Multi-parameter analyses of three-dimensionally cultured tumor spheroids based on respiratory activity and comprehensive gene-expression profiles.

Anal Biochem. 2013 Apr 26;

Authors: Zhou Y, Arai T, Horiguchi Y, Ino K, Matsue T, Shiku H

Abstract
Multicellular spheroids of human breast cancer cells (MCF-7) formed with two different three-dimensional (3D) culture methods were evaluated in detail on the basis of respiratory activity and high-throughput gene expression analysis. The spheroids formed with poly(dimethylsiloxane) (PDMS) microwell arrays indicated significant restriction of the spheroid size whereas their respiratory activity was 2-fold greater than that formed with hanging drop culture method. Fluidigm Biomark dynamic array was used for comprehensive and qRT-PCR analysis on the samples whose respiratory activity had been measured. Genes involved in cellular senescence, glucose metabolism indicated significantly higher for PDMS microwell culture method than for hanging drop culture method (P < 0.05). Interestingly, samples formed with PDMS microwell culture method showed stronger responses for glycolysis than those formed with hanging drop method. These results illustrate the power of multi-parameter analysis to characterize multicellular spheroids cultured in different microenvironment even if they have the same morphology.

PMID: 23628321 [PubMed - as supplied by publisher]

Identification of 99 novel mutations in a worldwide cohort of 1,056 patients with a nephronophthisis-related ciliopathy.

Hum Genet. 2013 Apr 5;

Authors: Halbritter J, Porath JD, Diaz KA, Braun DA, Kohl S, Chaki M, Allen SJ, Soliman NA, Hildebrandt F, Otto EA, The GPN Study Group

Abstract
Nephronophthisis-related ciliopathies (NPHP-RC) are autosomal-recessive cystic kidney diseases. More than 13 genes are implicated in its pathogenesis to date, accounting for only 40 % of all cases. High-throughput mutation screenings of large patient cohorts represent a powerful tool for diagnostics and identification of novel NPHP genes. We here performed a new high-throughput mutation analysis method to study 13 established NPHP genes (NPHP1-NPHP13) in a worldwide cohort of 1,056 patients diagnosed with NPHP-RC. We first applied multiplexed PCR-based amplification using Fluidigm Access-Array™ technology followed by barcoding and next-generation resequencing on an Illumina platform. As a result, we established the molecular diagnosis in 127/1,056 independent individuals (12.0 %) and identified a single heterozygous truncating mutation in an additional 31 individuals (2.9 %). Altogether, we detected 159 different mutations in 11 out of 13 different NPHP genes, 99 of which were novel. Phenotypically most remarkable were two patients with truncating mutations in INVS/NPHP2 who did not present as infants and did not exhibit extrarenal manifestations. In addition, we present the first case of Caroli disease due to mutations in WDR19/NPHP13 and the second case ever with a recessive mutation in GLIS2/NPHP7. This study represents the most comprehensive mutation analysis in NPHP-RC patients, identifying the largest number of novel mutations in a single study worldwide.

PMID: 23559409 [PubMed - as supplied by publisher]

High throughput HLA genotyping using 454 sequencing and the Fluidigm Access Array™ system for simplified amplicon library preparation.

Tissue Antigens. 2013 Mar;81(3):141-9

Authors: Moonsamy PV, Williams T, Bonella P, Holcomb CL, Höglund BN, Hillman G, Goodridge D, Turenchalk GS, Blake LA, Daigle DA, Simen BB, Hamilton A, May AP, Erlich HA

Abstract
The human leukocyte antigen (HLA) class I and class II loci are the most polymorphic genes in the human genome; distinguishing the thousands of HLA alleles is challenging. Next generation sequencing of exonic amplicons with the 454 genome sequence (GS) FLX System and Conexio Assign ATF 454 software provides high resolution, high throughput HLA genotyping for eight class I and class II loci. HLA typing of potential donors for unrelated bone marrow donor registries typically uses a subset of these loci at high sample throughput and low cost per sample. The Fluidigm Access Array System enables the incorporation of 48 different multiplex identifiers (MIDs) corresponding to 48 genomic DNA samples with up to 48 different primer pairs in a microfluidic device generating 2304 parallel polymerase chain reactions (PCRs). Minimal volumes of reagents are used. During genomic PCR, in this 4-primer system, the outer set of primers containing the MID and the 454 adaptor sequences are incorporated into an amplicon generated by the inner HLA target-specific primers each containing a common sequence tag at the 5' end of the forward and reverse primers. Pools of the resulting amplicons are used for emulsion PCR and clonal sequencing on the 454 Life Sciences GS FLX System, followed by genotyping with Conexio software. We have genotyped 192 samples with 100% concordance to known genotypes using 8 primer pairs (covering exons 2 and 3 of HLA-A, B and C, and exon 2 of DRB1, 3/4/5 and DQB1) and 96 MIDs in a single GS FLX run. An average of 166 reads per amplicon was obtained. We have also genotyped 96 samples at high resolution (14 primer pairs covering exons 2, 3, and 4 of the class I loci and exons 2 of DRB1, 3/4/5, DQA1, DQB1, DPB1, and exon 3 of DQB1), recovering an average of 173 sequence reads per amplicon.

PMID: 23398507 [PubMed - in process]

Integrated Fluidic Circuits (IFCs) for Digital PCR.

Methods Mol Biol. 2013;949:423-31

Authors: Ramakrishnan R, Qin J, Jones RC, Weaver LS

Abstract
The Fluidigm Digital Array IFC is a nanofluidic biochip where digital PCR reactions can be performed with isolated individual DNA template molecules. This chip is part of a family of integrated fluidic circuits (IFC) and contains a network of fluid lines, NanoFlex™ valves and chambers. NanoFlex™ valves are made of an elastomeric material that deflects under pressure to create a tight seal and are used to regulate the flow of liquids in the IFC. Digital Arrays have enabled a different approach to digital PCR, by partitioning DNA molecules instead of diluting them. Single DNA molecules are randomly distributed into nanoliter volume reaction chambers and then PCR amplified in the presence of a fluorophore-containing probe. Positive fluorescent signal indicates the presence of a DNA molecule in a reaction chamber, while negative chambers are blank. IFC technology enables the delivery of very precise volumes of solutions in a simple, fast procedure, utilizing a minimum of sample and assay reagents. The development of the IFC technology and the Digital Array chip has revolutionized the field of biology, and has been utilized in gene copy number studies, absolute quantitation (molecule counting) of genomic DNA and cDNA, rare mutation detection, and digital haplotyping.

PMID: 23329458 [PubMed - in process]