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1.
The Effects of Light and Gravity on the Horizontal Curvature of Roots of Gravitropic and Agravitropic Arabidopsis thaliana L 总被引:4,自引:2,他引:2
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Mirza JI 《Plant physiology》1987,83(1):118-120
In an attempt to study and distinguish the effects of light and gravity on the direction of horizontal root growth, wild-type and an agravitropic mutant of Arabidopsis thaliana L., aux-1 were examined. The mutant aux-1 seedling roots are agravitropic but do respond to light, thus allowing the effects of light and gravity on roots to be studied separately. It is shown that in addition to the recognized negative phototropic and positive gravitropic responses of the root, there are also horizontal curvatures (clockwise or counterclockwise) induced by both unilateral light and gravity. The effects of light and gravity in inducing the horizontal curvature of roots are synergistic when both act in the same direction, and are antagonistic when acting in opposite directions. The results indicate that light and gravity interact to determine the direction and magnitude of the horizontal curvature of roots. 相似文献
2.
Free radical damage to cultured porcine aortic endothelial cells and lung fibroblasts: Modulation by culture conditions 总被引:5,自引:0,他引:5
Clark T. Bishop Zermeena Mirza James D. Crapo Bruce A. Freeman 《In vitro cellular & developmental biology. Plant》1985,21(4):229-236
Summary Culture conditions modulating cell damage from xanthine plus xanthine oxidase-derived partially reduced oxygen species were
studied. Porcine thoracic aorta endothelial cells and porcine lung fibroblasts were maintained in monolayer culture. Cells
were prelabeled with51Cr before xanthine plus xanthine oxidase exposure. Endothelial cells showed 30 to 100% more lysis than fibroblasts and thus
seemed more sensitive to this oxidant stress. The effect of cell culture age, as indicated by population doubling level (PDL),
was examined. Response of low PDL endothelial cells and fibroblasts subjected to oxidant stress was compared with the response
of PDL 15 cells. Both low PDL endothelial cells and fibroblasts responded differently to the lytic effect of xanthine oxidase-derived
free radicals than did higher PDL cells. Specific activities of the antioxidant enzymes catalase, managanese superoxide dismutase,
copper-zinc superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured in both low
and high PDL fibroblasts and endothelial cells. Antioxidant enzyme specific activities could only partially explain the differences
in response to oxidant stress between fibroblasts and endothelial cells and between low and high PDL cells. Cell culture medium
composition modulated the rate of production, and relative proportions of xanthine plus xanthine oxidase-derived partially
reduced species of oxygen, i.e. superoxide, hydrogen peroxide, and hydroxyl radical. Serum content of medium was important
in modulating free radical generation; superoxide production rates decreased 32%, H2O2 became undetectable, and hydroxyl radical generation decreased 54% in the presence of 10% serum. The medium protein and iron
content also modulated free radical generation. The data suggest that cell culture media constituents, cell type, and cell
culture age greatly affect in vitro response of cells subjected to oxidant stress.
Research supported by American Lung Association Fellowship Training Grant and Research Training Grant, the R. J. Reynolds
Corporation, and National Institutes of Health Grants HL29784 and 1 HL 23805. 相似文献
3.
Intensity of photosynthesis and chlorophyll content as related to leaf age inNicotiana Sanderae hort
U r?zně starých list? v listové r??ici 90 a? 110 denních rostlin Nicotiana sanderae hort. byly sledovány rozdály v intensitě ?isté fotosynthesy a v obsahu chlorofylu (a + b). Ke stanovení intensity fotosynthesy bylo pou?ito dvou odli?ných metod, a to váhového stanovení p?ír?stku su?iny podle Barto?e, KubÍna a ?et-lÍka (1960) a gazometrického stanovení infra?erveným analyzátorem CO2. Nejvy??í intensitu fotosynthesy i nejvy??í obsah chlorofylu (vzhledem k plo?e listové) mají mladé, ale ji? dob?e rozvinuté listy, tj. t?etí a? ?tvrté od vrcholu (prvním listem se rozumí list o plo?e asi 20 cm2). Tyto listy nazýváme ?fotosyntheticky dospělými“. Listy nejmlad?í a zejména pak listy star?í mají intensitu fotosynthesy i obsah chlorofylu ni??í; u nejstar?ích list? je intensita fotosynthesy prakticky nulová. Intensita fotosynthesy i obsah chlorofylu se během vývoje mění: jejich momentální rozdíly u list? v genetické spirále jsou z?ejmě shodné s jejich změnami v ontogenesi listu. Pokles intensity fotosynthesy p?i stárnutí list? je rychlej?í ne? pokles obsahu chlorofylu. P?i ur?itém obsahu chlorofylu (tj. asi 2,25 a? 2,45 mg/dm2) klesá intensita ?isté fotosynthesy k nule. Intensita fotosynthesy je v lineárním vztahu k mno?ství chlorofylu (p?i p?epo?tu na plo?nou jednotku), a to nezávisle na poloze listu v genetické spirále. Obě pou?ité metody ke stanovení intensity fotosynthesy poskytly obdobné výsledky. 相似文献
4.
