CO２浓度和温度升高对红桦根际微生物的影响

应用自控、封闭、独立的生长室系统,研究升高的大气CO_２浓度（环境CO_２浓度+350（±25）μmol•mol-1,EC）和温度（环境温度+2.0（±0.5）℃,ET）及其交互作用（ECT）对不同栽植密度条件下红桦根际土壤可培养微生物数量的影响。结果表明：（1）EC显著增加了高密度条件下根际细菌数量;在整个生长季中,最大的根际细菌数量增加出现在7月份;而EC对低密度处理的根际细菌数量影响不显著。除了5月和6月份,ET在其余月份均显著增加了根际细菌数量,但是与密度处理没有有意义的相关;ECT对高低密度处理的根际细菌数量均未产生有统计意义的影响。（2）EC对低密度条件下的根际放线菌数量有显著增加,而对高密度条件下的根际放线菌数量无显著影响;ET和ECT对高低密度条件下的根际放线菌数量均未产生有统计意义的影响。（3）EC和ET对高低密度条件下的根际真菌数量无显著增加,而ECT显著增加了根际真菌数量。     

复合群落土壤微生物和酶活性对大气CO2浓度和温度升高的响应

应用自控、封闭、独立的生长室系统,研究川西亚高山林线复合群落根际、非根际土壤微生物数量以及根际、非根际土壤酶活性对大气CO2浓度升高(环境CO2浓度+350(±25)μmol.mol-1,EC)和温度升高(环境温度+2.0(±0.5)℃,ET)及其两者同时升高(ECT)的响应。结果表明:(1)与对照(CK)相比,EC、ET和ECT处理能够增加土壤根际微生物数量,但不同微生物种类对EC、ET和ECT的反应有所差异。(2)不同种类的根际土壤酶对EC、ET和ECT的响应不同。(3)与CK相比,EC、ET和ECT的非根际土壤微生物数量以及非根际土壤酶活性均无显著提高。(4)EC、ET和ECT处理对复合群落土壤微生物总数的根际效应明显;除ET处理的转化酶为负根际效应,其余处理的过氧化氢酶,脲酶及转化酶均表现为正根际效应。     

CO2浓度和温度升高对红桦根际微生物的影响

应用自控、封闭、独立的生长室系统,研究升高的大气CO2浓度(环境CO2浓度 350(±25)μmol.mol-1,EC)和温度(环境温度 2.0(±0.5)℃,ET)及其交互作用(ECT)对不同栽植密度条件下红桦根际土壤可培养微生物数量的影响。结果表明:(1)EC显著增加了高密度条件下根际细菌数量;在整个生长季中,最大的根际细菌数量增加出现在7月份;而EC对低密度处理的根际细菌数量影响不显著。除了5月和6月份,ET在其余月份均显著增加了根际细菌数量,但是与密度处理没有有意义的相关;ECT对高低密度处理的根际细菌数量均未产生有统计意义的影响。(2)EC对低密度条件下的根际放线菌数量有显著增加,而对高密度条件下的根际放线菌数量无显著影响;ET和ECT对高低密度条件下的根际放线菌数量均未产生有统计意义的影响。(3)EC和ET对高低密度条件下的根际真菌数量无显著增加,而ECT显著增加了根际真菌数量。     

岷江冷杉根际土壤微生物对大气CO2浓度和温度升高的响应

应用自控、封闭、独立的生长室系统,研究了川西亚高山岷江冷杉根际土壤微生物数量对大气CO₂浓度升高 (环境CO₂浓度+350(±25)μmol·mol^-1,EC)和温度升高(环境温度+2.2(±0.5)℃,ET)及其CO₂浓度和温度同时升高 (ECT)的响应.结果表明,1)同对照(CK)相比,在6月、8月和10月,EC处理的根际细菌数量分别增加了35%、164%和312%,ET处理增加了30%、115%和209%,而EC和ET处理对根际放线菌和根际真菌数量影响不显著;ECT处理的根际放线菌数量分别增加了49%、50%和96%,根际真菌数量增加了151%、57%和48%,而ECT对根际细菌数量影响不显著.2)3种处理对非根际土壤微生物数量影响均不显著.3)在EC、ET和ECT处理下,微生物总数的根际效应明显,其R/S值分别为1.93、1.37和1.46(CK的R/S值为0.81).     

