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Date:

November 8, 2000

Subject:

Horizontal gene transfer and NZ Royal Commission

 

Dear All,



You may all be aware that New Zealand is currently in the process of a
Royal Commission into deciding whether to allow further research into
GMO's, whether to allow any more field trials, labelling etc.

As part of that process they are requesting expert witness statements
from around the globe and guess what? Mae-Wan Ho has offered her expert
opinion on this matter. I think I have said enough about Dr. Ho for now
but another witness putting the case against GM technology has also put
his hand up.


Dr Peter Wills is an Associate Professor of Physics at the
University of Auckland. He is also a Theoretical Biologist and has
published widely.



Dr Wills is an ardent opponent of GM and was New Zealand
Chairman of Greenpeace for 4 years. His evidence to the New Zealand
Royal Commission on Genetic Modification will be given on Monday 13
November. His testimony can be viewed at the following site.
0000,0000,fefehttp://www.lifesciencenz.com/repository/information/wb_wills1.pdf


In response to Dr Wills, Dr. David Tribe of the University of Melbourne
and Dr. Roger Morton of CSIRO Plant Industry (as well as those sources
cited) have produced an outstanding reply which I have posted to
AgBioView with Dr. Tribe's permission. It follows:



The whole basis of Wills'main biological argument is incorect biological
reasoning. Wills is highly selective in his discussion of known
experimental and observational biology, and avoids mentioning or
analysing a huge amount of empirical observations of natural,
unpredictable random DNA arrangements that occur repeatedly in natural
evolution (summarised below). These omitted observations conflict
emphatically with his misleading innacurate generalisations about
biology.


Wills states for example :

right,left"59 There is no basis in either
theory or observation for the assertion that patterns of genetic

change effected by genetic engineering are of the same character, in
respect of their effect

on ecosystem dynamics and adaptation, as past evolutionary patterns of
genetic change."



This statement is false and ignores the many arguments and studies
showing similarities between natural horizontal gene movement
(cross-species gene movement) and natural DNA rearrangements (Random
mutational Insertion) and those used in the laboratory. Selected
examples that disprove his erroneous assertion "There is no basis in
either theory or observation " include the following:


GENES MOVE AROUND MANY MICROBES:

J Mol Microbiol Biotechnol 1999 Aug;1(1):45-50

Microbial gene transfer: an ecological perspective.

Paul JH

Microbial gene transfer or microbial sex is a means of exchanging loci
amongst prokaryotes and certain eukaryotes.

Historically viewed as a laboratory artifact, recent evidence from
natural populations as well as genome research HAS INDICATED

THAT THIS PROCESS MAY BE A MAJOR DRIVING FORCE IN MICROBIAL EVOLUTION.
Studies with natural populations have taken two

approaches- either adding a defined donor with a traceable gene to an
indigenous community, and detecting the target gene in

the indigenous bacteria, or by adding a model recipient to capture genes
being transferred from the ambient microbial flora.

However, both approaches usually require some cultivation of the
recipient, which may result in a dramatic underestimation

of the ambient transfer frequency. Novel methods are just evolving to
study in situ gene transfer processes, including the use

of green fluorescent protein (GFP)-marked plasmids, which enable
detection of transferrants by epifluorescence microscopy.

A TRANSDUCTION-LIKE MECHANISM OF TRANSFER FROM VIRAL-LIKE PARTICLES
PRODUCED BY MARINE BACTERIA AND THERMAL SPRING BACTERIA

TO ESCHERICHIA COIL HAS BEEN DOCUMENTED RECENTLY, INDICATING THAT BROAD
HOST RANGE TRANSDUCTION MAY BE OCCURRING IN AQUATIC

ENVIRONMENTS. The sequencing of complete microbial genomes has shown that
they are a mosaic of ancestral chromosomal

genes interspersed with recently transferred operons that encode
peripheral functions. Archaeal genomes indicate that the

genes for replication, transcription, and translation are all eukaryotic
in complexity, while the genes for intermediary

metabolism are purely bacterial. And in eukaryotes, many ancestral
eukaryotic genes have been replaced by bacterial genes

believed derived from food sources. Collectively these results indicate
that microbial sex can result in the dispersal of loci in

contemporary microbial populations as well as having shaped the
phylogenies of microbes from multiple, very early gene

transfer events.


FUNGAL GENES (GROUP I INTRONS) MOVING INTO MANY FLOWERING PLANTS

Proc Natl Acad Sci U S A 1998 Nov 24;95(24):14244-9

Explosive invasion of plant mitochondria by a group I intron.

Cho Y, Qiu YL, Kuhlman P, Palmer JD


Group I introns are mobile, self-splicing genetic elements (GENES) found
principally in organellar genomes and nuclear rRNA

genes. The only group I intron known from mitochondrial genomes of
vascular plants is located in the cox1 gene of

PEPEROMIA, WHERE IT IS THOUGHT TO HAVE BEEN RECENTLY ACQUIRED BY LATERAL
TRANSFER FROM A FUNGAL DONOR.

