Introduction
Through the application of biotechnology,
it has become apparent that interspecies gene transfer between
unrelated organisms may be occurring naturally. Researchers have
thoroughly demonstrated that prokaryotic and eukaryotic cells
will uptake and incorporate foreign DNA from any other organism.
If the genetic material is inserted adjacent to the necessary
upstream regulatory sequences, then expression of foreign genes
will also occur. As this process is performed by the host cell,
and can not occur otherwise, it therefore exists by design, and
presumably for the purpose of allowing organisms to steal genes
or nucleotide sequences from others. The ramifications expressed
as evolutionary potential are enormous.
Genetic Transformations
Biotechnologists have developed gene transfer
techniques over the past couple of decades by trial and error.
Although the co-cultivation of cells with DNA is all that is
required, most techniques expose tissues to stresses which would
breech the plasma membrane, and or cell wall in the case of plants.
Following this exposure; some of the cells will possess the foreign
DNA in their genome.
Biolistics is probably the most commonly used technique
to genetically transfects cells.(Figure 1) The apparatus used is also affectionately
called the Gene Gun because it uses a high pressure delivery
system to blast gene-coated metal particles into plant or animal
tissue. Other procedures utilize electrical pulses, sonication,
or agitation with glass beads or fibers. All of these techniques
are simply used to improve the transformation efficiency by increasing
the frequency of contact between the foreign DNA and the would-be
host cell.
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Fig. 1. Gene Gun. Biolistics
or the "gene gun" is the most commonly used technique for performing
genetic transformations. It employs a high-pressure delivery system
to shoot tissue with gold or tungsten particles that are coated with
DNA. Although the gun's propulsion is now most typically
accomplished using a pressurized gas such as helium, the original
version of this system from Bio-Rad was equipped with a 22-caliber
pistol and blank cartridges. After being peppered with foreign DNA,
some of the cells will transport the sequences into the nucleus and
splice them into the genome. |
It is however, the recipient cell which
accepts the foreign DNA, protects it from degradation, transports
it through the nuclear membrane, and splices it into an unwound
section of chromosomal DNA where it becomes a permanent and heritable
addition to the genome. Given the nature of the techniques used,
it may also then be apparent that any abrasive exposure between
two organisms could provide the necessary contact for gene transfers
to occur.
Design and Genetics of Evolution
God is the ultimate genetic engineer, and
within our cells exists a molecular-machinery far beyond our
comprehension. Evolution occurs
by design through a history of genetic
recombination and natural selection. The genetic variability
that produced Darwin's finches was not introduced randomly during
replication errors, but instead specifically created by cellular
machinery. This has been thoroughly established by Mendelian
genetics, and the breeding histories of countless domesticated
animals, however whenever an evolutionist refers to the source
of genetic variability responsible for natural varieties it is
always attributed
to mutations.
The variations found among offspring from
the same parents are produced by recombination events performed
during gametogenesis, not random mutations, and it is from these
differences that nature selects and through which evolution occurs. We
do not yet understand exactly how these reactions are performed,
nor can we yet even determine how many subsequently occurred
during meiosis. All we know is that they indeed occur, and their
purpose is obviously to provide evolutionary potential, and allow
the creatures on earth to successfully occupy a variety of habitats.
It is pure naturalistic
assumption that mutations are creating new alleles. Following
division, there is however no way to determine if the changes
in the genome were the result of mutation or recombination, but
there is great reason to expect it to be the latter. The genome
is manipulated in two profound ways; one is the replication of
the genome, and the other is genetic recombination. It is well
known that replication is performed under rigid control, and
the cell possesses mechanisms to correct errors when they occur.
We also know that recombination intentionally changes the genome
of each gamete so no two cells are ever genetically identical.
It is well known fact that meiotic recombination is responsible
for the differences between sibling genomic DNA. It is likewise
well recognized that these same reactions have alone created
the variations of domestic breeds of dogs in only a few hundred
years, and yet the evolutionists continually claims mutations
are responsible for variations such as the finches on the Galapagos.
Genetic
recombination is being performed
by God's code editing machinery, and although these reactions
are almost totally uncharacterized, a limited ability is assumed
by both evolutionists and creationists alike. It is simply assumed
that recombination is only rearranging preexisting genes, and
replication errors are instead responsible for new genetic code.
The truth is however; recombination is intentionally modifying
genes to create the biochemical and phenotypic variability from
which nature selects. Likewise we can not rule-out the ability
of the cell to assemble new reading-frames or use foreign DNA
during genomic manipulations designed to promote evolution. Given
our present understanding, cellular genetic recombination remain
theoretically limitless, and is clearly responsible for variations
such as the finches just as they were the
domestic breeds.
Natural Interspecies Gene Transfer
The genome possessed by any individual
is essentially unique in all the world due to recombination,
and any specific lineage may be viewed as a sequence of reactions
that could never be reproduced verbatim. Likewise the adaptation
to a new or altered environment requires several generation.
It may therefore, serve us greatly to have a system that allows
an individual to acquire genetic material from others rather
than hoping they would be received from their parents.
Contrary to the opinions typical of creation
scientists,
the genome is not static, nor are organisms limited to the genes
they were created with in the beginning. Bacteria are widely
known to incorporate foreign DNA. Unfavorable conditions are
known to induce genetic recombination, and environmental stresses
such as nutrient deprivation will cause bacteria such as Bacillus
subtilis to take up exogenous DNA. If there is homology between
the foreign and their own chromosomal DNA, the bacteria will
integrate almost all of it into there genome through homologous
recombination where it can become a permanent part for all future
generations. (1)
New genes or alleles are also being assembled
during meiotic crossing-overs, and passed to the next generation.