铜陵铜矿区凤丹根际和非根际土壤酶活性

对铜陵铜矿区凤丹根际和非根际土壤酶活性特征进行了研究.结果表明,凤丹根际土壤各种酶活性显著大于非根际土壤.凤丹非根际土壤过氧化氢酶、磷酸酶和脲酶活性能敏感地反映土壤重金属复合污染状况;根际环境对土壤酶活性的影响表现为: 磷酸酶＞脲酶＞过氧化氢酶＞蔗糖酶＞多酚氧化酶,影响率分别为131.562%、92.492%、87.557%、59.673%34.076%;土壤各种酶活性与重金属复合污染程度呈显著负相关,相关系数均-0.868以上,表现出重金属复合污染对土壤酶活性的抑制效应.凤丹可有效地改善土壤环境,提高土壤各种酶的活性.     

不同轮作模式对桔梗生长、根际土壤微生物及土壤酶活性的影响

为研究不同轮作模式对桔梗根际土壤微生物及土壤酶活性的影响,从土壤微生态角度探寻一种无公害防治桔梗连作障碍的方式,以二年生桔梗为试材,采用盆栽试验的方法,以桔梗-桔梗（JG-JG）为对照,研究了桔梗-北沙参（JG-SS）、桔梗-玉米（JG-YM）、桔梗-防风（JG-FF）和桔梗-牛膝（JG-NX）不同轮作模式下对桔梗生长及土壤微生物和土壤酶活性的影响,分析筛选出桔梗的最优轮作模式。研究发现,JG-YM和JG-NX轮作模式下桔梗各生物量指标均优于其他处理;通过不同轮作种植模式对桔梗根际土壤微生物数量的影响研究发现,JG-SS、JG-YM、JG-NX、JG-FF细菌数量高于桔梗连作处理;JG-YM和JG-FF整体放线菌数量变化高于桔梗连作处理;JG-YM和JG-NX真菌数量与桔梗连作处理相比增长最为缓慢。通过不同轮作种植模式对桔梗根际土壤酶活性的影响研究发现,JG-NX的脲酶、蔗糖酶和纤维素酶活性高于其他四种处理。通过测定不同轮作模式下的桔梗生物量、桔梗根际土壤微生物数量和土壤酶活性,表明桔梗与牛膝或玉米轮作种植能改善种植土壤环境,缓解桔梗的连作障碍,可为桔梗的规范化种植奠定基础。     

三峡库区消落带4种适生植物根际与非根际土壤养分与酶活性特征研究

三峡库区消落带植被修复过程中,物种的更替对库区土壤的地球化学循环产生潜在影响。以三峡库区忠县石宝寨汝溪河消落带植被修复示范基地165-170 m海拔段人工种植狗牙根、牛鞭草、落羽杉以及立柳根际与非根际土为试验对象,探究其根际与非根际土壤的养分含量及酶活性差异,以阐明不同物种的生长适应性及其根际养分利用策略,比较不同物种对库区土壤的营养改良作用。结果表明：（1）三峡库区消落带4种适生植物根系活动导致根际与非根际土壤养分因子以及土壤酶活性产生差异,不同物种的栽植均在一定程度上使库区土壤营养条件得以改善;（2）碳、氮两种元素在4种适生植物根际土壤中发生不同程度的富集,但磷素与钾素在不同物种根际与非根际土壤之间的变化不一致;（3）蔗糖酶、脲酶以及酸性磷酸酶在4种适生植物根际土中均表现出一定程度的根际正效应（R/S>1）,且狗牙根对3种土壤酶的根际活化效果最为明显,其根际效应分别高达2.39、1.89和2.7;（4）在植物根系的调控下,根际土中有机质与氮素、磷素以及钾素的相关性更为显著,而非根际土壤中,仅钾素与有效氮、有效磷呈显著负相关,其余各土壤养分因子之间均无显著相关性;（5）与落羽杉和立柳两木本植物相比,狗牙根与牛鞭草两草本植物根际具有更为合理的养分调节模式,对库区土壤的改良效果更好。     

