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Termination of antidepressant therapy often has negative consequences. Although symptoms of antidepressant withdrawal are widely recognized, the molecular processes that underlie them are not well characterized. We show that certain aspects of Gαs signaling remain suppressed after antidepressant withdrawal, even after others have reverted to baseline. Antidepressant treatment causes translocation of Gαs protein from lipid rafts to nonraft membrane regions. This results in augmented Gαs signaling, including facilitated activation of adenylyl cyclase and increased cAMP accumulation. Using CC6 or SK-N-SH cells and a lipid raft–localized cAMP sensor, we show that Gαs signaling is reduced in lipid rafts, even while signaling is enhanced elsewhere in the cell. These signaling changes mirror the changes in Gαs localization observed after antidepressant treatment. Furthermore, we show that suppression of Gαs signaling in lipid rafts persists at least 24 hours after cessation of antidepressant treatment. Gαs localization was quantified after membrane isolation and sequential detergent extraction. We show that suppression of lipid raft Gαs signaling persists for an extended time period after antidepressant withdrawal, whereas increased nonraft membrane Gαs signaling reverts partially or fully upon cessation of antidepressant treatment. Translocation of Gαs out of lipid rafts is also persistent. These events may reflect cellular adaptations to antidepressant treatment that contribute to antidepressant discontinuation syndromes and may aid in the discovery of new treatments and strategies to mitigate the symptoms of depression and antidepressant withdrawal. SIGNIFICANCE STATEMENT This work explores, for the first time, the effects of antidepressants on Gαs signaling after drug withdrawal. This provides novel insight into the cellular and molecular processes affected by antidepressant drugs and their persistence after discontinuation of treatment.

To investigate the role of mechanical constraints in morphogenesis and development, we develop a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane (PDMS) mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate submitted to uniaxial compression. The local shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the Zebrafish embryo during gastrulation, our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue, and its time evolution.

Branched actin networks polymerized by the Arp2/3 complex are critical for cell migration. The WAVE complex is the machinery that activates Arp2/3 in a RAC1-dependent manner at the leading edge of migrating cells. Multiple WAVE complexes are assembled in a cell through various combinations of paralogous subunits. Here we report the surprising phenotype associated with loss-of-function of CYFIP2, a subunit of the WAVE complex. In three different human mammary cell lines and in prechordal plate cells of gastrulating zebrafish embryos, CYFIP2 depletion promoted, rather than impaired, membrane protrusions and migration persistence. CYFIP2, however, assembled WAVE complexes that polymerize branched actin at the cell cortex and rescued membrane protrusions of CYFIP1/2 double knock-out cells, although less efficiently than CYFIP1. Point mutations of CYFIP2 associated with intellectual disability in children were gain-of-function, as they made CYFIP2 as active as CYFIP1 in this rescue experiment. Biochemical reconstitutions of CYFIP2-containing WAVE complexes showed that they bound equally well to active RAC1 as CYFIP1-containing WAVE complexes, yet they were poorly activated in response to RAC1 binding. Together these results suggest that CYFIP2-containing WAVE complexes titrate active RAC1 and thereby prevent efficient CYFIP1-containing complexes from being activated. In this context, where cell migration is governed by the balance of CYFIP1/2 expression, releasing the restrained activity of CYFIP2-containing WAVE complexes leads to pathology.

