2. Method for Producing Euglena of the Present Invention
The method for producing a Euglena of the present
invention is a method for producing a Euglena carrying a ยีนดีดี and a ยีนจากภายนอกที่สนใจ in an expressible
manner, the method comprising the step of:
(1) introducing the ยีนดีดีและยีนจากภายนอก of
interest into a Euglena by the อะโกรแบคทีเรียม method.
[0033]
The drug resistance gene, the ยีนจากภายนอกที่สนใจ,
and the Euglena are as explained in Section 1 above. [0034]
The อะโกรแบคทีเรียม method was originally used as a
การทรานสฟอร์ม method for plants. The อะโกรแบคทีเรียม method uses อะโกรแบคทีเรียม tumefaciens (hereafter, "อะโกรแบคทีเรียม"), a gram-
negative soil bacterium that causes tumors called crown gall in
plants. A gene region called transferred-DNA (T-DNA), which is a portion of a large พลาสมิด called tumor-inducing (Ti) พลาสมิด
possessed by อะโกรแบคทีเรียม, is removed, enters plant cells
through a type-IV secretion system, and is introduced into the
nuclear genome by homologous recombination, leading to tumor
formation. The removal of T-DNA requires a group of genes called the virulence (vir) region. Although the sequences of both
บริเวณ are present on the Ti พลาสมิด, these บริเวณ are known to function together even if they are not on the same พลาสมิด.
[0035]
The อะโกรแบคทีเรียม method is preferably a ไบนารี เวคเตอร์
method. The ไบนารี เวคเตอร์ method, which was developed utilizing
the properties of อะโกรแบคทีเรียม described above, uses two
different พลาสมิดs. In the ไบนารี เวคเตอร์ method, the vir region
and the T-DNA region, which are inherently on the same พลาสมิด,
are carried on different พลาสมิดs, and these พลาสมิดs are
10 simultaneously used. More specifically, อะโกรแบคทีเรียม carrying
both a พลาสมิด containing only the vir region (helper พลาสมิด)
and a พลาสมิด containing only the T-DNA region (ไบนารี เวคเตอร์) is
used. The process is as follows. First, a gene to be introduced
into an organism used as a host is inserted into the T-DNA region 15 on a ไบนารี เวคเตอร์, and this พลาสมิด is introduced into
อะโกรแบคทีเรียม carrying a helper พลาสมิด. The thus-obtained
อะโกรแบคทีเรียม carrying the two types of พลาสมิดs is co-cultured
with the host organism, thereby introducing the desired gene into
the host. The co-culturing method for อะโกรแบคทีเรียม infection may 20 be either a method using a solid medium or a method using a
liquid medium. A method using a liquid medium is more preferable.
Additionally, in co-culturing, it is desirable to add a phenol
compound as an อะโกรแบคทีเรียม infection induction substance. The
phenol compound used as an infection induction substance is most
desirably acetosyringone.
[0036]
The method for producing a Euglena of the present
invention may further comprises the step of:
(2) culturing the Euglena obtained in step (1) in the presence of
the drug to which the introduced ยีนดีดี shows
resistance. [0037]
สภาวะ for the culture are not particularly limited.
When ซีโอซิน or ไฮโกรไมซิน is used as the drug, the culture is
preferably performed at a pH of 6 to 8. When 6418 is used as the
drug, the culture is preferably performed at a pH of 5 to 8.
Although a pH near 5.0 is generally considered to be advantageous
to the growth of Euglena, performing the culture under the above
สภาวะ is advantageous since these drugs are more stably
5 maintained, and a Euglena carrying a drug resistance gene and a
ยีนจากภายนอกที่สนใจ in an expressible manner is more efficiently obtained.
When a drug that is stable to acids and bases is used
as the drug, the culture สภาวะ can be set without being
particularly affected by pH สภาวะ.
[0039]
There is no particular limitation on the culture
สภาวะ in step (2) . Examples include the following สภาวะ.
For example, the culture is performed in a KH selective plate
medium. The concentration of the drug in the medium is not
particularly limited. When a ซีโอซิน resistance gene is introduced,
ซีโอซิน is used in an amount of, for example, 20 to 100 µg/ml. If
necessary, one or more other drugs may be further added to the
medium. There is no particular limitation, and when a ซีโอซิน
resistance gene is introduced, for example, ซีโฟแทกซีม may be
further added to the medium in an amount of 50 to 200 jig/mi. This
prevents อะโกรแบคทีเรียม alone from forming colonies after the
establishment of infection, and is thus advantageous.
[0040]
When a ไฮโกรไมซิน resistance gene is introduced,
ไฮโกรไมซิน is used in an amount of, for example, 5 to 100 jig/ml. Further, ซีโฟแทกซีม may be added to the medium in an amount of 50 to 200 jig/mi. This prevents อะโกรแบคทีเรียม alone from forming
colonies after the establishment of infection, and is thus
advantageous.
[0041]
When a G418 resistance gene is introduced, G418 is used
in an amount of, for example, 5 to 100 jig/ml. Further, ซีโฟแทกซีม
may be added to the medium in an amount of 50 to 200 jig/mi. This
prevents อะโกรแบคทีเรียม alone from forming colonies after the establishment of infection, and is thus advantageous.
[0042]
The number of cells at the start of culture is not
particularly limited and is, for example, lx104 to 1x108 cells.
[0043]
The culture period is not particularly limited, and is,
for example, 2 to 7 days.
[0044]
Step (2) may be performed only once or, if necessary,
may be performed two or more times.
When the step is performed two or more times, the
number of cells at the start of culture is not particularly
limited, but may be reduced in a stepwise manner if necessary. 15 Although there is no particular limitation, the number of cells
at the start of culture may be reduced to about one-fifth to
about one-half of that of the previous stage.