毛苔草湿地土壤酶活性及活性有机碳组分对水分梯度的响应

通过设置的W1（15cm）、W2（-5cm）、W3（-5～5cm）、W4（淹没）4种水分梯度的毛苔草（Carex lasiocarpa）盆栽培养实验,研究了湿地土壤酶活性、微生物量碳（MBC）、可溶性有机碳（DOC）及毛苔草地上生物量对水分梯度的响应及土壤酶活性与MBC、DOC、地上生物量的关系。土壤酸性磷酸酶、蔗糖酶和脲酶活性随着土壤水分增加而降低,但过氧化氢酶活性随着土壤水分增加而增加。与持续淹水相比,于湿交替（W3）增加了土壤酸性磷酸酶、蔗糖酶、脲酶和过氧化氢酶活性。土壤微生物量碳（MBC）含量表现为W3〉W1〉W2〉W4,蔗糖酶、脲酶、过氧化氢酶活性与MBC呈显著正相关（P〈0．05）。土壤可溶性有机碳（DOC）含量表现为W4〉W1〉W3〉W2,脲酶和酸性磷酸酶活性与DOC呈极显著负相关（P〈0．01）。毛苔草地上生物量与土壤酶活性呈正相关,其中,蔗糖酶、过氧化氢酶、脲酶活性与毛苔草生长状况密切相关。     

套作棉根际与非根际土壤酶活性和养分的变化

在棉麦两熟双高产条件下研究了棉花根际与非根际土壤酶活性和养分含量的变化.结果表明,套作棉土壤脲酶、蔗糖酶、蛋白酶及过氧化氢酶活性随生育进程的变化趋势与单作棉表现一致,但整个生育期套作棉根际与非根际土壤各种酶活性均明显高于单作棉.套作棉根际与非根际土壤养分含量在麦棉共生期低于单作棉或差异较小,而在麦收后则显著高于单作棉.套作棉土壤养分含量随生育进程的变化趋势与单作棉大体相同,但一些养分的吸收高峰晚于单作棉.无论套作棉还是单作棉,根际土壤酶活性和养分含量高于非根际.土壤各养分含量与土壤脲酶、蔗糖酶和蛋白酶活性呈显著(P=0.0,n=32)或极显著(P=0.01,n=32)相关,与土壤过氧化氢酶活性相关不显著.     

荒漠草原区土壤粒径组成对柠条根际土壤微生物数量及酶活性的影响

柠条(Caragana korshinskii)是荒漠草原区主要的造林绿化树种,研究其根际土壤微生物和酶活性与不同土壤类型土壤粒径组成的关系有重要意义,然而土壤粒径对荒漠草原柠条根际土壤微生物数量和酶活性的影响知之甚少,探讨土壤颗粒组分与微生物数量、土壤酶活性之间的关系,以及土壤颗粒组成对荒漠草原区固沙灌木植物柠条根际土壤微生物数量及酶活性的影响,可为揭示荒漠草原土壤退化及生态修复提供参考。以宁夏荒漠草原区土壤粒径组成差异显著的灰钙土、红黏土、风沙土环境下栽植的柠条为研究对象,研究不同土壤颗粒组成对根际土壤微生物数量及酶活性的相互关系与影响。结果表明:土壤微生物的数量表现为细菌放线菌真菌。根际土壤中的细菌、真菌数量显著高于非根际,且在3种不同类型的土壤中随着细砂粒的增多,真菌和放线菌数量逐渐降低,而细菌数量呈先增大后减小的趋势;根际与非根际土壤的蔗糖酶、碱性磷酸酶及过氧化氢酶活性均呈现出灰钙土红黏土风沙土的趋势,红黏土根际土壤中的脲酶活性显著高于灰钙土与风沙土;除过氧化氢酶外,土壤酶活性表现为根际高于非根际,在3种不同类型的土壤中随着细砂含量的增加,土壤酶活性均呈递减趋势。土壤颗粒组成与微生物数量之间没有明显的相关性,而与土壤酶活性之间显著相关,土壤酶活性与黏粒、粉粒呈正相关,与细砂、中砂呈负相关关系,根际土壤中酶活性更高,能够为植物及微生物提供更多的营养。     

