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acids circulating in the bloodstream and Darwin’s theory of pangenesis
age-old adage that you are what you eat has taken a literal turn in the rush of
startling findings since the human genome sequence was announced 10 years ago,
which overturn every tenet of the genetic determinist ideology that had made
the Human Genome Project seem a compelling undertaking (see [1, 2] Living with the Fluid Genome,
ISIS publications; Death of the
Central Dogma and other articles in the series, SiS 24).
In 2009, we reported on nucleic acids
circulating in the bloodstream that offer golden opportunities for disease
diagnosis, and may also play a role in communication between cells within an
organism  (Intercommunication
via Circulating Nucleic Acids, SiS 42).
But would circulating nucleic acids cross
species barriers? Yes, according to Liu Yongshen at the Henan Institute of
Science and Technology in Xinxiang, China . Furthermore, Charles Darwin was
really the first person to have proposed a mechanism for it in his theory of pangenesis.
Darwin’s theory of pangenesis suggested that
all cells of an organism shed minute particles, gemmules, which
circulate throughout the body and are passed on to the next generation through
the germ cells. In that way, the characteristics of the parents are passed on
to their offspring. And if the cells of the parents undergo changes during
their life time, those changes would also be transmitted to the offspring.
Liu described Darwin’s theory of pangenesis in some detail and reviewed both
historical and more recent evidence in support of it, including fascinating
findings on transmission of characteristics through blood transfusion that have
been expurgated from the mainstream account. He concluded that : “a
considerable revision of views on Darwin’s Pangenesis must occur before a new
comprehensive genetic theory can be achieved.”
Now, a team of researchers in China have documented just this possibility. Plant nucleic acids are found to survive digestion
in the gut, escape into the bloodstream, and taken up into the liver cells to
target a very specific gene for silencing .
a new class of signalling molecules between cells
Chen-Yu and colleagues at Nanjing University, National University of Defence
Technology, Changsha, and Tianjin Medical University, have been researching
stable microRNAs, which they found circulating in the bloodstream of mammals
that are actively secreted from the tissues and cells in the body. In a paper
published in 2008 , the team presented results suggesting that the miRNAs
could serve as a
novel class of biomarkers for disease, and later showed that they could act as
signaling molecules in intercellular communication .
MicroRNAs (miRNAa) are a class of 19-24
nucleotide long non-coding RNAs that silence an estimated 30 percent of
protein-coding genes in mammals after the genes are transcribed. They do so by
pairing, usually with complementary sequences in the 3’ untranslated regions
(UTRs) of the targeted gene transcripts. The targeted genes are involved in a
range of vital functions including cell differentiation, apoptosis (programmed
cell death), cell proliferation, the immune response, and the maintenance of
cell and tissue identity. Dysregulation of miRNAs is linked to cancer and other
diseases; and specific miRNA profiles in the blood are potential biomarkers for
Zhang and colleagues had characterized
the possible carriers of circulating miRNAs as microvesicles (MVs) shed from almost
every cell type under both normal and pathological conditions (rather like
Darwin’s gemmules). The MVs carry surface receptors and ligands of the original
cells and have the potential to selectively interact with specific target cells
to transport lipids, mRNA, proteins, or other signalling molecules between
cells. Many MVs also contain miRNAs that could be selectively packaged and
delivered into recipient cells where they regulate the expression of target
genes and recipient cell function. In other words, miRNAs can serve as a novel
class of signalling molecules between cells in the same organism.
To their surprise, Zhang and colleagues
found plant miRNAs in the serum and plasma of humans and other mammals .
More than half of the plant miRNAs detected are present in MVs. In an extensive
series of experiments, they showed that a particularly abundant plant miRNA,
MIR168a, can pass through the mouse gut and enter the bloodstream, ending up in
various organs especially the liver, where it regulates a specific protein,
LDLRAP1, involved in low density lipoprotein uptake.
miRNAs detected in the blood of healthy Chinese adults and in animals
investigating the global miRNA profile in human serum, Zhang and colleagues
consistently found plant miRNAs in healthy Chinese men and women. Sequencing
revealed ~30 known plant miRNAs in Chinese healthy subjects, among which
MIR156a and MIR168a were most abundant, and most likely originate from rice
eaten by all the subjects. Plant miRNAs were also detected in the serum of
other animals such as calves. Plant miRNAs are generally present at one-tenth
the level of the most abundant endogenous mammalian miRNAs; and their presence has
been confirmed by reverse-transcription PCR and northern blotting. Plant miRNAs
are 2’-O-methylated on their terminal nucleotide, which makes them resistant to
periodate treatment. In contrast mammalian miRNAs with free hydroxyl groups are
sensitive to periodate. This is a further method for distinguishing between
plant and animal miRNAs. Whereas MIR156a and MIR168a in rice and serum are
highly resistant to periodate, the mammalian miR-16 in liver and serum was
oxidized and not detectable after periodate treatment.
miRNA in food can pass through the mouse gut and enter the serum and organs
mice, MIR168a and MIR156a were detected in various tissues including liver,
small intestine and lung, while MIR166a, another plant miRNA could not be
detected in the mouse tissues, although it was present in the serum.