Water cycling between Earth's mantle and surface has previously been modelled and extrapolated to rocky exoplanets, but these studies neglected the host star. M-dwarf stars are more common than Sun-like stars and at least as likely to host temperate rocky planets (M-Earths). However, M dwarfs are active throughout their lifetimes; specifically, X-ray and extreme ultraviolet (XUV) radiation during their early evolution can cause rapid atmospheric loss on orbiting planets. The increasing bolometric flux reaching M-Earths leads to warmer, moister upper atmospheres, while XUV radiation can photodissociate water molecules and drive hydrogen and oxygen escape to space. Here, we present a coupled model of deep-water cycling and water loss to space on M-Earths to explore whether these planets can remain habitable despite their volatile evolution. We use a cycling parameterization accounting for the dependence of mantle degassing on seafloor pressure, the dependence of regassing on mantle temperature, and the effect of water on mantle viscosity and thermal evolution. We assume the M dwarf's XUV radiation decreases exponentially with time, and energy-limited water loss with 30% efficiency. We explore the effects of cycling and loss to space on planetary water inventories and water partitioning. Planet surfaces desiccated by loss can be rehydrated, provided there is sufficient water sequestered in the mantle to degas once loss rates diminish at later times. For a given water loss rate, the key parameter is the mantle overturn timescale at early times: if the mantle overturn timescale is longer than the loss timescale, then the planet is likely to keep some of its water., Comment: 10 pages, 4 figures, accepted for publication in MNRAS

Opioid drugs are the gold standard for the management of pain, but their use is severely limited by dangerous and unpleasant side effects. All clinically available opioid analgesics bind to and activate the mu-opioid receptor (MOR), a heterotrimeric G-protein-coupled receptor, to produce analgesia. The activity of these receptors is modulated by a family of intracellular RGS proteins or regulators of G-protein signaling proteins, characterized by the presence of a conserved RGS Homology (RH) domain. These proteins act as negative regulators of G-protein signaling by serving as GTPase accelerating proteins or GAPS to switch off signaling by both the Gα and βγ subunits of heterotrimeric G-proteins. Consequently, knockdown or knockout of RGS protein activity enhances signaling downstream of MOR. In this review we discuss current knowledge of how this activity, across the different families of RGS proteins, modulates MOR activity, as well as activity of other members of the opioid receptor family, and so pain and analgesia in animal models, with particular emphasis on RGS4 and RGS9 families. We discuss inhibition of RGS proteins with small molecule inhibitors that bind to sensitive cysteine moieties in the RH domain and the potential for targeting this family of intracellular proteins as adjuncts to provide an opioid sparing effect or as standalone analgesics by promoting the activity of endogenous opioid peptides. Overall, we conclude that RGS proteins may be a novel drug target to provide analgesia with reduced opioid-like side effects, but that much basic work is needed to define the roles for specific RGS proteins, particularly in chronic pain, as well as a need to develop newer inhibitors.

A single base mutation in the Gα(i2) protein (G184S) renders this Gα subunit insensitive to the negative modulatory effects of Regulator of G-protein Signaling (RGS) proteins. Mice expressing this RGS insensitive (RGSi) variant of Gα(i2) (RGSi Gα(i2)) display a spontaneous antidepressant-like phenotype that is reversible by treatment with the 5-HT1A receptor (5-HT1AR) antagonist WAY100635. Here we test the hypothesis that increased activity of 5-HT1ARs in the hippocampus of RGSi Gα(i2) knock-in mice is responsible for the expression of the observed antidepressant-like behavior. We administered the 5-HT1AR antagonist WAY100635 or the agonist 8-OH-DPAT via bilateral intra-hippocampal infusion cannulae and evaluated antidepressant-like behavior using the tail suspension test (TST). WAY100635 reversed the antidepressant-like phenotype of the RGSi Gα(i2) knock-in mice and 8-OH-DPAT produced an antidepressant-like response in wild type mice that was blocked by systemic WAY100635. Furthermore, intra-hippocampal infusion of the RGS4/19 inhibitor CCG-203769 produced an antidepressant-like effect in female mice. Ex-vivo slice recording confirmed the 5-HT1AR-mediated decrease in hippocampal CA1 pyramidal neuron excitability was enhanced in the RGSi Gα(i2) knock-in mice. There was no change in hippocampal 5-HT1AR expression as measured by ligand binding or in the ability of 8-OH-DPAT to activate G-protein as measured in the [(35)S]GTPγS binding assay. The findings demonstrate that RGS protein control of hippocampal 5-HT1AR signaling is necessary and sufficient to account for the antidepressant-like phenotype in the RGSi Gα(i2) knock-in mice and that RGS proteins highly expressed in the hippocampus should be investigated as targets for novel antidepressant therapies.

