Expanding cam lock for sealing slab gels in an electrophoresis apparatus

Abstract

An expanding cam lock for use with an electrophoresis system is disclosed herein. The cam lock allows the simultaneous use of multiple slab gel cassettes in first and second buffer core assemblies in an electrophoresis system while maintaining the necessary compressive force to create a liquid-tight seal between the anode and cathode buffer solutions. In one example embodiment, the expanding earn lock includes a base plate with a first surface adapted to engage the first buffer core assembly and a follower plate having second surface adapted to engage the second buffer core assembly, buffer dam or buffer displacement dam. The base plate and the follower plate are slidably coupled together and are designed for insertion between the first buffer core assembly and the second buffer core assembly, buffer dam or buffer displacement dam in the electrophoresis container. A cam is positioned between and moveably coupled with the base plate and the follower plate. The cam is movable from a first position to a second position to urge the first and second surfaces to secure the gel cassette to the first and second buffer core assemblies. Also provided herein is a buffer displacement dam. Also provided herein are kits and assemblies which incorporate the expanding cam and buffer displacement dam described herein.

What is claimed is: 
     
         1 . An expanding cam lock for sealing at least one gel cassette in an electrophoresis apparatus, the expanding cam lock comprising:
 a base plate having a first surface adapted to engage a buffer core assembly comprising at least one electrophoresis gel cassette;   a follower plate having a second surface adapted to engage a partition assembly, and   a cam positioned between and moveably coupled with the base plate and the follower plate;   
       wherein, the base plate and the follower plate are slideably coupled together and configured for insertion between the buffer core assembly and the partition assembly in the electrophoresis apparatus, and the cam being movable from a first position to a second position to urge the first surface toward the electrophoresis gel cassette of the buffer core assembly and the second surface toward the partition assembly thereby sealing at least one electrophoresis gel cassette to the buffer core assembly within the electrophoresis apparatus. 
     
     
         2 . The expanding cam of  claim 1 , wherein the partition assembly comprises a buffer dam, a buffer displacement dam, or a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         3 . The expanding cam of  claim 1 , wherein the partition assembly comprises a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         4 . The expanding earn lock of  claim 1 , wherein the cam is pivotally coupled to the base plate and is configured to slideably engage the follower plate. 
     
     
         5 . The expanding cam lock of  claim 4 , wherein the cam includes axle pins pivotally coupling the cam to the base plate. 
     
     
         6 . The expanding cam lock of  claim 1 , wherein the cam is configured to lock the base plate into engagement with the electrophoresis gel cassette of the buffer core and the follower plate into engagement with the partition assembly when the cam is in the second position. 
     
     
         7 . The expanding cam lock of  claim 1 , wherein the cam includes a push bar configured to engage the base plate to prevent further urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         8 . The expanding cam lock of  claim 1  wherein the cam includes a handle to pivot the cam relative to the base plate and follower plate. 
     
     
         9 . The expanding cam lock of  claim 1 , wherein the cam further has a curved end that slidingly engages the follower plate. 
     
     
         10 . The expanding cam lock of  claim 1 , wherein the first and second surfaces include push tabs adapted to facilitate urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         11 . The expanding cam lock of  claim 1 , wherein the base plate includes first side panels on a reverse side opposing the first surface and the follower plate includes second side panels on a reverse side opposing the second surface, the first and second side panels being coupled together. 
     
     
         12 . The expanding cam lock of  claim 11 , wherein the first side panels include slots and the second side panels include lever arms with locking portions configured to slideably engage the slots. 
     
     
         13 . The expanding cam lock of  claim 1 , wherein at least one of the base plate, the follower plate and the cam is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         14 . An expanding cam lock for sealing at least one electrophoresis gel cassette in an electrophoresis apparatus, the expanding cam lock comprising:
 a base plate having a first surface adapted to engage a first buffer core assembly comprising at least one electrophoresis gel cassette;   a follower plate having second surface adapted to engage a second buffer core assembly comprising at least one electrophoresis gel cassette,   a cam positioned between and moveably coupled with the base plate and the follower plate;   
       wherein, the base plate and the follower plate are slideably coupled together and configured for insertion between the first buffer core assembly and the second buffer assembly in the electrophoresis apparatus, and the cam being movable from a first position to a second position to urge the first surface toward the electrophoresis gel cassette of the first buffer core assembly and the second surface toward the electrophoresis gel cassette of the second buffer core assembly thereby sealing the electrophoresis gel cassettes to the first and second buffer core assemblies within the electrophoresis apparatus. 
     
     
         15 . The expanding cam lock of  claim 14 , wherein the cam is pivotally coupled to the base plate and is configured to slideably engage the follower plate. 
     
