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We talk a lot about sharing data, but sharing materials is another important component of collaborative science. In this guest post, Dr Joanne Kamens of plasmid repository Addgene tells us what the most often shared plasmids are.

Are you plasmid sharing these days?  Addgene is a nonprofit plasmid repository helping scientists share plasmids internationally.  Our mission is to “Accelerate research and discovery by improving access to useful research materials and information.”

Addgene receives plasmid deposits, performs the quality control, stores the data, banks the plasmids and archives back-up stocks, for free.  Requested plasmids are then shipped to scientists for $65 USD per sample.  Scientists in over 5,000 institutions in 78 countries are sharing plasmids through our service.

In 2014, we are celebrating Addgene’s 10^th anniversary so it seems like a good time to take stock of what we have built.   We have stored over 30,000 diverse plasmids and have now distributed almost 400,000 plasmids to scientists in 78 countries.  These distribution data have given us a unique perspective on research trends in molecular biology.

Earlier this year we shared a list of the most requested plasmid in each year of Addgene’s history.  Over 800 plasmids in our collection have been distributed over 100 times.  There is amazing diversity in the fields of research covered in these 800 plasmids.  To get a sense of popular research technologies, let’s take a look at our top 25 requested plasmids of all time, listed in the order in which they became available through our service.

 

Plasmid	Depositor	Purpose	Technology	Addgene #
pBABE-puro	Robert Weinberg	Mammalian expression vector	Retroviral Expression	1764
pCMV-VSV-G	Robert Weinberg	Express VSV-G envelope	Lentiviral Expression	8454
pCMV-dR8.2 dvpr	Robert Weinberg	Lentiviral packaging	Lentiviral Expression	8455
pLKO.1 – TRC cloning vector	David Root	Express shRNA sequences	Lentiviral RNAi	10878
scramble shRNA	David Sabatini	Lentiviral negative control; scrambled shRNA	Lentiviral  RNAi	1864
pRK793	David Waugh	Express TEV protease, S219V	Protein Purification	8827
pLVTHM	Didier Trono	Express shRNA; H1 promoter	Lentiviral RNAi	12247
pMDLg/pRRE	Didier Trono	Lentiviral packaging; Gag & Pol	Lentiviral Expression	12251
pRSV-Rev	Didier Trono	Lentiviral packaging; Rev	Lentiviral Expression	12253
pMD2.G	Didier Trono	Express VSV-G envelope	Lentiviral Expression	12259
psPAX2	Didier Trono	Lentiviral packaging	Lentiviral Expression	12260
pLVCT-tTR-KRAB	Patrick Aebischer	Tet-regulated expression transgene OR shRNA	Lentiviral/RNAi	11643
M50 Super 8x TOPFlash	Randall Moon	Beta-catenin luciferase reporter	Luciferase Reporter	12456
M51 Super 8x FOPFlash (TOPFlash mutant)	Randall Moon	Beta-catenin reporter control	Luciferase Reporter	12457
pCAG-ERT2CreERT2	Connie Cepko	Express conditionally active Cre recombinase	Mammalian Expression/Cre-Lox	13777
pMXs-hKLF4	Shinya Yamanaka	Express human KLF4	IPS Cells	17219
pMXs-hc-MYC	Shinya Yamanaka	Express human cMYC	IPS Cells	17220
Tet-pLKO-puro	Dmitri Wiederschain	Inducible expression of shRNA	Lentiviral RNAi	21915
Golden Gate TALEN and TAL effector kit	Daniel Voytas	Kit to assemble TALEN constructs	TALENs	1000000016
gRNA_Cloning Vector	George Church	Empty gRNA expression vector	CRISPR/Cas9	41824
hCas9	George Church	Human codon optimized Cas9 expression	CRISPR/Cas9	41815
hCas9_D10A	George Church	Human codon optimized Cas9 D10A mutant nickase	CRISPR/Cas9	41816
pX330-U6-Chimeric_BB-CBh-hSpCas9	Feng Zhang	Human codon-optimized SpCas9 & chimeric gRNA expression	CRISPR/Cas9	42230
pX335-U6-Chimeric_BB-CBh-hSpCas9n(D10A)	Feng Zhang	Human codon-optimized SpCas9 nickase & chimeric gRNA expression	CRISPR/Cas9	42335
pX260-U6-DR-BB-DR-Cbh-NLS-hSpCas9-NLS-H1-shorttracr-PGK-puro	Feng Zhang	human codon-optimized SpCas9, a tracrRNA & customizable crRNA.	CRISPR/Cas9	42229

 

• Many of our most popular plasmids fall into the category of molecular biology “tools” that can be used by scientists in diverse fields to express proteins or probe their function.
• High demand for good lentiviral vectors was indicative of the widespread use of this technology in the early years of Addgene’s history. These systems continue to be some of our most requested reagents.
• shRNA expressing plasmids began to make an appearance early in our history and remained popular even with the easy availability of synthetic siRNA for cellular studies.  It will be interesting to see if this trend continues now that the CRISPR/Cas9 technology is available.
• 2008 saw a surge in popularity of plasmids for the study of Inducible Pluripotent Stem (IPS) Cells mirroring a rapid increase in publications in this fast-moving field.
• Other popular technologies represented in the list include luciferase reporters, cre-lox recombination systems, and tet regulated promoters.
• Late comers to the library are the tools for TALEN and CRISPR/Cas9 genome engineering experiments.  TALENs were introduced in 2011 and the first CRISPR/Cas9 plasmids went online in 2013.  Their popularity has been so high that plasmids for these relatively new technologies rocketed to the top 25 in just 1-2 years.

Addgene would like to thank all of its depositors.  Their willingness to share has allowed dissemination of their materials all over the world, making it easier for thousands of labs to design and conduct experiments that move research forward.