Comparing microphysical models of aerosol production to Hubble Space Telescope transit spectra reveals a surprisingly simple transition between atmospheres with hydrocarbon hazes, silicate clouds and clear skies.

The work presented in this paper comprises an extensive testing program on the resistance of portland-limestone cement (PLC) concrete systems to external sulfate attack. Several mixture parameters, namely interground limestone content, C3A content, and SCM type and replacement level, were evaluated in a wide range of experimental conditions designed to link, replicate, and predict laboratory and field performances. The presented results have highlighted the role that the experimental parameters play in the degradation process, which were shown to be particularly pronounced in systems of low sulfate resistance with high limestone contents, owing to their high propensity for thaumasite formation. The findings presented will be crucial to evaluate/develop an accelerated testing procedure that provides a better correlation with actual field performance of concrete structures.

Ketamine produces rapid and robust antidepressant effects in depressed patients within hours of administration, often when traditional antidepressant compounds have failed to alleviate symptoms. We hypothesized that ketamine would translocate Gα(s) from lipid rafts to non-raft microdomains, similarly to other antidepressants but with a distinct, abbreviated treatment duration. C6 glioma cells were treated with 10 μM ketamine for 15 min, which translocated Gα(s) from lipid raft domains to non-raft domains. Other NMDA antagonist did not translocate Gα(s) from lipid raft to non-raft domains. The ketamine-induced Gα(s) plasma membrane redistribution allows increased functional coupling of Gα(s) and adenylyl cyclase to increase intracellular cyclic adenosine monophosphate (cAMP). Moreover, increased intracellular cAMP increased phosphorylation of cAMP response element-binding protein (CREB), which, in turn, increased BDNF expression. The ketamine-induced increase in intracellular cAMP persisted after knocking out the NMDA receptor indicating an NMDA receptor-independent effect. Furthermore, 10 μM of the ketamine metabolite (2R,6R)-hydroxynorketamine (HNK) also induced Gα(s) redistribution and increased cAMP. These results reveal a novel antidepressant mechanism mediated by acute ketamine treatment that may contribute to ketamine’s powerful antidepressant effect. They also suggest that the translocation of Gαs from lipid rafts is a reliable hallmark of antidepressant action that might be exploited for diagnosis or drug development.

CLA egg accumulation studies using cis, trans (c,t) isomers have been effective, but they reported adverse egg quality. trans, trans (t,t) CLA isomers have shown superior nutritional effects in rodent studies, but reports of t,t CLA-rich yolks are limited. The objectives were to determine the effect of t,t CLA-rich soy oil in feed on egg yolk viscosity, and yolk quality during refrigerated storage. Yolk fatty acids, viscosity, weight, index, moisture, pH, and vitelline membrane strength (VMS) were determined at 0, 20, and 30 storage days. CLA had minimal effect on fatty acid profiles, relative to c,t reports. CLA-rich yolk viscosity was greater than controls, and CLA yolks maintained higher viscosities during storage. Yolk weight and index were not affected by t,t CLA-rich soy oil. Yolks with the greatest CLA concentrations had the greatest VMS after 20 days of storage, and yolks containing lower CLA levels maintained greater VMS throughout 30 days of storage, relative to controls.

Sunflower (Helianthus annuus L.) seed dormancy is regulated by reactive oxygen species (ROS) and can be alleviated by incubating dormant embryos in the presence of methylviologen (MV), a ROS-generating compound. Ethylene alleviates sunflower seed dormancy whereas abscisic acid (ABA) represses germination. The purposes of this study were to identify the molecular basis of ROS effect on seed germination and to investigate their possible relationship with hormone signalling pathways. Ethylene treatment provoked ROS generation in embryonic axis whereas ABA had no effect on their production. The beneficial effect of ethylene on germination was lowered in the presence of antioxidant compounds, and MV suppressed the inhibitory effect of ABA. MV treatment did not alter significantly ethylene nor ABA production during seed imbibition. Microarray analysis showed that MV treatment triggered differential expression of 120 probe sets (59 more abundant and 61 less abundant genes), and most of the identified transcripts were related to cell signalling components. Many transcripts less represented in MV-treated seeds were involved in ABA signalling, thus suggesting an interaction between ROS and ABA signalling pathways at the transcriptional level. Altogether, these results shed new light on the crosstalk between ROS and plant hormones in seed germination.

