Synonymy of Boophilus Curtice, 1891 with Rhipicephalus Koch, 1844 (Acari : Ixodidae)

Recent molecular and morphological studies of the genera Rhipicephalus Koch, 1844 and Boophilus Curtice, 1891 revealed that the five species of Boophilus make the genus Rhipicephalus paraphyletic. Thus, Rhipicephalus Koch, 1844 is not a monophyletic ( natural) lineage and some species of Rhipicephalus are more closely related to the species of Boophilus than to other species of Rhipicephalus. Here, we revise these genera: Boophilus is synonymised with Rhipicephalus, and Rhipicephalus ( sensu lato) ( including Boophilus) is redefined. By synonymising Boophilus with Rhipicephalus, we have changed the nomenclature so that it reflects our understanding of the phylogeny of these ticks. Boophilus is retained as a subgenus of Rhipicephalus, so the synonymy of Boophilus with Rhipicephalus does not result in the loss of the name Boophilus. In addition, Rhipicephalus is a well- known genus and the change proposed is simple - all five species of Boophilus become members of Rhipicephalus ( Boophilus).

Model studies on the role of citrate, malate and pectin esterification on the enzymatic degradation of Al- and Ca-pectate gels: possible implications for Al-tolerance

Aluminium (At) tolerance in plants may be conferred by reduced binding of Al in the cell wall through low root cation exchange capacity (CEC) or by organic acid exudation. Root CEC is related to the degree of esterification (DE) of pectin in the cell wall, and pectin hydrolysis plays a role in cell expansion. Therefore, it was hypothesised that Al-tolerant plants with a low root CEC maintain pectin hydrolysis in the presence of Al, allowing cell expansion to continue. Irrespective of the DE, binding of Al to pectin reduced the enzymatic hydrolysis of Al-pectin gels by polygalacturonase (E.C. 3.2.1.15). Pectin gels with calcium (Ca) were slightly hydrolysed by polygalacturonase. It was concluded, therefore, that Al tolerance conferred by low root CEC is not mediated by the ability to maintain pectin hydrolysis. Citrate and malate, but not acetate, effectively dissolved Al-pectate gel and led to hydrolysis of the dissolved pectin by polygalacturonase. The organic acids did not dissolve Ca-pectate, nor did they increase pectin hydrolysis by polygalacturonase. It was concluded that exudation of some organic acids can remove Al bound to pectin and this could alleviate toxicity, constituting a tolerance mechanism. (C) 2003 Editions scientitiques et medicales Elsevier SAS. All rights reserved.