The application of ultraviolet microscopy to the distribution of lignin in wood description and validity of the technique     

J. A. N. Scott  A. R. Procter  B. J. Fergus  D. A. I. Goring 《Wood Science and Technology》1969,3(1):73-92

A method has been developed for the determination of lignin distribution in the wood cell wall by ultraviolet microscopy. The method incorporates some important advances on previus applications of UV microscopy to the study of lignin distribution. Ultrathin cross-sections of wood are obtained by the sample preparation and sectioning techniques of electron microscopy. The specimens are examined in monochromatic ultraviolet light using quartz reflection optics. The microscope image is photographically recorded and the negative is subsequently subjected to densitometric analysis. Each stage of the analytical procedure has been critically assessed to determine its validity and limitations. The method is ideally suited to the study of the removal of lignin from the wood cell wall during cooking and possesses other important applications in wood technology.  相似文献   

Summary of papers presented at The Potato Conference held at the Western Regional Research Laboratory,October 17 and 18, 1949     

R. Kunkel  W. T. Penzer  Paul P. Logan  Ray Kueneman  W. A. Scott 《American Journal of Potato Research》1950,27(2):59-85

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Instability of PR toxin in blue cheese.     

P M Scott  S R Kanhere 《Journal of the Association of Official Analytical Chemists》1979,62(1):141-147

PR toxin was unstable in solvent extracts of blue cheese and in strongly acidic solutions. However, it was appreciably stable over a 2.5 hr period in moderately acidic methanol-water extracts (pH 2--3) of blue cheese. Using this extraction mixture, it was determined that PR toxin was not stable in blue cheese itself. PR toxin reacted with model neutral and basic amino acids and the formation of PR imine from PR toxin in the presence of blue cheese was demonstrated. While PR imine added to blue cheese could be recovered on analysis after 5 min, over a 2--5 day period it too was unstable in the cheese.  相似文献   

Unicellular algae as a food for turbot (Scophthalmus maximus L.) larvae — The importance of dietary long-chain polyunsaturated fatty acids     

A.P. Scott  C. Middleton 《Aquaculture (Amsterdam, Netherlands)》1979,18(3):227-240

The production of juvenile turbot in research and commercial practice still involves the use of live foods for the early larvae. The rotifer Brachionus plicatilis is used for the first few days followed by nauplii of the brine shrimp, Artemia salina. During this live food phase, the addition of live unicellular algae to the rearing tanks improves the growth and survival of the turbot larvae.Within 10 days of the start of feeding, large differences in growth rate become apparent depending on the presence or absence of particular algae. The use of Dunaliella tertiolecta in particular results in stunted growth and high mortalities. Evidence is presented in this paper that Dunaliella tertiolecta is not toxic, and that its failure to support turbot larval growth is probably due to a deficiency of long-chain polyunsaturated fatty acids. These compounds have been shown by other workers to be an essential dietary requirement in O-group turbot.  相似文献   

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river     

Anton T. Ibbotson  William D. Riley  William R.C. Beaumont  Alastair C. Cook  Mark J. Ives  Adrian C. Pinder  Luke J. Scott 《Ecology of Freshwater Fish》2013,22(1):73-81

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.  相似文献   

Developmental temperature stress and parental identity shape offspring burst swimming performance in sockeye salmon (Oncorhynchus nerka)     

Jenn M. Burt  Scott G. Hinch  David A. Patterson 《Ecology of Freshwater Fish》2012,21(2):176-188

Abstract – The persistent effects of embryonic temperature stress and individual parentage on fry swimming performance were examined in a cross‐fertilisation experiment using sockeye salmon (Oncorhynchus nerka). A fixed‐velocity test of burst swimming was used to assess the endurance capacity and behavioural performance of individual fry from 10 offspring families incubated at 12, 14 or 16 °C to hatch and then reared through yolk absorption and exogenous feeding stages in a common posthatch environment (average 6.9 °C). Fry burst swim time (BST) was influenced by an interaction between incubation temperature and family identity. Average BST was longer for fry from the 12 °C prehatch treatment compared to 14 and 16 °C, although differences were largely attributable to temperature effects on average fry size. Behavioural observations revealed that fish incubated at 16 °C performed more poorly, having a larger proportion of individuals that required stimulation to swim, fatigued more frequently or were classified as ‘nonswimmers’. Within all three incubation temperature treatments, mean BST varied significantly among offspring families, independent of fry mass and length. An interesting relationship was observed within the 16 °C treatment, whereby families with higher survivorship were characterised with lower mean BSTs. Collectively, these findings demonstrate that exposure to high temperatures in early sockeye salmon development can result in persistent, parentally mediated effects on fry performance. As such, these results provide important insight into how elevated temperature events during egg incubation may affect early life history selection processes and survival in stages beyond when the stressor is experienced.  相似文献   

Mechanisms responsible for high levels of permethrin resistance in the house fly     

Jeffrey G. Scott  George P. Georghiou 《Pest management science》1986,17(3):195-206

The mechanisms responsible for > 6000-fold permethrin resistance in a pyrethroid-selected strain of house fly, Learn-PyR, were investigated. Through electrophysiological, in vitro metabolism, in vivo penetration and synergism studies it was demonstrated that the resistance mechanisms consisted of enhanced metabolic detoxification via the mixed-function oxidase (MFO) system, target-site insensitivity and decreased cuticular penetration. The major resistance mechanism was the MFO-mediated detoxification. The elevated MFO activity was correlated with higher levels of cytochrome P-450, cytochrome b₅ and NADPH-cytochrome c reductase activity. The kinetics of the latter showed similar K_m but greater V_max values in the Learn-PyR than in the susceptible strain, suggesting that the elevated activity was due to an altered amount, but not an altered form, of the enzyme. The Learn-PyR strain showed widely varying levels of resistance to the pyrethroids tested. Comparison of the pyrethroid structures with the resistance ratios revealed that resistance was highest in the presence of an unsubstituted phenoxybenzyl alcohol moiety. Substitution or certain modifications of the alcohol moiety reduced the level of resistance. Structure of the acid moiety or the presence or absence of an a-CN group did not affect the resistance level. These results are discussed with reference to the resistance mechanisms present.  相似文献   

Retrospective study of clinical observations on insect hypersensitivity and response to immunotherapy in allergic dogs          下载免费PDF全文

Rothstein E  Miller WH  Scott DW  Mohammed HO 《The Canadian veterinary journal. La revue veterinaire canadienne》2001,42(5):361-363

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Ultrasonographic findings of urinary retention caused by a vaginal stricture following dystocia in a ewe     

Scott PR  Sargison ND  Wilson D 《The Veterinary record》2001,148(10):315-316

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Acquired pelvic nerve dysfunction associated with impotence and urinary incontinence in a Limousin bull     

Scott PR  Cameron J 《The Veterinary record》2001,149(12):363-364

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