Das Bacterial Two Hybrid System PDF

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Författare: Elif Köksoy.
Das Bacterial Two Hybrid System, welches 1998 von Karimova et al. entwickelt wurde ist eine einfache Methode, die in vivo Screening und Selektion funktioneller Interaktionen bakterieller Proteine ermöglicht. Das allgemeine Prinzip beruht auf der funktionellen Komplementation zweier Fragmente aus der katalytischen Domäne der Adenylatzyklase, einem Enzym, welches zyklisches AMP (cAMP) aus AMP synthetisiert. Im Fall eines funktionell intakten Enzymes bildet das synthetisierte cAMP einen Komplex mit dem sogenannten CAP-Protein aus und führt als solches zur Induktion des Laktose-Operons. Die Fragmente T18 und T25 der katalytischen Domäne liegen in zwei Vektoren vor, in welche die Sequenzen der auf Interaktion zu analysierenden Proteine kloniert werden. Eine Interaktion bringt die funktionell voneinander abhängigen Fragmente in räumliche Nähe, was zur Ausübung der Enzymfunktion ausreicht. Beim eingesetzten Klonierstamm für das BTH-System handelt es sich um E.coli BTH101, welcher Adenylatzyklase-defizient ist. Eine Komplementation des Defizites durch Protein-Interaktionen führt zur Laktose-Verwertung in den Zellen, was durch einen Farbumschlag auf Indikatormedium verfolgt werden kann. Entsprechend kann eine Aussage über putativ bestehende Interaktionen getroffen werden.

Large lower pitcher of Nepenthes rajah. Borneo, showing natural range of Nepenthes rajah highlighted in green. The species was collected by Hugh Low on Mount Kinabalu in 1858, and described the following year by Joseph Dalton Hooker, who named it after James Brooke, the first White Rajah of Sarawak. Nepenthes rajah is most famous for the giant urn-shaped traps it produces, which can grow up to 41 cm high and 20 cm wide.

These are capable of holding 3. 5 litres of water and in excess of 2. The plant is known to occasionally trap vertebrates and even small mammals, with drowned rats having been observed in the pitcher-shaped traps. Many of these animals are so specialised that they cannot survive anywhere else, and are referred to as nepenthebionts. Hybrids between it and all other Nepenthes species on Mount Kinabalu have been recorded.

However, due to the slow-growing nature of N. Joseph Dalton Hooker described Nepenthes rajah in 1859, naming it in honour of Sir James Brooke, the first White Rajah of Sarawak. Click to view a botanical description of Nepenthes rajah. Latin description: Folia mediocria petiolata, lamina oblonga v. Leaves: coriaceous, shortly petiolate, yellow to green in colour, with a wavy outer margin.

15 cm wide, rounded and peltate at the apex, rounded at the base, abruptly attenuate towards the petiole. The characteristic peltate leaf attachment of N. Nepenthes rajah, like virtually all species in the genus, is a scrambling vine. The stem usually grows along the ground, but will attempt to climb whenever it comes into contact with an object that can support it. 6 m in length, although it rarely exceeds 3 m.

Leaves are produced at regular intervals along the stem. They are connected to the stem by sheathed structures known as petioles. A long, narrow tendril emanates from the end of each leaf. They are leathery in texture with a wavy outer margin. The leaves are characteristically peltate, whereby the tendril joins the lamina on the underside, before the apex.

This characteristic is more pronounced in N. All Nepenthes pitchers share several basic characteristics. Traps consist of the main pitcher cup, which is covered by an operculum or lid that prevents rainwater from entering the pitcher and displacing or diluting its contents. Nepenthes rajah, like most species in the genus, produces two distinct types of traps. Lower“ or „terrestrial“ pitchers are the most common. These are very large, richly coloured, and ovoid in shape.