Differential Nutrient Uptake by Saltmarsh Plants Is Modified by Increasing Salinity.

In Southern European estuaries and associated salt marshes, the anthropogenic nutrient inputs, together with longer drought periods, are leading to increasing eutrophication and salinization of these coastal ecosystems. In this study, uptake kinetics of ammonium, nitrate, and phosphate by three common plants in Palmones salt marsh (Southern Spain), Sarcocornia perennis ssp. alpini, Atriplex portulacoides, and Arthrocnemum macrostachyum were measured in hydroponic cultures. We also determined how these uptakes could be modified by increasing salinity, adding NaCl to the incubation medium (from 170 to 1,025 mM). Kinetic parameters are analyzed to understand the competition of the three species for nutrient resources under realistic most frequent concentrations in the salt marsh. These results may also be useful to predict the possible changes in the community composition and distribution if trends in environmental changes persist. Atriplex portulacoides showed the highest Vmax for ammonium, the most abundant nutrient in the salt marsh, while the highest affinity for this nutrient was observed in A. macrostachyum. Maximum uptake rates for nitrate were much lower than for ammonium, without significant differences among species. The highest Vmax value for phosphate was observed in A. macrostachyum, whereas A. portulacoides presented the highest affinity for this nutrient. High salinity drastically affected the physiological response of these species, decreasing nutrient uptake. Sarcocornia perennis ssp. alpini and A. macrostachyum were not affected by salinity up to 510 mM NaCl, whereas A. portulacoides notably decreased its uptake capacity at 427 mM and even withered at 1,025 mM NaCl. At current most frequent concentrations of ammonium and phosphate in the salt marsh, S. perennis ssp. alpini is the most favored species, from the nutritional point of view. However, A. portulacoides could enhance its presence if the increasing ammonium load continues, although a simultaneous salinization would negatively affect its nutritional physiology.

Assessing global range expansion in a cryptic species complex: insights from the red seaweed genus Asparagopsis (Florideophyceae).

The mitochondrial genetic diversity, distribution and invasive potential of multiple cryptic operational taxonomic units (OTUs) of the red invasive seaweed Asparagopsis were assessed by studying introduced Mediterranean and Hawaiian populations. Invasive behavior of each Asparagopsis OTU was inferred from phylogeographic reconstructions, past historical demographic dynamics, recent range expansion assessments and future distributional predictions obtained from demographic models. Genealogical networks resolved Asparagopsis gametophytes and tetrasporophytes into four A. taxiformis and one A. armata cryptic OTUs. Falkenbergia isolates of A. taxiformis L3 were recovered for the first time in the western Mediterranean Sea and represent a new introduction for this area. Neutrality statistics supported past range expansion for A. taxiformis L1 and L2 in Hawaii. On the other hand, extreme geographic expansion and an increase in effective population size were found only for A. taxiformis L2 in the western Mediterranean Sea. Distribution models predicted shifts of the climatically suitable areas and population expansion for A. armata L1 and A. taxiformis L1 and L2. Our integrated study confirms a high invasive risk for A. taxiformis L1 and L2 in temperate and tropical areas. Despite the differences in predictions among modelling approaches, a number of regions were identified as zones with high invasion risk for A. taxiformis L2. Since range shifts are likely climate-driven phenomena, future invasive behavior cannot be excluded for the rest of the lineages.

Mechanisms of inorganic carbon acquisition in two estuarine Rhodophyceans: Bostrychia scorpioides (Hudson) ex Kützing Montagne and Catenella caespitosa (Withering) L. M. Irvine.

Marine macroalgae possess a range of mechanisms to increase the availability of CO2 for fixation by ribulose-1,5-bisphosphate carboxylase/oxygenase. Of these, possession of a periplasmic or external carbonic anhydrase and the ability to use bicarbonate ions is widely distributed. The mechanisms of carbon acquisition were studied in two estuarine red macroalgae Bostrychia scorpioides and Catenella caespitosa using a range of techniques. pH-drift and CO2-depletion experiments at constant pH suggested that CO2 is the main source of inorganic carbon in both species. Inhibitors indicated that internal and external carbonic anhydrase were present in both species. Inhibitors also suggested that uptake of bicarbonate is unlikely to be present (P < 0.05).

Human chorionic gonadotropin and vascular endothelial growth factor in normal and complicated pregnancies.