Surveys of 335 diverse genera of land plants now show that this intron
is in fact widespread among angiosperm cox1

genes, but with an exceptionally patchy phylogenetic distribution. Four
lines of evidence-the intron's highly disjunct

distribution, many incongruencies between intron and organismal
phylogenies, and two sources of evidence from exonic

coconversion tracts-lead us to conclude that the 48 angiosperm genera
found to contain this cox1 intron acquired it by 32

separate horizontal transfer events. (THAT IS TO SAY GENE MOVEMENT
BETWEEN SPECIES).Extrapolating to the over 13,500 genera of angiosperms,
we estimate that this intron

has invaded cox1 genes by cross-species horizontal transfer over 1,000
times during angiosperm evolution. This massive

wave of lateral transfers is of entirely recent occurrence, perhaps
triggered by some key shift in the intron's invasiveness


CROSS SPECIES GENE MOVEMENT IN INSECTS EXEMPLIFIED BY MOBILE GENES CALLED
TRANSPOSONS

Mol Biol Evol 1995 Sep;12(5):850-62

Recent horizontal transfer of a mariner transposable element among and
between Diptera and Neuroptera.

Robertson HM, Lampe DJ


Transposable elements of the mariner family are widespread among insects
and other invertebrates, and initial analyses of

their relationships indicated frequent occurrence of horizontal transfers
between hosts. A specific PCR assay was used to

screen for additional members of the irritans subfamily of mariners in
more than 400 arthropod species. Phylogenetic

analysis of cloned PCR fragments indicated that relatively recent
horizontal transfers had occurred into the lineages of a

fruit fly Drosophila ananassae, the horn fly Haematobia irritans, the
African malaria vector mosquito Anopheles gambiae,

and a green lacewing Chrysoperla plorabunda. Genomic dot-blot analysis
revealed that the copy number in these species

varies widely, from about 17,000 copies in the horn fly to three copies
in D. ananassae. Multiple copies were sequenced

from genomic clones from each of these species and four others with
related elements. These sequences confirmed the

PCR results, revealing extremely similar elements in each of these four
species (greater than 88% DNA and 95% amino

acid identity). In particular, the consensus sequence of the transposase
gene of the horn fly elements differs by just two

base pairs out of 1,044 from that of the lacewing elements. The mosquito
lineage has diverged from the other Diptera for

over 200 Myr, and the neuropteran last shared a common ancestor with them
more than 265 Myr ago, so this high

similarity implies that these transposons recently transferred
horizontally into each lineage. Their presence in only the

closest relatives in at least the lacewing lineage supports this
hypothesis. Such horizontal transfers provide an explanation

for the evolutionary persistence and widespread distribution of mariner
transposons. We propose that the ability to

transfer horizontally to new hosts before extinction by mutation in the
current host constitutes the primary selective

constraint maintaining the sequence conservation of mariners and perhaps
other DNA-mediated elements.


GENE MOVEMENTS IN INSECTS-A COMPREHENSIVE REVIEW DOCUMENTING EXTENSIVE
SIMILARITIES OF NATURE TO LAB GENETIC ENGINEERING

Annu Rev Entomol 1995;40:333-57

Distribution of transposable elements in arthropods.

Robertson HM, Lampe DJ


Transposable elements of the DNA-mediated and RNA-mediated classes found
in arthropods are briefly described and

their distribution reviewed. The distribution patterns of DNA-mediated
elements are extremely patchy and the principal

cause appears to be the horizontal transfer of elements between host
lineages. In the best documented case of mariner

elements, these hosts can be in different orders of insects, classes of
arthropods, and even other phyla of animals.

RNA-mediated elements appear to undergo much longer periods of vertical
evolution within host lineages, and evidence

for their horizontal transfer remains scant. The evolutionary
relationships of many of these transposons have recently

been illuminated by phylogenetic analyses of the reverse-transcriptase
enzymes of the RNA-mediated elements, and the

recognition that the transposases of some of the DNA-mediated elements
are distantly related to in the integrases of some

of the RNA-mediated elements.


MOBILE DNA (CALLED TRANSPOSONS or RETROELEMENTS) BEHAVIOUR IN PLANTS
SHOWS THAT , CONTRARY TO WILLS,

THAT THERE IS INDEED A BASIS for "change[s] effected by genetic
engineering [being] of the same character, in respect of their effect on
ecosystem dynamics and adaptation, as past evolutionary patterns of
genetic change"


Documentation is in the following is an excerpt from a recently published
review from the

Plant Cell (Heslop-Harrison Plant Cell 2000 12 (5): p617- ). As this
review points out such MOBILE DNA BLOCKS ARE found in all

plants already, in large numbers and are highly mutatagenic - for
plants.

If such DNA is a risk then we will have to stop consuming plants for
food. Unfortunately such DNA elements are also in animals so we can't eat
them either.


