| 1. |
- Malmberg, E, et al.
(författare)
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Microorganisms on toothbrushes at day-care centers.
- 1994
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Ingår i: Acta odontologica Scandinavica. - 0001-6357. ; 52:2, s. 93-8
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Tidskriftsartikel (refereegranskat)abstract
- The microflora on 44 toothbrushes at 4 day-care centers in the city of Göteborg have been investigated as a presumptive risk factor for transmission of microorganisms by children. Non-supervised toothbrushing without the use of toothpaste was performed at the day-care centers twice a day. Streptococci, predominantly S. salivarius, S. sanguis, and S. mitis, were the most frequently recorded group of microorganisms and generally constituted the greatest part of the flora (on average, 50%). Beta-hemolytic streptococci were not found in any sample. Haemophilus species were noted in 82% of the samples. H. parainfluenzae being the most frequent, and H. influenzae being identified in only one sample. Anaerobes constituted on average a third of the microflora. Staphylococci were identified in 86% of the samples, S. epidermidis dominating. Fungi including molds were found in 50% of the samples, and from one day-care center large numbers of enteric organisms were identified. Thus this study shows that unsupervised toothbrushing at day-care centers can be questioned, more from a general hygienic point of view than from the risk of transmitting serious pathogens.
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| 2. |
- Hurry, Vaughan, 1960-, et al.
(författare)
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Effects of a short-term shift to low-temperature and of long-term cold hardening on photosynthesis and ribulose-1,5-bisphosphate carboxylase oxygenase and sucrose-phosphate synthase activity in leabves of winter rye (Secale-Cereale L)
- 1994
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Ingår i: Plant Physiology. - 0032-0889 .- 1532-2548. ; 106:3, s. 983-990
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Tidskriftsartikel (refereegranskat)abstract
- The effect of a short-term (hours) shift to low temperature (5 degrees C) and long-term (months) cold hardening on photosynthesis and carbon metabolism was studied in winter rye (Secale cereale L. cv Musketeer), Cold-hardened plants grown at 5 degrees C exhibited 25% higher in situ CO2 exchange rates than nonhardened plants grown at 24 degrees C. Cold-hardened plants maintained these high rates throughout the day, in contrast to nonhardened plants, which showed a gradual decline in photosynthesis after 3 h. Associated with the increase in photosynthetic capacity following cold hardening was an increase in ribulose-1,5-bisphosphate carboxylase/oxygenase and sucrose phosphate synthase activity and 3- to 4-fold increases in the pools of associated metabolites. Leaves of nonhardened plants shifted overnight to 5 degrees C required 9 h in the light at 5 degrees C before maximum rates of photosynthesis were reached. The gradual increase in photosynthesis in leaves shifted to 5 degrees C was correlated with a sharp decline in the 3-phosphoglycerate/triose phosphate ratio and by an increase in the ribulose bisphosphate/3-phosphoglycerate ratio, indicating the gradual easing of aninorganic phosphate-mediated feedback inhibition on photo-synthesis. We suggest that the strong recovery of photosynthesis in winter rye following cold hardening indicates that the buildup of photosynthetic enzymes, as well as those involved in sucrose synthesis, is an adaptive response that enables these plants to maximize the production of sugars that have both cryoprotective and storage functions that are critical to the performance of these cultivars during over-wintering.
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| 3. |
- SUNDBLAD, LG, et al.
(författare)
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PREDICTION OF FROST HARDINESS IN SEEDLINGS OF SCOTS PINE (PINUS-SYLVESTRIS) USING MULTIVARIATE-ANALYSIS OF CHLOROPHYLL-A FLUORESCENCE AND LUMINESCENCE KINETICS
- 1990
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Ingår i: Canadian Journal of Forest Research. - : Canadian Science Publishing. - 0045-5067 .- 1208-6037. ; 20:5, s. 592-597
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Tidskriftsartikel (refereegranskat)abstract
- Seedlings of Scots pine (Pinussylvestris L.) were artificially frost hardened under controlled conditions. To follow the development of hardiness, the frost killing temperature was determined. Four levels of hardiness were defined during the course of frost hardening. After adaptation of the seedlings to dark conditions at room temperature, fluorescence induction and far red induced luminescence decay kinetics were recorded for seedlings of the four defined levels of hardiness. The induction curve of fluorescence and the decay curve of luminescence were digitized for 110 time intervals, and the values were used in a multivariate partial least squares analysis to evaluate the potential of luminescence and fluorescence as predictive probes for cold hardiness. The results showed that both fluorescence induction and luminescence decay kinetics contain information allowing the prediction of frost hardiness of artificially cold-hardened seedlings of Scots pine.
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