Mary Gearing

Mary Gearing is a Scientist at Addgene. She got her start as a Science Communications Intern writing for the Addgene blog and website. As a full-time Addgenie, she still enjoys blogging about CRISPR and other cool plasmids!

Recent Posts

CRISPR 101: Editing the Epigenome

Posted by Mary Gearing on Feb 14, 2017 10:44:08 AM

Epigenetic modifications are an additional layer of control over gene expression that go beyond genomic sequence. Dysregulation of the epigenome (the sum of epigenetic modifications across the genome) has been implicated in disease states, and targeting the epigenome may make certain processes, like cellular reprogramming of iPSCs, more efficient. In general, epigenetic chromatin modifications are correlated with alterations in gene expression, but causality and mechanisms remain unclear. Today, targeted epigenetic modification at specific genomic loci is possible using CRISPR, and Addgene has a number of tools for this purpose!

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Topics: CRISPR, CRISPR 101

Single Base Editing with CRISPR

Posted by Mary Gearing on Aug 16, 2016 10:30:00 AM

When we talk about CRISPR applications, one negative always comes up: the low editing efficiency of homology-directed repair (HDR). Compared to the random process of non-homologous end joining, HDR occurs at a relatively low frequency, and in nondividing cells, this pathway is further downregulated. Like all CRISPR applications that use wild-type Cas9, editing by HDR also has some potential for off-target cleavage even when gRNAs are well designed. Rather than try to improve HDR, Addgene depositor David Liu’s lab created new Cas9 fusion proteins that act as “single base editors.” These fusions contain dCas9 or Cas9 nickase and the rat cytidine deaminase APOBEC1, which can convert cytosine to uracil without cutting DNA. Uracil is subsequently converted to thymine through DNA replication or repair. Komor et al. estimate that hundreds of genetic diseases could be good targets for base editing therapy, not to mention the potential basic and preclinical research applications. Read on to learn about this new way to make point mutations using CRISPR without double-stranded breaks.

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Topics: Genome Engineering, CRISPR

Cpf1 Update: Comparison to Cas9 and NgAgo

Posted by Mary Gearing on Jul 14, 2016 10:30:00 AM

In 2015, Feng Zhang’s lab characterized two Cpf1 nucleases, distant cousins of well-known Cas9. Cpf1 cleaves DNA in a staggered pattern and requires only one RNA rather than the two (tracrRNA and crRNA) needed by Cas9 for cleavage. Now, two new studies show that Cpf1 displays lower off-target editing than Cas9, confirming that this protein is well suited for genome editing. 

Find Cpf1 Plasmids at Addgene

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Topics: Genome Engineering, CRISPR

Comparing Cas9 to NgAgo: Can the Argonautes Best CRISPR?

Posted by Mary Gearing on Jun 9, 2016 10:30:00 AM

Biologists are going gaga over the newest gene-editing protein - a DNA-cleaving Argonaute from Natronobacterium gregoryi, or NgAgo for short. Addgene has already distributed this plasmid all over the world, and the question on everyone’s minds is: could NgAgo replace CRISPR? Such a drastic shift won’t happen overnight, but there are a few reasons why you might choose NgAgo over CRISPR proteins Cas9 or Cpf1 - keep reading to learn more!

Find New Tips in the Han Lab's NgAgo Protocol Here!

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Topics: Plasmid Technology, Genome Engineering, CRISPR

Lentiviral Vector Uses and Overview

Posted by Mary Gearing on May 19, 2016 10:30:00 AM


Lentiviral vectors
are one of the most popular and useful viral vectors in the lab. Advantages of lentivirus include a large genetic capacity and the ability to transduce both dividing and non-dividing cells. Lentiviral vectors are the vector of choice for many CRISPR applications, and they’ve also had success in clinical gene therapy applications. Read on to learn more about the current (and future) applications of lentiviral vectors!

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Topics: Viral Vectors

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