BACPAC Resources has established
a library screening service to assist end-users with identifying
BAC clones from our collection of >100 genomic libraries.
Primary screens are performed via hybridization using synthetic
oligonucleotide probes (an Overgo). The overgo probe is generated
by ordering 24-mers containing an 8 base pair overlap. The
probe is made radioactive in a fill-in reaction containing
32P-dATP, 32P-dCTP (Mc
Pherson et al.). The resulting probe is a highly specific
40mer after denaturation and inclusion in a hybridization
reaction to 22x22cm nylon filters
containing BAC clones spotted in duplicate. Each nylon filter
contains the contents of 48 microtiter dishes X 384 wells/dish
totaling 18,432 clones spotted in duplicate.
Quotes provide end-users
with an estimate for cost associated with a screening project;
all quotes are valid for 30 days. BACPAC Resources assumes
the financial liability for unsuccessful screening projects
consequently end-users are billed on a cost recovery basis.
End-users only pay for successful probes that identify probe-positive
BACs verified in the secondary PCR confirmation assay.
Library screening service*
|Option I: per gene
|BAC-library screening basic charge
including two bracketing probes for one genomic location.
|For each additional genomic location
including two bracketing probes for one genomic location. Additional probe pairs can be added to one
|Above service includes at least one positive
BAC per gene confirmed by PCR.**
|Option II: per region***
with one probe at every 50 kb for 1 mega-base genomic region.
|For additional mega-base region
with one probe at every 50 kb.
|Above service includes a set of BACs with positive signals
where PCR on pooled BACs confirms the region at every 150 kb. If you require identified
BACs by PCR or BAC-end sequencing, refer the below table.
BAC clone charge and optional service
|BAC clone charge
|Single BAC clone - verified by PCR.
|Indexed single BAC clone -
where both ends have been sequenced for mapping purposes (BAC-end sequencing).
|miniprep BAC DNA
(>1 ug of crude DNA, suitable for PCR, E.coli
transformation and restriction digestion analyses)
|midiprep BAC DNA
(>50 ug of high-quality DNA, suitable for transfection)
|Size check of BACs
determined by NotI (insert size) and PI-SceI
(linearization) restriction digestion followed by gel electrophoresis (flat
price up to 10 BAC clones).
|Charge for each package
|Domestic (additional charge applied for larger packages)
|International (additional charge applied for larger packages)
|The genomic resources will be shipped by Federal Express
or DHL/Airborne Express on either recipient's or BACPAC's account.
Prices are subject
to change without prior notification
Filters are available only as complete library sets or segments at $200
per membrane (https://bacpacresources.org/filtersAvail.php).
* The price is estimated according to typical mammalian libraries with
240-480 plates of 384-well microtiter dishes. Libraries outside of the
typical rang of plates will be quoted individually.
** All positive clones by hybridization and gene-specific PCR will be
included. A limited number of BAC libraries (such as CHORI-216, CHORI-219,
CHORI-303 constructed from the genomes of Xenopus tropicalis, Xenopus
laevis, and Sea Lamprey respectively and others) are subject to a
non-refundable set-up fee of 50% of the quoted price, if the screening does
not provide any positive signals for those libraries.
*** Large-scale screening of above 5 Mb will be quoted individually.
Information / Probe Design / Secondary Screening
provide the following: (1) the library name requested for
screening, (2) an accession number for the target sequence,
(3) and information describing the region within the target
sequence for the probe design e.g.
RPCI22 Mouse BAC Library
description: myosin, heavy polypeptide
6, cardiac muscle, alpha (Myh6)
target a region 5kb upstream of Exon 4,
and 5kb downstream of Exon 5
DNA sequence within the target region is analyzed using a
probe design script; optimal probes sequences are checked
for target specificity using bioinformatics tools on The UCSC
Genome website (http://genome.ucsc.edu).
Overgos that hybridize to the target sequence, are in conserved
regions of the genome, and don't contain repeat sequences
are optimal probes.
are verified via PCR therefore oligos required for the secondary
screening are ordered in conjunction with oligos for the overgo
probe. PCR primer design is included in the cost for the screening
consequently primers sequences are not required from the end-user.
However if an end-users has PCR primers previous verified
to generate a single band when tested using total genomic
DNA and the primers are within 5-10kb of the target sequence
please include the sequences.
receive a quote containing relevant information on the library
requested for screening, the gene target and cost for the
screening; a Payment Request Form is also included with the
quote. Once the quote has been accepted and the Payment Request
Form returned the project begins. Required information for
inclusion into the quote:
| Frequently Asked Questions
does 10X genome equivalents mean (haploid genome)?
redundancy is calculated as follows: Clones insert size (kb)
x number of clones / size of the genome (kb); the depth of
the library. A 10X redundant library contains 99% of the DNA
sequences in the genome. On average 10 BAC clones are expected
to contain the target DNA sequence in a 10X library; 5 clones
long does the library screening take after submission of the
library screening process takes 4-6 weeks on average for completion.
Laboratory closure during Institutional Holidays can affect
the timelines for project completion.
vectors for making gene knockout constructs and vectors that
facilitate BAC-end sequencing are actively being pursed in
our laboratory. The BACPAC Resource Center has and will continue
to explore methodologies utilizing BACs for downstream applications.
BACPAC Resource Center is a non-profit organization dedicated
to generating and making recombinant clone library resources
available to the scientific community. Screening high-density
colony filters is an experimental endeavor added to the list
of services intended to aid researcher with the identification
of BAC clones for downstream analysis.
used to screen recombinant clone libraries are robust and
well documented. However some DNA sequences can be problematic
posing difficulties for overgo probe design and colony hybridization.
The BACPAC Resource Center will make a good faith effort to
start and complete all services on time and will notify end-users
if unforeseen problems are likely to cause substantial delays.
BACPAC Resource Center does not guarantee that the received
clones are compatible with all down-stream applications.
BACPAC Resource Center does not guarantee that the clones
in each well are a homogeneous population. We know that a
limited amount of well-to-well cross-contamination occurs
and is unavoidable when handling arrayed libraries.
BACPAC Resource Center reserves the right to discontinue service
for probes and/or problematic DNA sequences. If it is deemed
necessary to discontinue the library screening there will
be no charge to the end-user.
BACPAC Resource Center nor the end-users shall be responsible
for failure or delay in performance of its obligations related
to the services due to causes beyond its reasonable control,
included but not limited to governmental actions, fire, labor
difficulty, shortages, civil disturbances, transportation
problems, interruptions of power or communications, failure
of suppliers, or natural disasters.
For more information,
please send inquiries to libraryScreening@chori.org