Induction, expression and characterisation of laccase genes from the marine-derived fungal strains Nigrospora sp. CBMAI 1328 and Arthopyrenia sp. CBMAI 1330

The capability of the fungi Nigrospora sp. CBMAI 1328 and Arthopyrenia sp. CBMAI 1330 isolated from marine sponge to synthesise laccases (Lcc) in the presence of the inducer copper (110 M) was assessed. In a liquid culture medium supplemented with 5 M of copper sulphate after 5 days of incubation, Nigrospora sp. presented the highest Lcc activity (25.2 UL1). The effect of copper on Lcc gene expression was evaluated by reverse transcriptase polymerase chain reaction. Nigrospora sp. showed the highest gene expression of Lcc under the same conditions of Lcc synthesis. The highest Lcc expression by the Arthopyrenia sp. was detected at 96 h of incubation in absence of copper. Molecular approaches allowed the detection of Lcc isozymes and suggest the presence of at least two undescribed putative genes. Additionally, Lcc sequences from the both fungal strains clustered with other Lcc sequences from other fungi that inhabit marine environments.M. Passarini was supported by Ph.D. grant from FAPESP (2008/06720-7), Sao Paulo, Brazil. The authors thank FAPESP for financial support (BIOTA-FAPESP grant 2010/50190-2 and FAPESP grant 2013/19486-0) and Roberto G.S. Berlinck and CEBIMAR for the support related to samples collecting. L.D. Sette thanks CNPq for Productivity Fellowships 304103/2013-6

Acaricide resistance mechanisms in Rhipicephalus (Boophilus) microplus Mecanismos de resistência aos acaricidas em Rhipicephalus (Boophilus) microplus

Acaricide resistance has become widespread in countries where cattle ticks, Rhipicephalus (Boophilus) microplus, are a problem. Resistance arises through genetic changes in a cattle tick population that causes modifications to the target site, increased metabolism or sequestration of the acaricide, or reduced ability of the acaricide to penetrate through the outer protective layers of the tick&#8217;s body. We review the molecular and biochemical mechanisms of acaricide resistance that have been shown to be functional in R. (B.) microplus. From a mechanistic point of view, resistance to pyrethroids has been characterized to a greater degree than any other acaricide class. Although a great deal of research has gone into discovery of the mechanisms that cause organophosphate resistance, very little is defined at the molecular level and organophosphate resistance seems to be maintained through a complex and multifactorial process. The resistance mechanisms for other acaricides are less well understood. The target sites of fipronil and the macrocyclic lactones are known and resistance mechanism studies are in the early stages. The target site of amitraz has not been definitively identified and this is hampering mechanistic studies on this acaricide.<br>A resistência aos acaricidas tornou-se amplamente difundida nos países onde os carrapatos bovinos, Rhipicephalus .Boophilus. microplus, são um problema. A resistência surge por meio de alterações genéticas em umapopulação de carrapatos que causam modificações no local de ação, aumento do metabolismo ou sequestro do acaricida, ou ainda redução na capacidade do acaricida em penetrar através das camadas protetoras do corpo do carrapato. Neste artigo, foram revisados os mecanismos moleculares e bioquímicos da resistência aos acaricidas que ocorrem em R. (B.) microplus. A partir de um ponto de vista dos mecanismos envolvidos, a resistência aos piretróides tem sido caracterizada em maior grau do que em qualquer outra classe de acaricida. Embora uma grande quantidade de pesquisas têm sido direcionada para a descoberta de mecanismos que causam resistência aos organofosforados, muito pouco é conhecido ao nível molecular, e essa resistência parece ser mantida por intermédio de um processo multifatorial e complexo. Os mecanismos de resistência para os demais acaricidas são bem menos compreendidos. Os alvos de ação do fipronil e das lactonas macrocíclicas são conhecidos, e os estudos dos mecanismos de ação envolvidos estão ainda em estágios iniciais. O alvo de ação do amitraz ainda não foi definitivamente identificado, e isso é limitante aos estudos dos mecanismos envolvidos na resistência a esse acaricida