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2.
Tissa Senaratna Bryan D. McKersie Stephen R. Bowley 《In vitro cellular & developmental biology. Plant》1990,26(1):85-90
Summary The use of somatic embryos from cell culture systems in the clonal propagation of plants would be greatly facilitated if the
somatic embryos could be dried and stored in a dormant state similar to true seeds. A cell culture system was developed for
alfalfa (Medicago sativa L.) line RL34 which gave high yields of somatic embryos in an approximately synchronized pattern. These somatic embryos were
treated with abscisic acid (ABA) at the cotyledonary stage of development to induce desiccation tolerance. With no visual
preselection, approximately 60% of the dried embryos converted into plants upon reimbibition. When high quality embryos were
selected prior to drying, 90 to 100% conversion rates were observed. The timing of the application of ABA in terms of embryo
development was critical with an optimum being at cotyledonary stage spanning approximately 4 days; thus, synchronized embryo
development is required for optimal expression in bulk samples. The vigor of the seedlings from dried somatic embryos was
greater than those from embryos which had not been dried, but remained substantially lower than those from true seeds. 相似文献
3.
Water-Deficit Tolerance and Field Performance of Transgenic Alfalfa Overexpressing Superoxide Dismutase 总被引:29,自引:1,他引:28 下载免费PDF全文
Transgenic alfalfa (Medicago sativa) expressing Mn-superoxide dismutase cDNA tended to have reduced injury from water-deficit stress as determined by chlorophyll fluorescence, electrolyte leakage, and regrowth from crowns. A 3-year field trial indicated that yield and survival of transgenic plants were significantly improved, supporting the hypothesis that tolerance of oxidative stress is important in adaptation to field environments. 相似文献
4.
The trait for somatic embryogenesis is being introduced sexually into alfalfa (Medicago sativa) breeding populations to facilitate genetic transformation of this crop. Cocultivation experiments were conducted with an agronomically-improved embryogenic clone from one such population as well as with two other embryogenic clones, one of which was the source of the embryogenic trait in the breeding populations. Transgenic plants were produced from the agronomically-improved clone whereas none were produced from the other two clones. Among the 16 transgenic plants analyzed there was a range in both copy number and number of integration sites for the NPT-II gene; those plants regenerated after a prolonged selection phase in vitro generally had the highest numbers in both respects. There was no evidence of sectoral chimerism of the transgene in a subsample of transgenic plants analyzed by PCR. 相似文献
5.
The effects of acute ethanol feeding and of chronic benfluorex administration on the activities of some enzymes of glycerolipid synthesis in rat liver and adipose tissue. 下载免费PDF全文
P H Pritchard M Bowley S L Burditt J Cooling H P Glenny N Lawson R G Sturton D N Brindley 《The Biochemical journal》1977,166(3):639-642
Activation of adenylate cyclase in isolated rat liver plasma membranes by cholera toxin was demonstrated. The activation requires the presence of NAD+ and ATP and is irreversible. 相似文献
6.
Bowley KA Linley JE Robins GG Kopanati S Hunter M Sandle GI 《The Journal of steroid biochemistry and molecular biology》2007,104(1-2):45-52
Aldosterone produces rapid, non-genomic, inhibition of basolateral intermediate conductance K(+) (IK(Ca)) channels in human colonic crypt cells but the intracellular second messengers involved are unclear. We therefore evaluated the role of protein kinase C (PKC) in aldosterone's non-genomic inhibitory effect on basolateral IK(Ca) channels in crypt cells from normal human sigmoid colon. Patch clamp studies revealed that in cell-attached patches, IK(Ca) channel activity decreased progressively to 38+/-8% (P<0.001) of the basal value 10 min after the addition of 1 nmol/L aldosterone, and decreased further to 23+/-6% (P<0.02) of the basal value 5 min after increasing the aldosterone concentration to 10 nmol/L. Pre-incubation of crypts with 1 micromol/L chelerythrine chloride or 1 micromol/L G? 6976 (PKC inhibitors) prevented the inhibitory effect of aldosterone. Conversely, channel activity decreased to 60+/-9% (P<0.02) of the basal value 10 min after the addition of 500 nmol/L PMA (a PKC activator), whereas 4alpha-PMA (an inactive ester) had no effect. When aldosterone (10 nmol/L) and PMA were added together, IK(Ca) channel activity was inhibited to the same extent as with aldosterone alone. These results indicate that aldosterone's non-genomic inhibitory effect on the macroscopic basolateral K(+) conductance in human colonic crypts reflects PKC-mediated inhibition of IK(Ca) channels. 相似文献
7.
