Microfluidic-aided genotyping of zebrafish in the first 48 h with 100% viability.

This paper introduces an innovative method for genotyping 1-2 days old zebrafish embryos, without sacrificing the life/health of the embryos. The method utilizes microfluidic technology to extract and collect a small amount of genetic material from the chorionic fluid or fin tissue of the embryo. Then, using conventional DNA extraction, PCR amplification, and high resolution melt analysis with fluorescent DNA detection techniques, the embryo is genotyped. The chorionic fluid approach was successful 78% of the time while the fin clipping method was successful 100% of the time. Chorionic fluid was shown to only contain DNA from the embryo and not from the mother. These results suggest a novel method to genotype zebrafish embryos that can facilitate high-throughput screening, while maintaining 100% viability of the embryo.

Activation of NFAT by HGF and IGF-1 via ARF6 and its effector ASAP1 promotes uveal melanoma metastasis.

Preventing or effectively treating metastatic uveal melanoma (UM) is critical because it occurs in about half of patients and confers a very poor prognosis. There is emerging evidence that hepatocyte growth factor (HGF) and insulin-like growth factor 1 (IGF-1) promote metastasis and contribute to the striking metastatic hepatotropism observed in UM metastasis. However, the molecular mechanisms by which HGF and IGF-1 promote UM liver metastasis have not been elucidated. ASAP1, which acts as an effector for the small GTPase ARF6, is highly expressed in the subset of uveal melanomas most likely to metastasize. Here, we found that HGF and IGF-1 hyperactivate ARF6, leading to its interaction with ASAP1, which then acts as an effector to induce nuclear localization and transcriptional activity of NFAT1. Inhibition of any component of this pathway impairs cellular invasiveness. Additionally, knocking down ASAP1 or inhibiting NFAT signaling reduces metastasis in a xenograft mouse model of UM. The discovery of this signaling pathway represents not only an advancement in our understanding of the biology of uveal melanoma metastasis but also identifies a novel pathway that could be targeted to treat or prevent metastatic uveal melanoma.

A rapid and efficient method of genotyping zebrafish mutants.

In order to facilitate high throughput genotyping of zebrafish, we have developed a novel technique that uses High Resolution Melting Analysis (HRMA) to distinguish wild-type, heterozygous mutants and homogyzous mutants. This one hour technique removes the need for restriction enzymes and agarose gels. The generated melting curve profiles are sensitive enough to detect non-specific PCR products. We have been able to reliably genotype three classes of mutations in zebrafish, including point mutants, apc(hu745) (apc(mcr)), and p53(zy7) (p53(I166T)), a small deletion mutant (bap28(y75)) and a retroviral insertion mutant (wdr43(hi821a)). This technique can genotype individual zebrafish embryos and adults (by tail-clip) and is applicable to other model organisms.

Spatial DNA melting analysis for genotyping and variant scanning.

A continuous-flow, temperature gradient microfluidic device was used to demonstrate spatial DNA melting analysis with the resolution and reproducibility necessary for clinical SNP scanning and genotyping of human genomic DNA. With a steady-state temperature gradient of 20-30 degrees C across a sample, melting curves were constructed from a single fluorescence data acquisition. This technique was used to scan for heterozygotes and to fully genotype single base changes using unlabeled probes. Signal-to-noise ratios of 150-300 were achieved. The thermal effects of sample flow were examined, and temperature control was aided by inclusion of an isothermal channel inlet and thermal relaxation times in the experimental protocol. Human single base variants examined by spatial DNA melting analysis included rs354439, HTR2A 102T > C, and three alleles that affect appropriate warfarin dosage (CYP2C9*2, CYP2C9*3, and VKORC1 1173C > T). Heterozygote scanning was demonstrated with rs354439, while the other PCR targets were genotyped using unlabeled probes with T(m) differences of approximately 5 degrees C between genotypes. To validate the method, 12 blinded DNA samples were genotyped at the three warfarin-related sites by spatial DNA melting analysis with 100% accuracy.