The ordinary chow diet of mice had
MIR168a, MIR156a and MIR166a at concentrations less than 1 fm/g (fm, femtomole,
is 10-15mole), but 3-10 times as high in fresh rice. The same plant
miRNAs are also present in Chinese cabbage, wheat and potato, and are not
destroyed by cooking.
Mice fed the chow diet did not show
elevated levels of MIR168a and MIR156a. In contrast, the plant miRNAs were
significantly increased in both the sera and livers of mice fed with fresh rice
for at least 6 h afterwards. It appears that only the mature single-stranded
MIR168a was taken up into the blood stream, as precursors and double-stranded
forms fed to mice could not be detected in the serum afterwards. Plant miRNAs,
being 2’-O methylated, are also protected from acid degradation in the
mammalian gene silenced by rice MIR168a
that functional plant miRNA in food can enter the bloodstream of mammals, Zhang
and colleagues wanted to know if it can also silence mammalian genes, the same way
it silences plant genes. A bioinformatics analysis identified 50 genes that
might be the target for MIR168a silencing in mouse, human and rat genomes. The
most highly conserved sequence is located in exon 4 of the low-density
lipoprotein receptor apoprotein 1 (LDLRAP1) LDLRAP1 is enriched in the liver,
where it plays a critical role in the removal of low density lipoprotein (LDL)
of HepG2 cells (a liver carcinoma cell line) with the precursor of MIR168a
resulted in 1 000 fold elevation in MIR168a, indicating that the precursor can
be processed to mature MIR168a in the liver. Concomitantly, the LDLRAPI protein
was significantly reduced, but the mRNA level was not affected, consistent with
MIR168a acting post-transcriptionally to silence the mRNA. The binding of
MIR168a to the LDLRAPI coding sequence was confirmed by a luciferase reporter
assay, in which a mutant or wild-type human LDLRAPI exon 4, and the human
LDLRAPI coding sequence were cloned into a luciferase reporter plasmid and
transfected into HEPG2 cells together with pre-MIR168a. As expected, luciferase
activity for wild type was significantly reduced through MIR168a binding, where
the mutant luciferase activity was not affected.
cells take up MIR168a and package it for transport
possibility that the epithelial cells lining the intestine could take up the
plant miRNA and package it into microvesicles (MVs) for transport was
investigated in human intestinal Caco-2 cells, which were transfected with
single-stranded mature MIR168a and the MVs released were collected and added to
The level of MIR168a was boosted 200-fold
in Caco-2 cells after transfection, and rose 100-fold in HepG2 cells treated
with the MVs released from Caco-2 cells. As a result, the LDLRAP1 protein in
the HepG2 cells was significantly decreased, without affecting the LDLRAP1 mRNA
level. Repression of LDLRAP1 expression in the HepG2 cells was dose dependent,
as Caco-2 MVs containing more MIR168a correspondingly led to greater depression
of LDLRAPI protein levels.
The protein Argonaute 2 (AGO2) is present
in MVs and facilitates miRNA binding to its target gene via the RNA-induced
silencing complex (RISC) (see  Subverting
the Genetic Text, SiS 24). To see if plant MIR168a is associated
with mammalian AGO2 and LDLRAPI mRNA, the researchers used anti-AGO2 antibody
to precipitate the protein from HEPG2 cells treated with Caco-2 MVs. They
detected both MIR168a and LDLRAP1 mRNA together with the AGO2.
inhibits mouse liver LDLRAPI expression and increases plasma LDL-cholesterol
density lipoprotein (LDL) is the major cholesterol-carrying lipoprotein in
human plasma, and is generally believed to play an essential role in
pathogenesis of atherosclerosis (hardening of the arteries). However, the
connection between cholesterol and atherosclerosis is tenuous . Instead,
substantial evidence has emerged that it is the oxidation of LDL triggering the
inflammation response that’s responsible for atherosclerosis . The probability
of oxidation increases with time of circulation in the bloodstream, which is
why LDLRAPI is important for clearing it LDL from circulation.
were fed with chow or fresh rice for 7 days after 12 h fasting . There was
no difference in body weight although the rice-fed group ate more. The serum
level of MIR168a in the chow-fed group was not significantly altered, while the
rice-fed mice had significantly increased levels of MIR168a circulating in
serum over the entire period. Levels of MIR168a in the liver similarly, were
increased in rice-fed mice over chow-fed controls after 1 day.