OBJECTIVE: To study the relationships between maternal serum concentrations of beta-human chorionic gonadotropin (hCG) and vascular endothelial growth factor (VEGF) in both normal pregnant women during late pregnancy and women with pregnancy complications. METHODS: Sixty-six women in three groups were prospectively studied: 1) women diagnosed with fetal growth restriction (n = 22), 2) women with preeclampsia (n = 22), and 3) healthy pregnant women (controls) frequency matched for age, parity, and gestational age (n = 22). Primary outcomes were maternal serum concentrations of both beta-hCG and VEGF. Placental insufficiency was defined by a pulsatility index in umbilical artery greater than the 99th percentile for gestation. RESULTS: Maternal serum concentrations of beta-hCG and VEGF were greater in women with preeclampsia than in controls (P = .001 and P = .002, respectively) and women with fetal growth restriction (P = .002 and P = .002, respectively). Concentrations did not differ between women with fetal growth restricted fetuses and controls. Correlation between beta-hCG and VEGF was not significant in any of the studied groups. Serum VEGF concentrations were significantly increased in a subgroup of 12 women with placental insufficiency (P = .04) and correlated with beta-hCG concentrations (r = .63, P = .02). CONCLUSION: Both VEGF and beta-hCG maternal serum concentrations were increased in women with preeclampsia but normal in women with fetal growth restriction, although VEGF concentrations were increased in those cases with placental insufficiency. Maternal serum beta-hCG and VEGF concentrations did not correlate except in women with placental insufficiency.

Inflammatory cytokines in intrauterine growth retardation.

BACKGROUND: To evaluate maternal serum levels of two inflammatory cytokines in women with intrauterine growth retardation (IUGR), while studying separately women with or without placental insufficiency. METHODS: The study comprised 14 women with IUGR and Doppler-defined placental insufficiency, 14 women with IUGR without placental insufficiency, and 28 healthy pregnant women as a control group. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured using a commercially available kit. The Kruskal-Wallis test and the corrected Mann-Whitney U-test were used. RESULTS: There was a statistically significant difference in TNF-alpha levels among the three studied groups (p = 0.03). Women with IUGR and placental insufficiency showed statistically significant higher serum levels of TNF-alpha[2.2 pg/mL (1.3-4.1)] and a higher rate of detectable TNF-alpha[85.7% (12/14)] than those in the control group [0 pg/mL (0-2.7) and 32.1% (9/28)] (p = 0.01 and p = 0.001, respectively). On the contrary, there was no difference in either the TNF-alpha level [1.4 pg/mL (0-4.9)] or the rate of detectable TNF-alpha[57.1% (8/14)] between women with IUGR without placental insufficiency and women in the control group. The levels of IL-6 were similar in the three studied groups. CONCLUSION: TNF-alpha is increased in women with IUGR and placental insufficiency but normal in those with IUGR and normal placental perfusion. We suggest that elevations of TNF-alpha could be a specific phenomenon of certain subsets of IUGR, identifying cases with placental dysfunction.

Insulin, insulin-like growth factor-1, and insulin resistance in women with pregnancy-induced hypertension.

OBJECTIVE: The purpose of this study was to assess insulin, insulin sensitivity, and insulin-like growth factor-I in women with preeclampsia and gestational hypertension. STUDY DESIGN: Insulin resistance was measured with the short insulin-tolerance test in 20 women with preeclampsia, in 18 women with gestational hypertension, and in 20 normotensive control subjects. Sex hormone binding globulin, insulin-like growth factor-I, glucose, fructosamine, glycosylated hemoglobin, insulin, C-peptide, and lipids were measured in the fasting state. RESULTS: Women with gestational hypertension had a significant lower insulin sensitivity index (0.13 +/- 0.1) and a higher level of insulin-like growth factor-I (333.71 +/- 107.6 ng/mL) than women in the control group (0.21 +/- 0.1 [P <.05]; 218.11 +/- 82.3 ng/mL [P <.01]) and women with preeclampsia (0.21 +/- 0.12 [P <.05]; 234.78 +/- 92.76 ng/mL [P <.01]). There were no significant correlations between insulin sensitivity index and insulin-like growth factor-I. CONCLUSION: Insulin resistance is present in women with gestational hypertension but not in women with preeclampsia and did not correlate with insulin-like growth factor-I.

Limited acclimation of photosynthesis to blue light in the seaweed Gracilaria tenuistipitata.

Changes in photosynthetic capacity of the seaweed Gracilaria tenuistipitata Zhang et Xia acclimated to monochromatic blue light were studied. For this purpose, affinity for external inorganic carbon, light use efficiency, carbonic anhydrase (CA; EC 4.2.1.1) activity and content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) were determined in thalli acclimated to 45 &mgr;mol m-2 s-1 of blue light. Thalli cultured in white light of the same photon fluence rate were used as a control. Lower maximal photosynthetic rates (i.e. at light and carbon saturation) were obtained in the thalli cultured in blue light. Apparently, this lower photosynthetic capacity was not due to differences in affinity and/or capacity for use of external dissolved inorganic carbon (DIC) since (1) CA activity did not change significantly and (2) similar values of photosynthetic conductance for DIC at alkaline pH were obtained (0.95 x 10-6 m s-1). In addition, the pool size of Rubisco was not modified by the blue light treatment since there were no significant differences in Rubisco content between white (12.14% of soluble proteins) and blue light (12.13% of soluble proteins) treatments. In contrast, Fv/Fm was increased by 11% and photosynthetic efficiency for oxygen production was reduced by 50% in blue light. This absence of correlation between quantum yields for maximum stable charge separation of photosystem II and oxygen evolution suggests that blue light promote changes in rates of photosynthetic electron flow.