Poly T
Poly A
Poly(ADP-ribose) Polymerases
Poly C
Poly U
Poly I-C
Poly dA-dT
Poly(A)-Binding Proteins
Poly Adenosine Diphosphate Ribose
Poly G
Poly I
Polydeoxyribonucleotides
Poly(A)-Binding Protein I
Polynucleotide Adenylyltransferase
Polyribonucleotides
Polyesters
Poly(A)-Binding Protein II
Movement of nuclear poly(A) RNA throughout the interchromatin space in living cells. (1/195)
BACKGROUND: Messenger RNA (mRNA) is transcribed and processed in the nucleus of eucaryotic cells and then exported to the cytoplasm through nuclear pores. It is not known whether the movement of mRNA from its site of synthesis to the nuclear pore is directed or random. Directed movement would suggest that there is an energy-requiring step in addition to the step required for active transport through the pore, whereas random movement would indicate that mRNAs can make their way to the nuclear envelope by diffusion. RESULTS: We devised a method to visualize movement of endogenous polymerase II transcripts in the nuclei of living cells. Oligo(dT) labeled with chemically masked (caged) fluorescein was allowed to penetrate cells and hybridize to nuclear poly(A) RNA. Laser spot photolysis then uncaged the oligo(dT) at a given intranuclear site and the resultant fluorescent, hybridized oligo(dT) was tracked using high-speed imaging microscopy. Poly(A) RNA moved away from the uncaging spot in all directions with a mean square displacement that varied linearly with time, and the same apparent diffusion coefficient was measured for the movement at both 37 degrees C and 23 degrees C. These properties are characteristic of a random diffusive process. High resolution three-dimensional imaging of live cells containing both Hoechst-labeled chromosomes and uncaged oligo(dT) showed that, excluding nucleoli, the poly(A) RNA could access most, if not all, of the non-chromosomal space in the nucleus. CONCLUSIONS: Poly(A) RNA can move freely throughout the interchromatin space of the nucleus with properties characteristic of diffusion. (+info)Polymorphic variation at the BAT-25 and BAT-26 loci in individuals of African origin. Implications for microsatellite instability testing. (2/195)
Instability in the repeat size of microsatellite sequences has been described in both hereditary nonpolyposis and sporadic colorectal cancers. Tumors expressing microsatellite instability are identified through the comparison of the repeat sizes at multiple microsatellite loci between tumor and matched normal tissue DNA. The use of a five-marker panel including two mononucleotide repeat microsatellites, BAT-25 and BAT-26, has recently been suggested for the clinical determination of tumor microsatellite instability. The BAT-25 and BAT-26 loci included in this panel have both demonstrated sensitivity to microsatellite instability and normal quasimonomorphic allelic patterns, which has simplified the distinction between normal and unstable alleles. However, in this study, we identified allelic variations in the size of the poly(A) tract at BAT-26 in 12.6% of 103 healthy African-Americans screened. In addition, 18.4% exhibited allelic size variations in the poly(T) tract at BAT-25. Finally, 2.9% showed variant alleles at both BAT-25 and BAT-26 loci. Screening a small population of Nigerians confirmed the polymorphic nature of both loci and the ethnic origin of alleles not identified in other populations studied thus far. Our results dispute the quasimonomorphic nature of both BAT-25 and BAT-26 in all populations and support the need for thorough population studies to define the different allelic profiles and frequencies at microsatellite loci. (+info)Mutational and pH studies of the 3' --> 5' exonuclease activity of bacteriophage T4 DNA polymerase. (3/195)