Manipulating freezing tolerance in transgenic plants 总被引:5,自引:0,他引:5
Winterhardiness is a composite of tolerances to freezing, desiccation, ice-encasement, flooding and diseases. From one point
of view, winterhardiness may not be easily manipulated by genetic engineering technology because many different genes are
involved in the tolerance of these diverse stresses. However, these various stresses have similarities. They promote formation
of activated forms of oxygen, promote membrane lipid and protein degradation, cause similar biophysical changes in membrane
structure, and culminate with increased leakage of cytoplasmic solutes and loss of cellular membrane functions. These similarities
led to the hypothesis that winter injury might be reduced in crop plants if their tolerance of oxidative stress was increased.
Towards that objective we created transgenic alfalfa (Medicago sativa L.) plants that overexpress either Mn-SOD or Fe-SOD cDNA (provided by Dirk Inzé, Universiteit Gent). Petiole explants were
transformed using Agrobacterium tumefaciens and plants were regenerated by somatic embryogenesis. The primary transgenic plants were screened using PCR (polymerase chain
reaction), Southern hybridization and native PAGE for SOD activity. Greenhouse and laboratory studies showed a minimal difference
in stress tolerance between the primary transgenic and non-transgenic plants. In the first field trial, four primary transgenic
plants expressing two forms of the Mn-SOD cDNA had greater survival after two winters than the non-transgenic RA3. Similar
results were obtained in a second field trial, comparing 18 independent transformants with Mn-SOD targeted to the mitochondria,
11 independent transformants with Mn-SOD targeted to the chloroplast and 39 independent transformants with Fe-SOD targeted
to the chloroplast, expressed in three different non-transgenic plants. The transgenic plants averaged over 25% higher survival
than the non-transgenic controls after one winter. There was no effect of subcellular targeting or SOD type on field survival,
but there was variation among independent transformants containing the same SOD construct. Activated oxygen therefore appears
to be one of the possible causes of winter injury, and it should be possible to reduce winter injury in transgenic plants
by constitutive overexpression of SOD. 相似文献
8.
Nicolette C Bishop Gary J Walker Lee A Bowley Kate F Evans Karen Molyneux Fiona A Wallace Alice C Smith 《Journal of applied physiology》2005,99(4):1327-1335
The effect of carbohydrate (CHO) ingestion on antigen- (rather than mitogen-) stimulated T-cell responses to prolonged, intensive exercise may give a more realistic insight into the effect of CHO on T-cell functional capacity and subsequent infection risk. This study investigated the effect of CHO ingestion during prolonged, intensive exercise on influenza- and tetanus toxoid-stimulated T-cell cytokine mRNA expression and proliferation. Mitogen- [phytohemagglutinin (PHA)] stimulated proliferation was assessed for comparison. Responses were assessed following exercise on consecutive mornings to determine any carryover effect. Fifteen male games players performed two exercise trials in a double-blind, randomized, crossover design. Each trial comprised 90 min of intensive, intermittent running on consecutive mornings, with either CHO (6.4% wt/vol) or placebo (PLA) beverage ingestion before, during, and after each bout of exercise. Postexercise CD3(+) cell counts were higher in PLA than CHO on both days (P < 0.05). Antigen-stimulated T-cell cytokine mRNA expression was unaffected by exercise or CHO ingestion. Before exercise on day 2, T-cell proliferative responses to PHA, influenza, and tetanus toxoid were higher in CHO than PLA by 99, 80, and 58%, respectively (P < 0.01 for PHA, P < 0.05 for influenza and tetanus toxoid). At 1 h postexercise on day 2, PHA-induced proliferation was 70% higher in CHO than PLA (P < 0.05), yet there were no differences between trials for antigen-induced proliferative responses. Therefore, mitogen-induced T-cell proliferation following strenuous exercise and CHO does not necessarily reflect responses to specific antigens and, consequently, may not provide a good model for the situation in vivo. 相似文献
9.
