Conservation assessment of British limestone pavements based on floristic criteria

The total British area of limestone pavement is very small, yet this scarce resource is being destroyed to supply decorative stone. Its scientific interest is both geological and botanical. Exploiting an exhaustive survey, a weighted index was developed for assessing the conservation value of limestone pavements based on their deep grike floras. Using weighted indices, 27 sites in Cumbria, Gwynedd, Lancashire, North Yorkshire and Skye were identified as important for the conservation of limestone pavement floras.     

Inhibition of telomerase in canine cancer cells following telomestatin treatment

Telomere shortening in normal somatic cells has been proposed as a major barrier to unlimited cellular proliferation. Telomerase is an enzyme capable of maintaining telomere length, and thus bypassing this barrier. In human beings, telomerase activity is restricted to cancer cells and cells of stem or germ cell lineages. Dogs represent a potentially useful clinical model for the development of telomerase‐based therapies because telomerase activity is also restricted to cancer cells and stem cells in this species. We examined the ability of telomestatin to inhibit telomerase activity in telomerase‐positive D17 and CMT7 canine cancer cell lines. At a concentration of 2 μM, telomestatin treatment resulted in a decrease in telomerase activity, telomere shortening, growth inhibition and apoptosis in telomerase‐positive cancer cells. These effects were not seen in telomerase‐negative skin fibroblasts or negative controls. These results confirm that telomestatin specifically inhibits telomerase activity in canine cancer cells and strengthens the usefulness of dogs as a model for testing telomerase‐based therapies.     

Microbial biomass and respiratory activity in soil aggregates of different sizes from three beechwood sites on a basalt hill

We studied the effects of aggregates of different sizes on the soil microbial biomass. The distribution of aggregate size classes (<2, 2–4, 4–10, >10 mm) in the upper mineral soil horizon (A_h layer) was very different in three sites (upper, intermediate, lower) in a beechwood (Fagus sylvatica) on a basalt hill (Germany). Aggregates of different sizes (<2, 2–4, 4–10 mm) contained different amounts of C and N but the C:N ratios were similar. C and N contents were generally higher in smaller aggregates. The maximum initial respiratory response by microorganisms in intact aggregates and in aggregates passed through a 1-mm sieve declined with the aggregate size, but the difference was more pronounced in intact aggregates. Disruption of aggregates generally increased this response, particularly in 4- to 10-mm aggregates in the lower site. Basal respiration differed strongly among sites, but was similar in each of the aggregate size classes. Aggregate size did not significantly affect the specific respiration (g O₂ g^–1 microbial C h^–1) nor the microbial: organic C ratio, but these parameters differed among sites. Microbial growth was increased strongly by passing the soil through a 1-mm sieve in each of the aggregate materials. The growth of microorganisms in disrupted aggregates was similar, and the effect of aggregate disruption depended on the growth of microorganisms in intact aggregates.     

Primary orthostatic tremor in Great Danes

Two Great Danes were presented for an investigation of 6-month histories of incessant tremor of all 4 limbs and trunk occurring only when the dogs were standing at rest. Dog 1 was a 2-year-old intact female harlequin Great Dane living in the UK, and dog 2 was a 2-year-old castrated male fawn Great Dane living in the United States. The owners described both dogs as having constant quivering of the limbs while standing, suggestive of an involuntary dance, since the age of 18 months. The intensity of the tremors was reported in both dogs to have steadily increased since onset. In dog 1, tremors were noticed to be more pronounced in the fore limbs when she was eating and more pronounced in the hind limbs when she was trying to sit. The owner of dog 1 also reported that the dog could no longer assume a position of recumbency without manual assistance because of the severity of the tremors. Intermittently, tremors were reported to involve the facial musculature of dog 2. Vaccinations were current, and the owners of both dogs did not report any previous medical history, exposure to natural or manufactured toxins, or concurrent treatment. No familial relationship was identified between these 2 dogs.     

Genetic structure and diversity among sheep breeds in the United States: identification of the major gene pools

Understanding existing levels of genetic diversity of sheep breeds facilitates in situ and ex situ conservation activities. A comprehensive evaluation of US sheep breeds has not been previously performed; therefore, we evaluated the genetic diversity among and within 28 US sheep breeds. Both major and minor breeds were included in the analysis and consisted of 666 animals from 222 producers located in 38 states. The level of within-breed genetic diversity was variable and not dependent upon status of a breed as a major or minor breed. Bayesian cluster analysis indicated the breeds were grouped more by physiological differences (meat vs. wool production) rather than geographic origin. Results suggest several actionable items to improve in situ and ex situ conservation. The results clearly identify breeds in need of increased in situ and ex situ management (e.g., Hog Island and Karakul) and allow several suggestions for in situ management of flocks. Conversely, several of the breeds appear genetically similar and therefore require less emphasis on collecting germplasm samples for the gene bank. Commercially important breeds (e.g., Rambouillet and Suffolk) were found to have substantial variation, which should enable breeders to proceed, unencumbered by genetic diversity concerns, with selection strategies that maximize profit.     

The molecular basis of the sparse fur mouse mutation

The ornithine transcarbamylase-deficient sparse fur mouse is an excellent model to study the most common human urea cycle disorder. The mutation has been well characterized by both biochemical and enzymological methods, but its exact nature has not been revealed. A single base substitution in the complementary DNA for ornithine transcarbamylase from the sparse fur mouse has been identified by means of a combination of two recently described techniques for rapid mutational analysis. This strategy is simpler than conventional complementary DNA library construction, screening, and sequencing, which has often been used to find a new mutation. The ornithine transcarbamylase gene in the sparse fur mouse contains a C to A transversion that alters a histidine residue to an asparagine residue at amino acid 117.