The 3' --> 5' exonuclease activity of proofreading DNA polymerases requires two divalent metal ions, metal ions A and B. Mutational studies of the 3' --> 5' exonuclease active center of the bacteriophage T4 DNA polymerase indicate that residue Asp-324, which binds metal ion A, is the single most important residue for the hydrolysis reaction. In the absence of a nonenzymatic source of hydroxide ions, an alanine substitution for residue Asp-324 reduced exonuclease activity 10-100-fold more than alanine substitutions for the other metal-binding residues, Asp-112 and Asp-219. Thus, exonuclease activity is reduced 10(5)-fold for the D324A-DNA polymerase compared with the wild-type enzyme, while decreases of 10(3)- to 10(4)-fold are detected for the D219A- and D112A/E114A-DNA polymerases, respectively. Our results are consistent with the proposal that a water molecule, coordinated by metal ion A, forms a metal-hydroxide ion that is oriented to attack the phosphodiester bond at the site of cleavage. Residues Glu-114 and Lys-299 may assist the reaction by lowering the pK(a) of the metal ion-A coordinated water molecule, whereas residue Tyr-320 may help to reorient the DNA from the binding conformation to the catalytically active conformation. (+info)Urinary thymine dimers and 8-oxo-2'-deoxyguanosine in psoriasis. (4/195)
Psoralen in conjunction with UVA (PUVA) is perhaps the most effective treatment for psoriasis. It is, however, a risk factor for skin cancer in these patients and there is a need to develop non-invasive assays reflective of treatment-induced DNA damage. We report here the assessment of two important lesions, thymine dimer (T<>T) and 8-oxo-2'-deoxyguanosine (8-OHdG), in the urine of psoriasis patients. It was found that, once corrected for urine concentration, the psoriatic group had significantly higher (P<0. 0001) urinary levels of thymine dimers compared to the control group. No significant differences in urinary 8-OHdG levels were noted between the psoriatic, atopic dermatitis and control groups. Therefore biomonitoring of therapy from the very start with this simple and non-invasive assay could perhaps be an effective measure of the risk involved with the treatment allowing optimization for minimal-risk therapy. (+info)Ribonuclease H of calf thymus: substrate specificity, activation, inhibition. (5/195)
When the action of highly purified specimens of ribonuclease H (hybrid nuclease; RNA-DNA hybrid ribonucleotidohydrolase; EC 3.1.4.34) of calf thymus on a wide selection of homopolymer hybrids was studied, the extent, and even the occurrence, of hydrolysis was found to be governed by the interplay of several factors: the composition of the ribo strand, the length of the deoxyribo strand, and the nature of the activating metal. Mn2+ activates the enzymic cleavage of all hybrid combinations, Mg2+ only of those containing purine ribo strands, Co2+ only of poly(A) hybrids. A 1:1 hybrid of phage f1 DNA and RNA is, however, split in the presence of any of these activators. Hybrids with deoxyribo tetranucleotides can still be cleaved, but not with dinucleotides. The behavior of hybrids containing covalently linked runs of ribo and deoxyribopolynucleotides was studied with the hybrid poly(dT)-poly(A)7-(dA)X]. This hybrid is attacked by ribonuclease H so that the bulk of the resulting poly(dA) still retains one covalently linked riboadenylic acid end group, whereas a small proportion carries a ribo dinucleotide. Inhibition studies showed that ribonuclease H is inactivated irreversibly by pretreatment with S-adenosylmethionine at 35 degrees, but not at 0 degrees. S-Adenosylhomocysteine also is inhibitory, but not irreversibly; also it is essentially limited to the inhibition of the cleavage of purine ribo strands. When the enzyme is exposed simultaneously to both inhibitors, irreversible inactivation is diminished considerably. (+info)Sequence-dependent variation in DNA minor groove width dictates orientational preference of Hoechst 33258 in A-tract recognition: solution NMR structure of the 2:1 complex with d(CTTTTGCAAAAG)(2). (6/195)
