Bacterial dry matter content and biomass estimations

Approximately 20% dry-matter content appears to be an accepted standard value for bacterial cells. We have found that the dry-matter content of bacteria may be more than twice as high as generally assumed. The main reason for the low estimates seems to be that proper corrections for intercellular water have not been made when estimating the wet weight of the cells. Using three different bacterial strains, we determined a dry-matter content of cells ranging from 31 to 57%, suggesting not only that the accepted standard value is much too low but also that it is far from standard. To convert bacterial biovolume into biomass (carbon content), we suggest that 0.22 g of C cm-3 should be used as a conversion factor.     

A new method for non-destructive measurement of biomass, growth rates, vertical biomass distribution and dry matter content based on digital image analysis

BACKGROUND AND AIMS: Biomass is an important trait in functional ecology and growth analysis. The typical methods for measuring biomass are destructive. Thus, they do not allow the development of individual plants to be followed and they require many individuals to be cultivated for repeated measurements. Non-destructive methods do not have these limitations. Here, a non-destructive method based on digital image analysis is presented, addressing not only above-ground fresh biomass (FBM) and oven-dried biomass (DBM), but also vertical biomass distribution as well as dry matter content (DMC) and growth rates. METHODS: Scaled digital images of the plants silhouettes were taken for 582 individuals of 27 grass species (Poaceae). Above-ground biomass and DMC were measured using destructive methods. With image analysis software Zeiss KS 300, the projected area and the proportion of greenish pixels were calculated, and generalized linear models (GLMs) were developed with destructively measured parameters as dependent variables and parameters derived from image analysis as independent variables. A bootstrap analysis was performed to assess the number of individuals required for re-calibration of the models. KEY RESULTS: The results of the developed models showed no systematic errors compared with traditionally measured values and explained most of their variance (R(2) > or = 0.85 for all models). The presented models can be directly applied to herbaceous grasses without further calibration. Applying the models to other growth forms might require a re-calibration which can be based on only 10-20 individuals for FBM or DMC and on 40-50 individuals for DBM. CONCLUSIONS: The methods presented are time and cost effective compared with traditional methods, especially if development or growth rates are to be measured repeatedly. Hence, they offer an alternative way of determining biomass, especially as they are non-destructive and address not only FBM and DBM, but also vertical biomass distribution and DMC.     

X-ray microanalytic method for measurement of dry matter and elemental content of individual bacteria.

A method for the determination of dry matter and elemental content of individual bacterial cells is described. The method is based on energy-dispersive X-ray microanalysis in a transmission electron microscope. A theory for area correction of intensity is developed. Escherichia coli in the late exponential phase of growth and early stationary phase (glucose limited) had an average dry matter content of 278 and 154 fg/cell, respectively. Of the elements detected, sodium, magnesium, phosphorus, sulphur, chlorine, potassium, and calcium together made up 15 to 17% of the dry matter content. A phosphorus content of 4.2 to 5.4% of the dry matter was found in these cells. Volume measurements of air-dried cells gave an average of 1.20 to 1.25 micron3. These results emphasize that dry matter content and elemental composition can be measured directly on single cells from complex microbial communities.     

Specific leaf area and dry matter content estimate thickness in laminar leaves

BACKGROUND AND AIMS: Leaf thickness plays an important role in leaf and plant functioning, and relates to a species' strategy of resource acquisition and use. As such, it has been widely used for screening purposes in crop science and community ecology. However, since its measurement is not straightforward, a number of estimates have been proposed. Here, the validity of the (SLA x LDMC)(-1) product is tested to estimate leaf thickness, where SLA is the specific leaf area (leaf area/dry mass) and LDMC is the leaf dry matter content (leaf dry mass/fresh mass). SLA and LDMC are two leaf traits that are both more easily measurable and often reported in the literature. METHODS: The relationship between leaf thickness (LT) and (SLA x LDMC)(-1) was tested in two analyses of covariance using 11 datasets (three original and eight published) for a total number of 1039 data points, corresponding to a wide range of growth forms growing in contrasted environments in four continents. KEY RESULTS AND CONCLUSIONS: The overall slope and intercept of the relationship were not significantly different from one and zero, respectively, and the residual standard error was 0.11. Only two of the eight datasets displayed a significant difference in the intercepts, and the only significant difference among the most represented growth forms was for trees. LT can therefore be estimated by (SLA x LDMC)(-1), allowing leaf thickness to be derived from easily and widely measured leaf traits.     

