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61.
In a previous study, using experimental metapopulations of the flour beetle, Tribolium castaneum, we investigated phase III of Wright's shifting balance process (Wade and Griesemer 1998). We experimentally modeled migration of varying amounts from demes of high mean fitness into demes of lower mean fitness (as in Wright's characterization of phase III) as well as the reciprocal (the opposite of phase III). We estimated the meta-populational heritability for this level of selection by regression of offspring deme means on the weighted parental deme means.Here we develop a Punnett Square representation of the inheritance of the group mean to place our empirical findings in a conceptual context similar to Mendelian inheritance of individual traits. The comparison of Punnett Squares for individual and group inheritance shows how the latter concept can be rigorously defined and extended despite the lack of explicitly formulated, simple Mendelian laws of inheritance at the group level. Whereas Wright's phase III combines both interdemic selection and meta-populational inheritance, our formulation separates the issue of meta-populational heritability from that of interdemic selection. We use this conceptual context to discuss the controversies over the levels of selection and the units of inheritance.  相似文献   
62.
 Interleukin(IL)-2 is a T helper (Th) 1 type cytokine that has been shown to play an important role in antitumour immune responses. In this study, the prognostic significance of serum IL-2 levels was investigated in 60 advanced non-small-cell lung cancer (NSCLC) patients. IL-2 serum levels were determined before chemotherapy, at the end of chemotherapy and during follow-up, using a commercially available enzyme-linked immunoadsorbent assay kit. The results were analysed according to the response to therapy and were used to generate a model predicting overall survival and time to treatment failure. All 60 patients were shown to have higher IL-2 serum levels than controls (P < 0.0001). Stage IV patients had significantly lower IL-2 levels than stage III patients (P < 0.0001), although they were still significantly higher than controls (P < 0.0001). It is interesting that, when patients were divided into responders and non-responders according to the response to therapy, the former were shown to have significantly higher pre-chemotherapy levels than the latter (P < 0.0001). Moreover, a further significant increase in IL-2 serum levels (P=0.004) and a significant decrease (P < 0.0001) were shown in responders and non-responders, respectively at the end of the therapy. Using univariate and multivariate analyses, both overall survival and time to treatment failure were shown to be affected by the mean pathological levels of IL-2. Furthermore, the prognostic significance of the serum level of IL-2 was confirmed by the stepwise regression analysis. In conclusion, determination of pre-treatment IL-2 serum levels was shown to be of independent prognostic utility in patients with advanced NSCLC; therefore, its possible use for prediction of outcome is proposed. Received: 16 March 2000 / Accepted: 27 July 2000  相似文献   
63.
Glutamine synthetase (GS, EC 6.3.1.2), a key enzyme in nitrogen assimilation, was investigated in tomato ( Lycopersicon esculentum Mill. cv. Hellfrucht Frühstamm) leaves infected with Pseudomonas syringae pv. tomato (Pst) or treated with the herbicide phosphinothricin (PPT), an irreversible inhibitor of GS. GS activity decreased markedly when Pst infection occurred in illuminated leaves, but only a slight decrease in relation to control leaves was observed under non‐photosynthetic conditions. In leaves treated with PPT, a rapid inhibition of GS activity was observed under all experimental conditions. When bacterial infection or herbicide treatment was carried out in the light, cytosolic GS (GS1) appeared as the predominant GS polypeptide; however, under non‐photosynthetic conditions GS2 remained the most abundant molecular GS species as occurs in non‐stressed plants. These results suggest a close correlation between the photosynthetic process and changes in the relative proportions of GS polypeptides during infection or herbicide treatment. Ammonium has been described as an inducer of GS genes, but as ammonium accumulated during all treatments, other light‐dependent factors could be involved in GS regulation of stressed leaves.  相似文献   
64.
微囊藻毒素在滇池鱼体内的积累水平及分布特征   总被引:2,自引:0,他引:2  
为了解富营养化水体中鱼体内微囊藻毒素(MC)的积累水平及其分布特征,2003年4月和9月份两次在滇池试验区采集了鲢、鳙和草鱼等鱼种,用ELISA方法对鱼体中肝、肾、空肠、胆、肌肉等不同组织中MC的含量进行了检测。结果表明,MC在所有样品中均能检测到,且主要分布在鱼体的肝肾脏和消化道等器官,而肌肉和非消化道器官中毒素含量相对较低。不同鱼种不同组织对MC的富集程度也明显不同,鲢鳙中肝脏和肾脏这两个主要的靶器官对MC的蓄积能力就远高于草鱼。同时,不同季节MC在鱼体内的积累水平也明显不同,4月份鱼样中MC的含量普遍低于9月份鱼样中MC的含量。最后按照WHO生活饮用水安全标准的建议进行推算,所有鱼肉中的MC均没有超过其推荐的人体每日可允许摄入量(≤0.04μg/kg人体重),初步推断鱼肉中MC暂时还未危及到人体健康,但仍具有潜在的风险性。  相似文献   
65.
A possible relationship between mitochondrial Mg2+ levels, structural configurations, and functional steady states has been studied in rat liver mitochondria. The results show that the concentration of mitochondrial Mg2+ in respiratory state 4 is definitely higher than in respiratory state 3. The metabolic transition from state 3 to state 4 and vice-versa is associated with reversible influx-efflux of about 10 nmol of Mg2+ per mg protein. The net uptake of this aliquot of Mg2+ is a necessary condition in order for the metabolic transition to state 4, both structurally and functionally, to occur. This process requires a threshold concentration of external Mg2+ greater than 5 mM. The phosphorylative mechanism does not appear to depend on the presence or absence of external Mg2+. The role of Mg2+ on the attainment and maintenance of the structural and functional steady state 4 seems to be correlated with its regulatory effect on the concentration of the mitochondrial Pi.  相似文献   
66.
