FastFISH: technique for ultrarapid fluorescence in situ hybridization on uncultured amniocytes yielding results within 2 h of amniocentesis

Cell surface polysaccharides of Bifidobacterium bifidum induce the generation of Foxp3+ regulatory T cells

Dysregulation of intestinal microflora is linked to inflammatory disorders associated with compromised immunosuppressive functions of Foxp3⁺ T regulatory (T_reg) cells. Although mucosa-associated commensal microbiota has been implicated in T_reg generation, molecular identities of the "effector" components controlling this process remain largely unknown. Here, we have defined Bifidobacterium bifidum as a potent inducer of Foxp3⁺ T_reg cells with diverse T cell receptor specificity to dietary antigens, commensal bacteria, and B. bifidum itself. Cell surface β-glucan/galactan (CSGG) polysaccharides of B. bifidum were identified as key components responsible for T_reg induction. CSGG efficiently recapitulated the activity of whole bacteria and acted via regulatory dendritic cells through a partially Toll-like receptor 2-mediated mechanism. T_reg cells induced by B. bifidum or purified CSGG display stable and robust suppressive capacity toward experimental colitis. By identifying CSGG as a functional component of T_reg-inducing bacteria, our studies highlight the immunomodulatory potential of CSGG and CSGG-producing microbes.

Camptothecin-induced expression of programmed cell death gene 11 in Spodoptera litura

BACKGROUND

Camptothecin, one of the main active components of extract from the bark of the Chinese camptotheca tree, has been reported as a potent insecticide against various insect species. However, the mechanism of action of camptothecin as a botanical pesticide is not completely understood.

RESULTS

In this study, the full-length cDNA (GeneBank number JF681972) of Spodoptera litura programmed cell death protein 11 (pcdp 11) isoform 1 was cloned, sequenced and characterised. Quantitative real-time PCR (qRT-PCR) data showed that pcdp 11 was differentially expressed during the developmental stages, with significantly high expression during the transition from egg to larva and larva to pupa. Furthermore, pcdp 11 was upregulated in a time-dependent manner in SL-1 cells after treatment with 1.2 µg mL(-1) of camptothecin. The induced expression profile of pcdp 11 in the larval midgut after feeding camptothecin was visualised by fluorescence in situ hybridisation (FISH) and further quantified by qRT-PCR. Apoptosis in camptothecin-treated larval midguts was confirmed using terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining.

CONCLUSION

The results reveal a clear functional link between pcdp 11 expression and camptothecin-induced apoptosis, and prove that camptothecin exhibits strong toxicity towards S. litura by inducing midgut epithelial cell apoptosis.

Rapid-prenatal diagnosis through fluorescence in situ hybridization for preventing aneuploidy related birth defects

BACKGROUND AND OBJECTIVE:

Women with high-risk pregnancies are offered prenatal diagnosis through amniocentesis for cytogenetic analysis of fetal cells. The aim of this study was to evaluate the effectiveness of the rapid fluorescence in situ hybridization (FISH) technique for detecting numerical aberrations of chromosomes 13, 21, 18, X and Y in high-risk pregnancies in an Indian scenario.

MATERIALS AND METHODS:

A total of 163 samples were received for a FISH and/or a full karyotype for prenatal diagnosis from high-risk pregnancies. In 116 samples both conventional culture techniques for getting karyotype through G-banding techniques were applied in conjunction to FISH test using the AneuVysion kit (Abbott Molecular, Inc.), following standard recommended protocol to compare the both the techniques in our setup.

RESULTS:

Out of 116 patients, we got 96 normal for the five major chromosome abnormality and seven patients were found to be abnormal (04 trisomy 21, 02 monosomy X, and 01 trisomy 13) and all the FISH results correlated with conventional cytogenetics. To summarize the results of total 163 patients for the major chromosomal abnormalities analyzed by both/or cytogenetics and FISH there were 140 (86%) normal, 9 (6%) cases were abnormal and another 4 (2.5%) cases were suspicious mosaic and 10 (6%) cases of culture failure. The diagnostic detection rate with FISH in 116 patients was 97.5%. There were no false-positive and false-negative autosomal or sex chromosomal results, within our established criteria for reporting FISH signals.

CONCLUSION:

Rapid FISH is a reliable and prompt method for detecting numerical chromosomal aberrations and has now been implemented as a routine diagnostic procedure for detection of fetal aneuploidy in India.

