Comparison of a modified assay method for the endopeptidase marker Ep-D1b with the Sequence Tag Site marker XustSSR2001–7DL for strawbreaker foot rot resistance in wheat

The endopeptidase marker Ep‐D1b and Sequence Tag Site (STS) marker XustSSR2001–7DL were reported to be closely associated with the most effective resistance gene (Pch1) in wheat (Triticum aestivum L.) for strawbreaker foot rot [Pseudocercosporella herpotrichoides (Fron) Deighton]. Our objectives were to: (i) develop an efficient assay method for Ep‐D1b in wheat; (ii) correlate endopeptidase zymograms to strawbreaker foot rot reactions of various wheat genotypes; and (iii) compare the utility of Ep‐D1b and XustSSR2001–7DL for predicting disease response. An improved method of assaying for the Ep‐D1b marker using roots from a single seedling was developed, which is a 2.5‐fold improvement over the previous method. Thirty‐eight wheat genotypes with known reactions to strawbreaker foot rot were analysed for Ep‐D1b and the STS marker. Six distinct endopeptidase zymograms were identified among these 38 genotypes tested, and three of these patterns were novel. The endopeptidase marker was 100% accurate for predicting strawbreaker foot rot disease response, whereas the STS marker predicted the correct phenotype with approximately 90% accuracy. The endopeptidase marker Ep‐D1b was more effective and was more economical for use in marker‐assisted selection strategies for Pch1 in our laboratory compared with the STS marker.     

The case for liming some Nova Scotia salmon rivers

Long range transport of H₂SO₄ has caused many Nova Scotian rivers to decline in pH to the point where their Atlantic salmon (Salmo salar) stocks have been destroyed or much diminished. Chemical records show a declining pH trend in N.S. rivers since the early 1950's. The annual variation in hydrogen ion activity is positively correlated with sulphate and Al and negatively correlated with organic anions. It is technically feasible to restore the acidified salmon habitat by the addition of limestone, and the total cost of mounting a liming program to restore the lost habitat has been calculated. The pre-acidification Atlantic salmon production capacity was estimated from physical habitat surveys and tag return data. The estimated costs of the liming program are much greater than the anticipated economic benefits of the salmon restoration. Present plans are for a small liming program to establish a series of refuges for the preservation of nuclei of native salmon stocks.     

Changes in Collembola richness and diversity along a gradient of land-use intensity: A pan European study

Changes in Collembola richness and diversity along a land-use intensity gradient were studied in eight European countries (Portugal, Spain, France, Switzerland, Hungary, UK, Ireland and Finland). In each country a set of six 1 km² land-use units (LUUs) were selected forming a gradient ranging from natural forest to agricultural dominated landscapes, passing through mixed-use ones. In addition to data on Collembola, detailed information regarding landscape diversity and structure was collected for each LUU. A total of 47,774 individuals were identified from 281 species. Collembola reacted not only to changes in the diversity of the landscape, but also to the composition of that diversity and the area occupied by each land-use type at each LUU. Although species richness patterns were not concordant among the different countries, the total number of species per LUU (landscape richness) was generally higher in natural forests and mixed-used landscapes, and lower in agricultural dominated landscapes. Moreover, high richness and diversity of Collembola at each LUU were associated with a diverse landscape structure, both in terms of number of patches and patch richness. Despite this comparable species richness between mixed-use landscapes and those dominated by natural forests, average species richness on forested areas (local richness) decreased along the gradient, showing that forest patches on mixed-use landscapes support a lower richness than in landscapes dominated by forest. This aspect is important when addressing the role of native forests in structuring biodiversity in disturbed and fragmented landscapes. Although a diverse landscape can support a high biodiversity, the results suggest that intensive fragmentation should be avoided with the risk of collapsing local species richness with the consequent result for regional biodiversity.     

Congenital hepatoblastoma in a neonatal alpaca cria.

A neonatal alpaca cria found to have minimal clinical abnormalities was diagnosed postmortem with an epithelial-type hepatoblastoma with combined embryonal and fetal patterns, based on previously reported morphological features. Camelid neoplasia and domestic animal hepatoblastomas are very rare, with only a single case of congenital hepatoblastoma in a domestic animal previously reported.     

Spatial orientation in weightlessness and readaptation to earth's gravity

Unusual vestibular responses to head movements in weightlessness may produce spatial orientation illusions and symptoms of space motion sickness. An integrated set of experiments was performed during Spacelab 1, as well as before and after the flight, to evaluate responses mediated by the otolith organs and semicircular canals. A variety of measurements were used, including eye movements, postural control, perception of orientation, and susceptibility to space sickness.     

Water-soluble quantum dots for multiphoton fluorescence imaging in vivo

The use of semiconductor nanocrystals (quantum dots) as fluorescent labels for multiphoton microscopy enables multicolor imaging in demanding biological environments such as living tissue. We characterized water-soluble cadmium selenide-zinc sulfide quantum dots for multiphoton imaging in live animals. These fluorescent probes have two-photon action cross sections as high as 47,000 Goeppert-Mayer units, by far the largest of any label used in multiphoton microscopy. We visualized quantum dots dynamically through the skin of living mice, in capillaries hundreds of micrometers deep. We found no evidence of blinking (fluorescence intermittency) in solution on nanosecond to millisecond time scales.     

Transmission of small ruminant lentiviruses

Small ruminant lentiviruses (SRLV) are classical slow retroviruses causing chronic inflammatory disease in a variety of target organs. The routes of transmission have been investigated and a large body of evidence has accumulated over many years. The main routes are through ingestion of infected colostrum and/or milk, or through inhalation of respiratory secretions. However, many studies also provide evidence that intrauterine infection may occur, though the extent and significance of this route is controversial. Embryos treated to IETS standards appear to pose very little risk of infection. SRLV have been detected in semen suggesting a potential source of transmission. However, such transmission has not been demonstrated to date. The application of control measures based on this information allows more efficient strategies to be developed which will reduce the rate of transmission.