JP5702096B2 - Electrophoresis cassette, package thereof, and electrophoresis method - Google Patents

Description

  The present invention relates to a technique for analyzing a sample derived from a living body, and particularly to an electrophoresis cassette used for electrophoresis.

  In order to analyze biological samples, methods and devices for separating proteins and nucleic acids using differences in properties and analyzing and identifying the separated samples have been developed.

  As a separation method, gel electrophoresis, capillary electrophoresis, liquid chromatography and the like are known, and gel electrophoresis is widely used because of its simplicity and high resolution. In particular, as a gel electrophoresis for separating and analyzing proteins, SDS-polyacrylamide gel electrophoresis using an anionic surfactant sodium dodecyl sulfate (SDS) is widely used.

  As a technique for analyzing and identifying proteins separated by SDS-polyacrylamide gel electrophoresis, Western blotting is well known. The Western blotting method is a method for identifying a protein based on an antigen-antibody reaction using an antibody by adsorbing and fixing a separated protein in a gel to a transfer membrane.

  As described above, SDS-polyacrylamide gel electrophoresis and Western blotting are widely used in the biochemical field as analytical techniques excellent in terms of specificity and detection sensitivity as methods for analyzing proteins in samples. Yes.

  In addition, as a technique for shortening the time required for electrophoresis and transfer to a transfer film and easily proceeding with transfer, there is a method called a direct blotting method (Patent Document 1).

  In this method, when electrophoresis is performed, the transfer film is brought into direct contact with the gel end surface located downstream in the traveling direction of electrophoresis, and the electrophoresis is performed while moving the transfer film by power. Transfer can proceed simultaneously and automatically.

  Further, as a technique for expanding the application of the direct blotting method, a gel cassette for electrophoretic separation described in Patent Document 2 and a curved framed film described in Patent Document 3 are known. Patent Document 2 aims at improving the storage stability and simplifying the setting to the direct blotting device with respect to the electrophoresis part of the direct blotting device, that is, the parts composed of the sample inlet, gel, and sample outlet. The technology is described. Further, Patent Document 3 is a technique that focuses on the problem that transfer is not successful if the transfer film is wrinkled or bent when direct blotting is performed, and the transfer film is fixed to a frame. A technique for maintaining a stretched state is described.

US Pat. No. 5,234,559 Japanese translation of PCT Publication No. 9-501774 (published February 18, 1997) Japanese translation of PCT Publication No. 9-501239 (published February 5, 1997)

  However, when the direct blotting method is performed using the apparatus according to the prior art, the electrophoresis components (for example, those described in Patent Document 2) and the transfer film (for example, those described in Patent Document 2) that are separately stored for each experiment. It is necessary to prepare each of those described in Patent Document 3) and incorporate them into the main apparatus. At this time, depending on the accuracy of alignment (positioning) between the electrophoresis component and the transfer film, the reproducibility of the transfer result may be lowered.

  This invention is made | formed in view of said subject, and makes it the main objective to provide the instrument for implementing the direct blotting method more suitably.

  In order to solve the above problems, an electrophoresis cassette according to the present invention is an electrophoresis cassette for storing a separation medium for separating a sample in a specific direction by electrophoresis. A transfer film for transferring a sample, and a transfer film guide for holding the transfer film and defining a path of movement of the transfer film so as to slide with respect to an end face of the separation medium in the specific direction It is characterized by having.

  According to the above configuration, since the electrophoresis cassette and the transfer film are integrated with the transfer film slidable with respect to the end surface of the separation medium located downstream in the traveling direction of the electrophoresis, The direct blotting method can be performed, and the user does not need to manually combine the electrophoresis cassette and the transfer membrane, and can easily prepare an experiment using the direct blotting method. It is possible to easily prevent a decrease in the reproducibility of the experimental result due to the positional deviation between the electrophoresis cassette and the transfer film. In addition, since the electrophoresis cassette and the transfer film are integrated, it can be stored in a compact manner.

  In the electrophoresis cassette according to the present invention, the transfer film is preferably a hydrophobic PVDF film or a nitrocellulose film.

  According to said structure, a transfer film can adsorb | suck suitably the sample isolate | separated in the separation medium, especially samples, such as protein derived from a biological body, and can perform transcription | transfer successfully.

  In the electrophoresis cassette according to the present invention, it is preferable that the transfer film guide has a slit structure in sliding contact with the transfer film.

