user manual
blotting
Hoefer PR648
Slot blot manifold
um PR648-IM/Rev.F0/08-12
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Introduction ..........................................................1
Specifications........................................................2
Procedure for standard use of
the Hoefer PR648 ................................................3
Setting up the Hoefer PR648 ............................3
Applying your samples .......................................5
Removing your blot ............................................5
Care and maintenance ...........................................6
Troubleshooting ..................................................... 7
Ordering information ..............................................8
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Introduction
Slot-and dot-blotting techniques have been used
extensively in molecular biology to immobilize
nucleic acids and proteins on membranes for
determining nucleic acid homologies, quantifying mRNA, studying hormone receptor binding,
detecting protein-nucleic acid interactions, and
screening for specific proteins by activity or
antibody. The slot-shaped blots produced by
the Hoefer® PR648 slot blot filtration manifold
are more reliably and accurately quantitated
by scanning densitometry than dot blots. For a
series of dots, the scan path must pass directly
through the center of all the dots. Slots are not
so demand ing in alignment and allow much
wider representative scan paths.
The Hoefer PR648 slot blot filtration manifold
is designed and manufactured to provide an
efficient seal around each slot insuring a consistent shape and size. As little as 50 µl of sample
applied to a membrane through the slot will
yield a clearly defined band with evenly distributed sample.
Each Hoefer PR648 slot blot is comprised of
three separate blocks. The upper block has
48 labeled slots for samples, arranged in a
4 × 12 array. The blotting membrane is placed
in a recess on the top of the middle (membrane
support) block. The bottom block has a connector for the vacuum source.
To assemble the Hoefer PR648 slot blot, simply
place the membrane in the membrane support
block recess, stack the blocks together, and
insert and tighten the screws. Attach the connector on the bottom block to a vacuum source and
apply your samples in the slots.
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Fig 1. The Hoefer PR648 slot blot
set up for standard use.
Specifications
Number of slots: 48
Slot dimensions: 6 mm × 0.80 mm
Slot spacing: 9.0 mm × 18 mm
Slot membrane surface area: 4.8 mm
Maximum well volume: 1 ml
Recess dimension: 82 mm × 115 mm
Unit dimensions: 12 cm × 15.5 cm × 8 cm
(from center to center)
2
top block
membrane
membrane recess
membrane
support block
orientation
corner
quick disconnect
bottom block
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Procedure for standard use of the Hoefer PR648
The following procedure produces a well-defined
blot with sharp edges with many types of samples.
To determine the optimal load per slot for the
particular membrane and samples you are using,
we suggest first blotting a set of serial dilutions.
Setting up the Hoefer PR648
1
Place the bottom block on the lab bench. Place the
membrane support block (middle block), with the
0-ring facing down, on top of the bottom block.
The membrane recess in the membrane support block
has one curved corner. Orient the block with this
corner on the lower right (see Fig 1).
2
Wear gloves to avoid leaving fingerprints on the
membrane. Place the membrane cutting template,
ridge side down, on the membrane. Exert slight
pressure on the template to leave a mark on the
membrane. Cut the membrane along the mark. The
template has been sized to allow for swelling of all
types of membrane.
3
Soak the membrane in appropriate buffer for a few
minutes to wet it thoroughly. (A dry membrane will
draw sample under the sealing ridge and away from
the slot, resulting in a poorly defined slot image on
the membrane.)
4
Place the membrane completely within the recess,
aligning the clipped corner of the membrane with the
clipped corner of the recess.
Make sure the membrane is flat and fits completely
within the area, with edges parallel to the recess
edges. If the membrane is not positioned correctly,
lift it up and reposition it.
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Note: Do not over-tighten.
Over-tightening causes leaks.
Fig 2. Correct order for tightening
the screws.
Fig 3. Correct set-up of the
liquid trap.
5
Carefully set the top block, with letters and numbers
facing up, on top of the membrane support block.
6
Insert the screw into the threaded holes. Tighten
the screws until the knobs just touch the surface of
the block.
7
Hand-tighten each screw only a small amount, following
the sequence shown in Fig 2. Repeat the sequence
one or two times until all screws are snug.
8
Attach the slot blot to a small vacuum pump with
adjustable vacuum and a vacuum gauge. If an adjustable vacuum pump is not available, use a water aspirator or a house vacuum and place a bleed valve and
vacuum gauge in the vacuum line.
9
To keep liquids from being sucked into the vacuum
source, set up a liquid trap between the slot blot and
the vacuum source as shown in Fig 3:
a. Use a side arm vacuum flask and a stopper with a
small hole.
b. Insert a glass tube through the stopper hole.
