MIT's license for SnapGene requires that users log in from one of the following list of IP address ranges: Cisco An圜onnect client for Windows, Mac OS X and Linux.How to connect to MIT's Virtual Private Network If you are accessing SnapGene from an off campus location, you will need to connect to the MIT Virtual Private Network before launching SnapGene. MIT's license for SnapGene requires that users log in from specified MIT networks, including the MIT campus network, CSAIL, the legacy AI lab address space, Lincoln, Haystack, LNS, and the PSFC or from an MIT VPN connection. SnapGene is licensed for educational, academic and research use by the MIT community. When performing a diagnostic restriction digest of your minipreps, always include the starting vector as a reference standard.How can I login to SnapGene from an off campus location? Access SnapGene from specified MIT networks.If you obtain many more transformants for the ligation with the inserted fragment than for the control ligation, your cloning almost certainly worked, and you can usually get away with making just 3-4 minipreps.If the DNA has any blunt ends, ligate at room temperature for ~4 hr and use high-concentration T4 ligase. If the DNA has only sticky ends, ligate at room temperature for ~1 hr.coli efficiently, and re‑circularization of the vector cannot occur without ligation to a phosphorylated fragment. This control ligation should yield very few transformants because only circular DNA molecules transform E. With a phosphatase-treated vector, perform a control ligation in which the inserted fragment is omitted.If you plan to clone a blunt-ended PCR fragment (generated with a polymerase such as Pfu) into a phosphatase-treated vector, ensure that your PCR primers have 5′-phosphates. If the inserted fragment was generated by PCR, purify it with a gel or spin-column before doing any restriction digests.When visualizing DNA bands with a transilluminator, do not use short wavelength UV light of 312 nm or below because the DNA will be severely damaged. In addition to removing unwanted or incompletely digested DNA, this procedure removes enzymes and small molecules. Purify the inserted fragment with a gel.You can use relatively short digestion times, and for a double digest, you can use a reaction buffer that is suboptimal for one or both enzymes. For preparation of an inserted fragment, incomplete digestion is not a serious concern because partial recovery of the fragment is acceptable.It is a good idea to spin briefly after vortexing to ensure that no droplets are left on the side of the tube. Vortex the mixtures thoroughly and repeatedly, and do not allow any droplets of liquid to escape enzyme treatment. With the vector, ensure that the digestion and phosphatase reactions go to completion. Gel purification of the vector is usually unnecessary because phosphatase treatment will inactivate any extra DNA fragments that were generated. Remove the phosphatase with a spin-column.After digesting the vector (and blunting, if appropriate), treat with phosphatase: 1 hr at 37☌ for 5′ overhangs, or 1 hr at 50☌ if the DNA has any blunt ends or 3′ overhangs.If the vector needs to be cut with two enzymes that have different optimal reaction buffers, perform the digests sequentially, with a spin-column purification in between. Use an excess of restriction enzyme (~20 U for 2 μg DNA), and digest for ~4 hr. Ensure that digestion of the vector goes to completion.The tricks described below will minimize these effects. This problem has two causes: incomplete digestion of the vector, and re‑ligation of the cut vector with itself. The most common problem with restriction cloning is that the starting vector is recovered after the procedure. Cleaner starting material will yield a better outcome. When in doubt, purify a DNA fragment with a gel.For example, it works better to clone a blunt-ended fragment into a blunt vector site, such as a SmaI site, than into a site that has been blunted with Klenow or T4 DNA polymerase. To maximize efficiency, minimize the number of steps in a procedure.(There is no need to use a spin-column before purifying a DNA fragment with a gel.) Elute the DNA in 40 – 45 μl of 10 mM Tris (pH 8.5), and then perform the next reaction. After each enzymatic reaction, purify the DNA with a spin-column.Start with about 2 μg of DNA when preparing a vector or excising a fragment to be inserted. This approach saves time in the long run. First and foremost, be careful at each step of a procedure.A few simple tricks will help to ensure that your cloning goes smoothly. Restriction Cloning Tipsįor many applications, conventional restriction cloning is still the best method. Using a specific example, you will learn to simulate inserting a single fragment into a plasmid vector using restriction and insertion cloning in SnapGene.
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