Histopathology of <Emphasis Type=Italic>Rhipicephalus sanguineus</Emphasis> (Acari: Ixodidae) ticks fed on resistant hosts

Histological features of Rhipicephalus sanguineus ticks fed on dog, a non resistant host, and on guinea pig, a resistant host, were compared. Unfed ticks and ticks from each host species were collected during first and third infestation and processed for histology. Many ticks from guinea pigs, especially during third infestation, were unattached, dehydrated and small. Only the midgut of ticks fed on guinea pigs had host leukocytes. Vacuolization of midgut cells was observed in all ticks, with exception of those fed on dogs for more than 96 h. Ticks of guinea pigs, particularly from third infestation, had vacuolated tracheae and swelling of malpighian tubules. Solely ticks from third infestation of guinea pigs displayed vacuolization of oocytes. Ticks fed on guinea pigs also had an increased number of guanine spherules. Observed alterations in ticks from guinea pigs are discussed.     

Diversity and dynamics of free-living and particle-associated Betaproteobacteria and Actinobacteria in relation to phytoplankton and zooplankton communities

The diversity of attached and free-living Actinobacteria and Betaproteobacteria, based on 16S rRNA gene sequences, was investigated in a mesotrophic lake during two periods of contrasting phytoplankton dominance. Comparison analyses showed a phylogenetic difference between attached and free-living communities for the two bacterial groups. For Betaproteobacteria, the betaI clade was detected at all sampling dates in free-living and attached bacterial communities and was the dominant clade contributing to 57.8% of the total retrieved operational taxonomic units (OTUs). For Actinobacteria, the acIV cluster was found to be dominant, followed by acI contributing to 45% and 25% of the total retrieved OTUs, respectively. This study allows the determination of eight new putative clades among the Betaproteobacteria termed lbI-lbVIII and a new putative clade named acLBI belonging to the Actinobacteria. The seasonal dynamics of phytoplankton and zooplankton communities have been reflected as changes in distinct bacterial phylotypes for both attached and free-living communities. For attached communities, relationships were observed between Actinobacteria and Chrysophyceae, and between Betaproteobacteria and Dinophyceae and Chlorophyceae biomass. On the other hand, within free-living communities, few actinobacterial clades were found to be dependent on either nutrients or phytoplankton communities, whereas Betaproteobacteria were mainly associated with biological parameters (i.e. phytoplankton and copepod communities).     

Cortico-striatal representation of time in animals and humans

Interval timing in the seconds-to-minutes range is crucial to learning, memory, and decision-making. Recent findings argue for the involvement of cortico-striatal circuits that are optimized by the dopaminergic modulation of oscillatory activity and lateral connectivity at the level of cortico-striatal inputs. Striatal medium spiny neurons are proposed to detect the coincident activity of specific beat patterns of cortical oscillations, thereby permitting the discrimination of supra-second durations based upon the reoccurring patterns of subsecond neural firing. This proposal for the cortico-striatal representation of time is consistent with the observed psychophysical properties of interval timing (e.g. linear time scale and scalar variance) as well as much of the available pharmacological, lesion, patient, electrophysiological, and neuroimaging data from animals and humans (e.g. dopamine-related timing deficits in Huntington's and Parkinson's disease as well as related animal models). The conclusion is that although the striatum serves as a 'core timer', it is part of a distributed timing system involving the coordination of large-scale oscillatory networks.     

Psychometric Properties of the Autoquestionnaire Qualité De Vie Enfant Imagé (AUQEI) Applied to Children with Cerebral Palsy