     
         16 . The expanding cam lock of  claim 15 , wherein the cam includes axle pins pivotally coupling the cam to the base plate. 
     
     
         17 . The expanding cam lock of  claim 14 , wherein the earn is configured to lock the base plate and follower plate into engagement with the electrophoresis gel cassettes of the buffer cores when the cam is in the second position. 
     
     
         18 . The expanding cam lock of  claim 14 , wherein the cam includes a push bar configured to engage the base plate to prevent further urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         19 . The expanding cam lock of  claim 14 , wherein the cam includes a handle to pivot the cam relative to the base plate and follower plate. 
     
     
         20 . The expanding cam lock of  claim 14 , wherein the cam further has a curved end that slidingly engages the follower plate. 
     
     
         21 . The expanding cam lock of  claim 14 , wherein the first and second surfaces include push tabs adapted to facilitate urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         22 . The expanding cam lock of  claim 14 , wherein the base plate includes first side panels on a reverse side opposing the first surface and the follower plate includes second side panels on a reverse side opposing the second surface, the first and second side panels being coupled together. 
     
     
         23 . The expanding cam lock of  claim 22 , wherein the first side panels include slots and the second side panels include lever arms with locking portions configured to slideably engage the slots. 
     
     
         24 . The expanding cam lock of  claim 23 , wherein least one of the base plate, the follower plate and the cam is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         25 . An electrophoresis kit, comprising
 a) an electrophoresis container having a first end wall defining a first recess and a second end wall defining a second recess;   b) at least one buffer core assembly; and   c) an expanding cam lock, comprising:
 a base plate having a first surface adapted to engage a buffer core assembly and having first side panels on the reverse side of the first surface; 
 a follower plate having a second surface adapted to engage a partition assembly and having second side panels on the reverse side of the second surface, the first and second side panels being slideably coupled and the base plate and follower plate being configured for insertion between the first buffer core assembly and the partition assembly; and 
 a cam pivotally coupled to the base plate and the cam slidingly engaging the follower plate. 
   
     
     
         26 . The electrophoresis kit of  claim 25 , wherein the partition assembly comprises a buffer dam, a buffer displacement dam, or a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         27 . The electrophoresis kit of  claim 26 , wherein the partition assembly comprises a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         28 . The electrophoresis kit of  claim 25 , wherein at least one of the electrophoresis container, the base plate, the follower plate, the cam, the partition assembly and the buffer core assembly is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         29 . The electrophoresis kit of  claim 25 , wherein the cam includes axle pins pivotally coupling the cam to the base plate. 
     
     
         30 . The electrophoresis kit of  claim 25 , wherein the earn is configured to lock the base plate into engagement with the electrophoresis gel cassette of the buffer core and to lock the follower plate into engagement with the partition assembly when the cam is in the second position, 
     
     
         31 . The electrophoresis kit of  claim 25 , wherein the cam includes a push bar configured to engage the base plate to prevent further urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         32 . The electrophoresis kit of  claim 25 , wherein the cam includes a handle to pivot the cam relative to the base plate and follower plate. 
     
     
         33 . The electrophoresis kit of  claim 25 , wherein the cam further comprises a curved end that slidingly engages the follower plate. 
     
     
         34 . The electrophoresis kit of  claim 25 , wherein the first and second surfaces include push tabs adapted to facilitate urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         35 . The electrophoresis kit of  claim 25 , wherein the first side panels include slots and the second side panels include lever arms with locking portions configured to slideably engage the slots. 
     
     
         36 . An electrophoresis assembly, comprising
 a) art electrophoresis container having a first end wall defining a first recess and a second end wall defining a second recess;   b) a buffer core assembly disposed in the container proximate the first end wall;   c) a partition assembly disposed in the container proximate the second end wall; and   d) an expanding cam lock for sealing at least one electrophoresis gel cassette to the buffer core assembly, wherein the expanding cam is positioned between the buffer core assembly and the partition assembly within the electrophoresis container.   
     
     
         37 . The electrophoresis assembly of  claim 36 , wherein the expanding cam lock comprises:
 a base plate having a first surface adapted to engage the buffer core assembly and having first side panels on the reverse side of the first surface;   a follower plate having a second surface adapted to engage the partition assembly, and having second side panels on the reverse side of the second surface, the first and second side panels being slideably coupled and the base plate and follower plate being configured for insertion between the buffer core assembly and the partition assembly; and   a cam pivotally coupled to the base plate and the cam slidingly engaging the follower plate to urge the second surface toward the partition assembly and to urge the first surface to secure one or more electrophoresis gel cassettes in the first buffer core assembly.   
     
