Search results for "specificity"
showing 10 items of 2234 documents
Performance assessment to investigate the domain specificity of instructional skills among pre‐service and in‐service teachers of mathematics and eco…
2019
Background Key elements of instructional quality include the teacher's ability to immediately react in domain‐specific classroom situations. Such skills – defined as action‐related skills – can only be validly assessed using authentic representations of real‐life teaching practice. However, research has not yet explained how teachers apply domain‐specific knowledge for teaching and to what extent action‐related skills are transferable from one domain to another. Aims Our study aims to examine (1) the relationship between action‐related skills, content knowledge, and pedagogical content knowledge, and (2) the domain specificity of action‐related skills of (prospective) teachers in the two do…
Courtship in Drosophila
2000
0066-4197 (Print) Journal Article Review; Courtship is a complex behavior in Drosophila that recruits a wide range of genes for its realization, including those concerning sex determination, ion channels, and circadian rhythms. Results from different experimental approaches-behavioral and genetic comparisons between species, analysis of mutants and mosaics, and identification of specific sensory stimuli-sketch the outlines of a set of pleiotropic genes acting on a distributed system in the brain to produce the species-specific sequence of responses and actions.
The evolutionary history of the Arabidopsis arenosa complex: diverse tetraploids mask the Western Carpathian center of species and genetic diversity.
2012
The Arabidopsis arenosa complex is closely related to the model plant Arabidopsis thaliana. Species and subspecies in the complex are mainly biennial, predominantly outcrossing, herbaceous, and with a distribution range covering most parts of latitudes and the eastern reaches of Europe. In this study we present the first comprehensive evolutionary history of the A. arenosa species complex, covering its natural range, by using chromosome counts, nuclear AFLP data, and a maternally inherited marker from the chloroplast genome [trnL intron (trnL) and trnL/F intergenic spacer (trnL/F-IGS) of tRNA(Leu) and tRNA(Phe), respectively]. We unravel the broad-scale cytogeographic and phylogeographic pa…
Morphological Similarity and Ecological Overlap in Two Rotifer Species
2013
Co-occurrence of cryptic species raises theoretically relevant questions regarding their coexistence and ecological similarity. Given their great morphological similitude and close phylogenetic relationship (i.e., niche retention), these species will have similar ecological requirements and are expected to have strong competitive interactions. This raises the problem of finding the mechanisms that may explain the coexistence of cryptic species and challenges the conventional view of coexistence based on niche differentiation. The cryptic species complex of the rotifer Brachionus plicatilis is an excellent model to study these questions and to test hypotheses regarding ecological differentia…
Occurrence of a sibling species complex within neotropical lymnaeids, snail intermediate hosts of fascioliasis.
2002
The delimitation of cryptic species within the genus Lymnaea, which are the main vectors of fascioliasis, remains a topic of controversy. An analysis of genetic variability based on 12 enzyme loci revealed different fixed alleles at 9 loci between two sympatric samples of Lymnaea viatrix at the type locality in Lima, Peru. The absence of heterozygotes within this locality indicates the presence of isolated populations or cryptic species within L. viatrix. Significant genetic differences were also found between these two L. viatrix samples from Lima and other populations of L. viatrix in South America and in addition to species such as L. truncatula, L. cubensis and L. columella. Moreover, t…
The age and evolution of sociality in Stegodyphus spiders: a molecular phylogenetic perspective
2006
Social, cooperative breeding behaviour is rare in spiders and generally characterized by inbreeding, skewed sex ratios and high rates of colony turnover, processes that when combined may reduce genetic variation and lower individual fitness quickly. On these grounds, social spider species have been suggested to be unstable in evolutionary time, and hence sociality a rare phenomenon in spiders. Based on a partial molecular phylogeny of the genus Stegodyphus , we address the hypothesis that social spiders in this genus are evolutionary transient. We estimate the age of the three social species, test whether they represent an ancestral or derived state and assess diversification relative to s…
Efficient DNA Packaging of Bacteriophage PRD1 Requires the Unique Vertex Protein P6
2007
ABSTRACT The assembly of bacteriophage PRD1 proceeds via formation of empty procapsids containing an internal lipid membrane, into which the linear double-stranded DNA genome is subsequently packaged. The packaging ATPase P9 and other putative packaging proteins have been shown to be located at a unique vertex of the PRD1 capsid. Here, we describe the isolation and characterization of a suppressor-sensitive PRD1 mutant deficient in the unique vertex protein P6. Protein P6 was found to be an essential part of the PRD1 packaging machinery; its absence leads to greatly reduced packaging efficiency. Lack of P6 was not found to affect particle assembly, because in the P6-deficient mutant infecti…
Routine application using single quadrupole liquid chromatography-mass spectrometry to pesticides analysis in citrus fruits.
2005
Abstract A rapid and sensitive liquid chromatography–electrospray ionization–mass spectrometry method has been developed for the routine analysis of buprofezin, bupirimate, hexaflumuron, tebufenpyrad, fluvalinate and pyriproxyfen in citrus fruits. Extracts were obtained by matrix solid-phase dispersion (MSPD) using C 18 as dispersant and dichloromethane-methanol (80:20, v/v) as eluent. Matrix effects were tested for all matrices by addition of standard to sample blank extracts (samples containing no detectable residues). Mean recoveries obtained at fortification levels between 0.01 and 5 mg kg −1 were 57–97% with relative standard deviations (RSDs) from 5 to 19%. The limits of quantificatio…
Comparison of four mass analyzers for determining carbosulfan and its metabolites in citrus by liquid chromatography/mass spectrometry
2006
Four liquid chromatography/mass spectrometry (LC/MS) systems, equipped with single quadrupole, triple quadrupole (QqQ), quadrupole ion trap (QIT) and quadrupole time-of-flight (QqTOF) mass analyzers, were evaluated for the analysis of carbosulfan and its main transformation products. The comparison of quantitative aspects (sensitivity, precision and accuracy) was emphasized. Results showed that the triple quadrupole instrument reaches at least 20-fold higher sensitivity (LOD from 0.04 to 0.4 microg kg(-1)) compared to the single quadrupole (4-70 microg kg(-1)), the QIT (4-25 microg kg(-1)) and the QqTOF (4-23 microg kg(-1)) instruments. Recoveries were over 70% for all the analytes, except …
Direct infusion mass spectrometry as a fingerprint of protein-binding media used in works of art
2005
A direct infusion mass spectrometry method for the characterization of proteinaceous glues from binding media used in pictorial works of art prior to conservation or restoration treatment is proposed. Amino acids are released by acid hydrolysis and dissolved in a mixture of acidic water and ethanol. This mixture is directly infused into a mass spectrometer without any derivatization. The mass spectrometer is operated in positive ion electrospray mode (ESI-MS) to yield [M+H]+ ions for the amino acids. Relative amounts of each amino acid are calculated for each protein (beef and porcine gelatines, albumin, casein and egg). The analyzed proteins were satisfactorily distinguished. The method is…