Studying Developmental Variation with Geometric Morphometric Image Analysis (GMIA)

The ways in which embryo development can vary across individuals of a population determine how genetic variation translates into adult phenotypic variation. The study of developmental variation has been hampered by the lack of quantitative methods for the joint analysis of embryo shape and the spatial distribution of cellular activity within the developing embryo geometry. By drawing from the strength of geometric morphometrics and pixel/voxel-based image analysis, we present a new approach for the biometric analysis of two-dimensional and three-dimensional embryonic images. Well-differentiated structures are described in terms of their shape, whereas structures with diffuse boundaries, such as emerging cell condensations or molecular gradients, are described as spatial patterns of intensities. We applied this approach to microscopic images of the tail fins of larval and juvenile rainbow trout. Inter-individual variation of shape and cell density was found highly spatially structured across the tail fin and temporally dynamic throughout the investigated period.     

Interspecific interactions between feral pigs and native birds reveal both positive and negative effects

In tropical Australian rainforests, predators and scavengers aggregate beneath emergent trees that house large colonies of metallic starlings (Aplonis metallica), feeding in the nutrient‐rich open areas below. Analysis of camera‐trap records shows that the presence of feral pigs (Sus scrofa) is associated with an absence of birds (cockatoos and brush turkeys), presumably reflecting behavioural avoidance (pigs pose a direct danger to birds). However, bird numbers increase as soon as pigs depart, then fall if pigs are absent for long periods. Feral pigs thus displace native birds from these resource hotspots; but by turning over the soil and enhancing the birds' access to food, the pigs also have a positive impact on food availability for the avifauna. Thus, although invasive species have caused irreparable environmental damages worldwide, they may also provide positive benefits for certain species. The net benefit of such interspecific interactions will depend on the outcome of both positive and negative effects.     

How Much Is Enough? Minimal Responses of Water Quality and Stream Biota to Partial Retrofit Stormwater Management in a Suburban Neighborhood

Decentralized stormwater management approaches (e.g., biofiltration swales, pervious pavement, green roofs, rain gardens) that capture, detain, infiltrate, and filter runoff are now commonly used to minimize the impacts of stormwater runoff from impervious surfaces on aquatic ecosystems. However, there is little research on the effectiveness of retrofit, parcel-scale stormwater management practices for improving downstream aquatic ecosystem health. A reverse auction was used to encourage homeowners to mitigate stormwater on their property within the suburban, 1.8 km² Shepherd Creek catchment in Cincinnati, Ohio (USA). In 2007–2008, 165 rain barrels and 81 rain gardens were installed on 30% of the properties in four experimental (treatment) subcatchments, and two additional subcatchments were maintained as controls. At the base of the subcatchments, we sampled monthly baseflow water quality, and seasonal (5×/year) physical habitat, periphyton assemblages, and macroinvertebrate assemblages in the streams for the three years before and after treatment implementation. Given the minor reductions in directly connected impervious area from the rain barrel installations (11.6% to 10.4% in the most impaired subcatchment) and high total impervious levels (13.1% to 19.9% in experimental subcatchments), we expected minor or no responses of water quality and biota to stormwater management. There were trends of increased conductivity, iron, and sulfate for control sites, but no such contemporaneous trends for experimental sites. The minor effects of treatment on streamflow volume and water quality did not translate into changes in biotic health, and the few periphyton and macroinvertebrate responses could be explained by factors not associated with the treatment (e.g., vegetation clearing, drought conditions). Improvement of overall stream health is unlikely without additional treatment of major impervious surfaces (including roads, apartment buildings, and parking lots). Further research is needed to define the minimum effect threshold and restoration trajectories for retrofitting catchments to improve the health of stream ecosystems.     

Degradation of nuclear proteins: studies on transplanted B82 cell karyoplast proteins

Karyoplasts were prepared from B82 cells (thymidine kinase deficient mouse L cells) by cytochalasin B mediated enucleation. Morphological measurements show that the nucleus constitutes 89% of a karyoplast by volume. Homokaryons were obtained by Sendai virus mediated karyoplast-B82 cell fusion. Transplanted nuclei were not destroyed catastrophically but were maintained intracellularly for at least 140 h. Transplanted nuclear proteins were degraded with an average half-life of 84 +/- 7 h by processes partially sensitive to inhibition by NH4Cl (50%) and leupeptin (30%). The data therefore suggest that some nuclear proteins are translocated to the cytoplasm for lysosomal degradation.     

Untersuchungen über die Chlorophyllase

Ohne ZusammenfassungMit 4 Textabbildungen.