Genetics Intelligent Design News

Jumping genes, a mechanism of minor evolutionary change

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Barbara McClintock, 1983

Further to how our bodies fight off jumping genes (trasposons), here’s an explanation of how they work:

Some of the most profound genetic discoveries have been made with the help of various model organisms that are favored by scientists for their widespread availability and ease of maintenance and proliferation. One such model is Zea mays (maize), particularly those plants that produce variably colored kernels. Because each kernel is an embryo produced from an individual fertilization, hundreds of offspring can be scored on a single ear, making maize an ideal organism for genetic analysis. Indeed, maize proved to be the perfect organism for the study of transposable elements (TEs), also known as “jumping genes,” which were discovered during the middle part of the twentieth century by American scientist Barbara McClintock. McClintock’s work was revolutionary in that it suggested that an organism’s genome is not a stationary entity, but rather is subject to alteration and rearrangement-a concept that was met with criticism from the scientific community at the time. However, the role of transposons eventually became widely appreciated, and McClintock was awarded the Nobel Prize in 1983 in recognition of this and her many other contributions to the field of genetics.

Also:

Transposable elements (TEs), also known as “jumping genes,” are DNA sequences that move from one location on the genome to another. These elements were first identified more than 50 years ago by geneticist Barbara McClintock of Cold Spring Harbor Laboratory in New York. Biologists were initially skeptical of McClintock’s discovery. Over the next several decades, however, it became apparent that not only do TEs “jump,” but they are also found in almost all organisms (both prokaryotes and eukaryotes) and typically in large numbers. For example, TEs make up approximately 50% of the human genome and up to 90% of the maize genome (SanMiguel, 1996).

Oh, by the way, this form of evolution does not turn a cob of corn into a monkey face orchid. It just shuffles stuff around.

Monkey Orchid

It’s just something that really happens in nature. McClintock here was apparently not an “aren’t I good?” girl.

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9 Replies to “Jumping genes, a mechanism of minor evolutionary change

  1. 1
    bornagain77 says:

    Transposable Elements Reveal a Stem Cell Specific Class of Long Noncoding RNAs – (Nov. 26, 2012)
    Excerpt: The study published by Rinn and Kelley finds a striking affinity for a class of hopping genes known as endogenous retroviruses, or ERVs, to land in lincRNAs. The study finds that ERVs are not only enriched in lincRNAs, but also often sit at the start of the gene in an orientation to promote transcription. Perhaps more intriguingly, lincRNAs containing an ERV family known as HERVH correlated with expression in stem cells relative to dozens of other tested tissues and cells. According to Rinn, “This strongly suggests that ERV transposition in the genome may have given rise to stem cell-specific lincRNAs. The observation that HERVHs landed at the start of dozens of lincRNAs was almost chilling; that this appears to impart a stem cell-specific expression pattern was simply stunning!”
    http://www.sciencedaily.com/re.....192838.htm

    Retroviruses and Common Descent: And Why I Don’t Buy It – September 2011
    Excerpt: If it is the case, as has been suggested by some, that these HERVs are an integral part of the functional genome, then one might expect to discover species-specific commonality and discontinuity. And this is indeed the case.
    http://www.uncommondescent.com.....nt-buy-it/

  2. 2
    gpuccio says:

    BA:

    “The retrovirus HERVH is a long noncoding RNA required for human embryonic stem cell identity”

    Nature Structural & Molecular Biology 21, 423–425 (2014)

    Abstract:

    “Human endogenous retrovirus subfamily H (HERVH) is a class of transposable elements expressed preferentially in human embryonic stem cells (hESCs). Here, we report that the long terminal repeats of HERVH function as enhancers and that HERVH is a nuclear long noncoding RNA required to maintain hESC identity. Furthermore, HERVH is associated with OCT4, coactivators and Mediator subunits. Together, these results uncover a new role of species-specific transposable elements in hESCs.”

    I would definitely say that “jumping genes” are a mechanism of major evolutionary change.

    It has been known for a long time that Epstein Barr virus, for example, can “immortalize” human B-cells.

    From:

    “Epstein-Barr Virus Immortalization of Human B-Cells Leads to Stabilization of Hypoxia-Induced Factor 1 Alpha, Congruent with the Warburg Effect”

    Plos one, July 27, 2012, DOI: 10.1371/journal.pone.0042072

    “Epstein-Barr virus (EBV) is a ubiquitous human gamma herpesvirus that causes lymphoproliferative disease in immunosuppressed patients and is associated with Burkitt’s lymphoma, Hodgkin’s lymphoma, other B- and T-cell lymphomas, nasopharyngeal carcinoma (NPC) and some gastric carcinomas [1]. EBV can infect B-cells in vitro and convert them into immortalized lymphoblastoid cell lines (LCLs). LCLs express six nuclear proteins (EBNA-1–6) and three latent membrane proteins (LMP-1, -2A and -2B). This growth transformation program is referred to as Latency III. Six of the proteins, EBNA-1, -2, -3, -5, -6 and LMP-1, are required for efficient B-cell transformation [1].

    Expression of the six transformation-associated proteins leads to extensive changes in cellular gene expression and signaling.”

  3. 3
    bornagain77 says:

    I disagree that “jumping genes”, though important for functionality, are a ‘mechanism of major evolutionary change’ since form is not reducible to DNA sequence in the first place as was clearly shown in ‘Darwin’s Doubt’

    Darwin’s Doubt narrated by Paul Giem – The Origin of Body Plans – video
    http://www.youtube.com/watch?l.....page#t=290

  4. 4
    gpuccio says:

    BA:

    Let’s say at least that they are a mechanism of major DNA sequence change. Again, I did not mention form or body plans.

    Maintaining stem cell status seems an important issue, I would say.

  5. 5
    bornagain77 says:

    Well gpuccio, obviously your claim was far more bold than than what you just stated. IMHO, you don’t have the evidence to make your case for CD. Moreover the trend in evidence is towards there never being a case for CD.

  6. 6
    Joe says:

    The cool thing about transposons is they carry within their sequence the coding for two of the enzymes required for them to “jump around”. And anyone who thinks that unguided evolution could do that is beyond reason.

  7. 7
    Mung says:

    Joe, given that God is not guiding evolution, what is the alternative to unguided evolution? Who, or what, is guiding evolution, if not God?

  8. 8
    Joe says:

    Mung, I never said anything about God guiding evolution. Is God guiding the operation of your computer? Does God guide genetic algorithms to their goal?

    What’s guiding evolution? Programming.

  9. 9
    Mung says:

    I understand that Joe.

    That’s why I lump you with the mechanists.

    Is ID a mechanistic theory?

    Why do young earth creationists adopt the same view of the created order as the atheists? Is it their theology?

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