Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Process of storage or protection
Reexamination Certificate
1998-04-09
2001-07-10
Warden, Jill (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Process of storage or protection
C422S105000, C435S002000, C435S260000, C435S307100
Reexamination Certificate
active
06258320
ABSTRACT:
BACKGROUND OF THE INVENTION
Amber is a natural, amorphous, polymeric glass which is formed from the fossilized resin of plants. The plant resins from which amber originates comprise complex mixtures of terpenoid compounds, acids, alcohols, and essential oils. As the resin ages, it becomes harder and forms a semifossilized product known as copal. Amber and copal are distinguished by their physical characteristics, e.g., melting point, hardness, and solubility. In particular, amber has mechanical, dielectric, and thermal features common to synthetic polymeric glasses.
Natural inclusions in amber represent organic material such as pieces of leaves or small insects that were trapped in the plant resins before the liquid resin hardened. The chemical structure of the resin changes during fossilization, e.g., the linking of isoprene units such as diterpenoids causes inert dehydration of organic materials present in the amber.
Insects trapped in amber have been studied for many years because they can provide valuable clues to entomologists regarding the phylogeny of species. Recently, it has been discovered that “ancient” DNA can be recovered from samples of insects or plants trapped in amber, even though the estimated age of the species has been over many millions of years in some cases (Cano,
Endeayor,
20, 162 (1996); DeSalle and Grimaldi,
Current Op. Genet
, &
Devel.,
4, 810 (1994); Poinar,
Experieltia,
50, 536 (1994)). However, the ancient DNA in fossilized amber is often present at very low concentrations and may be quite degraded. While an amplification reaction, e.g., the polymerase chain reaction (PCR), can increase the concentration of DNA recovered from amber to detectable levels (Cano et al., U.S. Pat. No. 5,593,883), contamination during the DNA recovery process or subsequent analysis, and the presence of amplification inhibitors in the sample, e.g., tannins, porphyrins, heme and the like, can render PCR-derived results unreliable or unobtainable.
The integrity of ancient DNA which is embedded in amber may be compromised by oxidation of the DNA bases, a reaction that affects the ability of PCR to correctly amplify DNA sequences (Paabo et al.,
J. Biol. Chem.,
265, 4718 (1990)). Oxidation reactions, however, are not directly involved in the breakage of the DNA backbone. DNA integrity may also be affected by depurination (hydrolysis of the deoxyribose/adenine or guanine bond), followed by a &bgr;-elimination reaction that results in chain breakage. This reaction is thought to be the main reaction important in the fragmentation of DNA in the geologic environment. Nevertheless, based on studies of the retardation of the racemization of amino acids in insect tissues embedded in amber, Bada et al. (
Geochim. Cosmo. Acta,
58,3131 (1994)) suggested that the breakdown of DNA embedded in amber might be inhibited.
Preservation of isolated and/or purified biological samples, e.g., isolated protein or nucleic acid, is often accomplished by storing the sample at low temperature, e.g., at −20° C. or −70° C. Low temperature slows natural biological and chemical processes, which can lead to the degradation of cellular components such as carbohydrates, proteins and nucleic acids. Moreover, the lower the temperature, the slower the degradation process. For example, complex cellular samples, e.g., sperm and eggs, are frozen and stored in a container having liquid nitrogen, which maintains the sample at about −200° C. However, to preserve the sample, the level of liquid nitrogen in the container must be carefully monitored and the container must be periodically replenished with liquid nitrogen.
Thus, there is a need for an improved method to preserve isolated vertebrate nucleic acid.
SUMMARY OF THE INVENTION
A system for the long-term storage or preservation of isolated nucleic acid derived or obtained from a vertebrate source, e.g., a mammal such as a human, is provided. Such long-term storage may be desirable for several reasons. First, the nucleic acid, present in largely intact form, may be used for retrospective genetic analysis. Second, the genomic nucleic acid content of a vertebrate represents a highly individualized biological substance that is unique to that particular organism. Storage of nucleic acid, preferably genomic DNA, in largely intact form would thus represent an identification means for that vertebrate. Also, the storage of genomic nucleic acid in intact form is desirable to provide a unique, personalized composition, for example, to wear as jewelry.
Thus, the invention provides a method for long-term maintenance of a sample of intact, isolated nucleic acid. The method comprises introducing an amount of isolated vertebrate nucleic acid into at least one recess, cavity or hollow of a receptacle. The nucleic acid may be genomic DNA, RNA or cDNA derived from RNA. As used herein, the term “derived” with respect to a RNA molecule means that the RNA molecule has complementary sequence identity to a particular DNA molecule. Preferably, the nucleic acid is genomic DNA obtained from a mammalian physiological sample, e.g., genomic DNA isolated from mammalian peripheral blood cells. The isolated nucleic acid sample represents a population of molecules, preferably a population which has not been subjected to an in vitro enzymatic amplification reaction.
A preferred receptacle of the invention is hollow and has an aperture or opening to permit access to the hollow interior of the receptacle. After introducing the nucleic acid sample into the recess, cavity or hollow interior of the receptacle, a fastening means or sealant is then placed into the aperture or opening of the receptacle leading to the recess, cavity or interior of the receptacle to form a nucleic acid containing receptacle. Thus, the fastening means or sealant retains the nucleic acid in the recess, cavity or interior of the receptacle.
Prior to the introduction of the fastening means, the nucleic acid containing receptacle is optionally subjected to conditions which reduce, inhibit or prevent the degradation of the nucleic acid, e.g., dehydration and/or the replacement of an oxygen-containing atmosphere (air) with an inert gas, such as argon or nitrogen. Subsequent to the fastening or sealing step, the nucleic acid containing receptacle is placed into a recess, cavity or hollow of a storage device. A second fastening means or sealant is then introduced into the aperture of the recess, cavity or hollow so as to retain the nucleic acid containing receptacle in the recess, cavity or hollow, thus yielding a nucleic acid storage device.
Also provided is a method to prepare a support device for long-term storage of vertebrate nucleic acid. The method comprises introducing a nucleic acid containing receptacle into a recess, cavity or hollow of a storage device. The nucleic acid containing receptacle comprises a depot or receptacle, e.g., a hollow sphere, having an amount of isolated vertebrate nucleic acid in a recess, cavity or hollow of the depot or receptacle. The isolated nucleic acid is retained in the recess, cavity or hollow by a fastening means such as a screw or preformed plug. A sealant is introduced into the aperture of the hollow of the device so as to retain the nucleic acid containing receptacle in the recess, cavity or hollow of the device, yielding a nucleic acid storage device.
Further provided is a nucleic acid storage device prepared by the methods of the invention. The device may be the basis for a jewelry product, e.g., in a ring, bracelet, earring or necklace, a decorative item, e.g., a mantelpiece, or as a form of identification.
The invention also provides a method for long-term maintenance of intact nucleic acid. In this embodiment of the invention, an amount of isolated vertebrate nucleic acid is introduced into a recess of a receptacle through an aperture. The aperture of the recess is then sealed so that the nucleic acid is retained in the recess. This yields a nucleic acid containing receptacle. It is preferred that the receptacle is formed from amber or copal.
Yet another
Persing David H.
Persing Susan H.
Persing David H.
Schwegman Lundberg Woessner & Kluth P.A.
Warden Jill
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