Abstract: A novel limited primer extension reaction improves detection sensitivity and specificity in a variety of hybridization platforms. In the invention, a sequence of target DNA that lacks one of the four types of nucleic acid bases for a span of eight or more adjacent nucleotide positions is selected for use. This sequence is referred to as the extension complement sequence, or ECS. A primer with a sequence that is complementary to the target sequence that is immediately downstream (to the 3? side) of this ECS is used to initiate an extension reaction. Extension occurs using a DNA polymerase and standard deoxynucleoside triphosphates for three of the four types of nucleic acid bases. The fourth base, which is complementary to the base missing in the ECS, is either absent or present only in the form of a dideoxynucleoside triphosphate, which does not support further extension. In either case, the extension reaction does not proceed past the first occurrence in the template of the base that is missing in the ECS.

Abstract: The present invention is directed to a method of extracting nucleic acids from samples containing prokaryotic cells and/or eukaryotic cells by (a) lysing the cells under conditions that minimize RNA expression or enzymatic degradation of RNA; (b) dispersing and diluting the lysed cells; (c) mixing the dispersed and diluted lysed cells with a buffered solution containing cationic and anionic detergents; (d) separating non-nucleic acid contaminants from the nucleic acids by mixing with an organic extraction solvent to generate an emulsion that separates into an organic phase, an interface containing the contaminants and an aqueous phase containing the nucleic acids; (e) separating the phases, and retaining the aqueous phase; and (f) precipitating the nucleic acids in the aqueous phase.

Abstract: A novel limited primer extension reaction improves detection sensitivity and specificity in a variety of hybridization platforms. In the invention, a sequence of target DNA that lacks one of the four types of nucleic acid bases for a span of eight or more adjacent nucleotide positions is selected for use. This sequence is referred to as the extension complement sequence, or ECS. A primer with a sequence that is complementary to the target sequence that is immediately downstream (to the 3? side) of this ECS is used to initiate an extension reaction. Extension occurs using a DNA polymerase and standard deoxynucleoside triphosphates for three of the four types of nucleic acid bases. The fourth base, which is complementary to the base missing in the ECS, is either absent or present only in the form of a dideoxynucleoside triphosphate, which does not support further extension. In either case, the extension reaction does not proceed past the first occurrence in the template of the base that is missing in the ECS.

Abstract: A novel polymeric nucleic acid probe improves detection sensitivity and specificity in a variety of hybridization platforms. The probe is made up of multiple short nucleic acid sequences (referred to as monomers) attached together to form a long polymeric probe for use in hybridization applications. For applications requiring immobilization of the probes to a surface, the polymeric probes are similar to long DNA probes in that they can be immobilized to a variety of surfaces without need for a chemical modification to the end of the probe. Because target nucleic acids hybridize to the relatively short monomers in the polymeric probe, the polymeric probes are more specific than long DNA probes. In addition, polymeric probes also improve the signal-to-background ratio by increasing the number of accessible monomer oligonucleotide probes immobilized per unit area on a surface.

Abstract: A process for deoxyribonucleic acid (DNA) sequencing, mapping, and diagnostics which utilizes the differences between the chemical composition of DNA and that of peptide nucleic acids (PNAs) to provide DNA sequencing, mapping, or diagnostics using natural DNA fragments, rather than using radioisotopes, stable isotopes or fluorescent substances to label the DNAs. The process includes the steps of hybridizing PNA segments to complementary DNA segments which are fixed to a hybridization surface, or hybridizing DNA segments to complementary PNA segments which are fixed to a hybridization surface, and using mass spectrometric or non-mass spectrometric techniques to analyze the extent of hybridization at each potential hybridization site.

Abstract: A DNA sequencing, mapping, and diagnostic process which includes the steps of labeling nucleotide segments or peptide nucleic acids (PNAs) with one or more atoms of specific stable or long-lived radioactive isotopes of a selected element that do not normally occur in DNAs, ODNs or PNAs such that the nucleotide segment or PNA has specific stable or long-lived radioactive isotope of a specified selected element at a terminal or an interior position; hybridizing the labeled nucleotide segment or PNA to complementary nucleic acid segments or PNAs which are fixed on a hybridization surface; and, using mass spectrometric techniques, including RIS, to analyze the presence and position of the labeled hybridized nucleotide segments or PNAs which are bound to the fixed nucleotide segments or PNAs.

Abstract: A DNA sequencing process using specific stable isotopes associated with specific terminators for labels. The process includes a step of incorporating a stable isotope in at least one of the deoxynucleoside triphosphates and/or the dideoxynucleoside triphosphates such that a terminated strand has included within it or at the end a stable isotope such as an isotope of sulphur. Replicated strands are then separated by performing gel electrophoresis thereon. The location of the DNA strand with the stable isotope assigned to a terminator is analyzed preferably by resonance ionization spectroscopy. The stable isotopes can be chosen such that specific labels are assigned to at least one, and preferably to each base, in the dideoxynucleoside triphosphates. In the preferred embodiment, each of the bases (A, T, G and C) are associated with a specific stable isotopic label, and can be analyzed in a single track which enhances the accuracy of the sequencing process.

