Wednesday, May 23, 2012

BURDENING THE SPECIES WITH GENETIC MUTATIONS: WE ARE ALREADY DOING IT


In 1956 a group of geneticists issued a report concerning effects of radioactivity on hereditary. The New York Times published the report on June 13, page 18.

The report's authors were stars in the field of genetics and included President of the National Academy of Sciences Dr Detlev Bronk; Dr. A. Geoffrey Norman, Chairman of the Committee of the Effects of Atomic Radiation on Agriculture and Food Supplies; Dr. Henry Wexler, Chairman of the Committee on Metrological Aspects of Atomic Radiation; Dr. Shields Warren, Chairman of the Committee on the Pathological Effects of Radiation; Dr. Abel Wolman, Chairman of the Committee on the Disposal and Dispersal of Atomic Waste; Dr. Roger Revelle, Chairman of the Committee on Oceanography and Fisheries. 

The report begins by diplomatically acknowledging the medical and energy benefits of nuclear. It then turns to examine the health risks, particularly from “fall-out.”

The report queries:

[Excerpt] “Are we harming ourselves and are there genetic effects which will harm our children and their descendants, through this radioactive dust that has been settling down on all of us? Are things going to be still worse when presently we have a lot of atomic power plants, more laboratories experimenting with atomic fission and fusion, and perhaps more and bigger weapons testing? Are there similar risks, due to other sources of radiation, but brought to our attention by these atomic risks?

The report continues that “even very small amounts of radiation unquestionably have the power to injure hereditary materials.”


Majia Here: The report was created in the early days of genetic research. However, the report authors expressed confidence in their conclusions because of the similarities across animal genomes that reproduce sexually. Thus, the report notes that although research to date on radiation’s biological effects were (primarily) limited to bacteria, fruit flies and mice, 

[Excerpt] “the chemical nature of hereditary material is universally the same; the main pattern of hereditary transmission of traits is the same for all life reproducing sexually; and the nature of the effects of high energy radiations upon the genetic material is likewise universally the same in principle. Hence when it comes to human … we can at least feel certain of the general nature of the effects, and need only to discover ways in which to measure them precisely..."

The report is pages long so I will summarize the main conclusions.

First, the report addresses how genetic mutations occur to individuals exposed to any level of radiation, including background radiation:

[Excerpt] "...it cannot safely be assumed that the effect is a negligible one on the person in whom the mutation occurred, nor can it properly be said that this effect is nongenetic even though passage to offspring is not involved. For various kinds of cellular abnormalities are known to be perpetuated within an individual through body-cell divisions; so these effects are genetic in the broad sense.
What is involved here is not only mutant genes, but also larger scale disruptions of the genetic material, such as breakage of chromosomes.
 
The quantitative relations are not yet clear, but it is established that certain malignancies such as leukemia and certain other cellular abnormalities can be induced by ionizing radiations."

MAJIA HERE: After discussing the implications for individuals, the report discusses what happens when genetic mutations affect germ-line cells involved in reproduction. This is the central concern of the report because enough mutations to human germ line cells can effectively compromise the species' ability to produce healthy offspring.

Let me put this another way: The report is warning readers that too much exposure to radiation can cause the extinction of the human species.

[Excerpt] "To return to a consideration of the risks which are passed on to progeny, the mutant gene may exist in a sperm or an egg cell as a result of a mutation having occurred either in that cell or at some earlier cell stage. In this case, a child resulting from this sperm or egg will inherit the mutant gene….
 
…. Of great importance for our present study is the fact that mutant genes—genes which have, for example, been changed by radiations—are usually of the recessive types.
 
It is now easy to see that any organism may have, latent in its genetic constitution, ineffectual or recessive genes that have not had much of a chance to become apparent in its developed external characteristics since the recessive genes are masked by their dominant companion genes…
 
…Mutation ordinarily affects each gene independently; and once changed, an altered gene then persists from generation to generation in its new or mutant form.
 
Moreover the mutant genes, in the vast majority of cases, and in all the species so far studied, lead to some kind of harmful effect. In extreme cases the harmful effect is death itself, or the loss of the ability to produce offspring, or some other serious abnormality. What in a way is of even greater ultimate importance, since they affect so many more persons, are those cases that involve much smaller handicaps, which might tend to shorten life, reduce number of children, or be otherwise detrimental” [end excerpt]


MAJIA HERE: The report explains that mutant genes may not be expressed in the first generation of offspring. However, once they are encoded into the germ-line cells they get transmitted across generations.

CONSEQUENTLY, each new generation of offspring will receive every mutation their parents ever incurred to their germ-line cells. In effect, each generation is BURDENED with the LEGACY OF MUTATIONS TO GERM LINE CELLS incurred by previous generations.

[Excerpt] "the harmful recessive mutant genes are not usually completely masked. Even when paired with a normal and dominant gene, that is to say even when in the heterozygous state, they still have some detrimental effect. This ‘heterozygous damage’ is ordinarily much smaller than the full expression of the mutant when in the homozygous state, and yet there may be significant shortening of the length of life or reduction of the fertility of the heterozygous carriers of the mutant. And the risk of heterozygous damage applies to every single descendant who receives the genes....”

"...A mildly deleterious gene may eventually do just as much total damage as a grossly and abruptly  one, since the milder mutant persists longer and has a chance to harm more people”

"....the concept of a safe rate of radiation simply does not make sense if one is concerned with genetic damage to future generations. What counts, from the point of view of genetic damage, is not the rate; it is the total accumulated dose to the reproductive cells of the individual from the beginning of his life up to the time the child is conceived...." [end excerpt]

MAJIA HERE: After discussing at length the mechanisms whereby genetic mutations caused by radiation are transmitted generationally, the report notes that measuring these changes in the entire population is quite difficult. But:

[Excerpt] “We should not disregard a danger simply because we cannot measure it accurately, nor underestimate it simply because it has aspects which appeal in differing degrees to different persons...."

MAJIA HERE: I think it is very important to address the message here: 

This report is warning the public that at some unknown level of exposure, say X, humans will have such a legacy of genetic damage that their offspring are not able to successfully reproduce.

There is considerable research now pointing to the role of de novo mutations in autism.

Here is a definition of a de novo mutation: "An alteration in a gene that is present for the first time in one family member as a result of a mutation in a germ cell (egg or sperm) of one of the parents or in the fertilized egg itself " (Genetics Homepage Reference http://ghr.nlm.nih.gov/glossary=denovomutation)

Majia here: It appears that we are on the fast track for burdening our descendents with genetic mutations so great in number that the species may not perpetuate.

FUKUSHIMA radiation is elevating background levels of radiation substantially and contaminating food supplies in the northern hemisphere, particularly in Japan, Canada, and the US. 

We must act now to address the fallout and to shut down nuclear reactors everywhere that are routinely leaking tritium and other forms of ionizing radiation.

 





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