God may also have provided each organism with the ability to
take advantage of the genetic material possessed by others. The
potential benefits are numerous, but the most obvious may be
the rapid acquisition of genes or polynucleotide compounds.
Following a lengthy history of struggle
in a particular region, organisms assemble useful sequences or
gene combinations. With each generation, the best-fitted offspring
selectively passes its combination of genes to the next. The
well adapted organism likely possesses specific required polynucleotide
strings that it might have spent generations perfecting under
selective pressure. Such regionally-specific genes can instead
be acquired through interspecies gene transfer, and the newcomer
may instead be able to essentially hi-jack genes from an unrelated
species after even chance contact.
Agrobacterium; Gene Thief and Biotech Engineer
Agrobacterium Tumerfaciens is a bacteria commonly used by biotechnology engineers
around the world to genetically transform plants. In nature,
this microbe is responsible for inducing a tumor-based pathogenesis
known as Crown-Gall disease pictured at right. The cancerous
growth is caused through the genetic transformation of the plant
by the microbe. Agrobacterium is not only a naturally
occurring interspecies genetic transformer, but some of the sequences
it is inserting were stolen previously from a plant at some point
in its history. The Agrobacteria is an excellent example
of interspecies gene transfer and genetic construction in action.
Through the transfer of a portion of plasmid
DNA called the T-DNA, the Agrobacterium forces the plant
cells to make an amino acid (opines) that only the bacteria can
metabolize as a fuel source. The single cell organism essentially
parasitizes the plant by inserting foreign DNA that the plant
translates into unusable protein. In addition to the genes that
code for opines, the Agrobacterium also inserts other genes to
cause a tumor or uncontrolled replication of transformed cells.
Perhaps
the most interesting aspect of this natural interspecies gene
transfer is the fact that the genes the bacteria is inserting
are under the control of plant regulators, and the tumor inducing
genes are not of a bacterial origin, but plant growth regulators.
The Agrobacterium is using genes to perform this parasitism
that it was likely not created with, but instead their very specific
use suggests that bacteria generally have the ability to assemble
DNA constructs through genetic recombination, and frequently
use foreign sequences during such procedures.
New Genetic Information
Although genetic recombination using native
sequences is probably the primary source of new alleles, we can
not rule out the possible acceptance and use of foreign DNA during
this process. Interspecies gene transfer is easily accomplished
in laboratory settings, and evidence from living populations
is also substantiating that horizontal movement of DNA is occurring
naturally and with some regularity.
The ability of cells to uptake and utilize
foreign DNA, and likewise the mechanisms to construct new genetic
information remains unrecognized by the majority of the creation science
community. The secular scientific community is similarly adamant
that all new genes are the
result of mutations, and refuse to acknowledge the intentional
role of genetic recombination
in the evolution or organisms.
The typical creationary view of evolution
is tainted by secular teachings concerning mutations. Likewise
the creationist has an overwhelming desire to argue evolution
which leads to a refusal to accept that new alleles are being
created through time. However, the molecular machinery creating
this new genetic information is still almost completely beyond
our comprehension, and has been designed by an intelligence that
will not allow us to presuppose limits upon these mechanisms.
The sources of new genes remains theoretical but clearly exist
by design, and may include the use of foreign DNA. Although these
matters may not be thoroughly elucidated within our lifetimes,
until such time they must remain theoretically limitless given
who designed the blueprints.
by Chris W. Ashcraft
Article References
1) Homologous
genetic recombination as an intrinsic dynamic property of a DNA
structure induced by RecA/Rad51-family proteins: a possible advantage
of DNA over RNA as genomic material. Proc. Natl. Acad. Sci.
U.S.A. 98, 8425-8432 (2001) Shibata, T., Nishinaka, T., Mikawa,
T., Aihara, H., Kurumizaka, H., Yokoyama, S. & Ito, Y.
3
Genome
fragment of Wolbachia endosymbiont transferred to X chromosome of host
insect. Natsuko Kondo, Naruo Nikoh, Nobuyuki Ijichi, Masakazu Shimada,
and Takema Fukatsu. Proc. Natl. Acad. Sci. U.S.A. 99(22):14280-14285
(2002)
This Section was Edited-out of "Genetic
Variability by Design"
The development of genetic transformation technology has illustrated
yet another function of HR. Through the application of biotechnology, it
has become clear that the typical genome is relatively flexible in size,
and will incorporate almost any extracellular DNA if there is sufficient
homology. For example, prokaryotes readily uptake foreign nucleotides
during times of stress, and all major taxa are able to exchange genes
across species barriers using HR. In fact, it was the genetic
transformation of bacteria in the late 1920's that finally led to the
discovery of DNA as responsible for the heredity of traits. All cell types
can now be genetically transformed in the lab with little difficulty, and
biotechnologists routinely use this ability to create genetically modified
organisms, such as herbicide or insect resistant crops. Many of the
procedures used to transfect plant and animal tissues with DNA will simply
stress the cells or breech the plasma membrane in the presence of the
desired genes.(Figure 3) Following these exposures, the cellular machinery
is exclusively responsible for transporting the DNA into the nucleus and
splicing it into the genome. Natural genetic transformations across
species barriers have also between reported. The adzuki bean beetle was
found to have incorporated genes from the endosymbiotic bacteria
Wolbachia., and there is also the well-known example of
Agrobacteria, which genetically transforms wounded plants creating a
tumor called Crown Gall disease.
News of Horizontal Gene Transfer