No abstract

The Bm86 antigen, as originally identified in Boophilus microplus, is the basis of commercial tick vaccines against this tick species. The potential for using this antigen or homologues of the antigen in vaccination against other tick species has been assessed. We have conducted vaccine trials in cattle using the B. microplus-derived recombinant Bm86 vaccine (TickGARD) using pairs of vaccinated calves and control calves. These were infested with B. microplus and Boophilus decoloratus larvae simultaneously. For both species, the numbers of engorged female adult ticks, their weight and egg-laying capacity were all reduced, leading to a reduction in reproductive capacity of 74% for B. microplus and 70% for B. decoloratus. Hyalomma anatolicum anatolicum ticks were fed both as immatures as well as adults on vaccinated calves and non-vaccinated controls. There was an overall 50% reduction in the total weight of nymphs engorging on vaccinated calves, and a suggestion of a subsequent effect on feeding adults. For Hyalomma dromedarii there was a 95% reduction in the number of nymphs engorging and a further 55% reduction in weight of those ticks surviving. Rhipicephalus appendiculatus and Amblyomma variegatum ticks were fed simultaneously both as immatures and subsequently as adults. There was no evidence for a significant vaccination effect. Finally, the amino acid sequence of a Bm86 homologue found in H. a. anatolicum unequivocally demonstrated the conservation of this molecule in this species. Our strategy for the development of multivalent anti-tick vaccines is discussed in relation to these findings.

Several metalloenzymes, including [FeFe]-hydrogenase, employ cofactors wherein multiple metal atoms work together with surrounding ligands that mediate heterolytic and concerted proton-electron transfer (CPET) bond activation steps. Herein, we report a...

Structural modification of the tetrahydroisoquinoline (THIQ) framework is of significant interest to organic chemists due to its central role in heterocyclic and medicinal chemistry. Here we demonstrate an efficient metal-free method for the oxidative functionalization of THIQs at the C1 position, which is amenable to a diverse range of C-C coupling reactions. These reactions proceed through a hydride abstraction involving the tropylium ion followed by quenching the generated iminium intermediates with nucleophiles to afford THIQ derivatives with excellent efficiencies and interesting selectivities.

Homogeneous electrocatalytic proton reduction is reported using cobalt complex [1](BF 4) 2 .T his complex comprises two bis(1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methane (HBMIM Ph 2)l igandst hat contain an acidic methylene moiety in their backbone. Upon reduction of [1](BF 4) 2 by either electrochemical or chemical means, one of its HBMIM Ph 2 ligandsu ndergoes deprotonation under the formation of dihydrogen.A ddition of am ild protons ource (acetic acid) to deprotonated complex [2](BF 4)r egenerates protonatedc omplex [1](BF 4) 2 .I np resenceo fa cetic acid in acetonitrile solvent[ 1](BF 4) 2 shows electrocatalytic proton reductionw ith a k obs of % 200 s À1 at an overpotential of 590 mV.M echanistic investigations supported by DFT (BP86) suggest that dihydrogen formation takes place in an intramolecular fashiont hrough the participation of am ethylene CÀHb ond of the HBMIM Ph 2 ligand andaCo II ÀHb ond through formal heterolytic splitting of the latter.T hese findings are of interestt ot he development of responsive ligands formolecular (base)metal(electro)catalysis.