- How we get new insects.
- Transgenic and paratransgenic insects differ significantly
in the way in which they are created, but the end results of their creation
are the same, insects with new characteristics (or in genetical terms -
phenotypes). In both cases, the new characteristics (phenotypes) of the
insects are the result of the manipulation of DNA by scientists in the
lab, and these new phenotypes are expressed in all insects descending from
- Transgenic insects are the product of the physical integration
of a piece of DNA manipulated in the laboratory (referred to generally
as the transgene) into the chromosomes of a target insect. The technical
issues, therefore, center around getting the DNA of interest to the chromosomes
of the target insect, promoting the integration of this extraneous piece
of DNA into the intact chromosomes and recognizing when you have actually
- Genetically altering an insect so that all of its descendents
will also be genetically altered requires that the initial integration
of the transgene occurs in the chromosomes of cells that will produce sperm
or eggs (most insect reproduction is sexual). The transgene must be delivered
not just to the cells of the gonads but into their nuclei (the central
compartment of cells containing chromosomes). Insect scientists accomplish
this by performing a very delicate microsurgical procedure involving the
physical injection of the transgene into the target cells of the host insect.
But, the chromosomes in the nuclei of cells are each single, contiguous,
very long strands of DNA. For a transgene to become part of a chromosome,
the chromosome must be completely broken into two pieces and the transgene
inserted into the resulting gap, and the gap must be completely repaired.
- This process occurs naturally, but very infrequently.
Insect scientists promote this fusion of chromosomes and transgenes by
attaching the transgene to additional DNA sequences called transposable
elements that have the unique capability of efficiently cutting and repairing
chromosomes. The unique sequences attached to the transgene (transposable
elements) essentially carry the transgene into the chromosome and are referred
to as vectors. Finally, the problem of recognizing a genetically altered
insect can be severe if the new phenotypes are not readily visible. Insect
scientists solve this problem by attaching a second transgene to the initial
vector-transgene combination that will result in new visible phenotypes
and permit the efficient identification of transgenic insects. Transgenes
used solely for assisting with the recognition of transgenic insects are
referred to as markers.
- Paratransgenic insects are not created by integrating
transgenes into the chromosomes of the target insect but into the microbes
that naturally inhabit their alimentary canal (gut). Genes expressed in
these gut symbionts can alter the phenotype of the host insect. The technical
issues focus on integrating the transgene into the chromosomes of the microbial
symbiont, reintroducing the symbiont into the host and promoting its transmission
to subsequent generations. Inserting transgenes into microbial symbionts
has relied extensively on existing microbial genetic technology. Insect
scientists have solved the problem of re-introducing the transgenic microbes
by first "curing" the host insect of its gut microbes and then
introducing them to the modified microbes. Limitations to the application
of paratransgenic technology center on the identification, isolation and
manipulation of appropriate microbial symbionts.
- Chromosomes -- long, continuous strands of DNA comprising
the genetic blueprint of the cell. Marker -- transgene that confers an
easily recognized, and usually visible, change in the phenotype of an organism.
Nucleus -- the central membrane-bound compartment of plant and animal cells
that contains the chromosomes. Paratransgenic Insect -- an insect containing
genetically altered microbial symbionts. Phenotype -- the physical characteristics
of an organism. Symbiont -- a microbe that lives in another organism in
a mutually beneficial relationship. Transgene -- a piece of DNA manipulated
in the lab and inserted into a host genome Transgenic Insect -- an insect
containing novel genetic material stably integrated into its chromosomes
and transmitted to its progeny. Transposable elements -- unique pieces
of DNA that naturally cut and paste themselves into chromosomes. Vector
-- refers to DNA that plays the unique role of carrying a transgene and
promoting its integration into chromosomes."
- For slides and biography of the Entomologist:
- The beginning of the alteration of nature and it's
lovely bugs. The devil is in the details: http://www.promega.com/applications/genexp_reptr/default.htm?WT.srch=1&src=google
- Altering Plants, grass, forests, and the companies involved:
Some scientists are concerned. SPEAKING OF MYSTERIOUS ILLNESSES!
- "....Risks are increased by the fact that the genes
inserted into GM food not only survive digestion, but transfer into body
organs and circulation.
- Transgenes have been found in the blood, liver, spleen
and kidneys.13 DNA can even travel via the placenta into the unborn.14
The only human clinical trial showed that transgenes from soy transfer
into intestinal bacteria.15 · Claims that no one has gotten hurt
from GM foods are misleading, since no one monitors human health impacts.
We do know that soya allergies skyrocketed by 50 percent after GM soybeans
were imported to the UK,16 and a GM food supplement killed about 100 Americans
and caused 5,000- 10,000 to fall sick.17
- · Some GM crops create their own pesticide called
Bt. Their approval relied on the assumption that Bttoxin is not bioactive
in mammals. But Bt-toxin caused powerful immune responses and abnormal
and excessive cell growth in mice. Filipinos living next to Bt cornfields
developed mysterious symptoms during the time of pollination - three seasons
in a row - and blood tests showed an immune response to Bt.18 A November
2005 report from India claims that Bt cotton also creates allergic responses.19
What if Bt genes transfer to gut bacteria like soya genes do? They could
turn our internal flora into living pesticide factories.
- Despite the Public Relation spin, GM crops increase the
use of herbicides20, lower average yield, and endanger food security. They
are detrimental to sustainable and organic farming, and trap farmers in
a cycle of indebtedness and dependence. They endanger biodiversity21, harm
beneficial insects22, damage soil bacteria23, contaminate non-GM varieties24
and may persist in the environment for generations.25"
- Fight back!
- Crossing the threshold!