The solution structure of the dodecamer duplex d(CTTTTGCAAAAG)(2)and its 2:1 complex with the bis -benzimidazole Hoechst 33258 has been investigated by NMR and NOE-restrained molecular dynamics (rMD) simulations. Drug molecules are bound in each of the two A-tracts with the bulky N-methylpiperazine ring of each drug located close to the central TG (CA) step, binding essentially to the narrow minor groove of each A-tract. MD simulations over 1 ns, using an explicit solvation model, reveal time-averaged sequence-dependent narrowing of the minor groove from the 3'-end towards the 5'-end of each TTTT sequence. Distinct junctions at the TpG (CpA) steps, characterised by large positive roll, low helical and propeller twists and rapid AT base pair opening rates, add to the widening of the groove at these sites and appear to account for the bound orientation of the two drug molecules with the N-methylpiperazine ring binding in the wider part of the groove close to the junctions. Comparisons between the free DNA structure and the 2:1 complex (heavy atom RMSD 1.55 A) reveal that these sequence-dependent features persist in both structures. NMR studies of the sequence d(GAAAAGCTTTTC)(2), in which the A-tracts have been inverted with the elimination of the TpG junctions, results in loss of orientational specificity of Hoechst 33258 and formation of multiple bound species in solution, consistent with the drug binding in a number of different orientations. (+info)Phage display of ScFv peptides recognizing the thymidine(6-4)thymidine photoproduct. (7/195)
Solar ultraviolet (UV) radiation induces DNA photoproducts in skin cells and is the predominant cause of human skin cancers. To understand human susceptibility to skin cancer and to facilitate the development of prevention measures, highly specific reagents to detect and quantitate UV-induced DNA adducts in human skin will be needed. One approach towards this end is the use of monoclonal antibody-based molecular dosimetry methods. To facilitate the development of photoproduct-specific antibody reagents we have: (i) cloned and sequenced a single chain variable fragment (ScFv) gene coding for one such high affinity monoclonal antibody, [alpha]UVssDNA-1 (mAb C3B6), recognizing the thymidine(6-4)thymidine photoproduct; (ii) expressed and displayed the cloned ScFv gene on the surface of phage; (iii) selected functional recombinant phage by panning; (iv) purified the ScFv peptide; (v) shown that the purified ScFv peptide binds to UV-irradiated polythymidylic acid but not unirradiated polythymidylic acid. This is the first demonstration of the use of phage display to select a ScFv recognizing DNA damage. In addition, this is the initial step towards immortalizing the antibody gene for genetic manipulation, structure-function studies and application to human investigations. (+info)Response of Xenopus Cds1 in cell-free extracts to DNA templates with double-stranded ends. (8/195)
Although homologues of the yeast checkpoint kinases Cds1 and Chk1 have been identified in various systems, the respective roles of these kinases in the responses to damaged and/or unreplicated DNA in vertebrates have not been delineated precisely. Likewise, it is largely unknown how damaged DNA and unreplicated DNA trigger the pathways that contain these effector kinases. We report that Xenopus Cds1 (Xcds1) is phosphorylated and activated by the presence of some simple DNA molecules with double-stranded ends in cell-free Xenopus egg extracts. Xcds1 is not affected by aphidicolin, an agent that induces DNA replication blocks. In contrast, Xenopus Chk1 (Xchk1) responds to DNA replication blocks but not to the presence of double-stranded DNA ends. Immunodepletion of Xcds1 (and/or Xchk1) from egg extracts did not attenuate the cell cycle delay induced by double-stranded DNA ends. These results imply that the cell cycle delay triggered by double-stranded DNA ends either does not involve Xcds1 or uses a factor(s) that can act redundantly with Xcds1. (+info)I'm sorry for any confusion, but "Poly T" is not a standard medical term that I am aware of. It is possible that it could be an abbreviation or shorthand used in a specific context, such as a medical report or research study. If you have more information about where this term came from or how it is being used, I may be able to provide a more accurate and helpful response.