  According to the above configuration, the transfer film is subjected to frictional force from the slit structure, so that bending, wrinkles, and the like are extended. Thereby, the transfer of the sample to the transfer film can be performed without unevenness.

  The electrophoresis cassette according to the present invention preferably has a curved surface portion, and the path of movement of the transfer film defined by the transfer film guide preferably includes a portion that slides on the curved surface. .

  According to said structure, when a transfer film slides on a curved surface part, a curved surface part works like a roller and a bending, a wrinkle, etc. are extended. Thereby, the transfer of the sample to the transfer film can be performed without unevenness.

  The electrophoresis cassette package according to the present invention is characterized in that the electrophoresis cassette according to the present invention is sealed together with a liquid.

  According to the above configuration, the separation medium can be moisturized and deterioration of the separation medium can be suppressed.

  In general, when a transfer film is used, it must be treated with a buffer solution before use. Specifically, it is necessary to wet the dried transfer film once with ethanol or methanol, and then immerse it in a buffer solution for 10 to 30 minutes.

  On the other hand, according to the above configuration, by sealing the transfer film in a state wetted with a liquid in advance, the user does not need to wet the transfer film every use, and the direct blotting method is more easily performed. be able to.

  In the electrophoresis cassette package according to the present invention, the liquid is preferably pure water or an electrophoresis buffer.

  According to said structure, the cassette for electrophoresis can be preserve | saved in the state by which the transfer film was pre-processed suitably.

  The electrophoresis method according to the present invention includes a step of taking out the electrophoresis cassette from a package of the electrophoresis cassette according to the present invention, and a step of performing a direct blotting method using the electrophoresis cassette. You may do it.

  According to the above method, the pretreatment step can be omitted when the direct blotting method is performed.

  According to the electrophoresis cassette of the present invention, the user does not need to manually combine the electrophoresis cassette and the transfer film, and can easily prepare an experiment using the direct blotting method. It is possible to easily prevent a decrease in the reproducibility of the experimental result due to the positional deviation between the electrophoresis cassette and the transfer film.

It is a figure which shows schematic structure of the separation chip | tip incorporated in the cassette for electrophoresis which concerns on one Embodiment of this invention, (a) shows the disassembled perspective view of a separation chip, (b) shows the perspective view of a separation chip. . It is a perspective view which shows schematic structure of the housing | casing of the cassette for electrophoresis which concerns on one Embodiment of this invention. It is a figure which shows the variation of the shape of the transfer film guide 121 with which the cassette for electrophoresis which concerns on one Embodiment of this invention is provided. 1A and 1B are diagrams for explaining a schematic structure of an electrophoresis cassette according to an embodiment of the present invention, in which FIG. 1A is a perspective view of a combination of a housing and a separation chip, and FIG. 2 is a cross-sectional view of a combination of a body and a separation chip, (c) is a perspective view of a transfer film, and (d) is a cross-section of an electrophoresis cassette in which a housing, a separation chip, and a transfer film are combined. The figure is shown. It is a figure for demonstrating the schematic structure of the cassette for electrophoresis which concerns on one Embodiment of this invention, (a) shows the perspective view of the separation chip and housing | casing which comprise the cassette for electrophoresis, (b) These show sectional drawing of the cassette for electrophoresis. It is sectional drawing which shows schematic structure of the package with which the cassette for electrophoresis which concerns on one Embodiment of this invention was sealed. 1 is a cross-sectional view of an electrophoresis apparatus that performs a direct blotting method in which an electrophoresis cassette according to an embodiment of the present invention is incorporated. It is sectional drawing which shows schematic structure of the package with which the inside of the electrophoresis element in which the cassette for electrophoresis which concerns on one Embodiment of this invention was integrated was sealed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic structure of a separation chip 110 incorporated in an electrophoresis cassette 100 according to an embodiment of the present invention. FIG. 1A shows an exploded perspective view of the separation chip 110, and FIG. 1B shows a perspective view of the separation chip 110.

  The separation chip 110 is configured by overlapping a lid member 111 and a base 112. Spacers 115 are provided at both ends of the base 112, and a space is formed between the lid member 111 and the base 112 in a state where the cover member 111 and the base 112 are overlapped, and the separation medium 117 is formed in this space. Filled. The separation chip 110 is provided with openings 116 and 118 through which the separation medium 117 is exposed.

  As the separation medium 117, for example, polyacrylamide gel used for protein electrophoresis can be used. However, the separation medium 117 is not limited thereto, and an agarose gel having a molecular sieving effect may be used, or an ultrafine column called a nanopillar. The structure which stands in the said space may be sufficient.

