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101.
Allozyme electrophoresis of four sibling parthenogenetic Caucasian rock lizards Darevskia unisexualis, D.uzzelli, D.sapphirina, and D.bendimahiensis found seven clones and five variable loci. The data supported the hypothesis that D.raddei and D.valentini are the parental species of all four parthenogens. Variation patterns in Darevskia were summarized. Species that originated from a single F1 typically consisted of one widespread clone with a few rare clones. Species with multiple origins displayed variation only
slightly higher than species with a single origin. This is contrary to other genera of parthenogenetic lizards, in which cases
massive clonal variations were observed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
102.
F. Bangerth 《Plant Growth Regulation》2000,31(1-2):43-59
Natural abscission of young fruit and its regulation by plant hormones isconsidered and compared to the generally accepted model of senescencetriggered abscission of, for example, leaves or mature fruit. It isconcluded that abscission of young fruit cannot be explained by this model.Alternatively, it is suggested that the senescence triggered initial step inthe classical abscission model should be replaced by a correlativelytriggered step. Polar basipetal IAA transport with its autostimulation andautoinhibition components is the main regulating signal in this correlativeacting system and replaces ethylene as the initial driving force from thesenescence triggered model.Results supporting this model are presented and tested against existingresults from the literature. Finally, this hypothesis is tested as a possibleexplanation of the mode of action of some thinning chemicals orbioregulators. It is speculated how a thinning chemical should be designedto function in a more reliable way, at least as far as its interference with the endogenous hormone system is concerned. 相似文献
103.
104.
M. A. Zambre J. De Clercq E. Vranová M. Van Montagu G. Angenon W. Dillen 《Plant cell reports》1998,17(8):626-630
Regeneration-competent callus of Phaseolus vulgaris and P. acutifolius was obtained from mature embryo explants on a medium containing thidiazuron and indole-3-acetic acid. For the P. vulgaris genotype Xan-159, regeneration was achieved from cotyledon explants, but not from embryonic axis explants. Both explants
could be used for the P. acutifolius genotype NI 574 but embryonic axes gave the best results. In-vitro-rooted plantlets of P. acutifolius could readily be established in the greenhouse. For P. vulgaris hardening problems with in-vitro-rooted plantlets could be overcome by means of in vitro grafting. The potential of the described
procedure for obtaining transgenic P. vulgaris plants is discussed.
Received: 31 July 1997 / Revision received: 9 September 1997 / Accepted: 22 December 1997 相似文献
105.
Eric Hanssen Suzanne Franc Robert Garrone 《Biology of the cell / under the auspices of the European Cell Biology Organization》1998,90(3):223-228
A central issue in the understanding of Marfan syndrome deals with the functional architecture of fibrillin-containing microfibrils. Fibrillin-rich microfibrils are long extracellular matrix fibrillar components exhibiting a 50 nm periodic beaded-structure with a width of around 20–25 nm after rotary shadowing and a 10–12 nm diameter when observed in ultra-thin sections. They are composed of fibrillin monomers more or less associated with many other components which are, for the most part, poorly characterized up to date. They are known to be elastic but few data have been accumulated to understand their properties. Atomic force microscopy (AFM) allowed us to morphologically differentiate fibrillin-rich microfibrils from other fibrillar components and to investigate the thin structure of these beaded filaments in their native state. They showed, in AFM, a periodic beaded structure ranging from 50 to 60 nm and a width of about 40 nm. The different sizes of fibrillin-containing microfibrils previously observed after rotary shadowing and in ultra-thin sections was resolved with our technique and is revealed to be 10 nm in diameter. Each beaded microfibril appears to be composed of heterogeneous beads connected by 2–3 arms. An orientation of the microfibrils has been shown, and allows us to propose a complementary model of microfibrillar monomer association. 相似文献
106.
107.