However, if "Poly T" is meant to refer to polycythemia vera, which is a type of blood cancer characterized by an overproduction of red blood cells, then here's the definition:
Polycythemia Vera (PV) is a myeloproliferative neoplasm (MPN), a type of blood cancer that affects the bone marrow. In PV, the body produces too many red blood cells, white blood cells, and platelets, leading to an increased risk of blood clots, enlargement of the spleen, and other complications. The exact cause of PV is not known, but it is thought to be related to genetic mutations that affect the regulation of cell growth and division in the bone marrow. Symptoms of PV can include fatigue, headache, dizziness, shortness of breath, and a bluish or reddish tint to the skin. Treatment for PV typically involves medications to reduce the production of blood cells, as well as regular monitoring to manage complications and prevent progression of the disease.
"Poly A" is an abbreviation for "poly(A) tail" or "polyadenylation." It refers to the addition of multiple adenine (A) nucleotides to the 3' end of eukaryotic mRNA molecules during the process of transcription. This poly(A) tail plays a crucial role in various aspects of mRNA metabolism, including stability, transport, and translation. The length of the poly(A) tail can vary from around 50 to 250 nucleotides depending on the cell type and developmental stage.
I'm sorry for any confusion, but "Poly C" is not a widely recognized medical term or abbreviation in the field of medicine or biology. It might be a typographical error or a shorthand notation used in a specific context. If you could provide more context or clarify what you mean by "Poly C," I would be happy to help further.
I'm sorry for any confusion, but "Poly U" is not a recognized medical term or abbreviation in the English language. It could potentially refer to Polytechnic University or Hong Kong Polytechnic University, but it does not have a specific medical connotation. If you have more context or information, I'd be happy to help further!
Poly(I):C is a synthetic double-stranded RNA (dsRNA) molecule made up of polycytidylic acid (poly C) and polyinosinic acid (poly I), joined by a 1:1 ratio of their phosphodiester linkages. It is used in research as an immunostimulant, particularly to induce the production of interferons and other cytokines, and to activate immune cells such as natural killer (NK) cells, dendritic cells, and macrophages. Poly(I):C has been studied for its potential use in cancer immunotherapy and as a vaccine adjuvant. It can also induce innate antiviral responses and has been explored as an antiviral agent itself.
"Poly A-U" is not a standard medical term. However, in biochemistry and genetics, "poly A" and "poly U" refer to repeating sequences of adenine (A) or uracil (U) nucleotides in DNA or RNA molecules, respectively.
"Poly A" is a post-transcriptional modification that occurs in mRNA, where multiple adenine nucleotides are added to the 3' end of the transcript. This process is important for the stability and translation of mRNA in eukaryotic cells.
"Poly U," on the other hand, can be found in some RNA molecules such as in the 3' untranslated region (UTR) of certain mRNAs or in specific types of non-coding RNAs like U-rich small nuclear RNAs (snRNAs).
Therefore, "Poly A-U" may refer to alternating sequences of adenine and uracil nucleotides in a DNA or RNA molecule. However, it is essential to consider the context in which this term is used to provide an accurate interpretation.
"Poly dA-dT" is not a medical term, but rather a molecular biology term that refers to a synthetic double-stranded DNA molecule. It is composed of two complementary strands: one strand consists of repeated adenine (dA) nucleotides, while the other strand consists of repeated thymine (dT) nucleotides. The "poly" prefix indicates that multiple units of these nucleotides are linked together in a chain-like structure.
This type of synthetic DNA molecule is often used as a substrate for various molecular biology techniques, such as in vitro transcription or translation assays, where it serves as a template for the production of RNA or proteins. It can also be used to study the interactions between DNA and proteins, such as transcription factors, that bind specifically to certain nucleotide sequences.
Poly(ADP-ribose) (PAR) is not strictly referred to as "Poly Adenosine Diphosphate Ribose" in the medical or biochemical context, although the term ADP-ribose is a component of it. Poly(ADP-ribose) is a polymer of ADP-ribose units that are synthesized by enzymes called poly(ADP-ribose) polymerases (PARPs).