  By using the lid member 111, deformation, drying, etc. of the separation medium 117 can be prevented. Further, by forming the sample introduction port 113 in the lid member 111, the sample can be easily introduced into the separation medium 117. The sample introduction port 113 is preferably provided on the side opposite to the side where the opening 116 is provided.

  As a material of the lid member 111 and the base 112, for example, glass having a hydrophilic surface can be suitably used, but is not limited thereto, and is not limited thereto, but is not limited to acrylic resin, polycarbonate resin, polystyrene resin, PET resin, polyvinyl chloride resin, An insulating material such as ceramic can be used.

  Further, when the separation medium 117 is formed, a sample introduction port lid 114 that closes the sample introduction port 113 may be used. For example, an acrylic resin that can be easily processed can be suitably used as a material for the sample inlet lid 114, but is not limited thereto, and is not limited thereto. Acrylic resin, polycarbonate resin, polystyrene resin, PET resin, vinyl chloride resin, ceramic An insulating material such as can be used.

  FIG. 2 is a perspective view showing a schematic structure of the housing 120 of the electrophoresis cassette 100. The housing 120 functions as a buffer solution tank that houses the separation chip 110 and further stores a buffer solution, and has an opening 122 at the top and an opening 123 at the bottom of the side.

  The casing 120 is also provided with transfer film guides 121a and 121b for holding the transfer film 130 and defining the movement path of the transfer film 130. The number of transfer film guides is not limited to two, and may be one or three or more.

  FIG. 3 is a diagram showing variations in the shape of the transfer film guide 121a. FIG. 3 shows a state where the electrophoresis cassette 100 is observed from the direction of the black arrow in FIG.

  As shown in FIG. 3A, the transfer film guide 121a may have a slit structure having a width equal to or greater than the width of the transfer film 130.

  As shown in FIG. 3B, the transfer film guide 121a may have a claw structure for holding both ends of the transfer film 130. As shown in FIG. 3C, the transfer film guide 121a may have an upward claw structure for gripping both ends of the transfer film 130.

  Further, as shown in FIG. 3D, the transfer film guide 121a has a slit structure having a width equal to or larger than the width of the transfer film 130, and friction is generated when the transfer film 130 passes through the slit structure. You may have a slit structure which has the gap of the grade which arises. In the slit structure shown in FIG. 3D, the transfer film guide 121a is able to extend wrinkles and slackness of the transfer film 130 by slidingly contacting the transfer film 130 and applying a frictional force to the transfer film 130. .

  Further, as shown in FIG. 3E, the transfer film guide 121a may include a roller α provided so as to be in sliding contact with the transfer film 130. In this case, as in the case shown in FIG. 3D, the roller α applies a frictional force to the transfer film 130, so that wrinkles and slack can be extended. In addition, since the transfer of the transfer film 130 can be made smooth by the rotation of the roller α, it is possible to prevent the transfer film 130 from being broken due to excessive frictional force.

  The shape of the transfer film guide 121b can be the same as that of the transfer film guide 121a. The shapes of the transfer film guides 121a and 121b may be the same or different from each other. Further, the width along the traveling direction of the transfer film 130 in the transfer film guides 121a and 121b is not particularly limited.

  As a material of the housing 120, for example, an acrylic resin that can be easily processed can be suitably used. However, the material is not limited to this, and a polycarbonate resin, a polystyrene resin, a PET resin, a vinyl chloride resin, a metal, a carbon material, or the like is used. be able to.

  FIG. 4 is a diagram for explaining a schematic structure of the electrophoresis cassette 100. 4A shows a perspective view of a combination of the case 120 and the separation chip 110, and FIG. 4B shows a cross-sectional view of a combination of the case 120 and the separation chip 110. 4C is a perspective view of the transfer film 130, and FIG. 4D is a cross-sectional view of the electrophoresis cassette 100 in which the casing 120, the separation chip 110, and the transfer film 130 are combined. In addition, the cut surface in FIG.4 (b) and (d) follows a dotted line in Fig.4 (a).

  As shown in FIGS. 4A and 4B, the separation chip 110 is housed in the housing 120. At this time, the separation chip 110 is disposed so that the opening 116 of the separation chip 110 is exposed to the outside from the opening 123 of the housing 120. As a result, the separation medium 117 is exposed to the outside from the opening 123 of the housing 120. Thereby, the transfer film 130 can be moved (slid) while being brought into contact with the end surface of the separation medium 117.