Abstract: Isotope analysis device comprising a racetrack-shaped ion storage ring, a resonant charge exchange device and a laser photoionization device. Isotope ions to be analyzed are continuously injected into the racetrack in a first orbit and pass through the resonant charge exchange device where they are neutralized and decelerated to produce decelerated isotope particles. Selected isotope particles are then re-ionized by the laser photoionization device, and the resulting selected isotope ions travel around the racetrack in a smaller orbit, while the undesired non-ionized particles exit the storage ring and are separately collected. After several succesively decreasing ion orbits, each isotope of the desired species reaches a detector where it is measured. The device is particularly useful for isotope analysis of strontium and of krypton.

Abstract: An ultrasensitive mass spectrometry method based on multiphoton sub-Doppler resonance ionization to measure abundance sensitivities. The method preferentially ionizes a selected isotope in a sample by using Doppler-free resonant multiphoton ionization to produce an enhanced ratio of selected isotopes. Background species are separately ionized and rejected. As necessary or desired, selected isotope ions are preferentially ionized by using a second Doppler-free resonant multiphoton ionization to provide an additional isotope enhancement. The ions produced are injected into a mass spectrometer. Isotopic spectrum analysis of the ions is performed by the spectrometer and the ions are then detected by a detector such as a particular photon multiplier capable of observing a single ion. In one embodiment, at least one of the steps of preferentially ionizing the selected isotope is accomplished by two counter propagating laser beams of slightly different frequencies.

Abstract: A dosimeter which incorporates new methods for determining neutron dose. Less than one millirad of dose due to neutrons of all energies down to approximately 10.sup.3 eV can be measured, and the response can be adjusted by design of the dosimeter. The dosimeter utilizes the sputtering of material from a target due to the action of the neutrons and measuring of the amount of sputtered material to determine the dose. The sputtered material may be, for example, a noble gas or an inert solid. Various radiator materials can be included to interact with the neutrons so that the resulting charged particles control the sputtering process and hereby increase the sensitivity of the dosimeter. The target material can be, for example, noble-gas-impregnated polycrystalline or amorphous metals. The sputtered material is analyzed using resonance ionization spectroscopy, sputter-initiated resonance ionization spectroscopy or other methods to determine its quantity and hence the neutron dose.

Abstract: An improved method of operating a time-of-flight mass spectrometer. This method, which involves double pulsing, achieves an increase in the resolution of TOF mass spectrometers by compensating for the energy spread of the species extracted from the source and thus the time spread of ions of a specific mass arriving at a detector. According to this improved method, atoms (or molecules) for analysis are rapidly removed from a surface at a first well defined time. These atoms or molecules are then rapidly ionized at a location or region a distance, R, from the surface at a second well defined time after a selected time delay, T.sub.o. The resultant ions first move through a region of uniform electric field of a distance, S.sub.1, and then into a field-free region having a length, S.sub.2, Lastly, ions leaving the field-free region enter a short high energy accelerating region so as to impinge upon an ion detector.

Abstract: Method and apparatus for determining small quantities of specific atoms with isotopic selectivity. According to the method described herein, atoms are rapidly released from an atom bank containing the same, and are then converted to ions utilizing resonance ionization as achieved with photon beams having specific wave lengths. These ions are extracted from the ionization region and are accelerated and implanted into a second atom bank. For further selectivity, the atoms are then rapidly released from the second bank, ionized with another photon beam of selected wave length to provide ionization of the desired species, with these ions then being extracted, subjected to acceleration, and implanted into the first atom bank. Typically the number of electrons emitted from the atom banks during implantation is used as a measure of the number of atoms of the selected species.

Abstract: An ultrasensitive mass spectrometry method based on multiphoton sub-Doppler resonance ionization is used to measure abundance sensitivities. The method preferentially ionizes a selected isotope in a sample by using Doppler-free resonant multiphoton ionization to produce an enhanced ratio of selected isotopes. As necessary or desired, selected isotope ions are preferentially ionized by using a second Doppler-free resonant multiphoton ionization to provide an additional isotope enhancement. The ions produced are injected into a mass spectrometer (24). Isotopic spectrum analysis of the ions is performed by the spectrometer (24) and the ions are then detected by a detector (26) such as a particular photon multiplier capable of observing a single ion. In one embodiment, at least one of the steps of preferentially ionizing the selected isotope is accomplished by two counter propagating laser beams of slightly different frequencies.

Abstract: Apparatus and method are described for the quantitative analysis of a specific specie within a sample. The analysis has sufficient sensitivity for the detection of as little as one atom of the desired species. The method is accomplished by bombarding a sample with a highly focused charged particle beam; for example, a beam of positive argon ions having an energy from five to thirty kilovolts and a current of one milliampere or greater. This beam impinging upon the sample creates a cloud including secondary ions and neutral particles of the constituents of the sample. The cloud is irradiated with a laser beam having selected wavelengths therein for the unique ionization of the desired specie by means of resonance ionization spectroscopy (RIS). In most applications some energy and/or mass discrimination is required. The energy discrimination can be accomplished by passing the RIS ions through an energy filter, with the ions emanating therefrom having a narrow range of energy.

Abstract: Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10.sup.-8 Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample.