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11.
12.
Clerosterol-[26-14C], a 24β-ethyl-25-methylene sterol [(24S)-24-ethylcholesta-5,25-dien-3β-ol], was incorporated into clionasterol and poriferasterol by cultures of the green algae Trebouxia sp. 213/3 and Trebouxia sp. 219/2. Degradation of the labelled poriferasterol showed that the 14C retained its identity and was not incorporated as a result of metabolism of the clerosterol-[26-14C] and randomisation of label. These results are consistent with the proposed production, and subsequent reduction, of a 24β-ethyl-25-methylene intermediate in 24β-ethyl sterol biosynthesis in algae of the order Chlorococcales. 相似文献
13.
Trevor Robinson 《Phytochemistry》1978,17(11):1903-1905
Isotopic tracer experiments confirmed that glycerol and succinic acid are good precursors of the pyridine ring of ricinine in castor bean plants. Tritium from C-2 was lost from tritiated glycerol while tritium from C-1 was retained. Thus a derivative of dihydroxyacetone is likely to be intermediate. By simultaneous feeding of glycerol-1-(3)-[3H] and succinic acid-2(3)-[14C], it was hoped to find precursors of ricinine containing both labels, but none could be found. There was no evidence for the appearance of labeled quinolinic acid, which is presumed to be a precursor of ricinine. 相似文献
14.
Trevor Lipscombe 《Journal of biological physics》1992,18(4):297-306
The effect of turbulent fluid motion on the diffusion of simple organisms is discussed. The net reproduction rate and the turbulent flow are assumed to be Gaussian-correlated random variables. For homogeneous istropic turbulence, simple equations for the average concentration of the organisms are derived in terms of the energy density of the fluid. It is shown that the effective diffusivity generated by the motion is positive-definite, and is independent of the helicity of the flow. 相似文献
15.
Porphyrins and corrins have been immobilized onto solid-phase supports and used to dehalogenate organohalides under reducing conditions. One such system has been used to dehalogenate an aqueous solution (10 ppm) of lindane for over 90 days at over 98% efficiency and for a further 150 days in excess of 65% efficiency. Dichloromethane has been shown to be effectively dehalogenated when supplied to immobilized systems in gaseous form.
Correspondence to: T. S. Marks 相似文献
16.
David I. Dunstan Debbie P. Lashta Susan I. Kikcio Trevor A. Thorpe 《In vitro cellular & developmental biology. Plant》1992,28(1):33-38
Summary The effects of sucrose concentration, addition of ammonium nitrate, and exposure to N6-benzyl-adenine (BA) on multiplication potential with shoots derived from shoot cultures of 17- to 20-yr-old Douglas fir trees
[Pseudotsuga menziesii (Mirb.) Franco] were compared. Each of these conditions, when compared independently, affected recurrent shoot multiplication
and influenced shoot development, as measured by the abundance of shoot apices. Sucrose concentration was influential, the
use of 25 g · liter−1 providing twice the multiplication obtained with 20 g · liter−1, and 14 × that obtained with the 30 g · liter−1 concentration routinely used (tree 11). Ammonium nitrate usage also improved multiplication, a 2.5 times improvement being
obtained after incorporation of 100 mg · liter−1 NH4NO3 into the medium (tree 33). Shoot cultures were responsive but relatively sensitive to addition of BA, the best improvement
in multiplication (5 times) being obtained with brief exposures to 3 mg · liter−1 BA (tree 11). Although shoot cultures were responsive to the conditions investigated, differences in shoot multiplication
and development were not displayed for several weeks. It was not possible therefore to repeat all the treatments with more
than one genotype; however, when this was possible a genotype-dependent variation in response was evident. 相似文献
17.
The 14 and 18 S forms of acetylcholinesterase from the electric organ of Electrophorus electricus were purified by chromatography on an N-methyl-3-aminopyridinium derivative of Affi-Gel 202. a further increase in purity was seen when these forms were separated by density gradient sedimentation subsequent to the affinity step. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate demonstrated that the 14 and 18 S forms were highly purified following these procedures. Using [3H]diisopropyl fluorophosphate labeling and separation of labeled enzyme from unreacted [3H]diisopropyl fluorophosphate by gel filtration, active site numbers of 8.3 and 11.4 were determined for the 14 and 18 S forms, respectively. These numbers compare to 4.2 active sites determined for the 11.8 S globular form of acetylcholinesterase. These results are in accord with a proposed model of two and three tetrameric structures comprising the head groups of the 14 and 18 S forms of electric tissue acetylcholinesterase. 相似文献
18.
Trevor Lewis 《Mathematical biosciences》1976,30(3-4)
In a four-population model for schistosomiasis, the effect of the introduction of a trace of infection is considered. In particular, we are interested in whether the disease establishes itself or dies out quickly. Threshold results are presented for both the deterministic and the stochastic treatment of the model. 相似文献
19.
20.
David E. DeMik Michael C. Marinier Trevor R. Gulbrandsen Natalie A. Glass Jacob M. Elkins 《The Iowa orthopaedic journal》2022,42(1):163
BackgroundWhile muscle atrophy is a function of normal aging, loss of muscle in the setting of hip and knee osteoarthritis (OA) has been observed using radiographic studies. There is limited data available regarding changes in extremity composition using bioimpedance (BIA). The purpose of this study was to assess the changes in extremity composition in patients with isolated, unilateral hip or knee OA using BIA.MethodsPatients presenting to our institution’s adult reconstruction clinic from February 2020 to April 2021 were retrospectively reviewed to identify those with isolated, unilateral hip and knee OA. The InBody 770 Body Composition Analyzer (InBody USA, Cerritos, California) was used to perform a complete body composition assessment, per protocol. Lean extremity mass (LEM), fat mass (FM), intracellular water (ICW), extremity body water (EBW = ICW + extracellular water (ECW)) and phase angle (PA) were determined. Differences between the affected (OA) and unaffected (no OA) extremities were compared using t-tests.Results38 patients had isolated hip OA. The mean age was 60.8 (±11.7) years, mean BMI was 31.7 (±6.8) kg/m2, and 39.5% were female. LEM, FM, EBW, ICW, and PA were significantly decreased in the hip OA extremity (LEM: 20.0 vs. 20.4 kg, p=0.0008, FM: 8.8 vs. 8.9 kg, p=0.0049, EBW: 15.7 vs 16.0, p=0.0011, ICW: 9.5 vs. 9.7 L, p=0.0004, PA: 4.5 vs 4.9º, p<0.0001). There were 25 patients with isolated knee OA. Mean age was 62.8 (±11.3) years, mean BMI was 33.6 (±6.9) kg/m2, and 52.0% were female. FM and PA were significantly lower in the knee OA extremity (11.3 vs 11.4 kg, p=0.0291, 4.5 vs 4.9º, p<0.0001). There were no significant differences in LEM, EBW, and ICW between the knee OA extremity and the unaffected extremity.ConclusionPatients with isolated, unilateral hip OA had decreased LEM, FM, EBW, and ICW in the affected extremity. Both unilateral hip and knee OA was associated with decreased PA, suggestive of greater underlying dysfunction in muscle or cellular performance. Further study is needed to better define when these abnormalities develop, how they progress over time, and the impact of targeted interventions in reversing these changes. Level of Evidence: III 相似文献