Abstract Background Biological nitrogen fixation is catalyzed by Mo-, V- and Fe-nitrogenases that are encoded nif , vnf anf genes, respectively. NifB the key protein in synthesis of cofactors all nitrogenases. Most diazotrophic Paenibacillus strains have only one nifB gene located a compact cluster ( nifBHDKENX orf1 ) hesAnifV ). But some multiple genes their functions not known. Results A tota...

Automata on infinite words (ω-automata) have wide applications in formal language theory as well as in modeling and verifying reactive systems. Complementation of ωautomata is a crucial instrument in many these applications, and hence there have been great interests in determining the state complexity of the complementation problem. However, obtaining nontrivial lower bounds has been difficult....

We study the problem of closure under complementation of languages accepted by one-way and two-way tree automata modulo equational theories. We deal with the equational theories of commutative monoids ( ), idempotent commutative monoids ( ), Abelian groups ( ), and the theories of exclusive-or ( ), generalized exclusive-or ( ), and distributive minus symbol ( ). While the one-way automata for a...

The only demonstrated mechanism for intracistronic genetic complementation requires physical interaction of protein subunits to create a functional molecule. We demonstrate another and perhaps quite general mechanism utilizing proteins with unique and shared domains. The Drosophila neural mutant Passover (Pas) disrupts specific synaptic connections. Alleles of a lethal complementation group exh...

Fusion between HeLa and fibroblasts from complementation group D xeroderma pigmentosum (XPD) followed by challenge with small doses of ultraviolet light (u.v.) results in the production of hybrid cells expressing either HeLa (HD1) or XPD-like (HD2) sensitivity to u.v. and related repair capacity. Assays used included unscheduled DNA synthesis (UDS), DNA break accumulation in the presence of inh...