  Note that the opening 123 of the housing 120 is preferably closed by the separation chip 110. Thereby, as will be described later, the housing 120 can be suitably used as a buffer solution tank on the cathode side.

  As shown in FIG. 4 (c), the transfer film 130 has a sheet shape, and is a PVDF film (polyvinylidene fluoride film) which is a known transfer film for protein blotting, or a hydrophobic film, Nitrocellulose membranes, nylon membranes, and the like that have a high binding force to proteins can be used, but are not limited to these, and any membrane that can adsorb a target sample can be suitably used.

  As shown in FIG. 4D, the transfer film 130 is inserted into the transfer film guides 121a and 121b and integrated with the electrophoresis cassette 100. When the direct blotting method is performed, the transfer film 130 moves (slids) in contact with the end surface of the separation medium 117 in the direction of the arrow in the figure, thereby separating the transfer film 130 on the separation medium 117. The biological sample is transferred. The transfer film 130 can be moved, for example, by pulling the end 131 of the transfer film 130.

  At this time, it is important for the transfer film 130 to move so as not to move from side to side. If the transfer film 130 is bent and moved, the transfer image of the biological sample on the transfer film 130 is affected, a bent image is formed, and the reproducibility of the result is deteriorated.

  Further, in order to prevent the transfer image from being deformed, it is desirable that the transfer film 130 does not bend and wrinkle when the transfer film 130 moves. FIG. 5 is a diagram for explaining a schematic structure of an electrophoresis cassette 100 ′ according to a modified example for further suppressing the occurrence of bending and wrinkling. FIG. 5A shows a perspective view of the separation chip 110 and the housing 120 that constitute the electrophoresis cassette 100 ′, and FIG. 5B shows a cross-sectional view of the electrophoresis cassette 100 ′.

  5A and 5B, the casing 120 ′ of the electrophoresis cassette 100 ′ further includes a transfer film guide 121c with respect to the casing 120, and the transfer film guide 121a and the transfer film A curved surface portion 124 is provided between the guide 121c and the guide 121c. By adopting such a configuration, the transfer film 130 slides on the curved surface portion 124. As a result, it is possible to obtain an effect that the transfer film 130 having bending, wrinkles, or the like is stretched by a roller, and it is possible to correct the bending and wrinkling of the transfer film 130 during direct blotting.

  Next, specifications for storing the electrophoresis cassette 100 in a stable state will be described. FIG. 6 is a cross-sectional view showing a schematic structure of the package 150 in which the electrophoresis cassette 100 is sealed. As shown in FIG. 6, the package 150 is configured by vacuum-packing the electrophoresis cassette 100 into a bag 140 containing pure water 141.

  When the electrophoresis cassette 100 is stored, it is the separation medium 117 such as polyacrylamide in the separation chip 110 that is most rapidly deteriorated. Polyacrylamide and the like can be deteriorated by drying, high heat, oxygen in the air, light, physical impact, and the like.

  In order to protect the separation medium 117 from such deterioration factors, in order to keep the inside of the package 150 at a high humidity, the pure water 141 is sealed and the air is removed in order to prevent exposure to oxygen. It is effective to do. Further, in order to prevent damage from light, particularly ultraviolet rays, it is desirable to use a bag 140 made of a light-shielding material, to become hot, and to store at a low temperature of 4 ° C. to prevent temperature change.

  By storing as described above, the electrophoresis cassette 100 can be stored in a stable state for a long period of time.

  Furthermore, by sealing the electrophoresis cassette 100 with the bag 140 in which the pure water 141 is sealed, the pretreatment process of the transfer film 130 that the experimenter must normally perform before the experiment can be omitted.

  When the package 150 is not used, the transfer film 130 needs to be pretreated to be wet with pure water, an anode buffer (buffer solution) or the like before the experiment. For example, when a PVDF film is used as the transfer film 130, since the PVDF film is hydrophobic, it cannot be wetted with an anode buffer in a dry state (the surface of the transfer film 130 repels liquid and the transfer film 130 is repelled). The liquid does not soak inside.) Therefore, it is necessary to immerse the transfer film 130 in methanol or ethanol, wet the surface of the transfer film 130, and then immerse it in pure water or an anode buffer.