     
         38 . The electrophoresis assembly of  claim 36 , wherein the partition assembly comprises a buffer dam, a buffer displacement dam, or a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         39 . The electrophoresis assembly of  claim 38 , wherein the partition assembly comprises a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         40 . The electrophoresis assembly of  claim 36 , wherein at least one of the electrophoresis container, the base plate, the follower plate, the cam, the partition assembly and the buffer core assembly is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         41 . The electrophoresis assembly of  claim 37 , wherein the cam includes axle pins pivotally coupling the cam to the base plate. 
     
     
         42 . The electrophoresis assembly of  claim 37 , wherein the cam is configured to lock the base plate into engagement with the electrophoresis gel cassette of the buffer core and to lock the follower plate into engagement with the partition assembly when the cam is in the second position. 
     
     
         43 . The electrophoresis assembly of  claim 37 , wherein the cam includes a push bar configured to engage the base plate to prevent further urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         44 . The electrophoresis assembly of  claim 37 , wherein the cam includes a handle to pivot the cam relative to the base plate and follower plate. 
     
     
         45 . The electrophoresis assembly of  claim 37 , wherein the cam further has a curved end that slidingly engages the follower plate. 
     
     
         46 . The electrophoresis assembly of  claim 37 , wherein the first and second surfaces include push tabs adapted to facilitate urging of the first surface toward the buffer core assembly and the second surface toward the partition assembly. 
     
     
         47 . The electrophoresis assembly of  claim 37 , wherein the first side panels include slots and the second side panels include lever arms with locking portions configured to slideably engage the slots. 
     
     
         48 . A method for securing an electrophoresis gel cassettes in an electrophoresis container, the method comprising:
 providing a base plate having a first surface adapted to engage a buffer core assembly comprising the electrophoresis gel cassette;   providing a follower plate having second surface adapted to engage a partition assembly, the follower plate being slideably coupled to the base plate;   providing a cam positioned between and moveably coupled with the base plate and the follower plate;   inserting the base plate, the follower plate, and the cam between the buffer core assembly and the partition assembly in the electrophoresis container;   moving the cam from an open position to a closed position to urge the first and second surfaces to secure the gel cassettes to the first and second buffer core assemblies.   
     
     
         49 . The method of  claim 48 , wherein moving the cam to the closed position causes the cam to lock the base plate and the following plate into engagement with the gel cassettes of the first and second buffer core assemblies. 
     
     
         50 . The method of  claim 48 , wherein the partition assembly comprises a buffer dam, a buffer displacement dam, or a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         51 . The method of  claim 50 , wherein the partition assembly comprises a buffer core assembly comprising at least one electrophoresis gel cassette. 
     
     
         52 . An apparatus for electrophoresis or electrophoretic transfer of biomolecules that comprises a buffer displacement dam in at least one buffer reservoir of the apparatus, wherein the buffer displacement dam conforms to the size of the interior of the buffer reservoir in at least one dimension, and wherein the buffer displacement dam replaces buffer that would otherwise be contained within the buffer reservoir during electrophoretic separation or transfer of biomolecules. 
     
     
         53 . The apparatus of  claim 52 , wherein the buffer displacement dam comprises a bottom and at least three sides. 
     
     
         54 . The apparatus of  claim 52 , wherein the buffer displacement dam comprises a bottom and at least four sides. 
     
     
         55 . The apparatus  claim 52 , wherein the buffer displacement dam is solid. 
     
     
         56 . The apparatus of  claim 52 , wherein the buffer displacement dam is partially or substantially hollow. 
     
     
         57 . The apparatus of  claim 54 , wherein the at least four sides of the buffer displacement dam define an interior space. 
     
     
         58 . The apparatus of  claim 57 , wherein the buffer displacement dam comprises one or more interior support structures. 
     
     
         59 . The apparatus of  claim 52 , wherein the buffer displacement dam comprises one or more polymers or copolymers. 
     
     
         60 . The apparatus of  claim 52 , wherein the buffer displacement dam replaces a volume of buffer equal to at least 10% of the total volume of the at least one buffer reservoir. 
     
     
         61 . The apparatus of  claim 52 , wherein the buffer displacement dam replaces a volume of buffer equal to at least 20% of the total volume of the at least one buffer reservoir. 
     
     
         62 . The apparatus of  claim 52 , wherein the buffer displacement dam replaces a volume of buffer equal to at least 30% of the total volume of the at least one buffer reservoir. 
     
     
         63 . The apparatus of  claim 52 , wherein the buffer displacement dam replaces a volume of buffer equal to at least 40% of the total volume of the at least one buffer reservoir. 
     