Measurements of photometric variability at different wavelengths provide insights into the vertical cloud structure of brown dwarfs and planetary-mass objects. In seven Hubble Space Telescope consecutive orbits, spanning $\sim$10 h of observing time}, we obtained time-resolved spectroscopy of the planetary-mass T8-dwarf Ross 458C using the near-infrared Wide Field Camera 3. We found spectrophotometric variability with a peak-to-peak signal of 2.62$\pm$0.02 % (in the 1.10-1.60~$\mu$m white light curve). Using three different methods, we estimated a rotational period of 6.75$\pm$1.58~h for the white light curve, and similar periods for narrow $J$- and $H$- band light curves. Sine wave fits to the narrow $J$- and $H$-band light curves suggest a tentative phase shift between the light curves with wavelength when we allow different periods between both light curves. If confirmed, this phase shift may be similar to the phase shift detected earlier for the T6.5 spectral type 2MASS J22282889-310262. We find that, in contrast with 2M2228, the variability of Ross~458C shows evidence for a {color trend} within the narrow $J$-band, but gray variations in the narrow $H$-band. The spectral time-resolved variability of Ross 458C might be potentially due to heterogeneous sulfide clouds in the atmosphere of the object. Our discovery extends the study of spectral modulations of condensate clouds to the coolest T dwarfs, planetary-mass companions., Comment: Accepted in ApJL

An optochemical CO2 sensor is described which uses a phosphorescent reporter dye PtTFPP and a colourimetric pH indicator α-naphtholphthalein incorporated in plastic matrix together with a phase transfer agent tetraoctyl- or cetyltrimethylammonium hydroxide. Good spectral overlap of PtTFPP emission and α-naphtholphthalein absorption at around 650 nm provides efficient energy transfer from PtTFPP via FRET mechanism, thus reducing its phosphorescence lifetime. Experiments were carried out to optimize the composition and working characteristics of such a sensor for the measurement of headspace CO2 in foods packaged under modified atmosphere. The resulting thin film sensor coatings showed robust optical responses to CO2, response (1 min, 99.9%) and recovery times (4 min, 99.9%) from 0 to 100% CO2. As expected, the CO2 sensor showed significant cross-sensitivity to O2 quenching, and this was accounted for by a tandem O2 sensor having similar phosphorescent characteristics but no CO2 sensitivity. Upon storage in an open container, the sensors were stable for at least 14 days at 4 °C and 50 days at −20 °C, however at room temperature they were seen to deteriorate within 7 days loosing colour and sensitivity to CO2. At the same time, in food and modified atmosphere environment the sensor retained its sensitivity to CO2 for 21 days at 4 °C which is sufficient for many packaged products. Migration of sensor components examined with a standard set of standard food stimulants was only detectable in 95% ethanol and in olive oil for PtTFPP (0.06–0.13 μg/ml) and in 50% and 95% ethanol for α-naphtholphthalein (9.86–21.65 μg/ml).

De novo sequencing of complex genomes is one of the main challenges for researchers seeking high-quality reference sequences. Many de novo assemblies are based on short reads, producing fragmented genome sequences. Third-generation sequencing, with read lengths >10 kb, will improve the assembly of complex genomes, but these techniques require high-molecular-weight genomic DNA (gDNA), and gDNA extraction protocols used for obtaining smaller fragments for short-read sequencing are not suitable for this purpose. Methods of preparing gDNA for bacterial artificial chromosome (BAC) libraries could be adapted, but these approaches are time-consuming, and commercial kits for these methods are expensive. Here, we present a protocol for rapid, inexpensive extraction of high-molecular-weight gDNA from bacteria, plants, and animals. Our technique was validated using sunflower leaf samples, producing a mean read length of 12.6 kb and a maximum read length of 80 kb.