Ariagno Ronald L.; Glotzbach Steven F.; Baldwin Roger B.; Rector David M.; Bowley Susan M.; Moffat Robert J. 《Journal of applied physiology》1997,82(3):1008-1017
Ariagno, Ronald L., Steven F. Glotzbach, Roger B. Baldwin,David M. Rector, Susan M. Bowley, and Robert J. Moffat.Dew-point hygrometry system for measurement of evaporative waterloss in infants. J. Appl. Physiol.82(3): 1008-1017, 1997.Evaporation of water from the skin is animportant mechanism in thermal homeostasis. Resistance hygrometry, inwhich the water vapor pressure gradient above the skin surface iscalculated, has been the measurement method of choice in the majorityof pediatric investigations. However, resistance hygrometry isinfluenced by changes in ambient conditions such as relative humidity,surface temperature, and convection currents. We have developed aventilated capsule method that minimized these potential sources ofmeasurement error and that allowed second-by-second, long-term,continuous measurements of evaporative water loss in sleeping infants.Air with a controlled reference humidity (dew-point temperature = 0°C) is delivered to a small, lightweight skin capsule and mixedwith the vapor on the surface of the skin. The dew point of theresulting mixture is measured by using a chilled mirror dew-pointhygrometer. The system indicates leaks, is mobile, and is accuratewithin 2%, as determined by gravimetric calibration. Examples from arecording of a 13-wk-old full-term infant obtained by using the systemgive evaporative water loss rates of ~0.02mgH2O · cm2 · min1for normothermic baseline conditions and values up to 0.4 mgH2O · cm2 ·min1 when the subject wasbeing warmed. The system is effective for clinical investigations thatrequire dynamic measurements of water loss. 相似文献
10.
Drugs affecting the synthesis of glycerides and phospholipids in rat liver. The effects of clofibrate, halofenate, fenfluramine, amphetamine, cinchocaine, chlorpromazine, demethylimipramine, mepyramine and some of their derivatives. 下载免费PDF全文
The effects on glycerolipid synthesis of a series of compounds including many drugs were investigated in cell-free preparations and slices of rat liver. p-Chlorobenzoate, p-chlorophenoxyisobutyrate, halofenate, D-amphetamine, adrenaline, procaine and N-[2-(4-chloro-3-sulphamoylbenzoyloxy)ethyl]norfenfluramine had little inhibitory effect on any of the systems investigated. Two amphiphilic anions, clofenapate and 2-(p-chlorophenyl)-2-(m-trifluoromethylphenoxy)acetate, both inhibited glycerol phosphate acyltransferase and diacylglycerol acyltransferase at approx. 1.6 and 0.7 mm respectively. Clofenapate (1 mm) also inhibited the incorporation of glycerol into lipids by rat liver slices without altering the relative proportions of the different lipids synthesized. The amphilic amines, mepyramine, fenfluramine, norfenfluramine, hydroxyethylnorfenfluramine, N-(2-benzoyloxyethyl)norfenfluramine, cinchocaine, chlorpromazine and demethylimipramine inhibited phosphatidate phosphohydrolase by 50% at concentrations between 0.2 and 0.9 mm. The last four compounds inhibited glycerol phosphate acyltransferase by 50% at concentrations between 1 and 2.6 mm. None of the amines examined appeared to be an effective inhibitor of diacylglycerol acyltransferase. Norfenfluramine, hydroxyethylnorfenfluramine and N-(2-benzoyloxyethyl)norfenfluramine produced less inhibition of glycerol incorporation into total lipids than was observed with equimolar clofenapate. The major effect of these amines in liver slices was to inhibit triacylglycerol and phosphatidylcholine synthesis and to produce a marked accumulation of phosphatidate. The results are discussed in terms of the control of glycerolipid synthesis. They partly explain the observed effects of the various drugs on lipid metabolism. The possible use of these compounds as biochemical tools with which to investigate the reactions of glycerolipid synthesis is considered. 相似文献