The effect of roots and litter of Calamagrostis canadensis on root sucker regeneration of Populus tremuloides

Marsh reed grass (Calamagrostis canadensis (Michx.) Beauv.)is a common, highly competitive grass native to the boreal mixedwoodforest. This grass increases in abundance after clear-cut loggingbut little is known about its effects on trembling aspen (Populustremuloides Michx.) sucker regeneration. The effects of Calamagrostissod and its litter on aspen regeneration were studied in twoseparate greenhouse studies. Calamagrostis sod did not affectthe initiation of suckers, but resulted in 30 per cent fewersuckers emerging above the soil that were smaller and had 40per cent less leaf area. Calamagrostis litter had little effecton the initiation and number of emerged suckers; however, itdelayed emergence by 10 days. The physical barrier by rootsand litter of Calamagrostis reduced or delayed the expansionof suckers and therefore prolonged their dependence on rootreserves. By the time the suckers reached the surface, theyhad to compete for light with Calamagrostis shoots that hademerged a week earlier. This, coupled with low soil temperaturesassociated with Calamagrostis in other experiments, will significantlyreduce the number and growth of suckers. Any reduction and delayin sucker emergence will decrease aspen regeneration and productivitysince the growing season in the boreal forest region is short.     

The genus Hypericum--a valuable resource of anti-Staphylococcal leads

In the present study, extracts of 34 species and varieties of the genus Hypericum were screened for activity against a clinical isolate of methicillin-resistant Staphylococcus aureus, which in addition possessed a multidrug efflux mechanism conferring a high level of resistance to therapeutically useful antibiotics. Thirty-three of the 34 chloroform extracts showed significant activity in a disk diffusion assay, and five extracts had minimum inhibitory concentrations of 64 microg/ml, indicating that this genus has great potential to yield compounds with potent activity against multidrug-resistant bacteria.     

Cavernous sinus syndrome in a holstein bull

A 13‐month‐old Holstein bull was presented for right‐sided exophthalmos. Ophthalmologic examination noted that the animal was visual in both eyes, but that the right pupil was persistently dilated and very sluggish to constrict when stimulated with a bright light and that normal ocular motility was absent. Fundic examination of the right eye was normal as was a complete ophthalmologic examination of the left eye. Radiographs at presentation did not reveal the presence of sinusitis or other skull abnormalities. Initial treatment comprised intravenous antibiotics and anti‐inflammatories for orbital inflammation over a 14‐day period. There was no perceptible change in the appearance or neuro‐ophthalmologic examination of the right eye during hospitalization. The animal was discharged to the owner's care, but 3 weeks later was found recumbent with unilateral strabismus of the left eye and a fixed right pupil. Due to the inability to rise and rapid deterioration, humane euthanasia was performed, and a full postmortem examination, preceded by a MRI, was performed that identified abscesses extending bilaterally through the round foramina obliterating the cavernous sinus region, as well as abscessation of the right mandible, right trigeminal neuritis, right‐sided sinusitis, and right‐sided otitis media. Cavernous sinus syndrome should be considered in cattle with a combination of exophthalmos and neuro‐ophthalmologic abnormalities involving cranial nerves III, IV, V, and VI, whose branches are located within the cavernous sinus.     

In vitro and in vivo characteristics of bacterial phytases and their efficacy in broiler chickens

1. Three bacterial phytases derived from Bacillus, Escherichia coli or Klebsiella were compared with a phytase derived from Aspergillus niger in vitro and in vivo. 2. The in vitro results indicated that Aspergillus, E. coli and Klebsiella phytase displayed their activity optima in an acid pH range while Bacillus phytase did so in neutral pH. 3. The trials also revealed that only Bacillus phytase is more resistant to heat treatments, while E. coli and Klebsiella phytases are more stable against proteolytic inactivation. 4. In vivo phytases derived from Aspergillus, Bacillus, E. coli, Klebsiella or a combination of Bacillus and E. coli improved the utilisation of phosphorus (P balance) significantly to 0.54, 0.54, 0.55, 0.55 or 0.58, respectively, compared to 0.42 in the negative control. 5. The phytases used in this study seemed to be equally effective in improving P utilisation regardless of proposed intestinal site of activity. Combination of phytases acting in the gizzard with phytases acting in the intestine seems to be a promising way to further improving in vivo efficacy of phytases in poultry.     

The impact of encroachment and bankside development on the habitat complexity and supralittoral invertebrate communities of the Thames Estuary foreshore

1. The Thames Estuary has a long history of human habitation and industrial development, which has resulted in dramatic losses of foreshore habitat; those fragments of fringing habitats that remain are also under threat from potential encroachment onto the foreshore. This paper describes a survey that set out to document the structural complexity and invertebrate communities of 21 supralittoral sites along a 65 km section of the Thames foreshore, and to assess their conservation value. This is the first extensive survey of supralittoral habitats in an urbanized estuary. 2. Invertebrates were sampled from the supralittoral at each site and the habitat types and their structural complexity (including numbers of plant species) at each site were also documented. The relationships between habitat complexity and invertebrate communities were investigated by linear correlation and multivariate analyses. 3. There were significant positive correlations between the number of supralittoral invertebrate species, habitat complexity (measured as the number of complex habitats present) and the number of plant species at each site. 4. The community composition of supralittoral invertebrates was also related to habitat complexity, although this trend was only evident for species data aggregated to higher taxonomic groups, suggesting that chance may play a key role in the colonization of these fragmented habitats. 5. Based on species recorded, the conservation value of supralittoral sites was low; most taxa were widespread eurytopics and only one supralittoral site (Syon Park) contained a threatened species, the snail Perforatella rubiginosa. Copyright © 1999 John Wiley & Sons, Ltd.