Impact of ocean acidification on a key Arctic pelagic mollusc (Limacina helicina)

Thecosome pteropods (shelled pelagic molluscs) can play an important role in the food web of various ecosystems and play a key role in the cycling of carbon and carbonate. Since they harbor an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The impact of changes in the carbonate chemistry was investigated on Limacina helicina, a key species of Arctic ecosystems. Pteropods were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems

Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions

Dissection of the Complex Phenotype in Cuticular Mutants of Arabidopsis Reveals a Role of SERRATE as a Mediator

Mutations in LACERATA (LCR), FIDDLEHEAD (FDH), and BODYGUARD (BDG) cause a complex developmental syndrome that is consistent with an important role for these Arabidopsis genes in cuticle biogenesis. The genesis of their pleiotropic phenotypes is, however, poorly understood. We provide evidence that neither distorted depositions of cutin, nor deficiencies in the chemical composition of cuticular lipids, account for these features, instead suggesting that the mutants alleviate the functional disorder of the cuticle by reinforcing their defenses. To better understand how plants adapt to these mutations, we performed a genome-wide gene expression analysis. We found that apparent compensatory transcriptional responses in these mutants involve the induction of wax, cutin, cell wall, and defense genes. To gain greater insight into the mechanism by which cuticular mutations trigger this response in the plants, we performed an overlap meta-analysis, which is termed MASTA (MicroArray overlap Search Tool and Analysis), of differentially expressed genes. This suggested that different cell integrity pathways are recruited in cesA cellulose synthase and cuticular mutants. Using MASTA for an in silico suppressor/enhancer screen, we identified SERRATE (SE), which encodes a protein of RNA–processing multi-protein complexes, as a likely enhancer. In confirmation of this notion, the se lcr and se bdg double mutants eradicate severe leaf deformations as well as the organ fusions that are typical of lcr and bdg and other cuticular mutants. Also, lcr does not confer resistance to Botrytis cinerea in a se mutant background. We propose that there is a role for SERRATE-mediated RNA signaling in the cuticle integrity pathway

Warfarin related intracranial haemorrhage : a case-controlled study of anticoagulation monitoring prior to spontaneous subdural or intracerebral haemorrhage

We present a retrospective, case-controlled study of the degree of over-warfarinisation and the frequency of International Normalized Ratio (INR) monitoring in patients with spontaneous intracranial haemorrhage (ICH) compared with a control group without ICH. A higher proportion of patients with ICH were taking warfarin than patients in the control group (33/221 [15%] versus 16/201 [8%], p < 0.05). There was no significant difference between the ICH group and the controls in the mean INR of warfarinised patients on presentation, the mean INR when last measured prior to presentation, or in the number of days since the INR was last tested. There was no correlation between the time since the INR was last measured and the INR on presentation. Only 2 (6%) of patients were excessively anticoagulated at the time of ICH. Thus, in this study, warfarin use was associated with an increased risk of ICH despite appropriate community INR monitoring and therapeutic anticoagulation.4 page(s

Warfarin related intracranial haemorrhage: a case-controlled study of anticoagulation monitoring prior to spontaneous subdural or intracerebral haemorrhage

We present a retrospective, case-controlled study of the degree of over-warfarinisation and the frequency of International Normalized Ratio (INR) monitoring in patients with spontaneous intracranial haemorrhage (ICH) compared with a control group without ICH. A higher proportion of patients with ICH were taking warfarin than patients in the control group (33/221 [15%] versus 16/201 [8%], p < 0.05). There was no significant difference between the ICH group and the controls in the mean INR of warfarinised patients on presentation, the mean INR when last measured prior to presentation, or in the number of days since the INR was last tested. There was no correlation between the time since the INR was last measured and the INR on presentation. Only 2 (6%) of patients were excessively anticoagulated at the time of ICH. Thus, in this study, warfarin use was associated with an increased risk of ICH despite appropriate community INR monitoring and therapeutic anticoagulation