Abstract:
A method of creating an electrophoresis gel having a gel electrophoresis identifier includes providing a surface including a gel electrophoresis identifier marker; providing an electrophoresis gel on the surface having the gel electrophoresis identifier marker; and forming a gel electrophoresis identifier on the electrophoresis gel with the gel electrophoresis identifier marker of the surface. The gel electrophoresis identifier is used to identify and orient the gel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/374,055 filed on Apr. 19, 2002 under 35 U.S.C. 119(e). 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to electrophoresis gel identifiers.  
         BACKGROUND OF THE INVENTION  
         [0003]    Gel electrophoresis is a common procedure for the separation of biological molecules, such as DNA, RNA, and proteins. In gel electrophoresis, the molecules are separated into bands according to the rate at which an imposed electric field causes them to migrate through a filtering gel.  
           [0004]    The basic apparatus used in this technique consists of a gel enclosed in a glass tube or sandwiched as a slab between glass or plastic plates. The gel has an open molecular network structure, defining pores which are saturated with an electrically conductive buffered solution of a salt. These pores through the gel are large enough to admit passage of the migrating molecules.  
           [0005]    The gel is placed in contact with buffer solutions which make electrical contact between the gel and the cathode or anode of an electrical power supply. A sample containing the macromolecules and a tracking dye is placed on top of the gel. An electric potential is applied to the gel causing the sample macromolecules and tracking dye to migrate toward the bottom of the gel. The locations of the bands of separated macromolecules are then determined. By comparing the distance moved by particular bands in comparison to the tracking dye and macromolecules of known mobility, the mobility of sample macromolecules can be determined. Once the mobility of the sample macromolecules is determined, the size of the macromolecule can be calculated.  
           [0006]    Electrophoresis gels are commonly identified by marking the external surface of the plates or carrier with a permanent marker, printed labels, or the like. A problem with this approach is that the identification information is lost if the gel is removed from the plates or carrier for post-separation processing (e.g., staining, transfer).  
           [0007]    When running several gels at one time, it is important to know which gel contains which samples. Further, it is important when running a gel to know which lane contains which sample. Because gels often have symmetrical sample lanes, distinguishing the left side from the right side is imperative for determining where the samples are located.  
           [0008]    In order to distinguish one gel from another as well as the left side and right side of the gel, a common practice is to load special samples in a particular pattern that uniquely identifies each gel run as well as the gel&#39;s orientation. This special pattern loading technique complicates the electrophoresis process and may consume extra sample wells when large numbers of gels are run at once. Alternatively, corners of the gels may be cut off when removing the gels from the carriers to distinguish one gel from another. This technique may work for marking the proper orientation of a small number of gels at one time, but is not practical for marking the proper orientation of a large number of gels. Another method of identifying gels is to mark, for example, by imprinting, the containers in which the respective gels are processed. This can be problematic since the user must take great care not to mix up the gels once they are dissociated with their respective containers, which could place the validity of the gel run in question.  
           [0009]    Therefore, a need exists to solve both the gel orientation and identification problems described above so that the user is free to load samples in the most convenient manner, without having to additionally mark or label the carrier.  
         SUMMARY OF THE INVENTION  
         [0010]    An aspect of the invention involves a method of making an electrophoresis gel having a gel electrophoresis identifier includes providing a surface having a gel electrophoresis identifier marker; providing an electrophoresis gel on the surface including the gel electrophoresis identifier marker; and forming a gel electrophoresis identifier on the electrophoresis gel with the gel electrophoresis identifier marker of the surface. The gel electrophoresis identifier is used to identify and orient the gel.  
           [0011]    Another aspect of the invention involves an electrophoresis carrier including a transparent front carrier member including an inner side, a transparent rear carrier member including an inner side, and an electrophoresis gel sandwiched between the inner sides of the transparent front carrier member and the transparent rear carrier member. At least one of the inner sides of the transparent front carrier member and the transparent rear carrier member including a gel electrophoresis identifier marker that contacts the electrophoresis gel to form a gel electrophoresis identifier on the electrophoresis gel to identify and orient the gel.  
           [0012]    A further aspect of the invention involves a method of identifying and orienting an electrophoresis gel including providing an electrophoresis gel including an embossed electrophoresis gel identifier, and using the embossed electrophoresis gel identifier to identify and orient the gel.  
           [0013]    Further objects and advantages will be apparent to those skilled in the art after a review of the drawings and the detailed description of the preferred embodiments set forth below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a perspective view of a thin, plastic-film gel electrophoresis assembly including an embodiment of an electrophoresis gel identifier marker.  
         [0015]    [0015]FIG. 2 is a top plan view of a support frame of the thin, plastic-film gel electrophoresis assembly illustrated in FIG. 1.  
         [0016]    [0016]FIG. 3 is a top plan view of a first, inner thin-film member including an embodiment of the electrophoresis gel identifier marker.  
