pdf


Expect to have Vixen tell you that you are ignorant and to educate yourself.

 

[Numbers]

Just delurking, as a specialist in blood analysis, to confirm that this is correct. Plasma has essentially no DNA and that's more than half of the total blood volume. Erythrocytes have barely a trace of DNA, and that's almost all the rest. The only DNA is in the buffy coat, the white cells, which is a line across a microhaematocrit tube between the plasma and the packed red cells, which is maybe 0.5 mm thick. Out of maybe a 5 cm blood column. Pretty much any other tissue in the body (with the exception of ocular fluid) has vastly more than this.

Are there mammalian species with DNA in their red cells (erythrocytes)?

How much DNA ,if any, is contained in human red cells?

 

[Stacyhs]

Red blood cells have no DNA.

Red blood cells do not have any DNA, as they lose their nuclei (the compartment in a cell that contains the DNA) as they mature. So the DNA in your blood is in your white blood cells. To get at it, scientists first spin a small sample of your blood at high speed, to separate the cells from the blood fluid.

http://whoami.sciencemuseum.org.uk/...whatisdnasequencing/wheredodnasamplescomefrom

 

[Rolfe]

Mature cells don't have nuclei but there is some DNA in immature cells. Someone who is anaemic might have a few nucleated red cells floating around. There's also mitochondrial DNA I think. But compared to tissues with normal nucleated cells it's only a trace.

Strictly, you're even going to get a trace even in plasma because of cellular fragments and so on. But again, relatively speaking, trace amounts.

 

[Planigale]

Are there mammalian species with DNA in their red cells (erythrocytes)?

How much DNA ,if any, is contained in human red cells?

No (though I may be corrected by the vet) mammalian red cells contain no DNA. Bird and reptile red cells do. (Actually a few immature mammalian erythrocytes are released from the bone marrow before they have dumped their DNA, so a small proportion of circulating red cells will contain decreasing amounts of DNA, that proportion varies and will be higher when the body makes lots of blood e.g. in anaemia due to blood loss.)

 

[Rolfe]

Red blood cells have no DNA.

http://whoami.sciencemuseum.org.uk/...whatisdnasequencing/wheredodnasamplescomefrom

That's kiddie-level stuff. Google "regenerative red cell picture" or "basophil erythroblast" or something like that to see nucleated red cells.

 

[Planigale]

Facts about saliva and blood:



https://blog.dnagenotek.com/8-facts-most-people-dont-know-about-dna-from-saliva

As you see on the attached DNA plot, it shows Knox and Meredith Kercher's mixed DNA and tested for human blood. This was the sample from the cotton bud box where the blood was still dark before being diluted with water. The RFU's are higher still for the mixed pale pink diluted samples from the sink and bidet, which Stefanoni's assistant describes as one narrow streak leading from the side to the plughole.

you are just so wrong about the RFU giving any indication about the source of DNA it is hard to know how to correct you. The RFU is a consequence of the concentration of DNA from the original sample, the amount collected, the efficiency of DNA extraction, the amount of extract introduced into the assay (e.g. Steffanoni had to use vacuum extraction to concentrate DNA from the knife - which on your argument means the DNA cannot be from blood), the number of replication cycles, inhibitors in the extract, the speed of injection, the setting of the spectrophotometer, the calibration. The RFU is not a measure of DNA in the original sample, it is an arbitrary and relative measure.

 

[Planigale]

That's kiddie-level stuff. Google "regenerative red cell picture" or "basophil erythroblast" or something like that to see nucleated red cells.

Try reticulocyte.

 

[Stacyhs]

you are just so wrong about the RFU giving any indication about the source of DNA it is hard to know how to correct you. The RFU is a consequence of the concentration of DNA from the original sample, the amount collected, the efficiency of DNA extraction, the amount of extract introduced into the assay (e.g. Steffanoni had to use vacuum extraction to concentrate DNA from the knife - which on your argument means the DNA cannot be from blood), the number of replication cycles, inhibitors in the extract, the speed of injection, the setting of the spectrophotometer, the calibration. The RFU is not a measure of DNA in the original sample, it is an arbitrary and relative measure.

