Global mangrove root production,its controls and roles in the blue carbon budget of mangroves

Mangroves are among the most carbon-dense ecosystems worldwide. Most of the carbon in mangroves is found belowground, and root production might be an important control of carbon accumulation, but has been rarely quantified and understood at the global scale. Here, we determined the global mangrove root production rate and its controls using a systematic review and a recently formalised, spatially explicit mangrove typology framework based on geomorphological settings. We found that global mangrove root production averaged ~770 ± 202 g of dry biomass m⁻² year⁻¹ globally, which is much higher than previously reported and close to the root production of the most productive tropical forests. Geomorphological settings exerted marked control over root production together with air temperature and precipitation (r² ≈ 30%, p < .001). Our review shows that individual global changes (e.g. warming, eutrophication, drought) have antagonist effects on root production, but they have rarely been studied in combination. Based on this newly established root production rate, root-derived carbon might account for most of the total carbon buried in mangroves, and 19 Tg C lost in mangroves each year (e.g. as CO₂). Inclusion of root production measurements in understudied geomorphological settings (i.e. deltas), regions (Indonesia, South America and Africa) and soil depth (>40 cm), as well as the creation of a mangrove root trait database will push forward our understanding of the global mangrove carbon cycle for now and the future. Overall, this review presents a comprehensive analysis of root production in mangroves, and highlights the central role of root production in the global mangrove carbon budget.     

Environmental conditions during glycerol bioconversion affect 3-hydroxypropionic acid bioproduction by Limosilactobacillus reuteri DSM 17938

3-Hydroxypropionic acid (3-HP) is a platform molecule whose biological production was carried out by the bacterium Limosilactobacillus reuteri according to a two-step process: first, a growth phase in batch mode on glucose, then a glycerol bioconversion into 3-HP in fed-batch mode. With the objective of improving 3-HP bioproduction, this study aimed at defining the operating conditions during the bioconversion phase that increases the bioproduction performance. A central composite rotatable design allowed testing various pH levels and specific glycerol feeding rates. By establishing response surfaces, optimal conditions have been identified that were different depending on the considered output variable (final 3-HP quantity, 3-HP production yield and production rate). Of them, 3-HP final quantity and 3-HP production yield were maximized at pH 6.0 and at specific glycerol feeding rates of 60 and 55 mg_gly g_CDW⁻¹ h⁻¹, respectively. The specific 3-HP production rate was the highest at the upper limit of the specific substrate feeding rate (80 mg_gly g_CDW⁻¹ h⁻¹) but was not affected by the pH. An additional experiment was carried out at pH 6.0 and a specific glycerol feeding rate of 80 mg_gly g_CDW⁻¹ h⁻¹ to validate the previous observations. In conclusion, the results showed a significant improvement of 3-HP concentration by 13%, of specific production rate by 34% and of 3-HP volumetric productivity by 39%, as compared to the initial values.     

EFFECTS OF ENVIRONMENTAL VARIATION ON SINKING RATES OF MARINE PHYTOPLANKTON1

The effects of environmental variables, particularly irradiance, on the sinking rates of phytoplankton were investigated using cultures of Chaetoceros gracilis Schütt and C. flexuosum Mangin in laboratory experiments; these data were compared with results from assemblages in the open ocean and marginal ice zone of the Greenland Sea. In culture experiments both the irradiance under which the diatom was grown and culture growth rate were positively correlated with sinking rates. Sinking rates (ψ) in the Greenland Sea were smallest when determined from chlorophyll (mean ψ_chl= 0.14 m · d^?1) and biogenic silica (ψ_si= 0.14 m · d^?1) and greatest when determined from particulate carbon (ψ_c= 0.55 m · d^?1) and nitrogen (ψ_N= 0.64 m · d^?1). Field measurements indicated that variations in sinking may be associated with changes in irradiance and nitrate concentrations. Because these factors do not directly affect water density, they must be inducing physiological changes in the cell which affect buoyancy. Although a direct response to a single environmental variable was not always evident, sinking rates were positively correlated with growth rates in the marginal ice zone, further indicating a connection to physiological processes. Estimats of carbon flux at stations with vertically mixed euphotic zones indicated that approximately 30% of the daily primary production sank from the euphotic zone in the form of small particulates. Calculated carbon flux tended to increase with primary productivity.     

Comparison of carbohydrate utilization and energy charge in the yellow flag iris (Iris pseudacorus) and garden iris (Iris germanica) under anoxia

Carbohydrate and energy metabolism of the flooding- and anoxia-tolerant Iris pseudacorus and the intolerant Iris germanica rhizomes were investigated under experimental anoxic conditions. Rhizomes of I. pseudacorus and I. Germanica were incubated in the absence of oxygen from 0 to 60 and 16 days, respectively. Amounts of glucose, total reducing sugars and non-reducing sugars (starch, fructan and oligosaccharides) in the rhizomes were measured. Ethanol concentration and adenylate energy charge were determined enzymatically. Glucose content of I. pseudacorus rhizomes decreased gradually during the first 30 days under anoxia and then increased at the same time as adenylate energy charge values started to decline. In I. germanica rhizomes the changes were more dramatic and the time scale was much shorter than in I. pseudacorus but the changes were similar. Non-reducing sugar content of I. pseudacorus rhizomes decreased rapidly during the first 15 days under oxygen deprivation and then increased again, to near starting levels at 35 days. In I. germanica the amount of non-reducing sugars decreased gradually during the anoxic incubation. Under aerobic control conditions, adenylate energy charge (AEC) of I. pseudacorus and I. germanica rhizome tissue was 0.87±0.01 and 0.81±0.01, respectively. In I. pseudacorus AEC remained high until 30 days under anoxia. In contrast, the energy charge of I. germanica rhizome tissue remained above 0.6 for 4 days only. Large amounts of ethanol were found in anoxic rhizome tissues of I. pseudacorus (up to 0.21 M ) and I. germanica (0.06 M ) after 45 days and 8 days, respectively. The results are discussed in relation to flooding tolerance of these species.     