草原群落生物量和土壤有机质含量对改良措施的动态响应

基于1983年开始的改良恢复长期观测试验, 研究了在排除干扰的围封保护下, 不同恢复改良措施对内蒙古退化羊草(Leymus chinensis)草原群落地上生物量和土壤有机质含量动态变化过程的影响, 改良恢复措施包括浅耕翻、耙地和自然恢复。结果表明: (1)地上生物量在前期(1983-1991年)的动态变化特征为自然恢复处理显著低于浅耕翻处理, 耙地处理与其余两个处理没有显著差异。中期(1992-2006年)各处理之间无显著差异; 后期(2007-2014年)为自然恢复>耙地>浅耕翻, 且自然恢复与浅耕翻处理之间有显著差异。(2) 0-10 cm土壤有机质含量在前期的动态变化特征为浅耕翻>耙地>自然恢复, 且处理之间有显著差异, 自然恢复、浅耕翻、耙地处理相对1983年土壤有机质分别增加了21%、45%、37%; 中期和后期自然恢复处理显著大于浅耕翻处理, 耙地处理介于两个处理之间且与二者没有显著差异。中期自然恢复、浅耕翻、耙地处理有机质含量相对1983年分别增加了61%、46%、57%, 后期分别增加了67%、51%、62%。(3) 10-30 cm土壤有机质在前期浅耕翻>自然恢复>耙地, 且各处理之间有显著差异; 中期和后期各处理之间无显著差异。总之, 应依据恢复目标的不同, 选择不同的改良措施。在短时间尺度上, 浅耕翻有利于退化羊草草原生产力和土壤有机碳的快速恢复, 而长时间尺度上自然恢复和耙地的效益更明显。     

Dynamic responses of aboveground biomass and soil organic matter content to grassland restoration

基于1983年开始的改良恢复长期观测试验, 研究了在排除干扰的围封保护下, 不同恢复改良措施对内蒙古退化羊草(Leymus chinensis)草原群落地上生物量和土壤有机质含量动态变化过程的影响, 改良恢复措施包括浅耕翻、耙地和自然恢复。结果表明: (1)地上生物量在前期(1983-1991年)的动态变化特征为自然恢复处理显著低于浅耕翻处理, 耙地处理与其余两个处理没有显著差异。中期(1992-2006年)各处理之间无显著差异; 后期(2007-2014年)为自然恢复>耙地>浅耕翻, 且自然恢复与浅耕翻处理之间有显著差异。(2) 0-10 cm土壤有机质含量在前期的动态变化特征为浅耕翻>耙地>自然恢复, 且处理之间有显著差异, 自然恢复、浅耕翻、耙地处理相对1983年土壤有机质分别增加了21%、45%、37%; 中期和后期自然恢复处理显著大于浅耕翻处理, 耙地处理介于两个处理之间且与二者没有显著差异。中期自然恢复、浅耕翻、耙地处理有机质含量相对1983年分别增加了61%、46%、57%, 后期分别增加了67%、51%、62%。(3) 10-30 cm土壤有机质在前期浅耕翻>自然恢复>耙地, 且各处理之间有显著差异; 中期和后期各处理之间无显著差异。总之, 应依据恢复目标的不同, 选择不同的改良措施。在短时间尺度上, 浅耕翻有利于退化羊草草原生产力和土壤有机碳的快速恢复, 而长时间尺度上自然恢复和耙地的效益更明显。     

X-ray microanalytic method for measurement of dry matter and elemental content of individual bacteria

A method for the determination of dry matter and elemental content of individual bacterial cells is described. The method is based on energy-dispersive X-ray microanalysis in a transmission electron microscope. A theory for area correction of intensity is developed. Escherichia coli in the late exponential phase of growth and early stationary phase (glucose limited) had an average dry matter content of 278 and 154 fg/cell, respectively. Of the elements detected, sodium, magnesium, phosphorus, sulphur, chlorine, potassium, and calcium together made up 15 to 17% of the dry matter content. A phosphorus content of 4.2 to 5.4% of the dry matter was found in these cells. Volume measurements of air-dried cells gave an average of 1.20 to 1.25 micron3. These results emphasize that dry matter content and elemental composition can be measured directly on single cells from complex microbial communities.     

Specific leaf area and leaf dry matter content as alternative predictors of plant strategies

A key element of most recently proposed plant strategy schemes is an axis of resource capture, usage and availability. In the search for a simple, robust plant trait (or traits) that will allow plants to be located on this axis, specific leaf area is one of the leading contenders. Using a large new unpublished database, we examine the variability of specific leaf area and other leaf traits, the relationships between them, and their ability to predict position on the resource use axis. Specific leaf area is found to suffer from a number of drawbacks; it is both very variable between replicates and much influenced by leaf thickness. Leaf dry-matter content (sometimes referred to as tissue density) is much less variable, largely independent of leaf thickness and a better predictor of location on an axis of resource capture, usage and availability. However, it is not clear how useful dry matter content will be outside northwest Europe, and in particular in dry climates with many succulents.     