     
         64 . The apparatus of  claim 52 , wherein the apparatus is an electrophoretic gel blotting apparatus. 
     
     
         65 . The apparatus of  claim 64 , wherein the electrophoretic gel blotting apparatus comprises a buffer reservoir in the form of a buffer tank that comprises at least one gel cassette. 
     
     
         66 . The apparatus of  claim 65 , wherein the at least one gel cassette is smaller than the maximum size of gel cassette that the electrophoretic gel blotting apparatus can accommodate. 
     
     
         67 . The apparatus of  claim 65 , wherein the gel blotting apparatus is designed to accommodate multiple gel cassettes. 
     
     
         68 . The apparatus of  claim 67 , wherein the electrophoretic gel blotting apparatus comprises fewer than the maximum number of gel cassettes it is designed to accommodate. 
     
     
         69 . The apparatus of  claim 52 , wherein the apparatus is a gel electrophoresis apparatus. 
     
     
         70 . The apparatus of  claim 69 , wherein the apparatus comprises fewer than the maximum number of gels it is designed to accommodate. 
     
     
         71 . The apparatus of  claim 69 , wherein the buffer displacement dam replace cathode buffer. 
     
     
         72 . The apparatus of  claim 69 , wherein the buffer displacement dam replaces anode buffer. 
     
     
         73 . The apparatus of  claim 69 , wherein the apparatus comprises a container designed to accommodate multiple buffer cores. 
     
     
         74 . The apparatus of  claim 73 , wherein the apparatus comprises fewer than the maximum number of buffer cores the container is designed to accommodate. 
     
     
         75 . The apparatus of  claim 74 , wherein the buffer displacement dam occupies a position of the container that is designed to hold a buffer core. 
     
     
         76 . The apparatus of  claim 75 , wherein the buffer displacement dam occupies space designed to hold a buffer core and space in the container designed to hold lower reservoir buffer. 
     
     
         77 . The apparatus of  claim 76 , wherein the container is designed to hold two or more buffer cores, wherein the container comprises at least one buffer core, at least one gel cassette, and a buffer displacement dam. 
     
     
         78 . The apparatus of  claim 77 , wherein the buffer displacement dam has at least four walls that define an interior space, and the dimensions of the buffer displacement dam conforms to the inner dimension of one end of the container. 
     
     
         79 . The apparatus of  claim 75 , wherein the buffer displacement dam comprises a wall that can be engaged by a cam lock device for sealing at least one gel cassette to a buffer core in the tank. 
     
     
         80 . The apparatus of  claim 79 , wherein the cam lock device is an expanding cam lock device. 
     
     
         81 . The apparatus of  claim 80 , wherein the gel electrophoresis apparatus is a midi gel apparatus and the buffer displacement dam displace a volume of from about 100 milliliters to about 1,500 milliliters. 
     
     
         82 . The apparatus of  claim 81 , wherein the gel electrophoresis apparatus is a midi gel apparatus and the buffer displacement dam displace a volume of from about 400 milliliters to about 1,000 milliliters, 
     
     
         83 . The apparatus of  claim 82 , wherein the gel electrophoresis apparatus is a midi gel apparatus and the buffer displacement dam displace a volume of from about 500 milliliters to about 750 milliliters. 
     
     
         84 . A buffer displacement dam comprising a bottom and at least four walls that define an interior space, wherein the four walls of the buffer displacement dam conform to the internal dimensions of at least a portion of a container of an electrophoretic transfer apparatus whereby the buffer displacement dam occupies space in the container otherwise occupied by buffer. 
     
     
         85 . The buffer displacement dam of  claim 84 , wherein the buffer displacement dam is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         86 . A buffer displacement dam comprising a bottom and at least four walls that define an interior space, wherein the four walls of the buffer displacement dam conform to the internal dimensions of at least a portion of a buffer reservoir of a gel electrophoresis apparatus whereby the buffer displacement dam occupies space in the buffer reservoir otherwise occupied by buffer. 
     
     
         87 . The buffer displacement dam of  claim 86 , wherein the gel electrophoresis apparatus comprises a buffer tank that can accommodate multiple buffer cores, the buffer displacement dam conforms to the internal dimensions of the buffer tank, and the buffer displacement dam is designed to occupy the position of at least one of the multiple buffer cores when positioned in the buffer tank. 
     
     
         88 . The buffer displacement dam of  claim 87 , wherein when positioned in the buffer tank, the buffer displacement dam occupies the space in the buffer tank that is designed to hold the second buffer core and space in the buffer tank that holds buffer during use of the apparatus in the absence of the buffer displacement dam. 
     
