Biomass Values (biomass + value)

Distribution by Scientific Domains

Selected Abstracts

Development of a Method for the Quantification of the Molar Gold Concentration in Tumour Cells Exposed to Gold-Containing Drugs

CHEMMEDCHEM, Issue 5 2007
Ingo Ott Dr.
Abstract The knowledge of the cellular molar concentration of a drug is an extremely important parameter for the discussion and interpretation of its efficacy and bioavailability. Concerning metal complexes, electrothermal atomic absorption spectroscopy (ETAAS) offers a valuable analytical tool. However, matrix effects often hamper proper quantification of the metal concentration in biological tissues. This paper describes the development of an ETAAS method for the quantification of the molar gold concentration in HT-29 colon carcinoma cells. ETAAS analytical conditions were optimised and a factor was developed which allows the calculation of the molar cellular gold concentration from the measured gold per cellular biomass value. The method was used to quantify the gold content in HT-29 cells after exposure to the gold drug auranofin. Results indicated a strong cellular uptake of auranofin (compared to other metal anticancer drugs), which significantly correlated with the antiproliferative effects triggered by this agent. [source]

Ant colony size and the scaling of reproductive effort

J. Z. Shik
Summary 1Reproductive effort typically scales as mass075 in unitary organisms, but less is known about such scaling in colonial organisms. 2I compiled data on worker and reproductive number at maturity for 65 ant species and found an interspecific allometry (alate number = worker number073) whose exponent was significantly < 1, even after a phylogenetic correction. 3When I analyzed 15 species for which biomass data were available, I found an interspecific isometry (alate biomass = worker biomass089) whose exponent was not significantly different from 1. Analysis of maximum species biomass values, rather than averages, strengthened this isometry, yielding a slope b = 101 that was also not distinguishable from 1. 4Species with larger colony size at reproduction tended to couple investment in proportionately fewer alates with investment in larger male and female alates. 5This comparative analysis suggests a trade-off between alate size and number, and provides a framework for studying the diversity of colony life histories and the mechanisms generating allometries. [source]

Above-ground forest biomass is not consistently related to wood density in tropical forests

GLOBAL ECOLOGY, Issue 5 2009
James C. Stegen
ABSTRACT Aim, It is increasingly accepted that the mean wood density of trees within a forest is tightly coupled to above-ground forest biomass. It is unknown, however, if a positive relationship between forest biomass and mean community wood density is a general phenomenon across forests. Understanding spatial variation in biomass as a function of wood density both within and among forests is important for predicting changes in stored carbon in response to global change, and here we evaluated the generality of a positive biomass,wood density relationship within and among six tropical forests. Location, Costa Rica, Panama, Puerto Rico and Ecuador. Methods, Individual stem data, including diameter at breast height and spatial position, for six forest dynamics plots were merged with an extensive wood density database. Individual stem biomass values were calculated from these data using published statistical models. Total above ground biomass, total basal area and mean community wood density were also quantified across a range of subcommunity plot sizes within each forest. Results, Among forests, biomass did not vary with mean community wood density. The relationship between subcommunity biomass and mean wood density within a forest varied from negative to null to positive depending on the size of subcommunities and forest identity. The direction of correlation was determined by the associated total basal area,mean wood density correlation, the slope of which increased strongly with whole forest mean wood density. Main conclusions, There is no general relationship between forest biomass and wood density, and in some forests, stored carbon is highest where wood density is lowest. Our results suggest that declining wood density, due to global change, will result in decreased or increased stored carbon in forests with high or low mean wood density, respectively. [source]

Methods for evaluating human impact on soil microorganisms based on their activity, biomass, and diversity in agricultural soils