  This pretreatment of the transfer film 130 is an important step for promoting normal direct blotting. If the pretreatment is insufficient, or if the elapsed time after the pretreatment is long and the transfer film 130 is dried, a portion that is not wet may occur. If there is a portion that is not wet on the transfer film 130 at the time of transfer, the transfer at that portion is inhibited. Therefore, it is preferable that the transfer film 130 is uniformly wet. In order to make the degree of wetting in the transfer film 130 uniform, pretreatment is performed by immersing in pure water or an anode buffer for as long a time as possible. It is preferable to start blotting.

  On the other hand, by using the package 150, the electrophoresis cassette 100 that is immersed in pure water or an anode buffer and stored in a state where the entire surface of the transfer film 130 is uniformly wet until immediately before setting in the apparatus is used. Can do. When the electrophoresis cassette 100 is removed from the package 150, the transfer film 130 is sufficiently pre-processed and can be used as it is for the experiment.

  The liquid sealed in the bag 140 may be other than pure water, for example, a buffer solution for electrophoresis.

  Finally, implementation of the direct blotting method using the package 150 will be described. FIG. 7 shows a cross-sectional view of the electrophoresis apparatus 10 that implements the direct blotting method in which the electrophoresis cassette 100 is incorporated.

(Incorporation of the electrophoresis cassette 100 into the electrophoresis apparatus 10)
First, the electrophoresis cassette 100 is taken out from the package 150 and set in the electrophoresis apparatus 10. The electrophoresis apparatus 10 is made of a non-conductive material that can be easily processed, such as an acrylic material.

  Conventionally, the separation chip 110 including the separation medium 117 and the transfer film 130 had to be set separately in the electrophoresis apparatus 10, but if the transfer film integrated type electrophoresis cassette 100 of the present invention is used, It only needs to be done once.

  The operation of slidingly contacting the transfer film 130 and the separation chip 110 requires the most careful operation in the process of performing the direct blotting method. For example, a minute foreign matter is present on the adhesive surface between the transfer film 130 and the separation chip 110. When bubbles or the like are mixed, a gap may be generated between the transfer film 130 and the end face of the separation medium 117. The occurrence of a gap on the adhesive surface is fatal in the direct blotting method, and the protein discharged from the separation chip 110 diffuses before being transferred to the transfer film 130 and is transferred in a blurred form, or Problems such as not being transferred occur.

  As described above, the separation chip 110 and the transfer film 130 need to be strictly adhered manually by the experimenter for each experiment, and it is less likely to cause problems if they are integrated in advance as in the present invention. . The same applies to the case where the transfer film 130 and the separation chip 110 are not bonded and combined by other methods.

  Subsequently, the end 131 of the transfer film 130 is attached to the transfer arm 14 for the transfer film. The moving arm 14 is preferably one that mechanically moves the transfer film 130 at a pre-programmed moving speed.

(Buffer injection)
A cathode buffer is injected into the buffer solution tank 15 in the electrophoresis cassette 100 with the opening 118 opened, and an anode buffer is injected into the buffer solution tank 16 in the casing 11 of the electrophoresis apparatus 10 with the opening 116 opened. To do. As the cathode buffer and the anode buffer, any buffer having conductivity can be used. Examples of buffers that can be used for electrophoresis include Tris / glycine buffer, acetate buffer, and sodium carbonate buffer. , CAPS buffer solution, Tris / boric acid / EDTA buffer solution, Tris / acetic acid / EDTA buffer solution, MOPS, phosphate buffer solution, Tris / Tricine buffer solution and the like can be used.

(Place electrode)
The negative electrode 12 is disposed in the buffer solution tank 15, and the positive electrode 13 is disposed in the buffer solution tank 16. The negative electrode 12 and the positive electrode 13 are made of a conductive material such as metal. As a material for forming the negative electrode 12 and the positive electrode 13, for example, platinum is preferable from the viewpoint of suppressing ionization of the electrode.

(Sample introduction)
Subsequently, the sample introduction port lid 114 of the separation chip 110 is opened, and a sample that has been subjected to pretreatment such as purification and SDS treatment is introduced from the sample introduction port 113. The sample can be introduced by quantifying the liquid with a Pipetman. In addition, when performing two-dimensional electrophoresis, the IPG gel after performing isoelectric focusing may be inserted into the sample inlet 113 and introduced.

