Biology Reference
In-Depth Information
9.15 TE Vectors to Transform Insects other than
Drosophila
The genetic modification of pest and beneficial insects by recombinant DNA meth-
ods to reduce their pest status or to improve their beneficial effects, respectively,
is a goal of many scientists (see Chapter 14,
Ashburner et al. 1998
,
Fraser 2012
).
A mechanism with which to reliably insert exogenous DNA into the genome of
the target insect and to have it transmitted in a stable manner in the germ line
is required to achieve such goals. The
P
-element model dominated the efforts of
many scientists initially, but other TE-insertion vectors were developed from
piggy-
Bac
,
mariner
,
Hermes
,
Minos
, and
hobo
.
Palazzoli et al. (2010)
discuss the scientific
and legal issues surrounding the patenting of these transposon tools.
9.15.1
piggyBac
piggyBac
is a class II TE found in many insect and other eukaryotic genomes
(
Fraser 2000
). The
piggyBac
vector can transpose in a
Spodoptera frugiperda
cell line (
Fraser et al. 1995, Elick et al. 1996
), as well as in embryos of
D. mela-
nogaster
,
Aedes aegypti
, and
Trichoplusia ni
(
Lobo et al. 1999
). The
piggyBac
vector has transformed agricultural pests such as
Ceratitis capitata
(
Handler
et al. 1998
), and
Pectinophora gossypiella
(
Peloquin et al. 2000
). It can transform
Bombyx mori
(
Tamura et al. 2000
). Thus,
piggyBac
appears to have a broad host
range, has a transformation rate averaging 2-5%, and the insertions appear
to be precise (producing a characteristic TTAA duplication at the insertion site)
and stable, suggesting that this vector is useful for transforming diverse insects
(
Fraser 2000, Handler 2002
). It does not, however, function in all insects, perhaps
due to repression by endogenous elements (
Fraser 2012
).
9.15.2
Hermes
and
Herves
The
Hermes
TE was discovered in the house fly
Musca domestica
(
O'Brochta
et al. 1996
).
Hermes
transposed in embryos of
Aedes aegypti
(
Sarkar et al.
1997b
).
Hermes
is functional in several dipteran families (Drosophilidae,
Calliphoridae, Tephritidae, and Muscidae) (
Atkinson and O'Brochta 2000,
O'Brochta et al. 2000
). Interestingly, the two strains of
M. domestica
tested
exhibited the lowest rates of transformation (
Sarkar et al. 1997a
), perhaps
because
Hermes
is present in them and some form of resistance to
Hermes
has
been selected for. Likewise, the
Lucilia cuprina
strain tested exhibited low levels
of transposition, perhaps because a
Hermes
-like element called
hermit
is present
in the genome that elicited a partial resistance.
Aedes aegypti
(
Jasinskiene et al. 1998, 2000
) was transformed with
Hermes
,
but integrations did not occur precisely at the end of the terminal inverted