A new sensor is described based on a phosphorescent metalloporphyrin dye incorporated in a polymeric membrane, which allows measurement of the two important analytes, oxygen and pH. In such a sensor, the bifunctional dye is quenched by O(2) altering its phosphorescence intensity and lifetime (0-21 kPa O(2)), whereas protonation of the dye causes a major change in the absorption spectrum and also reduces the phosphorescence intensity. As a result, quantification and continuous monitoring of the two analytes can be achieved by (i) simultaneous phosphorescence intensity (O(2), pH) and lifetime (O(2)) measurements and (ii) parallel phosphorescence lifetime (O(2)) and ratiometric absorbance (pH) measurements. Although the first method generally requires sensor calibration in intensity mode, the second provides internal referencing and calibration-free capabilities for both analytes. This approach can be extended to sensing of some other analytes.

International audience; The Frizzled receptor and Dishevelled effector regulate mitotic spindle orientation in both vertebrates and invertebrates, but how Dishevelled orients the mitotic spindle is unknown. Using the Drosophila S2 cell "induced polarity" system, we find that Dishevelled cortical polarity is sufficient to orient the spindle and that Dishevelled's DEP domain mediates this function. This domain binds a C-terminal domain of Mud (the Drosophila NuMA ortholog), and Mud is required for Dishevelled-mediated spindle orientation. In Drosophila, Frizzled-Dishevelled planar cell polarity (PCP) orients the sensory organ precursor (pI) spindle along the anterior-posterior axis. We show that Dishevelled and Mud colocalize at the posterior cortex of pI, Mud localization at the posterior cortex requires Dsh, and Mud loss-of-function randomizes spindle orientation. During zebrafish gastrulation, the Wnt11-Frizzled-Dishevelled PCP pathway orients spindles along the animal-vegetal axis, and reducing NuMA levels disrupts spindle orientation. Overall, we describe a Frizzled-Dishevelled-NuMA pathway that orients division from Drosophila to vertebrates.

A new class of exoplanets is beginning to emerge: planets whose dayside atmospheres more closely resemble stellar atmospheres as most of their molecular constituents dissociate. The effects of the dissociation of these species will be varied and must be carefully accounted for. Here we take the first steps towards understanding the consequences of dissociation and recombination of molecular hydrogen (H$_2$) on atmospheric heat recirculation. Using a simple energy balance model with eastward winds, we demonstrate that H$_2$ dissociation/recombination can significantly increase the day$-$night heat transport on ultra-hot Jupiters (UHJs): gas giant exoplanets where significant H$_2$ dissociation occurs. The atomic hydrogen from the highly irradiated daysides of UHJs will transport some of the energy deposited on the dayside towards the nightside of the planet where the H atoms recombine into H$_2$; this mechanism bears similarities to latent heat. Given a fixed wind speed, this will act to increase the heat recirculation efficiency; alternatively, a measured heat recirculation efficiency will require slower wind speeds after accounting for H$_2$ dissociation/recombination., Comment: 8 pages, 5 figures, accepted for publication in ApJL

The TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS) will consist of twelve units of four high-purity germanium (HPGe) crystals in a common cryostat. The outer contacts of each crystal will be divided into four quadrants and two lateral segments for a total of eight outer contacts. The performance of a prototype HPGe four-crystal unit has been investigated. Integrated noise spectra for all contacts were measured. Energy resolutions, relative efficiencies for both individual crystals and for the entire unit, and peak-to-total ratios were measured with point-like sources. Position-dependent performance was measured by moving a collimated source across the face of the detector.