E.tenella感染雏鸡特异性抗体的动态变化和母源免疫的研究   总被引:7,自引:1,他引:7  
本实验用斑点酶联免疫试验 (Dot ELISA)检测了E .tenella感染雏鸡特异性抗体、免疫母鸡卵黄和后代血清中特异性母源抗体的动态变化及不同日龄雏鸡的抗球虫水平。结果表明 :(1)雏鸡感染E .tenella后第 6d即可在循环血液中检测到特异性IgG ,于第 18天达到峰值 ,第 30天降至感染后第 7天时的水平。 (2 )母鸡二次免疫后第 5天卵黄中即有高水平的母源抗体 ,免疫母鸡后代 1日龄时母源抗体滴度高达 9.83,与未免疫对照组差异极显著 (P <0 .0 1) ,二者都随着日龄增长降低 ,但免疫组下降幅度很小 ,2 9日龄时仍和对照组 18日龄水平相当。 (3)免疫母鸡后代对再感染的抵抗力显著增强 ,卵囊减少率高达 93%,抗球虫指数和相对增重率都与对照组差异极显著 (P <0 .0 1) ,雏鸡的抗球虫水平随着日龄增长逐渐降低 ;母源抗体、抗球虫指数和相对增重率三者之间两两呈现明显的正相关 ,而这三者又都与卵囊产量呈明显的负相关。  相似文献   
67.
68.
地下水位对黄河三角洲柽柳根系生长的影响   总被引:1,自引:0,他引:1  
苏丽  董波涛  孙佳  赵西梅  吴春红  夏江宝 《生态学报》2021,41(10):3794-3804
为揭示黄河三角洲柽柳根系生长特征对地下水位的响应规律,明确柽柳生长适宜的地下水位,在咸水矿化度(6 g/L)下,模拟设置0、0.3、0.6、0.9、1.2、1.5、1.8 m共7个地下水位。测定分析栽植柽柳土柱的水盐参数与根系生长指标。结果表明:在咸水矿化度下,地下水位可显著影响土壤水盐变化,从而影响柽柳根系的生长。随地下水位的降低,土壤含水量、含盐量和土壤溶液绝对浓度显著降低。在高水位(≤0.6 m)下,柽柳根系生长受水盐胁迫影响显著,柽柳根长、根径、侧根数、总生物量、侧根生物量、根系连接长度均较低,拓扑结构呈叉状分支;中水位(0.9 m)时,土壤水盐条件适宜,柽柳侧根数、根径、二级侧根和毛细根生物量达到最大值,拓扑结构由叉状分支向鱼尾形分支过渡;低水位(≥1.2 m)下,土壤水盐含量低,柽柳根系总生物量、主根生物量、一级侧根生物量和根系平均连接长度在1.2 m水位达到最大值后降低,拓扑结构呈鱼尾形分支。柽柳根系生长与地下水位密切相关,柽柳通过改变根系生长和调整构型来适应不同土壤水盐和地下水位条件。高水位(≤0.6 m)下柽柳以降低根系生长深度,增加分叉,调配各组织器官的生物量来适应水盐胁迫;中水位0.9 m下土壤水盐条件最适宜柽柳生长;低水位(≥1.2 m)下柽柳主要受土壤干旱胁迫而使根系向下生长,增加根系连接长度,以此扩大资源获取效率。柽柳根系生长及根系构型对咸水矿化度下不同地下水位表现出较强的适应性和可塑性。  相似文献   
69.
External ATP enhanced stomatal opening of Commelina communis L. differently from EDTA. ATP was more effective in opening stomata than EDTA, when both were applied in amounts yielding equivalent free Ca2+ concentration. The stimulation by ATP depended upon its de-phosphorylation and was not due to the P1 released. Hence an energetical contribution of external ATP appears possible. Increase in CO2 concentration increased the stimulation of stomatal opening by ATP and diminished the internal ATP level, ATP/(ADP+AMP) ratio and respiration rate.  相似文献   
70.
目的:探讨联合检测血清胸苷激酶1(TK1)与乳酸脱氢酶(LDH)水平在非霍奇金淋巴瘤(NHL)患者鉴别诊断及疗效监测中的临床意义。方法:收集2016年1月至2018年6月我院诊治的111例非霍奇金淋巴瘤的初诊患者血清标本,并选择50例正常人血清标本作为对照,采用免疫印迹增强发光法检测TK1浓度,比色法检测LDH浓度。所有患者随访至少1年,分析和比较惰性NHL与侵袭性NHL及各自四类分期之间血清TK1和LDH水平的差异,化疗后完全缓解、部分缓解与未缓解组LDH水平以及NHL患者中血清TK1和LDH的阳性率。结果:高度侵袭性NHL患者和侵袭性NHL患者血清TKI和LDH水平与惰性NHL患者相比显著增高(P0.05),但惰性NHL患者血清TK1和LDH水平与正常组之间差异无统计学意义(P0.05);Ⅲ、Ⅳ期侵袭性NHL患者血清TK1和LDH水平与Ⅰ、Ⅱ期患者相比显著增高(P0.05)。与化疗前相比,四次化疗后,完全缓解组NHL患者血清LDH水平下降21.05%,部分缓解组为16.66%,病情稳定组血清LDH水平升高至11.54%,三组NHL患者血清LDH水平比较差异具有统计学意义(P0.008),两组之间的差异均有统计学意义(P0.05)。结论:联合检测血清TK1和LDH水平对于NHL患者的鉴别诊断、疗效评估均具有重要参考价值。  相似文献   
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