  The term “sample” or “sample” is used interchangeably with specimens, preparations in the art, and as used herein, a “biological sample” or equivalent thereof is intended. A “biological sample” is intended to be any preparation obtained from biological material as a source (eg, an individual, body fluid, cell line, tissue culture or tissue section). Biological samples include body fluids (eg, blood, saliva, plaque, serum, plasma, urine, synovial fluid, and fluids) and tissue sources. A preferred biological sample is a subject sample. Preferred subject samples are skin lesions, sputum, pharyngeal mucus, nasal mucus, pus, or secretions obtained from the subject.

  As used herein, the term “tissue sample” intends a biological sample obtained from a tissue source. Methods for obtaining tissue biopsies and body fluids from mammals are well known in the art. As used herein, the term “sample” includes, in addition to the biological sample and the tissue sample, a protein sample, genomic DNA sample and / or extracted from the biological sample and the tissue sample. A total RNA sample is also included.

  In general, the sample is used after being purified and adjusted after being taken out of the living body. For example, when a protein sample is subjected to polyacrylamide electrophoresis, it is necessary to react the protein sample with SDS before electrophoresis.

(Electrophoresis)
After the sample is introduced, electrophoresis starts by passing a current between the negative electrode 12 and the positive electrode 13. At this time, by moving the moving arm 14 at a preprogrammed speed, the transfer film 130 can be moved while the transfer film 130 is in direct sliding contact with the sample discharge surface of the separation chip 110 (end surface of the separation medium 117). it can. Thereby, in the separation medium 117, the sample can be separated in a specific direction (direction from the opening 118 toward the opening 116), and the separated sample can be sequentially transferred to different parts of the transfer film 130.

  It is also possible to package and store the entire electrophoresis apparatus 10 with the electrophoresis cassette 100 incorporated therein. FIG. 8 is a cross-sectional view showing a schematic structure of a package 30 in which the electrophoresis apparatus 10 incorporating the electrophoresis cassette 100 is sealed with a bag 20 and can be stored. By storing in the state as shown in FIG. 8, the experimenter can omit the work of incorporating the electrophoresis cassette 100 into the electrophoresis apparatus 10 before the experiment. That is, the experimenter can prepare the electrophoresis apparatus 10 incorporating the electrophoresis cassette 100 simply by taking out the electrophoresis apparatus 10 from the package 30. Note that the package 30 may be packaged in a liquid-containing state, similar to the package 150.

  The present invention can be used in the field of analysis of biological samples, chemical samples, and the like and the manufacture of analytical instruments therefor.

DESCRIPTION OF SYMBOLS 10 Electrophoresis apparatus 11 Case 12 Negative electrode 13 Positive electrode 14 Moving arm 15, 16 Buffer solution tank 20, 140 Bag 30, 150 Package 100, 100 'Electrophoresis cassette 110 Separation chip 113 Sample inlet 116 Opening 117 Separation medium 120, 120 ′ casing 121a, 121b, 121c transfer film guide 122, 123 opening 130 transfer film 141 pure water

Claims (9)

An electrophoresis cassette for storing a separation medium for separating a sample in a specific direction by electrophoresis,
A transfer film for transferring the separated sample;
A transfer film guide that holds the transfer film and defines a movement path of the transfer film so as to slide with respect to an end face of the separation medium in the specific direction;
The transfer film guide is configured to insert the transfer film, and is provided so as to surround both side ends of the inserted transfer film .
The transfer film guide is provided on a bottom surface of the electrophoresis cassette and on a surface of the electrophoresis cassette that faces away from the end surface in the specific direction of the separation medium. A cassette for electrophoresis.   2. The electrophoresis cassette according to claim 1, wherein the transfer film is a hydrophobic PVDF film or a nitrocellulose film.   The electrophoresis cassette according to claim 1 or 2, wherein the transfer film guide has a slit structure in sliding contact with the transfer film.   The electrophoresis cassette according to claim 1, wherein the transfer film guide has a roller structure in sliding contact with the transfer film. Has a curved surface,
5. The electrophoresis according to claim 1, wherein a path of movement of the transfer film defined by the transfer film guide includes a portion that slides on the curved surface portion. 6. Cassette.   6. An electrophoresis cassette package, wherein the electrophoresis cassette according to claim 1 is hermetically sealed.   7. The electrophoresis cassette package according to claim 6, wherein the electrophoresis cassette is sealed together with a liquid.   8. The electrophoresis cassette package according to claim 7, wherein the liquid is pure water or an electrophoresis buffer. Removing the electrophoresis cassette from the electrophoresis cassette package according to any one of claims 6 to 8,
And a step of performing a direct blotting method using the above-described electrophoresis cassette.

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