"As they insert themselves into the genome, retroelements act as
mutagenic agents" "Retroelements have been found in all plants
investigated" "Retroelements, typically including two or three open
reading frames ... and frequently represent half of the nuclear DNA"


Transposable Elements and Retroelements


Retroelements have been found in all plants investigated and are very

heterogeneous (Flavell et al. 1992 ), suggesting that they are an
ancient

component of genomes. They are generally dispersed over plant
chromosomes,

consistent with their mode of amplification, but may associate with

particular genomic regions.

As they insert themselves into the genome, retroelements act as mutagenic
agents, thereby providing a putative source of biodiversity (Hirochika
et

al. 1996 ; Heslop-Harrison et al. 1997 ; Ellis et al. 1998 ; Flavell et

al. 1998 ) and serving as markers of diversity. Regulatory mechanisms
mayact to protect genomes from insertional mutagenesis (Lucas et al.
1995), and it has been suggested that transgene-induced gene silencing
reflects mechanisms aiming to prevent genome invasion by retroelements.
Plant retrotransposon activity can be regulated at any step of the
replication cycle, including transcription, translation, reverse
transcription, nuclear import, and integration.


Along with DNA (class II) transposable elements and other elements such
as miniature inverted tandem elements (MITES; Wessler et al. 1995 ;
Casacuberta et al. 1998), insertion of retrotransposon elements can
inactivate or alter gene function (Wessler et al. 1995). Indeed,

transposition is estimated to account for 80% of the mutations detected
in Drosophila (Capy 1998). Transposons can excise, partially or
completely restoring gene function, and can also lead to chromosome
rearrangements such as inversions or translocations. Transposable
elements can also act to move elements such as exons and promoters into
existing sequences so as to create new gene functions and contribute to
evolution (Plasterck 1998 ; Moran et al. 1999). Indeed, retroelements are
activated under stressconditions (Wessler 1996 ; Grandbastien 1998 ;
Kumar and Bennetzen 1999 ; Walbot 1999 ). Alternative splicing of genes
caused by transposable

elements has been shown in maize (Bureau and Wessler 1994a , Bureau and

Wessler 1994b ). Methylation of retroelements can also affect adjacent

sequences and lead to transcriptional repression (Yoder et al. 1997 ;

Goubely et al. 1999 ).


Wills MAKES ANOTHER RELATED FALSE AND MISLEADING STATEMENT ABOUT BIOLOGY
LATER IN HIS DOCUMENT viz:


right,left"72 The argument concerning the
safety of genetic engineering in comparison with selective

breeding is similarly spurious. Any new hazards (whether to consumers or
within the

ecology of the organism in question) associated with the new
constellations of genes that

can arise as a result of selective breeding are limited to those that can
propagate by

means of the similarities between organisms that allow them freely to
exchange genetic

material - sexual reproduction essentially."



This statement is misleading in that it assumes that sexual recombination
is the only mechanism by which DNA is exchanged in nature and this is
false. The previous section has documented the discuvery of many genes
whose movement ois not explained by sexual recombination. Familiar sex
DOES NOT explain all gene movement in nature. Viruses, for example carry
genes between species eg


BACTERIAL GENE MOVING AMONG INSECTS

Virology 1995 Oct 1;212(2):673-85

Identification and preliminary characterization of a chitinase gene in
the Autographa californica

nuclear polyhedrosis virus genome.

Hawtin RE, Arnold K, Ayres MD, Zanotto PM, Howard SC, Gooday GW,
Chappell LH, Kitts PA, King LA,

Possee RD


A functional chitinase gene (chiA) has been identified in the genome of
the Autographa californica nuclear polyhedrosis virus

(AcMNPV). The predicted protein sequence of the AcMNPV chiA shares
extensive sequence similarity with chitinases

from bacteria and, in particular, the Serratia marcescens chitinase A
(60.5% identical residues). Phylogenetic analyses

indicate that AcMNPV, or an ancestral baculovirus, acquired the
chitinase gene from a bacterium via horizontal gene transfer.


see also GENES MOVE AROUND MANY MICROBES:

J Mol Microbiol Biotechnol 1999 Aug;1(1):45-50

Microbial gene transfer: an ecological perspective.

Paul JH

and

CROSS SPECIES GENE MOVEMENT IN INSECTS EXEMPLIFIED BY MOBILE GENES CALLED
TRANSPOSONS

Mol Biol Evol 1995 Sep;12(5):850-62

Recent horizontal transfer of a mariner transposable element among and
between Diptera and Neuroptera.

Robertson HM, Lampe DJ

cited above


37% of the human genome is composed of virus like foreign DNA. HIV is an
example of this kind of mobile DNA.


******************************

David Tribe Ph.D.

Senior Lecturer,

Department of Microbiology and Immunology

University of Melbourne

Parkville, Australia 3052

Fax 61 3 9347 1540

Ph. 61 3 8344 5703


*Please note my new email address for your records

detribe@unimelb.edu.au

(The old address works for the near future)





___________________________________________________________________________


Malcolm Livingstone


CSIRO Plant Industry Ph: (07) 3214 2902 Fax: (07) 3214 2288

120 Meiers Rd.

Indooroopilly

Qld 4068

AUSTRALIA


Email:Malcolm.Livingstone@tag.csiro.au