目的:比较上颌窦挤压内提升(OSFE)植骨与不植骨种植修复的临床效果。方法:选择上颌后牙区种植修复的35例患者,其剩余牙槽嵴高度(RBH)为4~8 mm,共植入43颗种植体。A组16例患者为植骨组,20个种植位点,牙槽骨可用骨高度平均(5.87±1.19)mm,植入人工骨粉后植入种植体;B组19例患者为不植骨组,23个种植位点,缺牙区牙槽骨可用骨高度平均(5.67±1.10)mm,上颌窦提升后直接植入种植体。6个月后行二期手术完成修复。采用临床检查、X线检查及视觉模拟评分法(visual analogue scale,VAS)进行效果评价。结果:两组病例的牙槽嵴高度差异比较无统计学意义。在平均约36.7个月的随访期内,A组种植体的存留率为100%(20/20),B组中有1枚种植体因咬合力过大及口腔卫生较差脱落,种植体的存留率为95.6%(22/23),两组病例的存留率比较无统计学差异。两组患者的VAS值比较亦相当。所有种植体骨结合良好,种植体周围软组织无炎症,种植义齿咀嚼功能良好。结论:在严格控制适应症、准确掌握种植技巧的前提下,RBH在4~8 mm之间的病例无需额外植入骨代替材料即可取得理想的修复效果,简化了手术的操作,减少了手术的风险和创伤,节省了手术的时间和费用,易被患者接受。 相似文献
108.
目的:对比选择性冠状静脉动脉化(SCVBG)搭桥治疗弥漫性右冠状动脉狭窄病变中选择乳内动脉和大隐静脉作为桥血管的治疗效果。方法:选择2008年10月到2014年10月在我院行SCVBG搭桥的84例患者资料,其中选择大隐静脉作为桥血管进行冠状静脉动脉化搭桥患者46例(大隐静脉桥组),选择乳内动脉作为桥血管进行冠状静脉动脉化搭桥患者38例(乳内动脉桥组)。随访记录两组患者的生存情况、近期复查超声心动图、冠状动脉CTA及心绞痛复发率。结果:乳内动脉桥组患者总生存率(100%)明显高于大隐静脉桥组(82.6%)(P0.05)。乳内动脉桥组患者桥血管和心中静脉通畅率(100%)明显大于大隐静脉桥组(54.35%)(P0.05)。两组患者左心室射血分数(LVEF)较治疗前明显增加,左心室舒张期末内径(LVEDD)较治疗前明显减小(P0.05)。治疗后,乳内动脉桥组患者心绞痛复发率明显小于大隐静脉桥组(P0.05)。结论:SCVBG搭桥治疗弥漫性右冠状动脉狭窄病变中,选择乳内动脉桥效果优于大隐静脉桥,能明显提高桥血管和心中静脉通畅率,降低心绞痛复发率。 相似文献
109.
110.
Competitive exclusion as a mode of action of a novel Bacillus cereus aquaculture biological agent 总被引:1,自引:0,他引:1
R. Lalloo G. Moonsamy S. Ramchuran J. Görgens N. Gardiner 《Letters in applied microbiology》2010,50(6):563-570
Aims: To determine the contribution of potential modes of action of a Bacillus cereus aquaculture biological control agent in inhibition of the fish pathogen, Aeromonas hydrophila. Methods and Results: When B. cereus was tested in plate well inhibition studies, no production of antimicrobial compounds was detected. Bacillus cereus had a high growth rate (0·96 h?1), whereas Aer. hydrophila concentration decreased by c. 70% in co‐culture experiments. In nutrient limitation studies, B. cereus had a significantly higher growth rate when cultured under glucose (P < 0·05) and iron (P < 0·01) limitation in comparison with Aer. hydrophila. Bacillus cereus glucose (0·30 g l?1 h?1) and iron (0·60 mg l?1 h?1) uptake rates were also significantly higher (P < 0·01) than the Aer. hydrophila glucose (0·14 g l?1 h?1) and iron (0·43 mg l?1 h?1) uptake rates. Iron uptake was facilitated by siderophore production shown in time profile studies where relative siderophore production was c. 60% through the late exponential and sporulation phases. Conclusions: Competitive exclusion by higher growth rate, competition for organic carbon and iron, facilitated by siderophore production, could be identified as mechanisms of pathogen growth inhibition by B. cereus. Significance and Impact of the Study: This study is the first elucidation of the mechanism of action of our novel B. cereus biological agent in growth attenuation of pathogenic Aer. hydrophila. This study enhances the application knowledge and attractiveness for adoption of B. cereus NRRL 100132 for exploitation in aquaculture. 相似文献