A possible contribution of alterations in metabolic sequences involved in citrate catabolism, to intracellular accumulation and subsequent release of citrate was investigated in cluster roots of phosphorus (P)-deficient white lupin (Lupinus albus L.). Citrate accumulation during maturation of root clusters was associated with decreased levels of intracellular soluble Pi and ATP, and with reduced rates of respiration. Inhibitor studies with KCN and salicylhydroxamic acid (SHAM) suggest a reduced capacity of both the cytochrome pathway and of the alternative respiration with a concomitant decrease of immunochemically detectable protein levels of the alternative oxidase. Reduced respiration seems to be related to a general impairment of the respiratory system, rather than to limitation of respiratory substrates such as Pi and adenylates, as indicated by the absence of stimulatory effects of the uncoupler CCCP. The citrate/malate ratio in juvenile root clusters with high rates of respiration and low inherent levels of citrate accumulation was increased by short-term application (4–8 h) of azide and SHAM as respiration inhibitors. During maturation of root clusters, a shift from intracellular malic acid to citric acid accumulation was associated also with down-regulation of ATP citrate lyase (ACL), which catalyzes cleavage of citrate into acetyl-CoA and oxaloacetate with a putative function as anapleurotic source for the production of acetyl-CoA under P-deficient conditions. Inhibition of nitrate uptake and assimilation is a general response to P limitation in many plant species including white lupin. Reduced consumption of the amino acceptor 2-oxoglutaric acid as a product of citrate turnover may therefore contribute to increased citrate accumulation. Accordingly, artificial inhibition of nitrate reduction by localized application of tungstate significantly increased the citrate/malate ratio in juvenile root clusters. Lowering the cytosolic pH by external application of propionate stimulated citrate and malate exudation in non-cluster lateral roots and in developing root clusters. This effect was reverted by preincubation with phosphonate to buffer the cytosol. The results suggest that acidification of the cytosol may be an important factor, triggering the transient release of citrate and protons from mature root clusters in P-deficient white lupin.

In order to cope with phosphate deficiency, white lupin produces bottle-brushed like roots, so-called cluster or proteoid roots which are specialized in malate and citrate excretion. Young, developing cluster roots mainly excrete malate whereas mature cluster roots mainly release citrate. Mature proteoid roots excrete four to six times more carboxylates compared with juvenile proteoid roots. Using a cDNA-amplified restriction fragment length polymorphism (AFLP) approach we identified a gene coding for a putative ATP-citrate lyase (ACL) up-regulated in young cluster roots. Cloning of the lupin ACL revealed that plant ACL is constituted by two polypeptides (ACLA and ACLB) encoded by two different genes. This contrasts with the animal ACL, constituted of one polypeptide which covers ACLA and ACLB. The ACL function of the two lupin gene products has been demonstrated by heterologous expression in yeast. Both subunits are required for ACL activity. In lupin cluster roots, our results suggest that ACL activity could be responsible for the switch between malate and citrate excretion in the different developmental stages of cluster roots. In primary roots of lupin and maize, ACL activity was positively correlated with malate exudation. These results show that ACL is implicated in root exudation of organic acids and hence plays a novel role in addition to lipid synthesis. Our results suggest that in addition to lipid biosynthesis, in plants, ACL is implicated in malate excretion.

Standard culture of human induced pluripotent stem cells (hiPSCs) requires basic Fibroblast Growth Factor (bFGF) to maintain the pluripotent state, whereas hiPSC more closely resemble epiblast stem cells than true naïve state ES which requires LIF to maintain pluripotency. Here we show that chemokine (C-C motif) ligand 2 (CCL2) enhances the expression of pluripotent marker genes through the phosphorylation of the signal transducer and activator of transcription 3 (STAT3) protein. Moreover, comparison of transcriptomes between hiPSCs cultured with CCL2 versus with bFGF, we found that CCL2 activates hypoxia related genes, suggesting that CCL2 enhanced pluripotency by inducing a hypoxic-like response. Further, we show that hiPSCs cultured with CCL2 can differentiate at a higher efficiency than culturing with just bFGF and we show CCL2 can be used in feeder-free conditions in the absence of LIF. Taken together, our finding indicates the novel functions of CCL2 in enhancing its pluripotency in hiPSCs.