Perhaps this is why Vixen has never presented evidence of her claim that high RFUs are associated with blood.

 

[Numbers]

Mature cells don't have nuclei but there is some DNA in immature cells. Someone who is anaemic might have a few nucleated red cells floating around. There's also mitochondrial DNA I think. But compared to tissues with normal nucleated cells it's only a trace.

Strictly, you're even going to get a trace even in plasma because of cellular fragments and so on. But again, relatively speaking, trace amounts.

No (though I may be corrected by the vet) mammalian red cells contain no DNA. Bird and reptile red cells do. (Actually a few immature mammalian erythrocytes are released from the bone marrow before they have dumped their DNA, so a small proportion of circulating red cells will contain decreasing amounts of DNA, that proportion varies and will be higher when the body makes lots of blood e.g. in anaemia due to blood loss.)

Rolfe and Planigale, thanks for your informative responses.

I have seen some references that state that a mature mammalian red blood cell (rbc) has no DNA because it has no nucleus and no mitochondria. The references claimed that immature rbc, prior to its release into the blood, loses its nucleus and all mitochondria. However, as pointed out in your posts, some - possibly a relatively small number - of immature rbcs may be released in some disease states, such as anemia.

It should be pointed out that any DNA from mitochondria would require specialized mitochondrial DNA profiling rather than the standard forensic test for nuclear DNA STRs; the mtDNA identifies the maternal ancestry of an individual but is not a unique personal identifier.

 

[Numbers]

Perhaps this is why Vixen has never presented evidence of her claim that high RFUs are associated with blood.

Also, saliva is as good a source of DNA as blood according to some research results, with a yield slightly higher than that of blood. See below for the abstract.

"BACKGROUND:

Saliva has been suggested as an attractive resource for evaluating physiological and pathological conditions in humans. This study aims to evaluate saliva sampling as an alternative to blood sampling for molecular testing.

METHODS:

We compared the yield, purity, and performance of DNA isolated from blood to that isolated from saliva using the non-invasive collection kit (Oragene DNA OG500 and OG575 kit). Saliva DNA was extracted by manual purification and QIAamp DNA mini kit. Blood DNA was isolated by salt-precipitation and DNAzol reagent. We also evaluated the quality of saliva DNA by PCR-based analysis.
RESULTS:

We found that the DNA yield from saliva (7.8 microg/0.5 mL saliva sample) from the manual purification method was comparable to the DNA yield from blood by the salt precipitation method (7.4 ug/0.5 mL blood sample). DNA extracted from saliva and blood were both of high purity (A260/280 > 1.70). Genotype results (PCR-RFLP and direct sequencing) for all sets of blood-saliva DNA samples were in 100% concordance.
CONCLUSIONS:

Saliva samples, when extracted by the manual purification method, provide a similar amount of human DNA as compared to the amount obtained from blood. Saliva is a viable alternative DNA source for genotyping studies."

Source: https://www.ncbi.nlm.nih.gov/pubmed/22582505

 

[Stacyhs]

Holy cow. Of course you can catch diseases from someone "simply by touching them". Are you really that ignorant? Seriously? You genuinely never fail to surpass yourself with these statements of how-wrong-can-you-get; often, like this one, complete with patronising "I can see you know little about...." schtick added in for further unintended amusement.


(Obviously if you require a cite I can provide pages full of them. But this is like needing to provide a cite that London is the capital of the UK.....)



ETA: Oh and Conti did not ever say (or imply) "DNA is spread about like dust every time we shake our hands". Rather, he made the eminently correct observation that it is indeed possible to transfer DNA through processes such as shaking hands. Very different.

Now, now...remember that this came from the same person who told us that murderers never admit to murder.