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11.
WE have found that several different forms of choline acetyl-transferase (ChAc) from rat brain can be separated by isoelectric focusing. Such heterogeneity of ChAc is of particular interest in the context of its ultrastructural localization. Subcellular fractionation1–4 and histochemistry5 have shown that the enzyme in rat, in conditions of low ionic strength and pH, adhered to several different membranous structures. 相似文献
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Nils A. Øristland 《Bulletin of mathematical biology》1990,52(5):643-655
A computer model of body mass and composition in relation to gross energy balance is constructed. The model is built using
conventional empirical physiological formulae rather than statistical or analytical mathematical techniques. The model is
applied to the Minnesota and other experiments and produces as good or better simulations of observed values of changes in
body weight than reported for other formulae or models. Alternative physiological mechanisms concerning metabolic adaptions
to starvation, changes in time activity budgets and the energy equivalents of weight loss offer equally good simulations of
experimental results. The present analysis highlights the survival value of a basal metabolic depression during starvation
and indicates an optimal body composition of 10% mobilizable fat for starvation survival for a 70 kg man. Proper quantification
of the effects of the physiological mechanisms involved depends on new experimental data, however. Long term continuous monitoring
of time activity budgets are a necessary part of such experiments. 相似文献
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Norway was requested by the International Whaling Commission (IWC) to explore the use of high-velocity projectiles to replace cold harpoon as killing device for minke whales (Anon 1980). Tests of suitable high-velocity projectiles for minke whales were therefore initiated in 1982 as part of a wider project with the purpose of studying alternative killing methods to the traditional cold harpoon used in the Norwegian minke whale hunt until 1984 (Øen 1995). The results of the trials have previously been presented in unpublished reports to the IWC (Øen 1982, 1983, 1992). 相似文献
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High-density algal photobioreactors using light-emitting diodes 总被引:1,自引:0,他引:1
Lack of high-density algal photobioreactors (PBR) has been a limitation in exploiting the biotechnological potential of algae. Recent developments of highly efficient light-emitting diodes (LED using gallium aluminum arsenide chips) have made the development of a small LED-based PBR possible. We have calculated theoretical values of gas mass transfer requirements and light-intensity requirement to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. A prototype PBR has been designed based on these calculations. A cell concentration of more than 2 x 10(9) cells/mL (more than 6.6% v%sol;v), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/L culture/h were achieved using on-line ultrafiltration to periodically provide fresh medium. (c) 1994 John Wiley & Sons, Inc. 相似文献
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M. M. H. Kristensen J. I. Find F. Floto J. D. MØller J. V. NØrgaard P. Krogstrup 《Protoplasma》1994,182(1-2):65-70
Summary The development of somatic embryos in an embryogenic suspension culture ofPicea sitchensis was followed every day for two weeks after thawing from liquid nitrogen (LN2). Only a few cells, primarily located at the periphery of the embryonic region of the embryos, survived cryopreservation in LN2. Surviving cells were classified into two groups: embryogenic cells (EC) and non-embryogenic cells (NEC), based on their morphology and embryogenic competence. The dense cytoplasmic EC underwent organized growth and differentiation with first divisions occurring after 24 h, and embryo formation 6–8 days after thawing from LN2. No evidence of asymmetrical divisions or free-nuclear stages was found during somatic embryo formation. NEC had less dense cytoplasm with numerous small vacuoles. One to five days after thawing the NEC became progressively more vacuolated and elongated. Histological examination revealed no mitotic activity in NEC, and six days after thawing NECs were seen as single cells or unorganized cell aggregates. Two weeks after thawing the appearance of the cryopreserved cultures was comparable to that of the untreated cultures.Abbreviations EC
embryogenic cells
- ECC
embryogenic cell clusters
- FDA
fluorescein diacetate
- GMA
glycol methacrylate
- LN2
liquid nitrogen (–196°C)
- NEC
non-embryogenic cells 相似文献
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