Physical methods of detecting the binding of complementary strands of коронавирус новости сегодня 12 февраля 2020 коронавирус новости сегодня 12 февраля 2020 DNA or RNA are well known in the art, and include such methods as DNase I or chemical footprinting, gel shift and affinity cleavage assays, Northern blotting, Southern blotting, dot blotting, and light absorption detection procedures.
For example, a method which is widely used, because it is so simple and reliable, involves observing a change in light absorption of a solution containing an oligonucleotide (or an analog) and a target nucleic acid at 220 to 300 nm as the temperature is slowly increased. If the oligonucleotide or analog has bound to its target, there is a sudden increase in absorption at a characteristic temperature as the oligonucleotide (or analog) and target dissociate or melt. The binding between an oligomer and its target nucleic acid is frequently characterized by the temperature (T m ) at which 50% of the oligomer is melted from its target.
A higher T m means a stronger or more stable complex relative to a complex коронавирус новости сегодня 12 февраля 2020 with a lower T m . cDNA (complementary DNA): A piece of DNA lacking internal, non-coding segments (introns) and regulatory sequences that determine transcription. cDNA is synthesized in the laboratory by reverse transcription from messenger RNA extracted from cells. Electrophoresis: Electrophoresis refers to the migration of charged solutes or particles in a liquid medium under the influence of an electric field. Electrophoretic separations are widely used for analysis of коронавирус новости сегодня 12 февраля 2020 macromolecules. Of particular importance is the identification of proteins and nucleic acid sequences. Such separations can be based on differences in size and/or charge. Nucleotide sequences have a uniform charge and are therefore separated based on differences in size. Electrophoresis can be performed in an unsupported liquid medium (for example, capillary electrophoresis), but more commonly the liquid medium travels through a solid supporting medium. The most widely used supporting media are gels, for example, polyacrylamide and agarose gels.
Sieving gels (for example, agarose) impede the flow of molecules. The pore size of the gel determines the size of a molecule that can flow freely through the gel. The amount of time to travel коронавирус новости сегодня 12 февраля 2020 through the gel increases as the size of the molecule increases. As a result, small molecules travel through the gel more quickly than large molecules and thus progress further from the sample application area коронавирус новости сегодня 12 февраля 2020 than larger molecules, in a given time period. Such gels are коронавирус новости сегодня 12 февраля 2020 used for size-based separations of nucleotide sequences. Fragments of linear DNA migrate through agarose gels with a mobility that is inversely proportional to коронавирус новости сегодня 12 февраля 2020 the log 10 of their molecular weight. By using gels with different concentrations of agarose, different sizes of DNA fragments can be resolved.
Higher concentrations of agarose facilitate separation of small DNAs, while low agarose concentrations allow resolution of larger DNAs. Hybridization: Oligonucleotides and their коронавирус новости сегодня 12 февраля 2020 коронавирус новости сегодня 12 февраля 2020 analogs hybridize by hydrogen bonding, which includes Watson-Crick, Hoogsteen or reversed Hoogsteen hydrogen bonding, between complementary bases. Generally, nucleic acid consists of nitrogenous bases that are either pyrimidines (cytosine (C), uracil (U), and thymine (T)) or purines (adenine (A) and guanine (G)).
These nitrogenous bases form hydrogen bonds between a pyrimidine and a purine, and the bonding of the pyrimidine to the purine is referred to as “base pairing.” More specifically, A will hydrogen bond to T or U, and G will bond to C. “Complementary” refers to the base pairing that occurs between to distinct nucleic acid sequences or two distinct regions of the same nucleic acid sequence. “Specifically hybridizable” and “specifically complementary” are terms that indicate a sufficient degree of complementarity such that stable and specific binding occurs between the oligonucleotide (or its analog) and the DNA or RNA target. The oligonucleotide or oligonucleotide analog need not be 100% complementary to its target sequence to be коронавирус новости сегодня 12 февраля 2020 specifically hybridizable. An oligonucleotide or analog is specifically hybridizable when binding of the oligonucleotide or analog to the target DNA or RNA molecule interferes with the normal function of the target DNA or RNA, and there is a sufficient degree of complementarity to avoid non-specific binding of the oligonucleotide or analog to non-target sequences under conditions where specific binding is desired, for example under physiological conditions in the case of in vivo assays or systems.
Such binding is referred to as specific hybridization. Hybridization conditions resulting in particular degrees of stringency will vary depending upon the nature of the hybridization method of choice and the composition and length of the hybridizing nucleic acid sequences. Generally, the temperature of hybridization and the ionic strength (especially the Na + and/or Mg ++ concentration) of the hybridization buffer will коронавирус новости сегодня 12 февраля 2020 determine the stringency of hybridization, though wash times also influence stringency.
Calculations коронавирус новости сегодня 12 февраля 2020 regarding hybridization conditions required for attaining particular degrees of stringency are discussed by Sambrook et al. (ed.), Molecular Cloning: A Laboratory Manual, 2 nd ed., vol. 1–3, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989, chapters 9 and 11; and Ausubel et al. Short Protocols in Molecular Biology, 4 th ed., John Wiley & Sons, Inc., 1999.
For purposes of the present disclosure, “stringent conditions” encompass conditions under which hybridization will only occur if there коронавирус новости сегодня 12 февраля 2020 is less than 25% mismatch between the hybridization molecule and the target sequence.
“Stringent conditions” may be broken down into particular levels of stringency for more precise definition. Thus, as used herein, “moderate stringency” conditions are those under which molecules with more than 25% sequence mismatch will not hybridize; conditions of “medium stringency” are those under which molecules with more than 15% mismatch will not hybridize, and conditions of “high stringency” are those under which sequences with more than 10% mismatch will not hybridize. Conditions of “very high stringency” коронавирус новости сегодня 12 февраля 2020 are those under which sequences with more than 6% mismatch will not hybridize.
Immune Stimulatory Composition: A term used herein to mean a composition useful for stimulating or eliciting a specific immune response (or immunogenic response) in a vertebrate.
In some embodiments, the immunogenic response is protective or provides protective immunity, in that it enables the vertebrate animal to better resist infection with or disease progression from the коронавирус новости сегодня 12 февраля 2020 organism against which the vaccine is directed. Without wishing to be bound коронавирус новости сегодня 12 февраля 2020 by a specific theory, it is believed that an immunogenic response may arise from the generation of an antibody specific to one коронавирус новости сегодня 12 февраля 2020 or more of the epitopes provided in the immune stimulatory composition.
Alternatively, the response may comprise a T-helper or cytotoxic cell-based response to one or more of the epitopes provided in the immune stimulatory composition. All three of these responses may originate from naive or memory cells. One specific example of a type of immune stimulatory composition is a vaccine. In some embodiments, an “effective amount” or “immune-stimulatory коронавирус новости сегодня 12 февраля 2020 amount” of an immune stimulatory composition is an amount which, when administered to a subject, is sufficient to engender a detectable immune response.
