Science (2011) Vol. 331 no pp

Javier Martinez Institute of Molecular Biotechnology Vienna, Austria Stefan Weitzer Johannes Popow Markus Englert Reinhard Lührmann

そのタンパク質が特定の活性を有する ということ： 1. タンパク質の挙動と活性の挙動が 区別されない 2. そのタンパク質に変異を入れると 該当する活性が消失する。

Transfection Transfection is the process of deliberately introducing nucleic acids into cells. The term is used notably for non-viral methods in eukaryotic cells. It may also refer to other methods and cell types, although other terms are preferred: "transformation" is more often used to describe non-viral DNA transfer in bacteria, non- animal eukaryotic cells and plant cells - a distinctive sense of transformation refers to spontaneous genetic modifications (mutations to cancerous cells (Carcinogenesis), or under stress (UV irradiation)). "Transduction" is often used to describe virus-mediated DNA transfer. The word transfection is a blend of trans- and infection. Stable and transient transfection For most applications of transfection, it is sufficient if the transfected genetic material is only transiently expressed. Since the DNA introduced in the transfection process is usually not integrated into the nuclear genome, the foreign DNA will be diluted through mitosis or degraded. If it is desired that the transfected gene actually remains in the genome of the cell and its daughter cells, a stable transfection must occur. To accomplish this, a marker gene is co- transfected, which gives the cell some selectable advantage, such as resistance towards a certain toxin. Some (very few) of the transfected cells will, by chance, have integrated the foreign genetic material into their genome. If the toxin is then added to the cell culture, only those few cells with the marker gene integrated into their genomes will be able to proliferate, while other cells will die. After applying this selective stress (selection pressure) for some time, only the cells with a stable transfection remain and can be cultivated further.

Ribonuclease T1 (sometimes abbreviated RNase T1) is a fungal endonuclease that cleaves single-stranded RNA after guanine residues. RNase T2 is sequence specific for single- stranded RNAs. It cleaves 3'-end of all 4 residues, but preferentially 3'-end of As.

薄層クロマトグラフ法 (thin layer chromatography (TLC))

ゲルろ過クロマトグラフィーの溶出パターン（クロマトグラム）の一例を図に 示しました。担体ポア内に入り込まない大きな分子はバッファーと同じ速度で カラムを通過するので排除体積（ V0 ）またはその直後に溶出されます。適切に 充填されたカラムの排除体積はおよそベッド体積の 30 ％になります。担体内に 入りこめる分子は大きいものから順に溶出されます（ Technical Tips vol.23 をご参 照ください）。塩などの小さな分子は 1 カラム体積（ Vt ）のバッファーがカラム を通過する直前に溶出されます。