Biology subjects

Ceze, L. H.

Publications and source records attributed to Ceze, L. H..

6 recordsLinked to original sources

bioRxiv2022

Doctoring Direct-to-Consumer Genetic Tests with DNA Spike-Ins

Direct-to-consumer (DTC) genetic testing companies have provided personal genotyping services to millions of customers. Customers mail saliva samples to DTC service providers to have their genotypes analyzed and receive back their raw genetic data. Both consumers and the DTC companies use the results to perform ancestry analyses, relative matching, trait prediction, and estimate predisposition to disease, often relying on genetic databases composed of the data from millions of other DTC-genotyped individuals. While the digital integrity risks to this type of data have been explored, we considered whether data integrity issues could manifest upstream of data generation through physical manipulation of DNA samples themselves, for example by adding synthetic DNA to a saliva sample ("spiked samples") prior to sample processing by a DTC company. Here, we investigated the feasibility of this scenario within the standard DTC genetic testing pipeline. Starting with the purchase of off-the-shelf DTC genetic testing kits, we found that synthetic DNA can be used to precisely manipulate the results of saliva samples genotyped by a popular DTC genetic testing service and that this method can be used to modify arbitrary single nucleotide polymorphisms (SNPs) in multiplex to create customized doctored genetic profiles. This capability has implications for the use of DTC-generated results and the outcomes of their downstream analyses.

genetics↗

bioRxiv2021

A Combinatorial PCR Method for Efficient, Selective Oligo Retrieval from Complex Oligo Pools

With the rapidly decreasing cost of array-based oligo synthesis, large-scale oligo pools offer significant benefits for advanced applications, including gene synthesis, CRISPR-based gene editing, and DNA data storage. Selectively retrieving specific oligos from these complex pools traditionally uses Polymerase Chain Reaction (PCR), in which any selected oligos are exponentially amplified to quickly outnumber non-selected ones. In this case, the number of orthogonal PCR primers is limited due to interactions between them. This lack of specificity presents a serious challenge, particularly for DNA data storage, where the size of an oligo pool (i.e., a DNA database) is orders of magnitude larger than it is for other applications. Although a nested file address system was recently developed to increase the number of accessible files for DNA storage, it requires a more complicated lab protocol and more expensive reagents to achieve high specificity. Instead, we developed a new combinatorial PCR method that outperforms prior work without compromising the fidelity of retrieved material or complicating wet lab processes. Our method quadratically increases the number of accessible oligos while maintaining high specificity. In experiments, we accessed three arbitrarily chosen files from a DNA prototype database that contained 81 different files. Initially comprising only 1% of the original database, the selected files were enriched to over 99.9% using our combinatorial primer method. Our method thus provides a viable path for scaling up DNA data storage systems and has broader utility whenever scientists need access to a specific target oligo and can design their own primer regions.

synthetic biology↗

bioRxiv2020

A Comprehensive Study of Synthetic DNA Preservation for DNA Data Storage

Synthetic DNA has recently risen as a viable alternative for long-term digital data storage. To ensure that information is safely recovered after storage, it is essential to appropriately preserve the physical DNA molecules encoding the data. While preservation of biological DNA has been studied previously, synthetic DNA differs in that it is typically much shorter in length, it has different sequence profiles with fewer, if any, repeats (or homopolymers), and it has different contaminants. In this paper we evaluate nine different methods used to preserve data files encoded in synthetic DNA by accelerated aging of nearly 29,000 DNA sequences. In addition to a molecular count comparison, we also sequence and analyze the DNA after aging. Our findings show that errors and erasures are stochastic and show no practical distribution difference between preservation methods. Finally, we compare the physical density of these methods and provide a stability versus density trade-offs discussion.

synthetic biology↗

bioRxiv2020

Content-Based Similarity Search in Large-Scale DNA Data Storage Systems

Synthetic DNA has the potential to store the worlds continuously growing amount of data in an extremely dense and durable medium. Current proposals for DNA-based digital storage systems include the ability to retrieve individual files by their unique identifier, but not by their content. Here, we demonstrate content-based retrieval from a DNA database by learning a mapping from images to DNA sequences such that an encoded query image will retrieve visually similar images from the database via DNA hybridization. We encoded and synthesized a database of 1.6 million images and queried it with a variety of images, showing that each query retrieves a sample of the database containing visually similar images are retrieved at a rate much greater than chance. We compare our results with several algorithms for similarity search in electronic systems, and demonstrate that our molecular approach is competitive with state-of-the-art electronics. One Sentence SummaryLearned encodings enable content-based image similarity search from a database of 1.6 million images encoded in synthetic DNA.

bioengineering↗

bioRxiv2020

Porcupine: Rapid and robust tagging of physical objects using nanopore-orthogonal DNA strands

Molecular tagging is an approach to labeling physical objects using DNA or other molecules that can be used in cases where methods like RFID tags and QR codes are not suitable. No molecular tagging method exists that is inexpensive, fast and reliable to decode, and usable outside a lab setting to create or read tags. To address this, we present Porcupine, an end-user molecular tagging system that features DNA-based tags readable within seconds using a portable nanopore device. Porcupines digital bits are represented by the presence or absence of distinct, nanopore-orthogonal DNA strands, which we call molecular bits (molbits). We classify molbits directly from the raw nanopore signal, avoiding basecalling. To extend the tags shelf life, decrease readout time, and make tags robust to environmental contamination, molbits are prepared for readout during tag assembly and can be stabilized by dehydration. The result is an extensible, real time, high accuracy tagging system that includes a novel approach to developing nanopore-orthogonal barcodes. One sentence summaryPorcupine lets end-users label physical objects with custom DNA tags, without requiring a lab to create or read tags, and offers rapid readout using nanopore sequencing.

synthetic biology↗

bioRxiv2018

Demonstration of End-to-End Automation of DNA Data Storage

We developed a complete end-to-end DNA data storage device. The device enables the encoding of data, which is then written to a DNA oligonucleotide using a custom DNA synthesizer, pooled for liquid storage, and read using a nanopore sequencer and a novel, minimal preparation protocol. We demonstrate an automated 5-byte write, store, and read cycle with the ability to expand as new technology is available.

synthetic biology↗