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1.
Growth and Osmotic Adjustment of Cultured Suspension Cells from Alternanthera philoxeroides (Mart.) Griseb After an Abrupt Increase in Salinity 总被引:2,自引:0,他引:2
BALAGTAS-BUROW GLORIA E.; MORONEY JAMES V.; LONGSTRETH DAVID J. 《Journal of experimental botany》1993,44(3):673-679
We have developed a cell suspension culture from alligator weed(Alternanthera philoxeroides [Mart.] Griseb), a C3 member ofthe Amaranthaceae. Intact plants of alligator weed can growat 400 mol m3 NaCl. Growth of alligator weed suspensionswas compared to growth of tobacco (Nicotiana tabacum L. cv.Wisconsin 38) suspensions after subculture to 200 mol m3NaCl. Fresh weight and cell density of salt-treated alligatorweed suspensions more than doubled by 7 d after subculture,but the fresh weight of salt-treated tobacco suspensions didnot double during the 21 d experiment. Correspondingly, cellviability dropped from about 90% to 77% in alligator weed andto 41% in tobacco, at 1 d after subculture to 200 mol m3NaCl. The symplastic volume of alligator weed cells declined36% by 2 h after subculture to 200 mol m3 NaCl, but cellcontents became iso-osmotic with the media at this point. Between2 h and 6 h there was a further decrease in osmotic potential,an increase in turgor potential and a partial recovery of symplasticvolume. Turgor potential was similar to that in control cellsby 24 h, indicating significant osmotic adjustment. Turgor potentialsremained similar in both treatments from 24 h through 21 d butthe average symplastic volume of salt-treated cells was 11 %less than in control cells. Therefore, alligator weed suspensioncells exhibit a rapid recovery of water balance and cell growthafter an abrupt and substantial increase in salinity. Key words: Cell culture, growth, osmotic adjustment, salinity, turgor potential 相似文献
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Response of grazing snails to phosphorus enrichment of modern stromatolitic microbial communities 总被引:1,自引:0,他引:1
JAMES J. ELSER JOHN H. SCHAMPEL MARCIA KYLE JAMES WATTS EVAN W. CARSON THOMAS E. DOWLING CAROL TANG PETER D. ROOPNARINE 《Freshwater Biology》2005,50(11):1826-1835
1. The effects of added phosphorus (P) on the growth, P and RNA : DNA contents, and survivorship of snails grazing on laminated microbial mats (living ‘stromatolites’) were examined in the Rio Mesquites at Cuatro Ciénegas, Mexico (total P, c. 0.60 μmol L?1) to test the hypothesis that strong P‐limitation of microautotroph growth produces a stoichiometric constraint on herbivores because of mineral P‐limitation. 2. In a 3‐week experiment performed in summer 2001, addition of phosphorus (+15 μmol L?1) resulted in a strong decline in stromatolite biomass C : P ratio from very high levels (c. 2300 : 1 by atoms) to moderate levels (c. 550 : 1). The endemic hydrobiid snail Mexithauma quadripaludium responded to P‐enrichment with elevated body P content and higher RNA : DNA ratios, especially for small animals likely to be actively growing. This positive response is consistent with the existence of a stoichiometric constraint on snail growth. 3. In a longer experiment (8 weeks) involving a more moderate P enrichment (+5 μmol L?1) in summer 2002, P enrichment reduced stromatolite C : P ratio from moderate values in control treatments (c. 750) to very low values (<100 : 1). Snails responded to stromatolite P‐enrichment with increased body P content but, in contrast to the first experiment, with lower RNA : DNA ratio, lower growth rates, and higher mortality. 4. These contrasting results suggest that both very high and very low biomass C : P ratios in stromatolites are detrimental to M. quadripaludium performance, leading us to hypothesise that these herbivores live on a ‘stoichiometric knife edge’. 相似文献
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JENNIFER A. FIKE ANDREA M. DRAUCH JAMES C. BEASLEY GUHA DHARMARAJAN OLIN E. RHODES 《Molecular ecology resources》2007,7(3):525-527
In order to complement ecological information with genetic data we isolated and characterized 14 polymorphic microsatellite markers from raccoons (Procyon lotor). Three multiplexed panels comprising the loci were developed and 29 individuals from a contiguous habitat patch in northern Indiana, USA were genotyped. The number of alleles per locus ranged from four to 18, and overall heterozygosities ranged from 0.31 to 1.00. One locus was identified as possibly being X‐linked, since males appeared to be hemizygous. Data generated using these markers will be used to further our understanding of small‐scale raccoon population dynamics in a highly fragmented landscape. 相似文献
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Abstract. Growth rates throughout an organ curving phototropically under continuous, unilateral while light were monitored by lime-lapse photography of cress hypocotyls marked into 1 mm sections by two rows of ion-exchange beads. Curvature resulted from an integrated sequence of changes in growth rate on each side of the organ, but the actual patterns of change and, therefore rales of curvature, differed within even this one species, depending upon the immediate pretreatment of the seedlings. Transference of seedlings from darkness to unilateral irradiation gave immediate growth inhibition on both sides of the organ. Curvature resulted from differential recovery of growth rate, being seen first on the shaded side, most prominently in the apical regions; only 2h after initial exposure to light did growth recover on the lit (lower) side. On the other hand, transfer of seedlings from omnilateral to unilateral irradiation of the same intensity resulted in simultaneous growth inhibition on the irradiated side and stimulated growth on the shaded side: this growth stimulation of the shaded side was greater than occurred in totally darkened control plants. 相似文献
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Abstract. The biological and taxonomic relationships of the braconid genera Cantharoctonus Viereck, Noserus Foerster, Pseudavga Tobias and Rhysipolis Foerster are briefly discussed and short diagnoses are given for each genus. Figures are provided of the type-species of each of the genera. Pachystigmus Hellén 1927 is a new synonym of Noserus Foerster, 1862. 相似文献
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DISTANCE DATA REVISITED 总被引:1,自引:0,他引:1
Abstract— Objections to my earlier demonstration, that the branch lengths of trees fitted to distance matrices have no physical interpretation, are shown to be ill-founded. In particular the contention of Felsenstein, that fitted lengths estimate expectations of amounts of change, is shown to lead to a paradox. A method is introduced for constructing multiple trees of optimal or near-optimal fit to distance data, and this is found to give better performance than previous methods. Most published trees based on distances have been poorly chosen. Consensus trees of several trees with near-optimal fit are found to be quite poorly resolved, and it appears that molecular distances seldom provide much useful information on phylogenetic relationships. 相似文献
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The Effect of Decreasing the External Salinity on the Primary Processes of Photosynthesis in Dunaliella tertiolecta 总被引:3,自引:0,他引:3
GILMOUR D. JAMES; HIPKINS MICHAEL F.; BONEY ARTHUR D. 《Journal of experimental botany》1984,35(1):28-35
The euryhaline unicellular green alga Dunaliella tertiolectalost intracellular glycerol when subjected to a decrease inexternal salinity. After the salinity was decreased, photosynthesiswas inhibited for at least the first 100 min, but dark oxygenuptake was transiently stimulated. The extent of the 519 nmfield-indicating absorption change induced by photosystem Ialone was inhibited by decreasing the salinity, but other photosyntheticparameters were largely unaffected. A comparison of these resultswith hypertonic stress indicated that although both stressesinhibit the overall process of photosynthesis, they do so bydifferent mechanisms. Resuspending the algal cells in distilledwater resulted in an inhibition of all the photosynthetic parametersmeasured. Key words: Dunaliella, Photosynthesis, Hypotonicity 相似文献