Search results for "Specificity."

Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography.

2005

In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous…

Sympatric and allopatric experimental infections of the planorbid snail Gyraulus chinensis with miracidia of Euparyphium albuferensis (Trematoda: Ech…

2010

AbstractAn experimental infection with echinostomatid miracidia in sympatric or ‘local’ vs. allopatric or ‘away’ snail combinations, as a model to examine parasite compatibility, was carried out. We employedEuparyphium albuferensismiracidia to infectGyraulus chinensissnails, from three different natural parks: Albufera (Valencia, Spain); the Ebro Delta (Tarragona, Spain) and Coto de Doñana (Huelva, Spain). Insignificant differences between the three snail strains were noted for the infection rate and the rhythm of daily cercarial production. However, a significantly higher total cercarial production per snail, patent period and life span were observed in local snails. The different infectio…

Biological invasion and parasitism: invaders do not suffer from physiological alterations of the acanthocephalan Pomphorhynchus laevis.

2009

SUMMARYBiological invasions expose parasites to new invasive hosts in addition to their local hosts. However, local parasites are often less successful in infecting and exploiting their new hosts. This may have major consequences for the competitive ability of hosts, and finally on the fate of the parasite-host community. In Burgundy (Eastern France), the acanthocephalan parasite,Pomphorhynchus laevis, infects 2 amphipod species living in sympatry: the nativeGammarus pulexand the invasiveGammarus roeseli. WhileP. laevisaffects the behaviour and the immunity ofG. pulex,G. roeseliseems unaffected by the infection. In this study, we examined in detail the ability of the parasite to affect the …

Interspecific aggression and character displacement in the damselfly Calopteryx splendens

2004

Problems in species recognition are thought to affect the evolution of secondary sexual characters mainly through avoidance of maladaptive hybridization. Another, but much less studied avenue for the evolution of sexual characters due to species recognition problems is through interspecific aggression. In the damselfly, Calopteryx splendens, males have pigmented wing spots as a sexual character. Large-spotted males resemble males of another species, Calopteryx virgo, causing potential problems in species recognition. In this study, we investigate whether there is character displacement in wing spot size and whether interspecific aggression could cause this pattern. We found first that wing …

Molecules and morphology reveal cryptic variation among digeneans infecting sympatric mullets in the Mediterranean.

2009

SUMMARYWe applied a combined molecular and morphological approach to resolve the taxonomic status of Saccocoelium spp. parasitizing sympatric mullets (Mugilidae) in the Mediterranean. Eight morphotypes of Saccocoelium were distinguished by means of multivariate statistical analyses: 2 of Saccocoelium obesum ex Liza spp.; 4 of S. tensum ex Liza spp.; and 2 (S. cephali and Saccocoelium sp.) ex Mugil cephalus. Sequences of the 28S and ITS2 rRNA gene regions were obtained for a total of 21 isolates of these morphotypes. Combining sequence data analysis with a detailed morphological and multivariate morphometric study of the specimens allowed the demonstration of cryptic diversity thus rejecting…

What do we need to know about speciation?

2011

Speciation has been a major focus of evolutionary biology research in recent years, with many important advances. However, some of the traditional organising principles of the subject area no longer provide a satisfactory framework, such as the classification of speciation mechanisms by geographical context into allopatric, parapatric and sympatry classes. Therefore, we have asked where speciation research should be directed in the coming years. Here, we present a distillation of questions about the mechanisms of speciation, the genetic basis of speciation and the relationship between speciation and diversity. Our list of topics is not exhaustive; rather we aim to promote discussion on rese…

Superresolved digital in-line holographic microscopy for high-resolution lensless biological imaging.

2010

Digital in-line holographic microscopy (DIHM) is a modern approach capable of achieving micron-range lateral and depth resolutions in three-dimensional imaging. DIHM in combination with numerical imaging reconstruction uses an extremely simplified setup while retaining the advantages provided by holography with enhanced capabilities derived from algorithmic digital processing. We introduce superresolved DIHM incoming from time and angular multiplexing of the sample spatial frequency information and yielding in the generation of a synthetic aperture (SA). The SA expands the cutoff frequency of the imaging system, allowing submicron resolutions in both transversal and axial directions. The pr…

A fully synthetic vaccine consisting of a tumor-associated glycopeptide antigen and a T-cell epitope for the induction of a highly specific humoral i…

2005

An identifiable model to assess frequency-domain Granger causality in the presence of significant instantaneous interactions

2010

We present a new approach for the investigation of Granger causality in the frequency domain by means of the partial directed coherence (PDC). The approach is based on the utilization of an extended multivariate autoregressive (MVAR) model, including instantaneous effects in addition to the lagged effects traditionally studied, to fit the observed multiple time series prior to PDC computation. Model identification is performed combining standard MVAR coefficient estimation with a recent technique for instantaneous causal modeling based on independent component analysis. The approach is first validated on simulated MVAR processes showing that, in the presence of instantaneous effects, only t…

Reviewing lymnaeid vectors of fascioliasis by ribosomal DNA sequence analyses.

2005

AbstractSnails of the family Lymnaeidae are of great parasitological importance due to the numerous helminth species they transmit, mainly trematodiases (such as fascioliasis) of considerable medical and veterinary impact. The present knowledge of the genetics and host–parasite relationships of this gastropod group is far from adequate. Fascioliasis is caused by two species, Fasciola hepatica and F. gigantica, which, as in the case of other trematodes, show a marked snail host specificity. Many lymnaeid species involved in fascioliasis transmission still show a confused systematic-taxonomic status. The need for tools to distinguish and characterize species and populations of lymnaeids is ev…