CO2浓度升高、增温和冬小麦种植对土壤酶活性的影响

研究农田土壤酶活性对CO₂浓度升高和增温的响应,可为气候变化背景下农田生态系统养分管理提供科学依据。本研究在人工模拟气候室进行盆栽控制试验,设置了4种气候情景,分别为对照(CK,CO₂浓度400 μmol·mol^-1+正常环境温度)、CO₂浓度升高(ECO₂,CO₂浓度800 μmol·mol^-1+正常环境温度)、增温(ET,CO₂浓度400 μmol·mol^-1+增温4 ℃)及CO₂浓度和温度均升高(ECO₂+T,CO₂浓度800 μmol·mol^-1+增温4 ℃),研究有、无冬小麦生长下β--葡萄糖苷酶(βG)、β-N-乙酰葡糖苷酶(NAG)、碱性磷酸单脂酶(ALP)和多酚氧化酶(PPO)4种土壤酶活性在冬小麦拔节期(JS)、开花期(AS)、灌浆期(FS)和成熟期(MS)对CO₂浓度升高和增温的响应。结果表明:无冬小麦生长下,ECO₂与CK间4种土壤酶活性差异不显著,而ET和ECO₂+T处理对4种土壤酶活性有显著抑制作用。有冬小麦生长条件下,与CK相比,ECO₂和ECO₂+T处理对4种土壤酶活性均无显著影响;ET处理对土壤ALP和PPO活性有显著影响;ECO₂+T与ET间4种土壤酶活性有显著差异,与ET相比,ECO₂+T处理的土壤βG活性在JS期显著增加,NAG活性在JS期显著降低,ALP活性在AS和FS期显著增加,PPO活性在JS期显著降低,而在AS期显著增加。CO₂浓度升高与增温的交互作用在有、无冬小麦生长下均对土壤NAG和ALP活性有显著影响;无冬小麦生长下,增温和试验时段的交互作用对4种土壤酶活性有显著影响,而在有冬小麦生长下,增温和生育期的交互作用仅对ALP和PPO活性有显著影响;CO₂浓度升高、增温与试验时段的交互作用在无冬小麦生长下对土壤βG、ALP和PPO活性有显著影响,而在有冬小麦生长下CO₂浓度升高、增温与生育期对土壤NAG、ALP和PPO活性有显著影响。冬小麦生长对土壤βG、NAG和ALP活性在前两个生育期(JS+AS期)表现为显著抑制作用,在后两个生育期(FS+MS期)表现为显著促进作用,对土壤PPO活性在全生育期均表现为显著抑制作用。总体上,CO₂浓度升高对冬小麦土壤酶活性的影响不显著,而CO₂浓度与温度均升高对冬小麦土壤酶活性的影响在不同生育期因土壤酶种类不同而不同;此外,有、无冬小麦条件下4种土壤酶活性对CO₂浓度升高与增温的交互作用响应程度不一。     

Effects of Elevated CO2 and Temperature on Biomass Growth and Allocation in a Boreal Bioenergy Crop (Phalaris arundinacea L.) from Young and Old Cultivations

An auto-controlled climate system was used to study how a boreal bioenergy crop (reed canary grass, Phalaris arundinacea L., hereafter RCG) responded to a warming climate and elevated CO₂. Over one growing season (April–September of 2009), RCG from young and old cultivations (3 years [3-year] and 10 years [10-year]) was grown in closed chambers under ambient conditions (CON), elevated CO₂ (EC, approximately 700 μmol?mol^?1), elevated temperature (ET, ambient + approximately 3 °C) and elevated temperature and CO₂ (ETC). The treatments were replicated four times. Throughout the growing season, the above-ground (leaf and stem biomass) and below-ground biomasses were measured six times, representing various developmental stages (early stages: the first three stages, and late stages: the last three stages). Compared to the growth observed under CON, EC enhanced RCG biomass growth over the whole growing season (p?<?0.05), whereas ET increased RCG biomass growth in early stages but decreased growth in late stages, regardless of the cultivation age. However, the negative effect of ET later in the growing season was partially mitigated by CO₂ enrichment. Compared to CON plants, the final total biomass was 18 % higher for 3-year plants and 8 % higher for 10-year plants grown under EC. In comparison, for 3-year and 10-year plants, the biomass was 5 and 3 % lower under ET and 7 and 4 % greater under ETC, respectively. Under EC, the below-ground growth contributed more to the total biomass growth compared to the above-ground portion. The opposite situation was observed under ET and ETC. The climate-related changes in biomass growth were smaller in the old cultivation than in the young cultivation due to the lower net assimilation rate and lower specific leaf area in the old cultivation plants.     

