Chemistry: electrical and wave energy – Processes and products – Electrophoresis or electro-osmosis processes and electrolyte...
Reexamination Certificate
2000-01-06
2002-01-29
Warden, Jill (Department: 1743)
Chemistry: electrical and wave energy
Processes and products
Electrophoresis or electro-osmosis processes and electrolyte...
C204S466000, C204S613000, C204S616000, C435S287100
Reexamination Certificate
active
06342143
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
BACKGROUND OF THE INVENTION
In the field of molecular biology, many tools have been developed for analyzing biomolecules. One such tool, electrophoresis, enables one to separate biomolecules, such as DNA, RNA and protein, based upon size, shape and/or charge. A mixture of biomolecules are placed in small wells in a gel, typically, a polyacrylamide gel, and a charge is applied which separates the biomolecules into discrete bands. The ability to separate biomolecules allows for the isolation and purification of many different biomolecule samples or bands in a single gel. Once isolated, a single band can be analyzed to determine a purified biomolecule's unique properties. In addition, isolation of purified biomolecules facilitates diagnosis of certain diseases and other biological abnormalities.
Isolation of the samples has had some shortcomings. One of these shortcomings is cross-sample contamination, which can occur when the same scalpel or razor blade is used to excise different biomolecules from the gel. To isolate samples, the area of the gel containing the desired band is cut with a scalpel or razor blade. Conventional gel cutting tools, such as the tool described in U. S. Pat. No. 5,587,062, do not provide for replacement of the cutting tool for each gel sample excised. Therefore, only one contamination-free sample can be excised. Subsequent samples can not be excised using the same cutting tool without contamination.
Agarose gels are used to grow bacteria and other microorganisms. An agarose plate is streaked, for example, with a sample to be tested. Microorganisms typically grow in plaques on the gel. The plaques can be excised from the gel. The contamination problems that exist with electrophoresis gels are also experienced with agarose gels.
As a result, there is a need for a gel cutting apparatus capable of multiple sample retrieval without cross-contamination from previously excised samples.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a sample retrieval apparatus that includes a support platform, a support translation member for moving the support platform to designated coordinates on X and Y axes, a cutter member, a cutter translation assembly for moving the cutter member to designated positions on a Z axis, the Z axis lying in a plane perpendicular to the support platform, and, a controller for designating the X, Y axis coordinates of the support platform and the Z axis positions of the cutter member. The support translation member has an elongate X rail lying on the X axis and an elongate Y rail lying on the Y axis. The X and Y rails each lie on a plane parallel to the other and are operatively connected to each other to permit relative travel of the X and Y rails along the length of the other. The support translation member also includes at least one motor for effecting such travel.
The support platform is preferably slidably mounted for travel along the length of the X rail and the X rail is slidably mounted for travel along the length of the Y rail. Alternatively, the support platform is slidably mounted for travel along the length of the Y rail and the Y rail is slidably mounted for travel along the length of the X rail.
The cutter member preferably includes a cutter tip having a proximal engagement end and a distal cutting and retrieval end. The cutter tip defines a passage therethrough. A plunger having a proximal engagement portion is preferably provided for slidable movement through the passage of the cutter tip.
The cutter translation assembly preferably includes a motor and a shaft operatively connected to the motor for movement along the Z axis. The shaft has an engagement sleeve for releasable engagement of the engagement end of the cutting tip. A coupling member is received within the sleeve for releasable engagement with the engagement portion of the plunger.
In an alternative embodiment, the cutter tip does not include the plunger and the plunger forms part of the cutter translation assembly.
In the preferred embodiment, the distal cutting end of the cutter tip is configured for cutting into a section of gelatinous material for retrieving and holding the section of material. There are preferably a plurality of disposable cutter tips with associated disposable plungers. Alternatively, the cutter tips and associated plungers may be reusable following appropriate cleaning or sterilization.
The support platform is configured to hold at least one gelatinous sample container, at least one array of cutter members and at least one transfer container. The configuration may take the form of clasps to hold the various elements in place, precisely configured depressions or raised boundaries for receiving the various elements.
An imager is provided for providing images of samples positioned on the support platform in the sample containers. A display unit is preferably provided for receiving and displaying images of the samples from the imager. The controller, which is preferably a computer in communication with the support translation member and the cutter translation assembly, may have an input device for selecting sample sections represented by the sample images displayed on the display unit that are to be retrieved and a memory and execution tool for determining the X, Y coordinates of the selected sample section on the support platform, determining the distance between the sample X, Y coordinates and moving the X, Y coordinates of the point of intersection between the Z axis and the support platform, and moving the support platform that distance such that the selected sample is aligned with the Z axis and moving the cutter member along the Z axis into position for cutting and retrieving the selected section of the sample.
The present invention also provides a method for retrieving one or more selected samples from a gel. The method may include positioning at least one gel containing samples of interest, a plurality of cutter tips and at least one receiving container on a support platform; taking an image of the gel and displaying the image; and selecting a sample from the displayed image of the gel for retrieval. Thereafter, the support platform is moved to first coordinates along an X axis and a Y axis to place the one of the plurality of cutter tips into alignment with a cutter member. The cutter member is moved into contact with the cutter tip to attach it to the cutter member. The cutter member and the now attached cutter tip are moved out of contact with the plurality of cutter tips. The method continues by moving the support platform to second coordinates along the X and Y axes to place the selected sample into alignment with the cutter member, moving the cutter member along a Z axis into contact with the selected sample, piercing the portion of the gel containing the selected sample with the cutter tip, and withdrawing the cutter member to retrieve the selected sample. Then, the support platform is moved to third coordinates along the X and Y axes to place a receiving container in alignment with the cutter member. The selected sample is released to the receiving container. Where retrieval of additional samples is desired, the method further includes releasing the cutter tip following release of the selected sample and repeating the foregoing steps for each of a desired number of different samples using a different one of the plurality of cutter tips for each sample retrieval.
The invention is particularly useful in the field of molecular biology for rapidly collecting numerous specified fractions of samples of biomolecules, such as nucleic acid fragments, DNA, RNA or protein, that are separated by gel electrophoresis; or microorganisms, such as bacteria or yeast that is grown on agarose plates. The apparatus of the present invention is capable of multiple sample retrieval from such gels without cross-contamination from previously excised samples.
REFERENCES:
patent: 4938593 (1990-07-01), Morris et al.
patent: 5217591 (1993-06-01), Gombocz et al.
patent: 5587062 (1996-12-
Carnegie Mellon University
Kirkpatrick & Lockhart LLP
Noguerola Alex
Warden Jill
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