Leaf and shoot water content and leaf dry matter content of Mediterranean woody species with different post-fire regenerative strategies

BACKGROUND AND AIMS: Post-fire regeneration is a key process in Mediterranean shrubland dynamics, strongly determining the functional properties of the community. In this study, a test is carried out to determine whether there is co-variation between species regenerative types and functional attributes related to water use. METHODS: An analysis was made of the seasonal variations in leaf relative water content (RWC), leaf dry matter content (LDMC), leaf moisture (LM) and live fine fuel moisture (LFFM) in 30 woody species of a coastal shrubland, with different post-fire regenerative strategies (seeding, resprouting or both). KEY RESULTS: RWC results suggest that the studied resprouters have more efficient mechanisms to reduce water losses and maintain water supply between seasons. In contrast, seeders are more drought tolerant. LDMC is higher in resprouters over the course of the year, suggesting a more efficient conservation of nutrients. The weight of the phylogenetic constraint to understand differences between regenerative strategies tends to be important for LDMC, while it is not the case for variables such as RWC. CONCLUSIONS: Groups of species with different post-fire regenerative strategies (seeders and resprouters) have different functional traits related to water use. In addition to the role of phylogenetical constraints, these differences are also likely to be related to the respective life history characteristics. Therefore, the presence and abundance of species with different post-fire regenerative responses influence the functional properties of the communities.     

Seasonal variability of dry matter content and its relationship with shoot growth and nonstructural carbohydrates

This study assesses how different phases of shoot growth underlie seasonal change in leaf and stem dry matter content (LDMC and SDMC, respectively) of 12 woody Mediterranean species. The relationship between LDMC and nonstructural carbohydrate (NSC) concentrations is also explored and the seasonal vs interspecies variability of LDMC compared. LDMC, SDMC and shoot elongation rate (SER) were measured on a monthly basis for a minimum of 12 months. Bud growth rate (BGR) and NSC concentrations were also assessed in several of the study species. LDMC and SDMC decreased during shoot elongation in spring and increased in summer, showing a significant negative correlation with SER, but were unrelated to BGR. Half of the species analysed showed a positive relationship between LDMC and NSC. Seasonal fluctuations of LDMC within species were higher than interspecies differences, and species ranking was significantly affected by the month of sampling, except during winter months. Seasonal changes in LDMC and SDMC are mainly related to shoot elongation phenology, and NSC sink-source relationships between old and growing organs can explain this relationship in some species. Owing to the high seasonal variability in LDMC, it is recommended that samples for comparative purposes should be collected as close to the winter as possible.     

不同沙丘生境主要植物比叶面积和叶干物质含量的比较

研究了生长在不同沙丘生境中 (流动沙丘 ,半固定沙丘和固定沙丘 ) 2 0个植物种 (10个 1年生植物种和 10个多年生植物种 )的比叶面积 (SL A)和叶干物质含量 (L DMC)的变化 ,并且分析了各个沙丘生境的土壤养分特征。结果表明 ,各个植物种的平均 SL A和 L DMC在植物种之间差异显著 ;多数在两种或 3种沙丘生境均有分布的植物其 SL A在不同沙丘生境之间差异显著 ,但是仅有 6个植物种的 L DMC在不同沙丘生境之间表现出差异 (p<0 .0 5 )。与许多研究结果类似 ,1年生植物的 SL A显著大于多年生植物的 SL A,而且两者之间 L DMC存在一定的差异。 1年生植物 SL A和 L DMC之间相关性不显著 ,但多年生植物SL A和 L DMC之间呈显著负相关。综合所有 2 0个植物种可以发现 ,SL A增大时 ,L DMC有下降的趋势     

Twenty-four-hour rhythm in the mitotic activity and in the water and dry matter content of regenerating liver

Summary A twenty-four hour rhythm is described in the variations of mitotic activity, dry weight, and water content of the regenerating liver of mice hepatectomized about noon. These variables have their maximal value at the onset of the rest periods in the morning and their minimal values at the initiation of the body activity periods in the evening. The rhythm is well defined on the second day and is repeated on the third day on a higher level.We acknowledge the assistance of Mrs. R. Cavoura in performing the hepatectomies and that of Mrs. M. A. V. Albornoz in making the histologic slides.The present work was carried out with the help of grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and Liga Mendocina de Lucha contra el Cáncer.     