三峡库区不同林龄马尾松土壤养分与酶活性的关系

基于对三峡库区不同林龄马尾松林下土壤养分和酶活性的测定及典范对应分析,探讨了不同林龄马尾松林土壤养分、酶活性特征及其相互关系.结果表明:马尾松林0 ～ 20 cm土壤有机质、总氮、铵态氮和有效磷含量均表现出成熟林＞中龄林＞近熟林;随着林龄的增加,土壤转化酶活性先降低后增加,纤维素酶、多酚氧化酶活性逐渐降低,而脲酶和过氧化物酶活性先增加后降低.经典范对应分析,不同林分中主要土壤养分对酶活性的影响顺序为总氮＞有机质＞pH＞容重＞铵态氮＞有效磷,转化酶与土壤有机质、总氮、总磷呈显著正相关,过氧化物酶与有机质、总氮、总磷、容重呈显著负相关,土壤主要养分含量高,转化酶活性较高,过氧化物酶活性相对较低.转化酶、纤维素酶和过氧化物酶是评价土壤质量及肥力较好的生物学指标.     

Divergent terrestrial responses of soil N2O emissions to different levels of elevated CO2 and temperature

Understanding the responses of soil nitrous oxide (N₂O) emissions from terrestrial ecosystems to future CO₂ enrichment and warming is critical for the development of mitigation and adaptation policies. The effects of continuous increase in elevated CO₂ (EC) and elevated temperature (ET) on N₂O emissions are not fully known. We synthesized 209 measurements from 70 published studies and carried out a meta-analysis to examine individual and interactive effects of EC and ET on N₂O emissions from grasslands, croplands and forests. On average, a significant increase of 23% in N₂O emissions was observed under EC across all case studies. EC did not affect N₂O emissions from grasslands or forests, but significantly increased N₂O emissions in croplands by 38%. The extent of ET effects on N₂O emissions was nonsignificant and there was no significant difference in N₂O emission responses among these three terrestrial systems. ET only promoted N₂O emissions in forest by about 32% when ET was less than 2°C. The interactive effect of EC and ET on N₂O emissions was significantly synergistic, showing a greater increase than the sum of the effects caused by EC and ET alone. Our findings indicated that the combination of EC and ET substantially promoted soil N₂O and highlighted the urgent need to explore its mechanisms to better understand N₂O responses under future climate change.     

Multi-objective environment chamber system for studying plant responses to climate change

This paper describes the technical information and performance of a new multi-objective chamber system enabling the control of environmental variables (e.g., temperature, CO₂, air humidity, wind speed, and UV-B radiation) for understanding plant responses to climate change. Over a whole growing season, four different climate scenarios were evenly programmed into the system’s 16 chambers as ambient environment (AMB), elevated temperature (ET), elevated CO₂ concentration (EC) and elevated temperature and CO₂ concentration (ETC). Simultaneously, the chamber effects were assessed regarding the physiological responses and growth of a boreal perennial grass (reed canary grass, Phalaris arundinacea L.). During the growing season, the chamber system provided a wide variety of climatic conditions for air temperature (T _a), relative humidity (RH) and CO₂ concentration (C _a) in the AMB chambers following outside conditions. The target temperature (+3.5°C) was achieved to a good degree in the ET and ETC chambers, being on average 3.3°C and 3.7°C higher than ambient conditions, respectively. The target concentration of CO₂ (700 ppm) was also well achieved in the EC and ETC chambers, being on average 704 ppm and 703 ppm, respectively. The stable airflow condition inside all of the chambers provided a homogeneous distribution of gases and temperature. The decreases in RH and increases in vapour pressure deficit (VPD) in the elevated temperature chambers were also maintained at a low level. Chamber effects were observed, with some physiological and growth parameters of plants being significantly lower in the AMB chambers, compared to outside conditions. The plant growth was negatively affected by the reduced radiation inside the chambers.     

马尾松人工林土壤有机层和矿质土壤层酶活性随雨旱季的变化

土壤酶活性随雨旱季的变化特征对于深入理解人工林土壤物质循环具有重要意义。2014年6月至2017年4月,采用原位土柱培养方法,研究了长江上游低山丘陵区的马尾松人工林土壤有机层和矿质土壤层转化酶、脲酶和酸性磷酸酶活性随关键时期(雨季初期;雨季中期;雨季末期;旱季初期;旱季末期)的变化特征。结果表明：土壤有机层和矿质土壤层酶活性随关键时期的变化显著,总体表现为雨季高于旱季。土壤有机层转化酶和脲酶活性呈现逐年降低的趋势;矿质土壤层酸性磷酸酶活性呈现逐年增加的趋势。土壤有机层转化酶和酸性磷酸酶活性显著高于矿质土壤层。土壤有机层三种酶活性年际变化幅度及随关键时期的变化幅度均高于矿质土壤层。偏最小二乘分析(PLS)表明,土壤含水量、微生物量和底物含量对土壤酶活性具有显著影响,但其影响大小强烈取决于土壤层次和酶的种类。可见,马尾松人工林土壤有机层酶活性对环境因子变化的响应更敏感,而且驱动土壤有机层和矿质土壤层酶活性动态的主导因子也存在差异。     

