Incubation of 48,000 X g rat brain supernatants for 30 min at 37 degrees with 1-2 mM guanylyl 5'-methylenediphosphonate [Gmp(CH2)pp] results in polymerization of 95-98% of the tubulin present. This is considerably more than the 50% polymerization that can be achieved with the natural nucleotide, GTP, under optimal conditions. Gmp(CH2)pp is also much more effective than GTP in inducing polymerization of purified tubulin. Assembly of microtubules with Gmp(CH2)pp occurs at tubulin concentrations one-third of those possible with GTP. Furthermore, with Gmp(CH2)pp, microtubule assembly does not require the high molecular weight basic proteins needed with GTP. Polymerization of tubulin by Gmp(CH2)pp is neither prevented nor reversed by concentrations of calcium (2 mM) that can either prevent microtubule assembly or disrupt already formed microtubules if the nucleotide used is GTP or guanylyl imidodiphosphate. When Ca2+ is added before or after microtubule assembly, electron microscopy of the Gmp(CH2)pp preparations reveals normal microtubules turning into twisted ribbons. Low temperature (4 degrees) can both prevent and disrupt the tubulin assembled Gmp(CH2)pp although disruption proceeds much more slowly when GTP is used.

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The 630’s CE witnessed pivotal battles in the history of the ancient Near East resulting in victories of Arabic armies over the forces of the Byzantine and the Sasanian Empires. The sources that have preserved these battles portray the commanders as either heroic or villainous, as men whose decisions have turned the tide of history. Many of the details around the battles are difficult to pin down in terms of date and even location but the commanders who fought and their stories are preserved for us in the extant sources. There are both contemporary and later Islamic versions to compare and contrast. The chief Sasanian commander Rostam, and his Albanian lieutenant Juansher remain celebrated for their heroic efforts against the Arabic armies, even though they lost, while the contemporary Byzantine Armenian commander Vahan is labelled as treasonous for his defeat at/around Yarmouk. This chapter explores the identity and representation of these commanders to assess to what degree the different literary traditions allow them to be heroic or disastrous. The aim is to assess whether we can understand, in the different traditions, the way in which a good general should behave in the 7th century through the accounts of their deeds.