         [0017]    [0017]FIG. 4 is a top plan view of a second, outer thin-film member. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]    With reference to FIG. 1, a thin, plastic-film gel electrophoresis assembly  100  will first be generally described, followed by a description of an embodiment of an electrophoresis gel identifier marker.  
         [0019]    The assembly  100  includes a support frame  110  that carries a gel sandwiched between a first, rear, inner thin-film member  120  and a second, front, outer thin-film member  130 . A reservoir  140  is detachably mounted to a top  150  of the support frame  110 .  
         [0020]    The reservoir  140  includes an upper portion  160 , and intermediate portion  170 , and a lower portion  180  that gradually tapers in thickness from a wide, open top  190 , where samples are introduced, to a narrow, open bottom  200 , where the samples electrophoretically migrate from a first gel in the reservoir  140  to a second gel sandwiched between the thin-film members  120 ,  130 . The upper portion  160  has a trough-like configuration. The lower portion  180  may include a plurality of divided wells. Mounting mechanisms  210 ,  220  extend from opposite ends  230 ,  240  of the reservoir  140 . Each mounting mechanism  210 ,  220  includes a first, small, front laterally protruding member  250  and a parallel second, large, rear laterally protruding member  260 .  
         [0021]    With reference additionally to FIG. 2, the support frame  110  will now be described in more detail. The support frame  110  is made of a flexible, resilient plastic material and has a substantially rectangular configuration with a central rectangular hole  270  and a substantially flat face  275 . The support frame  110  includes an upper lateral support  280 , a lower lateral support  290 , a left vertical support  300 , and a right vertical support  310 . The vertical supports  300 ,  310  terminate at their tops  150  in ear-like protrusions  320 ,  330 . The ear-like protrusions  320 ,  330  are slidably received between the front and rear protruding members  250 ,  260  of the mounting mechanisms  210 ,  220  for detachably mounting the reservoir  140  to the support frame  110 .  
         [0022]    A fixed support post  340  extends outwardly from the right vertical support  310  near an upper-right corner of the support frame  110 . The support post  340  includes an undercut on a right portion of the support post  340 .  
         [0023]    A support post  360  extends outwardly from the left vertical support  300  near an upper-left corner of the support frame  110 . The support post  360  is connected to the left vertical support  300  via a flexible, resilient, straight connection member  370 . Similar to a spring, the connection member  370  provides a biasing force in a direction opposite to that in which it is displaced. The connection member  370  may be moved laterally, forward, and rearward. The support post  360  includes an undercut that extends around the entire circumference of the support post  360 , except where the support post  360  is attached to the connection member  370 .  
         [0024]    A support post  380  extends outwardly from the left vertical support  300  near a lower-left corner of the support frame  110 . The support post  380  is connected to the left vertical support  300  via a flexible, resilient, curved, hook-shaped connection member  390 . Similar to a spring, the connection member  390  provides a biasing force in a direction opposite to that in which it is displaced. The connection member  390  may be moved up and to the right, down and to the left, forward, and rearward. Because the connection member  390  is curved, if the connection member  390  is displaced, for example, upward and toward the right, the connection member  390  will provide a biasing force in an opposite direction, namely, downward and toward the left. The support post  380  includes an undercut that extends around a lower-left portion of the circumference of the support post  380 .  
         [0025]    A support post  400  extends outwardly from the right vertical support  310  near a lower-right corner of the support frame  110 . The support post  400  is connected to the right vertical support  310  via a flexible, resilient, curved, hook-shaped connection member  410 , similar to the connection member  390 . If the connection member  410  is displaced, for example, upward and toward the left, the connection member  410  will provide a biasing force in an opposite direction, namely, downward and toward the right. The connection member  410  may be moved up and to the left, down and to the right, forward, and rearward. The support post  400  includes an undercut similar to the undercut that extends around a lower-right portion of the circumference of the support post  380 .  
         [0026]    With reference to FIGS. 1 and 3, the inner thin-film member  120  and an embodiment of the electrophoresis gel identifier marker will now be described. The inner thin-film member  120  is preferably a thin, rectangular piece of plastic, transparent film such as cellophane film and may include the second gel disposed on a front side or inner side  420 . The inner thin-film member  120  includes four holes  430 ,  440 ,  450 ,  460  that receive the four support posts  340 ,  360 ,  380 ,  400  in a manner to be described. A small, upper-right hole  430  is circular. An upper-left hole  440  is laterally elongated to allow for lateral movement of the upper-left support post  360  therein. A lower-left hole  450  has a round, diamond shape and is larger than the upper-right hole  430 . A lower-right hole  460  is similar in shape and size to the lower-left hole  450 . A clipped corner  470  of the inner thin-film member  120  may help in orienting the inner thin-film member  120  when mounting it to the support frame  110 .  