BackgroundQuality of life (QL) assessments of children with incapacitating diseases, such as cerebral palsy (CP), have often been conducted with the help of the representatives of a child, making QL assessment more subjective. TheAutoquestionnaireQualité de Vie Enfant Imagé (AUQEI) is a QL assessment designed for children to self-report—it uses images to facilitate the reporting process.Objectiveevaluate the psychometric properties of AUQEI when responses are given by children with CP.FindingsChildren aged 4 to 12 years (45 with CP and 45 healthy children) gave responses to the questionnaire. The data quality, reliability and validity were assessed. The data loss rate ranged from 8.8% to 46.7%, and was highest for the “autonomy” factor. No floor or ceiling effect was detected. The success rate for reliability of the internal consistency of the items was less than 80% for the “autonomy” factor. Cronbach’s alpha coefficient was 0.71 for the instrument and less than 0.5 for the factors. All the factors had a success rate of greater than 80% for the discriminating validity of the items. The factors did not have correlations between each other, thus indicating adequate discriminating validity. Convergent validity was tested and a significant correlation was demonstrated only between the AUQEI “functioning” factor and the Child Health Questionnaire—50-Item (CHQ-PF50) physical summary score (r = 0.31, p = 0.042). The AUQEI scores did not have correlations with the gross motor function scores (p>0.05) as expected for divergent validity. Regarding construct validity, the total AUQEI score obtained by the CP group was lower (median: 47.3) than that of the healthy group (median: 51.0) (p<0.01).ConclusionThe AUQEI was shown to be a reliable and valid instrument for assessing children with CP when the total score was used. Convergent validity should continue to be tested in future studies.     

TLRs 2 and 4 are not involved in hypersusceptibility to acute Pseudomonas aeruginosa lung infections

TLRs are implicated in defense against microorganisms. Animal models have demonstrated that the susceptibility to a number of Gram-negative pathogens is linked to TLR4, and thus LPS of many Gram-negative bacteria have been implicated as virulence factors. To assess the role of this pathogen-associated molecular pattern as it is exposed on intact Pseudomonas aeruginosa, the susceptibility of mice lacking TLR4 or both TLR2 and TLR4 was examined in a model of acute Pseudomonas pneumonia. These mutant mice were not hypersusceptible to the Pseudomonas challenge and mounted an effective innate response that cleared the organism despite low levels of TNF-alpha and KC in the airways. Bacterial and neutrophil counts in the lung were similar in control and TLR-deficient mice at 6 and 24 h after infection. MyD88(-/-) mice were, however, hypersusceptible, with 100% of mice dying within 48 h with a lower dose of P. aeruginosa. Of note there were normal levels of IL-6 and G-CSF in the airways of TLR mutant mice that were absent from the MyD88(-/-) mice. Thus, the susceptibility of mice to P. aeruginosa acute lung infection does not go through TLR2 or TLR4, implying that Pseudomonas LPS is not the most important virulence factor in acute pneumonia caused by this organism. Furthermore, G-CSF treatment of infected MyD88(-/-) mice results in improved clearance and survival. Thus, the resistance to infection in TLR2/TLR4(-/-) mice may be linked to G-CSF and possibly IL-6 production.     

Stigma Diversity in Tropical Legumes with Considerations on Stigma Classification

The great stigma diversity in angiosperms implies a choice of criteria for stigma classification, which nowadays is characterized as dry (= little or no secretory surface and exudate retained by the cuticle and/or protein pellicle), wet (= conspicuous secretory surface, abundant in fluid exudate) and semidry (exudate retained by cuticle and/or protein pellicle). Despite being a very species-rich family, whose representatives exhibit a wide floral variation, no comparative studies of stigma diversity have been done for the whole Leguminosae. In order to assess the stigma morphological diversity in legumes and to evaluate the criteria used in the main classifications of the stigma, we compared the stigma morphology in 15 distinct legume lineages. In addition, we evaluated the stigma classification in other 152 legume species whose morphology was already described in the literature. Stigmas were removed from floral buds and flowers and processed for analyses under scanning electron and light microscopes. The stigma of the study legumes exhibits quite variable morphology, mainly concerning the diameter, the occurrence of an orifice or a furrow, the coating, the cellular composition, and the occurrence, chemical nature and release mechanism of the exudate. This diversity appears to be related mainly to the evolutionary history of the group and also to the selective pressures exerted by different types of pollen and pollinator. More conflicting criteria for stigma classification lie in defining the semidry type, found mostly in papilionoids. For better stigma classification we suggest that stigma morphology be evaluated at the time prior to anthesis, when the cuticle is not yet broken and the exudate is not exposed or drained. In addition, several techniques should be employed for a better classification.