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Evaluation of a Commercial Enzyme Linked Immunosorbent Assay (ELISA) for the Determination of the Neurotoxin BMAA in Surface Waters
Get PDFSelfing and othering through categories of race, place, and language among minority youths in Rotterdam, The Netherlands
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From high heels to weed attics: a syntactic investigation of chick lit and literature
No full textStylometric analysis of prose is typically limited
to classification tasks such as authorship
attribution. Since the models used are typically
black boxes, they give little insight into
the stylistic diff erences they detect. In this
paper, we characterize two prose genres syntactically:
chick lit (humorous novels on the
challenges of being a modern-day urban female)
and high literature. First, we develop
a top-down computational method based on
existing literary-linguistic theory. Using an
o -the-shelf parser we obtain syntactic structures
for a Dutch corpus of novels and measure
the distribution of sentence types in chick-lit
and literary novels. The results show that literature
contains more complex (subordinating)
sentences than chick lit. Secondly, a bottom-up
analysis is made of specific morphological and
syntactic features in both genres, based on the
parser’s output. This shows that the two genres
can be distinguished along certain features.
Our results indicate that detailed insight into
stylistic di fferences can be obtained by combining
computational linguistic analysis with
literary theory.
Evolutionary response of the egg hatching date of a herbivorous insect under climate change
No full textUnder changing climatic conditions, species need to adapt to their new environment. Genetic adaptation is crucial to prevent population extinction1 but examples where climate change leads to genetic changes in wild populations have been few2, 3. The synchronization between the timing of egg hatching of a herbivorous insect, the winter moth (Operophtera brumata), and the seasonal bud burst of its food plant, oak (Quercus robur), has been disrupted by climate change4 and a quantitative genetic model predicts that selection will delay the egg hatching date5. Here we show, using both long-term observational data and experiments, that the egg hatching date has changed genetically, resulting in closer synchrony with oak bud burst. The observed rate of change matches the predicted rate of change of one day per year. Hence, altered selection pressures, caused by environmental change, result in a rapid adaptive response in insect phenology. These genetic changes in a key life-history trait in this herbivorous insect therefore seem to be fast enough to match the climate-change-induced advancement of their host phenology.
Explaining bacterial dispersion on leaf surfaces with an individual-based model (PHYLLOSIM)
No full textWe developed the individual-based model PHYLLOSIM to explain observed variation in the size of bacterial clusters on plant leaf surfaces (the phyllosphere). Specifically, we tested how different ‘waterscapes’ impacted the diffusion of nutrients from the leaf interior to the surface and the growth of individual bacteria on these nutrients. In the ‘null’ model or more complex ‘patchy’ models, the surface was covered with a continuous water film or with water drops of equal or different volumes, respectively. While these models predicted the growth of individual bacterial immigrants into clusters of variable sizes, they were unable to reproduce experimentally derived, previously published patterns of dispersion which were characterized by a much larger variation in cluster sizes and a disproportionate occurrence of clusters consisting of only one or two bacteria. The fit of model predictions to experimental data was about equally poor (<5%) regardless of whether the water films were continuous or patchy. Only by allowing individual bacteria to detach from developing clusters and re-attach elsewhere to start a new cluster, did PHYLLOSIM come much closer to reproducing experimental observations. The goodness of fit including detachment increased to about 70–80% for all waterscapes. Predictions of this ‘detachment’ model were further supported by the visualization and quantification of bacterial detachment and attachment events at an agarose-water interface. Thus, both model and experiment suggest that detachment of bacterial cells from clusters is an important mechanism underlying bacterial exploration of the phyllosphere.
The importance of aboveground-belowground interactions on the evolution and maintenance of variation in plant defence traits
No full textOver the past two decades a growing body of empirical research has shown that many ecological processes are mediated by a complex array of indirect interactions occurring between rhizosphere-inhabiting organisms and those found on aboveground plant parts. Aboveground - belowground studies have thus far focused on elucidating processes and underlying mechanisms that mediate the behavior and performance of invertebrates in opposite compartments. Less is known about genetic variation in plant traits as this applies to an above- belowground framework. For instance, although the field of genetic variation in aboveground plant traits on community-level interactions is well developed, most studies have ignored genetic variation in plant traits – such as defence - that may have evolved in response to pressures from the combined effects of above- and below ground interactions from antagonists and mutualists. Here, we discuss gaps in our understanding of genetic variation in plant- and consumer-related traits as they relate to aboveground and belowground multitrophic interactions. When metabolic resources are limiting, then multiple attack by antagonists in both domains may lead to trade-offs in where these resources are optimally invested. In nature, these trade-offs may critically depend upon their effects on plant fitness. Natural enemies of herbivores may also influence selection for different traits via top-down control. At larger scales these interactions may generate evolutionary ‘hotspots’ where the expression of various plant traits is the result of strong reciprocal selection via direct and indirect interactions. The role of abiotic factors in driving genetic variation in plant traits is also discussed.