     
         89 . The buffer displacement dam of  claim 88 , comprising at least one surface that can be contacted by a cam when the buffer displacement dam is positioned in the gel apparatus container, wherein the cam can be used to seal at least one gel cassette to a buffer core. 
     
     
         90 . The buffer displacement dam of  claim 89 , wherein the buffer displacement dam conforms to the inner dimensions of one end of the gel apparatus container. 
     
     
         91 . The buffer displacement dam of  claim 86 , wherein the buffer displacement dam is made of a polymer selected from the group consisting of styrene acrylonitrile, polycarbonate, polystyrene, acrylic, acrylate, polymethyl methacrylate, polyethylene, high density polyethylene, polyethylene terephthalate, glycol-modified polyethylene terephthalate, polypropylene, polyoxymethylene, Acetel and copolymers thereof. 
     
     
         92 . The buffer displacement dam of  claim 86 , wherein the gel electrophoresis apparatus is a midi-gel apparatus and the buffer displacement dam fits into a buffer reservoir of the midi-gel apparatus. 
     
     
         93 . The buffer displacement dam of  claim 92 , wherein the displacement dam is from about 3 to about 10 inches in height. 
     
     
         94 . The buffer displacement dam of  claim 93 , wherein the displacement dam is from about 3 to about 6 inches in height. 
     
     
         95 . The buffer displacement dam of  claim 94 , wherein the displacement dam is from about 3.5 to about 5 inches in height. 
     
     
         96 . The displacement dam of  claim 95 , wherein the displacement dam is about 4.5 inches in height. 
     
     
         97 . The displacement dam of  claim 92 , wherein the displacement dam is from about 4 to about 10 inches in length. 
     
     
         98 . The displacement dam of  claim 97 , wherein the displacement dam is from about 4 to about 8 inches in length 
     
     
         99 . The displacement dam of  claim 98 , wherein the displacement dam is about 6.14 inches in length. 
     
     
         100 . The displacement dam of  claim 92 , wherein the displacement dam is from about 1 to about 5 inches in width. 
     
     
         101 . The displacement dam of  claim 100 , wherein the displacement dam is from about 1 to about 3 inches in width. 
     
     
         102 . The displacement dam of claim  1019 , wherein the displacement dam is about 1.66 inches in width. 
     
     
         103 . The buffer displacement dam of  claim 92 , wherein the buffer displacement dam has a lip on one end. 
     
     
         104 . A method of performing electrophoretic transfer of one or more biomolecules from a gel to a filter or membrane, comprising:
 positioning within a buffer tank a gel cassette comprising a transfer membrane and a gel that comprises one or more biomolecules, wherein the buffer tank comprises or contacts two electrodes;   adding a buffer displacement dam to the buffer tank;   adding transfer buffer to the buffer tank;   connecting a power source to the two electrodes; and   applying a voltage across the gel to cause electrophoretic transfer of the one or more biomolecules from the gel to the transfer membrane.   
     
     
         105 . A method of performing electrophoretic separation of one or more biomolecules, comprising:
 positioning at least one gel cassette in a gel electrophoresis apparatus such that one end of a gel enclosed within the gel cassette is in contact with a first buffer reservoir and another end of the gel enclosed within the gel cassette is in contact with a second buffer reservoir, wherein the first buffer reservoir comprises or contacts a first electrode and the second buffer reservoir comprises or contacts a second electrode;   adding a buffer displacement dam to the f gel electrophoresis apparatus;   adding electrophoresis buffer to the first buffer reservoir and the second reservoir;   adding one or more samples comprising one or more biomolecules to sample wells at one end of the gel;   connecting the first electrode and the second electrode to a power source; and   applying a voltage across the gel to separate one or more biomolecules.   
     
     
         106 . A buffer displacement dam for replacing electrophoresis buffer in an electrophoresis apparatus having a tank, an anode reservoir, and a cathode reservoir, wherein the buffer dam comprises nonconductive material and is positioned within a tank of the electrophoresis apparatus in a position otherwise occupied by a buffer core, such that less than 90% of the buffer is present within either the anode reservoir or the cathode reservoir compared to the amount of buffer present in the absence of the buffer displacement dam. 
     
     
         107 . The buffer displacement dam of  claim 106 , wherein the electrophoresis apparatus is a gel electrophoresis apparatus. 
     
     
         108 . The buffer displacement dam of  claim 106 , wherein the electrophoresis apparatus is a gel blotting apparatus. 
     
     
         109 . The buffer displacement dam of  claim 106 , wherein less than 75% of buffer is present than is present in the absence of the buffer displacement dam.