Poly(ADP-ribosyl)ation, the process of adding PAR polymers to target proteins, plays a crucial role in various cellular processes such as DNA repair, genomic stability, and cell death. In medical research, alterations in PAR metabolism have been implicated in several diseases, including cancer and neurodegenerative disorders. Therefore, understanding the function and regulation of poly(ADP-ribose) is of significant interest in biomedical sciences.
I'm sorry for any confusion, but "Poly G" does not have a specific medical definition. The term "poly" is a prefix in medicine that means many or multiple, and "G" could potentially refer to a variety of things (such as a genetic locus or a grade), but without more context it's impossible to provide an accurate medical definition for this term.
If you have a specific medical question or concern, I would be happy to try to help you with that. Please provide some additional context or clarify what you mean by "Poly G."
I'm sorry for any confusion, but "Poly I" is not a recognized medical term or abbreviation in the context of human diseases or conditions. It's possible that there might be a typo or misunderstanding in your query. If you intended to ask about a specific medical condition, medication, or concept, please provide the full and correct term so I can give you an accurate and helpful response.
I'm sorry for any confusion, but "Polydeoxyribonucleotides" is not a widely recognized or established medical term. It seems to be a made-up or very obscure term that combines "poly," meaning many, "deoxy," referring to the lack of a hydroxyl group at the 2' carbon position in the ribose sugar, and "ribonucleotides," which are the building blocks of RNA.
If you meant "Polydeoxynucleotides" instead, it would refer to long, synthetic chains of deoxynucleotides, which are the building blocks of DNA. These chains can be used in various biochemical and biological research applications, such as studying enzyme mechanisms or constructing genetic circuits.
Polynucleotide adenylyltransferase is not a medical term per se, but rather a biological term used to describe an enzyme that catalyzes the addition of adenine residues to the 3'-hydroxyl end of polynucleotides. In other words, these enzymes transfer AMP (adenosine monophosphate) molecules to the ends of DNA or RNA strands, creating a chain of adenine nucleotides.
One of the most well-known examples of this class of enzyme is terminal transferase, which is often used in research settings for various molecular biology techniques such as adding homopolymeric tails to DNA molecules. It's worth noting that while these enzymes have important applications in scientific research, they are not typically associated with medical diagnoses or treatments.
Polyribonucleotides are long, chain-like molecules composed of multiple ribonucleotide monomers. Ribonucleotides themselves consist of a ribose sugar, a phosphate group, and one of the four nitrogenous bases: adenine (A), uracil (U), guanine (G), or cytosine (C). In polyribonucleotides, these ribonucleotide monomers are linked together by ester bonds between the phosphate group of one monomer and the ribose sugar of another.
These molecules play crucial roles in various biological processes, such as encoding genetic information, regulating gene expression, catalyzing chemical reactions, and serving as structural components within cells. Some examples of polyribonucleotides include messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA), and small nuclear RNA (snRNA).
In a medical context, polyribonucleotides may be used in therapeutic applications, such as gene therapy or vaccines. For instance, synthetic mRNAs can be designed to encode specific proteins, which can then be introduced into cells to stimulate the production of those proteins for various purposes, including immunization against infectious diseases or cancer treatment.
I'm sorry for any confusion, but "Polyesters" is not a medical term. It is a term used in materials science and textile industry to describe a type of synthetic fiber made from polymers characterized by the presence of ester groups in their main chain. If you have any questions related to medical terminology or concepts, I'd be happy to help with those instead!
In the context of medical definitions, polymers are large molecules composed of repeating subunits called monomers. These long chains of monomers can have various structures and properties, depending on the type of monomer units and how they are linked together. In medicine, polymers are used in a wide range of applications, including drug delivery systems, medical devices, and tissue engineering scaffolds. Some examples of polymers used in medicine include polyethylene, polypropylene, polystyrene, polyvinyl chloride (PVC), and biodegradable polymers such as polylactic acid (PLA) and polycaprolactone (PCL).