Effects of cadmium and kinetin on chlorophyll content,saccharides and dry matter accumulation in sunflower plants

Cadmium (Cd) and kinetin (Kin) significantly affected the growth and contents of chlorophyll (Chl) and of soluble and reserve (hydrolysable) saccharides in sunflower plants. Cd-treated plants had lower contents of Chl and soluble saccharides and produced less dry matter than control (Cd-untreated) plants. Chla stability to heat (CSI) increased at all Cd concentrations. The same was true for Chlb stability (0–10 μM Cd). Spraying sunflower shoots with Kin solutions counteracted the deleterious effects of Cd. Kin application enhanced the Chla andb contents, Chla/b ratio, content of soluble saccharides and dry matter, and to less extent Chl stability. The relative role of Kin in affecting the parameters tested (as indicated by η² values) was predominant while that of Cd was subsidiary except for Chla stability. The role of Cd×Kin interaction was dominant for hydrolysable saccharides. Hence spraying shoots of plants grown under increasing Cd concentration with Kin can partially alleviate inhibitory effects of cadmium.     

Specific leaf area estimation model building based on leaf dry matter content of Cunninghamia lanceolata

随着叶片功能性状研究的不断深入, 通过简单易测量的叶片指标, 同时探究植物生活史权衡对策和估算林分生产力的研究需求日益增长, 例如叶干质量比(LDMC)和比叶面积(SLA)的相互转换。杉木(Cunninghamia lanceolata)是亚热带重要的常绿针叶树种, 基于LDMC对杉木SLA进行估算, 能够为核算SLA提供途径, 为机理解释和生产估算构建连接途径, 为小区域到大尺度、精算到估算搭建桥梁。该研究在湖南会同和河南信阳两个杉木生长区, 对处于不同小生境(坡向、坡位和冠层深度)以及不同生活史(林龄和叶龄)的叶片进行抽样和采集, 通过测得不同叶龄的单叶LDMC和SLA, 初步探究在不同因子下两个性状值的分布差异, 进一步基于LDMC构建SLA估算模型并讨论以叶龄为差分因子对模型的影响。结果表明: 1)杉木SLA平均值为(103.15 ± 69.54) cm ²·g ^-1, LDMC为0.39 ± 0.11; 2)杉木LDMC和SLA可用非线性模型进行估算, 模型符合估算要求; 3)其中一年生叶的拟合效果最好, 老叶(大于二年生叶)的拟合优度较低, 老叶较低的SLA (52.28-75.74 cm ²·g ^-1)可能暗示LDMC的变化保持相对独立性。该研究基于杉木LDMC的SLA估算模型可信且有效, 且不同叶龄对LDMC和SLA的影响可能预示着杉木叶片的响应敏感性和生活史权衡策略。     

基于叶干质量比的杉木比叶面积估算模型的构建

随着叶片功能性状研究的不断深入, 通过简单易测量的叶片指标, 同时探究植物生活史权衡对策和估算林分生产力的研究需求日益增长, 例如叶干质量比(LDMC)和比叶面积(SLA)的相互转换。杉木(Cunninghamia lanceolata)是亚热带重要的常绿针叶树种, 基于LDMC对杉木SLA进行估算, 能够为核算SLA提供途径, 为机理解释和生产估算构建连接途径, 为小区域到大尺度、精算到估算搭建桥梁。该研究在湖南会同和河南信阳两个杉木生长区, 对处于不同小生境(坡向、坡位和冠层深度)以及不同生活史(林龄和叶龄)的叶片进行抽样和采集, 通过测得不同叶龄的单叶LDMC和SLA, 初步探究在不同因子下两个性状值的分布差异, 进一步基于LDMC构建SLA估算模型并讨论以叶龄为差分因子对模型的影响。结果表明: 1)杉木SLA平均值为(103.15 ± 69.54) cm ²·g ^-1, LDMC为0.39 ± 0.11; 2)杉木LDMC和SLA可用非线性模型进行估算, 模型符合估算要求; 3)其中一年生叶的拟合效果最好, 老叶(大于二年生叶)的拟合优度较低, 老叶较低的SLA (52.28-75.74 cm ²·g ^-1)可能暗示LDMC的变化保持相对独立性。该研究基于杉木LDMC的SLA估算模型可信且有效, 且不同叶龄对LDMC和SLA的影响可能预示着杉木叶片的响应敏感性和生活史权衡策略。