Cluster root formation in white lupin (Lupinus albus L.) is induced mainly by phosphorus (P) starvation, and seems to be regulated by the endogenous P status of the plant. Increased formation of cluster roots, when indole acetic acid is supplied to the growth medium of P sufficient plants, and inhibitory effects of kinetin application suggest the involvement of endogenous phytohormones (auxins and cytokinins), which may act in an antagonistic manner in the P-starvation response. Phosphorus deficiency-induced adaptations of white lupin, involved in P acquisition and mobilization of sparingly available P sources, are predominantly confined to the cluster roots, and moreover to distinct stages during their development. Increased accumulation and exudation of citrate and a concomitant release of protons were found to be mainly restricted to mature root clusters after prolonged culture (3-4 weeks) under P-deficient conditions. Inhibition of citrate exudation by exogenous application of anion channel antagonists such as ethacrynic- and anthracene-9-carboxylic acids may indicate involvement of an anion channel. Phosphorus deficiency-induced accumulation and subsequent exudation of citric acid seems to be a consequence of both enhanced biosynthesis and reduced turnover of citric acid in the cluster root tissue, indicated by enhanced expression of sucrose synthase, fructokinase, phosphoglucomutase, phosphoenol-pyruvate carboxylase, but reduced activity of aconitase and slower root respiration. The release of acid phosphatase and of phenolic compounds (isoflavonoids) as well as the induction of a putative high-affinity P uptake system was more highly expressed in juvenile, mature and even senescent cluster regions than in apical zones of non-proteoid roots. An AFLP-cDNA library for cluster root-specific gene expression was constructed to assist in the identification of further genes involved in cluster root development. Copyright 2000 Annals of Botany Company

We investigated the carbon, nitrogen, and phosphorus levels in whole fish and gut samples of several species of cyprinids, relating our findings to nutrient flux models. Some differences in whole-fish nutrient content across species, lakes, and seasons, as well as differences across fish length and mass, were found. N and P contents were highest in fathead minnows and lowest in pearl dace, with northern redbelly dace and finescale dace intermediate. Larger fish had higher percent C and lower percent N and P. However, all differences in whole fish C, N, and P chemistry were small. Cyprinids had the following mean composition: carbon, 46%; nitrogen, 9.7%; and phosphorus, 1.5%. The cyprinid molar C:N:P ratio was 242:16:1. These values make cyprinids relatively low in phosphorus compared to other fish that have been previously studied, especially members of the Percidae and Centrarchidae. Gut contents were lower in N and P than the whole fish, and C:N and C:P ratios were correspondingly higher in gut contents...

We have identified two familial defective apo B-100 (FDB) homozygotes by DNA sequencing and have measured affinity of low-density lipoproteins (LDL) and very-low-density lipoprotein (VLDL) remnants for the LDL receptor in vitro. The patients were a 66-year-old man with coronary heart disease (plasma cholesterol level, 9.5 mmol/l before treatment) and his 69-year-old sister, without signs of cardiovascular disease (plasma cholesterol, 12.0 mmol/l before treatment). In both patients, treatment with statins caused a marked fall in plasma cholesterol level. Binding affinity of LDL from the two patients was 10%-20% of normal at 4 degrees C and 37 degrees C. Binding affinity of VLDL remnants was normal. We conclude that (1) residual affinity of LDL in homozygous FDB is high enough to permit significant catabolism via the LDL-receptor pathway, and (2) normal affinity of VLDL remnants permits normal hepatic clearance of precursors of LDL and increased clearance of LDL precursors when receptor activity is stimulated by statins. Residual affinity of LDL and normal affinity of remnants could explain why expression of the FDB mutation is generally milder than that of LDL receptor mutations causing familial hypercholesterolaemia.