Experimental infection of the tick Amblyomma cajennense, Cayenne tick, with Rickettsia rickettsii, the agent of Rocky Mountain spotted fever

In the laboratory, Amblyomma cajennense (Acari: Ixodidae) (Fabricius) larvae, nymphs and adults were exposed to Rickettsia rickettsii by feeding on needle-inoculated animals, and thereafter reared on uninfected guinea pigs or rabbits. Regardless of the tick stage that acquired the infection, subsequent tick stages were shown to be infected (confirming transstadial and transovarial transmissions) and were able to transmit R. rickettsii to uninfected animals, as demonstrated by serological and molecular analyses. However, the larval, nymphal and adult stages of A. cajennense were shown to be partially refractory to R. rickettsii infection, as in all cases, only part of the ticks became infected by this agent, after being exposed to rickettsemic animals. In addition, less than 50% of the infected engorged females transmitted rickettsiae transovarially, and when they did so, only part of the offspring became infected, indicating that vertical transmission alone is not enough to maintain R. rickettsii in A. cajennense for multiple generations. Finally, the R. rickettsii-infected tick groups had lower reproductive performance than the uninfected control group. Our results indicate that A. cajennense have a low efficiency to maintain R. rickettsii for successive generations, as R. rickettsii-infection rates should decline drastically throughout the successive tick generations.

EQUIVALENCE OF REAL MILNOR FIBRATIONS FOR QUASI-HOMOGENEOUS SINGULARITIES

We show that for real quasi-homogeneous singularities f : (R-m, 0) -> (R-2, 0) with isolated singular point at the origin, the projection map of the Milnor fibration S-epsilon(m-1) \ K-epsilon -> S-1 is given by f/parallel to f parallel to. Moreover, for these singularities the two versions of the Milnor fibration, on the sphere and on a Milnor tube, are equivalent. In order to prove this, we show that the flow of the Euler vector field plays and important role. In addition, we present, in an easy way, a characterization of the critical points of the projection (f/parallel to f parallel to) : S-epsilon(m-1) \ K-epsilon -> S-1.

Natural blood feeding and temperature shift modulate the global transcriptional profile of Rickettsia rickettsii infecting its tick vector

Rickettsia rickettsii is an obligate intracellular tick-borne bacterium that causes Rocky Mountain Spotted Fever (RMSF), the most lethal spotted fever rickettsiosis. When an infected starving tick begins blood feeding from a vertebrate host, R. rickettsii is exposed to a temperature elevation and to components in the blood meal. These two environmental stimuli have been previously associated with the reactivation of rickettsial virulence in ticks, but the factors responsible for this phenotype conversion have not been completely elucidated. Using customized oligonucleotide microarrays and high-throughput microfluidic qRT-PCR, we analyzed the effects of a 10 degrees C temperature elevation and of a blood meal on the transcriptional profile of R. rickettsii infecting the tick Amblyomma aureolatum. This is the first study of the transcriptome of a bacterium in the genus Rickettsia infecting a natural tick vector. Although both stimuli significantly increased bacterial load, blood feeding had a greater effect, modulating five-fold more genes than the temperature upshift. Certain components of the Type IV Secretion System (T4SS) were up-regulated by blood feeding. This suggests that this important bacterial transport system may be utilized to secrete effectors during the tick vector's blood meal. Blood feeding also up-regulated the expression of antioxidant enzymes, which might correspond to an attempt by R. rickettsii to protect itself against the deleterious effects of free radicals produced by fed ticks. The modulated genes identified in this study, including those encoding hypothetical proteins, require further functional analysis and may have potential as future targets for vaccine development.

Crenicichla chicha, a new species of pike cichlid (Teleostei: Cichlidae) from the rio Papagaio, upper rio Tapajos basin, Mato Grosso, Brazil

Crenicichla chicha, new species, occurs in clear, fast-running waters with rocky substrates in the rio Papagaio and tributaries. It is distinguished from all other Crenicichla species by the combination of two character states: infraorbitals 3 and 4 co-ossified (vs. separated) and 66-75 scales in the row immediately above to that containing the lower lateral line (E1 row scales). Crenicichla chicha shares a smooth preopercular margin, co-ossification of infraorbitals 3 and 4, and some color features with C. hemera from the adjacent rio Aripuana drainage, rio Madeira basin. It differs from Crenicichla hemera in more E1 scales (6675 vs. 58-65) and presence of a conspicuous black narrow stripe running from infraorbital 3 obliquely caudoventrad toward the preopercular margin vs. a rounded and faint suborbital marking present on infraorbitals 3-4. Examination of the type series and additional material from the rio Aripuana confirms that Crenicichla guentheri Ploeg, 1991 is a junior subjective synonym of C. hemera Kullander, 1990.

Crenicichla chicha, a new species of pike cichlid (Teleostei: Cichlidae) from the rio Papagaio, upper rio Tapajós basin, Mato Grosso, Brazil

Crenicichla chicha, new species, occurs in clear, fast-running waters with rocky substrates in the rio Papagaio and tributaries. It is distinguished from all other Crenicichla species by the combination of two character states: infraorbitals 3 and 4 co-ossified (vs. separated) and 66-75 scales in the row immediately above to that containing the lower lateral line (E1 row scales). Crenicichla chicha shares a smooth preopercular margin, co-ossification of infraorbitals 3 and 4, and some color features with C. hemera from the adjacent rio Aripuanã drainage, rio Madeira basin. It differs from Crenicichla hemera in more E1 scales (66-75 vs. 58-65) and presence of a conspicuous black narrow stripe running from infraorbital 3 obliquely caudoventrad toward the preopercular margin vs. a rounded and faint suborbital marking present on infraorbitals 3-4. Examination of the type series and additional material from the rio Aripuanã confirms that Crenicichla guentheri Ploeg, 1991 is a junior subjective synonym of C. hemera Kullander, 1990.

Ornithodoros guaporensis (Acari, Ixodida: Argasidae), a new tick species from the Guaporé River Basin in the Bolivian Amazon

The soft tick Ornithodoros guaporensis n. sp. (Acari: Ixodida: Argasidae) is described from larvae and adults. Morphological analysis and 16S rDNA sequences are provided. Adults were collected from a rocky fissure inhabited by bats located in the Amazonian forest in north-eastern Bolivia (Beni Department) close to the Guaporé River. Larvae were obtained from eggs laid by females collected in the field, and which were fed on rabbits in the laboratory. Larvae of O. guaporensis are morphologically closely related to Ornithodoros rioplatensis, Ornithodoros puertoricensis and Orni-thodoros talaje. Larvae of O. guaporensis and O. rioplatensis can be separated from O. puertoricensis and O. talaje by the number of pairs of dorsal setae (20 in O. guaporensis and O. rioplatensis, 18 in O. puertoricensis and 17 in O. talaje). Larvae of O. guaporensis and O. rioplatensis can be differentiated by the medial dental formula (2/2 in O. guaporensis and 3/3 in O. rioplatensis) and the apex of the hypostome, which is more pointed in O. rioplatensis than in O. guaporensis. The Principal Component Analysis performed with morphometric characters of larvae showed a clear separation among O. guaporensis, O. rioplatensis, O. puertoricensis and O. talaje. Significant morphological differences among adults of these four species were not found. The analysis of the 16S rDNA sequences allowed for the differentiation between O. guaporensis and the remaining Neotropical species of the family Argasidae.