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Avirachan T Tharapel

Publications and source records attributed to Avirachan T Tharapel.

6 recordsLinked to original sources
PubMed2006

PRINS for the detection of gene deletions in cancer.

The chromosomal regions 13q14 and 17p13 often are found rearranged in hematopoietic tumors in humans, but the rearrangements can be subtle and can escape detection on gross cytogenetic analysis. For example, submicroscopic perturbations of the RB1 and p53 tumor suppressor genes, located in 13q14 and 17p13, respectively, frequently occur in leukemias; this has been confirmed by molecular methods such as fluorescence in situ hybridization (FISH). Our group modified the primed in situ labeling (PRINS) method to study RB1 and p53 in cultured bone marrow cells from leukemia patients with known deletions within the 13q14 or 17p13 regions. Locus-specific oligonucleotide probes ("PRINS primers") were annealed to chromosomal DNA on glass slides and extended in the presence of the four trinucleotide precursors, biotin-16-dUTP, and Taq DNA polymerase. After addition of avidin-conjugated fluorophores, the resulting signals could be visualized by fluorescence microscopy in metaphase spreads and interphase nuclei of controls but were absent in the corresponding preparations from patients. The results of these and similar studies suggest that with further development, PRINS might be used as a convenient and rapid alternative to FISH in the delineation of deletions involving single genes or unique sequences.

Biotin↗
PubMed2006

PRINS for the detection of unique sequences.

Primed in situ labeling (PRINS) can be used to localize single-copy genes and unique sequences. Using a modified PRINS method that incorporates multiple primers for the same sequence, single-step annealing and extension, anti-Taq DNA polymerase antibody, and stringent washing, we localized the human SRY gene to Yp11.31-p11.32 in chromosome preparations in situ. Locus-specific oligonucleotide probes (i.e., PRINS primers) were annealed to chromosomal DNA fixed on glass slides and extended in the presence of the four trinucleotide precursors, biotin-16-2'-deoxyuridine 5'-triphosphate, Tris-HCl, KCl, MgCl2, bovine serum albumin, and Taq DNA polymerase. After reaction with avidin-conjugated fluorophores, the resulting signals could be visualized by fluorescence microscopy in metaphase spreads and in interphase nuclei. This method could prove useful for unique sequences in general.

Base Sequence↗
PubMed2006

PRINS for mapping single-copy genes.

Primed in situ labeling (PRINS) is a sensitive and specific method that can be used for the localization of single copy genes and sequences too small for detection by conventional fluorescence in situ hybridization. By the use of PRINS, the human SRY gene was localized to Yp11.31-p11.32 and the SOX3 gene to Xq26-q27. In other studies, we localized specific deletions of RBM and DAZ, candidate genes for AZF (azoospermia factor) to proximal Yq11.2, the AZF region, in an infertile male. Locus-specific oligonucleotide probes (PRINS primers) were annealed to chromosomal DNA in situ and extended on preparations fixed on glass slides in the presence of dATP, dCTP, dGTP, dTTP, biotin-16-dUTP, and Taq DNA polymerase. After addition of avidin-conjugated fluorophore, signals were visualized by fluorescence microscopy in metaphase spreads from patients and controls. With further development, the PRINS method may prove useful for localization of single-copy genes, in general, and for the detection of gene deletions.

Base Sequence↗
PubMed2002

Prader Willi/Angelman and DiGeorge/velocardiofacial syndrome deletions: diagnosis by primed in situ labeling (PRINS).

A recently developed methodology-primed in situ labeling (PRINS)-can be used in place of fluorescence in situ hybridization (FISH) to diagnose microdeletions. To demonstrate the efficiency, sensitivity, and specificity of PRINS in the diagnosis of microdeletions, we studied groups of patients with Prader Willi/Angelman (PWS/AS) syndrome and DiGeorge/velocardiofacial syndrome (DGS/VCFS). Results obtained by PRINS were then confirmed with the results obtained with FISH. Oligonucleotide primers specific for SNRPN and GABRB3 were used for PWS/AS syndromes. For DGS/VCFS, the primers used were DGCR2/TUPLE1 loci. Labeling patterns obtained by PRINS and FISH were analyzed and scored under a fluorescence microscope. Five normal subjects served as controls and were used for standardization of the PRINS protocol. In all, 20 study patients were involved: 10 PWS/AS and 10 DGS/VCFS. Five of the 10 patients referred with the clinical diagnosis of PWS/AS showed absence of labeling for SNRPN and GABRB3 on one chromosome 15, confirming deletion of the two loci. Similarly, 6 of the 10 patients referred for DGS/VCFS showed deletion for the DGCR2/TUPLE1 loci on one chromosome 22. The remaining patients and controls had normal patterns for all the loci as indicated by FISH and PRINS. Concordant FISH and PRINS results were obtained in all patients and controls studied.

Angelman Syndrome↗
PubMed2002

Deletion of RBM and DAZ in azoospermia: evaluation by PRINS.

Molecular and cytogenetic studies from infertile men have shown that one or more genes controlling spermatogenesis are located in proximal Yq11.2 in interval 6 of the Y chromosome. Microdeletions within the azoospermia factor region (AZF) are often associated with azoospermia and severe oligospermia in men with idiopathic infertility. We evaluated cells from a normal-appearing 27-year-old man with infertility and initial karyotype of 45,der(X)t(X;Y)(p22.3;p11.2)[8]/46,t(X;Y)(p22.3;p11.2)[12]. By fluorescence in situ hybridization with dual-color whole chromosome paint probes for X and Y chromosomes, we confirmed the Xp-Yp interchange. By primed in situ labeling, we identified translocation of the SRY gene from its original location on Yp to the patient's X chromosome at band Xp22. We also obtained evidence that the apparent marker was a der(Y) (possibly a ring) containing X and Y domains, and observed that the patient's genome was deleted for RBM and DAZ, two candidate genes for AZF.

Adult↗