模拟氮沉降增加条件下土壤团聚体对酶活性的影响

氮沉降增加改变了森林土壤生态系统物质输入,影响土壤生物及酶活性,而土壤团聚体内相对稳定的微域生境可能减弱或延缓土壤生物和酶对氮沉降增加的响应强度。以广东省东莞大岭山森林公园荷木人工林为研究对象,用模拟N沉降方法,分析了2011年12月到2012年11月一年内氮沉降增加条件下表层混合土壤和土壤团聚体内脲酶、蔗糖酶和酸性磷酸酶活性的变化及影响因素,旨在理解氮沉降增加条件下土壤团聚体对酶活性的影响。结果表明:氮沉降增加对表层混合土壤中脲酶和蔗糖酶的抑制作用不显著,而酸性磷酸酶受氮沉降显著影响,表现为低氮(50 kg N hm-2a-1)促进,高氮(300 kg N hm-2a-1)抑制的规律。表层土壤团聚体内脲酶活性随氮沉降增加而降低,N300处理显著低于对照;蔗糖酶和酸性磷酸酶活性随氮沉降增加先降低后增加,N100处理最低,分别比其他处理降低了6.46%—25.53%和42.33%—68.25%。试验区内各粒径土壤团聚体内酶活性高于混合土壤,且随团聚体粒径增加酶活性均为先增加后降低。不同粒径土壤团聚体的3种酶活性均以2—5 mm最高,但脲酶、酸性磷酸酶在各团聚体粒径间差异不显著,蔗糖酶活性2—5 mm显著高于5—8 mm。土壤酶相对活性指数和相对活性综合指数结果显示,超过85%的团聚体粒径内的相对酶活性指数大于1,而土壤酶相对活性综合指数均大于1。以上结果表明,氮沉降增加条件下土壤团聚体对其团聚体内的土壤酶活性有隔离保护作用,但其隔离保护效果与酶的种类和土壤团聚体粒径有关。     

Inhibition of protein kinase C by ether-linked lipids is not correlated with their antineoplastic activity on WEHI-3B and R6X-B15 cells.

To test the hypothesis that the action of antineoplastic ether-linked lipids in leukemic cells is associated with their ability to inhibit protein kinase C (PKC), we have compared the effects of two ether-linked lipids, 1-O-hexadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET16-OCH3-GPC) and 1-O-hexadecyl-2-O-methyl-sn-glycero-3-(S-beta-D-1'- thioglucopyranosyl)-sn-glycerol (ET16-OCH3-beta-thio-Glc), on two different leukemic cell lines (WEHI-3B and R6X-B15). ET16-OCH3-GPC killed WEHI-3B cells with an EC50 value of 2.5 microM, whereas it was far less effective against R6X-B15 cells (EC50 = 40 microM). In contrast, the beta anomer of ET16-OCH3-beta-thio-Glc did not kill either cell line at concentrations up to 40 microM. Both ET16-OCH3-GPC and ET16-OCH3-thio-Glc inhibited 12-O-tetradecanoylphorbol 12,13-dibutyrate (TPA)-induced PKC translocation in both WEHI-3B and R6X-B15 cells. When WEHI-3B cells were first exposed to TPA, and then to ET16-OCH3-GPC, no significant decrease in PKC activity in the particulate fraction was noticed. When, however, the cells were first exposed to ET16-OCH3-GPC and then to TPA, the enzyme activity in the particulate fraction was decreased by 20-30%. A phorbol dibutyrate binding assay showed that the decrease in membrane-associated PKC activity and the increase in cytosolic PKC activity did not result from impeded enzyme translocation. These results suggest that the similar PKC inhibitory potency of ET16-OCH3-GPC and ET16-OCH3-beta-thio-Glc: (a) is not correlated with the widely different cytotoxicities of these agents and (b) is probably due to interference with the binding of diacylglycerol/phosphatidylserine or TPA to PKC. Taken together, these results suggest that the ether-linked lipids compete with diacylglycerol/phosphatidylserine or TPA for binding sites on PKC required for enzyme activation.