Concomitantly, LDLRPI expression
decreased dramatically in the rice-fed mice after 1 day, while LDL levels in
plasma were significantly elevated on days 3 and 7. Interestingly, the level of
liver LDLRAPI was not related to the levels of plasma cholesterol or
triglycerides. If anything, plasma cholesterol level was decreased, while ApoA,
the protein in LDL, and triglycerides were unchanged.
implications for health, especially of GM food and feed
findings of Zhang’s team  have profound health implications for food. Food provides not just energy, building blocks, and
the usual vitamins and minerals, but also ‘informational’ nucleic acid
molecules across kingdoms that influence the expression of our genes. Group
leader Zhang is quick to agree with me  that their study says nothing about
the health of rice, and definitely not that rice is bad for health. After all,
healthy Chinese men and women all have plant miRNA circulating in their
bloodstream. What it does reveal is the intimate relationship between our
traditional diet and our biology, which have co-evolved and co-adapted for
millennia, if not longer. We are, to quite an extent, what we eat. A staple,
such as rice, is particularly important, as it forms the major part of the diet,
and hence deeply embedded in our physiology.
raises the key question on the safety of genetically modified (GM) food, which
Prof. Zhang has declined to comment on.
have previously warned of the potential dangers of circulating nucleic acids .
Most relevant to the new findings of Zhang’s team is an experiment in gene
therapy using a precursor of miRNA. It turned out to have so many off-target
effects that it killed more than 150 of the experimental mice (see  Gene Therapy Nightmare for
Mice, SiS 31).
Genetic modification of plants and
animals is notorious for being completely unpredictable and uncontrollable, as
well as unstable (see  FAQ on
Genetic Engineering, ISIS tutorial). That applies to new and unpredictable
complement of miRNAs that could result, to which humans (as well as other
animals) are totally unprepared. It could account for some of the illnesses and
deaths observed in the field as well as in lab experiments [13, 16] (see GM Science Exposed, ISIS e-book).
The miRNA profiles of all GM food and
feed need to be carefully documented now, especially if proponents are still
intent on introducing them into our food chain in the face of all the damning
evidence on health and environmental impacts.
Prof Frances Burton Comment left 30th November 2011 21:09:52 The field of epigenesis, while dating to Waddington in the 1960s and 70s, really took off at the beginning of this century, and now has burgeoned into a major interest of genetics. The now-known fact that environmental substances affect genetic expression is of paramount importance,and undoubtedly had its effect on our ancestors. In my book, FIRE: THE SPARK THAT IGNITED HUMAN EVOLUTION, I speculated that early hominins were able to associate with fire, and in so doing exposed themselves to the LIGHT emanating. This light affected circadian rhythms through the melatonin pathway, as well as other hormonal systems detailed in my book.
Todd Millions Comment left 3rd December 2011 22:10:16 Dr Mae-Wan Ho
Thanx for this.Such a continent this shore becomes.
On both these rna circulating fragments and the rest of any organisams DNA-RNA -zoo.Are referent materials from before GM modification even available for comparision?Stored suitably,by whom?
I would have some concern that samples could be switched,too make it appear that escapes had always being part of a genome.
Sharlene Comment left 4th December 2011 09:09:59 I applaud your work in this area. I know that our food source,especially gm foods are altering our bodies. I have an extreme case of morgellons disease and have been tested positive for agrobacteria tumefaciens. I have also produced actual plants,pods and insects in my body.I have thousands of photos of these abberations. I will be so thankful when the truth comes out about our food supply.I hope it is exposed and stopped before it is too late. Thank you for being brave enough to speak up with the facts.
Mae-Wan Ho Comment left 4th December 2011 09:09:55 Hi Todd,
Yes, there is a lab in Europe that is supposed to collect standard materials deposited by companies. Yes, companies have been allowed to change their standards when it became clear that the GMO has mutated from its original state, or turned out not to match what the company had described when checked by other scientists. I have been challenging companies to prove that their GMOs are genetically stable, and as yet received no proof, or answer. Transgenic instability multiplies unknown upon unknown. That is why people like myself want nothing more to do with GMOs.