The promise of fetal cells in maternal blood

Delaying childbirth increases the proportion of advanced maternal age pregnancies. This increases the number of pregnancies requiring invasive prenatal testing. Prenatal diagnosis of chromosomal aneuploidies and monogenic disorders requires fetal cells obtained through invasive procedures (i.e. chorionic villus sampling and amniocentesis). These procedures carry a risk of fetal loss, which causes anxiety to at-risk couples. Intact fetal cells entering maternal circulation have raised the possibility of non-invasive prenatal diagnosis. Rarity of fetal cells, however, has made it challenging. Fetal nucleated red blood cells are ideal candidate target cells because they have limited lifespan, contain true representation of fetal genotype, contain specific fetal cell identifiers (embryonic and fetal globins), and allow interrogation with chromosomal fluorescence in-situ hybridisation and possibly with array comparative genomic hybridisation. The utility of fetal nucleated red blood cells in non-invasive prenatal diagnosis has not reached clinical application because of the inconsistencies in enrichment strategies and rarity of cells.

Non-invasive prenatal diagnostics using next generation sequencing: technical, legal and social challenges

INTRODUCTION

Newly developed non-invasive prenatal diagnostic techniques, using maternal blood samples, have the potential to reduce or obviate the need for invasive prenatal diagnostic practices such as amniocentesis or chorionic villous sampling. This will lead to a change in how obstetric care is extended by health care providers to pregnant women at-risk of bearing an aneuploid child.

AREAS COVERED

The process leading to the development of fetal aneuploidy detection via the analysis of cell-free DNA in maternal plasma by massive parallel sequencing. Optimization of these strategies and approaches used in the recent or up-coming commercial launches. In addition, this review provides insight into legal implications, potential patent disputes, ethical and societal concerns raised by this development, such as whole genome data storage, retrieval and access.

EXPERT OPINION

There is a need for engagement by professional societies, to ensure correct usage of these newly emerging technologies and their restriction to high-risk pregnancies. National agencies need to ensure the necessary degree of high quality required for prenatal diagnosis.

Molecular diagnosis of Down syndrome using quantitative APEX-2 microarrays

OBJECTIVE

To develop a new rapid and high-throughput microarray-based prenatal diagnostic test for the detection of trisomy 21 (T21).

METHODS

The T21 arrayed primer extension-2 (APEX-2) assay discriminates between trisomy and euploid DNA samples by comparing the signal intensities of allelic fractions of heterozygous single nucleotide polymorphisms (SNPs) after APEX reaction. After preliminary validation using DNA samples from Down syndrome patients, we analyzed DNA samples from cultured and uncultured amniocytes and chorionic villus for 90 SNPs with high heterozygosity from the 21(q21.1q22.2) region. Differences in allelic ratios of heterozygous SNPs in normal and T21 individuals were verified by t-test.

RESULTS

Analysis of the T21 APEX-2 assay results revealed that 90 SNPs were sufficient for reliable discrimination between T21 and euploid DNA samples (P≤0.05 for one or both strands). Using 134 clinical samples from cultured or uncultured fetal cells, both the sensitivity and the specificity of the assay were 100%.

CONCLUSION

Our study provides a proof of principle demonstration of the use of the modified APEX-2 assay as a new, fast and reliable method for prenatal diagnosis of fetal T21.

Prenatal diagnosis of fetal aneuploidies: post-genomic developments

Prenatal diagnosis of fetal aneuploidies and chromosomal anomalies is likely to undergo a profound change in the near future. On the one hand this is mediated by new technical developments, such as chromosomal microarrays, which allow a much more precise delineation of minute sub-microscopic chromosomal aberrancies than the classical G-band karyotype. This will be of particular interest when investigating pregnancies at risk of unexplained development delay, intellectual disability or certain forms of autism. On the other hand, great strides have been made in the non-invasive determination of fetal genetic traits, largely through the analysis of cell-free fetal nucleic acids. It is hoped that, with the assistance of cutting-edge tools such as digital PCR or next generation sequencing, the long elusive goal of non-invasive prenatal diagnosis for fetal aneuploidies can finally be attained.

FlashFISH: "same day" prenatal diagnosis of common chromosomal aneuploidies

Fluorescence in situ hybridization (FISH) and quantitative fluorescence (QF)-PCR are rapid molecular methods that test for common chromosomal aneuploidies in prenatal diagnosis. While cytogenetic analysis requires approximately 7-14 days before fetal karyotypes are available, these molecular methods release results of sex chromosome aneuploidies, Down syndrome, Edward's syndrome, and Patau's syndrome within 24-48 h of fetal sampling, alleviating parental anxiety. However, specific diagnosis or exclusion of aneuploidy should be available within the same day of amniocentesis. We developed "FlashFISH," a low cost FISH method that allows accurate results to be reported within 2 h of fetal sampling. Here, we report our experience of using FlashFISH in prenatal diagnosis, and we illustrate in detail the protocols used for the purpose in our laboratory.