         [0027]    The inner side  420  may include a permanent electrophoresis gel identifier marker  472  in a lower portion and on the inner side  420  of the inner thin-film member  120 . The identifier marker  472  may be an engraving, scribing or etching on the inner side  420  of the inner thin-film member  120 . The identifier marker  472  may include one or more of a name, a serial number, an alphanumeric identifier, or other indicia for creating a like identifier on the gel for identifying the gel and the samples run in the gel. When the electrophoresis gel is cast or otherwise added to the inner side  420  of the inner thin-film member  120 , the resulting gel fills in and around the identifier marker  472 , creating a corresponding permanent embossed identifier on the surface of the gel.  
         [0028]    The permanent electrophoresis gel identifier marker  472  may be created on the inner side  420  of the inner thin-film member  120  using a CO 2  laser scribe. An exemplary laser scribe that may be used is the Model DGM-1 Laser Scribe from the Domino company of Anaheim, Calif. The CO 2  laser was set to a 15% power level for use on 100 micrometer (0.1 mm) thick polyester films such as the Gel-Fix for Agarose or the Gel-Fix for PAG film sold by Serva Electrophoresis GmbH of Heidelberg, Germany. Other scribing instruments may be used to create the identifier marker  472  on the inner side  420  of the thin-film plastic member  120  such as, but not by way of limitation, a scratch awl, a diamond pen, and an electric scribe. In the embodiment of the electrophoresis gel identifier marker  472  shown, a phrase and serial number are scribed onto the inner side  420  of the inner thin-film member  120  to make a corresponding unique embossed identifier on the resulting electrophoresis gel cast onto the inner side  420 . Exemplary electrophoresis gels include agarose, polymerizing cross-linked Acrylamide using either usual chemical or photo initiators, combinations of agarose and acrylamide, or other appropriate matrixes that change from a fluid consistency to a gel.  
         [0029]    Although the electrophoresis gel identifier marker  472  has been described as being located on an inner side  420  and in a lower portion of the inner thin-film member  120 , the identifier marker  472  may be located at one or more additional or alternative locations to the lower portion on the inner side  420  of the inner thin-film member  120  such as, but not by way of limitation, near a right edge and/or left edge of the inner thin-film member  120 . The electrophoresis gel identifier marker  472  is preferably located in an area where sample may not be present because the identifier marker  472  may change the thickness or chemical properties of the mold sufficient to distort the resulting electrophoresis separation of samples run over the identifier marker  472 .  
         [0030]    Although the identifier marker  472  has been described as being located on an inner side of thin-film plastic member  120 , the identifier marker  472  may be located on the inner surface of any gel carrier or casting apparatus (e.g., glass plates, plastic plates).  
         [0031]    With reference to FIG. 4, the outer thin-film member  130  will now be described. The outer thin-film member  130  is preferably a thin, substantially rectangular piece of plastic, transparent film such as cellophane film. The outer thin-film member  130  includes four holes  480 ,  490 ,  500 ,  510  that receive the four support posts  340 ,  360 ,  380 ,  400  in a manner to be described. A small, upper-right hole  480  and upper-left hole  490  are circular. A lower-left hole  500  and a lower-right hole  510  have round, diamond shapes and are larger than the upper holes  480 ,  490 . The left holes  490 ,  500  are closer to the right holes  480 ,  510  than the corresponding holes in the outer thin-film member  130 . A tabbed corner  520  of the outer thin-film member  130  may be used to handle the outer thin-film member  130  and may help orient the outer thin-film member  130  when mounting it to the support frame  110 . Similar to the inner thin-film member  120 , the outer thin-film member  130  may include an inner side with an electrophoresis gel identifier marker  472 .  
         [0032]    During assembly of the gel, the gel is cast on the inner thin-film member  130 . The resulting gel fills in and around the laser-scribed electrophoresis gel identifier marker  472 , causing a corresponding embossed identifier to be formed on the back surface of the gel, which abuts the inner side  420  of the inner thin-film member  130 . Because the gel and thin-film members  120 ,  130  are transparent, the identifier on the back surface of the gel is visible when looking at the gel and film members  120 ,  130  from a front perspective. The identifier on the gel serves as a permanent descriptive label on the gel that may be used to uniquely identify the gel and the samples run on the gel after separation. Although the identifier has been described as being located on the surface of the gel, in an alternative embodiment, the identifier may be located within the gel. Locating the identifier on the gel overcomes the problems in the past with identifying electrophoresis gels by marking the external surface of the plates or carrier. The identifier on the gel helps the user in orienting the gel because when the identifier can be read in a normal left-to-right fashion the user knows the gel is properly oriented. This eliminates the orientation problems with gels and carriers in the past.  
         [0033]    It will be readily apparent to those skilled in the art that still further changes and modifications in the actual concepts described herein can readily be made without departing from the spirit and scope of the invention as defined by the following claims.