Position the tube so that it extends below the flask
sidearm when the stopper is in place.
c. Stopper the flask. Use a length of rubber tubing
to connect the glass tube in the stopper to the
connector on the Hoefer PR648.
d. Use a second length of tubing to connect the side-
arm of the flask to the intake port of the vacuum
pump or to the vacuum line.
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Note: Do not use samples
containing organic solvents.
Applying your samples
1
Turn on the vacuum pump and adjust the pump or
bleed valve until the vacuum is 13 –25 cm Hg.
2
Turn off the vacuum.
3
Carefully load a sample, at least 50 µl in volume, into
each well. (A 50 µl size is necessary to distribute the
sample evenly over the slot.) To prevent bubbles from
forming, pipet each sample against the bottom side-wall
of the well. This is especially important it your sample
contains proteins or detergents. If bubbles should form,
flush them out with the pipetter tip.
4
Turn on the vacuum and set it at 13 – 25 cm Hg.
When all of the sample liquid has been pulled through
the membrane, add 1 ml of buffer to each slot,
pipetting against the bottom-side wall. Adjust vacuum
to 38 – 50 cm Hg. After all of the buffer is pulled
through, repeat twice more for a total of three rinses.
Removing your blot
1
With the vacuum still on, remove the screws and
carefully lift off the top block.
2
Using forceps, lift the membrane off and place it on
clean, dry filter paper. Turn off the vacuum.
3
Process the membrane according to your protocol.
4
If you plan to scan the blot itself with a densitometer,
dry the membrane flat by placing it on the smooth
side of a porous polyethulene sheet. Dry it for several
minutes in a vacuum gel dryer without heat.
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Care and maintenance
1
If the slot blot is used with radioactive materials,
decontaminate the 0-ring between uses. You may wish
to purchase a second ring for non-radioactive work.
(See Ordering information.)
2
Wash all blocks thoroughly in a mild water-based
laboratory detergent, then rinse well in distilled water.
Brief exposure to 5% bleach solutions can be used.
Do not use ethanol or other organic solvents. Do not
autoclave the slot blot or wash it at high temperatures.
3
Blot all blots dry immediately. Acrylic can absorb
water, which may cause it to warp.
4
Store the slot blot away from direct sunlight. If you
store it assembled, do not tighten the screws.
5
Store the PR648 slot blot with the membrane cutting
template, flat side-up, between the middle and top
blocks. This will protect the sealing ridge surrounding
the slots.
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Troubleshooting
problem solution
If the sample area on the membrane is
larger than the slot size, or if the solution
is leaking out of the slot…
Screws are tightened too Carefully follow the tightening instructions in Steps 6 and 7
far or not tightened far enough. in Setting up the Hoefer PR648 slot blot.
The membrane is not positioned Make sure the membrane is flat and fits completely within
correctly with the recess. the recess with its edges parallel to the recess edges.
The membrane is dry. Before blotting, be sure to soak the membrane in buffer to
If small impressions show on the
membrane around the blot…
This is normal. The impressions, which indicate a tight seal, will not affect
If there are bubbles in the slot…
There are proteins or detergent in the To prevent bubbles from forming, be sure to pipet the sample
sample. Or, the sample was squirted slowly and carefully against the bottom side-wall of the slot.
rapidly into the slot. If necessary, flush bubbles out with a pipette tip.
wet it thoroughly.
your results if you scan the membrane in reflectance mode.
Place the membrane flat on the smooth side of a porous
polyethylene sheet, and dry it for several minutes in a gel dryer
without heat.
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Ordering information
product qty. code no.
Basic Unit
Hoefer PR648 Slot blot manifold 1 PR648
with Quick Fit connector and
membrane cutting template.
Replacement Parts for the
PR648 Slot blot
Top Block 1 PR654
Membrane support block 1 PR659
(middle block). Includes O-ring.
Bottom Block 1 PR656
O-rings 1 PR657
Screws 6 PR658
Membrane cutting template 1 PR659
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Hoefer, Inc.
84 October Hill Road
Holliston, MA 01746
Toll Free: 1-800-227-4750
Phone: 1-508-893-8999
Fax: 1-508-893-0176
E-mail: support@hoeferinc.com
Web: www.hoeferinc.com
Hoefer is a registered trademark
of Hoefer, Inc.
© 2012 Hoefer, Inc. —
All rights reserved.
Printed in the USA.
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