Fundamental Connections Among Organism C:n:p Stoichiometry, Macromolecular Composition, and Growth

Abstract

Whereas it is acknowledged that the C:N:P stoichiometry of consumers and their resources affects both the structure and the function of food webs, and eventually influences broad‐scale processes such as global carbon cycles, the mechanistic basis for the variation in stoichiometry has not yet been fully explored. Empirical evidence shows that the specific growth rate is positively related to RNA concentration both between and within taxa in both unicellular and multicellular organisms. Since RNA is rich in P and constitutes a substantial part of the total P in organisms, a high growth rate is also connected with a high P content. We argue that the reason for this pattern is that the growth of all biota is closely linked with their protein synthesis rate, and thus with the concentration of ribosomal RNA. Dynamic energy budget theory supports the positive relationship between RNA and specific growth rate in microorganisms, whereas the predictions concerning multicellulars only partially agrees with the observed pattern. In a simple model of consumer growth, we explore the consequences of various allocation patterns of RNA, protein, carbohydrates/lipids, and other biochemical constituents on organism potential growth rate and C:N:P stoichiometry. According to the model the percentage of N and especially percentage of P per dry mass increases with increasing specific growth rate. Furthermore, the model suggests that macromolecule allocation patterns and thus N:P stoichiometry are allowed to differ substantially at low growth rates whereas the stoichiometry at high growth rates is much more constricted at low N:P. The model fits empirical data reasonably well, but it is also acknowledged that complex life cycles and associated physiological constraints may result in other patterns. We also use a similar approach of modeling organism growth from basic biochemical principles to illustrate fundamental connections among biochemical allocation and C:N stoichiometry in autotroph production, which is based on allocation patterns between carbohydrates and rubisco. Similar to the RNA–protein model, macromolecular composition and C:N ratios are more constrained at high than at low growth rates. The models and the empirical data together suggest that organism growth is tightly linked with the organisms' biochemical and elemental composition. The stoichiometry of growth impinges on nutrient cycles and carbon fluxes at the ecosystem level. Thus, focus on the biological basis of organism C:N:P stoichiometry can mechanistically connect growth strategy and biochemical and cellular mechanisms of biota to major ecological consequences.

Effect of Input Production against Quality of Cocoa Beans

“…This research is relevant to the research of Sokri et al (2013), where nitrate had effects on fruit ripening. This makes sense, as Nitrogen (N) is the primary nutrient for crops and important for all organisms (Vrede et al, 2004).…”

“…It showed the usage of SP-36 fertilizers on cocoa crops could cause cocoa beans to grow larger and far more solid so that total beans reduced per 100 g of dry cocoa beans. Phosphorus (P), the primary nutrient for crops and important for all organisms (Vrede et al, 2004), is an important element in the production of ribosomes (Agren, 2008). Protein synthesis requires P in promoting growth (Elser et al, 2000;Hessen et al, 2007).…”

Coupling of growth rate and body stoichiometry in Daphnia: a role for maintenance processes?

“…Thus, differences in overall protein synthesis demands (and thus RNA levels) may be set not only by growth-related demands but also by potential differences among species in the relative importance and pathways of protein retention and reclamation in overall metabolism. To our knowledge, no empirical studies of protein turnover have yet been performed for Daphnia, despite the importance of assumptions about protein turnover for emerging stoichiometric models of Daphnia growth and metabolism (Vrede et al, 2004;Anderson et al, 2005). Life histories vary widely among taxa.…”

Sex and size matter: ontogenetic patterns of nutrient content of aquatic insects

“…Unlike deoxyribonucleic acid (DNA), quantities of ribosomes, mRNA, and rRNA are not fixed in cells, and changes in these constituents can alter the amount of cellular P (Sterner and Elser 2002). Transcription rates and protein synthesis are positively correlated with P supply (Acharya et al 2004, Vrede et al 2004, Weider et al 2005. Nutrient ratios also are important because growth requires different relative amounts of C, N, and P, and other elements (Elser et al 1996, Sterner and.…”