Towards an understanding of the relations between tree nutrition,nutrient cycling and environment

The paper contains a discussion of the interrelations between the sciences used by managers of forest land to improve their management, in particular with respect to the plant nutrient economy of the forest ecosystems. Both site studies and studies of nutrient cycling have been carried out for long periods without proper consideration of tree nutrition. Therefore these studies contributed less to the understanding of the role of nutrients as regulators of processes in ecosystems than might have been expected. This situation has improved, especially within the last decade. In addition the necessity to manage forest land for environmental values as well as for forest yield requires new interdisciplinary approaches in the study of the roles of plant nutrients in the forest. Even more branches of biological and environmental sciences than those just mentioned must be involved.     

Phytoplankton primary production in a mesotrophic pond in sub-tropical Bangladesh

Annual gross primary productivity in mesotrophic Shahidullah Hall pond (Dhaka, Bangladesh) was 1383.35 g C m⁻² y⁻¹ (arithmetic mean). Daily primary productivity (between 1.6 and 6.8 g C m⁻² d⁻¹ was correlated with chlorophylla, day length and dissolved silica. Chlorophylla related significantly withk, incident light, SRP, alkalinity and conductivity. A negative correlation existed between biomass and rainfall. Productivity, biomass, conductivity, alkalinity, and SRP increased after mid-winter.k, I _k andZ _eu varied according seasonally.P _max related directly with temperature. Seasonal variation of ∝ ^B was 0.0049–0.0258 mg C (mg chla mmol PAR)⁻¹ m⁻². Q₁₀ was 2.12, community respiration 1334.99 g C m⁻² y⁻¹, and the underwater light climate 186.43μE m⁻² s⁻¹.     

The role of glucose in ajmalicine production by catharanthus roseus cell cultures

The role of glucose in ajmalicine production by Catharanthus roseus was investigated in the second stage of a two-stage batch process. Activities of tryptophan decar-boxylate (TDC) and anthranilate synthase (AS), two enzymes In the pathway leading to ajmalicine, were higher after induction with 40 g/L glucose than after induction with 60 or 80 g/L glucose. Experiments with different media containing mixtures of glucose and the nonpermeating osmotic agent xylose, and using an already induced culture as inoculum, revealed that a minimum amount of glucose is required to support ajmalicine production after enzyme induction. This requirement was not an osmotic effect. The relation between the glucose concentration and the specific ajmalicine production rate, q(p), was investigated in seven (fed-)batch cultures with constant glucose concentrations: 23, 29, 35, 53, 57, 75, and 98 g/L. In the cultures with a low glucose concentration (23, 29, and 35 g/L) the q(p) was 2.7-times higher than the cultures with 53 and 57 g/L, and almost six times higher than the cultures with a high glucose concentration (75 and 98 g/L). A glucose perturbation experiment (from 53 to 32 g/L) demonstrated that the ajmalicine production rate was adjusted without much delay. A kinetic equation is proposed for the relationship between the glucose concentration and q(p). Differences in enzyme induction and ajmalicine production at different glucose levels could not be explained by the intracellular concentrations of glucose, fructose, sucrose, or starch. (c) 1995 John Wiley & Sons Inc.     

Fermenter production of an artificial fab fragment,rationally designed for the antigen cystatin,and its optimized crystallization through constant domain shuffling

The synthetic antibody model “M41” was rationally designed with a binding site complementary to chicken egg white cystatin as the prescribed antigen. In order to permit comparison between the computer model and an experimental three-dimensional structure of the artificial protein, its X-ray crystallographic analysis was pursued. For this purpose, M41 was expressed as a recombinant Fab fragment in E. coli by medium cell density fermentation employing the tightly regulated tetracycline promoter. The Fab fragment was efficiently purified via a His-6 tail fused to its heavy chain and immobilized metal affinity chromatography. To raise the chances for the productive formation of crystal packing contacts, three versions of the Fab fragment were generated with differing constant domains. One of these, the variant with murine C_K and C_H 1_γ1 domains, was successfully crystallized by microseeding in a sitting drop. The orthorhombic crystals exhibited symmetry of the space group P2₁2₁2₁ with unit cell dimensions a = 104.7 Å, b = 113.9 Å, c = 98.8 Å and diffracted X-rays to a nominal resolution of 2.5 Å. © 1995 Wiley-Liss, Inc.     

Stabile production of a thrombin resistant pro-urokinase derivative (PRO-UKS1) by Namalwa KJM-1 cells adapted to serum-free medium

Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml^–1. Addition of glucose and tri-iodothyronine (T₃) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml^–1 day^–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA bovine serum albumin - dhfr dihydrofolate reductase - HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - kb kilobase pairs - kDa kilodaltons - MTX Methotrexate - PBS phosphate buffered saline - pro-UK pro-urokinase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - T₃ tri-iodothyronine - Tween-PBS phosphate buffered saline containing 0.05% Tween 80