Transfer to the Indigenous Community
The capability to measure transformation of DNA in natural
microbial communities has challenged investigators for
years. Nearly all such attempts have used closed
microcosms. However, the work of Day and Fry (Williams
et al., 1992; Williams et al., 1996) is unique in that an
indigenous mercury resistance plasmid (pQM17) was used
in the river from which it was isolated in open filter matings.
Stones with filters containing the donors or DNA were
placed next to stones containing recipients. Transfer
occurred with frequencies ranging from 10-6 to 10-4 per
recipient. A significant effect of temperature was observed,
with no transfer below 10 °C.
Natural transformation of indigenous marine bacteria
has been demonstrated by Frischer et al. (1994) using
plasmid multimers of pQSR50. Plasmid multimers were
used to ensure internal homology and thus provide a site
for self-homologous recombination. The ambient microbial
communities in water column samples (20 L) or coral
mucus (1 L) were first concentrated to approx. 50 ml and 1
ml used in filter transformation assays. For sediments and
bacteria in sponge tissue, the bacteria were extracted
mechanically and then used in filter transformation assays.
Transformation was assessed as expression of the
antibiotic resistance genes encoded by the plasmid in
combination with confirmation by molecular probing.
However, certain environments contained indigenous
marine bacteria that possessed sequences that hybridized
with the probe used and any such environments were not
considered further. Positive transformation was found in 5
of 13 experiments, with transfer frequencies ranging from
3.6x10-6 to 1.13x10-9. In all cases of plasmid transfer to
the natural community, restriction profiles from
transformants were altered when compared to the parent
plasmid. Differences in the recovered transformant
plasmids were accounted for by difference in methylation
compared to the parent plasmid, as well as some genetic
rearrangement (Williams et al., 1997). Thus, transfer to
the indigenous flora, at least when considering plasmid
DNA, can result in rearrangement and alteration of the
DNA, contributing to plasmid and recipient evolution.
Transfer to the Indigenous Community
The capability to measure transformation of DNA in natural
microbial communities has challenged investigators for
years. Nearly all such attempts have used closed
microcosms. However, the work of Day and Fry (Williams
et al., 1992; Williams et al., 1996) is unique in that an
indigenous mercury resistance plasmid (pQM17) was used
in the river from which it was isolated in open filter matings.
Stones with filters containing the donors or DNA were
placed next to stones containing recipients. Transfer
occurred with frequencies ranging from 10-6 to 10-4 per
recipient. A significant effect of temperature was observed,
with no transfer below 10 °C.
Natural transformation of indigenous marine bacteria
has been demonstrated by Frischer et al. (1994) using
plasmid multimers of pQSR50. Plasmid multimers were
used to ensure internal homology and thus provide a site
for self-homologous recombination. The ambient microbial
communities in water column samples (20 L) or coral
mucus (1 L) were first concentrated to approx. 50 ml and 1
ml used in filter transformation assays. For sediments and
bacteria in sponge tissue, the bacteria were extracted
mechanically and then used in filter transformation assays.
Transformation was assessed as expression of the
antibiotic resistance genes encoded by the plasmid in
combination with confirmation by molecular probing.
However, certain environments contained indigenous
marine bacteria that possessed sequences that hybridized
with the probe used and any such environments were not
considered further. Positive transformation was found in 5
of 13 experiments, with transfer frequencies ranging from
3.6x10-6 to 1.13x10-9. In all cases of plasmid transfer to
the natural community, restriction profiles from
transformants were altered when compared to the parent
plasmid. Differences in the recovered transformant
plasmids were accounted for by difference in methylation
compared to the parent plasmid, as well as some genetic
rearrangement (Williams et al., 1997). Thus, transfer to
the indigenous flora, at least when considering plasmid
DNA, can result in rearrangement and alteration of the
DNA, contributing to plasmid and recipient evolution.
การแปล กรุณารอสักครู่..
Transfer to the Indigenous Community
The capability to measure transformation of DNA in natural
microbial communities has challenged investigators for
years. Nearly all such attempts have used closed
microcosms. However, the work of Day and Fry (Williams
et al., 1992; Williams et al., 1996) is unique in that an
indigenous mercury resistance plasmid (pQM17) was used
in the river from which it was isolated in open filter matings.
Stones with filters containing the donors or DNA were
placed next to stones containing recipients. Transfer
occurred with frequencies ranging from 10-6 to 10-4 per
recipient. A significant effect of temperature was observed,
with no transfer below 10 °C.
Natural transformation of indigenous marine bacteria
has been demonstrated by Frischer et al. (1994) using
plasmid multimers of pQSR50. Plasmid multimers were
used to ensure internal homology and thus provide a site
for self-homologous recombination. The ambient microbial
communities in water column samples (20 L) or coral
mucus (1 L) were first concentrated to approx. 50 ml and 1
ml used in filter transformation assays. For sediments and
bacteria in sponge tissue, the bacteria were extracted
mechanically and then used in filter transformation assays.
Transformation was assessed as expression of the
antibiotic resistance genes encoded by the plasmid in
combination with confirmation by molecular probing.
However, certain environments contained indigenous
marine bacteria that possessed sequences that hybridized
with the probe used and any such environments were not
considered further. Positive transformation was found in 5
of 13 experiments, with transfer frequencies ranging from
3.6x10-6 to 1.13x10-9. In all cases of plasmid transfer to
the natural community, restriction profiles from
transformants were altered when compared to the parent
plasmid. Differences in the recovered transformant
plasmids were accounted for by difference in methylation
compared to the parent plasmid, as well as some genetic
rearrangement (Williams et al., 1997). Thus, transfer to
the indigenous flora, at least when considering plasmid
DNA, can result in rearrangement and alteration of the
DNA, contributing to plasmid and recipient evolution.
การแปล กรุณารอสักครู่..