YOSHIKAZU NAKAMURA KIVOKATSU TANABE KOH.JI EGAWA 《The Journal of eukaryotic microbiology》1989,36(1):58S-60S
Pneumocystis carinii is a pathogen which, causes fatal pneumonia in patients with the acquired immune deficiency syndrome (AIDS). To facilitate the basic study of P. carinii , we have analyzed its major surface proteins by both immunochemical and biochemical methods. The major protein components of both cysts and trophozoites are a group of proteins called "P115" with apparent masses of 105–120 kd. It includes 6 isoelcclric variants. A monoclonal antibody raised against cysts recognizes all 6 variants and reacts with epitopes located in the cell wall indicating that P115 is an immunorcactive surface component. The isoelectric variants contain identical or closely related protein components and they are mannose-rich glycoproteins. The isoelectric variation may be due primarily to differences in glycosylation. The majority of sera from humans with diagnosed pneumocystosis that were tested reacted strongly with the P115 proteins. To develop probes for DNA diagnosis and to facilitate molecular studies, a genomic DNA library of P. carinii has been constructed. Some of these clones were used for DNA hybridization analysis of rat and human lungs. 相似文献
5.
溶液培养小麦幼苗转移至含Cd~(2 )的营养液中,根系乙烯产生较快地增加,约在12h达高峰,然后下降;ACC含量亦呈先升后降的趋势。未和Cd~(2 )溶液直接接触的地上部乙烯亦增加,至36h达高峰,此后急剧下降,而ACG和 MAGC含量持续上升。地上部乙烯的增加,主要是由通过根系运往地上部的镉直接作用的结果,不是根部合成ACG运往地上部后再产生的。电镜观察表明,地上部乙烯产生和ACC含量变化的时间进程,可以与镉进入叶细胞内的部位及其对细胞膜和细胞器的影响相联系。 相似文献
6.
固定化虫荧光素酶光纤传感器 总被引:1,自引:0,他引:1
固定化虫荧光素酶光纤传感器蔡谨,王顺光,杨歧生,吉鑫松(浙江大学化工系生化教研室,杭州310027;中国科学院上海生物化学研究所,200031)关键词虫荧光素酶,ATP,固定化酶,光纤生物传感器ATP是生物体内极为重要的能量物质。如何准确快速地定量A... 相似文献
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9.
Alycia C. R. Lackey Alyssa C. Murray Nadia A. Mirza Thomas H. Q. Powell 《Journal of evolutionary biology》2023,36(6):882-892
The pace of divergence and likelihood of speciation often depends on how and when different types of reproductive barriers evolve. Questions remain about how reproductive isolation evolves after initial divergence. We tested for the presence of sexual isolation (reduced mating between populations due to divergent mating preferences and traits) in Rhagoletis pomonella flies, a model system for incipient ecological speciation. We measured the strength of sexual isolation between two very recently diverged (~170 generations) sympatric populations, adapted to different host fruits (hawthorn and apple). We found that flies from both populations were more likely to mate within than between populations. Thus, sexual isolation may play an important role in reducing gene flow allowed by early-acting ecological barriers. We also tested how warmer temperatures predicted under climate change could alter sexual isolation and found that sexual isolation was markedly asymmetric under warmer temperatures – apple males and hawthorn females mated randomly while apple females and hawthorn males mated more within populations than between. Our findings provide a window into the early speciation process and the role of sexual isolation after initial ecological divergence, in addition to examining how environmental conditions could shape the likelihood of further divergence. 相似文献
10.
红细胞抗高血压因子降压作用的进一步研究 总被引:4,自引:0,他引:4
我们曾报道原发性高血压患者(EHS)红细胞抗高血压因子(AHF)具有缓慢而持久的降压作用。本工作表明,AHF对卒中易感型自发性高血压大鼠(SHRsp)还具有快速短暂的降压作用,注射AHF后10—30s,SHRsp收缩压从原水平的26.8±1.7kPa降至20.1±1.5kPa(P<0.001)。正常人和大鼠红细胞AHF的降压作用明显强于EHS和高血压大鼠AHF。此外我们还发现EHS血浆中存在升压物质。以上结果提示,AHF缺乏和升压物质含量相对较高可能是原发性高血压发病的一个重要原因。 相似文献