Jason Niehaus

Jason is a Senior Scientist at Addgene. He received his PhD in Pharmacology from the Medical College of Georgia and previously worked in neuroscience labs studying drugs of abuse. He enjoys melding molecular biology and computing to facilitate the sharing of science.

Recent Posts

Plasmids 101: Stringent Regulation of Replication

Posted by Jason Niehaus on Dec 3, 2015 10:30:00 AM

Plasmids utilize their host cell's replication machinery in order to replicate. As described in our previous Origin of Replication post, DNA replication is initiated at the ORI and may be synchronized with the replication of the host cell's chromosomal DNA or may be independent of the host's cell cycle. 

Plasmids are said to be under stringent control of replication when they are dependent on the presence of initiation proteins synthesized by the host cell in order to start their own replication. In general, these types of plasmids tend to be low copy number. Conversely, plasmids that can initiate DNA replication independently of the host's initiation proteins are said to be under relaxed control, as they only require the host's replication machinery for elongation and termination. These types of plasmids tend to be high copy number.

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Topics: Plasmid Elements, Plasmids 101

Plasmids 101: Luciferase

Posted by Jason Niehaus on Jun 24, 2014 11:59:00 AM

Luciferases are a class of enzymes capable of catalyzing chemical reactions in living organisms resulting in the emission of photons. The most familiar bioluminescent organism for most people is the firefly (Photinus pyralis) and perhaps not surprisingly it is also the most commonly used bioluminescent reporter. This beetle emits a yellow-green light with a peak emission at 560nm. Shortly after the initial article describing the cloning of firefly luciferase was published in 1985, several studies utilized luciferase as a genetic reporter in plant and mammalian cells. Luciferase assays have since become a gold standard in gene expression analysis and a luciferase gene (one of many available to choose from) is now a common feature in reporter plasmids. 

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Topics: Plasmid Technology, Plasmids 101

Tips for Using BLAST to Verify Plasmids

Posted by Jason Niehaus on May 29, 2014 9:29:57 AM

At Addgene, we continually use the Basic Local Alignment Search Tool (BLAST) provided by NCBI. BLAST helps us compare the sequencing results of the plasmids in our repository with known reference sequences, such as full plasmid sequences provided by the laboratories that deposit their plasmids with us or other entries in NCBI’s numerous databases.

As our repository has grown over the years (we now have over 33,000 plasmids!), the number of sequencing results we analyze as part of our quality control process has steadily grown. On a busy week, we may need to analyze more than 100 sequences each day as part of our quality control process. Consequently our team has refined our use of the BLAST web browser interface as efficiently as possible.

If you find yourself frequently on the BLAST website to verify plasmids or validating your new clones, try these tips to make the most of your time and sequence!

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Topics: Plasmid How To, Lab Tips

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