Rainer Georg Joergensen
Abstract The present review is focused on microbiological methods used in agricultural soils accustomed to human disturbance. Recent developments in soil biology are analyzed with the aim of highlighting gaps in knowledge, unsolved research questions, and controversial results. Activity rates (basal respiration, N mineralization) and biomass are used as overall indices for assessing microbial functions in soil and can be supplemented by biomass ratios (C : N, C : P, and C : S) and eco-physiological ratios (soil organic C : microbial-biomass C, qCO2, qNmin). The community structure can be characterized by functional groups of the soil microbial biomass such as fungi and bacteria, Gram-negative and Gram-positive bacteria, or by biotic diversity. Methodological aspects of soil microbial indices are assessed, such as sampling, pretreatment of samples, and conversion factors of data into biomass values. Microbial-biomass C (g (g soil),1) can be estimated by multiplying total PLFA (nmol (g soil),1) by the FPLFA -factor of 5.8 and DNA (g (g soil),1) by the FDNA -factor of 6.0. In addition, the turnover of the soil microbial biomass is appreciated as a key process for maintaining nutrient cycles in soil. Examples are briefly presented that show the direction of human impact on soil microorganisms by the methods evaluated. These examples are taken from research on organic farming, reduced tillage, de-intensification of land-use management, degradation of peatland, slurry application, salinization, heavy-metal contamination, lignite deposition, pesticide application, antibiotics, TNT, and genetically modified plants. [source]

Fish assemblages and rapid colonization after enlargement of an artificial reef off the Algarve coast (Southern Portugal)

MARINE ECOLOGY, Issue 4 2008
Francisco Leito
Abstract Artificial reefs (ARs) have been deployed in Algarve (Southern Portugal) coastal waters to contribute to the sustainability of local nearshore fisheries. Herein, we describe the colonization process of the recently deployed Faro/Anco AR, and assess the time until the fish assemblage reaches stability and their seasonal patterns. In addition, we compare the results from the present study with those previously reported for an older AR. The fish assemblages were monitored monthly over a 2-year period by means of visual census. A rapid increase in fish colonization occurred within the first 4 months. After this initial period the assemblage structure showed high similarity (> 73%). The high rate of colonization of the AR was related to the maturity already achieved by the nearby 14-year-old AR and to the fish migration from the Ria Formosa lagoon, a nearby nursery habitat. The reef fish assemblage structure showed a seasonal pattern, mainly associated with recruitment episodes of occasional demersal species (Boops boops, Trachurus trachurus and Pagellus spp.) in spring and summer. A total of 66% of the species found in AR are of commercial and recreational importance. The overall mean density and biomass were 2.8 indm,3 and 207 gm,3. The occasional demersal species accounted for 42% of the fish density. The most important species in terms of biomass belong to the Sparidae family along with Dicentrarchus labrax. The fish assemblage of the new ARs showed higher mean number of species, diversity, density and biomass values than those reported for the older AR. This result was associated with enlargement of the AR area and with the fishing exploitation of the isolated, small and patchy old AR. Moreover, the high biomass values recorded in the new ARs were mainly due to the increased density of D. labrax after AR enlargement. The results of the present study are used to define guidelines for suitable management strategies for the AR areas that are exploited by the local commercial and recreational fisheries. [source]

Allometry and biomass distribution in replanted mangrove plantations at Gazi Bay, Kenya

J. G. Kairo
Abstract 1.This study reports above-ground biomass of 5 and 8 years old mangrove plantations in Kenya. Trees with stem diameter greater than 5.0,cm inside 100,m2 sample plots were harvested, and then separated into stems (trunks), branches, leaves and prop roots. 2.Mean above-ground biomass was calculated at 20.25 t dry matter ha,1 for Rhizophora mucronata Lam., 11.7 t dry matter ha,1 for Avicennia marina (Forsk.) Vierh., 6.7 t dry matter ha,1 for Sonneratia alba Sm. and 3.7 t dry matter ha,1 for Ceriops tagal (Perr.) C. B. Robinson. In A. marina and R. mucronata, stems (52.19%) and prop-roots (30.28%), respectively, accounted for the highest proportion of the above-ground dry weight. While in S. alba and C. tagal, branch biomass represented the highest percentage of biomass, 48.20% and 43.62%, respectively. 3.The total above-ground biomass of R. mucronata was best estimated from regression equations using a combination of height and diameter above stilt root as the independent variables. For A. marina, C. tagal and S. alba there was no simple correlation found between the above-ground biomass and tree height or stem diameter. 4.Comparison of the regression models with those developed elsewhere gave different biomass values in these plots, further reinforcing the need for the use of site-specific allometric equations for biomass estimation. Copyright 2009 John Wiley & Sons, Ltd. [source]